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Sample records for ambient pressure estimation

  1. Noninvasive Ambient Pressure Estimation using Ultrasound Contrast Agents -- Invoking Subharmonics for Cardiac and Hepatic Applications

    Science.gov (United States)

    Dave, Jaydev K.

    Ultrasound contrast agents (UCAs) are encapsulated microbubbles that provide a source for acoustic impedance mismatch with the blood, due to difference in compressibility between the gas contained within these microbubbles and the blood. When insonified by an ultrasound beam, these UCAs act as nonlinear scatterers and enhance the echoes of the incident pulse, resulting in scattering of the incident ultrasound beam and emission of fundamental (f0), subharmonic (f0/2), harmonic (n*f0; n ∈ N) and ultraharmonic (((2n-1)/2)*f0; n ∈ N & n > 1) components in the echo response. A promising approach to monitor in vivo pressures revolves around the fact that the ultrasound transmit and receive parameters can be selected to induce an ambient pressure amplitude dependent subharmonic signal. This subharmonic signal may be used to estimate ambient pressure amplitude; such technique of estimating ambient pressure amplitude is referred to as subharmonic aided pressure estimation or SHAPE. This project develops and evaluates the feasibility of SHAPE to noninvasively monitor cardiac and hepatic pressures (using commercially available ultrasound scanners and UCAs) because invasive catheter based pressure measurements are used currently for these applications. Invasive catheter based pressure measurements pose risk of introducing infection while the catheter is guided towards the region of interest in the body through a percutaneous incision, pose risk of death due to structural or mechanical failure of the catheter (which has also triggered product recalls by the USA Food and Drug Administration) and may potentially modulate the pressures that are being measured. Also, catheterization procedures require fluoroscopic guidance to advance the catheter to the site of pressure measurements and such catheterization procedures are not performed in all clinical centers. Thus, a noninvasive technique to obtain ambient pressure values without the catheterization process is clinically

  2. Impact of acoustic pressure on ambient pressure estimation using ultrasound contrast agent

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2010-01-01

    ultrasound. The experimental setup resembles a realistic clinical setup utilizing a single array transducer for transmit and receive. The ambient pressure sensitivity of SonoVue (Bracco, Milano, Italy) was measured twice using two different acoustic driving pressures, which were selected based...... of the subharmonic component to occur at acoustic driving pressures between 300 and 500 kPa. Based on this, the pressure sensitivity was investigated using a driving pressure of 485 and 500 kPa. At 485 kPa, a linear pressure sensitivity of 0.42 dB/kPa was found having a linear correlation coefficient of 0.......94. The second measurement series at 485 kPa showed a sensitivity of 0.41 dB/kPa with a correlation coefficient of 0.89. Based on the measurements at 500 kPa, this acoustic driving pressure was concluded to be too high causing the bubbles to be destroyed. The pressure sensitivity for these two measurement series...

  3. Non-invasive ambient pressure estimation using non-linear ultrasound contrast agents

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup

    Many attempts to find a non-invasive procedure to measure the blood pressure locally in the body have been made. This dissertation focuses on the approaches which utilize highly compressible ultrasound contrast agents as ambient pressure sensors. The literature within the topic has been reviewed...

  4. Ambient Interstellar Pressure and Superbubble Evolution

    CERN Document Server

    Oey, M S

    2004-01-01

    High ambient interstellar pressure is suggested as a possible factor to explain the ubiquitous observed growth-rate discrepancy for supernova-driven superbubbles and stellar wind bubbles. Pressures of P/k ~ 1e5 cm-3 K are plausible for regions with high star formation rates, and these values are intermediate between the estimated Galactic mid-plane pressure and those observed in starburst galaxies. High-pressure components also are commonly seen in Galactic ISM localizations. We demonstrate the sensitivity of shell growth to the ambient pressure, and suggest that superbubbles ultimately might serve as ISM barometers.

  5. Effects of Ambient Pressure on Bubble Characteristics

    Institute of Scientific and Technical Information of China (English)

    卢新培; 刘明海; 江中和; 潘垣

    2002-01-01

    The effects of the ambient pressure Pambient on the bubble characteristics of pulsed discharge in water are investigated. The simulation results show that, when Pambient increases from 1 atm to 100 atm, the bubble radius R decreases from 4cma to 7mm, and its pulsation period decreases frown 8ms to 0.2ms. The results also show that the peak pressure of the first shock wave is independent of Pambient, but the peak pressure of the second shock wave caused by the bubble re-expansion decreases when Pambient increases. On the other hand, the larger the ambient pressure, the larger the peak pressure of the plasma in the bubble, while the plasma temperature is independent of Pambient.

  6. Improved Ambient Pressure Pyroelectric Ion Source

    Science.gov (United States)

    Beegle, Luther W.; Kim, Hugh I.; Kanik, Isik; Ryu, Ernest K.; Beckett, Brett

    2011-01-01

    The detection of volatile vapors of unknown species in a complex field environment is required in many different applications. Mass spectroscopic techniques require subsystems including an ionization unit and sample transport mechanism. All of these subsystems must have low mass, small volume, low power, and be rugged. A volatile molecular detector, an ambient pressure pyroelectric ion source (APPIS) that met these requirements, was recently reported by Caltech researchers to be used in in situ environments.

  7. Ambient-pressure silica aerogel films

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, S.S. [New Mexico Univ., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States); Hurd, A.J. [Sandia National Labs., Albuquerque, NM (United States)

    1994-12-31

    Very highly porous (aerogel) silica films with refractive index in the range 1.006--1.05 (equivalent porosity 98.5--88%) were prepared by an ambient-pressure process. It was shown earlier using in situ ellipsometric imaging that the high porosity of these films was mainly attributable to the dilation or `springback` of the film during the final stage of drying. This finding was irrefutably reconfirmed by visually observing a `springback` of >500% using environmental scanning electron microscopy (ESEM). Ellipsometry and ESEM also established the near cent per cent reversibility of aerogel film deformation during solvent intake and drying. Film thickness profile measurements (near the drying line) for the aerogel, xerogel and pure solvent cases are presented from imaging ellipsometry. The thickness of these films (crack-free) were controlled in the range 0.1-3.5 {mu}m independent of refractive index.

  8. Simulation of microbubble response to ambient pressure changes

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2008-01-01

    The theory on microbubbles clearly indicates a relation between the ambient pressure and the acoustic behavior of the bubble. The purpose of this study was to optimize the sensitivity of ambient pressure measurements, using the subharmonic component, through microbubble response simulations....... The behaviour of two different contrast agents was investigated as a function of driving pulse and ambient overpressure, pov. Simulations of Levovist using a rectangular driving pulse show an almost linear reduction in the subharmonic component as pov is increased. For a 20 cycles driving pulse, a reduction...... is not completely linear as a function of the ambient pressure....

  9. Effect of ambient-pressure reduction on multibubble sonochemiluminescence

    Science.gov (United States)

    Tuziuti, Toru; Hatanaka, Shin-ichi; Yasui, Kyuichi; Kozuka, Teruyuki; Mitome, Hideto

    2002-04-01

    The effect of ambient-pressure reduction on multibubble sonochemiluminescence (MBSCL) is studied experimentally with a luminol solution through measurements of MBSCL intensity as a function of ultrasound irradiation time, applied voltage to a transducer and ultrasonic frequencies to accomplish high efficiency in chemical reactions. From the measurement of ambient-pressure dependence, it is shown that there is an ambient pressure that produces the maximum intensity of the MBSCL and the maximum intensity appears at higher ambient pressure as the applied voltage to the transducer increases. The highest intensity of MBSCL is obtained by appropriate reduction of ambient pressure both for various applied voltages and frequencies. This is caused by both the number of bubbles induced with supersaturation of the gas in a luminol solution and the variation in bubble dynamics.

  10. Ambient pressure sensitivity of microbubbles investigated through a parameter study

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2009-01-01

    Measurements on microbubbles clearly indicate a relation between the ambient pressure and the acoustic behavior of the bubble. The purpose of this study was to optimize the sensitivity of ambient pressure measurements, using the subharmonic component, through microbubble response simulations....... 1999, who found a linear reduction of 9.6 dB. Further simulations of Levovist show that also the shape and the acoustic pressure of the driving pulse are very important factors. The best pressure sensitivity of Levovist was found to be 0.88 dB/kPa. For Sonazoid, a sensitivity of 1.14 dB/kPa has been...

  11. Estimation of vapour pressure and partial pressure of subliming compounds by low-pressure thermogravimetry

    Indian Academy of Sciences (India)

    G V Kunte; Ujwala Ail; P K Ajikumar; A K Tyagi; S A Shivashankar; A M Umarji

    2011-12-01

    A method for the estimation of vapour pressure and partial pressure of subliming compounds under reduced pressure, using rising temperature thermogravimetry, is described in this paper. The method is based on our recently developed procedure to estimate the vapour pressure from ambient pressure thermogravimetric data using Langmuir equation. Using benzoic acid as the calibration standard, vapour pressure–temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4-pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined as a function of temperature. Such data can be useful for the deposition of multi-metal oxide thin films or doped thin films by chemical vapour deposition (CVD).

  12. In vitro measurement of ambient pressure changes using a realistic clinical setup

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2008-01-01

    cosine tapered pulse with a center frequency of 4 MHz and an acoustic pressure of 485 kPa was used for excitation. 64 elements were used in receive and the RF data was filtered and beamformed before further processing. To compensate for variations in bubble response and to make the estimates more robust...... have indicated that the amplitude of the subharmonic response from contrast agents is sensitive to the ambient pressure. This paper presents results from a new experimental setup for measuring the subharmonic response of a contrast agent when subjected to ambient over pressure. The setup is very...... flexible offering completely arbitrary excitation and data acquisition, fast and accurate ambient pressure control, and precise timing. More importantly, it resembles a realistic clinical setup using a single array transducer for transmit and receive. The standard signal processing steps usually seen...

  13. Photoelectron Spectroscopy under Ambient Pressure and Temperature Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ogletree, D. Frank; Bluhm, Hendrik; Hebenstreit, Eleonore B.; Salmeron, Miquel

    2009-02-27

    We describe the development and applications of novel instrumentation for photoemission spectroscopy of solid or liquid surfaces in the presence of gases under ambient conditions or pressure and temperature. The new instrument overcomes the strong scattering of electrons in gases by the use of an aperture close to the surface followed by a differentially-pumped electrostatic lens system. In addition to the scattering problem, experiments in the presence of condensed water or other liquids require the development of special sample holders to provide localized cooling. We discuss the first two generations of Ambient Pressure PhotoEmission Spectroscopy (APPES) instruments developed at synchrotron light sources (ALS in Berkeley and BESSY in Berlin), with special focus on the Berkeley instruments. Applications to environmental science and catalytic chemical research are illustrated in two examples.

  14. Processing of subharmonic signals from ultrasound contrast agents to determine ambient pressures.

    Science.gov (United States)

    Dave, Jaydev K; Halldorsdottir, Valgerdur G; Eisenbrey, John R; Forsberg, Flemming

    2012-04-01

    Subharmonic-aided pressure estimation (SHAPE) is a technique that utilizes the subharmonic emissions, occurring at half the insonation frequency, from ultrasound contrast agents to estimate ambient pressures. The purpose of this work was to compare the performance of different processing techniques for the raw radiofrequency (rf) data acquired for SHAPE. A closed loop flow system was implemented circulating reconstituted Sonazoid (GE Healthcare, Oslo, Norway; 0.2 ml for 750 ml diluent) and the beam-formed unprocessed rf data were obtained from a 4 mm diameter lumen of a Doppler flow phantom (ATS Laboratories, Inc., Bridgeport, CT) using a SonixRP scanner (Ultrasonix, Richmond, BC, Canada). The transmit frequency and incident acoustic pressures were set to 2.5 MHz and 0.22 MPa, respectively, in order to elicit Sonazoid subharmonic emissions that are ambient-pressure sensitive. The time-varying ambient pressures within the flow phantom were recorded by a Millar pressure catheter. Four techniques for extracting the subharmonic amplitude from the rf data were tested along with two noise filtering techniques to process this data. Five filter orders were tested for the noise removing filters. The performance was evaluated based on the least root-mean-square errors reported after linear least-square regression analyses of the subharmonic data and the pressure catheter data and compared using a repeated ANOVA. When the subharmonic amplitudes were extracted as the mean value within a 0.2 MHz bandwidth about 1.25 MHz and when the resulting temporally-varying subharmonic signal was median filtered with an order of 500, the filtered subharmonic signal significantly predicted the ambient pressures (r2 = 0.90; p subharmonic data extracted as the mean value within a 0.2 MHz bandwidth about the theoretical subharmonic frequency turned out to be the best technique to process acoustic data for SHAPE. The implementation of this technique on ultrasound scanners may permit real

  15. [Research on Raman spectra of isooctane at ambient temperature and ambient pressure to 1. 2 GPa].

    Science.gov (United States)

    Zhang, Fei-fei; Zheng, Hai-fei

    2012-03-01

    The experimental study of the Raman spectral character for liquid isooctane (2,2,4-trimethylpentane, ATM) was con ducted by moissanite anvil cell at the pressure of 0-1.2 GPa and the ambient temperature. The results show that the Raman peaks of the C-H stretching vibration shift to higher frenquencies with increasing pressures. The relations between the system pressure and peaks positions is given as following: v2 873 = 0.002 8P+2 873.3; v2 905 = 0.004 8P+2 905.4; v2 935 = 0.002 7P+ 2 935.0; v2 960 = 0.012P+2 960.9. The Raman spectra of isooctane abruptly changed at the pressure about 1.0 GPa and the liquid-solid phase transition was observed by microscope. With the freezing pressure at ambient temperature and the melting temperature available at 1 atm, the authors got the liquid-solid phase diagram of isooctane. According to Clapeyron equation, the authors obtained the differences of volume and entropy for the liquid-solid phase transition of isooctane: deltaV(m) = 4.46 x 10(-6) m3 x mol-1 and deltaS = -30.32 J x K(-1) x mol(-1).

  16. Effect of gas pressure on ionization of ambient gas

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An Nd: YAG pulsed laser (145 mJ) was used to ablate aluminum target and Ar was used as protecting gas. Time-and space-resolved spectra of the plasmas under pressure 100 Pa, 1 kPa, 10 kPa and 100 kPa were acquired with time- and space-resolved technique. The characteristics of the plasma radiating under each pressure were briefly described, and the laws of Ar characteristical radiaton were analyzed in detail. Based on the profile of Ar characteristical radiation under these pressure, the relation between protecting gas pressure and its ionization was briefly discussed, and explained with quantum theory. Farther more, the mechanism of ambient gas ionization was investigated. As the result, it was suggested that the main mechanism inducing protecting gas to ionize should be the absorption of the plasma continuum radiation by the gas.

  17. On Modal Parameter Estimates from Ambient Vibration Tests

    DEFF Research Database (Denmark)

    Agneni, A.; Brincker, Rune; Coppotelli, B.

    2004-01-01

    Modal parameter estimates from ambient vibration testing are turning into the preferred technique when one is interested in systems under actual loadings and operational conditions. Moreover, with this approach, expensive devices to excite the structure are not needed, since it can be adequately...

  18. Effects of ambient pressure on the subharmonic response from encapsulated microbubbles

    CERN Document Server

    Mobadersany, Nima; Sarkar, Kausik

    2015-01-01

    Subharmonic response from contrast microbubbles as a function of ambient overpressure is numerically investigated for subharmonic aided noninvasive estimation of local organ level blood pressure. Three different interfacial rheological models for the encapsulation is used with material parameters appropriate for a common lipid coated contrast agent Sonazoid. The subharmonic response is seen to either decrease, increase or vary nonmonotonically with increasing ambient pressure. Compared to a free microbubbles important differences arise due to the encapsulation. Specifically due to the enhanced damping due to encapsulation, the range of excitation over which subharmonic is seen is broader than that in free microbubbles. This results in different trends of subharmonic response at the same excitation frequency for different excitation pressures. The observed behaviors are explained by investigating subharmonic generation threshold and resonance frequency.

  19. Ambient pressure photoelectron spectroscopy: Practical considerations and experimental frontiers

    Science.gov (United States)

    Trotochaud, Lena; Head, Ashley R.; Karslıoğlu, Osman; Kyhl, Line; Bluhm, Hendrik

    2017-02-01

    Over the past several decades, ambient pressure x-ray photoelectron spectroscopy (APXPS) has emerged as a powerful technique for in situ and operando investigations of chemical reactions under relevant ambient atmospheres far from ultra-high vacuum conditions. This review focuses on exemplary cases of APXPS experiments, giving special consideration to experimental techniques, challenges, and limitations specific to distinct condensed matter interfaces. We discuss APXPS experiments on solid/vapor interfaces, including the special case of 2D films of graphene and hexagonal boron nitride on metal substrates with intercalated gas molecules, liquid/vapor interfaces, and liquid/solid interfaces, which are a relatively new class of interfaces being probed by APXPS. We also provide a critical evaluation of the persistent limitations and challenges of APXPS, as well as the current experimental frontiers.

  20. Preparation and Characterization of Silica Aerogels Derived from Ambient Pressure

    Institute of Scientific and Technical Information of China (English)

    Jun SHEN; Zhihua ZHANG; Guangming WU; Bin ZHOU; Xingyuan NI; Jue WANG

    2006-01-01

    Silica aerogels were prepared by sol-gel technique from industrial silicon derivatives (polyethoxydisiloxanes, E40), followed by silylation and drying under ambient pressure. The specific surface area, pore size distribution and thermal conductivity of the silica aerogels were investigated and the results showed that the diameter of the silica particles is about 6 nm and the average pore size of the silica aerogels is 14.7 nm. The specific temperature and pressure of 1.01×105 Pa. The Si-CH3 groups were also detected on the internal surface of the silica aerogels, which show hydrophobic. Silica aerogels derived by this technique is low cost and have wide applications.

  1. CO oxidation on Pt(111) at near ambient pressures

    Energy Technology Data Exchange (ETDEWEB)

    Krick Calderón, S.; Grabau, M.; Kress, B.; Papp, C. [Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Óvári, L. [MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Rerrich Béla tér 1, 6720 Szeged (Hungary); Steinrück, H.-P. [Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Erlangen Catalysis Resource Center, Egerlandstr. 3, 91058 Erlangen (Germany)

    2016-01-28

    The oxidation of CO on Pt(111) was investigated simultaneously by near ambient pressure X-ray photoelectron spectroscopy and online gas analysis. Different CO:O{sub 2} reaction mixtures at total pressures of up to 1 mbar were used in continuous flow mode to obtain an understanding of the surface chemistry. By temperature-programmed and by isothermal measurements, the onset temperature of the reaction was determined for the different reactant mixtures. Highest turnover frequencies were found for the stoichiometric mixture. At elevated temperatures, the reaction becomes diffusion-limited in both temperature-programmed and isothermal measurements. In the highly active regime, no adsorbates were detected on the surface; it is therefore concluded that the catalyst surface is in a metallic state, within the detection limits of the experiment, under the applied conditions. Minor bulk impurities such as silicon were observed to influence the reaction up to total inhibition by formation of non-platinum oxides.

  2. Bridging the pressure gap: Can we get local quantitative structural information at 'near-ambient' pressures?

    Science.gov (United States)

    Woodruff, D. P.

    2016-10-01

    In recent years there have been an increasing number of investigations aimed at 'bridging the pressure gap' between UHV surface science experiments on well-characterised single crystal surfaces and the much higher (ambient and above) pressures relevant to practical catalyst applications. By applying existing photon-in/photon-out methods and developing instrumentation to allow photoelectron emission to be measured in higher-pressure sample environments, it has proved possible to obtain surface compositions and spectroscopic fingerprinting of chemical and molecular states of adsorbed species at pressures up to a few millibars. None of these methods, however, provide quantitative structural information on the local adsorption sites of isolated atomic and molecular adsorbate species under these higher-pressure reaction conditions. Methods for gaining this information are reviewed and evaluated.

  3. Damping estimation using free decays and ambient vibration tests

    Science.gov (United States)

    Magalhães, Filipe; Cunha, Álvaro; Caetano, Elsa; Brincker, Rune

    2010-07-01

    This paper studies the quality of modal damping ratios estimates based on ambient and free vibration tests using both numerical simulations and data collected on large Civil Engineering structures where both tests were performed. The simulated data allowed to study the influence of factors like non-proportional damping or proximity of natural frequencies on the quality of the estimates and also to illustrate the influence of the identification algorithms parameters on the accuracy of the results. The analysis of data collected on a cable-stayed bridge, on the suspended roof of a stadium and on a footbridge permitted to compare the results of both testing approaches in real applications where some factors that cannot be realistically included in the numerical simulations can play an important role. The processing of ambient vibration responses is performed with two output-only identification approaches: frequency domain decomposition and stochastic subspace identification methods. The numerically simulated and the measured free decays were analyzed with a simple method based on filters and fitting of exponential decays and also with the use of subspace models.

  4. Superconducting Properties of MgB2 Prepared by High and Ambient Pressures

    Institute of Scientific and Technical Information of China (English)

    REN Zhi-An; CHE Guang-Can; ZHAO Zhong-Xian; CHEN Hong; DONG Cheng; NI Yong-Ming; JIA Shun-Lian; WEN Hai-Hu

    2001-01-01

    The new superconductor MgB2 has been prepared in two ways, by high pressure and ambient pressure synthesis.The superconducting properties were measured and compared. It is found that the sample prepared by highpressure is much denser than that prepared under ambient pressure. Accordingly the high pressure sample has avery narrow transition width and a much higher bulk critical current densityC

  5. Ambient Pressure Synthesis of Nanostructured Tungsten Oxide Crystalline Films

    Directory of Open Access Journals (Sweden)

    H. X. Zhang

    2008-01-01

    Full Text Available We report the results of the ambient pressure synthesis of tungsten oxide nanowires and nanoparticles on AlN substrates using the hot filament CVD techniques. The morphologic surface, crystallographic structures, chemical compositions, and bond structures of the obtained samples have been investigated using scanning electron microscopy (SEM, X-ray diffraction (XRD, energy dispersive X-ray spectroscopy (EDX, and Raman scattering, respectively. Different morphologies were observed for different substrate temperatures, but otherwise identical growth conditions. The experimental measurements reveal the evolutions of the crystalline states and bond structures following the substrate temperatures. Besides, different substrate materials also affected the tungsten oxide nanostructures. Bundles of wire-type tungsten oxide nanowires with a length of up to 5 mm were obtained on Al2O3 substrate. Furthermore, the sensitive properties of the super long nanowires to the gas and different temperature were investigated. The dependence of the sensitivity of tungsten oxide nanowires to the methane as a function of the time was obtained. The sensitive properties of the tungsten oxide nanowires have almost linear relationship with the temperature.

  6. Bicellar mixture phase behavior examined by variable-pressure deuterium NMR and ambient pressure DSC.

    Science.gov (United States)

    Uddin, Md Nasir; Morrow, Michael R

    2010-07-20

    Variable-pressure deuterium nuclear magnetic resonance ((2)H NMR) has been used to study the pressure-temperature phase diagram of bicellar mixtures containing 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC). Spectra were obtained for DMPC-d(54)/DHPC (3:1), DMPC-d(54)/DHPC (4.4:1), DMPC/DHPC-d(22) (3:1), and DMPC/DHPC-d(22) (4.4:1) in the range 10-68 degrees C at ambient pressure, 66 MPa, 102 MPa, and 135 MPa. Isotropic-to-nematic and nematic-to-lamellar transition temperatures were found to rise with pressure at approximately 0.15 and approximately 0.14 degrees C/MPa, respectively, for DMPC-d(54)/DHPC (3:1) and at at approximately 0.19 and approximately 0.18 degrees C/MPa, respectively, for DMPC-d(54)/DHPC (4.4:1). Pressure had little effect on the range of DMPC-d(54) chain orientational order through the nematic phase temperature range, but the behavior of chain orientational order at the nematic-to-lamellar transition was found to vary slightly with pressure. Comparison of differential scanning calorimetry (DSC) observations with ambient-pressure (2)H NMR observations of DMPC-d(54) in the bicellar mixtures suggests that absorption of heat persists for a few degrees above the onset of axially symmetric DMPC-d(54) reorientation.

  7. The relation between composition in laser absorption region and ambient pressure

    Institute of Scientific and Technical Information of China (English)

    Yang Bo; Zhu Jin-Rong; Yang Yan-Nan; Shen Zhong-Hua; Lu Jian; Ni Xiao-Wu

    2008-01-01

    In this paper,the compositions in a laser absorption region can be determined from the experiment of laser impulse coupling.When the ambient pressure varies from 9325 to 33325Pa,the compositions are vapour and plasma;while from 35325 to 101325Pa,they are ambient air and plasma.By analysing the relation between the degree of compression and the ambient pressure,the compositions can be determined and the variation of plasma can be explained.

  8. Design principles for high-pressure force fields: Aqueous TMAO solutions from ambient to kilobar pressures

    Science.gov (United States)

    Hölzl, Christoph; Kibies, Patrick; Imoto, Sho; Frach, Roland; Suladze, Saba; Winter, Roland; Marx, Dominik; Horinek, Dominik; Kast, Stefan M.

    2016-04-01

    Accurate force fields are one of the major pillars on which successful molecular dynamics simulations of complex biomolecular processes rest. They have been optimized for ambient conditions, whereas high-pressure simulations become increasingly important in pressure perturbation studies, using pressure as an independent thermodynamic variable. Here, we explore the design of non-polarizable force fields tailored to work well in the realm of kilobar pressures - while avoiding complete reparameterization. Our key is to first compute the pressure-induced electronic and structural response of a solute by combining an integral equation approach to include pressure effects on solvent structure with a quantum-chemical treatment of the solute within the embedded cluster reference interaction site model (EC-RISM) framework. Next, the solute's response to compression is taken into account by introducing pressure-dependence into selected parameters of a well-established force field. In our proof-of-principle study, the full machinery is applied to N,N,N-trimethylamine-N-oxide (TMAO) in water being a potent osmolyte that counteracts pressure denaturation. EC-RISM theory is shown to describe well the charge redistribution upon compression of TMAO(aq) to 10 kbar, which is then embodied in force field molecular dynamics by pressure-dependent partial charges. The performance of the high pressure force field is assessed by comparing to experimental and ab initio molecular dynamics data. Beyond its broad usefulness for designing non-polarizable force fields for extreme thermodynamic conditions, a good description of the pressure-response of solutions is highly recommended when constructing and validating polarizable force fields.

  9. Robust seismic velocity change estimation using ambient noise recordings

    Science.gov (United States)

    Daskalakis, E.; Evangelidis, C. P.; Garnier, J.; Melis, N. S.; Papanicolaou, G.; Tsogka, C.

    2016-06-01

    We consider the problem of seismic velocity change estimation using ambient noise recordings. Motivated by Zhan et al., we study how the velocity change estimation is affected by seasonal fluctuations in the noise sources. More precisely, we consider a numerical model and introduce spatio-temporal seasonal fluctuations in the noise sources. We show that indeed, as pointed out by Zhan et al., the stretching method is affected by these fluctuations and produces misleading apparent velocity variations which reduce dramatically the signal to noise ratio of the method. We also show that these apparent velocity variations can be eliminated by an adequate normalization of the cross-correlation functions. Theoretically we expect our approach to work as long as the seasonal fluctuations in the noise sources are uniform, an assumption which holds for closely located seismic stations. We illustrate with numerical simulations in homogeneous and scattering media that the proposed normalization significantly improves the accuracy of the velocity change estimation. Similar behaviour is also observed with real data recorded in the Aegean volcanic arc. We study in particular the volcano of Santorini during the seismic unrest of 2011-2012 and observe a decrease in the velocity of seismic waves which is correlated with GPS measured elevation.

  10. Estimated vapor pressure for WTP process streams

    Energy Technology Data Exchange (ETDEWEB)

    Pike, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Poirier, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-01-01

    Design assumptions during the vacuum refill phase of the Pulsed Jet Mixers (PJMs) in the Hanford Waste Treatment and Immobilization Plant (WTP) equate the vapor pressure of all process streams to that of water when calculating the temperature at which the vacuum refill is reduced or eliminated. WTP design authority asked the authors to assess this assumption by performing calculations on proposed feed slurries to calculate the vapor pressure as a function of temperature. The vapor pressure was estimated for each WTP waste group. The vapor pressure suppression caused by dissolved solids is much greater than the increase caused by organic components such that the vapor pressure for all of the waste group compositions is less than that of pure water. The vapor pressure for each group at 145°F ranges from 81% to 98% of the vapor pressure of water. If desired, the PJM could be operated at higher temperatures for waste groups with high dissolved solids that suppress vapor pressure. The SO4 group with the highest vapor pressure suppression could be operated up to 153°F before reaching the same vapor pressure of water at 145°F. However, most groups would reach equivalent vapor pressure at 147 to 148°F. If any of these waste streams are diluted, the vapor pressure can exceed the vapor pressure of water at mass dilution ratios greater than 10, but the overall effect is less than 0.5%.

  11. Modeling subharmonic response from contrast microbubbles as a function of ambient static pressure.

    Science.gov (United States)

    Katiyar, Amit; Sarkar, Kausik; Forsberg, Flemming

    2011-04-01

    Variation of subharmonic response from contrast microbubbles with ambient pressure is numerically investigated for non-invasive monitoring of organ-level blood pressure. Previously, several contrast microbubbles both in vitro and in vivo registered approximately linear (5-15 dB) subharmonic response reduction with 188 mm Hg change in ambient pressure. In contrast, simulated subharmonic response from a single microbubble is seen here to either increase or decrease with ambient pressure. This is shown using the code BUBBLESIM for encapsulated microbubbles, and then the underlying dynamics is investigated using a free bubble model. The ratio of the excitation frequency to the natural frequency of the bubble is the determining parameter--increasing ambient pressure increases natural frequency thereby changing this ratio. For frequency ratio below a lower critical value, increasing ambient pressure monotonically decreases subharmonic response. Above an upper critical value of the same ratio, increasing ambient pressure increases subharmonic response; in between, the subharmonic variation is non-monotonic. The precise values of frequency ratio for these three different trends depend on bubble radius and excitation amplitude. The modeled increase or decrease of subharmonic with ambient pressure, when one happens, is approximately linear only for certain range of excitation levels. Possible reasons for discrepancies between model and previous experiments are discussed.

  12. Noninvasive estimation of dynamic pressures in vitro and in vivo using the subharmonic response from microbubbles.

    Science.gov (United States)

    Dave, Jaydev K; Halldorsdottir, Valgerdur G; Eisenbrey, John R; Liu, Ji-Bin; McDonald, Maureen E; Dickie, Kris; Leung, Corina; Forsberg, Flemming

    2011-10-01

    The purpose of this study was to develop and validate a noninvasive pressure estimation technique based on subharmonic emissions from a commercially available ultrasound contrast agent and scanner, unlike other studies that have either adopted a single-element transducer approach and/ or use of in-house contrast agents. Ambient pressures were varied in a closed-loop flow system between 0 and 120 mmHg and were recorded by a solid-state pressure catheter as the reference standard. Simultaneously, the ultrasound scanner was operated in pulse inversion mode transmitting at 2.5 MHz, and the unprocessed RF data were captured at different incident acoustic pressures (from 76 to 897 kPa). The subharmonic data for each pulse were extracted using band-pass filtering with averaging, and subsequently processed to eliminate noise. The incident acoustic pressure most sensitive to ambient pressure fluctuations was determined, and then the ambient pressure was tracked over 20 s. In vivo validation of this technique was performed in the left ventricle (LV) of 2 canines. In vitro, the subharmonic signal could track ambient pressure values with r(2) = 0.922 (p subharmonic signal tracked the LV pressures with r(2) > 0.790 (p subharmonic ultrasound-based pressure estimation technique, which can accurately track left ventricular pressures, has been established.

  13. Insights into electrochemical reactions from ambient pressure photoelectron spectroscopy.

    Science.gov (United States)

    Stoerzinger, Kelsey A; Hong, Wesley T; Crumlin, Ethan J; Bluhm, Hendrik; Shao-Horn, Yang

    2015-11-17

    The understanding of fundamental processes in the bulk and at the interfaces of electrochemical devices is a prerequisite for the development of new technologies with higher efficiency and improved performance. One energy storage scheme of great interest is splitting water to form hydrogen and oxygen gas and converting back to electrical energy by their subsequent recombination with only water as a byproduct. However, kinetic limitations to the rate of oxygen-based electrochemical reactions hamper the efficiency in technologies such as solar fuels, fuel cells, and electrolyzers. For these reactions, the use of metal oxides as electrocatalysts is prevalent due to their stability, low cost, and ability to store oxygen within the lattice. However, due to the inherently convoluted nature of electrochemical and chemical processes in electrochemical systems, it is difficult to isolate and study individual electrochemical processes in a complex system. Therefore, in situ characterization tools are required for observing related physical and chemical processes directly at the places where and while they occur and can help elucidate the mechanisms of charge separation and charge transfer at electrochemical interfaces. X-ray photoelectron spectroscopy (XPS), also known as ESCA (electron spectroscopy for chemical analysis), has been used as a quantitative spectroscopic technique that measures the elemental composition, as well as chemical and electronic state of a material. Building from extensive ex situ characterization of electrochemical systems, initial in situ studies were conducted at or near ultrahigh vacuum (UHV) conditions (≤10(-6) Torr) to probe solid-state electrochemical systems. However, through the integration of differential-pumping stages, XPS can now operate at pressures in the torr range, comprising a technique called ambient pressure XPS (AP-XPS). In this Account, we briefly review the working principles and current status of AP-XPS. We use several recent

  14. Quantitative estimates of the volatility of ambient organic aerosol

    Directory of Open Access Journals (Sweden)

    C. D. Cappa

    2010-01-01

    Full Text Available Measurements of the sensitivity of organic aerosol (OA, and its components mass to changes in temperature were recently reported by Huffman et al. (2009 using a tandem thermodenuder-aerosol mass spectrometer (TD-AMS system in Mexico City and the Los Angeles area. Here, we use these measurements to derive quantitative estimates of aerosol volatility within the framework of absorptive partitioning theory using a kinetic model of aerosol evaporation in the TD. OA volatility distributions (or "basis-sets" are determined using several assumptions as to the enthalpy of vaporization (ΔHvap. We present two definitions of "non-volatile OA," one being a global and one a local definition. Based on these definitions, our analysis indicates that a substantial fraction of the organic aerosol is comprised of non-volatile components that will not evaporate under any atmospheric conditions, on the order of 50–80% when the most realistic ΔHvap assumptions are considered. The sensitivity of the total OA mass to dilution and ambient changes in temperature has been assessed for the various ΔHvap assumptions. The temperature sensitivity is relatively independent of the particular ΔHvap assumptions whereas dilution sensitivity is found to be greatest for the low (ΔHvap = 50 kJ/mol and lowest for the high (ΔHvap = 150 kJ/mol assumptions. This difference arises from the high ΔHvap assumptions yielding volatility distributions with a greater fraction of non-volatile material than the low ΔHvap assumptions. If the observations are fit using a 1 or 2-component model the sensitivity of the OA to dilution is unrealistically high. An empirical method introduced by Faulhaber et al. (2009 has also been used to independently estimate a volatility distribution for the ambient OA and is found to give results consistent with the high and variable ΔHvap assumptions. Our

  15. 40 CFR 53.56 - Test for effect of variations in ambient pressure.

    Science.gov (United States)

    2010-07-01

    ... creating an additional pressure drop of 55 mm Hg in the sampler to simulate a heavily loaded filter, such... through the sample filter, measured in actual volume units at the temperature and pressure of the air as... pressure drop shall be installed for the duration of these tests. The sampler's ambient...

  16. Ion-ion reactions for charge reduction of biopolymer at atmospheric pressure ambient

    Institute of Scientific and Technical Information of China (English)

    Yue Ming Zhou; Jian Hua Ding; Xie Zhang; Huan Wen Chen

    2007-01-01

    Extractive electrospray ionization source (EESI) was adapted for ion-ion reaction, which was demonstrated by using a linear quadrupole ion trap mass spectrometer for the first ion-ion reaction of biopolymers in the atmospheric pressure ambient.

  17. Estimating contributions to ambient concentrations in Fort McKay

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-05-15

    The Trace Metal and Air Contaminants (TMAC) Working Group of the Cumulative Effects Environmental Management Association (CEMA) conducts ongoing assessments of the effects of air emissions on people living in the oil sands region of Alberta. An air emissions inventory was recently conducted by the group to identify 41 substances within the region. The inventory was then used to conduct a dispersion modelling assessment that predicted concentrations of substances in the area. Results of the modelling assessment were then used in a health risk assessment for selected community and health receptors. However, a comparison of the dispersion modelling results with available monitoring data showed disagreement, which suggested that predictions of existing and future concentrations may need improvement. This report investigated possible explanations for the differences between dispersion model predictions and monitoring data, with a particular focus on the Fort McKay area. The modelling and monitoring data were compared, and modifications to the dispersion model were recommended. Methods for developing background concentrations for the community of Fort McKay were also discussed. It was noted that emission numbers in the report were consistent with the emission inventory with the exception of nitrogen oxide (NO{sub x}). Concentrations of sulphur dioxide (SO{sub 2}) and nitrogen dioxide (NO{sub 2}) in Fort McKay were also accurate. However, the modelling did not include any community emissions of particulate matter and did a poor job at estimating the ambient concentrations at Fort McKay, as well as hydrogen sulfide (H{sub 2}S) concentrations. It was suggested that changes in weather during the year and the effect of unusual or upset emissions may have contributed to differences. It was concluded that the use of seasonally variable emissions for compounds released from fugitive sources in dispersion modelling reports should be reconsidered. It was also suggested that

  18. Damping Estimation Using Free Decays and Ambient Vibration Tests

    DEFF Research Database (Denmark)

    Magalhães, Filipe; Brincker, Rune; Cunha, Álvaro

    2007-01-01

    The accurate identification of modal damping ratios of Civil Engineering structures is a subject of major importance, as the amplitude of structural vibrations in resonance is inversely proportional to these coefficients. Their experimental identification can be performed either from ambient...... vibration or from free vibration tests. In the last case, the structural response after application of an impulse or after the application of harmonic loads can be used. Ambient vibration tests have the strong advantage of being more practical and economical. However, recent applications of both approaches...

  19. Pressure cycle rheology of nanofluids at ambient temperature

    Science.gov (United States)

    Kanjirakat, Anoop; Sadr, Reza; Yrac, Rommel; Amani, Mahmood

    2015-11-01

    Colloidal suspensions of particles dispersed in a base fluid (or drilling fluid) are commonly used in oil industry to aid the drilling of oil well into the ground. Nanofluids, the colloidal suspensions of nano-sized particles dispersed in a basefluid, have also shown potentials as cooling and abrasive fluids. Utilizing them along with drilling fluids under cyclic high-pressure loadings have not been investigated so far. In the present work, rheological characteristics of silicon oil based nanofluids (prepared with alumina nanoparticles) under pressures up to 1000 bar are investigated using a high-pressure viscometer. The rheological characteristics of nanofluids are measured and are compared with that of the basefluid under increasing and decreasing pressures. Relative viscosity variations of nanofluids were observed to have influenced by the shear rate. In addition, under cyclic high-pressure loading viscosity values of nanofluids are observed to have reduced. This reduction in viscosity at the second pressure cycle could have been caused by the de-agglomeration of particles in the first cycle while working a high-pressure and high-shear condition.

  20. The discharge of fine silica sand in a silo under different ambient air pressures

    Science.gov (United States)

    Hsiau, Shu-San; Liao, Chun-Chung; Lee, Jie-Hsien

    2012-04-01

    Silos are widely used for the industrial scale handling and transportation of powdered and granular materials. The process of discharging powder in a silo involves the flow of both solid particles and an interstitial fluid, usually air. In this study, we experimentally investigate the effects of particle size and ambient pressure on the discharge process in open- and closed-top silos. The discharge rate, pressure drop, and pressure recovery rate are measured and discussed. The results show that the particle size, the diameter of the orifice, and the ambient pressure significantly influence the process of discharge. The effect of air flow is stronger on fine-powdered flow in a closed-top silo. The results indicate that the effects of air flow could be reduced by lowering the ambient pressure. In addition, a normalized critical pressure can be defined beyond which the discharge rate increases dramatically. With reduced ambient pressure, this normalized critical pressure decreases with increasing particle size. Finally, the experimental results are compared with results calculated using the Beverloo equation and Darcy's law.

  1. Comparison between pressurized design and ambient pressure design of hybrid solid oxide fuel cell-gas turbine systems

    Science.gov (United States)

    Park, S. K.; Kim, T. S.

    Design performances of the hybrid solid oxide fuel cell (SOFC)-gas turbine (GT) system have been investigated. A pressurized system and an indirectly heated ambient pressure system were analyzed and their performances were compared. In the baseline layout, the basic performance characteristics of the two system configurations were analyzed, with the cell operation temperature and the pressure ratio as the main design parameters. The pressurized system exhibits a better efficiency owing to not only the higher cell voltage but also more effective utilization of gas turbine, i.e., a larger GT power contribution due to a higher turbine inlet temperature. Independent setting of the turbine inlet temperature was simulated by using the additional fuel supply as well as the air bypass. Increasing the pressure ratio of the gas turbine hardly improves the system efficiency, but the efficiency becomes less sensitive to the turbine inlet temperature. In the ambient pressure system, the available design parameter range is much reduced due to the limit on the recuperator temperature. In particular, design of the ambient pressure hybrid system with a gas turbine of a high pressure ratio does not seem quite feasible because the system efficiency that can be achieved at the possible design conditions is even lower than the efficiency of the SOFC only system.

  2. Coesite Formation at Ambient Pressure and Low Temperatures

    Directory of Open Access Journals (Sweden)

    J. R. Martínez

    2008-01-01

    Full Text Available Partial crystallization of silica xerogel in the form of coesite has been obtained at low-pressure conditions and temperatures of ∼565∘C, in samples containing chlorophyll aggregates dispersed in amorphous silica. Silica xerogel samples were prepared by the sol-gel method using an ethanol:H2O:TEOS molar ratio of 4:11.6:1 and loaded with extracts from frozen spinach leaves. The silica xerogel microstructure of the powders was studied as a function of annealing temperature. It was found that partial crystallization of the glass matrix in the form of coestite was obtained at lower pressure than those specified by the phase diagram. Chlorophyll aggregates were added to the starting solutions which, upon thermal treatments, form small colloidal particles in the glass matrix. The presence of coesite is corroborated by the Rietveld refinement method.

  3. MD studies of electron transfer at ambient and elevated pressures

    Science.gov (United States)

    Giles, Alex; Spooner, Jacob; Weinberg, Noham

    2013-06-01

    The effect of pressure on the rate constants of outer-sphere electron transfer reactions has often been described using the Marcus-Hush theory. This theory agrees well with experiment when internal reorganization of the ionic system is negligible, however it does not offer a recipe for calculation of the effects that result from significant solute restructuring. We have recently developed a molecular dynamics technique that accurately describes structural dependence of molecular volumes in non-polar and weakly polar systems. We are now extending this approach to the case of highly polar ionic systems where both solvent and solute restructuring components are important. For this purpose we construct pressure-dependent two-dimensional surfaces for electron transfer reactions in coordinate system composed of interionic distance and Marcus-type solvent polarization coordinate, and use these surfaces to describe pressure effects on reaction kinetics. R.A. Marcus. J. Chem. Phys. 24, 966 (1956); 24, 979 (1956); 26, 867 (1957). Discuss. Faraday Soc. 29, 21 (1960). Faraday Discuss. Chem. Soc. 74, 7 (1982); N.S. Hush. Trans. Faraday Soc. 57, 557 (1961).

  4. Effect of ambient oxygen pressure on structural, optical and electrical properties of SnO2 thin films

    Institute of Scientific and Technical Information of China (English)

    ZHAO Songqing; ZHOU Yueliang; WANG Shufang; ZHAO Kun; HAN Peng

    2006-01-01

    Polycrystalline SnO2 thin films were deposited on sapphire substrates at 450℃ under different ambient oxygen pressures by pulsed laser deposition technique. The effect of ambient oxygen pressure on the structural, optical and electrical properties of SnO2 thin films was studied. X-ray diffraction and Hall measurements show that increasing the ambient oxygen pressure can improve crystallization of the films and decrease resistivity of the films. A violet emission peak centered at 409 nm was observed from photoluminescence measurements for SnO2 films under deposition ambient oxygen pressure above 5 Pa, which is related to the improvement of crystalline of the films.

  5. ambiental

    Directory of Open Access Journals (Sweden)

    Roque Leal Salcedo

    2008-01-01

    Full Text Available El derecho internacional ambiental es un conocimiento de carácter transversal, que entre otras consideraciones refleja las preocupaciones de la sociedad por la implementación de un modelo de desarrollo sustentable para el respeto a las reglas del medio natural que garantizan la integridad y renovación de los sistemas naturales. El presente artículo enfoca esta visión a través del análisis de material documental revisado, entre ellos tratados internacionales que permiten distinguir el desarrollo del derecho internacional ambiental y el papel de Organización de las Naciones Unidas (ONU, en el propósito común del derecho individual y colectivo de disfrutar de una vida, un ambiente seguro, sano y ecológicamente equilibrado. En función a estas disertaciones las consideraciones finales exponen parte de la visión que ha estructurado la ONU y que representan un aporte considerable en el fomento de la conciencia mundial sobre la necesidad de establecer vínculos entre las naciones para el continuo desarrollo de esta rama del derecho.

  6. Electrocardiogram-assisted blood pressure estimation.

    Science.gov (United States)

    Ahmad, Saif; Chen, Silu; Soueidan, Karen; Batkin, Izmail; Bolic, Miodrag; Dajani, Hilmi; Groza, Voicu

    2012-03-01

    Accurate automatic noninvasive assessment of blood pressure (BP) presents a challenge due to conditions like arrhythmias, obesity, and postural changes that tend to obfuscate arterial amplitude pulsations sensed by the cuff. Researchers tried to overcome this challenge by analyzing oscillometric pulses with the aid of a higher fidelity signal-the electrocardiogram (ECG). Moreover, pulse transit time (PTT) was employed to provide an additional method for BP estimation. However, these methods were not fully developed, suitably integrated, or tested. To address these issues, we present a novel method whereby ECG-assisted oscillometric and PTT (measured between ECG R-peaks and maximum slope of arterial pulse peaks) analyses are seamlessly integrated into the oscillometric BP measurement paradigm. The method bolsters oscillometric analysis (amplitude modulation) with more reliable ECG R-peaks provides a complementary measure with PTT analysis (temporal modulation) and fuses this information for robust BP estimation. We have integrated this technology into a prototype that comprises a BP cuff with an embedded conductive fabric ECG electrode, associated hardware, and algorithms. A pilot study has been undertaken on ten healthy subjects (150 recordings) to validate the performance of our prototype against United States Food and Drug Administration approved Omron oscillometric monitor (HEM-790IT). Our prototype achieves mean absolute difference of less than 5 mmHg and grade A as per the British Hypertension Society protocol for estimating BP, with the reference Omron monitor.

  7. A lab-based ambient pressure x-ray photoelectron spectrometer with exchangeable analysis chambers

    Energy Technology Data Exchange (ETDEWEB)

    Newberg, John T., E-mail: jnewberg@udel.edu; Arble, Chris; Goodwin, Chris; Khalifa, Yehia; Broderick, Alicia [Department of Chemistry & Biochemistry, University of Delaware, Newark, Delaware 19716 (United States); Åhlund, John [Scienta AB, Box 15120, 750 15 Uppsala (Sweden)

    2015-08-15

    Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful spectroscopy tool that is inherently surface sensitive, elemental, and chemical specific, with the ability to probe sample surfaces under Torr level pressures. Herein, we describe the design of a new lab-based APXPS system with the ability to swap small volume analysis chambers. Ag 3d(5/2) analyses of a silver foil were carried out at room temperature to determine the optimal sample-to-aperture distance, x-ray photoelectron spectroscopy analysis spot size, relative peak intensities, and peak full width at half maximum of three different electrostatic lens modes: acceleration, transmission, and angular. Ag 3d(5/2) peak areas, differential pumping pressures, and pump performance were assessed under varying N{sub 2}(g) analysis chamber pressures up to 20 Torr. The commissioning of this instrument allows for the investigation of molecular level interfacial processes under ambient vapor conditions in energy and environmental research.

  8. Diffusion in the gas phase: the effects of ambient pressure and gas composition.

    Science.gov (United States)

    Paganelli, C V; Rahn, A A; Wangensteen, O D

    1975-12-01

    Gas transport across the pores of a hen's egg shell occurs by a process of diffusion in the gas phase and for any particular gas depends upon its diffusion coefficient and the pore geometry. The egg shell is thus a convenient model for measuring the diffusive permeability of the shell to a given gas species when its diffusion coefficient is altered by either a change in ambient pressure or by changing the second gas in the diffusion pathway. In this study the permeability of the shell to water vapor and O2 was inversely proportional to ambient pressures over the range of .06 to 8 atmospheres' absolute (ata). The permeability of the shell to water vapor in a He environment (KH20, He) was 2.4 times KH20, air. If KO2, N2 is taken as unity, the permeabilities of the shell to O2 in He, Ar, CO2 and SF6 are 3.38, 0.95, 0.88, and 0.52, respectively. The results are interpreted in terms of the Chapman-Enskog equation, from which binary diffusion coefficients can be predicted for given gas pairs and ambient pressures. These results also provide explantations for the structural modification of egg shells in altitude-adapted chickens, and for the reduced insensible water loss in man at high ambient pressure.

  9. Seismic waves estimation and wavefield decomposition: application to ambient vibrations

    Science.gov (United States)

    Maranò, Stefano; Reller, Christoph; Loeliger, Hans-Andrea; Fäh, Donat

    2012-10-01

    Passive seismic surveying methods represent a valuable tool in local seismic hazard assessment, oil and gas prospection, and in geotechnical investigations. Array processing techniques are used in order to estimate wavefield properties such as dispersion curves of surface waves and ellipticity of Rayleigh waves. However, techniques presently in use often fail to properly merge information from three-components sensors and do not account for the presence of multiple waves. In this paper, a technique for maximum likelihood estimation of wavefield parameters including direction of propagation, velocity of Love waves and Rayleigh waves, and ellipticity of Rayleigh waves is described. This technique models jointly all the measurements and all the wavefield parameters. Furthermore it is possible to model the simultaneous presence of multiple waves. The performance of this technique is evaluated on a high-fidelity synthetic data set and on real data. It is shown that the joint modelling of all the sensor components, decreases the variance of wavenumber estimates and allows the retrieval of the ellipticity value together with an estimate of the prograde/retrograde motion.

  10. Air Entrainment in Dynamic Wetting: Knudsen Effects and the Influence of Ambient Air Pressure

    CERN Document Server

    Sprittles, James E

    2015-01-01

    Recent experiments on coating flows and liquid drop impact both demonstrate that wetting failures caused by air entrainment can be suppressed by reducing the ambient gas pressure. Here, it is shown that non-equilibrium effects in the gas can account for this behaviour, with ambient pressure reductions increasing the gas' mean free path and hence the Knudsen number $Kn$. These effects first manifest themselves through Maxwell slip at the gas' boundaries so that for sufficiently small $Kn$ they can be incorporated into a continuum model for dynamic wetting flows. The resulting mathematical model contains flow structures on the nano-, micro- and milli-metre scales and is implemented into a computational platform developed specifically for such multiscale phenomena. The coating flow geometry is used to show that for a fixed gas-liquid-solid system (a) the increased Maxwell slip at reduced pressures can substantially delay air entrainment, i.e. increase the `maximum speed of wetting', (b) unbounded maximum speeds ...

  11. Quantitative measurement of radiation pressure on a microcantilever in ambient environment

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Dakang; Munday, Jeremy N., E-mail: jnmunday@umd.edu [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Garrett, Joseph L. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

    2015-03-02

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Micro/nano-mechanical transducers have become sensitive enough that radiation pressure can influence these systems. However, photothermal effects often accompany and overwhelm the radiation pressure, complicating its measurement. In this letter, we investigate the radiation force on an uncoated silicon nitride microcantilever in ambient conditions. We identify and separate the radiation pressure and photothermal forces through an analysis of the cantilever's frequency response. Further, by working in a regime where radiation pressure is dominant, we are able to accurately measure the radiation pressure. Experimental results are compared to theory and found to agree within the measured and calculated uncertainties.

  12. Method development estimating ambient mercury concentration from monitored mercury wet deposition

    Directory of Open Access Journals (Sweden)

    S. M. Chen

    2013-05-01

    Full Text Available Speciated atmospheric mercury data have recently been monitored at multiple locations in North America; but the spatial coverage is far less than the long-established mercury wet deposition network. The present study describes a first attempt linking ambient concentration with wet deposition using Beta distribution fitting of a ratio estimate. The mean, median, mode, standard deviation, and skewness of the fitted Beta distribution parameters were generated using data collected in 2009 at 11 monitoring stations. Comparing the normalized histogram and the fitted density function, the empirical and fitted Beta distribution of the ratio shows a close fit. The estimated ambient mercury concentration was further partitioned into reactive gaseous mercury and particulate bound mercury using linear regression model developed by Amos et al. (2012. The method presented here can be used to roughly estimate mercury ambient concentration at locations and/or times where such measurement is not available but where wet deposition is monitored.

  13. Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

    Institute of Scientific and Technical Information of China (English)

    杜文峰; 胡文瑞

    2003-01-01

    For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal radiation (e.g. for atmosphere of O2-N2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere. As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit and absorb the thermal radiation (e.g. for atmosphere of O2-CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.

  14. Spatial coherences of the sound pressure and the particle velocity in underwater ambient noise

    Institute of Scientific and Technical Information of China (English)

    YAN Jin; LUO Xianzhi; HOU Chaohuan

    2007-01-01

    The spatial coherences were investigated between the sound pressure and the three orthogonal components of the particle velocity in underwater ambient noise. Based on the ray theory, integral expression was derived for the spatial coherence matrix of the sound pressure and the particle velocity in a stratified ocean with dipole noise sources homogenously distributed on the surface. The integrand includes a multiplying factor of the vertical directivity of the noise intensity, and the layered ocean environment affects the spatial coherences via this directivity factor. For a shallow water environment and a semi-infinite homogenous medium, the coherence calculation results were given. It was showed that the sound speed profile and the sea bottom could not be neglected in determining the spatial coherences of the ambient noise vector field.

  15. Response of Microscopic Bubbles to Sudden Decrease of Ambient Pressure in Viscous Compressible Liquid

    Institute of Scientific and Technical Information of China (English)

    A. P. Szumowski; J. Piechna

    2001-01-01

    A shock tube is used to investigate the bubble dynamics under sudden decrease of ambient pressure. Both the oscillating and monotonously growing bubbles were simultaneously observed. Theoretical approach is based on Considering the linear approximation of these equations for the quasiequilibrium state, two critical Weber numbers are defined. They enable one to predict the following modes of the bubble expansion: (i) unbounded growth, (ii) asymptotic growth to limited volume and (iii) attenuated oscillations, depending on the pressure force,viscosity and compressibility of the liquid.

  16. Influence of ambient air pressure on impact pressure caused by breaking waves

    NARCIS (Netherlands)

    Moutzouris, C.

    1979-01-01

    Engineers are interested in the dynamics of the interface waterstructure. In case of breaking of water waves on a structure high positive and sometimes negative pressures of very short duration occur. Not only the maxima and minima of the pressures on the structure are important to a designing engin

  17. Ambient Vibration Testing for Story Stiffness Estimation of a Heritage Timber Building

    Directory of Open Access Journals (Sweden)

    Kyung-Won Min

    2013-01-01

    Full Text Available This paper investigates dynamic characteristics of a historic wooden structure by ambient vibration testing, presenting a novel estimation methodology of story stiffness for the purpose of vibration-based structural health monitoring. As for the ambient vibration testing, measured structural responses are analyzed by two output-only system identification methods (i.e., frequency domain decomposition and stochastic subspace identification to estimate modal parameters. The proposed methodology of story stiffness is estimation based on an eigenvalue problem derived from a vibratory rigid body model. Using the identified natural frequencies, the eigenvalue problem is efficiently solved and uniquely yields story stiffness. It is noteworthy that application of the proposed methodology is not necessarily confined to the wooden structure exampled in the paper.

  18. Ambient vibration testing for story stiffness estimation of a heritage timber building.

    Science.gov (United States)

    Min, Kyung-Won; Kim, Junhee; Park, Sung-Ah; Park, Chan-Soo

    2013-01-01

    This paper investigates dynamic characteristics of a historic wooden structure by ambient vibration testing, presenting a novel estimation methodology of story stiffness for the purpose of vibration-based structural health monitoring. As for the ambient vibration testing, measured structural responses are analyzed by two output-only system identification methods (i.e., frequency domain decomposition and stochastic subspace identification) to estimate modal parameters. The proposed methodology of story stiffness is estimation based on an eigenvalue problem derived from a vibratory rigid body model. Using the identified natural frequencies, the eigenvalue problem is efficiently solved and uniquely yields story stiffness. It is noteworthy that application of the proposed methodology is not necessarily confined to the wooden structure exampled in the paper.

  19. Estimation of ambient PM2.5 concentrations in Maryland and verification by measured values.

    Science.gov (United States)

    Walsh, Kenneth; Sherwell, John

    2002-10-01

    In 1997, Maryland had no available ambient Federal Reference Method data on particulate matter less than 2.5 microm in aerodynamic diameter (PM23), but did have annual ambient data for PM smaller than 10 microm (PM10) at 24 sites. The PM10 data were analyzed in conjunction with local annual and seasonal zip-code-level emission inventories and with speciated PM2.5 data from four nearby monitors in the IMPROVE network (located in the national parks, wildlife refuges, and wilderness areas) in an effort to estimate annual average and seasonal high PM2.5 concentrations at the 24 PM10 monitor sites operating from 1992 to 1996. All seasonal high concentrations were estimated to be below the 24-hr PM2.5 National Ambient Air Quality Standards (NAAQS) at the sites operating in Maryland between 1992 and 1996. The estimates also indicated that 12 monitor sites might exceed the 3-year annual average PM2.5 NAAQS of 15 microg/m3, but Maryland's air quality shows signs that it has been improving since 1992. The estimates also were compared with actual measurements after the PM2.5 monitor network was installed. The estimates were adequate for describing the chemical composition of the PM2.5, forecasting compliance status with the 24-hr and annual standards, and determining the spatial variations in PM2.5 across central Maryland.

  20. The Effect of Argon Ambient Pressure and Annealing Time on Bulk MgB2 Superconductor

    Science.gov (United States)

    Erdem, Murat; Ozturk, Ozgur; Asikuzun, Elif; Kaya, Seydanur; Safran, Serap; Kilic, Ahmet; Terzioglu, Cabir

    2015-03-01

    The effects of Ar ambient pressure (vacuum, 0B, 10B and 20B) and annealing times (0.5 h and 1 h) on microstructural, superconducting and mechanical properties of bulk superconducting MgB2 are investigated. The samples are produced using the solid state reaction method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements were performed for determination of the crystal structure, and surface morphology of MgB2 samples, respectively. The superconducting properties were studied by AC magnetic susceptibility and DC resistivity measurements. Increasing the Ar pressure decreased the lattice parameters and hence the average grain size. Increasing the annealing time results in larger lattice parameters and larger grain formation. The susceptibility measurements revealed two step transition which is reminiscent of granular superconductors. The intra-grain transition temperature is determined to be 38.4 K for all samples. The inter-grain transition temperatures of 37.2 K is obtained for samples produced under Ar ambient. The samples produced under Ar ambient have better superconducting properties than the ones produced in vacuum. Increasing the annealing time under vacuum further decreases the superconducting properties probably due to Mg loss. This research is supported by Kastamonu University Scientific Research Projects Coordination Department under the Grant No. KUBAP-03/2012-03.

  1. Exploring novel phases of Cd-O system at ambient pressure

    Science.gov (United States)

    Zaoui, A.; Ferhat, M.

    2017-02-01

    First-principles evolutionary searches are used to explore stable Cd-O compounds at ambient pressure. Besides the well-known rock-salt CdO, a new cubic thermodynamically stable phase CdO2 with space group Pa3 and two metastable compounds: zinc-blende and wurtzite phases of CdO have been discovered at ambient pressure. Among these, CdO2 was successfully synthesized with perfect structural agreement to our theoretical predictions. The global stability of the well known rock-salt phase of CdO, our calculations of elastic constants and phonon dispersion curves demonstrate that the Pa3, zinc-blende and wurtzite structures are mechanically and dynamically stable. Finally, the state-of-the-art LDA-1/2 methods reveal that at ambient conditions, zinc-blende and wurtzite phases are semiconducting with a direct band gap (Γ- Γ) of 0.89 eV and 0.97 eV respectively; whereas the semiconducting cubic-Pa3 structure shows direct band gap (Γ- Γ) of ∼2.93 eV and an indirect band gap of ∼2.58 eV agreeing well with the experimental value of ∼2.4 eV.

  2. Providing Context for Ambient Particulate Matter and Estimates of Attributable Mortality.

    Science.gov (United States)

    McClellan, Roger O

    2016-09-01

    Four papers on fine particulate matter (PM2.5 ) by Anenberg et al., Fann et al., Shin et al., and Smith contribute to a growing body of literature on estimated epidemiological associations between ambient PM2.5 concentrations and increases in health responses relative to baseline notes. This article provides context for the four articles, including a historical review of provisions of the U.S. Clean Air Act as amended in 1970, requiring the setting of National Ambient Air Quality Standards (NAAQS) for criteria pollutants such as particulate matter (PM). The substantial improvements in both air quality for PM and population health as measured by decreased mortality rates are illustrated. The most recent revision of the NAAQS for PM2.5 in 2013 by the Environmental Protection Agency distinguished between (1) uncertainties in characterizing PM2.5 as having a causal association with various health endpoints, and as all-cause mortality, and (2) uncertainties in concentration--excess health response relationships at low ambient PM2.5 concentrations below the majority of annual concentrations studied in the United States in the past. In future reviews, and potential revisions, of the NAAQS for PM2.5 , it will be even more important to distinguish between uncertainties in (1) characterizing the causal associations between ambient PM2.5 concentrations and specific health outcomes, such as all-source mortality, irrespective of the concentrations, (2) characterizing the potency of major constituents of PM2.5 , and (3) uncertainties in the association between ambient PM2.5 concentrations and specific health outcomes at various ambient PM2.5 concentrations. The latter uncertainties are of special concern as ambient PM2.5 concentrations and health morbidity and mortality rates approach background or baseline rates.

  3. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement

    Science.gov (United States)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi

    2006-05-01

    Mechanical load to the blood vessel wall, such as shear stress and pressure, which occurs in blood flow dynamics, contribute greatly to plaque rupture in arteriosclerosis and to biochemical activation of endothelial cells. Therefore, noninvasive estimations of these mechanical loads are able to provide useful information for the prevention of vascular diseases. Although the pressure is the dominant component of mechanical load, for practical purposes, the pressure gradient is also often important. So far, we have investigated the estimation of the kinematic viscosity coefficient using a combination of the Navier-Stokes equations and ultrasonic velocity measurement. In this paper, a method for pressure gradient estimation using the estimated kinematic viscosity coefficient is proposed. The validity of the proposed method was investigated on the basis of the analysis with the data obtained by computer simulation and a flow phantom experiment. These results revealed that the proposed method can provide a valid estimation of the pressure gradient.

  4. Ambient-Pressure X-ray Photoelectron Spectroscopy through Electron Transparent Graphene Membranes

    CERN Document Server

    Kraus, Jurgen; Gunther, Sebastian; Gregoratti, Luca; Amati, Matteo; Kiskinova, Maya; Yulaev, Alexander; Vlassiouk, Ivan; Kolmakov, Andrei

    2014-01-01

    Photoelectron spectroscopy (PES) and microscopy are highly demanded for exploring morphologically complex solid-gas and solid-liquid interfaces under realistic conditions, but the very small electron mean free path inside the dense media imposes serious experimental challenges. Currently, near ambient pressure PES is conducted using sophisticated and expensive electron energy analyzers coupled with differentially pumped electron lenses. An alternative economical approach proposed in this report uses ultrathin graphene membranes to isolate the ambient sample environment from the PES detection system. We demonstrate that the graphene membrane separating windows are both mechanically robust and sufficiently transparent for electrons in a wide energy range to allow PES of liquid and gaseous water. The reported proof-of-principle experiments also open a principal possibility to probe vacuum-incompatible toxic or reactive samples enclosed inside the hermetic environmental cells.

  5. Collaborative Processing of Wearable and Ambient Sensor System for Blood Pressure Monitoring

    Science.gov (United States)

    Nakamura, Masayuki; Nakamura, Jiro; Lopez, Guillaume; Shuzo, Masaki; Yamada, Ichiro

    2011-01-01

    This paper describes wireless wearable and ambient sensors that cooperate to monitor a person’s vital signs such as heart rate and blood pressure during daily activities. Each wearable sensor is attached on different parts of the body. The wearable sensors require a high sampling rate and time synchronization to provide a precise analysis of the received signals. The trigger signal for synchronization is provided by the ambient sensors, which detect the user’s presence. The Bluetooth and IEEE 802.15.4 wireless technologies are used for real-time sensing and time synchronization. Thus, this wearable health-monitoring sensor response is closely related to the context in which it is being used. Experimental results indicate that the system simultaneously provides information about the user’s location and vital signs, and the synchronized wearable sensors successfully measures vital signs with a 1 ms resolution. PMID:22163984

  6. Collaborative Processing of Wearable and Ambient Sensor System for Blood Pressure Monitoring

    Directory of Open Access Journals (Sweden)

    Ichiro Yamada

    2011-06-01

    Full Text Available This paper describes wireless wearable and ambient sensors that cooperate to monitor a person’s vital signs such as heart rate and blood pressure during daily activities. Each wearable sensor is attached on different parts of the body. The wearable sensors require a high sampling rate and time synchronization to provide a precise analysis of the received signals. The trigger signal for synchronization is provided by the ambient sensors, which detect the user’s presence. The Bluetooth and IEEE 802.15.4 wireless technologies are used for real-time sensing and time synchronization. Thus, this wearable health-monitoring sensor response is closely related to the context in which it is being used. Experimental results indicate that the system simultaneously provides information about the user’s location and vital signs, and the synchronized wearable sensors successfully measures vital signs with a 1 ms resolution.

  7. Development of a low cost method to estimate the seismic signature of a geothermal field form ambient noise analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Tibuleac, Ileana [Univ. of Nevada, Reno, NV (United States)

    2016-06-30

    A new, cost effective and non-invasive exploration method using ambient seismic noise has been tested at Soda Lake, NV, with promising results. The material included in this report demonstrates that, with the advantage of initial S-velocity models estimated from ambient noise surface waves, the seismic reflection survey, although with lower resolution, reproduces the results of the active survey when the ambient seismic noise is not contaminated by strong cultural noise. Ambient noise resolution is less at depth (below 1000m) compared to the active survey. In general, the results are promising and useful information can be recovered from ambient seismic noise, including dipping features and fault locations.

  8. A novel approach to scanning electron microscopy at ambient atmospheric pressure.

    Science.gov (United States)

    Ominami, Yusuke; Kawanishi, Shinsuke; Ushiki, Tatsuo; Ito, Sukehiro

    2015-04-01

    Scanning electron microscopy (SEM) for observing samples at ambient atmospheric pressure is introduced in this study. An additional specimen chamber with a small window is inserted in the main specimen chamber, and the window is separated with a thin membrane or diaphragm allowing electron beam propagation. Close proximity of the sample to the membrane enables the detection of back-scattered electrons sufficient for imaging. In addition to the empirical imaging data, a probability analysis of the un-scattered fraction of the incident electron beam further supports the feasibility of atmospheric SEM imaging over a controlled membrane-sample distance.

  9. Effect of ambient nitrogen pressure on the formation and spatio-temporal behaviour of C2 and CN

    Indian Academy of Sciences (India)

    Archana Kushwaha; R K Thareja

    2010-12-01

    We report the effect of ambient gas on the formation as well as propagation behaviour of ablated species C2 and CN within the carbon plasma created by focussing a high-power Nd:YAG ( = 1064 nm) laser onto the rotating graphite target in the nitrogen ambient. The formation of C2 takes place earlier as well as nearer the target compared to that of CN which forms later and far from the target, in 1.2 mbar pressure of N2 gas. Peak arrival time vs. nitrogen gas pressure plot shows a shock wave-like dependence ∝ in the pressure range 1.2–120 mbar (collisional regime) which indicates plume confinement with increases in ambient pressure. At higher pressure, thermalization takes place.

  10. Comparison of visual acuity estimates using three different letter charts under two ambient room illuminations

    Directory of Open Access Journals (Sweden)

    Ai-Hong Chen

    2012-01-01

    Full Text Available Background: Visual acuity is an essential estimate to assess ability of the visual system and is used as an indicator of ocular health status. Aim: The aim of this study is to investigate the consistency of acuity estimates from three different clinical visual acuity charts under two levels of ambient room illumination. Materials and Methods: This study involved thirty Malay university students aged between 19 and 23 years old (7 males, 23 females, with their spherical refractive error ranging between plano and −7.75D, astigmatism ranging from plano to −1.75D, anisometropia less than 1.00D and with no history of ocular injury or pathology. Right eye visual acuity (recorded in logMAR unit was measured with Snellen letter chart (Snellen, wall mounted letter chart (WM and projected letter chart (PC under two ambient room illuminations, room light on and room light off. Results: Visual acuity estimates showed no statistically significant difference when measured with the room light on and with the room light off (F1,372 = 0.26, P = 0.61. Post-hoc analysis with Tukey showed that visual acuity estimates were significantly different between the Snellen and PC (P = 0.009 and between Snellen and WM (P = 0.002. Conclusions: Different levels of ambient room illumination had no significant effect on visual acuity estimates. However, the discrepancies in estimates of visual acuity noted in this study were purely due to the type of letter chart used.

  11. Phase formation of superconducting MgB2 at ambient pressure

    Indian Academy of Sciences (India)

    A Talapatra; S K Bandyopadhyay; Pintu Sen; A Sarkar; P Barat

    2004-10-01

    MgB2 superconductor has been synthesized using a simple technique at ambient pressure. The synthesis was carried out in helium atmosphere over a wide range of temperatures. Magnesium was employed in excess to the stoichiometry to prevent the decomposition of MgB2. Samples of MgB2 thus prepared have been almost free from MgO as compared to other methods. Resistivities of the samples are quite low with residual resistivity ratio (RRR) of around 3. c ( = 0) is 38.2–38.5 K with c of 0.6–1.0 K. Comparative studies of various methods of low pressure synthesis have been presented.

  12. Influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma

    CERN Document Server

    Duluard, C Y; Hubert, J; Reniers, F

    2016-01-01

    The influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma has been investigated experimentally. Spatially resolved mass spectrometry and laser induced fluorescence on OH radicals were used to estimate the intrusion of air in between the plasma torch and the substrate as a function of the torch-to-substrate separation distance. No air is detected, within the limits of measurement uncertainties, for separation distances smaller than 5 mm. For larger distances, the effect of ambient air can no longer be neglected, and radial gradients in the concentrations of species appear. The Ar 4p population, determined through absolute optical emission spectroscopy, is seen to decrease with separation distance, whereas a rise in emission from the N2(C--B) system is measured. The observed decay in Ar 4p and N2(C) populations for separation distances greater than 9mm is partly assigned to the increasing collisional quenching rate by N2 and O2 molecules from the entrained air....

  13. Estimating the effects of ambient conditions on the performance of UVGI air cleaners

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Josephine; Bahnfleth, William; Freihaut, James [Indoor Environment Center, Department of Architectural Engineering, The Pennsylvania State University, University Park, PA (United States)

    2009-07-15

    Ultraviolet germicidal irradiation (UVGI) uses UVC radiation produced by low pressure mercury vapor lamps to control biological air contaminants. Ambient air velocity and temperature have a strong effect on lamp output by influencing the lamp surface cold spot temperature. In-duct UVGI systems are particularly susceptible to ambient effects due to the range of velocity and temperature conditions they may experience. An analytical model of the effect of ambient conditions on lamp surface temperature was developed for three common lamp types in cross flow from a convective-radiative energy balance assuming constant surface temperature. For one lamp type, a single tube standard output lamp, UVC output and cold spot temperature data were obtained under typical in-duct operating conditions. Over an ambient temperature range of 10-32.2 C and an air velocity range of 0-3.25 m/s, measured cold spot temperature varied from 12.7 to 41.9 C and measured lamp output varied by 68% of maximum. Surface temperatures predicted by the heat transfer model were 6-17 C higher than corresponding measured cold spot temperatures, but were found to correlate well with cold spot temperature via a two-variable linear regression. When corrected using this relationship, the simple model predicted the cold spot temperature within 1 C and lamp UVC output within {+-}5%. To illustrate its practical use, the calibrated lamp model was employed in a simulation of the control of a contaminant in a single-zone ventilation system by an in-duct UVGI device. In this example, failure to account for the impact of ambient condition effects resulted in under-prediction of average space concentration by approximately 20% relative to a constant output system operating at maximum UVC output. (author)

  14. Lung diffusing capacity for nitric oxide at lowered and raised ambient pressures.

    Science.gov (United States)

    Linnarsson, Dag; Hemmingsson, Tryggve E; Frostell, Claes; Van Muylem, Alain; Kerckx, Yannick; Gustafsson, Lars E

    2013-12-01

    Lung diffusing capacity for NO (DLNO) was determined in eight subjects at ambient pressures of 505, 1015, and 4053hPa (379, 761 and 3040mmHg) as they breathed normoxic gases. Mean values were 116.9±11.1 (SEM), 113.4±11.1 and 99.3±10.1mlmin(-1)hPa(-1)at 505, 1015, and 4053hPa, with a 13% difference between the two higher pressures (P=0.017). The data were applied to a model with two serially coupled conductances; the gas phase (DgNO, variable with pressure), and the alveolo-capillary membrane (DmNO, constant). The data fitted the model well and we conclude that diffusive transport of NO in the peripheral lung is inversely related to gas density. At normal pressure DmNO was approximately 5% larger than DLNO, suggesting that the Dg factor then is not negligible. We also conclude that the density of the breathing gas is likely to impact the backdiffusion of naturally formed NO from conducting airways to the alveoli.

  15. Pressure induced ionic-superionic transition in silver iodide at ambient temperature.

    Science.gov (United States)

    Han, Y H; Wang, H B; Troyan, I A; Gao, C X; Eremets, M I

    2014-01-28

    Silver iodide (AgI-V) is an archetypical ionic compound for studying the formation mechanism of a superionic state. Previous studies have proven that superionic AgI with high ionic conductivity greater than 0.1 Ω(-1)cm(-1) could only be obtained at high temperatures. We show in this paper that high pressure could also induce the superionic state in AgI even at ambient temperature. Using electrochemical impedance spectroscopy, we investigated Ag(+) ions diffusing in rock-salt structured AgI-III and KOH-type AgI-V under high pressures and directly observed the superionic state in AgI-V. The diffusion coefficient of AgI-V is ∼3.4 × 10(-4)-8.6 × 10(-4) cm(2)/s in the investigated pressure range of 12-17 GPa, comparable with those of superionic α-AgI and AgI-III'. By analyzing the half infinite length Warburg diffusion process, two parameters α and β, which closely relate to the disordered state of Ag(+) ions, have been determined and it was suggested that Ag(+) ions in AgI-V become disordered. The ionic conductivity of AgI-V is three orders of magnitude higher than that of AgI-III, and has reached around 0.1 Ω(-1)cm(-1). Evidence for all three, the diffusion coefficient, α and β, and conductivity have proven that AgI-V is a superionic conductor at ambient temperature.

  16. Investigating the efficacy of subharmonic aided pressure estimation for portal vein pressures and portal hypertension monitoring.

    Science.gov (United States)

    Dave, Jaydev K; Halldorsdottir, Valgerdur G; Eisenbrey, John R; Merton, Daniel A; Liu, Ji-Bin; Zhou, Jian-Hua; Wang, Hsin-Kai; Park, Suhyun; Dianis, Scott; Chalek, Carl L; Lin, Feng; Thomenius, Kai E; Brown, Daniel B; Forsberg, Flemming

    2012-10-01

    The efficacy of using subharmonic emissions from Sonazoid microbubbles (GE Healthcare, Oslo, Norway) to track portal vein pressures and pressure changes was investigated in 14 canines using either slow- or high-flow models of portal hypertension (PH). A modified Logiq 9 scanner (GE Healthcare, Milwaukee, WI, USA) operating in subharmonic mode (f(transmit): 2.5 MHz, f(receive): 1.25 MHz) was used to collect radiofrequency data at 10-40% incident acoustic power levels with 2-4 transmit cycles (in triplicate) before and after inducing PH. A pressure catheter (Millar Instruments, Inc., Houston, TX, USA) provided reference portal vein pressures. At optimum insonification, subharmonic signal amplitude changes correlated with portal vein pressure changes; r ranged from -0.82 to -0.94 and from -0.70 to -0.73 for PH models considered separately or together, respectively. The subharmonic signal amplitudes correlated with absolute portal vein pressures (r: -0.71 to -0.79). Statistically significant differences between subharmonic amplitudes, before and after inducing PH, were noted (p ≤ 0.01). Portal vein pressures estimated using subharmonic aided pressure estimation did not reveal significant differences (p > 0.05) with respect to the pressures obtained using the Millar pressure catheter. Subharmonic-aided pressure estimation may be useful clinically for portal vein pressure monitoring.

  17. Tyre pressure monitoring using a dynamical model-based estimator

    Science.gov (United States)

    Reina, Giulio; Gentile, Angelo; Messina, Arcangelo

    2015-04-01

    In the last few years, various control systems have been investigated in the automotive field with the aim of increasing the level of safety and stability, avoid roll-over, and customise handling characteristics. One critical issue connected with their integration is the lack of state and parameter information. As an example, vehicle handling depends to a large extent on tyre inflation pressure. When inflation pressure drops, handling and comfort performance generally deteriorate. In addition, it results in an increase in fuel consumption and in a decrease in lifetime. Therefore, it is important to keep tyres within the normal inflation pressure range. This paper introduces a model-based approach to estimate online tyre inflation pressure. First, basic vertical dynamic modelling of the vehicle is discussed. Then, a parameter estimation framework for dynamic analysis is presented. Several important vehicle parameters including tyre inflation pressure can be estimated using the estimated states. This method aims to work during normal driving using information from standard sensors only. On the one hand, the driver is informed about the inflation pressure and he is warned for sudden changes. On the other hand, accurate estimation of the vehicle states is available as possible input to onboard control systems.

  18. Noninvasive LV pressure estimation using subharmonic emissions from microbubbles.

    Science.gov (United States)

    Dave, Jaydev K; Halldorsdottir, Valgerdur G; Eisenbrey, John R; Raichlen, Joel S; Liu, Ji-Bin; McDonald, Maureen E; Dickie, Kris; Wang, Shumin; Leung, Corina; Forsberg, Flemming

    2012-01-01

    To develop a new noninvasive approach to quantify left ventricular (LV) pressures using subharmonic emissions from microbubbles, an ultrasound scanner was used in pulse inversion grayscale mode; unprocessed radiofrequency data were obtained with pulsed wave Doppler from the aorta and/or LV during Sonazoid infusion. Subharmonic data (in dB) were extracted and processed. Calibration factor (mm Hg/dB) from the aortic pressure was used to estimate LV pressures. Errors ranged from 0.19 to 2.50 mm Hg when estimating pressures using the aortic calibration factor, and were higher (0.64 to 8.98 mm Hg) using a mean aortic calibration factor. Subharmonic emissions from ultrasound contrast agents have the potential to noninvasively monitor LV pressures.

  19. The effect of ambient pressure on ejecta sheets from free-surface ablation

    KAUST Repository

    Marston, J. O.

    2016-04-16

    We present observations from an experimental study of the ablation of a free liquid surface promoted by a focused laser pulse, causing a rapid discharge of liquid in the form of a very thin conical-shaped sheet. In order to capture the dynamics, we employ a state-of-the-art ultra-high-speed video camera capable of capturing events at (Formula presented.) fps with shutter speeds down to 20 ns, whereby we were able to capture not only the ejecta sheet, but also the shock wave, emerging at speeds of up to 1.75 km/s, which is thus found to be hypersonic (Mach 5). Experiments were performed at a range of ambient pressures in order to study the effect of air drag on the evolution of the sheet, which was always observed to dome over, even at pressures as low as 3.8 kPa. At reduced pressures, the extended sheet evolution led to the formation of interference fringe patterns from which, by comparison with the opening speed of rupture, we were able to determine the ejecta thickness. © 2016, Springer-Verlag Berlin Heidelberg.

  20. Synthesis of ammonia directly from air and water at ambient temperature and pressure.

    Science.gov (United States)

    Lan, Rong; Irvine, John T S; Tao, Shanwen

    2013-01-01

    The N≡N bond (225 kcal mol⁻¹) in dinitrogen is one of the strongest bonds in chemistry therefore artificial synthesis of ammonia under mild conditions is a significant challenge. Based on current knowledge, only bacteria and some plants can synthesise ammonia from air and water at ambient temperature and pressure. Here, for the first time, we report artificial ammonia synthesis bypassing N₂ separation and H₂ production stages. A maximum ammonia production rate of 1.14 × 10⁻⁵ mol m⁻² s⁻¹ has been achieved when a voltage of 1.6 V was applied. Potentially this can provide an alternative route for the mass production of the basic chemical ammonia under mild conditions. Considering climate change and the depletion of fossil fuels used for synthesis of ammonia by conventional methods, this is a renewable and sustainable chemical synthesis process for future.

  1. Optimized Synthesis of Carbon Aerogels via Ambient Pressure Drying Process as Electrode for Supercapacitors

    Institute of Scientific and Technical Information of China (English)

    YUAN Lei; CHANG Lijuan; FU Zhibing; YANG Xi; JIAO Xingli; TANG Yongjian; LIU Xichuan; WANG Chaoyang

    2015-01-01

    Carbon aerogels were synthesized via ambient pressure drying process using resorcinol-formaldehyde as precursor and P123 to strengthen their skeletons. CO2 activation technology was implemented to improve surface areas and adjust pore size distribution. The synthesis process was optimized, and the morphology, structure, adsorption properties and electrochemical behavior of different samples were characterized. The CO2-activated samples achieved a high specific capacitance of 129.2 F/g in 6 M KOH electrolytes at the current density of 1 mA/cm2 within the voltage range of 0-0.8 V. The optimized activation temperature and duration were determined to be 950℃and 4 h, respectively.

  2. Multipole Electrodynamic Ion Trap Geometries for Microparticle Confinement under Standard Ambient Temperature and Pressure Conditions

    CERN Document Server

    Mihalcea, Bogdan M; Stan, Cristina; Visan, Gina T; Ganciu, Mihai; Filinov, Vladimir E; Lapitsky, Dmitry S; Deputatova, Lidiya V; Syrovatka, Roman A

    2015-01-01

    Trapping of microparticles and aerosols is of great interest for physics and chemistry. We report microparticle trapping in multipole linear Paul trap geometries, operating under Standard Ambient Temperature and Pressure (SATP) conditions. An 8-electrode and a 12-electrode linear trap geometries have been designed and tested with an aim to achieve trapping for larger number of particles and to study microparticle dynamical stability in electrodynamic fields. We report emergence of planar and volume ordered structures of the microparticles, depending on the a.c. trapping frequency and particle specific charge ratio. The electric potential within the trap was mapped using the electrolytic tank method. Particle dynamics was simulated using a stochastic Langevin equation. We emphasize extended regions of stable trapping with respect to quadrupole traps, as well as good agreement between experiment and numerical simulations.

  3. Ceramic coating of metal by laser heat treatment at ambient pressure and temperature

    Science.gov (United States)

    Picouet, Pierre A.; McStay, Daniel; Hunter, Catherine; Tonge, Kenneth

    2000-02-01

    Initial results for a new laser based procedure to make ceramic coatings on ferrous metals are described. The procedure is performed at ambient temperature and pressure to avoid the use of a vacuum chamber. An Nd:YAG laser beam (1064 nm) coupled to a mechanical scanner is used to produce coating. The coating precursor materials are sprayed onto the metal sample before the laser-generated heat treatment. A jet of argon gas is used to avoid oxidation of the metallic substrate. The principal ingredients of the coating precursor are sodium tetraborate and a natural clay mineral. The product is a glassy ceramic. The product has been characterized by scanning electron microscopy, optical microscopy and hardness and adhesion tests. The results indicate that the surface material is a micrometric, single layer which adheres to the metal surface.

  4. Estimating methane emissions from landfills based on rainfall, ambient temperature, and waste composition: The CLEEN model.

    Science.gov (United States)

    Karanjekar, Richa V; Bhatt, Arpita; Altouqui, Said; Jangikhatoonabad, Neda; Durai, Vennila; Sattler, Melanie L; Hossain, M D Sahadat; Chen, Victoria

    2015-12-01

    Accurately estimating landfill methane emissions is important for quantifying a landfill's greenhouse gas emissions and power generation potential. Current models, including LandGEM and IPCC, often greatly simplify treatment of factors like rainfall and ambient temperature, which can substantially impact gas production. The newly developed Capturing Landfill Emissions for Energy Needs (CLEEN) model aims to improve landfill methane generation estimates, but still require inputs that are fairly easy to obtain: waste composition, annual rainfall, and ambient temperature. To develop the model, methane generation was measured from 27 laboratory scale landfill reactors, with varying waste compositions (ranging from 0% to 100%); average rainfall rates of 2, 6, and 12 mm/day; and temperatures of 20, 30, and 37°C, according to a statistical experimental design. Refuse components considered were the major biodegradable wastes, food, paper, yard/wood, and textile, as well as inert inorganic waste. Based on the data collected, a multiple linear regression equation (R(2)=0.75) was developed to predict first-order methane generation rate constant values k as functions of waste composition, annual rainfall, and temperature. Because, laboratory methane generation rates exceed field rates, a second scale-up regression equation for k was developed using actual gas-recovery data from 11 landfills in high-income countries with conventional operation. The Capturing Landfill Emissions for Energy Needs (CLEEN) model was developed by incorporating both regression equations into the first-order decay based model for estimating methane generation rates from landfills. CLEEN model values were compared to actual field data from 6 US landfills, and to estimates from LandGEM and IPCC. For 4 of the 6 cases, CLEEN model estimates were the closest to actual.

  5. Ambient pressure photoelectron spectroscopy: a new tool for surface science and nanotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Salmeron, Miquel; Salmeron, Miquel; Schlogl, Robert

    2008-03-12

    Progress in science often follows or parallels the development of new techniques. The optical microscope helped convert medicine and biology from a speculative activity in old times to today's sophisticated scientific disciplines. The telescope changed the study and interpretation of heavens from mythology to science. X-ray diffraction enabled the flourishing of solid state physics and materials science. The technique object of this review, Ambient Pressure Photoelectron Spectroscopy or APPES for short, has also the potential of producing dramatic changes in the study of liquid and solid surfaces, particularly in areas such as atmospheric, environment and catalysis sciences. APPES adds an important missing element to the host of techniques that give fundamental information, i.e., spectroscopy and microscopy, about surfaces in the presence of gases and vapors, as encountered in industrial catalysis and atmospheric environments. APPES brings electron spectroscopy into the realm of techniques that can be used in practical environments. Decades of surface science in ultra high vacuum (UHV) has shown the power of electron spectroscopy in its various manifestations. Their unique property is the extremely short elastic mean free path of electrons as they travel through condensed matter, of the order of a few atomic distances in the energy range from a few eV to a few thousand eV. As a consequence of this the information obtained by analyzing electrons emitted or scattered from a surface refers to the top first few atomic layers, which is what surface science is all about. Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Ultraviolet photoelectron spectroscopy (UPS), and other such techniques have been used for decades and provided some of the most fundamental knowledge about surface crystallography, composition and electronic structure available today. Unfortunately the high interaction cross section of

  6. Bayesian fusion algorithm for improved oscillometric blood pressure estimation.

    Science.gov (United States)

    Forouzanfar, Mohamad; Dajani, Hilmi R; Groza, Voicu Z; Bolic, Miodrag; Rajan, Sreeraman; Batkin, Izmail

    2016-11-01

    A variety of oscillometric algorithms have been recently proposed in the literature for estimation of blood pressure (BP). However, these algorithms possess specific strengths and weaknesses that should be taken into account before selecting the most appropriate one. In this paper, we propose a fusion method to exploit the advantages of the oscillometric algorithms and circumvent their limitations. The proposed fusion method is based on the computation of the weighted arithmetic mean of the oscillometric algorithms estimates, and the weights are obtained using a Bayesian approach by minimizing the mean square error. The proposed approach is used to fuse four different oscillometric blood pressure estimation algorithms. The performance of the proposed method is evaluated on a pilot dataset of 150 oscillometric recordings from 10 subjects. It is found that the mean error and standard deviation of error are reduced relative to the individual estimation algorithms by up to 7 mmHg and 3 mmHg in estimation of systolic pressure, respectively, and by up to 2 mmHg and 3 mmHg in estimation of diastolic pressure, respectively.

  7. High performance PEMFC stack with open-cathode at ambient pressure and temperature conditions

    Energy Technology Data Exchange (ETDEWEB)

    Santa Rosa, D.T.; Pinto, D.G.; Silva, V.S. [SRE - Solucoes Racionais de Energia, S.A., Poligono Industrial do Alto do Ameal, Ramalhal (Portugal); Silva, R.A.; Rangel, C.M. [INETI, Unidade de Electroquimica de Materiais, Lisboa (Portugal)

    2007-12-15

    An open-air cathode proton exchange membrane fuel cell (PEMFC) was developed. This paper presents a study of the effect of several critical operating conditions on the performance of an 8-cell stack. The studied operating conditions such as cell temperature, air flow rate and hydrogen pressure and flow rate were varied in order to identify situations that could arise when the PEMFC stack is used in low-power portable PEMFC applications. The stack uses an air fan in the edge of the cathode manifolds, combining high stoichiometric oxidant supply and stack cooling purposes. In comparison with natural convection air-breathing stacks, the air dual-function approach brings higher stack performances, at the expense of having a lower use of the total stack power output. Although improving the electrochemical reactions kinetics and decreasing the polarization effects, the increase of the stack temperature lead to membrane excessive dehydration (loss of sorbed water), increasing the ohmic resistance of the stack (lower performance). The results show that the stack outputs a maximum power density of 310mW/cm{sup 2} at 790mA/cm{sup 2} when operating at ambient temperature, atmospheric air pressure, self-humidifying, air fan voltage at 5.0 V and 250 mbar hydrogen relative pressure. For the studied range of hydrogen relative pressure (150-750 mbar), it is found that the stack performance is practically not affected by this operation condition, although a slightly higher power output for 150 mbar was observed. On the other hand, it is found that the stack performance increases appreciably when operated with forced air convection instead of natural convection. Finally, the continuous fuel flow operation mode does not improve the stack performance in comparison with the hydrogen dead-end mode, in spite of being preferable to operate the stack with hydrogen flow rates above 0.20 l/min. (author)

  8. Stripe order in La2-xBaxCuO4 at ambient and high pressure.

    Science.gov (United States)

    Huecker, M.; Wen, J. S.; Xu, Z. J.; Gu, G. D.; Tranquada, J. M.; Zimmermann, M. V.

    2009-03-01

    The pronounced stability of the charge and spin stripe order in La2-xBaxCuO4 at x=1/8 doping still is a poorly understood peculiarity. A combination of electronic and structural interactions is likely, however it has been difficult to clearly separate the involved mechanisms. One approach is to explore how stripe order fades away for dopings x !=1/8. We have performed high energy (100 keV) x-ray diffraction and static magnetization experiments on single crystals between x=0.095 and 0.155. To our surprise, at ambient pressure stripes exist in a much broader range of doping around x=1/8 than expected. In the underdoped region charge stripe order always coincides with a structural transition associated with a rotation of the octahedral tilt axis. However, for x=1/8 and high pressure we have been able to show that stripe order also occurs in the absence of this structural phase, which motivates us to discuss stripes in terms of an electronic liquid crystal phase.

  9. Ambient pressure proton transfer mass spectrometry: detection of amines and ammonia.

    Science.gov (United States)

    Hanson, D R; McMurry, P H; Jiang, J; Tanner, D; Huey, L G

    2011-10-15

    An instrument to detect gaseous amines and ammonia is described, and representative data from an urban site and a laboratory setting are presented. The instrument, an Ambient pressure Proton transfer Mass Spectrometer (AmPMS), consists of a chemical ionization and drift region at atmospheric pressure coupled to a standard quadrupole mass spectrometer. Calibrations show that AmPMS sensitivity is good for amines, and AmPMS backgrounds were suitably determined by diverting sampled air through a catalytic converter. In urban air at a site in Atlanta, amines were detected at subpptv levels for methyl and dimethyl amine which were generally at a low abundance of ammonia were high, and data are very limited for these species. Improvements in detecting amines and ammonia from a smog chamber were evident due to improvements in AmPMS background determination; notably dimethyl amine and its OH oxidation products were followed along with impurity ammonia and other species. Future work will focus on accurate calibration standards and on improving the sample gas inlet.

  10. Cuffless differential blood pressure estimation using smart phones.

    Science.gov (United States)

    Chandrasekaran, Vikram; Dantu, Ram; Jonnada, Srikanth; Thiyagaraja, Shanti; Subbu, Kalyan Pathapati

    2013-04-01

    Smart phones today have become increasingly popular with the general public for their diverse functionalities such as navigation, social networking, and multimedia facilities. These phones are equipped with high-end processors, high-resolution cameras, and built-in sensors such as accelerometer, orientation-sensor, and light-sensor. According to comScore survey, 26.2% of U.S. adults use smart phones in their daily lives. Motivated by this statistic and the diverse capability of smart phones, we focus on utilizing them for biomedical applications. We present a new application of the smart phone with its built-in camera and microphone replacing the traditional stethoscope and cuff-based measurement technique, to quantify vital signs such as heart rate and blood pressure. We propose two differential blood pressure estimating techniques using the heartbeat and pulse data. The first method uses two smart phones whereas the second method replaces one of the phones with a customized external microphone. We estimate the systolic and diastolic pressure in the two techniques by computing the pulse pressure and the stroke volume from the data recorded. By comparing the estimated blood pressure values with those measured using a commercial blood pressure meter, we obtained encouraging results of 95-100% accuracy.

  11. UHV and Ambient Pressure XPS: Potentials for Mg, MgO, and Mg(OH)2 Surface Analysis

    Science.gov (United States)

    Head, Ashley R.; Schnadt, Joachim

    2016-12-01

    The surface sensitivity of x-ray photoelectron spectroscopy (XPS) has positioned the technique as a routine analysis tool for chemical and electronic structure information. Samples ranging from ideal model systems to industrial materials can be analyzed. Instrumentational developments in the past two decades have popularized ambient pressure XPS, with pressures in the tens of mbar now commonplace. Here, we briefly review the technique, including a discussion of developments that allow data collection at higher pressures. We illustrate the information XPS can provide by using examples from the literature, including MgO studies. We hope to illustrate the possibilities of ambient pressure XPS to Mg, MgO, and Mg(OH)2 systems, both in fundamental and applied studies.

  12. Reactor Design for CO2 Photo-Hydrogenation toward Solar Fuels under Ambient Temperature and Pressure

    Directory of Open Access Journals (Sweden)

    Chun-Ying Chen

    2017-02-01

    Full Text Available Photo-hydrogenation of carbon dioxide (CO2 is a green and promising technology and has received much attention recently. This technique could convert solar energy under ambient temperature and pressure into desirable and sustainable solar fuels, such as methanol (CH3OH, methane (CH4, and formic acid (HCOOH. It is worthwhile to mention that this direction can not only potentially depress atmospheric CO2, but also weaken dependence on fossil fuel. Herein, 1 wt % Pt/CuAlGaO4 photocatalyst was successfully synthesized and fully characterized by ultraviolet-visible light (UV-vis spectroscopy, X-ray diffraction (XRD, Field emission scanning electron microscopy using energy dispersive spectroscopy analysis (FE-SEM/EDS, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and Brunauer-Emmett-Teller (BET, respectively. Three kinds of experimental photo-hydrogenation of CO2 in the gas phase, liquid phase, and gas-liquid phase, correspondingly, were conducted under different H2 partial pressures. The remarkable result has been observed in the gas-liquid phase. Additionally, increasing the partial pressure of H2 would enhance the yield of product. However, when an extra amount of H2 is supplied, it might compete with CO2 for occupying the active sites, resulting in a negative effect on CO2 photo-hydrogenation. For liquid and gas-liquid phases, CH3OH is the major product. Maximum total hydrocarbons 8.302 µmol·g−1 is achieved in the gas-liquid phase.

  13. Compensation for the Effects of Ambient Conditions on the Calibration of Multi-Capillary Pressure Drop Standards

    Directory of Open Access Journals (Sweden)

    Colard S

    2014-12-01

    Full Text Available Cigarette draw resistance and filter pressure drop (PD are both major physical parameters for the tobacco industry. Therefore these parameters must be measured reliably. For these measurements, specific equipment calibrated with PD transfer standards is used. Each transfer standard must have a known and stable PD value, such standards usually being composed of several capillary tubes associated in parallel. However, PD values are modified by ambient conditions during calibration of such standards, i.e. by temperature and relative humidity (RH of air, and atmospheric pressure. In order to reduce the influence of these ambient factors, a simplified model was developed for compensating the effects of ambient conditions on the calibration of multi-capillary PD standards.

  14. Comparison of exposure estimation methods for air pollutants: ambient monitoring data and regional air quality simulation.

    Science.gov (United States)

    Bravo, Mercedes A; Fuentes, Montserrat; Zhang, Yang; Burr, Michael J; Bell, Michelle L

    2012-07-01

    Air quality modeling could potentially improve exposure estimates for use in epidemiological studies. We investigated this application of air quality modeling by estimating location-specific (point) and spatially-aggregated (county level) exposure concentrations of particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM(2.5)) and ozone (O(3)) for the eastern U.S. in 2002 using the Community Multi-scale Air Quality (CMAQ) modeling system and a traditional approach using ambient monitors. The monitoring approach produced estimates for 370 and 454 counties for PM(2.5) and O(3), respectively. Modeled estimates included 1861 counties, covering 50% more population. The population uncovered by monitors differed from those near monitors (e.g., urbanicity, race, education, age, unemployment, income, modeled pollutant levels). CMAQ overestimated O(3) (annual normalized mean bias=4.30%), while modeled PM(2.5) had an annual normalized mean bias of -2.09%, although bias varied seasonally, from 32% in November to -27% in July. Epidemiology may benefit from air quality modeling, with improved spatial and temporal resolution and the ability to study populations far from monitors that may differ from those near monitors. However, model performance varied by measure of performance, season, and location. Thus, the appropriateness of using such modeled exposures in health studies depends on the pollutant and metric of concern, acceptable level of uncertainty, population of interest, study design, and other factors.

  15. Technology qualification of an ambient pressure subsea cryogenic pipeline for offshore LNG loading and receiving terminals

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Afzal; Viteri, Martha; D' Angelo, Luis [Det Norske Veritas (DNV), Rio de Janeiro, RJ (Brazil); Prescott, Neal; Zhang, Jeff [Fluor Corporation, Irving, TX (Brazil)

    2009-07-01

    A project that deploys new technologies need to be confident that the technology can be implemented successfully and will perform reliably as designed. New technology is critical to industry, especially where such technology is a project enable without the existence of a backup solution, but also for projects where such technologies bring potential benefits such as technical, economic, schedule, and environmental improvements. DNV developed and has been implementing for many years a systematic, risk based technology qualification process as described in DNV RP-A203, qualification procedures for new technology. One of the major objectives of a formal technology qualification process is to ensure that risks are properly addressed. The DNV process includes several levels of technology qualification and review, starting with a statement of feasibility and concluding with a Certificate of Fitness for Service. Fluor Corporation (Fluor) has developed a new subsea cryogenic pipe-in-pipe configuration for offshore LNG loading and receiving terminals. The configuration uses a highly efficient thermal nano-porous insulation in the annular space between the inner and outer pipes. This material is kept in an ambient pressure environment, which is produced through sealing by metal bulkheads. The bulkheads transfer the contraction induced axial compression load on the inner cryogenic carrier pipe to the external jacket pipe. The resulting pipeline bundle is a structural element, which addresses the thermal contraction and expansion loads without the use of expansion bellows or ultra-low thermal contraction alloys. Fluor has followed the DNV technology qualification process to achieve the defined milestones therein which culminated in DNV issuing a certificate of fitness for service. Particular focus was put on the new aspects of the design. The certificate of fitness for service for the Fluor subsea LNG pipe technology provides project management with the confidence that this

  16. Noise Model Analysis and Estimation of Effect due to Wind Driven Ambient Noise in Shallow Water

    Directory of Open Access Journals (Sweden)

    S. Sakthivel Murugan

    2011-01-01

    Full Text Available Signal transmission in ocean using water as a channel is a challenging process due to attenuation, spreading, reverberation, absorption, and so forth, apart from the contribution of acoustic signals due to ambient noises. Ambient noises in sea are of two types: manmade (shipping, aircraft over the sea, motor on boat, etc. and natural (rain, wind, seismic, etc., apart from marine mammals and phytoplanktons. Since wind exists in all places and at all time: its effect plays a major role. Hence, in this paper, we concentrate on estimating the effects of wind. Seven sets of data with various wind speeds ranging from 2.11 m/s to 6.57 m/s were used. The analysis is performed for frequencies ranging from 100 Hz to 8 kHz. It is found that a linear relationship between noise spectrum and wind speed exists for the entire frequency range. Further, we developed a noise model for analyzing the noise level. The results of the empirical data are found to fit with results obtained with the aid of noise model.

  17. Estimation procedures affect the center of pressure frequency analysis.

    Science.gov (United States)

    Vieira, T M M; Oliveira, L F; Nadal, J

    2009-07-01

    Even though frequency analysis of body sway is widely applied in clinical studies, the lack of standardized procedures concerning power spectrum estimation may provide unreliable descriptors. Stabilometric tests were applied to 35 subjects (20-51 years, 54-95 kg, 1.6-1.9 m) and the power spectral density function was estimated for the anterior-posterior center of pressure time series. The median frequency was compared between power spectra estimated according to signal partitioning, sampling rate, test duration, and detrending methods. The median frequency reliability for different test durations was assessed using the intraclass correlation coefficient. When increasing number of segments, shortening test duration or applying linear detrending, the median frequency values increased significantly up to 137%. Even the shortest test duration provided reliable estimates as observed with the intraclass coefficient (0.74-0.89 confidence interval for a single 20-s test). Clinical assessment of balance may benefit from a standardized protocol for center of pressure spectral analysis that provides an adequate relationship between resolution and variance. An algorithm to estimate center of pressure power density spectrum is also proposed.

  18. Estimation procedures affect the center of pressure frequency analysis

    Directory of Open Access Journals (Sweden)

    T.M.M. Vieira

    2009-07-01

    Full Text Available Even though frequency analysis of body sway is widely applied in clinical studies, the lack of standardized procedures concerning power spectrum estimation may provide unreliable descriptors. Stabilometric tests were applied to 35 subjects (20-51 years, 54-95 kg, 1.6-1.9 m and the power spectral density function was estimated for the anterior-posterior center of pressure time series. The median frequency was compared between power spectra estimated according to signal partitioning, sampling rate, test duration, and detrending methods. The median frequency reliability for different test durations was assessed using the intraclass correlation coefficient. When increasing number of segments, shortening test duration or applying linear detrending, the median frequency values increased significantly up to 137%. Even the shortest test duration provided reliable estimates as observed with the intraclass coefficient (0.74-0.89 confidence interval for a single 20-s test. Clinical assessment of balance may benefit from a standardized protocol for center of pressure spectral analysis that provides an adequate relationship between resolution and variance. An algorithm to estimate center of pressure power density spectrum is also proposed.

  19. Real-Time Personalized Monitoring to Estimate Occupational Heat Stress in Ambient Assisted Working

    Directory of Open Access Journals (Sweden)

    Pablo Pancardo

    2015-07-01

    Full Text Available Ambient Assisted Working (AAW is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers’ comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. Occupational heat stress (OHS happens when a worker is in an uninterrupted physical activity and in a hot environment. OHS can produce strain on the body, which leads to discomfort and eventually to heat illness and even death. Related ISO standards contain methods to estimate OHS and to ensure the safety and health of workers, but they are subjective, impersonal, performed a posteriori and even invasive. This paper focuses on the design and development of real-time personalized monitoring for a more effective and objective estimation of OHS, taking into account the individual user profile, fusing data from environmental and unobtrusive body sensors. Formulas employed in this work were taken from different domains and joined in the method that we propose. It is based on calculations that enable continuous surveillance of physical activity performance in a comfortable and healthy manner. In this proposal, we found that OHS can be estimated by satisfying the following criteria: objective, personalized, in situ, in real time, just in time and in an unobtrusive way. This enables timely notice for workers to make decisions based on objective information to control OHS.

  20. Real-Time Personalized Monitoring to Estimate Occupational Heat Stress in Ambient Assisted Working.

    Science.gov (United States)

    Pancardo, Pablo; Acosta, Francisco D; Hernández-Nolasco, José Adán; Wister, Miguel A; López-de-Ipiña, Diego

    2015-07-13

    Ambient Assisted Working (AAW) is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers' comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. Occupational heat stress (OHS) happens when a worker is in an uninterrupted physical activity and in a hot environment. OHS can produce strain on the body, which leads to discomfort and eventually to heat illness and even death. Related ISO standards contain methods to estimate OHS and to ensure the safety and health of workers, but they are subjective, impersonal, performed a posteriori and even invasive. This paper focuses on the design and development of real-time personalized monitoring for a more effective and objective estimation of OHS, taking into account the individual user profile, fusing data from environmental and unobtrusive body sensors. Formulas employed in this work were taken from different domains and joined in the method that we propose. It is based on calculations that enable continuous surveillance of physical activity performance in a comfortable and healthy manner. In this proposal, we found that OHS can be estimated by satisfying the following criteria: objective, personalized, in situ, in real time, just in time and in an unobtrusive way. This enables timely notice for workers to make decisions based on objective information to control OHS.

  1. A Novel Environmental Route to Ambient Pressure Dried Thermal Insulating Silica Aerogel via Recycled Coal Gangue

    Directory of Open Access Journals (Sweden)

    Pinghua Zhu

    2016-01-01

    Full Text Available Coal gangue, one of the main hazardous emissions of purifying coal from coalmine industry, is rich in silica and alumina. However, the recycling of the waste is normally restricted by less efficient techniques and low attractive output; the utilization of such waste is still staying lower than 15%. In this work, the silica aerogel materials were synthesized by using a precursor extracted from recycled silicon-rich coal gangue, followed by a single-step surface silylation and ambient pressure drying. A low density (~0.19 g/cm3 nanostructured aerogel with a 3D open porous microstructure and high surface area (~690 m2/g was synthesized, which presents a superior thermal insulation performance (~26.5 mW·m−1·K−1 of a plane packed of 4-5 mm granules which was confirmed by transient hot-wire method. This study offers a new facile route to the synthesis of insulating aerogel material by recycling solid waste coal gangue and presents a potential cost reduction of industrial production of silica aerogels.

  2. New ambient pressure photoemission endstation at Advanced Light Source beamline 9.3.2

    KAUST Repository

    Grass, Michael E.

    2010-01-01

    During the past decade, the application of ambient pressure photoemission spectroscopy (APPES) has been recognized as an important in situ tool to study environmental and materials science, energy related science, and many other fields. Several APPES endstations are currently under planning or development at the USA and international light sources, which will lead to a rapid expansion of this technique. The present work describes the design and performance of a new APPES instrument at the Advanced Light Source beamline 9.3.2 at Lawrence Berkeley National Laboratory. This new instrument, Scienta R4000 HiPP, is a result of collaboration between Advanced Light Source and its industrial partner VG-Scienta. The R4000 HiPP provides superior electron transmission as well as spectromicroscopy modes with 16 μm spatial resolution in one dimension and angle-resolved modes with simulated 0.5° angular resolution at 24° acceptance. Under maximum transmission mode, the electron detection efficiency is more than an order of magnitude better than the previous endstation at beamline 9.3.2. Herein we describe the design and performance of the system, which has been utilized to record spectra above 2 mbar. © 2010 American Institute of Physics.

  3. Effects of Biofuel and Variant Ambient Pressure on FlameDevelopment and Emissions of Gasoline Engine.

    Science.gov (United States)

    Hashim, Akasha; Khalid, Amir; Sapit, Azwan; Samsudin, Dahrum

    2016-11-01

    There are many technologies about exhaust emissions reduction for wide variety of spark ignition (SI) engine have been considered as the improvement throughout the combustion process. The stricter on legislation of emission and demands of lower fuel consumption needs to be priority in order to satisfy the demand of emission quality. Besides, alternative fuel such as methanol-gasoline blends is used as working fluid in this study due to its higher octane number and self-sustain concept which capable to contribute positive effect to the combustion process. The purpose of this study is to investigate the effects of methanol-gasoline fuel with different blending ratio and variant ambient pressures on flame development and emission for gasoline engine. An experimental study is carried towards to the flame development of methanol-gasoline fuel in a constant volume chamber. Schlieren optical visualization technique is a visual process that used when high sensitivity is required to photograph the flow of fluids of varying density used for captured the combustion images in the constant volume chamber and analysed through image processing technique. Apart from that, the result showed combustion burn rate increased when the percentage of methanol content in gasoline increased. Thus, high percentage of methanol-gasoline blends gave greater flame development area. Moreover, the emissions of CO, NOX and HC are performed a reduction when the percentage of methanol content in gasoline is increased. Contrarily, the emission of Carbon dioxide, CO2 is increased due to the combustion process is enhanced.

  4. Effect of ambient gas pressure on pulsed laser ablation plume dynamics and ZnTe film growth

    Energy Technology Data Exchange (ETDEWEB)

    Rouleau, C.M.; Lowndes, D.H.; Geohegan, D.B.; Allard, L.F. [Oak Ridge National Lab., TN (United States); Strauss, M.A.; Cao, S.; Pedraza, A.J. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Puretzky, A.A. [Inst. of Spectroscopy, Troitsk (Russian Federation)

    1995-12-01

    Epitaxial thin films of nitrogen-doped p-ZnTe were grown on single-crystal, semi-insulating Ga-As substrates via pulsed laser ablation of a stoichiometric ZnTe target. Both low pressure nitrogen ambients and high vacuum were used. Results of in situ reflection high energy electron diffraction (RHEED) and time-resolved ion probe measurements have been compared with ex situ Hall effect and transmission electron microscopy (TEM) measurements. A strong correlation was observed between the nature of the film`s surface during growth (2-D vs. 3-D, assessed via RHEED) and the ambient gas pressures employed during deposition. The extended defect content (assessed via cross-sectional TEM) in the region >150 mn from the film/substrate interface was found to increase with the ambient gas pressure during deposition, which could not be explained by lattice mismatch alone. At sufficiently high pressures, misoriented, columnar grains developed which were not only consistent with the RHEED observations but also were correlated with a marked decrease in Hall mobility and a slight decrease in hole concentration. Ion probe measurements, which monitored the attenuation and slowing of the ion current arriving at the substrate surface, indicated that for increasing nitrogen pressure the fast (vacuum) velocity distribution splits into a distinct fast and two collisionally-slowed components or modes. Gas controlled variations in these components mirrored trends in electrical properties and microstructural measurements.

  5. Ambient pressure photoelectron spectroscopy: a new tool for surface science and nanotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Salmeron, Miquel; Salmeron, Miquel; Schlogl, Robert

    2008-03-12

    Progress in science often follows or parallels the development of new techniques. The optical microscope helped convert medicine and biology from a speculative activity in old times to today's sophisticated scientific disciplines. The telescope changed the study and interpretation of heavens from mythology to science. X-ray diffraction enabled the flourishing of solid state physics and materials science. The technique object of this review, Ambient Pressure Photoelectron Spectroscopy or APPES for short, has also the potential of producing dramatic changes in the study of liquid and solid surfaces, particularly in areas such as atmospheric, environment and catalysis sciences. APPES adds an important missing element to the host of techniques that give fundamental information, i.e., spectroscopy and microscopy, about surfaces in the presence of gases and vapors, as encountered in industrial catalysis and atmospheric environments. APPES brings electron spectroscopy into the realm of techniques that can be used in practical environments. Decades of surface science in ultra high vacuum (UHV) has shown the power of electron spectroscopy in its various manifestations. Their unique property is the extremely short elastic mean free path of electrons as they travel through condensed matter, of the order of a few atomic distances in the energy range from a few eV to a few thousand eV. As a consequence of this the information obtained by analyzing electrons emitted or scattered from a surface refers to the top first few atomic layers, which is what surface science is all about. Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Ultraviolet photoelectron spectroscopy (UPS), and other such techniques have been used for decades and provided some of the most fundamental knowledge about surface crystallography, composition and electronic structure available today. Unfortunately the high interaction cross section of

  6. Comparative study on dihydrofolate reductases from Shewanella species living in deep-sea and ambient atmospheric-pressure environments.

    Science.gov (United States)

    Murakami, Chiho; Ohmae, Eiji; Tate, Shin-ichi; Gekko, Kunihiko; Nakasone, Kaoru; Kato, Chiaki

    2011-03-01

    To examine whether dihydrofolate reductase (DHFR) from deep-sea bacteria has undergone molecular evolution to adapt to high-pressure environments, we cloned eight DHFRs from Shewanella species living in deep-sea and ambient atmospheric-pressure environments, and subsequently purified six proteins to compare their structures, stabilities, and functions. The DHFRs showed 74-90% identity in primary structure to DHFR from S. violacea, but only 55% identity to DHFR from Escherichia coli (ecDHFR). Far-ultraviolet circular dichroism and fluorescence spectra suggested that the secondary and tertiary structures of these DHFRs were similar. In addition, no significant differences were found in structural stability as monitored by urea-induced unfolding and the kinetic parameters, K(m) and k(cat); although the DHFRs from Shewanella species were less stable and more active (2- to 4-fold increases in k(cat)/K(m)) than ecDHFR. Interestingly, the pressure effects on enzyme activity revealed that DHFRs from ambient-atmospheric species are not necessarily incompatible with high pressure, and DHFRs from deep-sea species are not necessarily tolerant of high pressure. These results suggest that the DHFR molecule itself has not evolved to adapt to high-pressure environments, but rather, those Shewanella species with enzymes capable of retaining functional activity under high pressure migrated into the deep-sea.

  7. Satellite-based Estimates of Ambient Air Pollution and Global Variations in Childhood Asthma Prevalence

    Science.gov (United States)

    Anderson, H. Ross; Butland, Barbara K.; Donkelaar, Aaron Matthew Van; Brauer, Michael; Strachan, David P.; Clayton, Tadd; van Dingenen, Rita; Amann, Marcus; Brunekreef, Bert; Cohen, Aaron; Dentener, Frank; Lai, Christopher; Lamsal, Lok N.; Martin, Randall V.

    2012-01-01

    Background: The effect of ambient air pollution on global variations and trends in asthma prevalence is unclear. Objectives: Our goal was to investigate community-level associations between asthma prevalence data from the International Study of Asthma and Allergies in Childhood (ISAAC) and satellite-based estimates of particulate matter with aerodynamic diameter prevalence of severe asthma as the outcome and multilevel models to adjust for gross national income (GNI) and center- and country-level sex, climate, and population density. We examined associations (adjusting for GNI) between air pollution and asthma prevalence over time in centers with data from ISAAC Phase One (mid-1900s) and Phase Three (2001-2003). Results: For the 13- to 14-year age group (128 centers in 28 countries), the estimated average within-country change in center-level asthma prevalence per 100 children per 10% increase in center-level PM2.5 and NO2 was -0.043 [95% confidence interval (CI): -0.139, 0.053] and 0.017 (95% CI: -0.030, 0.064) respectively. For ozone the estimated change in prevalence per parts per billion by volume was -0.116 (95% CI: -0.234, 0.001). Equivalent results for the 6- to 7-year age group (83 centers in 20 countries), though slightly different, were not significantly positive. For the 13- to 14-year age group, change in center-level asthma prevalence over time per 100 children per 10% increase in PM2.5 from Phase One to Phase Three was -0.139 (95% CI: -0.347, 0.068). The corresponding association with ozone (per ppbV) was -0.171 (95% CI: -0.275, -0.067). Conclusion: In contrast to reports from within-community studies of individuals exposed to traffic pollution, we did not find evidence of a positive association between ambient air pollution and asthma prevalence as measured at the community level.

  8. A Neural Network for Estimation of Aortic Pressure from the Radial Artery Pressure Pulse

    Science.gov (United States)

    2001-10-25

    from periphery to artery: a model based study, American Journal of Physiology, 1998,274:43, pp H1386-92 [9] C. Chen, E. Nevo , B Fetics, P Pak, F, Yin, L...36. [10] B Fetics, E Nevo , C. Chen, D Kass, Parametric model derivation of transfer function for noninvasive estimation of aortic pressure by radial

  9. Estimation of blood pressure variability from 24-hour ambulatory finger blood pressure

    NARCIS (Netherlands)

    Omboni, S.; Parati, G.; Castiglioni, P.; Rienzo, M. di; Imholz, B.P.M.; Langewouters, G.J.; Wesseling, K.H.; Mancia, G.

    1998-01-01

    Portapres is a noninvasive, beat-to-beat finger blood pressure (BP) monitor that has been shown to accurately estimate 24-hour intra-arterial BP at normal and high BPs. However, no information is available on the ability of this device to accurately track ambulatory BP variability. In 20 ambulatory

  10. Ionization Mechanism of the Ambient Pressure Pyroelectric Ion Source (APPIS) and Its Applications to Chemical Nerve Agent Detection

    OpenAIRE

    Neidholdt, Evan L.; Beauchamp, J. L.

    2009-01-01

    We present studies of the ionization mechanism operative in the ambient pressure pyroelectric ionization source (APPIS), along with applications that include detection of simulants for chemical nerve agents. It is found that ionization by APPIS occurs in the gas-phase. As the crystal is thermally cycled over a narrow temperature range, electrical discharges near the surface of the crystal produce energetic species which, through reactions with atmospheric molecules, result in reactant ions su...

  11. High-global warming potential F-gas emissions in California: comparison of ambient-based versus inventory-based emission estimates, and implications of refined estimates.

    Science.gov (United States)

    Gallagher, Glenn; Zhan, Tao; Hsu, Ying-Kuang; Gupta, Pamela; Pederson, James; Croes, Bart; Blake, Donald R; Barletta, Barbara; Meinardi, Simone; Ashford, Paul; Vetter, Arnie; Saba, Sabine; Slim, Rayan; Palandre, Lionel; Clodic, Denis; Mathis, Pamela; Wagner, Mark; Forgie, Julia; Dwyer, Harry; Wolf, Katy

    2014-01-21

    To provide information for greenhouse gas reduction policies, the California Air Resources Board (CARB) inventories annual emissions of high-global-warming potential (GWP) fluorinated gases, the fastest growing sector of greenhouse gas (GHG) emissions globally. Baseline 2008 F-gas emissions estimates for selected chlorofluorocarbons (CFC-12), hydrochlorofluorocarbons (HCFC-22), and hydrofluorocarbons (HFC-134a) made with an inventory-based methodology were compared to emissions estimates made by ambient-based measurements. Significant discrepancies were found, with the inventory-based emissions methodology resulting in a systematic 42% under-estimation of CFC-12 emissions from older refrigeration equipment and older vehicles, and a systematic 114% overestimation of emissions for HFC-134a, a refrigerant substitute for phased-out CFCs. Initial, inventory-based estimates for all F-gas emissions had assumed that equipment is no longer in service once it reaches its average lifetime of use. Revised emission estimates using improved models for equipment age at end-of-life, inventories, and leak rates specific to California resulted in F-gas emissions estimates in closer agreement to ambient-based measurements. The discrepancies between inventory-based estimates and ambient-based measurements were reduced from -42% to -6% for CFC-12, and from +114% to +9% for HFC-134a.

  12. Ambient noise H/V spectral ratio in site effects estimation in Fateh jang area, Pakistan

    Institute of Scientific and Technical Information of China (English)

    S.M.Talha Qadri; Bushra Nawaz; S.H.Sajjad; Riaz Ahmad Sheikh

    2015-01-01

    Local geology or local site effect is a crucial component while conducting seismic risk assessment studies.Investigations made by utilization of ambient noise are an effective tool for local site estimation.The present study is conducted to perform site response analysis at 13 different sites within urban settlements of Fateh jang area (Pakistan).The aim of this study was achieved by utilizing Nakamura method or H/V spectral ratio method.Some important local site parameters,e.g.,the fundamental frequencies f0 of soft sediments,amplitudes A0 of corresponding H/V spectral ratios,and alluvium thicknesses over 13 sites within the study area,were measured and analyzed.The results show that the study area reflects low fundamental frequency f0.The fundamental frequencies of the sediments are highly variable and lie in a range of 0.6-13.0 Hz.Similarly,amplification factors at these sites are in the range of 2.0-4.0.

  13. Estimating Personal Exposures from Ambient Air Pollution Measures - Using Meta-Analysis to Assess Measurement Error

    Science.gov (United States)

    Although ambient concentrations of particulate matter ≤ 10μm (PM10) are often used as proxies for total personal exposure, correlation (r) between ambient and personal PM10 concentrations varies. Factors underlying this variation and its effect on he...

  14. Primary and secondary relaxations in supercooled eugenol and isoeugenol at ambient and elevated pressures: Dependence on chemical microstructure

    Science.gov (United States)

    Kaminska, E.; Kaminski, K.; Paluch, M.; Ngai, K. L.

    2006-04-01

    Dielectric loss spectra of two glass-forming isomers, eugenol and isoeugenol, measured at ambient and elevated pressures in the normal liquid, supercooled, and glassy states are presented. The isomeric chemical compounds studied differ only by the location of the double bond in the alkyl chain. Above the glass transition temperature Tg, the dielectric loss spectra of both isomers exhibit an excess wing on the high frequency flank of the loss peak of the α relaxation and an additional faster γ process at the megahertz frequency range. By decreasing temperature below Tg at ambient pressure or by elevating pressure above Pg, the glass transition pressure, at constant temperature, the excess wing of isoeugenol shifts to lower frequencies and is transformed into a secondary β-loss peak, while in eugenol it becomes a shoulder. These spectral features enable the β-relaxation time τβ to be determined in the glassy state. These changes indicate that the excess wings in isoeugenol and eugenol are similar and both are secondary β relaxations that are not resolved in the liquid state. While in both isoeugenol and eugenol the loss peak of the β relaxation in the glassy state and the corresponding excess wing in the liquid state shifts to lower frequencies on elevating pressure, the locations of their γ relaxation show little change with increasing pressure. The different pressure sensitivities of the excess wing and γ relaxation are further demonstrated by the nearly perfect superposition of the α-loss peak together with excess wing from the data taken at ambient pressure and at elevated pressure (and higher temperature so as to have the same α-peak frequency), but not the γ-loss peak in both isoeugenol and eugenol. On physical aging isoeugenol, the β-loss peak shifts to lower frequencies, but not the γ relaxation. Basing on these experimental facts, the faster γ relaxation is a local intramolecular process involving a side group and the slower β relaxation

  15. Radiation of X-rays using polarized LiNbO3 single crystal in low-pressure ambient gas.

    Science.gov (United States)

    Fukao, Shinji; Nakanishi, Yoshikazu; Mizoguchi, Tadahiro; Ito, Yoshiaki; Yoshikado, Shinzo

    2009-09-01

    The dependence of X-ray intensity on the pressure and type of ambient gas was investigated for LiNbO(3) single crystals polarized in the c-axis direction at pressures of approximately 1 to 30 Pa. Ionization of surrounding gas molecules by the electric field generated by the crystal led to the production of both positive ions and free electrons. The electrons were accelerated toward a Cu target, radiating both white X-rays and X-rays specific to the crystal or target material by bremsstrahlung. The integrated X-ray intensity per cycle in the energy range 1 to 20 keV showed a local maximum value at a pressure P(max). The logarithm of P(max) was proportional to the Boltzmann factor using the first ionization energy of each ambient gas molecule. The value of P(max) was found to be independent of the electrical surface area of the crystal. The integrated X-ray intensity was approximated qualitatively by a quadratic function with pressure, which was upwardly convex. It was found that one of the causes of the reduction in X-ray intensity at pressures P > P(max) is the adsorption of positive ions generated by the ionization of gas molecules on the negative electric surface. It was also discovered that the lifetime of the X-ray radiation device could be improved when the X-ray radiation case was covered with another hermetically sealed decompression case. The gas with the smallest first ionization energy, with a partial pressure of P(max), was enclosed inside the X-ray radiation case (inner case) and the gas with the largest first ionization energy was enclosed at a suitable pressure between the inner and outer cases.

  16. Thermal expansion of kyanite at ambient pressure: An X-ray powder diffraction study up to 1000 ℃

    Institute of Scientific and Technical Information of China (English)

    Xi Liu; Qiang He; Hejing Wang; Michael E. Fleet; Xiaomin Hu

    2010-01-01

    The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients: aa = 5.8(3) × 10-5, ab = 5.8 (1) × 10-5, ac% = 5.2(1) × 10-5, and av = 7.4(1) × 10-3 ℃-1, in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles a, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively.

  17. Stream ambient noise, spectrum and propagation of sounds in the goby Padogobius martensii: sound pressure and particle velocity.

    Science.gov (United States)

    Lugli, Marco; Fine, Michael L

    2007-11-01

    The most sensitive hearing and peak frequencies of courtship calls of the stream goby, Padogobius martensii, fall within a quiet window at around 100 Hz in the ambient noise spectrum. Acoustic pressure was previously measured although Padogobius likely responds to particle motion. In this study a combination pressure (p) and particle velocity (u) detector was utilized to describe ambient noise of the habitat, the characteristics of the goby's sounds and their attenuation with distance. The ambient noise (AN) spectrum is generally similar for p and u (including the quiet window at noisy locations), although the energy distribution of u spectrum is shifted up by 50-100 Hz. The energy distribution of the goby's sounds is similar for p and u spectra of the Tonal sound, whereas the pulse-train sound exhibits larger p-u differences. Transmission loss was high for sound p and u: energy decays 6-10 dB10 cm, and sound pu ratio does not change with distance from the source in the nearfield. The measurement of particle velocity of stream AN and P. martensii sounds indicates that this species is well adapted to communicate acoustically in a complex noisy shallow-water environment.

  18. Activity, sleep and ambient light have a different impact on circadian blood pressure, heart rate and body temperature rhythms.

    Science.gov (United States)

    Gubin, D G; Weinert, D; Rybina, S V; Danilova, L A; Solovieva, S V; Durov, A M; Prokopiev, N Y; Ushakov, P A

    2017-02-16

    The aim of the present study was to investigate the impact of endogenous and exogenous factors for the expression of the daily rhythms of body temperature (BT), blood pressure (BP) and heart rate (HR). One hundred and seventy-three young adults (YA), 17-24 years old (y.o.), of both genders were studied under a modified constant-routine (CR) protocol for 26 h. Participants were assigned randomly to groups with different lighting regimens: CR-LD, n = 77, lights (>400 l×) on from 09:00 to 17:00 h and off (400 l×) during the whole experimental session; CR-DD, n = 15, constant dim light (measured every 2 h. For comparison, the results of the former studies performed under conditions of regular life with an activity period from 07:00 to 23:00 h and sleep from 23:00 till 07:00 h (Control) were reanalyzed. Seven-day Ambulatory Blood Pressure Monitoring (ABPM) records from 27 YA (16-38 y.o.) and BT self-measurement data from 70 YA (17-30 y.o.) taken on ≥ 3 successive days at 08:00, 11:00, 14:00, 17:00, 20:00, 23:00 and 03:00 were available. The obtained daily patterns were different between Control and CR-DD groups, due to effects of activity, sleep and light. The comparison of Control and CR-LD groups allowed the effects of sleep and activity to be estimated since the lighting conditions were similar. The activity level substantially elevated SBP, but not DBP. Sleep, on the other hand, lowered the nighttime DBP, but has no effect on SBP. HR was affected both by activity and sleep. In accordance with previous studies, these results confirm that the steep BP increase in the morning is not driven by the circadian clock, but rather by sympathoadrenal factors related to awakening and corresponding anticipatory mechanisms. The effect on BT was not significant. To investigate the impact of light during the former dark time and darkness during the former light time, the CR-LL and CR-DD groups were each compared with the CR-LD group. Light delayed the evening decrease of BT

  19. Automatic estimation of pressure-dependent rate coefficients

    KAUST Repository

    Allen, Joshua W.

    2012-01-01

    A general framework is presented for accurately and efficiently estimating the phenomenological pressure-dependent rate coefficients for reaction networks of arbitrary size and complexity using only high-pressure-limit information. Two aspects of this framework are discussed in detail. First, two methods of estimating the density of states of the species in the network are presented, including a new method based on characteristic functional group frequencies. Second, three methods of simplifying the full master equation model of the network to a single set of phenomenological rates are discussed, including a new method based on the reservoir state and pseudo-steady state approximations. Both sets of methods are evaluated in the context of the chemically-activated reaction of acetyl with oxygen. All three simplifications of the master equation are usually accurate, but each fails in certain situations, which are discussed. The new methods usually provide good accuracy at a computational cost appropriate for automated reaction mechanism generation. This journal is © the Owner Societies.

  20. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    Directory of Open Access Journals (Sweden)

    Jagdish Narayan

    2016-02-01

    Full Text Available We report a direct conversion of hexagonal boron nitride (h-BN into pure cubic boron nitride (c-BN by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN. The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  1. Preparation of TiO sub 2 nanoparticles by pulsed laser ablation: Ambient pressure dependence of crystallization

    CERN Document Server

    Matsubara, M; Yamaki, T; Itoh, H; Abe, H

    2003-01-01

    Pulsed laser ablation (PLA) with a KrF excimer laser was used to prepare fine particles of titanium dioxide (TiO sub 2). The ablation in an atmosphere of Ar and O sub 2 (5:5) at total pressures of >= 1 Torr led to the formation of TiO sub 2 nanoparticles composed of anatase and rutile structures without any suboxides. The weight fraction of the rutile/anatase crystalline phases was dependent on the pressure of the Ar/O sub 2 gas. The TiO sub 2 nanoparticles had a spherical shape and their size, ranging from 10 and 14 nm, also appeared to be dependent on the ambient pressure. (author)

  2. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Jagdish, E-mail: narayan@ncsu.edu; Bhaumik, Anagh [Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)

    2016-02-01

    We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  3. Structure, Mobility, and Composition of Transition Metal Catalyst Surfaces. High-Pressure Scanning Tunneling Microscopy and Ambient-Pressure X-ray Photoelectron Spectroscopy Studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhongwei [Univ. of California, Berkeley, CA (United States)

    2013-12-06

    Surface structure, mobility, and composition of transition metal catalysts were studied by high-pressure scanning tunneling microscopy (HP-STM) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at high gas pressures. HP-STM makes it possible to determine the atomic or molecular rearrangement at catalyst surfaces, particularly at the low-coordinated active surface sites. AP-XPS monitors changes in elemental composition and chemical states of catalysts in response to variations in gas environments. Stepped Pt and Cu single crystals, the hexagonally reconstructed Pt(100) single crystal, and Pt-based bimetallic nanoparticles with controlled size, shape and composition, were employed as the model catalysts for experiments in this thesis.

  4. Cause-specific premature death from ambient PM2.5 exposure in India: Estimate adjusted for baseline mortality.

    Science.gov (United States)

    Chowdhury, Sourangsu; Dey, Sagnik

    2016-05-01

    In India, more than a billion population is at risk of exposure to ambient fine particulate matter (PM2.5) concentration exceeding World Health Organization air quality guideline, posing a serious threat to health. Cause-specific premature death from ambient PM2.5 exposure is poorly known for India. Here we develop a non-linear power law (NLP) function to estimate the relative risk associated with ambient PM2.5 exposure using satellite-based PM2.5 concentration (2001-2010) that is bias-corrected against coincident direct measurements. We show that estimate of annual premature death in India is lower by 14.7% (19.2%) using NLP (integrated exposure risk function, IER) for assumption of uniform baseline mortality across India (as considered in the global burden of disease study) relative to the estimate obtained by adjusting for state-specific baseline mortality using GDP as a proxy. 486,100 (811,000) annual premature death in India is estimated using NLP (IER) risk functions after baseline mortality adjustment. 54.5% of premature death estimated using NLP risk function is attributed to chronic obstructive pulmonary disease (COPD), 24.0% to ischemic heart disease (IHD), 18.5% to stroke and the remaining 3.0% to lung cancer (LC). 44,900 (5900-173,300) less premature death is expected annually, if India achieves its present annual air quality target of 40μgm(-3). Our results identify the worst affected districts in terms of ambient PM2.5 exposure and resulting annual premature death and call for initiation of long-term measures through a systematic framework of pollution and health data archive.

  5. Estimation of ex-vessel steam explosion pressure loads

    Energy Technology Data Exchange (ETDEWEB)

    Leskovar, Matjaz [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia)], E-mail: matjaz.leskovar@ijs.si; Ursic, Mitja [Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia)

    2009-11-15

    An ex-vessel steam explosion may occur when, during a severe reactor accident, the reactor vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles that may endanger surrounding structures. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. In this article, different scenarios of ex-vessel steam explosions in a typical pressurized water reactor cavity are analyzed with the code MC3D, which is being developed for the simulation of fuel-coolant interactions. A parametric study was performed varying the location of the melt release (central, right and left side melt pour), the cavity water subcooling, the primary system overpressure at vessel failure and the triggering time for explosion calculations. The main purpose of the study was to establish the influence of the varied parameters on the fuel-coolant interaction behaviour, to determine the most challenging cases and to estimate the expected pressure loadings on the cavity walls. For the most explosive central, right side and left side melt pour scenarios a detailed analysis of the explosion simulation results was performed. The study shows that for some ex-vessel steam explosion scenarios higher pressure loads are predicted than obtained in the OECD programme SERENA phase 1.

  6. Non-invasive estimation of blood pressure using ultrasound contrast agents

    DEFF Research Database (Denmark)

    Andersen, Klaus Scheldrup; Jensen, Jørgen Arendt

    2009-01-01

    Local blood pressure measurements provide important information on the state of health of organs in the body and can be used to diagnose diseases in the heart, lungs, and kidneys. This paper presents an experimental setup for investigating the ambient pressure sensitivity of a contrast agent using...

  7. Characterization Testing of H20-SO2 Electrolyzer at Ambient Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Steimke, J

    2005-07-29

    are included to allow variation of the operating pressure in the range of 1 to 2 bar. Hydrogen generated at the cathode of the cell can be collected for the purpose of flow measurement and composition analysis. The test facility proved to be easy to operate, versatile, and reliable. Two slightly different SDE's were designed, procured and tested. The first electrolyzer was based on a commercially available PEM water electrolyzer manufactured by Proton Energy Systems, Inc. (PES). The PES electrolyzer was built with Hastelloy B and Teflon wetted parts, a PEM electrolyte, and porous titanium electrodes. The second electrolyzer was assembled for SRNL by the University of South Carolina (USC). It was constructed with platinized carbon cloth electrodes, a Nafion 115 PEM electrolyte, carbon paper flow fields, and solid graphite back plates. Proof-of-concept testing was performed on each electrolyzer at near-ambient pressure and room temperature under various feed conditions. SDE operation was evidenced by hydrogen production at the cathode and sulfuric acid production at the anode (witnessed by the absence of oxygen generation) and with cell voltages substantially less than the theoretical reversible voltage for simple water electrolysis (1.23 V). Cell performance at low currents equaled or exceeded that achieved in the two-compartment cells built by Westinghouse Electric Corporation during the original development of the HyS Process. Performance at higher currents was less efficient due to mass transfer and hydraulic issues associated with the use of cells not optimized for liquid feed. Test results were analyzed to determine performance trends, improvement needs, and long-term SDE potential. The PES cell failed after several days of operation due to internal corrosion of the titanium electrodes in the presence of sulfuric acid. Although it was anticipated that the titanium would react in the presence of acid, the rapid deterioration of the electrodes was unexpected

  8. Ionization mechanism of the ambient pressure pyroelectric ion source (APPIS) and its applications to chemical nerve agent detection.

    Science.gov (United States)

    Neidholdt, Evan L; Beauchamp, J L

    2009-11-01

    We present studies of the ionization mechanism operative in the ambient pressure pyroelectric ionization source (APPIS), along with applications that include detection of simulants for chemical nerve agents. It is found that ionization by APPIS occurs in the gas-phase. As the crystal is thermally cycled over a narrow temperature range, electrical discharges near the surface of the crystal produce energetic species which, through reactions with atmospheric molecules, result in reactant ions such as protonated water clusters or clusters of hydroxide and water. Reactant ions can be observed directly in the mass spectrometer. These go on to react with trace neutrals via proton transfer reactions to produce the ions observed in mass spectra, which are usually singly protonated or deprotonated species. Further implicating gas-phase ionization, observed product distributions are highly dependent on the composition of ambient gases, especially the concentration of water vapor and oxygen surrounding the source. For example, basic species such as triethylamine are observed as singly protonated cations at a water partial pressure of 10 torr. At a water pressure of 4 torr, reactive oxygen species are formed and lead to observation of protonated amine oxides. The ability of the APPIS source to detect basic molecules with high proton affinities makes it highly suited for the detection of chemical nerve agents. We demonstrate this application using simulants corresponding to VX and GA (Tabun). With the present source configuration pyridine is detected readily at a concentration of 4 ppm, indicating ultimate sensitivity in the high ppb range.

  9. A Combined State of Charge Estimation Method for Lithium-Ion Batteries Used in a Wide Ambient Temperature Range

    Directory of Open Access Journals (Sweden)

    Fei Feng

    2014-05-01

    Full Text Available Ambient temperature is a significant factor that influences the characteristics of lithium-ion batteries, which can produce adverse effects on state of charge (SOC estimation. In this paper, an integrated SOC algorithm that combines an advanced ampere-hour counting (Adv Ah method and multistate open-circuit voltage (multi OCV method, denoted as “Adv Ah + multi OCV”, is proposed. Ah counting is a simple and general method for estimating SOC. However, the available capacity and coulombic efficiency in this method are influenced by the operating states of batteries, such as temperature and current, thereby causing SOC estimation errors. To address this problem, an enhanced Ah counting method that can alter the available capacity and coulombic efficiency according to temperature is proposed during the SOC calculation. Moreover, the battery SOCs between different temperatures can be mutually converted in accordance with the capacity loss. To compensate for the accumulating errors in Ah counting caused by the low precision of current sensors and lack of accurate initial SOC, the OCV method is used for calibration and as a complement. Given the variation of available capacities at different temperatures, rated/non-rated OCV–SOCs are established to estimate the initial SOCs in accordance with the Ah counting SOCs. Two dynamic tests, namely, constant- and alternated-temperature tests, are employed to verify the combined method at different temperatures. The results indicate that our method can provide effective and accurate SOC estimation at different ambient temperatures.

  10. Spectroscopic studies of surface-gas interactions and catalyst restructuring at ambient pressure: mind the gap{exclamation_point}

    Energy Technology Data Exchange (ETDEWEB)

    Rupprechter, Guenther; Weilach, Christian [Institute of Materials Chemistry, Vienna University of Technology, Veterinaerplatz 1, A-1210 Vienna (Austria)], E-mail: grupp@imc.tuwien.ac.at

    2008-05-07

    Recent progress in the application of surface vibrational spectroscopy at ambient pressure allows us to monitor surface-gas interactions and heterogeneous catalytic reactions under conditions approaching those of technical catalysis. The surface specificity of photon-based methods such as polarization modulation infrared reflection absorption spectroscopy (PM-IRAS) and sum frequency generation (SFG) spectroscopy is utilized to monitor catalytically active surfaces while they function at high pressure and high temperature. Together with complementary information from high-pressure x-ray photoelectron spectroscopy (HP-XPS) and high-resolution transmission electron microscopy (HRTEM), reaction mechanisms can be deduced on a molecular level. Well defined model catalysts, prepared under ultrahigh vacuum (UHV), are typically employed in such studies, including smooth and stepped single crystals, thin oxide films, and oxide-supported nanoparticles. A number of studies on unsupported and supported noble metal (Pd, Rh) catalysts are presented, focusing on the transformation of the catalysts from the 'as-prepared' to the 'active state'. This often involves pronounced alterations in catalyst structure and composition, for example the creation of surface carbon phases, surface oxides or surface alloys, as well as nanoparticle restructuring. The reactivity studies include CH{sub 3}OH, CH{sub 4} and CO oxidation with gas phase analysis by gas chromatography and mass spectrometry. Differing results between studies under ultrahigh vacuum and ambient pressure, and between studies on single crystals and supported nanoparticles, demonstrate the importance of 'minding the gap' between idealized and realistic conditions.

  11. Two-phase flows and heat transfer within systems with ambient pressure above the thermodynamic critical pressure

    Science.gov (United States)

    Hendricks, R. C.; Braun, M. J.; Mullen, R. L.

    1986-01-01

    In systems where the design inlet and outlet pressure P sub amb are maintained above the thermodynamic critical pressure P sub c, it is often assumed that heat and mass transfer are governed by single-phase relations and that two-phase flows cannot occur. This simple rule of thumb is adequate in many low-power designs but is inadequate for high-performance turbomachines, boilers, and other systems where two-phase regions can exist even though P sub amb P sub c. Heat and mass transfer and rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two-phase zone can differ significantly from those for a single-phase zone. By using a laminar, variable-property bearing code and a rotating boiler code, pressure and temperature surfaces were determined that illustrate nesting of a two-phase region within a supercritical pressure region. The method of corresponding states is applied to bearings with reasonable rapport.

  12. Effect of various structure directing agents on the physicochemical properties of the silica aerogels prepared at an ambient pressure

    KAUST Repository

    Sarawade, Pradip

    2013-12-01

    We studied the effects of various surfactants on the textural properties (BET surface area, pore size, and pore volume) of the silica aerogels prepared at an ambient pressure. A simple surface modification of silica gel prepared at an ambient pressure through hydrolysis and polycondensation of TEOS as asilica precursor was conducted using various structure directing agents. The treatment was found to induce a significant difference in the porosity of the silica aerogel. Highly porous silica aerogels with bimodal porous structures were prepared by modifying the surface of the silica wet-gel (alcogel) with trimethylchlorosilane (TMCS) in order to preserve its porosity. The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. In this work, a possible new type of highly porous hydrophobic silica aerogel with a bimodal porous structure is presented. A hydrophilic extremely porous (high surface area and large pore volume) silica aerogel was obtained by heating the as-synthesized hydrophobic silica aerogel at 400°C for 1 h. There was a significant effect of structure directing agent on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the silicaaerogels. © 2013 Elsevier B.V. All rights reserved.

  13. Characterization of direct-current atmospheric-pressure discharges useful for ambient desorption/ionization mass spectrometry.

    Science.gov (United States)

    Shelley, Jacob T; Wiley, Joshua S; Chan, George C Y; Schilling, Gregory D; Ray, Steven J; Hieftje, Gary M

    2009-05-01

    Two relatively new ambient ionization sources, direct analysis in real time (DART) and the flowing atmospheric-pressure afterglow (FAPA), use direct current, atmospheric-pressure discharges to produce reagent ions for the direct ionization of a sample. Although at a first glance these two sources appear similar, a fundamental study reveals otherwise. Specifically, DART was found to operate with a corona-to-glow transition (C-G) discharge whereas the FAPA was found to operate with a glow-to-arc transition (G-A) discharge. The characteristics of both discharges were evaluated on the basis of four factors: reagent-ion production, response to a model analyte (ferrocene), infrared (IR) thermography of the gas used for desorption and ionization, and spatial emission characteristics. The G-A discharge produced a greater abundance and a wider variety of reagent ions than the C-G discharge. In addition, the discharges yielded different adducts and signal strengths for ferrocene. It was also found that the gas exiting the discharge chamber reached a maximum of 235 degrees C and 55 degrees C for the G-A and C-G discharges, respectively. Finally, spatially resolved emission maps of both discharges showed clear differences for N(2)(+) and O(I). These findings demonstrate that the discharges used by FAPA and DART are fundamentally different and should have different optimal applications for ambient desorption/ionization mass spectrometry (ADI-MS).

  14. Surface desorption atmospheric pressure chemical ionization mass spectrometry for direct ambient sample analysis without toxic chemical contamination.

    Science.gov (United States)

    Chen, Huanwen; Zheng, Jian; Zhang, Xie; Luo, Mingbiao; Wang, Zhichang; Qiao, Xiaolin

    2007-08-01

    Ambient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is used as a reagent to generate primary ions such as H(3)O(+), which is then directed to impact the sample surface for desorption and ionization. Under experimental conditions, protonated or deprotonated molecules of analytes present on various samples are observed using positive or negative corona discharge. Fast detection of trace amounts of analytes present in pharmaceutical preparations, viz foods, skins and clothes has been demonstrated without any sample pretreatment. Taking the advantage of the gasless setup, powder samples such as amino acids and mixtures of pharmaceutical preparations are rapidly analyzed. Impurities such as sudan dyes in tomato sauce are detected semiquantitatively. Molecular markers (e.g. putrescine) for meat spoilage are successfully identified from an artificially spoiled fish sample. Chemical warfare agent stimulants, explosives and herbicides are directly detected from the skin samples and clothing exposed to these compounds. This provides a detection limit of sub-pg (S/N > or = 3) range in MS2. Metabolites and consumed chemicals such as glucose are detected successfully from human skins. Conclusively, surface desorption atmospheric pressure chemical ionization (DAPCI) mass spectrometry, without toxic chemical contamination, detects various compounds in complex matrices, showing promising applications for analyses of human related samples.

  15. Estimation of Eastern Denmark’s Electromechanical Modes from Ambient Phasor Measurement Data

    DEFF Research Database (Denmark)

    Vanfretti, Luigi; Garcia-Valle, Rodrigo; Uhlen, Kjetil;

    2010-01-01

    on the Danish power grid and its interconnections, and describe the features of an experimental phasor measurement unit designed by DTU which is used to provide the measurements used in this investigation. Parametric and non-parametric block processing techniques are applied to 48 hours of ambient data recorded...

  16. Application of Ambient Analysis Techniques for the Estimation of Electromechanical Oscillations from Measured PMU Data in Four Different Power Systems

    DEFF Research Database (Denmark)

    Vanfretti, Luigi; Dosiek, Luke; Pierre, John W.

    2011-01-01

    The application of advanced signal processing techniques to power system measurement data for the estimation of dynamic properties has been a research subject for over two decades. Several techniques have been applied to transient (or ringdown) data, ambient data, and to probing data. Some...... of these methodologies have been included in off-line analysis software, and are now being incorporated into software tools used in control rooms for monitoring the near real-time behavior of power system dynamics. In this paper we illustrate the practical application of some ambient analysis methods......-synchronized Frequency Disturbance Recorder (FDR) data from Nigeria. It is shown that available signal processing tools are readily applicable for analysis of different power systems, regardless of their specific dynamic characteristics. The discussions and results in this paper are of value to power system operators...

  17. Noninvasive Subharmonic Pressure Estimation for Monitoring Breast Cancer Response to Neoadjuvant Therapy

    Science.gov (United States)

    2013-01-01

    AD_________________ Award Number: W81XWH-08-1-0503 TITLE: Noninvasive Subharmonic Pressure...SUBTITLE 5a. CONTRACT NUMBER Noninvasive Subharmonic Pressure Estimation for Monitoring Breast Cancer Response to Neoadjuvant Therapy 5b. GRANT...SUBTITLE Noninvasive Subharmonic Pressure Estimation for Monitoring Breast Cancer 5. FUNDING NUMBERS W81XWH-08-1-0503 6. AUTHOR(S) Flemming

  18. Real-Time Personalized Monitoring to Estimate Occupational Heat Stress in Ambient Assisted Working

    OpenAIRE

    Pablo Pancardo; Acosta, Francisco D.; José Adán Hernández-Nolasco; Miguel A. Wister; Diego López-de-Ipiña

    2015-01-01

    Ambient Assisted Working (AAW) is a discipline aiming to provide comfort and safety in the workplace through customization and technology. Workers’ comfort may be compromised in many labor situations, including those depending on environmental conditions, like extremely hot weather conduces to heat stress. Occupational heat stress (OHS) happens when a worker is in an uninterrupted physical activity and in a hot environment. OHS can produce strain on the body, which leads to discomfort and eve...

  19. An affordable cuff-less blood pressure estimation solution.

    Science.gov (United States)

    Jain, Monika; Kumar, Niranjan; Deb, Sujay

    2016-08-01

    This paper presents a cuff-less hypertension pre-screening device that non-invasively monitors the Blood Pressure (BP) and Heart Rate (HR) continuously. The proposed device simultaneously records two clinically significant and highly correlated biomedical signals, viz., Electrocardiogram (ECG) and Photoplethysmogram (PPG). The device provides a common data acquisition platform that can interface with PC/laptop, Smart phone/tablet and Raspberry-pi etc. The hardware stores and processes the recorded ECG and PPG in order to extract the real-time BP and HR using kernel regression approach. The BP and HR estimation error is measured in terms of normalized mean square error, Error Standard Deviation (ESD) and Mean Absolute Error (MAE), with respect to a clinically proven digital BP monitor (OMRON HBP1300). The computed error falls under the maximum standard allowable error mentioned by Association for the Advancement of Medical Instrumentation; MAE <; 5 mmHg and ESD <; 8mmHg. The results are validated using two-tailed dependent sample t-test also. The proposed device is a portable low-cost home and clinic bases solution for continuous health monitoring.

  20. Estimation of lung volume and pressure from electrocardiogram

    KAUST Repository

    Elsayed, Gamal Eldin Fathy Amin

    2011-05-01

    The Electrocardiography (ECG) is a tool measuring the electrical excitation of the heart that is extensively used for diagnosis and monitoring of heart diseases. The ECG signal reflects not only the heart activity but also many other physiological processes. The respiratory activity is a prominent process that affects the ECG signal due to the close proximity of the heart and the lungs and, on the other hand, due to neural regulatory processes. In this paper, several means for the estimation of the respiratory process from the ECG signal are presented. The results show a strong correlation of the voltage difference between the R and S peak of the ECG and the lung\\'s volume and pressure. Correlation was also found for some features of the vector ECG, which is a two dimensional graph of two different ECG signals. The potential benefit of the multiparametric evaluation of the ECG signal is a reduction of the number of sensors connected to patients, which will increase the patients\\' comfort and reduce the costs associated with healthcare. In particular, it is relevant for sleep monitoring, where a reduction of the number of different sensors would facilitate a more natural sleeping environment and hence a higher sensitivity of the diagnosis. © 2011 IEEE.

  1. Noninvasive Subharmonic Pressure Estimation for Monitoring Breast Cancer Response to Neoadjuvant Threapy

    Science.gov (United States)

    2009-09-01

    TITLE AND SUBTITLE Noninvasive Subharmonic Pressure Estimation for Monitoring Breast Cancer 5. FUNDING NUMBERS W81XWH-08-1-0503 6. AUTHOR(S...u sing subharmonic aided p ressure estimation (SHAPE ) to estimate the inte rstitial fluid pressure (IFP) in LABC. To date, in vitr o experiments

  2. Surface Pressure Estimates for Pitching Aircraft Model at High Angles-of-attack (Short Communication)

    OpenAIRE

    A.A. Pashilkar

    2002-01-01

    The surface pressure on a pitching delta wing aircraft is estimated from the normal force and the pitching moment characteristics. The pressure model is based on parametrising the surface pressure distribution on a simple delta wing. This model is useful as a first approximation of the load distribution on the aircraft wing. Leeward surface pressure distributions computed by this method are presented.

  3. Casein Micelles at Non-Ambient Pressure Studied by Neutron Scattering

    NARCIS (Netherlands)

    Tromp, Hans; Huppertz, Thom; Kohlbrecher, Joachim

    2015-01-01

    The disruption of caseinmicelles, as found in cows’ milk, was investigated at pressures up to 300 MPa with small angle neutron scattering (SANS). From the decrease of the overall level of scattering, the expected disruption of the micelles was concluded. This disruption was incomplete, and stable at

  4. Characterization of Ultrafast Laser-Ablation Plasma Plumes at Various Ar Ambient Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Diwakar, P. K.; Harilal, S. S.; Phillips, Mark C.; Hassanein, A.

    2015-07-28

    Expansion dynamics and internal plume structures of fs laser ablated brass plasma in Ar at various pressure levels ranging from vacuum to atmospheric were studied using multitude of diagnostic tools including time resolved and time integrated 2-dimensional imaging, optical time of flight measurements and visible emission spectroscopy. Temporal evolution of excited Cu and Zn species in the plume were imaged using band pass interference filters and compared its hydrodynamic expansion features with spectrally integrated images of the plume. 2D imaging coupled with monochromatic line selection showed several interesting features at various pressure levels which include velocity differences among the plume species, emission intensity distribution, plasma temperature, electron density etc. Plume confinement, enhanced signal intensity, and dual peak structures in time-of-flight profiles were observed at intermediate pressure range of ~10 Torr. Optimum signal to background ratio was also observed in this pressure range. Possible mechanisms for observed changes in plume shape, optical emission intensity and dual peak structures in time-of-flight profiles were discussed.

  5. Observation of in situ oxidation dynamics of vanadium thin film with ambient pressure X-ray photoemission spectroscopy

    Science.gov (United States)

    Kim, Geonhwa; Yoon, Joonseok; Yang, Hyukjun; Lim, Hojoon; Lee, Hyungcheol; Jeong, Changkil; Yun, Hyungjoong; Jeong, Beomgyun; Crumlin, Ethan; Lee, Jouhahn; Lee, Jaeyoung; Ju, Honglyoul; Mun, Bongjin Simon

    2016-11-01

    The evolution of oxidation/reduction states of vanadium oxide thin film was monitored in situ as a function of oxygen pressure and temperature via ambient pressure X-ray photoemission spectroscopy. Spectra analysis showed that VO2 can be grown at a relatively low temperature, T ˜ 523 K, and that V2O5 oxide develops rapidly at elevated oxygen pressure. Raman spectroscopy was applied to confirm the formation of VO2 oxide inside of the film. In addition, the temperature-dependent resistivity measurement on the grown thin film, e.g., 20 nm exhibited a desirable metal-insulator transition of VO2 with a resistivity change of ˜1.5 × 103 times at 349.3 K, displaying typical characteristics of thick VO2 film, e.g., 100 nm thick. Our results not only provide important spectroscopic information for the fabrication of vanadium oxides, but also show that high quality VO2 films can be formed at relatively low temperature, which is highly critical for engineering oxide film for heat-sensitive electronic devices.

  6. The effects of added hydrogen on a helium atmospheric-pressure plasma jet ambient desorption/ionization source.

    Science.gov (United States)

    Wright, Jonathan P; Heywood, Matthew S; Thurston, Glen K; Farnsworth, Paul B

    2013-03-01

    We present mass spectrometric data demonstrating the effect that hydrogen has on a helium-based dielectric-barrier discharge (DBD) atmospheric-pressure plasma jet used as an ambient desorption/ionization (ADI) source. The addition of 0.9 % hydrogen to the helium support gas in a 35-W plasma jet increased signals for a range of test analytes, with enhancement factors of up to 68, without proportional increases in background levels. The changes in signal levels result from a combination of changes in the desorption kinetics from the surface and increased ion production in the gas phase. The enhancement in ADI-MS performance despite the quenching of key plasma species reported in earlier studies suggests that ionization with a H2/He plasma jet is the result of an alternate mechanism involving the direct generation of ionized hydrogen.

  7. Salt Survey Comparison of Pressurized vs Ambient Deck Air Intakes on JEFF (B) Hovercraft

    Science.gov (United States)

    1981-02-02

    10 Vegetation Collected on Lift Fan Screen 21 Figure 11 Paint Stripping in Lift Fan Shows Dirty vs Clean Air 22 APPENDIX FIGURES Figure A-l Nuclepore...terms of the readings on deck and that ingested in No. 6 engine. Although one single reading is insufficient to draw any fir * conclusions, these data, on...salt above 0.14 PPM, correlates with AVCO experimental data (TF-35 engine). 11. The pressurized engine data demonstrated that the effectof leakage

  8. Dry Kraft Pulping at Ambient Pressure for Cost Effective Energy Saving and Pollution Deduction

    Energy Technology Data Exchange (ETDEWEB)

    Yulin Deng; Art Ragauskas

    2012-08-28

    Sponsored by the DOE Industrial Energy Efficiency Grand Challenge program, our research team at the Georgia Institute of Technology conducted laboratory studies and confirmed the concept of making wood pulp using a dry pulping technology. This technology is a new process different from any prior pulping technology used in Kraft and CTMP pulping. Three different kinds of dry pulping methods were investigated. (a) Dry Pulping at Atmospheric Pressure: The first one is to dry and bake the pretreated woodchips in a conventional oven at atmospheric pressure without the use of a catalyst. (b) Dry Pulping at Reduced Pressure: The second method is to dry the pretreated woodchips first in a vacuum oven in the presence of anthraquinone (AQ) as a pulping catalyst, followed by baking at elevated temperature. (c) Liquid Free Chemical Pulping, LFCP. The third method is to first remove the free water of pretreated woodchips, followed by dry pulping using a conventional Kraft pulping digester with AQ and triton as additives. Method one: Experimental results indicated that Dry Pulping at Atmospheric Pressure could produce pulp with higher brightness and lower bulk than conventional Kraft pulp. However, tensile strength of the acquired pulp is much lower than traditional Kraft pulp, and their Kappa number and energy consumption are higher than conventional Kraft pulp. By fully analyzing the results, we concluded that wood fibers might be damaged during the drying process at elevated temperature. The main reason for wood fiber damage is that a long drying time was used during evaporation of water from the woodchips. This resulted in an un-uniform reaction condition on the woodchips: the outside layer of the woodchips was over reacted while inside the woodchips did not reacted at all. To solve this problem, dry pulping at reduced pressure was investigated. Method two: To achieve uniform reaction throughout the entire reaction system, the water inside the pretreated woodchips was

  9. Impacts of Ambient Temperature and Pressure on PM2.5 Emission Profiles of Light-Duty Diesel Vehicles

    Science.gov (United States)

    Wang, Chenyu; Wu, Ye; Li, Zhenhua; Hao, Jiming

    2012-01-01

    The impact of the environmental factors on the emissions of particulate matter (PM) number, size distribution and mass size distribution from diesel passenger cars was evaluated. Particle measurements from five modern light-duty diesel vehicles (LDDV) were performed in June and November 2011. Commercial low sulfur diesel fuel (less than 50 ppm) was used during the testing of these vehicles which were not equipped with after-treatment devices. The dynamometer test was based on the Economic Commission of Europe (ECE) 15 cycles. The results indicate that PM2.5 emissions from LDDV are significantly affected by ambient temperature and pressure. A comparison of the emissions concentration of PM2.5 in these two different months showed that the number concentration in June was (3.8 ± 0.69) × 107 cm-3 and (2.5 ± 0.66) × 107 cm-3 in November. The PM concentration of about 30 nm diameter was 25 ± 6% of the total emissions in November while only 14 ± 3% of total emissions in June. In the 60 nm to 2.5 μm test range, November data shows less of a contribution for number than data from June testing. The concentration of mass emissions in June was (325 ± 44) mg/m3 and (92 ± 30) mg/m3 in November. The contribution of the number of PM particles in November testing is lower than testing in June by 34% and the mass concentration in November is 70% lower than that in June. With the decrease of ambient temperature and the increase of ambient pressure, both the oxygen concentration in cylinder and air-fuel ratio are increased, which caused lower particle number and mass emissions during November testing. The size distribution is also altered by these changes: the more efficient in-cylinder combustion resulted in a higher proportion of particles in the 30 nm and smaller range than for other particle sizes.

  10. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure.

    Science.gov (United States)

    Surrey, Alexander; Schultz, Ludwig; Rellinghaus, Bernd

    2017-01-31

    The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a "nanoreactor" is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH2, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  11. Estimation of annual energy production using dynamic wake meandering in combination with ambient CFD solutions

    Science.gov (United States)

    Hahn, S.; Machefaux, E.; Hristov, Y. V.; Albano, M.; Threadgill, R.

    2016-09-01

    In the present study, combination of the standalone dynamic wake meandering (DWM) model with Reynolds-averaged Navier-Stokes (RANS) CFD solutions for ambient ABL flows is introduced, and its predictive performance for annual energy production (AEP) is evaluated against Vestas’ SCADA data for six operating wind farms over semi-complex terrains under neutral conditions. The performances of conventional linear and quadratic wake superposition techniques are also compared, together with the in-house implemention of successive hierarchical merging approaches. As compared to our standard procedure based on the Jensen model in WindPRO, the overall results are promising, leading to a significant improvement in AEP accuracy for four of the six sites. While the conventional linear superposition shows the best performance for the improved four sites, the hierarchical square superposition shows the least deteriorated result for the other two sites.

  12. 缓冲气压对CO2激光Al靶等离子体参量的影响%Analysis of the properties of CO2 laser-induced aluminum plasma at different ambient pressures

    Institute of Scientific and Technical Information of China (English)

    吴涛; 王新兵; 唐建; 饶志明; 王少义

    2011-01-01

    为了研究缓冲气压对激光等离子体参量的影响,利用CO2激光烧蚀Al靶产生等离子体,缓冲气压变化范围为10-4pa ~2×103Pa,激光脉冲能量为180mJ/脉冲,在局域热平衡和光学薄等离子体假设下,采用发射光谱法计算了等离子体的电子温度和电子密度,并研究了缓冲气压对这些参量的影响.结果表明,等离子体的电子温度和电子密度分别在1.05eV ~2.47eV与1.95×1016cm-3~10.5×1016cm-3范围内,Al等离子体的电子温度随气压的增大而减少;低缓冲气压时,电子密度随气压增大而减小,当气压达到600Pa时,激光脉冲会击穿空气形成等离子体,电子密度又开始上升,当气压超过3000Pa时,空气等离子体会屏蔽激光脉冲能量,使到达靶面的激光能量急剧下降,Al原子的特征谱线也随之减弱而几乎消失.这一结果对理解缓冲气压对激光与物质相互作用过程的影响是有帮助的.%In order to study the properties of laser-induced plasma at different ambient pressures, emission spectroscopy was studied on aluminum plasma generated by C02 laser with energy of 180mJ/pulse at different air ambient pressures. The dependency of plasma temperature and density on ambient pressures were estimated from the analysis of spectral data by assuming the conditions of local thermodynamic equilibrium and optically thin plasma. Electron temperature was measured in the range of 1. 05eV ~2.47eV, and electron density was measured in the range of 1. 95 x 1016cm-3 ~ 10. 5 x 1016cm-3, as the ambient pressure was varied from 10-4Pa to 2 x 103Pa. The results show that the plasma temperature decreases with the ambient pressures. At first, the electron density decreases with the increase of ambient pressure under low pressure. When the pressure reaches 600Pa, the broken air plasma may interact with Al vapor and the electron density increases with the pressure increasing. For larger ambient pressure up to 3000Pa, the Al emission

  13. A high-temperature, ambient-pressure ultra-dry operando reactor cell for Fourier-transform infrared spectroscopy

    Science.gov (United States)

    Köck, Eva-Maria; Kogler, Michaela; Pramsoler, Reinhold; Klötzer, Bernhard; Penner, Simon

    2014-08-01

    The construction of a newly designed high-temperature, high-pressure FT-IR reaction cell for ultra-dry in situ and operando operation is reported. The reaction cell itself as well as the sample holder is fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high-temperature zone. Special emphasis was put on chemically absolute water-free and inert experimental conditions, which includes reaction cell and gas-feeding lines. Operation and spectroscopy up to 1273 K is possible, as well as pressures up to ambient conditions. The reaction cell exhibits a very easy and variable construction and can be adjusted to any available FT-IR spectrometer. Its particular strength lies in its possibility to access and study samples under very demanding experimental conditions. This includes studies at very high temperatures, e.g., for solid-oxide fuel cell research or studies where the water content of the reaction mixtures must be exactly adjusted. The latter includes all adsorption studies on oxide surfaces, where the hydroxylation degree is of paramount importance. The capability of the reaction cell will be demonstrated for two selected examples where information and in due course a correlation to other methods can only be achieved using the presented setup.

  14. Synthesis of tungsten oxide nanoparticles using a hydrothermal method at ambient pressure

    DEFF Research Database (Denmark)

    Ahmadi, Majid; Younesi, Reza; Guinel, Maxime J-F

    2014-01-01

    ) nanoparticles were synthesized using a simple and inexpensive low temperature and low pressure hydrothermal (HT) method. The precursor solution used for the HT process was prepared by adding hydrochloric acid to diluted sodium tungstate solutions (Na2WO4 center dot 2H(2)O) at temperatures below 5 degrees C...... of WO3 nanoparticles using this method is therefore a three step process: protonation of tungstate ions, crystallization of tungstite, and phase transformation to WO3. Furthermore, this process can be tailored. For example, we show that WO3 can be doped with cesium and that nanorods can also be obtained......Tungsten oxide (WO3) nanostructures receive sustained interest for a wide variety of applications, and especially for its usage as a photocatalyst. It is therefore important to find suitable methods allowing for its easy and inexpensive large scale production. Tungstite (WO3 center dot H2O...

  15. Measurement of Apparent Thermal Conductivity of JSC-1A Under Ambient Pressure

    Science.gov (United States)

    Yuan, Zeng-Guang; Kleinhenz, Julie E.

    2011-01-01

    The apparent thermal conductivity of JSC-1A lunar regolith simulant was measured experimentally using a cylindrical apparatus. Eleven thermocouples were embedded in the simulant bed to obtain the steady state temperature distribution at various radial, axial, and azimuthal locations. The high aspect ratio of a cylindrical geometry was proven to provide a one-dimensional, axisymmetric temperature field. A test series was performed at atmospheric pressure with varying heat fluxes. The radial temperature distribution in each test fit a logarithmic function, indicating a constant thermal conductivity throughout the soil bed. However, thermal conductivity was not constant between tests at different heat fluxes. This variation is attributed to stresses created by thermal expansion of the simulant particles against the rigid chamber wall. Under stress-free conditions (20 deg C), the data suggest a temperature independent apparent conductivity of 0.1961 +/- 0.0070 W/m/ deg C

  16. Non-invasive Estimation of Pressure Changes along a Streamline using Vector Velocity Ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Villagómez Hoyos, Carlos Armando; Traberg, Marie Sand;

    2015-01-01

    estimator is evaluated by comparing its results to a 3-D numerical simulation model. The study showed pressure drops across the constricted phantom varying from -5 Pa to 7 Pa with a standard deviation of 4%. The proposed method had a normalised rootmean-square error of 10% in reference to the simulation......A non-invasive method for estimating pressure changes along a streamline using ultrasound is presented. The suggested method estimates pressure gradients from 2-D vector velocity fields. Changes in pressure are derived using a model based on the Navier-Stokes equations. Scans of a carotid...

  17. Strong ferromagnetic exchange interaction under ambient pressure in BaFe2S3

    Science.gov (United States)

    Wang, Meng; Jin, S. J.; Yi, Ming; Song, Yu; Jiang, H. C.; Zhang, W. L.; Sun, H. L.; Luo, H. Q.; Christianson, A. D.; Bourret-Courchesne, E.; Lee, D. H.; Yao, Dao-Xin; Birgeneau, R. J.

    2017-02-01

    Inelastic neutron scattering measurements have been performed to investigate the spin waves of the quasi-one-dimensional antiferromagnetic ladder compound BaFe2S3 , where a superconducting transition was observed under pressure [H. Takahashi et al., Nat. Mater. 14, 1008 (2015), 10.1038/nmat4351; T. Yamauchi et al., Phys. Rev. Lett. 115, 246402 (2015), 10.1103/PhysRevLett.115.246402]. By fitting the spherically averaged experimental data collected on a powder sample to a Heisenberg Hamiltonian, we find that the one-dimensional antiferromagnetic ladder exhibits a strong nearest-neighbor ferromagnetic exchange interaction (S JR=-71 ±4 meV) along the rung direction, an antiferromagnetic S JL=49 ±3 meV along the leg direction, and a ferromagnetic S J2=-15 ±2 meV along the diagonal direction. Our data demonstrate that the antiferromagnetic spin excitations are a common characteristic for the iron-based superconductors, while specific relative values for the exchange interactions do not appear to be unique for the parent states of the superconducting materials.

  18. New ambient pressure organic superconductor with Tc = 8.1 K : (EDT-TTF)4Hg3-dI8

    NARCIS (Netherlands)

    Lyubovskaya, R.N.; Zhilyaeva, E.I.; Torunova, S.A.; Mousdis, G.A.; Papavassiliou, G.C.; Perenboom, J.A.A.J.; Pesotskii, S.I.; Lyubovskii, R.B.

    2004-01-01

    New ethylenedithiotetrathiafulvalene (EDT-TTF)-based radical cation salts with mercury containing anions of different size and shape have been isolated and studied. Among these compounds the new ambient pressure organic superconductor (EDT-TTF)(4)Hg3-deltaI8, deltasimilar to0.1divided by 0.2, with T

  19. Oceanic Wind Speed and Wind Stress Estimation from Ambient Noise Measurements.

    Science.gov (United States)

    1977-02-01

    it was found that noise records may be used to monitor wind speed and wind stress over the ocean. Time series of wind speeds can be produced from...wind direction, the wind stress has also been estimated and vector-averaged. The monthly mean stress from the authors’ data is higher than values

  20. Time and space variability of spectral estimates of atmospheric pressure

    Science.gov (United States)

    Canavero, Flavio G.; Einaudi, Franco

    1987-01-01

    The temporal and spatial behaviors of atmospheric pressure spectra over the northern Italy and the Alpine massif were analyzed using data on surface pressure measurements carried out at two microbarograph stations in the Po Valley, one 50 km south of the Alps, the other in the foothills of the Dolomites. The first 15 days of the study overlapped with the Alpex Intensive Observation Period. The pressure records were found to be intrinsically nonstationary and were found to display substantial time variability, implying that the statistical moments depend on time. The shape and the energy content of spectra depended on different time segments. In addition, important differences existed between spectra obtained at the two stations, indicating a substantial effect of topography, particularly for periods less than 40 min.

  1. Estimation of pressure drop in gasket plate heat exchangers

    Directory of Open Access Journals (Sweden)

    Neagu Anisoara Arleziana

    2016-06-01

    Full Text Available In this paper, we present comparatively different methods of pressure drop calculation in the gasket plate heat exchangers (PHEs, using correlations recommended in literature on industrial data collected from a vegetable oil refinery. The goal of this study was to compare the results obtained with these correlations, in order to choose one or two for practical purpose of pumping power calculations. We concluded that pressure drop values calculated with Mulley relationship and Buonopane & Troupe correlation were close and also Bond’s equation gave results pretty close to these but the pressure drop is slightly underestimated. Kumar correlation gave results far from all the others and its application will lead to oversize. In conclusion, for further calculations we will chose either the Mulley relationship or the Buonopane & Troupe correlation.

  2. Identity Efficiency for High-Performance Ambient Pressure Ion Mobility Spectrometry.

    Science.gov (United States)

    Kanu, A Bakarr; Leal, Anne

    2016-03-15

    A new approach to reduce the false-positive responses commonly encountered in the field when drugs and explosives are detected is reported for an electrospray ionization high-performance ion mobility spectrometry (ESI-HPIMS). In this article, we report on the combination of reduced mobility and the width-at-half-height of a peak to give a new parameter called conditional reduced mobility (CRM). It was found that the CRM was capable of differentiating between real drugs peaks from that of a false-positive peak and may help to reduce false-positive rates. This effect was demonstrated using 11 drugs (amphetamine, cannabidiol, cocaine, codeine, heroine, methamphetamine, morphine, phentermine, L-phenylepherine, proglitazone, and rosiglitazone) and seven interferences chosen from off-the-shelf products. This report determined and compared CRM, resolving power (R(m)), and diffusion-limited conditional theoretical reduced mobility (DLCTRM) for ESI-HPIMS. The most important parameters for determining CRM are reduced mobility and width-at-half-height of a peak. There is a specific optimum voltage, gate pulse width, resolving power, and now CRM for each ion. DLCTRM indicate the optimum reduced mobility that is not normally possible under field conditions. CRM predicts the condition at which a target compound can be differentiated from a false-positive response. This was possible because different ions exhibits different drifting patterns and hence a different peak broadening phenomenon inside an ion mobility tube. Reduced mobility for target compounds reported were reproducible to within 2% for ESI-HPIMS. The estimated resolving power for the ESI-HPIMS used in this study was 61 ± 0.22. Conditional reduced mobility introduced in this paper show differences between target compounds and false-positive peaks as high as 74%, as was the case for cannabidiol and interference #1 at 70 μs gate pulse width.

  3. Surface Pressure Estimates for Pitching Aircraft Model at High Angles-of-attack (Short Communication

    Directory of Open Access Journals (Sweden)

    A. A. Pashilkar

    2002-10-01

    Full Text Available The surface pressure on a pitching delta wing aircraft is estimated from the normal force and the pitching moment characteristics. The pressure model is based on parametrising the surface pressure distribution on a simple delta wing. This model is useful as a first approximation of the load distribution on the aircraft wing. Leeward surface pressure distributions computed by this method are presented.

  4. Power/Energy Estimator for Designing WSN Nodes with Ambient Energy Harvesting Feature

    Directory of Open Access Journals (Sweden)

    Jutel Dominique

    2011-01-01

    Full Text Available Abstract Wireless Sensor Networks (WSNs consist of spatially distributed autonomous sensors to cooperatively monitor physical conditions. Thus, the node battery autonomy is critical. To outperform it, most WSNs rely on the harvesting capability. As nodes can recharge whenever energy is available, the problem is to determine at design time the node autonomy. For our project, we solve it by creating a power/energy estimator that simulates business scenarios to predict node autonomy; the estimation concerns both power and energy features. Based on node architecture configuration, its Dynamic Power Management (DPM policy, and environmental conditions, we present a simulator that helps identify power consumption hot spots and make critical choices during the system design. It also helps to scale the energy storage system as well as the energy harvesters correctly. The hardware part is modelled using the FLPA methodology to develop different node component models with a variable accuracy. For the logical part, we developped a specific DPM by integrating meteorology and weather forecast behaviours. The novelty comes from the ability to simulate the WSN harvesting capability and to estimate at runtime the remaining duration of each service.

  5. ESTIMATE OF BURSTING PRESSURE OF MILD STEEL PRESSURE VESSEL AND PRESENTATION OF BURSTING FORMULA

    Institute of Scientific and Technical Information of China (English)

    ZHENG Chuanxiang

    2006-01-01

    In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235(Gr.D) and 20R(1020) are done. Based on statistical data of bursting pressure and modification of Faupel formula, a more precise modified formula is given out according to the experimental data. It is proved to be more accurate after examining other bursting pressure value presented in many references. This bursting formula is very accurate in these experiments using pressure vessels with different diameter and shell thickness.Obviously, this modified bursting formula can be used in mild steel pressure vessels with different diameter and thickness of shell.

  6. Inverse-model-based cuffless blood pressure estimation using a single photoplethysmography sensor.

    Science.gov (United States)

    Suzuki, Arata

    2015-07-01

    This paper proposes an inverse-model-based cuffless method for estimating blood pressure using a single photoplethysmography sensor. The proposed method, which is based on the relationship between blood pressure and the features of pulse waves, employs an inverse estimation and uses the blood pressure as the explanatory variable. Using this method, the blood pressure can be estimated with high accuracy even in situations where the pulse wave features are scattered, as the method uses the dynamic signal-to-noise ratio of the Taguchi method. In order to verify the effectiveness of the proposed method, we employed it to measure the systolic blood pressure. It could be confirmed that the estimation accuracy of the proposed method is higher than that of similar methods.

  7. Long-term ambient air pollution exposure and risk of high blood pressure among citizens in Nis, Serbia.

    Science.gov (United States)

    Stanković, Aleksandra; Nikolić, Maja

    2016-01-01

    Epidemiological studies suggest that long-term exposure to air pollution increases the risk for high blood pressure (BP). The aim of our study is to evaluate any effects in BP in citizens exposed to long-term ambient air pollution. The subjects are 1136 citizens, aged 18-70 years, living for more than 5 years in the same home in the areas with a different level of air pollution. The air concentrations of black smoke and sulfur dioxide were determined in the period from 2001 to 2011. We measured systolic and diastolic BP and heart rate. Multivariate methods were used in the analysis. Alcohol consumption had the greatest influence on the incidence of hypertension as a risk factor (RR: 3.461; 95% CI: 1.72-6.93) and age had the least (RR: 1.23; 95% CI: 1.183-1.92). Exposure to air pollution increases risk for developing hypertension 2.5 times (95% CI: 1.46-4.49). Physical activity has proved to be statistically significant protective factor for the development of hypertension. Long-term exposure to low levels of main air pollutants is significantly associated with elevated risk of hypertension.

  8. Characterization of photocatalytic TiO2 powder under varied environments using near ambient pressure X-ray photoelectron spectroscopy

    Science.gov (United States)

    Krishnan, Padmaja; Liu, Minghui; Itty, Pierre A.; Liu, Zhi; Rheinheimer, Vanessa; Zhang, Min-Hong; Monteiro, Paulo J. M.; Yu, Liya E.

    2017-02-01

    Consecutive eight study phases under the successive presence and absence of UV irradiation, water vapor, and oxygen were conducted to characterize surface changes in the photocatalytic TiO2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS). Both Ti 2p and O 1s spectra show hysteresis through the experimental course. Under all the study environments, the bridging hydroxyl (OHbr) and terminal hydroxyl (OHt) are identified at 1.1–1.3 eV and 2.1–2.3 eV above lattice oxygen, respectively. This enables novel and complementary approach to characterize reactivity of TiO2 powder. The dynamic behavior of surface-bound water molecules under each study environment is identified, while maintaining a constant distance of 1.3 eV from the position of water vapor. In the dark, the continual supply of both water vapor and oxygen is the key factor retaining the activated state of the TiO2 powder for a time period. Two new surface peaks at 1.7–1.8 and 4.0–4.2 eV above lattice oxygen are designated as peroxides (OOH/H2O2) and H2O2 dissolved in water, respectively. The persistent peroxides on the powder further explain previously observed prolonged oxidation capability of TiO2 powder without light irradiation.

  9. Synthesis and Thermal Insulation Performance of Silica Aerogel from Recycled Coal Gangue by Means of Ambient Pressure Drying

    Institute of Scientific and Technical Information of China (English)

    ZHU Pinghua; ZHENG Meng; ZHAO Shanyu; WU Junyong; XU Haixun

    2015-01-01

    Silica aerogel materials are well recognized for their superinsulation performance and are regarded as one of the hot candidates to revolutionize building insulation. To date, high production cost related to exorbitant precursors as well as cumbrous multi-step hydrophobization process has often narrowed the ifeld of applications. In this work, granular silica aerogel materials were synthesized by extracting SiO2from recycled rich silicon coal gangue, followed by one-step hydrophobization and ambient pressure drying. Lightweight (about 0.16 g/cm3) and nanostructural aerogels were obtained through this route. They exhibit a 3D open porous microstructure with around 600 cm2/g surface area and 20 nm of the average pore diameter, thermal conductivity of 4-5 mm packed granules is 20-25 mW/(m·K), which was proved by both guarded hot plate and hot-wire transient methods. This study offers a new facile route for the synthesis of silica aerogel from recycled solid waste coal gangue and suggests a method, which may lead to a cost reduction in terms of industrial production.

  10. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy of Cobalt Perovskite Surfaces under Cathodic Polarization at High Temperatures

    KAUST Repository

    Crumlin, Ethan J.

    2013-08-08

    Heterostructured oxide interfaces have demonstrated enhanced oxygen reduction reaction rates at elevated temperatures (∼500-800 C); however, the physical origin underlying this enhancement is not well understood. By using synchrotron-based in situ ambient pressure X-ray photoelectron spectroscopy (APXPS), we focus on understanding the surface electronic structure, elemental composition, and chemical nature of epitaxial La0.8Sr 0.2CoO3-δ (LSC113), (La 0.5Sr0.5)2CoO4±δ (LSC214), and LSC214-decorated LSC113 (LSC 113/214) thin films as a function of applied electrical potentials (0 to -800 mV) at 520 C and p(O2) of 1 × 10-3 atm. Shifts in the top of the valence band binding energy and changes in the Sr 3d and O 1s spectral components under applied bias reveal key differences among the film chemistries, most notably in the degree of Sr segregation to the surface and quantity of active oxygen sites in the perovskite termination layer. These differences help to identify important factors governing the enhanced activity of oxygen electrocatalysis observed for the LSC113/214 heterostructured surface. © 2013 American Chemical Society.

  11. Characterization of photocatalytic TiO2 powder under varied environments using near ambient pressure X-ray photoelectron spectroscopy

    Science.gov (United States)

    Krishnan, Padmaja; Liu, Minghui; Itty, Pierre A.; Liu, Zhi; Rheinheimer, Vanessa; Zhang, Min-Hong; Monteiro, Paulo J. M.; Yu, Liya E.

    2017-01-01

    Consecutive eight study phases under the successive presence and absence of UV irradiation, water vapor, and oxygen were conducted to characterize surface changes in the photocatalytic TiO2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS). Both Ti 2p and O 1s spectra show hysteresis through the experimental course. Under all the study environments, the bridging hydroxyl (OHbr) and terminal hydroxyl (OHt) are identified at 1.1–1.3 eV and 2.1–2.3 eV above lattice oxygen, respectively. This enables novel and complementary approach to characterize reactivity of TiO2 powder. The dynamic behavior of surface-bound water molecules under each study environment is identified, while maintaining a constant distance of 1.3 eV from the position of water vapor. In the dark, the continual supply of both water vapor and oxygen is the key factor retaining the activated state of the TiO2 powder for a time period. Two new surface peaks at 1.7–1.8 and 4.0–4.2 eV above lattice oxygen are designated as peroxides (OOH/H2O2) and H2O2 dissolved in water, respectively. The persistent peroxides on the powder further explain previously observed prolonged oxidation capability of TiO2 powder without light irradiation. PMID:28240300

  12. Reactivity of Au nanoparticles supported over SiO2 and TiO2 studiedby ambient pressure photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, Tirma; Deng, Xingyi; Cabot, Andreu; Alivisatos, Paul; Liu, Zhi; Soler-Illia, Galo; Salmeron, Miquel

    2009-04-15

    The influence of the metal cluster size and the identity of the support on the reactivity of gold based catalysts have been studied in the CO oxidation reaction. To overcome the structural complexity of the supported catalysts, gold nanoparticles synthesized from colloidal chemistry with precisely controlled size have been used. Those particles were supported over SiO{sub 2} and TiO{sub 2} and their catalytic activity was measured in a flow reactor. The reaction rate was dependent on the particle size and the support, suggesting two reaction pathways in the CO oxidation reaction. In parallel, ambient pressure photoelectron spectroscopy (APPS) has been performed under reaction conditions using bidimensional model catalysts prepared upon supporting the Au nanoparticles over planar polycrystalline SiO{sub 2} and TiO{sub 2} thin films by means of the Langmuir-Blodgett (LB) technique to mimic the characteristic of the powder samples. In this way, the catalytically active surface was characterized under true reaction conditions, revealing that during CO oxidation gold remains in the metallic state.

  13. Challenges in estimating insecticide selection pressures from mosquito field data.

    Directory of Open Access Journals (Sweden)

    Susana Barbosa

    2011-11-01

    Full Text Available Insecticide resistance has the potential to compromise the enormous effort put into the control of dengue and malaria vector populations. It is therefore important to quantify the amount of selection acting on resistance alleles, their contributions to fitness in heterozygotes (dominance and their initial frequencies, as a means to predict the rate of spread of resistance in natural populations. We investigate practical problems of obtaining such estimates, with particular emphasis on Mexican populations of the dengue vector Aedes aegypti. Selection and dominance coefficients can be estimated by fitting genetic models to field data using maximum likelihood (ML methodology. This methodology, although widely used, makes many assumptions so we investigated how well such models perform when data are sparse or when spatial and temporal heterogeneity occur. As expected, ML methodologies reliably estimated selection and dominance coefficients under idealised conditions but it was difficult to recover the true values when datasets were sparse during the time that resistance alleles increased in frequency, or when spatial and temporal heterogeneity occurred. We analysed published data on pyrethroid resistance in Mexico that consists of the frequency of a Ile1,016 mutation. The estimates for selection coefficient and initial allele frequency on the field dataset were in the expected range, dominance coefficient points to incomplete dominance as observed in the laboratory, although these estimates are accompanied by strong caveats about possible impact of spatial and temporal heterogeneity in selection.

  14. Estimation of the effects of ambient air pollution on life expectancy of urban residents in China

    Science.gov (United States)

    Wang, Cuicui; Zhou, Xiaodan; Chen, Renjie; Duan, Xiaoli; Kuang, Xingya; Kan, Haidong

    2013-12-01

    The air quality in China's cities has improved in recent years, but its impact on public health has rarely been investigated. This study was aimed at estimating the potential effects of air quality on life expectancy between 2003 and 2010 in China. We collected annual average concentrations of particulate matter less than 10 microns in aerodynamic diameter (PM10) in 113 key cities, covering all provinces in China, along with the national average age-specific mortality from 2003 to 2010. We constructed a cause-eliminated life table after excluding premature deaths attributable to PM10. The annual average PM10 levels in these cities decreased from 125.3 μg m-3 in 2003 to 88.3 μg m-3 in 2010. As the result, life expectancy loss due to PM10 decreased from 2.13 years in 2003 to 1.30 years in 2010. The estimated life expectancy increase due to PM10 mitigation accounted for 34% of the total increase in life expectancy in the same period. Our results suggested that air quality might have contributed substantially to life expectancy in China.

  15. Development of open air silicon deposition technology by silane-free atmospheric pressure plasma enhanced chemical transport under local ambient gas control

    Science.gov (United States)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2016-07-01

    Open air silicon deposition was performed by combining silane-free atmospheric pressure plasma-enhanced chemical transport and a newly developed local ambient gas control technology. The effect of air contamination on silicon deposition was investigated using a vacuum chamber, and the allowable air contamination level was confirmed to be 3 ppm. The capability of the local ambient gas control head was investigated numerically and experimentally. A safe and clean process environment with air contamination less than 1 ppm was achieved. Combining these technologies, a microcrystalline silicon film was deposited in open air, the properties of which were comparable to those of silicon films deposited in a vacuum chamber.

  16. In Situ Studies of Surface Mobility on Noble Metal Model Catalysts Using STM and XPS at Ambient Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Butcher, Derek Robert [Univ. of California, Berkeley, CA (United States)

    2010-06-01

    High Pressure Scanning Tunneling Microscopy (HP-STM) and Ambient Pressure X-ray Photoelectron Spectroscopy were used to study the structural properties and catalytic behavior of noble metal surfaces at high pressure. HP-STM was used to study the structural rearrangement of the top most atomic surface layer of the metal surfaces in response to changes in gas pressure and reactive conditions. AP-XPS was applied to single crystal and nanoparticle systems to monitor changes in the chemical composition of the surface layer in response to changing gas conditions. STM studies on the Pt(100) crystal face showed the lifting of the Pt(100)-hex surface reconstruction in the presence of CO, H2, and Benzene. The gas adsorption and subsequent charge transfer relieves the surface strain caused by the low coordination number of the (100) surface atoms allowing the formation of a (1 x 1) surface structure commensurate with the bulk terminated crystal structure. The surface phase change causes a transformation of the surface layer from hexagonal packing geometry to a four-fold symmetric surface which is rich in atomic defects. Lifting the hex reconstruction at room temperature resulted in a surface structure decorated with 2-3 nm Pt adatom islands with a high density of step edge sites. Annealing the surface at a modest temperature (150 C) in the presence of a high pressure of CO or H2 increased the surface diffusion of the Pt atoms causing the adatom islands to aggregate reducing the surface concentration of low coordination defect sites. Ethylene hydrogenation was studied on the Pt(100) surface using HP-STM. At low pressure, the lifting of the hex reconstruction was observed in the STM images. Increasing the ethylene pressure to 1 Torr, was found to regenerate the hexagonally symmetric reconstructed phase. At room temperature ethylene undergoes a structural rearrangement to form ethylidyne. Ethylidyne preferentially binds at the three-fold hollow sites, which

  17. Effect of random errors in planar PIV data on pressure estimation in vortex dominated flows

    Science.gov (United States)

    McClure, Jeffrey; Yarusevych, Serhiy

    2015-11-01

    The sensitivity of pressure estimation techniques from Particle Image Velocimetry (PIV) measurements to random errors in measured velocity data is investigated using the flow over a circular cylinder as a test case. Direct numerical simulations are performed for ReD = 100, 300 and 1575, spanning laminar, transitional, and turbulent wake regimes, respectively. A range of random errors typical for PIV measurements is applied to synthetic PIV data extracted from numerical results. A parametric study is then performed using a number of common pressure estimation techniques. Optimal temporal and spatial resolutions are derived based on the sensitivity of the estimated pressure fields to the simulated random error in velocity measurements, and the results are compared to an optimization model derived from error propagation theory. It is shown that the reductions in spatial and temporal scales at higher Reynolds numbers leads to notable changes in the optimal pressure evaluation parameters. The effect of smaller scale wake structures is also quantified. The errors in the estimated pressure fields are shown to depend significantly on the pressure estimation technique employed. The results are used to provide recommendations for the use of pressure and force estimation techniques from experimental PIV measurements in vortex dominated laminar and turbulent wake flows.

  18. A method for variable pressure load estimation in spur and helical gear pumps

    Science.gov (United States)

    Battarra, M.; Mucchi, E.

    2016-08-01

    A systematic procedure is proposed to determine variable excitation loads coming from pressure evolution inside tooth spaces in external gear pumps. Pressure force and torque are estimated with respect to the angular position of the gears, taking into account the phenomena that occur during the meshing course. In particular, the paper proposes a general methodology aiming at determining pressure force and torque components along the three coordinate axes and suitable to be applied on both spur and helical gear configuration. Firstly, the method to calculate pressure loads acting on a single tooth space during a complete revolution is given, then the total pressure force and torque loading each gear is obtained. Particular attention is addressed on the description of the helical gear scenario. As an example, the method is applied to a tandem gear pump, characterized by the presence of two stages, one with spur gears and one with helical gears. An experimentally assessed model to calculate the pressure ripple inside the tandem pump is described and the proposed procedure for pressure load estimation is applied. Eventually, the pressure loads estimated with the present procedure are compared with other estimation methods already described in the literature. The comparison shows that the present methodology is able to describe a wider range of phenomena involved in the meshing evolution and to determine all the pressure force and torque components applied to helical gears. The method gives suitable results to study the balancing and the dynamic behavior of gear pumps.

  19. Transepidermal water loss in newborn infants. I. Relation to ambient humidity and site of measurement and estimation of total transepidermal water loss.

    Science.gov (United States)

    Hammarl-nd, K; Nilsson, G E; Oberg, P A; Sedin, G

    1977-09-01

    Insensible water loss (IWL) is an important factor in the thermoregulation and water balance of the newborn infant. A method for direct measurement of the rate of evaporation from the skin surface has been developed. The method, which is based on determination of the vapour pressure gradient close to the skin surface, allows free evaporation. From measurements performed on 19 newborns placed in incubators, a linear relation was found between the evaporation rate (ER) and the humidity of the environment at a constant ambient temperature. A 40% lower ER was recorded at a high relative humidity (60%) than at a low one (20%) in the incubator. At measurements on different sites of the body, a high ER was observed on the face and peripheral parts of the extremities, while ER at other sites was relatively low. By determining ER from different parts of the body and calculating the areas of the corresponding surfaces, the total cutaneous insensible water loss for the infant in question could be obtained. The transepidermal water loss (TEWL) for the whole body surface area was calculated to be 8.1 g/m2h. On the basis of measurements performed it was found that the total cutaneous insensible water loss can be estimated with a reasonable degree of accuracy by recording ER from only three easily accessible measurement points.

  20. Effects of ambient and acute partial pressures of ozone on leaf net CO sub 2 assimilation of field-grown Vitis vinifera L

    Energy Technology Data Exchange (ETDEWEB)

    Roper, T.R.; Williams, L.E. (Univ. of California, Davis (USA) Kearney Agricultural Center, Parlier, CA (USA))

    1989-12-01

    Mature, field-grown Vitis vinifera L. grapevines grown in open-top chambers were exposed to either charcoal-filtered air or ambient ozone partial pressures throughout the growing season. Individual leaves also were exposed to ozone partial pressures of 0.2, 0.4, or 0.6 micropascals per pascal for 5 hours. No visual ozone damage was found on leaves exposed to any of the treatments. Chronic exposure to ambient O{sub 3} partial pressures reduced net CO{sub 2} assimilation rate (A) between 5 and 13% at various times throughout the season when compared to the filtered treatment. Exposure of leaves to 0.2 micropascals per pascal O{sub 3} for 5 hours had no significant effect on A; however, A was reduced 84% for leaves exposed to 0.6 micropascals per pascal O{sub 3} when compared to the controls after 5 hours. Intercellular CO{sub 2} partial pressure (c{sub i}) was lower for leaves exposed to 0.2 micropascals per pascal O{sub 3} when compared to the controls, while c{sub i} of the leaves treated with 0.6 micropascals per pascal of O{sub 3} increased during the fumigation. The long-term effects of ambient O{sub 3} and short-term exposure to acute levels of O{sub 3} reduced grape leaf photosynthesis due to a reduction in both stomatal and mesophyll conductances.

  1. Age-related effects of increased ambient pressure on discrimination reaction time: A study in 105 professional divers at 6.0 atm abs.

    Science.gov (United States)

    Tikkinen, Janne; Siimes, Martti A

    2015-01-01

    We investigated 105 professional divers using a computerized visual discrimination trial (Cognitrone) to measure the effects of ambient pressure on reaction times. The possible improvement in performance due to practice was anticipated, and the trials were carried out four times prior to pressurization in a hyperbaric chamber. The effect of increased ambient pressure was measured at 6.0 and 1.9 atm abs, and the potential for residual effects was tested after decompression. The results of our study indicate that repeated testing had a systematic influence on the measured time values. The effects of learning, which were independent of diver age, may have independently influenced response times. Exposure to 6.0 atm abs modified the systematic pattern of learning and was associated with increased reaction times. There were also age-related differences in response times associated with exposure to increased ambient pressures. Younger divers were more susceptible to elevated ambient pressure, evidenced by increased response times at 6 atm abs relative to their older colleagues. One out of every four of the younger divers could be considered susceptible to inert gas narcosis (ION) when an increase of one standard deviation/1SD (> 19%) or more in discrimination reaction time is used as an indicator. ION susceptibility appears independent of body composition and physical fitness. The slowed response speed experienced at 6.0 atm abs was of short duration and returned to baseline immediately with decompression. Our results suggest that IGN is demonstrated by an impaired learning process and decreased response speed and that some younger divers appear more susceptible.

  2. Noninvasive estimation of 2-D pressure gradients in steady flow using ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Traberg, Marie Sand; Pihl, Michael Johannes;

    2014-01-01

    A noninvasive method for estimating 2-D pressure gradients from ultrasound vector velocity data is presented. It relies on vector velocity fields acquired using the transverse oscillation method during steady flow conditions. The pressure gradients are calculated from the velocity fields using...... of -7% for the axial component and -8% for the lateral component. The relative standard deviation of the estimator is 5% (axial component) and 30% (lateral component) when studying the pressure gradient across the constriction using 3 velocity frames per pressure estimate. The study shows that 2-D...... phantom. The geometry of the model is determined from magnetic resonance imaging. The presented study is conducted assuming steady flow using velocity data acquired at 18 frames per second. The proposed method shows pressure gradients at the constricted region from -8 kPa/m to 9 kPa/m, with a maximum bias...

  3. Estimation of the left ventricular relaxation time constant tau requires consideration of the pressure asymptote.

    Science.gov (United States)

    Langer, S F J; Habazettl, H; Kuebler, W M; Pries, A R

    2005-01-01

    The left ventricular isovolumic pressure decay, obtained by cardiac catheterization, is widely characterized by the time constant tau of the exponential regression p(t)=Pomega+(P0-Pomega)exp(-t/tau). However, several authors prefer to prefix Pomega=0 instead of coestimating the pressure asymptote empirically; others present tau values estimated by both methods that often lead to discordant results and interpretation of lusitropic changes. The present study aims to clarify the relations between the tau estimates from both methods and to decide for the more reliable estimate. The effect of presetting a zero asymptote on the tau estimate was investigated mathematically and empirically, based on left ventricular pressure decay data from isolated ejecting rat and guinea pig hearts at different preload and during spontaneous decrease of cardiac function. Estimating tau with preset Pomega=0 always yields smaller values than the regression with empirically estimated asymptote if the latter is negative and vice versa. The sequences of tau estimates from both methods can therefore proceed in reverse direction if tau and Pomega change in opposite directions between the measurements. This is exemplified by data obtained during an increasing preload in spontaneously depressed isolated hearts. The estimation of the time constant of isovolumic pressure fall with a preset zero asymptote is heavily biased and cannot be used for comparing the lusitropic state of the heart in hemodynamic conditions with considerably altered pressure asymptotes.

  4. Estimated daily salt intake in relation to blood pressure and blood lipids

    DEFF Research Database (Denmark)

    Thuesen, Betina H; Toft, Ulla; Buhelt, Lone P

    2015-01-01

    BACKGROUND: Excessive salt intake causes increased blood pressure which is considered the leading risk for premature death. One major challenge when evaluating associations between daily salt intake and markers of non-communicable diseases is that a high daily salt intake correlates with obesity......, which is also a well described risk factor for poor cardiometabolic outcome. The aim of this study was to evaluate the relationship of estimated daily salt intake with blood pressure and blood lipids and to investigate the effect of taking different measures of obesity into account. METHODS: We included...... of estimated 24-hour sodium excretion with blood pressure and blood lipids were evaluated by linear regression models. RESULTS: The daily mean estimated intake of salt was 10.80 g and 7.52 g among men and women, respectively. Daily salt intake was significantly associated with blood pressure (β-estimates 1...

  5. A new route for preparation of sodium-silicate-based hydrophobic silica aerogels via ambient-pressure drying

    Directory of Open Access Journals (Sweden)

    Uzma K H Bangi, A Venkateswara Rao and A Parvathy Rao

    2008-01-01

    Full Text Available An in-depth investigation into the synthesis of hydrophobic silica aerogels prepared by the surface derivatization of wet gels followed by subsequent drying at ambient pressure is reported. The following sol–gel parameters were examined for their effect on the physical properties of the derived aerogels: number of gel washings with water, percentage of hexane or methanol in silylating mixture, molar ratio of tartaric acid: Na2SiO3, gel aging period, weight% of silica, trimethylchlorosilane (TMCS percentage, and silylation period. These parameters were varied from 1 to 4, 0 to 100%, 0.27 to 1.2, 0 to 4 h, 1.5 to 8 wt.%, 20 to 40% and 6 to 24 h, respectively. The properties of hydrophobic silica aerogels synthesized by this new route were investigated in terms of bulk density, percentage volume shrinkage, percentage porosity, thermal conductivity and contact angle with water, and by Fourier transform infrared spectroscopy (FTIR. The as-prepared hydrophobic silica aerogels exhibited high temperature stability (up to approximately 435 °C as measured by thermogravimetric/differential thermal analysis (TGA-DTA. The optimal sol-gel parameters were found to be a molar ratio of Na2SiO3:H2O : tartaric acid : TMCS of 1 : 146.67 : 0.86 : 9.46, an aging period of 3 h, four washings with water in 24 h and the use of a 50% hexane- or methanol-based silylating mixture. Aerogels prepared with these optimal parameters were found to exhibit 50% optical transparency in the visible range, 84 kg m−3 density, 0.090 W mK−1 thermal conductivity, 95% porosity and a contact angle of 146° with water.

  6. Structural phase transitions and superconductivity in Fe(1+delta)Se0.57Te0.43 at ambient and elevated pressures.

    Science.gov (United States)

    Gresty, Nathalie C; Takabayashi, Yasuhiro; Ganin, Alexey Y; McDonald, Martin T; Claridge, John B; Giap, Duong; Mizuguchi, Yoshikazu; Takano, Yoshihiko; Kagayama, Tomoko; Ohishi, Yasuo; Takata, Masaki; Rosseinsky, Matthew J; Margadonna, Serena; Prassides, Kosmas

    2009-11-25

    The ternary iron chalcogenide, Fe(1.03)Se(0.57)Te(0.43) is a member of the recently discovered family of Fe-based superconductors with an ambient pressure T(c) of 13.9 K and a simple structure comprising layers of edge-sharing distorted Fe(Se/Te)(4) tetrahedra separated by a van der Waals gap. Here we study the relationship between its structural and electronic responses to the application of pressure. T(c) depends sensitively on applied pressure attaining a broad maximum of 23.3 K at approximately 3 GPa. Further compression to 12 GPa leads to a metallic but nonsuperconducting ground state. High-resolution synchrotron X-ray diffraction shows that the superconducting phase is metrically orthorhombic at ambient pressure but pressurization to approximately 3 GPa leads to a structural transformation to a more distorted structure with monoclinic symmetry. The exact coincidence of the crystal symmetry crossover pressure with that at which T(c) is maximum reveals an intimate link between crystal and electronic structures of the iron chalcogenide superconductors.

  7. Physical properties of sodium silicate based silica aerogels prepared by single step sol-gel process dried at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gurav, Jyoti L. [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India); Rao, A. Venkateswara [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India)], E-mail: raouniv@yahoo.com; Rao, A. Parvathy; Nadargi, D.Y.; Bhagat, S.D. [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, Maharashtra (India)

    2009-05-12

    The experimental results on physical properties of water glass (sodium silicate) based silica aerogels prepared by single step sol-gel process, dried at atmospheric pressure are reported. The hydrolysis and condensation reactions of the sodium silicate precursor proceeded with tartaric acid as a catalyst. The hydrogel was vapour passed in order to remove sodium salt from the gel network. Solvent exchange was carried out using methanol and hexane as a solvents. Finally, surface chemical modification of the gel was done using trimethylchlorosilane (TMCS) followed by ambient pressure drying of the gel up to the temperature 200 deg. C. To get good quality aerogels various sol-gel parameters such as water vapour passing period varied from 0.5 to 2 h, gel aging from 1 to 4 h, Na{sub 2}SiO{sub 3}/H{sub 2}O molar ratio from 3 x 10{sup -3} to 1.5 x 10{sup -2}, tartaric acid/Na{sub 2}SiO{sub 3} molar ratio from 0.3 to 1.9 and TMCS/Na{sub 2}SiO{sub 3} molar ratio from 4.8 to 12. The aerogels were characterized by percentage of volume shrinkage, bulk density, porosity and hydrophobicity. The hydrophobicity of the aerogel was confirmed by Fourier Transform Infrared (FTIR) Spectroscopy and contact angle measurements. Microstructural studies have been carried out by Scanning Electron Microscopy (SEM) and nitrogen adsorption BET analysis. From the TGA-DTA studies of the aerogels, it was found that the aerogels were thermally stable up to 470 {sup o}C. Low density ({approx}0.066 g/cm{sup 3}), high hydrophobicity ({approx}145 deg.), high porosity ({approx}97 %), high pore volume, surface area of 510 m{sup 2}/g aerogels have been obtained for Na{sub 2}SiO{sub 3}:H{sub 2}O:tartaric acid (C{sub 4}H{sub 6}O{sub 6}):TMCS molar ratio at 1:166.6:2.5:12 respectively with half an hour water vapour passing.

  8. Fundamentals of ionic conductivity relaxation gained from study of procaine hydrochloride and procainamide hydrochloride at ambient and elevated pressure.

    Science.gov (United States)

    Wojnarowska, Z; Swiety-Pospiech, A; Grzybowska, K; Hawelek, L; Paluch, M; Ngai, K L

    2012-04-28

    The pharmaceuticals, procaine hydrochloride and procainamide hydrochloride, are glass-forming as well as ionically conducting materials. We have made dielectric measurements at ambient and elevated pressures to characterize the dynamics of the ion conductivity relaxation in these pharmaceuticals, and calorimetric measurements for the structural relaxation. Perhaps due to their special chemical and physical structures, novel features are found in the ionic conductivity relaxation of these pharmaceuticals. Data of conductivity relaxation in most ionic conductors when represented by the electric loss modulus usually show a single resolved peak in the electric modulus loss M(")(f) spectra. However, in procaine hydrochloride and procainamide hydrochloride we find in addition another resolved loss peak at higher frequencies over a temperature range spanning across T(g). The situation is analogous to many non-ionic glass-formers showing the presence of the structural α-relaxation together with the Johari-Goldstein (JG) β-relaxation. Naturally the analogy leads us to name the slower and faster processes resolved in procaine hydrochloride and procainamide hydrochloride as the primary α-conductivity relaxation and the secondary β-conductivity relaxation, respectively. The analogy of the β-conductivity relaxation in procaine HCl and procainamide HCl with JG β-relaxation in non-ionic glass-formers goes further by the finding that the β-conductivity is strongly related to the α-conductivity relaxation at temperatures above and below T(g). At elevated pressure but compensated by raising temperature to maintain α-conductivity relaxation time constant, the data show invariance of the ratio between the β- and the α-conductivity relaxation times to changes of thermodynamic condition. This property indicates that the β-conductivity relaxation has fundamental importance and is indispensable as the precursor of the α-conductivity relaxation, analogous to the relation found

  9. Use of Cokriging to Improve Spatial Resolution of Ambient Airborne Contaminant Concentration Estimates in Detroit and Windsor

    Science.gov (United States)

    Lemke, L. D.; Bobryk, S. M.; Xu, X.

    2010-12-01

    A combination of active and passive air sampling devices was deployed to measure ambient air quality over a two-week period during September 2008 in Detroit, Michigan, USA and Windsor, Ontario, Canada. Passive diffusion monitors were used to measure nitrogen dioxide (NO2), sulfur dioxide (SO2) and 26 volatile organic compounds (VOCs) at 100 sampling sites with an approximate spacing of 1 per 5 km2. Active samplers utilizing a pump were collocated at 50 of the passive sites to sample particulate matter (PM) and 23 polycyclic aromatic hydrocarbons (PAHs) at an approximate sample density of 1 per 10 km2. The field campaign yielded acceptable data at 98 of the 100 passive monitoring sites. However, pump failures and power outages limited acceptable data to only 38 out of 50 active sites and the intended spatial coverage was not achieved. The utility of cokriging was therefore investigated as a means of improving PAH and PM concentration estimates by using more densely spaced passive sampler analyte concentrations as secondary information. Moderate positive correlation coefficients (panalysis was performed to specify the cross-covariance structure between each pair of pollutants using a linear model of coregionalization. Concentration maps produced through both ordinary kriging (OK) and ordinary cokriging (OCK) were compared and statistical metrics were used to quantify improvement in estimates for sampled points attributable to cokriging. Scatter plots of measured vs. estimated values indicate that both OK and OCK were able to reliably predict concentrations near measurement points. Modest improvement in cross validation correlation coefficients and residual error statistics were observed for PAH cokriged with NO2 and benzene; however, predictive performance for PM1-2.5 cokriged with NO2 was slightly degraded. Nevertheless, mapped results demonstrate that PAH and PM1-2.5 concentration surfaces generated with OCK maps have improved spatial resolution over OK maps and

  10. Subharmonic contrast microbubble signals for noninvasive pressure estimation under static and dynamic flow conditions.

    Science.gov (United States)

    Halldorsdottir, Valgerdur G; Dave, Jaydev K; Leodore, Lauren M; Eisenbrey, John R; Park, Suhyun; Hall, Anne L; Thomenius, Kai; Forsberg, Flemming

    2011-07-01

    Our group has proposed the concept of subharmonic aided pressure estimation (SHAPE) utilizing microbubble-based ultrasound contrast agent signals for the noninvasive estimation of hydrostatic blood pressures. An experimental system for in vitro SHAPE was constructed based on two single-element transducers assembled confocally at a 60 degree angle to each other. Changes in the first, second and subharmonic amplitudes of five different ultrasound contrast agents were measured in vitro at static hydrostatic pressures from 0-186 mmHg, acoustic pressures from 0.35-0.60 MPa peak-to-peak and frequencies of 2.5-6.6 MHz. The most sensitive agent and optimal parameters for SHAPE were determined using linear regression analysis and implemented on a Logiq 9 scanner (GE Healthcare, Milwaukee, WI). This implementation of SHAPE was then tested under dynamic-flow conditions and compared to pressure-catheter measurements. Over the pressure range studied, the first and second harmonic amplitudes reduced approximately 2 dB for all contrast agents. Over the same pressure range, the subharmonic amplitudes decreased by 9-14 dB and excellent linear regressions were achieved with the hydrostatic pressure variations (r = 0.98, p scanner was modified to implement SHAPE on a convex transducer with a frequency range from 1.5-4.5 MHz and acoustic pressures from 0-3.34 MPa. Results matched the pressure catheter (r2 = 0.87). In conclusion, subharmonic contrast signals are a good indicator of hydrostatic pressure. Out of the five ultrasound contrast agents tested, Sonazoid was the most sensitive for subharmonic pressure estimation. Real-time SHAPE has been implemented on a commercial scanner and offers the possibility of allowing pressures in the heart and elsewhere to be obtained noninvasively.

  11. Estimation of trapped mass by in-cylinder pressure resonance in HCCI engines

    Science.gov (United States)

    Luján, José Manuel; Guardiola, Carlos; Pla, Benjamín; Bares, Pau

    2016-01-01

    High pressure gradients at homogeneous charge compression ignition (HCCI) engines heavily excite the pressure resonance. The pressure resonant frequency depends on speed of sound in the cylinder, and thus on the bulk gas temperature. Present paper profits this relation estimating the trapped mass inside the cylinder. In contrast to other estimation methods in the literature, the presented method is based on the trace of the in-cylinder pressure during the cycle; therefore, it permits a cycle-to-cycle mass estimation, and avoids errors associated with other assumptions, such as heat transfer during compression or initial temperature of the in-cylinder gases. The proposed strategy only needs the pressure signal, a volume estimation and a composition assumption to obtain several trapped mass estimates during one cycle. These estimates can be later combined for providing an error estimate of the measurement, with the assumption of negligible blow-by. The method is demonstrated in two HCCI engines of different size, showing good performance in steady operation and presenting great potential to control transient operation.

  12. SU-E-T-365: Estimation of Neutron Ambient Dose Equivalents for Radioprotection Exposed Workers in Radiotherapy Facilities Based On Characterization Patient Risk Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Irazola, L; Terron, J; Sanchez-Doblado, F [Departamento de Fisiologia Medica y Biofisica, Universidad de Sevilla (Spain); Servicio de Radiofisica, Hospital Universitario Virgen Macarena, Sevilla (Spain); Domingo, C; Romero-Exposito, M [Departament de Fisica, Universitat Autonoma de Barcelona, Bellaterra (Spain); Garcia-Fuste, M [Health and Safety Department, ALBA Synchrotron Light Source, Cerdanyola del Valles (Spain); Sanchez-Nieto, B [Instituto de Fisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Bedogni, R [Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN) (Italy)

    2015-06-15

    Purpose: Previous measurements with Bonner spheres{sup 1} showed that normalized neutron spectra are equal for the majority of the existing linacs{sup 2}. This information, in addition to thermal neutron fluences obtained in the characterization procedure{sup 3}3, would allow to estimate neutron doses accidentally received by exposed workers, without the need of an extra experimental measurement. Methods: Monte Carlo (MC) simulations demonstrated that the thermal neutron fluence distribution inside the bunker is quite uniform, as a consequence of multiple scatter in the walls{sup 4}. Although inverse square law is approximately valid for the fast component, a more precise calculation could be obtained with a generic fast fluence distribution map around the linac, from MC simulations{sup 4}. Thus, measurements of thermal neutron fluences performed during the characterization procedure{sup 3}, together with a generic unitary spectra{sup 2}, would allow to estimate the total neutron fluences and H*(10) at any point{sup 5}. As an example, we compared estimations with Bonner sphere measurements{sup 1}, for two points in five facilities: 3 Siemens (15–23 MV), Elekta (15 MV) and Varian (15 MV). Results: Thermal neutron fluences obtained from characterization, are within (0.2–1.6×10{sup 6}) cm−{sup 2}•Gy{sup −1} for the five studied facilities. This implies ambient equivalent doses ranging from (0.27–2.01) mSv/Gy 50 cm far from the isocenter and (0.03–0.26) mSv/Gy at detector location with an average deviation of ±12.1% respect to Bonner measurements. Conclusion: The good results obtained demonstrate that neutron fluence and H*(10) can be estimated based on: (a) characterization procedure established for patient risk estimation in each facility, (b) generic unitary neutron spectrum and (c) generic MC map distribution of the fast component. [1] Radiat. Meas (2010) 45: 1391 – 1397; [2] Phys. Med. Biol (2012) 5 7:6167–6191; [3] Med. Phys (2015) 42

  13. Noninvasive average flow and differential pressure estimation for an implantable rotary blood pump using dimensional analysis.

    Science.gov (United States)

    Lim, Einly; Karantonis, Dean M; Reizes, John A; Cloherty, Shaun L; Mason, David G; Lovell, Nigel H

    2008-08-01

    Accurate noninvasive average flow and differential pressure estimation of implantable rotary blood pumps (IRBPs) is an important practical element for their physiological control. While most attempts at developing flow and differential pressure estimate models have involved purely empirical techniques, dimensional analysis utilizes theoretical principles of fluid mechanics that provides valuable insights into parameter relationships. Based on data obtained from a steady flow mock loop under a wide range of pump operating points and fluid viscosities, flow and differential pressure estimate models were thus obtained using dimensional analysis. The algorithm was then validated using data from two other VentrAssist IRBPs. Linear correlations between estimated and measured pump flow over a flow range of 0.5 to 8.0 L/min resulted in a slope of 0.98 ( R(2) = 0.9848). The average flow error was 0.20 +/- 0.14 L/min (mean +/- standard deviation) and the average percentage error was 5.79%. Similarly, linear correlations between estimated and measured pump differential pressure resulted in a slope of 1.027 ( R(2) = 0.997) over a pressure range of 60 to 180 mmHg. The average differential pressure error was 1.84 +/- 1.54 mmHg and the average percentage error was 1.51%.

  14. An Estimate of the Thermodynamic Pressure in High-Energy Collisions

    CERN Document Server

    Tawfik, Abdel Nasser

    2015-01-01

    We introduce a novel approach to estimate the thermodynamic pressure from heavy-ion collisions based on recently measured higher-order moments of particle multiplicities by the STAR experiment. We start with fitting the experimental results in the most-central collisions. Then, we integrate them back to lower ones. For example, we find that the first-order moment, the mean multiplicity, is exactly reproduced from the integral of variance, the second-order moment. Therefore, the zero-order moment, the thermodynamic pressure, can be estimated from the integral of the mean multiplicity. the possible comparison between such a kind of pressure (deduced from the integral of particle multiplicity) and the lattice pressure and the relating of Bjorken energy density to the lattice energy density are depending on lattice QCD at finite baryon chemical potential and first-principle estimation of the formation time of the quark-gluon plasma (QGP).

  15. Ambient pressure structural quantum critical point in the phase diagram of (Ca(x)Sr(1-x))(3)Rh(4)Sn(13).

    Science.gov (United States)

    Goh, S K; Tompsett, D A; Saines, P J; Chang, H C; Matsumoto, T; Imai, M; Yoshimura, K; Grosche, F M

    2015-03-06

    The quasiskutterudite superconductor Sr_{3}Rh_{4}Sn_{13} features a pronounced anomaly in electrical resistivity at T^{*}∼138  K. We show that the anomaly is caused by a second-order structural transition, which can be tuned to 0 K by applying physical pressure and chemical pressure via the substitution of Ca for Sr. A broad superconducting dome is centered around the structural quantum critical point. Detailed analysis of the tuning parameter dependence of T^{*} as well as insights from lattice dynamics calculations strongly support the existence of a structural quantum critical point at ambient pressure when the fraction of Ca is 0.9 (i.e., x_{c}=0.9). This establishes the (Ca_{x}Sr_{1-x})_{3}Rh_{4}Sn_{13} series as an important system for exploring the physics of structural quantum criticality without the need of applying high pressures.

  16. Application of quantitative structure-property relationship analysis to estimate the vapor pressure of pesticides.

    Science.gov (United States)

    Goodarzi, Mohammad; Coelho, Leandro dos Santos; Honarparvar, Bahareh; Ortiz, Erlinda V; Duchowicz, Pablo R

    2016-06-01

    The application of molecular descriptors in describing Quantitative Structure Property Relationships (QSPR) for the estimation of vapor pressure (VP) of pesticides is of ongoing interest. In this study, QSPR models were developed using multiple linear regression (MLR) methods to predict the vapor pressure values of 162 pesticides. Several feature selection methods, namely the replacement method (RM), genetic algorithms (GA), stepwise regression (SR) and forward selection (FS), were used to select the most relevant molecular descriptors from a pool of variables. The optimum subset of molecular descriptors was used to build a QSPR model to estimate the vapor pressures of the selected pesticides. The Replacement Method improved the predictive ability of vapor pressures and was more reliable for the feature selection of these selected pesticides. The results provided satisfactory MLR models that had a satisfactory predictive ability, and will be important for predicting vapor pressure values for compounds with unknown values. This study may open new opportunities for designing and developing new pesticide.

  17. A METHOD FOR ESTIMATING GAS PRESSURE IN 3013 CONTAINERS USING AN ISP DATABASE QUERY

    Energy Technology Data Exchange (ETDEWEB)

    Friday, G; L. G. Peppers, L; D. K. Veirs, D

    2008-07-31

    The U.S. Department of Energy's Integrated Surveillance Program (ISP) is responsible for the storage and surveillance of plutonium-bearing material. During storage, plutonium-bearing material has the potential to generate hydrogen gas from the radiolysis of adsorbed water. The generation of hydrogen gas is a safety concern, especially when a container is breached within a glove box during destructive evaluation. To address this issue, the DOE established a standard (DOE, 2004) that sets the criteria for the stabilization and packaging of material for up to 50 years. The DOE has now packaged most of its excess plutonium for long-term storage in compliance with this standard. As part of this process, it is desirable to know within reasonable certainty the total maximum pressure of hydrogen and other gases within the 3013 container if safety issues and compliance with the DOE standards are to be attained. The principal goal of this investigation is to document the method and query used to estimate total (i.e. hydrogen and other gases) gas pressure within a 3013 container based on the material properties and estimated moisture content contained in the ISP database. Initial attempts to estimate hydrogen gas pressure in 3013 containers was based on G-values (hydrogen gas generation per energy input) derived from small scale samples. These maximum G-values were used to calculate worst case pressures based on container material weight, assay, wattage, moisture content, container age, and container volume. This paper documents a revised hydrogen pressure calculation that incorporates new surveillance results and includes a component for gases other than hydrogen. The calculation is produced by executing a query of the ISP database. An example of manual mathematical computations from the pressure equation is compared and evaluated with results from the query. Based on the destructive evaluation of 17 containers, the estimated mean absolute pressure was significantly

  18. Cardiac output assessment using oxygen consumption estimated from the left ventricular pressure-volume area.

    Science.gov (United States)

    Negroni, Jorge A; Lascano, Elena C; Bertolotti, Alejandro M; Gómez, Carmen B; Rodríguez Correa, Carlos A; Favaloro, Roberto R

    2010-01-01

    Use of a majority of structural variables (age, sex, height) to estimate oxygen consumption in the calculation of cardiac output (CO) by the Fick principle does not account for changes in physiological conditions. To improve this limitation, oxygen consumption was estimated based on the left ventricular pressure-volume area. A pilot study with 10 patients undergoing right cardiac catheterization showed that this approach was successful to estimate CO (r=0,73, vs. thermodilution measured CO). Further essays changing end-diastolic-volume in the pressure-volume area formula by body weight or body surface area showed that this last yielded the best correlation with the thermodilution measured CO (slope=1, ordinate =0.01 and r=0.93). These preliminary results indicate that use of a formula originated from the pressure-volume-area concept is a good alternative to estimate oxygen consumption for CO calculation.

  19. Surface stabilized GMR nanorods of silver coated CrO{sub 2} synthesized via a polymer complex at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, S., E-mail: drsomnathbiswas@gmail.com [The LNM Institute of Information Technology, Jaipur-302031 (India); Singh, G.P. [Centre for Nanotechnology, Central University of Jharkhand, Ranchi-835205 (India); Ram, S. [Materials Science Centre, Indian Institute of Technology, Kharagpur-721302 (India); Fecht, H.-J. [Insitut für Micro-und Nanomaterialien, Universität Ulm, Albert Einstein Allee-47, Ulm, D-89081, and Forschungszentrum Karlsruhe, Institute of Nanotechnology, Karlsruhe, D-76021 (Germany)

    2013-08-15

    Stable anisotropic nanorods of surface modified CrO{sub 2} (∼18 nm diameter) with a correlated diamagnetic layer (2–3 nm thickness) of silver efficiently tailors useful magnetic and magnetoresistance (MR) properties. Essentially, it involves a core-shell structure that is developed by displacing part of Cr{sup 4+} ions by Ag atoms on the CrO{sub 2} surface (topotactic surface layer) via an etching reaction of a CrO{sub 2}-polymer complex with Ag{sup +} ions in hot water followed by heating the dried sample at 300–400 °C in air. The stable Ag-layer so obtained in the form of a shell protects CrO{sub 2} such that it no longer converts to Cr{sub 2}O{sub 3} in ambient pressure during the processing. X-ray diffractogram of the Rutile type tetragonal CrO{sub 2} structure (lattice parameters a=0.4429 nm and c=0.2950 nm) includes weak peaks of a minority phase of an fcc-Ag (a=0.4086 nm). The silver surface layer, which manifests itself in a doublet of the 3d{sub 5/2} and 3d{sub 3/2} X-ray photoelectron bands of binding energies 368.46 eV and 374.48 eV, respectively, suppresses almost all Cr bands to appear in a measurable intensity. The sample exhibits a distinctly enhanced MR-value, e.g., (−) 7.6% at 77 K, than reported values in compacted CrO{sub 2} powders or composites. Such a large MR-value in the Coulomb blockade regime (<100 K) arises not only due to the suppressed spin flipping at low temperature but also from a spin dependent co-tunneling through an interlinked structure of silver and silver coated CrO{sub 2} nanorods. - Highlights: • Synthesis and structural studies of a novel GMR material of Ag coated CrO{sub 2}. • Tailoring useful GMR property in CrO{sub 2} nanorods of controlled shape and anisotropy. • Enhanced GMR is explained in correlation to the surface structure of CrO{sub 2} nanorods.

  20. Subharmonic aided pressure estimation for monitoring interstitial fluid pressure in tumours--in vitro and in vivo proof of concept.

    Science.gov (United States)

    Halldorsdottir, V G; Dave, J K; Eisenbrey, J R; Machado, P; Zhao, H; Liu, J B; Merton, D A; Forsberg, F

    2014-09-01

    The feasibility of using subharmonic aided pressure estimation (SHAPE) to noninvasively estimate interstitial fluid pressure (IFP) was studied. In vitro, radiofrequency signals, from 0.2 ml/l of Definity (Lantheus Medical Imaging, N Billerica, MA) were acquired within a water-tank with a Sonix RP ultrasound scanner (Analogic Ultrasound, Richmond, BC, Canada; fT/R=6.7/3.35 MHz and fT/R=10/5 MHz) and the subharmonic amplitudes of the signals were compared over 0-50 mmHg. In vivo, five swine with naturally occurring melanomas were studied. Subharmonic signals were acquired from tumours and surrounding tissue during infusion of Definity and compared to needle-based pressure measurements. Both in vitro and in vivo, an inverse linear relationship between hydrostatic pressure and subharmonic amplitude was observed with r(2)=0.63-0.95; p<0.05, maximum amplitude drop 11.36 dB at 10 MHz and -8 dB, and r(2) as high as 0.97; p<0.02 (10 MHz and -4/-8 dB most promising), respectively, indicating that SHAPE may be useful in monitoring IFP.

  1. Vapor pressures of the fluorinated telomer alcohols--limitations of estimation methods.

    Science.gov (United States)

    Stock, Naomi L; Ellis, David A; Deleebeeck, Lisa; Muir, Derek C G; Mabury, Scott A

    2004-03-15

    The influence of the unique, physical properties of poly- and perfluorinated chemicals on vapor pressure was investigated. Vapor pressures of a suite of fluorinated telomer alcohols (FTOHs) (CF3(CF2)nCH2CH2OH, where n = 3, 5, 7, or 9) were measured using the boiling point method and ranged from 144 to 992 Pa. Comparison of experimental and literature values indicate that perfluorocarbons (CF3(CF2)nCF3, where n = 0-6) and fluorinated telomer alcohols have vapor pressures equal to or greater than that of their hydrogen analogues. These chemically counterintuitive results can be explained by the unique geometry of poly- and perfluorinated chemicals--in particular the stiff, helical perfluorinated chain and the significant intramolecular hydrogen bonding of the FTOHs. The majority of models investigated for the estimation of vapor pressure did not compensate for this unique geometry and consistently underpredicted the vapor pressures of the FTOHs. Calculation of partitioning constants using both experimental and estimated vapor pressures indicate that both the Antoine and Modified Grain models, and to a lesser degree the Mackay model, are insufficiently accurate for estimating the vapor pressures of the FTOHs, particularly the longer chain FTOHs. Future models should consider parameters such as geometry, strength, and location of intramolecular hydrogen bonds and otherfunction groups in the molecule in order to improve vapor pressure estimation accuracy. It appears likely that the unique molecular geometry of the FTOHs influences not only their vapor pressure but also other physical properties and hence environmental fate and dissemination.

  2. A comparison of pulmonary arterial occlusion algorithms for estimation of pulmonary capillary pressure.

    Science.gov (United States)

    Pellett, A A; Johnson, R W; Morrison, G G; Champagne, M S; deBoisblanc, B P; Levitzky, M G

    1999-07-01

    Using the arterial occlusion method, we compared five literature-based estimates of pulmonary capillary pressure (Ppc) with the corresponding double occlusion pressures (Pdo) in anesthetized dogs whose chests had been closed after sternotomy for instrumentation. Arterial occlusions were performed with a balloon-tipped pulmonary artery catheter that housed pressure transducers immediately proximal and distal to the balloon. Separation of the proximal and distal pressure waveforms during balloon inflation allowed us to precisely define the moment of occlusion. We fit a monoexponential curve to pressure data beginning 200 ms after the onset of occlusion and a biexponential curve to data beginning at the instant of occlusion, with data obtained over a range of vascular states (control, serotonin infusion, histamine infusion). In addition, we investigated the use of sampling of the raw data to estimate capillary pressure. Three of the five literature-based estimates of Ppc yielded values similar to Pdo. The optimal (least average difference from Pdo) interpolation/extrapolation time points of the curve fits varied, depending on the type of curve fitting and the state of the pulmonary vasculature. We also determined that a close approximation of Pdo may be derived from the raw data, as an alternative to exponential curve fitting.

  3. Nanosecond Nd-YAG laser induced plasma emission characteristics in low pressure CO{sub 2} ambient gas for spectrochemical application on Mars

    Energy Technology Data Exchange (ETDEWEB)

    Lie, Zener Sukra; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia); Kagawa, Kiichiro [Fukui Science Education Academy, Takagi Chuou 2 choume, Fukui 910-0804 (Japan); Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia)

    2015-08-28

    An experimental study is conducted on the possibility and viability of performing spectrochemical analysis of carbon and other elements in trace amount in Mars, in particular, the clean detection of C, which is indispensible for tracking the sign of life in Mars. For this study, a nanosecond Nd-YAG laser is employed to generate plasma emission from a pure copper target in CO{sub 2} ambient gas of reduced pressure simulating the atmospheric condition of Mars. It is shown that the same shock wave excitation mechanism also works this case while exhibiting remarkably long cooling stage. The highest Cu emission intensities induced by 4 mJ laser ablation energy is attained in 600 Pa CO{sub 2} ambient gas. Meanwhile the considerably weaker carbon emission from the CO{sub 2} gas appears relatively featureless over the entire range of pressure variation, posing a serious problem for sensitive trace analysis of C contained in a solid sample. Our time resolved intensity measurement nevertheless reveals earlier appearance of C emission from the CO{sub 2} gas with a limited duration from 50 ns to 400 ns after the laser irradiation, well before the initial appearance of the long lasting C emission from the solid target at about 1 μs, due to the different C-releasing processes from their different host materials. The unwanted C emission from the ambient gas can thus be eliminated from the detected spectrum by a proper time gated detection window. The excellent spectra of carbon, aluminum, calcium, sodium, hydrogen, and oxygen obtained from an agate sample are presented to further demonstrate and verify merit of this special time gated LIBS using CO{sub 2} ambient gas and suggesting its viability for broad ranging in-situ applications in Mars.

  4. Estimation of cerebral vascular tone during exercise; evaluation by critical closing pressure in humans

    DEFF Research Database (Denmark)

    Ogoh, Shigehiko; Brothers, R Matthew; Jeschke, Monica;

    2010-01-01

    The aim of the present study was to calculate critical closing pressure (CCP) of the cerebral vasculature at rest and during exercise to estimate cerebral vascular tone. Five men and two women were seated upright for 15 min and then performed 15 min of right-legged knee extension exercise at 40, 60...... and 75% of their maximal workload (WL(max)). Middle cerebral artery blood velocity (MCA V) and blood pressure in the radial artery were recorded. The CCP was calculated by linear extrapolation from 1 min recordings of pairs of systolic and diastolic pressure and MCA V waveforms from both the right...

  5. Estimating seabed pressure from demersal trawls, seines, and dredges based on gear design and dimensions

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Breen, Mike;

    2016-01-01

    This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics......'s impact. An industry-based survey covering 13 countries provided the basis for estimating the relative impact-area contributions from individual gear components, whereas sediment penetration was estimated based on a literature review. For each gear group, a vessel size–gear size relationship was estimated...... to enable the prediction of gear footprint area and sediment penetration from vessel size. Application of these relationships with average vessel sizes and towing speeds provided hourly swept-area estimates by métier. Scottish seining has the largest overall gear footprint of ∼1.6 km2 h−1 of which 0.08 km2...

  6. Boosting the value of biodiesel byproduct by the non-catalytic transesterification of dimethyl carbonate via a continuous flow system under ambient pressure.

    Science.gov (United States)

    Kwon, Eilhann E; Yi, Haakrho; Jeon, Young Jae

    2014-10-01

    Transformation of coconut oil into biodiesel by using dimethyl carbonate (DMC) via a non-catalytic transesterification reaction under ambient pressure was investigated in this study. The non-catalytic transformation to biodiesel was achieved by means of a heterogeneous reaction between liquid triglycerides and gas phase DMC. The reaction was enhanced in the presence of porous material due to its intrinsic physical properties such as tortuosity and absorption/adsorption. The numerous pores in the material served as micro reaction chambers and ensured that there was enough contact time between the liquid triglycerides and the gaseous DMC, which enabled the completion of the transesterification. The highest fatty acid methyl esters (FAMEs) yield achieved was 98±0.5% within 1-2min at a temperature of 360-450°C under ambient pressure. The fast reaction rates made it possible to convert the lipid feedstock into biodiesel via a continuous flow system without the application of increased pressure. This suggested that the commonly used supercritical conditions could be avoided, resulting in huge cost benefits for biodiesel production. In addition, the high value of the byproduct from the transesterification of the lipid feedstock with DMC suggested that the production biodiesel using this method could be more economically competitive. Finally, the basic properties of biodiesel derived from the non-catalytic conversion of rapeseed oil with DMC were summarised.

  7. Novel method for estimating the dynamic characteristics of pressure sensor in shock tube calibration test.

    Science.gov (United States)

    Li, Qiang; Wang, Zhongyu; Wang, Zhuoran; Yan, Hu

    2015-06-01

    A shock tube is usually used to excite the dynamic characteristics of the pressure sensor used in an aircraft. This paper proposes a novel estimation method for determining the dynamic characteristic parameters of the pressure sensor. A preprocessing operation based on Grey Model [GM(1,1)] and bootstrap method (BM) is employed to analyze the output of a calibrated pressure sensor under step excitation. Three sequences, which include the estimated value sequence, upper boundary, and lower boundary, are obtained. The processing methods on filtering and modeling are used to explore the three sequences independently. The optimal estimated, upper boundary, and lower boundary models are then established. The three models are solved, and a group of dynamic characteristic parameters corresponding to the estimated intervals are obtained. A shock tube calibration test consisting of two experiments is performed to validate the performance of the proposed method. The results show that the relative errors of the dynamic characteristic parameters of time and frequency domains do not exceed 9% and 10%, respectively. Moreover, the nominal and estimated values of the parameters fall into the estimated intervals limited by the upper and lower values.

  8. Periodic density modulation for quasi-phase-matching of optical frequency conversion is inefficient under shallow focusing and constant ambient pressure.

    Science.gov (United States)

    Hadas, Itai; Bahabad, Alon

    2016-09-01

    The two main mechanisms of a periodic density modulation relevant to nonlinear optical conversion in a gas medium are spatial modulations of the index of refraction and of the number of emitters. For a one-dimensional model neglecting focusing and using a constant ambient pressure, it is shown theoretically and demonstrated numerically that the effects of these two mechanisms during frequency conversion cancel each other exactly. Under the considered conditions, this makes density modulation inefficient for quasi-phase-matching an optical frequency conversion process. This result is particularly relevant for high-order harmonic generation.

  9. Failure probability estimation of flaw in CANDU pressure tube considering the dimensional change

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Sang Log; Kim, Young Jin [Sungkyunkwan Univ., Suwon (Korea, Republic of); Lee, Joon Seong [Kyonggi Univ., Suwon (Korea, Republic of); Park, Youn Won [KINS, Taejon (Korea, Republic of)

    2002-11-01

    The pressure tube is a major component of the CANDU reactor, which supports nuclear fuel bundle and heavy water coolant. Pressure tubes are installed horizontally inside the reactor and only selected samples are periodically examined during in-service inspection. In this respect, a probabilistic safety assessment method is more appropriate for the assessment of overall pressure tube safety. The failure behavior of CANDU pressure tubes, however, is governed by delayed hydride cracking which is the major difference from pipings and reactor pressure vessels. Since the delayed hydride cracking has more widely distributed governing parameters, it is impossible to apply a general PFM methodology directly. In this paper, a PFM methodology for the safety assessment of CANDU pressure tubes is introduced by applying Monte Carlo simulation in determining failure probability. Initial hydrogen concentration, flaw shape and depth, axial and radial crack growth rate and fracture toughness were considered as probabilistic variables. Parametric study has been done under the base of pressure tube dimension and hydride precipitation temperature in calculating failure probability. Unstable fracture and plastic collapse are used for the failure assessment. The estimated failure probability showed about three-order difference with changing dimensions of pressure tube.

  10. Estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses

    Energy Technology Data Exchange (ETDEWEB)

    Cappa, F.; Guglielmi, Y.; Rutqvist, J.; Tsang, C.-F.; Thoraval, A.

    2008-03-16

    The flow parameters of a natural fracture were estimated by modeling in situ pressure pulses. The pulses were generated in two horizontal boreholes spaced 1 m apart vertically and intersecting a near-vertical highly permeable fracture located within a shallow fractured carbonate reservoir. Fracture hydromechanical response was monitored using specialized fiber-optic borehole equipment that could simultaneously measure fluid pressure and fracture displacements. Measurements indicated a significant time lag between the pressure peak at the injection point and the one at the second measuring point, located 1 m away. The pressure pulse dilated and contracted the fracture. Field data were analyzed through hydraulic and coupled hydromechanical simulations using different governing flow laws. In matching the time lag between the pressure peaks at the two measuring points, our hydraulic models indicated that (1) flow was channeled in the fracture, (2) the hydraulic conductivity tensor was highly anisotropic, and (3) the radius of pulse influence was asymmetric, in that the pulse travelled faster vertically than horizontally. Moreover, our parametric study demonstrated that the fluid pressure diffusion through the fracture was quite sensitive to the spacing and orientation of channels, hydraulic aperture, storativity and hydraulic conductivity. Comparison between hydraulic and hydromechanical models showed that the deformation significantly affected fracture permeability and storativity, and consequently, the fluid pressure propagation, suggesting that the simultaneous measurements of pressure and mechanical displacement signals could substantially improve the interpretation of pulse tests during reservoir characterization.

  11. Review of the Palisades pressure vessel accumulated fluence estimate and of the least squares methodology employed

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, P.J.

    1998-05-01

    This report provides a review of the Palisades submittal to the Nuclear Regulatory Commission requesting endorsement of their accumulated neutron fluence estimates based on a least squares adjustment methodology. This review highlights some minor issues in the applied methodology and provides some recommendations for future work. The overall conclusion is that the Palisades fluence estimation methodology provides a reasonable approach to a {open_quotes}best estimate{close_quotes} of the accumulated pressure vessel neutron fluence and is consistent with the state-of-the-art analysis as detailed in community consensus ASTM standards.

  12. Cryogenic liquid hydrogen storage for the civil aviation. Impacts of variable ambient pressures; Kryogene Fluessigwasserstoffspeicher fuer die zivile Luftfahrt. Auswirkungen variabler Umgebungsdruecke

    Energy Technology Data Exchange (ETDEWEB)

    Mock, Sebastian; Kabelac, Stephan [Helmut-Schmidt-Univ. / Univ. der Bundeswehr, Hamburg (Germany). Inst. fuer Thermodynamik

    2011-07-01

    If fuel cell systems are to be used as fuel in civilian aircraft, sufficient storage volumes must be available. Apart from safety and cost, low weight is one of the key requirements. The system weight of cryogenic liquid hydrogen stores depends, among others, on the pressures inside the store as these will directly affect the pressure vessel wall thickness. The liquid hydrogen store supplies the fuel cell with hydrogen at a defined pre-pressure. This is not the design-relevant maximum possible pressure, which is limited by relief and safety valves. The pressure levels in the system are composed of different fractions, e.g. pressure losses and pressure fluctuations in the system, as well as the safety factors for the safety valves. The maximum pressure should be kept as low as possible in order to minimize the system weight. The relief and safety valves are differential pressure valves that open at a defined pressure relative to ambient pressure. In aviation, there is the problem that the ambient pressure varies between about 1,02 bar(a) on the ground and 0.18 bar(a) in flight. If systems are designed as for ground applications, there is the problem that the required hydrogen pressure cannot be maintained in flight as the relief valves will open already at lower pressures. To prevent this, the permissible pressure levels and safety factor must be defined for in-flight applications. The contribution describes the proposed liquid hydrogen storage concept for in-flight applications and develops a definition for defining pressure levels and safety factors for cryogenic liquid hydrogen stores in aviation in consideration of the pertinent standards and technical rules. [German] Der Einsatz von Brennstoffzellensystemen in zivilen Flugzeugen erfordert nach derzeitigem Entwicklungsstand die Speicherung ausreichender Wasserstoffmengen an Bord, welcher dem System als Kraftstoff dient. Neben der Sicherheit und den Kosten ist ein geringes Gewicht eine der wichtigsten

  13. Spurious barometric pressure acceleration in Antarctica and propagation into GRACE Antarctic mass change estimates

    Science.gov (United States)

    Kim, Byeong-Hoon; Eom, Jooyoung; Seo, Ki-Weon; Wilson, Clark R.

    2016-08-01

    Apparent acceleration in Gravity Recovery and Climate Experiment (GRACE) Antarctic ice mass time-series may reflect both ice discharge and surface mass balance contributions. However, a recent study suggests there is also contamination from errors in atmospheric pressure de-aliasing fields [European Center for Medium-Range Weather Forecast (ECMWF) operational products] used during GRACE data processing. To further examine this question, we compare GRACE atmospheric pressure de-aliasing (GAA) fields with in situ surface pressure data from coastal and inland stations. Differences between the two are likely due to GAA errors, and provide a measure of error in GRACE solutions. Time-series of differences at individual weather stations are fit to four presumed error components: annual sinusoids, a linear trend, an acceleration term and jumps at times of known ECMWF model changes. Using data from inland stations, we estimate that atmospheric pressure error causes an acceleration error of about +7.0 Gt yr-2, which is large relative to prior GRACE estimates of Antarctic ice mass acceleration in the range of -12 to -14 Gt yr-2. We also estimate apparent acceleration rates from other barometric pressure (reanalysis) fields, including ERA-Interim, MERRA and NCEP/DOE. When integrated over East Antarctica, the four mass acceleration estimates (from GAA and the three reanalysis fields) vary considerably (by ˜2-16 Gt yr-2). This shows the need for further effort to improve atmospheric mass estimates in this region of sparse in situ observations, in order to use GRACE observations to measure ice mass acceleration and related sea level change.

  14. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-11-01

    Full Text Available The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure and compositions (argon, nitrogen and helium on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  15. Cost estimation of hypertension management based on home blood pressure monitoring alone or combined office and ambulatory blood pressure measurements.

    Science.gov (United States)

    Boubouchairopoulou, Nadia; Karpettas, Nikos; Athanasakis, Kostas; Kollias, Anastasios; Protogerou, Athanase D; Achimastos, Apostolos; Stergiou, George S

    2014-10-01

    This study aims at estimating the resources consumed and subsequent costs for hypertension management, using home blood pressure (BP) monitoring (HBPM) alone versus combined clinic measurements and ambulatory blood pressure monitoring (C/ABPM). One hundred sixteen untreated hypertensive subjects were randomized to use HBPM or C/ABPM for antihypertensive treatment initiation and titration. Health resources utilized within 12-months follow-up, their respective costs, and hypertension control were assessed. The total cost of the first year of hypertension management was lower in HBPM than C/ABPM arm (€1336.0 vs. €1473.5 per subject, respectively; P cost was identical in both arms. There was no difference in achieved BP control and drug expenditure (HBPM: €233.1 per subject; C/ABPM: €247.6 per subject; P = not significant), whereas the cost of BP measurements and/or visits was higher in C/ABPM arm (€393.9 vs. €516.9, per patient, respectively P cost for subsequent years (>1) was €348.9 and €440.2 per subject, respectively for HBPM and C/ABPM arm and €2731.4 versus €3234.3 per subject, respectively (P cost than C/ABPM, and the same trend is observed in 5-year projection. The results on the resources consumption can be used to make cost estimates for other health-care systems.

  16. Electronic properties and the nature of metal–insulator transition in NdNiO{sub 3} prepared at ambient oxygen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Hooda, M.K.; Yadav, C.S., E-mail: shkehar@iitmandi.ac.in

    2016-06-15

    We report the electronic properties of the NdNiO{sub 3}, prepared at the ambient oxygen pressure condition. The metal–insulator transition temperature is observed at 192 K, but the low temperature state is found to be less insulating compared to the NdNiO{sub 3} prepared at high oxygen pressure. The electric resistivity, Seebeck coefficient and thermal conductivity of the compound show large hysteresis below the metal–insulator transition. The large value of the effective mass (m*~8m{sub e}) in the metallic state indicates the narrow character of the 3d band. The electric conduction at low temperatures (T=2–20 K) is governed by the variable range hopping of the charge carriers.

  17. Electronic properties and the nature of metal-insulator transition in NdNiO3 prepared at ambient oxygen pressure

    Science.gov (United States)

    Hooda, M. K.; Yadav, C. S.

    2016-06-01

    We report the electronic properties of the NdNiO3, prepared at the ambient oxygen pressure condition. The metal-insulator transition temperature is observed at 192 K, but the low temperature state is found to be less insulating compared to the NdNiO3 prepared at high oxygen pressure. The electric resistivity, Seebeck coefficient and thermal conductivity of the compound show large hysteresis below the metal-insulator transition. The large value of the effective mass (m*~8me) in the metallic state indicates the narrow character of the 3d band. The electric conduction at low temperatures (T=2-20 K) is governed by the variable range hopping of the charge carriers.

  18. Estimating the state of charge of MH-Ni batteries by measuring their stable internal pressure

    Science.gov (United States)

    Zhang, Jian; Shao, Guangjie; Guo, Weiwen; Lou, Yuwan; Xia, Baojia

    2017-03-01

    Nickel metal hydride (MH-Ni) batteries are widely used in hybrid electric vehicles (HEVs). Estimating a battery's state of charge (SOC) remains challenging in practical applications, and it is also the core technology. Because MH-Ni batteries exhibit high rates of self-discharge and have flat and broad charge-discharge voltage plateaus, the estimation of their SOC through their voltage, current, internal resistance, and temperature is not accurate and has a large cumulative error. In this study, a new method for estimating SOC based on battery's stable internal pressure is proposed using the one-to-one correspondence between the hydrogen equilibrium pressure and the reversible hydrogen-storage capacity described by the pressure-concentration-isotherm (P-C-T) curves of hydrogen storage alloys. The actual SOC and the stable internal pressure of the battery have a one-to-one correspondence after the battery was stored at different temperatures and SOCs, and this relationship is maintained after different cycling number and after four years of storage.

  19. Particle tracking velocimetry applied to estimate the pressure field around a Savonius turbine

    Science.gov (United States)

    Murai, Yuichi; Nakada, Taishi; Suzuki, Takao; Yamamoto, Fujio

    2007-08-01

    Particle tracking velocimetry (PTV) is applied to flows around a Savonius turbine. The velocity vector field measured with PTV is utilized to estimate the pressure field around the turbine, as well as to evaluate the torque performance. The main objective of the work is the establishment of the pressure estimation scheme required to discuss the turbine performance. First, the PTV data are interpolated on a regular grid with a fourth-order ellipsoidal differential equation to generate velocity vectors satisfying the third-order spatio-temporal continuity both in time and space. Second, the phase-averaged velocity vector information with respect to the turbine angle is substituted into three different types of pressure-estimating equations, i.e. the Poisson equation, the Navier-Stokes equation and the sub-grid scale model of turbulence. The results obtained based on the Navier-Stokes equation are compared with those based on the Poisson equation, and have shown several merits in employing the Navier-Stokes-based method for the PTV measurement. The method is applied to a rotating turbine with the tip-speed ratio of 0.5 to find the relationship between torque behaviour and flow structure in a phase-averaged sense. We have found that a flow attached to the convex surface of the blades induces low-pressure regions to drive the turbine, namely, the lift force helps the turbine blades to rotate even when the drag force is insufficient. Secondary mechanisms of torque generation are also discussed.

  20. Non-invasive Estimation of Pressure Gradients in Pulsatile Flow using Ultrasound

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Villagómez Hoyos, Carlos Armando; Traberg, Marie Sand

    2014-01-01

    This paper investigates how pressure gradients in a pulsatile flow environment can be measured non-invasively using ultrasound. The presented set-up is based on vector velocity fields measured on a blood mimicking fluid moving at a peak flow rate of 1 ml/s through a constricted vessel. Fields...... and standard deviation of 10% and 13%, respectively, relative to peak estimated gradient. The paper concludes that maps of pressure gradients can be measured non-invasively using ultrasound with a precision of more than 85%...

  1. Estimating seabed pressure from demersal trawls, seines, and dredges based on gear design and dimensions

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Breen, Mike

    2016-01-01

    This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics...... such as logbook data. Here, we take a different approach starting from the gear itself (design and dimensions) to estimate the physical interactions with the seabed at the level of the individual fishing operation. We defined 14 distinct towed gear groups in European waters (eight otter trawl groups, three beam...

  2. Estimating source-attributable health impacts of ambient fine particulate matter exposure: global premature mortality from surface transportation emissions in 2005

    Science.gov (United States)

    Chambliss, S. E.; Silva, R.; West, J. J.; Zeinali, M.; Minjares, R.

    2014-10-01

    Exposure to ambient fine particular matter (PM2.5) was responsible for 3.2 million premature deaths in 2010 and is among the top ten leading risk factors for early death. Surface transportation is a significant global source of PM2.5 emissions and a target for new actions. The objective of this study is to estimate the global and national health burden of ambient PM2.5 exposure attributable to surface transportation emissions. This share of health burden is called the transportation attributable fraction (TAF), and is assumed equal to the proportional decrease in modeled ambient particulate matter concentrations when surface transportation emissions are removed. National population-weighted TAFs for 190 countries are modeled for 2005 using the MOZART-4 global chemical transport model. Changes in annual average concentration of PM2.5 at 0.5 × 0.67 degree horizontal resolution are based on a global emissions inventory and removal of all surface transportation emissions. Global population-weighted average TAF was 8.5 percent or 1.75 μg m-3 in 2005. Approximately 242 000 annual premature deaths were attributable to surface transportation emissions, dominated by China, the United States, the European Union and India. This application of TAF allows future Global Burden of Disease studies to estimate the sector-specific burden of ambient PM2.5 exposure. Additional research is needed to capture intraurban variations in emissions and exposure, and to broaden the range of health effects considered, including the effects of other pollutants.

  3. Pressure-induced Formation of Energetic and Structural Extended Solids with Quench-recovery to Ambient Conditions

    Science.gov (United States)

    2014-06-12

    carbon and SiO2 appear to reduce the polymerization pressure by a fraction of one GPa. The presence of metallic lithium and sodium appear to reduce the...Washington, Washington, DC (2012). 4) Strobel, T.A., Chemical Engineering Departmental Seminar, Colorado School of Mines , Golden, CO (2013). 5...polymerization pressure of CO was investigated in the presence of several different metal and non-metal catalysts. Metallic lithium and sodium, as well as non

  4. A study of the O/Ag(111) system with scanning tunneling microscopy and x-ray photoelectron spectroscopy at ambient pressures

    Science.gov (United States)

    Heine, Christian; Eren, Baran; Lechner, Barbara A. J.; Salmeron, Miquel

    2016-10-01

    The interaction of O2 with the Ag(111) surface was studied with scanning tunneling microscopy (STM) in the pressure range from 10- 9 Torr to 1 atm at room temperature and with X-ray photoelectron spectroscopy (XPS) up to 0.3 Torr O2 in the temperature range from RT to 413 K. STM images show that the Ag(111) surface topography is little affected in regions with large flat terraces, except for the appearance of mobile features due to oxygen atoms at pressures above 0.01 Torr. In regions where the step density is high, the surface became rough under 0.01 Torr of O2, due to the local oxidation of Ag. Various chemical states of oxygen due to chemisorbed, oxide and subsurface species were identified by XPS as a function of pressure and temperature. The findings from the STM images and XPS measurements indicate that formation of an oxide phase, the thermodynamically stable form at room temperature under ambient O2 pressure, is kinetically hindered in the flat terrace areas but proceeds readily in regions with high-step density.

  5. Preliminary investigation of an ultrasound method for estimating pressure changes in deep-positioned vessels

    Science.gov (United States)

    Olesen, Jacob Bjerring; Villagomez-Hoyos, Carlos Armando; Traberg, Marie Sand; Chee, Adrian J. Y.; Yiu, Billy Y. S.; Ho, Chung Kit; Yu, Alfred C. H.; Jensen, Jørgen Arendt

    2016-04-01

    This paper presents a method for measuring pressure changes in deep-tissue vessels using vector velocity ultrasound data. The large penetration depth is ensured by acquiring data using a low frequency phased array transducer. Vascular pressure changes are then calculated from 2-D angle-independent vector velocity fields using a model based on the Navier-Stokes equations. Experimental scans are performed on a fabricated flow phantom having a constriction of 36% at a depth of 100 mm. Scans are carried out using a phased array transducer connected to the experimental scanner, SARUS. 2-D fields of angle-independent vector velocities are acquired using directional synthetic aperture vector flow imaging. The obtained results are evaluated by comparison to a 3-D numerical simulation model with equivalent geometry as the designed phantom. The study showed pressure drops across the constricted phantom varying from -40 Pa to 15 Pa with a standard deviation of 32%, and a bias of 25% found relative to the peak simulated pressure drop. This preliminary study shows that pressure can be estimated non-invasively to a depth that enables cardiac scans, and thereby, the possibility of detecting the pressure drops across the mitral valve.

  6. Evaluation of Vapor Pressure Estimation Methods for Use in Simulating the Dynamic of Atmospheric Organic Aerosols

    Directory of Open Access Journals (Sweden)

    A. J. Komkoua Mbienda

    2013-01-01

    Lee and Kesler (LK, and Ambrose-Walton (AW methods for estimating vapor pressures ( are tested against experimental data for a set of volatile organic compounds (VOC. required to determine gas-particle partitioning of such organic compounds is used as a parameter for simulating the dynamic of atmospheric aerosols. Here, we use the structure-property relationships of VOC to estimate . The accuracy of each of the aforementioned methods is also assessed for each class of compounds (hydrocarbons, monofunctionalized, difunctionalized, and tri- and more functionalized volatile organic species. It is found that the best method for each VOC depends on its functionality.

  7. Sensitivity coefficients for the stochastic estimation of the radiation damage to the reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, C.M.; Hernandez Valle, S. [Centro de Investigaciones Tecnologicas, Nucleares y Ambientales, La Habana (Cuba). E-mail: calvarez@ctn.isctn.edu.cu; svalle@ctn.isctn.edu.cu

    2000-07-01

    The construction of the sensitivity matrix in the case of the vessel radiation damage estimation by Monte Carlo techniques poses new problems related to the uncertainties of the obtained responses. In the case of deterministic calculations, the sensitivity coefficient obtention is a straightforward procedure based on the perturbation formalism through the calculation of the adjoint fluxes. In the paper an alternative procedure implementation based on the differential operator method is described with the modifications needed to the used HEXANN-EVALU code for the response estimations in the VVER-440 pressure vessel. (author)

  8. Topological Pressure and Coding Sequence Density Estimation in the Human Genome

    CERN Document Server

    Koslicki, David

    2011-01-01

    Inspired by concepts from ergodic theory, we give new insight into coding sequence (CDS) density estimation for the human genome. Our approach is based on the introduction and study of topological pressure: a numerical quantity assigned to any finite sequence based on an appropriate notion of `weighted information content'. For human DNA sequences, each codon is assigned a suitable weight, and using a window size of approximately 60,000bp, we obtain a very strong positive correlation between CDS density and topological pressure. The weights are selected by an optimization procedure, and can be interpreted as quantitative data on the relative importance of different codons for the density estimation of coding sequences. This gives new insight into codon usage bias which is an important subject where long standing questions remain open. Inspired again by ergodic theory, we use the weightings on the codons to define a probability measure on finite sequences. We demonstrate that this measure is effective in disti...

  9. Effect of resting pressure on the estimate of cerebrospinal fluid outflow conductance

    Directory of Open Access Journals (Sweden)

    Andersson Kennet

    2011-03-01

    Full Text Available Abstract Background A lumbar infusion test is commonly used as a predictive test for patients with normal pressure hydrocephalus and for evaluation of cerebrospinal fluid (CSF shunt function. Different infusion protocols can be used to estimate the outflow conductance (Cout or its reciprocal the outflow resistance (Rout, with or without using the baseline resting pressure, Pr. Both from a basic physiological research and a clinical perspective, it is important to understand the limitations of the model on which infusion tests are based. By estimating Cout using two different analyses, with or without Pr, the limitations could be explored. The aim of this study was to compare the Cout estimates, and investigate what effect Prhad on the results. Methods Sixty-three patients that underwent a constant pressure infusion protocol as part of their preoperative evaluation for normal pressure hydrocephalus, were included (age 70.3 ± 10.8 years (mean ± SD. The analysis was performed without (Cexcl Pr and with (Cincl Pr Pr. The estimates were compared using Bland-Altman plots and paired sample t-tests (p Results Mean Cout for the 63 patients was: Cexcl Pr = 7.0 ± 4.0 (mean ± SD μl/(s kPa and Cincl Pr = 9.1 ± 4.3 μl/(s kPa and Rout was 19.0 ± 9.2 and 17.7 ± 11.3 mmHg/ml/min, respectively. There was a positive correlation between methods (r = 0.79, n = 63, p Cout= -2.1 ± 2.7 μl/(s kPa between methods was significant (p Rout was 1.2 ± 8.8 mmHg/ml/min. The Bland-Altman plot visualized that the variation around the mean difference was similar all through the range of measured values and there was no correlation between ΔCout and Cout. Conclusions The difference between Cout estimates, obtained from analyses with or without Pr, needs to be taken into consideration when comparing results from studies using different infusion test protocols. The study suggests variation in CSF formation rate, variation in venous pressure or a pressure dependent Cout

  10. Experimental Feasibility Study of Estimation of the Normalized Central Blood Pressure Waveform from Radial Photoplethysmogram

    Directory of Open Access Journals (Sweden)

    Edmond Zahedi

    2015-01-01

    Full Text Available The feasibility of a novel system to reliably estimate the normalized central blood pressure (CBPN from the radial photoplethysmogram (PPG is investigated. Right-wrist radial blood pressure and left-wrist PPG were simultaneously recorded in five different days. An industry-standard applanation tonometer was employed for recording radial blood pressure. The CBP waveform was amplitude-normalized to determine CBPN. A total of fifteen second-order autoregressive models with exogenous input were investigated using system identification techniques. Among these 15 models, the model producing the lowest coefficient of variation (CV of the fitness during the five days was selected as the reference model. Results show that the proposed model is able to faithfully reproduce CBPN (mean fitness = 85.2% ± 2.5% from the radial PPG for all 15 segments during the five recording days. The low CV value of 3.35% suggests a stable model valid for different recording days.

  11. Estimation of central aortic pressure waveform features derived from the brachial cuff volume displacement waveform.

    Science.gov (United States)

    Butlin, Mark; Qasem, Ahmad; Avolio, Alberto P

    2012-01-01

    There is increasing interest in non-invasive estimation of central aortic waveform parameters in the clinical setting. However, controversy has arisen around radial tonometric based systems due to the requirement of a trained operator or lack of ease of use, especially in the clinical environment. A recently developed device utilizes a novel algorithm for brachial cuff based assessment of aortic pressure values and waveform (SphygmoCor XCEL, AtCor Medical). The cuff was inflated to 10 mmHg below an individual's diastolic blood pressure and the brachial volume displacement waveform recorded. The aortic waveform was derived using proprietary digital signal processing and transfer function applied to the recorded waveform. The aortic waveform was also estimated using a validated technique (radial tonometry based assessment, SphygmoCor, AtCor Medical). Measurements were taken in triplicate with each device in 30 people (17 female) aged 22 to 79 years of age. An average for each device for each individual was calculated, and the results from the two devices were compared using regression and Bland-Altman analysis. A high correlation was found between the devices for measures of aortic systolic (R(2)=0.99) and diastolic (R(2)=0.98) pressure. Augmentation index and subendocardial viability ratio both had a between device R(2) value of 0.82. The difference between devices for measured aortic systolic pressure was 0.5±1.8 mmHg, and for augmentation index, 1.8±7.0%. The brachial cuff based approach, with an individualized sub-diastolic cuff pressure, provides an operator independent method of assessing not only systolic pressure, but also aortic waveform features, comparable to existing validated tonometric-based methods.

  12. Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

    Directory of Open Access Journals (Sweden)

    J. H. Seinfeld

    2011-03-01

    Full Text Available The sensitivity of the formation of secondary organic aerosol (SOA to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A. Vapour pressures (Pvap were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation, differences in the predicted Pvap range between a factor of 5 to 200 in average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

  13. Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

    Directory of Open Access Journals (Sweden)

    R. Valorso

    2011-07-01

    Full Text Available The sensitivity of the formation of secondary organic aerosol (SOA to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A. Vapour pressures (Pvap were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation, differences in the predicted Pvap range between a factor of 5 to 200 on average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

  14. Experimental study of void space, permeability and elastic anisotropy in crustal rocks under ambient and hydrostatic pressure

    Science.gov (United States)

    Benson, Philip Michael

    Anisotropy in the physical and transport properties of crustal rocks is a key influence on crustal evolution and energy resource management. Data from deep seismic soundings, borehole logging and laboratory measurement all show that the physical properties of the earth are anisotropic. Such anisotropy generally results from the superposition of fabric development during diagenesis and/or petrogenesis, and the application of anisotropic tectonic stresses. This leads to an aligned crack and pore fabric in crustal rocks that, in turn, leads to seismic velocity anisotropy and permeability anisotropy. This thesis describes an experimental study which aims to investigate the relationships between pressure, pore fabric geometry and seismic and permeability anisotropy under hydrostatic pressures from room pressure to ~4km depth equivalence within the Earth's crust. Firstly, pore fabric analyses of three representative crustal rock types is presented. These rock types represent a range of crack and pore fabrics. The average void space shape and orientation is determined 3-D using the methods of anisotropy of magnetic susceptibility and velocity anisotropy. Scanning electron microscopy and fluorescent-dye crack imaging techniques further aid in the void space characterisation. Secondly, the development and application of an apparatus capable of contemporaneously measuring elastic wave velocity, porosity and permeability at effective pressures of up to 100 MPa is described. Results are analysed in terms of applied effective pressure and the rock pore fabric type and orientation. Finally, the laboratory data are used to test models that attempt to predict geophysical parameters such as permeability and elastic wave velocity from microstructural attributes. This multi-facetted analysis allows a number of conclusions to be drawn, expanding the state-of-the-art in how the pore fabric microstructure of crustal rock is represented by the methods of elastic wave velocity and

  15. On the implementation of an automated acoustic output optimization algorithm for subharmonic aided pressure estimation.

    Science.gov (United States)

    Dave, J K; Halldorsdottir, V G; Eisenbrey, J R; Merton, D A; Liu, J B; Machado, P; Zhao, H; Park, S; Dianis, S; Chalek, C L; Thomenius, K E; Brown, D B; Forsberg, F

    2013-04-01

    Incident acoustic output (IAO) dependent subharmonic signal amplitudes from ultrasound contrast agents can be categorized into occurrence, growth or saturation stages. Subharmonic aided pressure estimation (SHAPE) is a technique that utilizes growth stage subharmonic signal amplitudes for hydrostatic pressure estimation. In this study, we developed an automated IAO optimization algorithm to identify the IAO level eliciting growth stage subharmonic signals and also studied the effect of pulse length on SHAPE. This approach may help eliminate the problems of acquiring and analyzing the data offline at all IAO levels as was done in previous studies and thus, pave the way for real-time clinical pressure monitoring applications. The IAO optimization algorithm was implemented on a Logiq 9 (GE Healthcare, Milwaukee, WI) scanner interfaced with a computer. The optimization algorithm stepped the ultrasound scanner from 0% to 100% IAO. A logistic equation fitting function was applied with the criterion of minimum least squared error between the fitted subharmonic amplitudes and the measured subharmonic amplitudes as a function of the IAO levels and the optimum IAO level was chosen corresponding to the inflection point calculated from the fitted data. The efficacy of the optimum IAO level was investigated for in vivo SHAPE to monitor portal vein (PV) pressures in 5 canines and was compared with the performance of IAO levels, below and above the optimum IAO level, for 4, 8 and 16 transmit cycles. The canines received a continuous infusion of Sonazoid microbubbles (1.5 μl/kg/min; GE Healthcare, Oslo, Norway). PV pressures were obtained using a surgically introduced pressure catheter (Millar Instruments, Inc., Houston, TX) and were recorded before and after increasing PV pressures. The experiments showed that optimum IAO levels for SHAPE in the canines ranged from 6% to 40%. The best correlation between changes in PV pressures and in subharmonic amplitudes (r=-0.76; p=0

  16. Estimation of the Effect of Pressure on the Equilibrium of the TRIS Buffer System

    Science.gov (United States)

    Rodriguez, C.; Huang, F.; Millero, F. J., Jr.

    2014-12-01

    Recently, autonomous sensors have been developed to profile the in-situ chemistry of a water column. These sensors provide extensive, long-term data of ocean chemistry, contributing to our understanding of the state of oceanic pH and overall trends in acidification. Measurements obtained from these sensors should account for the effects of in-situ physical parameters on the chemical equilibria of the system. TRIS-HCl buffers are frequently used in calibration of pH measuring systems. The effects of temperature and salinity on its dissociation constant (K) at 1atm pressure are understood; however, the effects of higher pressures are yet uncharacterized. The effect of pressure on the thermodynamic equilibrium constant can be represented by KP/K0, where the superscript P denotes gauge pressure and 0 denotes atmospheric pressure. For weak acids, this can be estimated from data of the partial molal volumes (v0) and compressibilities (k0) measured at 1atm. We have measured the density and sound speed of TRIS and TRIS-HCl to determine values for v0 and k0 in water, NaCl, and seawater as a function of temperature. Results show that the partial molal properties are higher in NaCl than in water and increase with temperature. This is attributed to changes in solute-solvent interactions and solute-hydration. The values in seawater and NaCl of equal ionic strength are in reasonable agreement, supporting the use of NaCl as a medium representative of seawater. The results are used to estimate the effect of pressure on the dissociation of TRIS-HCl up to 1000 bars. The effect of pressure is found to be greater in water than in NaCl or seawater, and decreases with temperature. The largest effect is seen in water at 5oC (K1000 = 1.044 K0). While this deviation may appear to be minor, it offsets the pK(TRIS-HCl) by 0.02 units, well within the reporting limits. Thus, the effect of pressure becomes more important in freshwater systems with low in-situ temperatures. These new equations

  17. Clinical usefulness of the second peak of radial systolic blood pressure for estimation of aortic systolic blood pressure.

    Science.gov (United States)

    Kohara, K; Tabara, Y; Tomita, H; Nagai, T; Igase, M; Miki, T

    2009-08-01

    Central aortic blood pressure (BP), obtained from radial arterial waveform using the transfer function method (TFM), has been shown to have prognostic value independently of brachial BP. In this study, the relationship between peripheral systolic BP (SBP) and aortic SBP was evaluated. We further investigated whether TFM-derived aortic SBP can be estimated by information obtained from the radial waveform. The radial waveform was analysed to obtain the first peak of radial SBP (SBP1), second peak of radial SBP (SBP2), radial augmentation index (AI) (radial (SBP2-DBP)/(SBP1-DBP) x 100 and aortic SBP and AI using TFM in 233 subjects in the supine position. Measurements were repeated after changing position to the prone position. The constructed equation was validated in 149 community residents with different backgrounds. Radial SBP2 was closer to TFM-derived aortic SBP compared with brachial SBP. TFM-derived aortic SBP was approximated by the equation: aortic SBP=18.9-radial SBP2-0.03 x HR-0.214 x radial AI (r2=0.992). The equation was also applicable to predicting aortic SBP in the prone position as well as in different populations (mean difference between predicted aortic SBP and TFM-derived aortic SBP: -0.01+/-1.34 and 1.05+/-1.47 mm Hg, respectively). Radial arterial waveform analysis can be used for estimation of TFM-derived aortic SBP.

  18. Air Pollution and Preterm Birth in the U.S. State of Georgia (2002–2006): Associations with Concentrations of 11 Ambient Air Pollutants Estimated by Combining Community Multiscale Air Quality Model (CMAQ) Simulations with Stationary Monitor Measurements

    Science.gov (United States)

    Hao, Hua; Chang, Howard H.; Holmes, Heather A.; Mulholland, James A.; Klein, Mitch; Darrow, Lyndsey A.; Strickland, Matthew J.

    2015-01-01

    Background: Previous epidemiologic studies suggest associations between preterm birth and ambient air pollution. Objective: We investigated associations between 11 ambient air pollutants, estimated by combining Community Multiscale Air Quality model (CMAQ) simulations with measurements from stationary monitors, and risk of preterm birth (Darrow LA, Strickland MJ. 2016. Air pollution and preterm birth in the U.S. state of Georgia (2002–2006): associations with concentrations of 11 ambient air pollutants estimated by combining Community Multiscale Air Quality Model (CMAQ) simulations with stationary monitor measurements. Environ Health Perspect 124:875–880; http://dx.doi.org/10.1289/ehp.1409651 PMID:26485731

  19. Estimation of foot pressure from human footprint depths using 3D scanner

    Science.gov (United States)

    Wibowo, Dwi Basuki; Haryadi, Gunawan Dwi; Priambodo, Agus

    2016-03-01

    The analysis of normal and pathological variation in human foot morphology is central to several biomedical disciplines, including orthopedics, orthotic design, sports sciences, and physical anthropology, and it is also important for efficient footwear design. A classic and frequently used approach to study foot morphology is analysis of the footprint shape and footprint depth. Footprints are relatively easy to produce and to measure, and they can be preserved naturally in different soils. In this study, we need to correlate footprint depth with corresponding foot pressure of individual using 3D scanner. Several approaches are used for modeling and estimating footprint depths and foot pressures. The deepest footprint point is calculated from z max coordinate-z min coordinate and the average of foot pressure is calculated from GRF divided to foot area contact and identical with the average of footprint depth. Evaluation of footprint depth was found from importing 3D scanner file (dxf) in AutoCAD, the z-coordinates than sorted from the highest to the lowest value using Microsoft Excel to make footprinting depth in difference color. This research is only qualitatif study because doesn't use foot pressure device as comparator, and resulting the maximum pressure on calceneus is 3.02 N/cm2, lateral arch is 3.66 N/cm2, and metatarsal and hallux is 3.68 N/cm2.

  20. Estimation of Coefficient of Pressure in High Rise Buildings Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    S. K. Verma

    2014-04-01

    Full Text Available Tendency to build more slender and more flexible tall buildings have made these structures susceptible to action of wind. Therefore, wind force is one of the prime considerations in design of tall buildings. The prediction of wind-induced pressure coefficients on the surface of the buildings is of considerable practical importance. Wind tunnel testing is one of the main methods for wind load determination on structures. But this being, time consuming and costly wind tunnel tests can only cover a limited number of cases. The present work focuses on the application of artificial neural networks (ANNs to estimate pressure coefficients on surface of tall buildings. In the present study, two cases of training data set (consisting of geometrical coordinates of pressure points and angle at which wind strikes at the face of the building as the input to the network has been used to predict the wind- induced `pressure coefficients Cp (mean (output of the network for the previously any wind incident angle. The performance of the network is assessed in terms of Root Mean Square Error (RMSE and Correlation Coefficient R. From the present study, it is concluded that the value of Cp (Mean goes on decreasing with increase in Wind Incidence Angle for the same pressure point. Also, suction effect is noticed near the corners of the building.

  1. Effect of H2S and COS in the fuel gas on the performance of ambient pressure phosphoric acid fuel cells

    Science.gov (United States)

    Ross, P. N., Jr.

    1985-04-01

    The objective of this project was to determine in laboratory cells the tolerance of phosphoric acid fuel cells (PAFC) to hydrogen sulfide and carbonyl sulphide impurities in the anode feed gas. The study was conducted in three phases: the first was testing in a small (1 sq cm) free electrolyte cell to examine the effect of electrode structure on cell tolerance and to determine the order of magnitude of sulfur causing failure in cells at zero utilization; the second was testing in standard 2' x 2' PAFC laboratory hardware at ambient pressure to examine the effect of hydrogen utilization on tolerance and the possible effect of fuel impurities on cathode performance; the final phase was testing with a 2' x 2' cell in a pressure vessel to determine the effect of pressurized operation on cell tolerance. The poisoning effect of hydrogen sulfide was characteristically different from the effects of carbon monoxide, in that it was not manifested by a marginal (e.g., 0 to 50 mV) increase in anode potential but either had no effect or caused catastrophic polarization. Critical levels were derived for hydrogen sulfide as related to cell operating conditions.

  2. Comparison of dielectric barrier discharge, atmospheric pressure radiofrequency-driven glow discharge and direct analysis in real time sources for ambient mass spectrometry of acetaminophen

    Energy Technology Data Exchange (ETDEWEB)

    Kratzer, Jan [Institute for National Measurement Standards, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Institute of Analytical Chemistry of the ASCR, v.v.i., Veveri 97, CZ-602 00 Brno (Czech Republic); Mester, Zoltan [Institute for National Measurement Standards, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Sturgeon, Ralph E., E-mail: Ralph.Sturgeon@nrc-cnrc.gc.ca [Institute for National Measurement Standards, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada)

    2011-08-15

    Three plasma-based ambient pressure ion sources were investigated; laboratory constructed dielectric barrier and rf glow discharges, as well as a commercial corona discharge (DART source). All were used to desorb and ionize a model analyte, providing sampling techniques for ambient mass spectrometry (MS). Experimental parameters were optimized to achive highest signal for acetaminophen as the analyte. Insight into the mechanisms of analyte desorption and ionization was obtained by means of emission spectrometry and ion current measurements. Desorption and ionization mechanisms for this analyte appear to be identical for all three plasma sources. Emission spectra differ only in the intensities of various lines and bands. Desorption of solid analyte requires transfer of thermal energy from the plasma source to sample surface, in the absence of which complete loss of MS response occurs. For acetaminophen, helium was the best plasma gas, providing 100- to 1000-fold higher analyte response than with argon or nitrogen. The same trend was also evident with background ions (protonated water clusters). MS analyte signal intensity correlates with the ion density (expressed as ion current) in the plasma plume and with emission intensity from excited state species in the plasma. These observations support an ionization process which occurs via proton transfer from protonated water clusters to analyte molecules.

  3. Quantitative estimates of reaction induced pressures: an example from the Norwegian Caledonides.

    Science.gov (United States)

    Vrijmoed, Johannes C.; Podladchikov, Yuri Y.

    2013-04-01

    Estimating the pressure and temperature of metamorphic rocks is fundamental to the understanding of geodynamics. It is therefore important to determine the mechanisms that were responsible for the pressure and temperature obtained from metamorphic rocks. Both pressure and temperature increase with depth in the Earth. Whereas temperature can vary due to local heat sources such as magmatic intrusions, percolation of hot fluids or deformation in shear zones, pressure in petrology is generally assumed to vary homogeneously with depth. However, fluid injection into veins, development of pressure shadows around porphyroblasts, fracturing and folding of rocks all involve variations in stress and therefore also in pressure (mean stress). Volume change during phase transformations or mineral reactions have the potential to build pressure if they proceed faster than the minerals or rocks can deform to accommodate the volume change. This mechanism of pressure generation does not require the rocks to be under differential stress, it may lead however to the development of local differential stress. The Western Gneiss Region (WGR) is a basement window within the Norwegian Caledonides. This area is well known for its occurrences of HP to UHP rocks, mainly found as eclogite boudins and lenses and more rarely within felsic gneisses. Present observations document a regional metamorphic gradient increasing towards the NW, and structures in the field can account for the exhumation of the (U)HP rocks from ~2.5 to 3 GPa. Locally however, mineralogical and geothermobarometric evidence points to metamorphic pressure up to 4 GPa. These locations present an example of local extreme pressure excursions from the regional and mostly coherent metamorphic gradient that are difficult to account for by present day structural field observations. Detailed structural, petrological, mineralogical, geochemical and geochronological study at the Svartberget UHP diamond locality have shown the injection

  4. Online Estimation of Model Parameters and State of Charge of LiFePO4 Batteries Using a Novel Open-Circuit Voltage at Various Ambient Temperatures

    Directory of Open Access Journals (Sweden)

    Fei Feng

    2015-04-01

    Full Text Available This study describes an online estimation of the model parameters and state of charge (SOC of lithium iron phosphate batteries in electric vehicles. A widely used SOC estimator is based on the dynamic battery model with predeterminate parameters. However, model parameter variances that follow with their varied operation temperatures can result in errors in estimating battery SOC. To address this problem, a battery online parameter estimator is presented based on an equivalent circuit model using an adaptive joint extended Kalman filter algorithm. Simulations based on actual data are established to verify accuracy and stability in the regression of model parameters. Experiments are also performed to prove that the proposed estimator exhibits good reliability and adaptability under different loading profiles with various temperatures. In addition, open-circuit voltage (OCV is used to estimate SOC in the proposed algorithm. However, the OCV based on the proposed online identification includes a part of concentration polarization and hysteresis, which is defined as parametric identification-based OCV (OCVPI. Considering the temperature factor, a novel OCV–SOC relationship map is established by using OCVPI under various temperatures. Finally, a validating experiment is conducted based on the consecutive loading profiles. Results indicate that our method is effective and adaptable when a battery operates at different ambient temperatures.

  5. Full-Scale Testing of the Ambient Pressure, Acid-Dissolution Front-End Process for the Current 99Mo Recovery Processes

    Energy Technology Data Exchange (ETDEWEB)

    Jerden, James L. [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Science and Engineering Division; Bailey, James [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Science and Engineering Division; Hafenrichter, Lohman [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Science and Engineering Division; Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Science and Engineering Division

    2013-01-31

    The Global Threat Reduction Initiative (GTRI) Conversion Program is actively developing technologies for converting civilian facilities that use high enriched uranium (HEU) to low enriched uranium (LEU) fuels and targets. The conversion of conventional HEU targets to LEU for the production of 99Mo production requires approximately five times the uranium in a target to maintain the 99Mo yield on a per-target basis. Under GTRI, Argonne National Laboratory (Argonne) is developing two frontend options for current 99Mo production processes to allow the use of LEU-foil targets. In both processes, the aim is to produce a frontend product that is compatible with current 99Mo purification operations and will provide the same or a higher yield of 99Mo for the same number of irradiated targets. The two frontend processes under development as part of this project are (1) the dissolution of irradiated LEU foil (up to 250 g in a single batch) and nickel fission recoil barrier in nitric acid at ambient pressure; and (2) the electrochemical dissolution of LEU foil in series of steps that produces an alkaline (basic) solution feed for 99Mo purification. This report describes results from performance tests and design optimization of the ambient pressure, nitric-acid-dissolver system. The design, fabrication, and performance test planning for this system are described in more detail in previous reports (Jerden et al. 2011a,b, 2012). Full-scale demonstrations of both of the frontend processes using irradiated uranium foils are planned to be performed at Oak Ridge National Laboratory this fiscal year.

  6. [The improvement of the Doppler echocardiographic method for the estimation of pulmonary systolic pressure].

    Science.gov (United States)

    Tamborini, G; Pepi, M; Galli, C; Alimento, M; Barbier, P; Doria, E; Maltagliati, A; Berti, M; Fiorentini, C; Guazzi, M D

    1993-04-01

    The formulas currently utilized for noninvasive evaluation of right ventricular systolic pressure (RVSP) include right ventricular-right atrial pressure gradient (RV-RAG) and right atrial pressure (RAP). The former is expressed by trans-tricuspid systolic flow velocity, the latter is generally assumed. We recently observed that ultrasound estimation of RAP through inferior vena cava collapsibility index (CI) may help in the choice of the more appropriate formula for the evaluation of RVSP. However, these traditional methods (method A:RV-RAG + 10; method B:RV-RAG x 1.1 + 14) have limitations, particularly when RAP is low. The present study was undertaken to improve noninvasive estimation of RVSP through new formulas based on CI prediction of RAP. One hundred and four patients, in whom tricuspid regurgitation was adequately documented with CW-Doppler, were included in this study. They were classified into 3 groups: Group 1 with CI > 45%, Group 2 with CI < or = 35%, Group 3 with CI 35-45%. RVSP was evaluated by 3 different methods: A, B, and C. Method C was based on CI, assigning 6, 16, or 9 mmHg to RAP (respectively, the mean values in the 3 groups of our previous study). Results indicate that method C improves noninvasive estimation of RVSP in Group 1 and Group 2, with respect to other methods, with reduction of the SEE and of the mean difference of the t-test between hemodynamic and echographic values. In Group 3, Doppler estimation by method A and C, and catheter measurements are comparable, whereas method B significantly overestimates the actual value.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Investigating half-metallicity in PtXSb alloys (X=V, Mn, Cr, Co) at ambient and high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Habbak, Enas L., E-mail: enas_habbak@yahoo.com [Department of Physics, Faculty of Science, Damietta University (Egypt); Shabara, Reham M., E-mail: rehamph@hotmail.com [Department of Physics, Faculty of Science, Damietta University (Egypt); Aly, Samy H., E-mail: samy.ha.aly@gmail.com [Department of Physics, Faculty of Science, Damietta University (Egypt); Yehia, Sherif, E-mail: sherif542002@yahoo.com [Department of Physics, Faculty of Science, Helwan University, Cairo (Egypt)

    2016-08-01

    The structural, electronic, magnetic and elastic properties of half-Heusler alloys PtMnSb, PtVSb, PtCrSb and PtCoSb are investigated using first-principles calculation based on Density Functional Theory DFT. The Full Potential local Orbital (FPLO) method, within the General Gradient Approximation (GGA) and Local Spin Density Approximation (LSDA), have been used. The calculated structural, electronic and magnetic properties are in good agreement with available experimental and theoretical data. Using GGA approximation, only PtVSb shows a half-metallic behavior with a spin-down band gap and total magnetic moment of 0.802 eV and 2 µ{sub B} respectively. Both of PtVSb and PtMnSb alloys are half-metallic with spin-down band gaps of 0.925 eV and 0.832 eV and magnetic moments of 2 µ{sub B} and 4 µ{sub B} respectively using LSDA approximation. The bulk modulus and its first pressure-derivative of these alloys are calculated using the modified Birch–Murnaghan equation of state (EOS). The effect of pressure on the lattice constant, energy gap and bulk modulus is investigated. Under pressure, PtMnSb and PtCrSb turn into half-metallic alloys at nearly 6 GPa and 27 GPa respectively using GGA approximation.

  8. Investigating half-metallicity in PtXSb alloys (X=V, Mn, Cr, Co) at ambient and high pressure

    Science.gov (United States)

    Habbak, Enas L.; Shabara, Reham M.; Aly, Samy H.; Yehia, Sherif

    2016-08-01

    The structural, electronic, magnetic and elastic properties of half-Heusler alloys PtMnSb, PtVSb, PtCrSb and PtCoSb are investigated using first-principles calculation based on Density Functional Theory DFT. The Full Potential local Orbital (FPLO) method, within the General Gradient Approximation (GGA) and Local Spin Density Approximation (LSDA), have been used. The calculated structural, electronic and magnetic properties are in good agreement with available experimental and theoretical data. Using GGA approximation, only PtVSb shows a half-metallic behavior with a spin-down band gap and total magnetic moment of 0.802 eV and 2 μB respectively. Both of PtVSb and PtMnSb alloys are half-metallic with spin-down band gaps of 0.925 eV and 0.832 eV and magnetic moments of 2 μB and 4 μB respectively using LSDA approximation. The bulk modulus and its first pressure-derivative of these alloys are calculated using the modified Birch-Murnaghan equation of state (EOS). The effect of pressure on the lattice constant, energy gap and bulk modulus is investigated. Under pressure, PtMnSb and PtCrSb turn into half-metallic alloys at nearly 6 GPa and 27 GPa respectively using GGA approximation.

  9. A theoretical study of MgH2 ambient and high-pressure phases using NQCC parameters

    Science.gov (United States)

    Rafiee, Marjan A.

    2014-12-01

    Quadrupolar parameters of nuclei can be used as a tool to understand the electronic structure of the compounds. Magnesium hydride (MgH2) is a potential hydrogen storage material due to its outstanding hydrogen capacity, however, its high thermodynamic stability is unfavorable for dehydrogenation processes. Understanding the bonding nature of Mg and H is essential for improving its dehydrogenation performance. In this work the charge density distribution in MgH2 is studied. For this purpose, using calculated NQCCs of hydrogen atoms, the electronic structure of α-MgH2 with several high pressure forms of MgH2 were compared. The results show that in the high pressure phases (β, γ, and δ) some hydrogens have very small NQCC and therefore these hydrogens form weaker bond with Mg. In other words, easier condition for dehydrogenation in pressure-induced forms is expected. The electric field gradient (EFG) at the site of quadrupolar nuclei were calculated to obtain NQCC parameters using Gaussian 03 at B3LYP/6-31G level of theory. The selected level and basis set give the rather acceptable qualitative NQCCs of hydrogen atoms.

  10. Transportation-cyber-physical-systems-oriented engine cylinder pressure estimation using high gain observer

    Science.gov (United States)

    Li, Yong-Fu; Xiao-Pei, Kou; Zheng, Tai-Xiong; Li, Yin-Guo

    2015-05-01

    In transportation cyber-physical-systems (T-CPS), vehicle-to-vehicle (V2V) communications play an important role in the coordination between individual vehicles as well as between vehicles and the roadside infrastructures, and engine cylinder pressure is significant for engine diagnosis on-line and torque control within the information exchange process under V2V communications. However, the parametric uncertainties caused from measurement noise in T-CPS lead to the dynamic performance deterioration of the engine cylinder pressure estimation. Considering the high accuracy requirement under V2V communications, a high gain observer based on the engine dynamic model is designed to improve the accuracy of pressure estimation. Then, the analyses about convergence, converge speed and stability of the corresponding error model are conducted using the Laplace and Lyapunov method. Finally, results from combination of Simulink with GT-Power based numerical experiments and comparisons demonstrate the effectiveness of the proposed approach with respect to robustness and accuracy. Project supported by the National Natural Science Foundation of China (Grant No. 61304197), the Scientific and Technological Talents of Chongqing, China (Grant No. cstc2014kjrc-qnrc30002), the Key Project of Application and Development of Chongqing, China (Grant No. cstc2014yykfB40001), the Natural Science Funds of Chongqing, China (Grant No. cstc2014jcyjA60003), and the Doctoral Start-up Funds of Chongqing University of Posts and Telecommunications, China (Grant No. A2012-26).

  11. Modelled in vivo HIV fitness under drug selective pressure and estimated genetic barrier towards resistance are predictive for virological response

    DEFF Research Database (Denmark)

    Deforche, Koen; Cozzi-Lepri, Alessandro; Theys, Kristof

    2008-01-01

    BACKGROUND: A method has been developed to estimate a fitness landscape experienced by HIV-1 under treatment selective pressure as a function of the genotypic sequence thereby also estimating the genetic barrier to resistance. METHODS: We evaluated the performance of two estimated fitness landsca...

  12. Automated midline shift and intracranial pressure estimation based on brain CT images.

    Science.gov (United States)

    Chen, Wenan; Belle, Ashwin; Cockrell, Charles; Ward, Kevin R; Najarian, Kayvan

    2013-04-13

    In this paper we present an automated system based mainly on the computed tomography (CT) images consisting of two main components: the midline shift estimation and intracranial pressure (ICP) pre-screening system. To estimate the midline shift, first an estimation of the ideal midline is performed based on the symmetry of the skull and anatomical features in the brain CT scan. Then, segmentation of the ventricles from the CT scan is performed and used as a guide for the identification of the actual midline through shape matching. These processes mimic the measuring process by physicians and have shown promising results in the evaluation. In the second component, more features are extracted related to ICP, such as the texture information, blood amount from CT scans and other recorded features, such as age, injury severity score to estimate the ICP are also incorporated. Machine learning techniques including feature selection and classification, such as Support Vector Machines (SVMs), are employed to build the prediction model using RapidMiner. The evaluation of the prediction shows potential usefulness of the model. The estimated ideal midline shift and predicted ICP levels may be used as a fast pre-screening step for physicians to make decisions, so as to recommend for or against invasive ICP monitoring.

  13. Ambient Dried Aerogels

    Science.gov (United States)

    Jones, Steven M.; Paik, Jong-Ah

    2013-01-01

    A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

  14. Influência da temperatura na solubilidade de beta-caroteno em solventes orgânicos à pressão ambiente Effect of temperature on the solubility of beta-carotene in organic solvents under ambient pressure

    Directory of Open Access Journals (Sweden)

    Marcus Vinícius Três

    2007-12-01

    Full Text Available O presente trabalho reporta dados experimentais de solubilidade em pressão ambiente de beta-caroteno em solventes orgânicos puros (etanol, acetona, acetato de etila e diclorometano e em misturas de tais solventes no intervalo de temperatura de 10 a 60 °C. Para este fim, adotou-se o método gravimétrico para a determinação da solubilidade, utilizando células encamisadas de equilíbrio. Os resultados mostraram que valores mais elevados de solubilidade são obtidos quando foram empregados solventes com parâmetros de solubilidade mais próximos daquele do soluto. Verificou-se que o aumento da temperatura, tanto para solventes puros, como para as misturas de solventes, acarretou num aumento da solubilidade do beta-caroteno para todas as condições experimentais. Observou-se ainda, que nas condições experimentais investigadas, não houve sinergismo significativo para as misturas de solventes quando comparadas aos valores de solubilidade obtidos para os solventes puros. O modelo UNIFAC se mostrou útil na previsão qualitativa dos resultados de solubilidade.This work reports experimental data of the solubility of beta-carotene in pure acetone, ethyl acetate, ethanol and dichloromethane and in mixtures of these organic solvents in the temperature range of 10 to 60 °C under ambient pressure. The gravimetric method was employed to determine the solubility, using glass equilibrium cells. The results showed that the best solvents were those having solubility parameter values close to that of the solute. It was found that raising the temperature caused the solute solubility values for both pure and solvent mixtures to increase under all the experimental conditions. Moreover, no synergetic effects were observed on the solubility of beta-carotene in solvent mixtures compared to pure solvents in the temperature range investigated. The UNIFAC model proved to be useful in predicting the solubility data.

  15. TRAC-PF1: an advanced best-estimate computer program for pressurized water reactor analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liles, D.R.; Mahaffy, J.H.

    1984-02-01

    The Transient Reactor Analysis Code (TRAC) is being developed at the Los Alamos National Laboratory to provide advanced best-estimate predictions of postulated accidents in light water reactors. The TRAC-PF1 program provides this capability for pressurized water reactors and for many thermal-hydraulic experimental facilities. The code features either a one-dimensional or a three-dimensional treatment of the pressure vessel and its associated internals; a two-phase, two-fluid nonequilibrium hydrodynamics model with a noncondensable gas field; flow-regime-dependent constitutive equation treatment; optional reflood tracking capability for both bottom flood and falling-film quench fronts; and consistent treatment of entire accident sequences including the generation of consistent initial conditions. This report describes the thermal-hydraulic models and the numerical solution methods used in the code. Detailed programming and user information also are provided.

  16. A novel numerical model for estimating the collapse pressure of flexible pipes

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Victor P.P.; Antoun Netto, Theodoro [Universidade Federal do Rio de Janeiro (COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao em Engenharia], e-mail: victor@lts.coppe.ufrj.br

    2009-07-01

    As the worldwide oil and gas industry operational environments move to ultra-deep waters, failure mechanisms in flexible pipes such as instability of the armor layers under compression and hydrostatic collapse are more likely to occur. Therefore, it is important to develop reliable numerical tools to reproduce the failure mechanisms that may occur in flexible pipes. This work presents a representative finite element model of flexible pipe capable to reproduce its pre and post-collapse behavior under hydrostatic pressure. The model, developed in the scope of this work, uses beam elements and includes nonlinear kinematics and material behavior influences. The dependability of the numerical results is assessed in light of experimental tests on flexible pipes with 4 inches and 8 inches nominal diameter available in the literature (Souza, 2002). The applied methodology provided coherent values regarding the estimation of the collapse pressures and results have shown that the proposed model is capable to reproduce experimental results. (author)

  17. Review of external ocular compression: clinical applications of the ocular pressure estimator

    Directory of Open Access Journals (Sweden)

    Korenfeld MS

    2016-02-01

    Full Text Available Michael S Korenfeld,1,2 David K Dueker3 1Comprehensive Eye Care, Ltd. Washington, MO, USA; 2Washington University Department of Ophthalmology and Visual Sciences, St Louis, MO, USA; 3Ophthalmology, Hamad Medical Corporation, Doha, Qatar Purpose: The authors have previously validated an Ocular Pressure Estimator (OPE that can estimate the intraocular pressure (IOP during external ocular compression (EOC. The authors now apply the OPE in clinical states where EOC is clinically important. The original work is described for two periods of risk: during sleep and during the digital ocular massage (DOM maneuver used by surgeons after trabeculectomy to keep the operation functional. Other periods of risk for external ocular compression are then reviewed.Methods: The first protocol estimated the IOP in the dependent eye during simulated sleep. Subjects had their IOPs initially measured in an upright-seated position, immediately upon assuming a right eye dependent side sleeping position (with nothing contacting the eye, and then 5 minutes later while still in this position. While maintaining this position, the fluid filled bladder of the OPE was then placed between the subject’s closed eye and a pillow during simulated sleep. The IOP was continuously estimated in this position for 5 minutes. The subjects then had the IOP measured in both eyes in an upright-seated position. The second protocol determined if a larger vertical cup-to-disc ratio was more common on the side that patients reported they preferred to sleep on. The hypothesis was that chronic asymmetric, compression induced, elevations of IOP during sleep would be associated with otherwise unexplained asymmetry of the vertical cup-to-disc ratio. The third protocol assessed the IOP during DOM. The OPE was used to characterize the IOP produced during the DOM maneuver of five glaucoma surgeons. After this, 90 mmHg was chosen as a target pressure for DOM. The surgeons were then verbally coached

  18. In-situ spectroscopic monitoring of the ambient pressure hydrogenation of C2 to ethane on Pt(111)

    Science.gov (United States)

    Krooswyk, Joel D.; Kruppe, Christopher M.; Trenary, Michael

    2016-10-01

    The hydrogenation of C2 molecules formed on the Pt(111) surface through acetylene exposure at 750 K was monitored in-situ with reflection absorption infrared spectroscopy (RAIRS) in the presence of up to 10 Torr of H2. The coverage of post-reaction surface carbon was measured with Auger electron spectroscopy. The RAIR spectra show that C2 is hydrogenated to an ethylidyne intermediate. The hydrogenation of ethylidyne was also monitored at 400 K for H2(g) pressures of 1.0 × 10- 2 to 10 Torr. At H2(g) pressures greater than 1.0 Torr, ethylidyne is completely hydrogenated. In an attempt to probe the nature of the C2 adsorption sites, RAIR spectra of coadsorbed CO were obtained. It is found that while C2 does not block CO adsorption, the spectra indicate that the surface carbon is free of hydrogen. In contrast, ethylidyne blocks CO adsorption sites. In the presence of coadsorbed CO, complete hydrogenation of ethylidyne occurs at 450 K versus 400 K in the absence of CO.

  19. Practical considerations for the rapid screening for pesticides using ambient pressure desorption ionisation with high-resolution mass spectrometry.

    Science.gov (United States)

    Edison, S E; Lin, L A; Parrales, L

    2011-10-01

    A rapid screening method for pesticides has been developed to streamline the processing of produce entering the United States. Foam swabs were used to recover multi-class mixtures of 240, 140, 132 and 60 pesticides from the surfaces of apples, kiwis, peaches and tomatoes. The mixtures were selected to span a large range of chemical classes, polarities, solubilities and sizes to provide a broad look at how this technique will perform for a variety of analytes. The swabs were analysed using direct analysis in real-time (DART) ionisation coupled with a high-resolution Exactive Orbitrap™ mass spectrometer. This study expands the types of commodities analysed using this method and explores the feasibility of compositing multiple units of produce per batch to analyse a representative sample. It was established that whilst smooth-skinned produce, such as apples, maintained a high detection rate for the pesticide mixtures even when ten apples are swabbed with one foam disk, commodities with rougher surfaces, such as peaches, suffered a decrease in detection rate when ten peaches are swabbed with one foam disk. In order to maintain some consistency across the sample preparation process, a composite size of three units was selected. The varying topography of the commodities necessitated minor modifications to the method; for example, analysis of kiwi required that the hair on the surface be shaved prior to swabbing to achieve good recovery. Additionally, the effect of storage conditions on detection rate was analysed by spiking the surface of tomatoes at levels of 5 and 10 ng g(-1) for each pesticide, storing them under refrigeration and ambient conditions for 3 and 8 days, and then analysing the surface using this method. After 8 days of storage under both conditions more than 80% of the pesticides in the mixture were detected. Also, analysis of the multi-class mixtures was performed in both positive- and negative-ion mode and many classes were detected in both modes

  20. Multi-morphological growth of nano-structured In{sub 2}Se{sub 3} by ambient pressure triethylene glycol based solution syntheses

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tongfei; Wang, Jian; Lai, Junyun; Zheng, Xuerong; Liu, Weiyan; Ji, Junna [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Liu, Hui [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401 (China); Jin, Zhengguo, E-mail: zhgjin@tju.edu.cn [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

    2015-10-15

    In{sub 2}Se{sub 3} nanoparticles, flower-like shaped and sheet-shaped nanocrystals were synthesized by a new, facile, ambient pressure triethylene glycol based solution chemical route using indium(III) chloride and selenium powder as precursors. The growing morphology, crystallization, chemical stoichiometry and light absorption property of the In{sub 2}Se{sub 3} products synthesized were characterized by TEM, HRTEM, FESEM, XRD, EDX and UV–vis–NIR measurements. Multi-morphological growth of the nano-structured In{sub 2}Se{sub 3} in triethylene glycol based solution syntheses with changed assisting agents and reaction styles was demonstrated. - Highlights: • Multimorphological growth of In{sub 2}Se{sub 3} was demonstrated based on solution chemistry. • A new, facile, low cost and fast air pressure TEG based solution process was used. • Nanoparticles, flower-like shaped and sheet-shaped nanocrystals were synthesized. • Morphology, crystallization, stoichiometry and light absorption was characterized. • Solution growth of β-In{sub 2}Se{sub 3} nanosheets was firstly reported by this submission.

  1. Using "Tender" X-ray Ambient Pressure X-Ray Photoelectron Spectroscopy as A Direct Probe of Solid-Liquid Interface.

    Science.gov (United States)

    Axnanda, Stephanus; Crumlin, Ethan J; Mao, Baohua; Rani, Sana; Chang, Rui; Karlsson, Patrik G; Edwards, Mårten O M; Lundqvist, Måns; Moberg, Robert; Ross, Phil; Hussain, Zahid; Liu, Zhi

    2015-05-07

    We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a "dip &pull" method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, "dip &pull" approach, with a "tender" X-ray synchrotron source (2 keV-7 keV), we are able to access the interface between liquid and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt(2+) and Pt(4+) interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of "tender" AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry.

  2. Matching a statistical pressure snake to a four-sided polygon and estimating the polygon corners.

    Energy Technology Data Exchange (ETDEWEB)

    Schaub, Hanspeter (ORION International Technologies, Albuquerque, NM); Wilson, Chris C.

    2004-05-01

    Given a video image source, a statistical pressure snake is able to track a color target in real time. This report presents an algorithm that exploits the one-dimensional nature of the visual snake target outline. If the target resembles a four-sided polygon, then the four polygon sides are identified by mapping all image snake point coordinates into Hough space where lines become points. After establishing that four dominant lines are present in snake contour, the polygon corner points are estimated. The computation burden of this algorithm is of the N logN type. The advantage of this method is that it can provide real-time target corner estimates, even if the corners themselves might be occluded.

  3. Simplified Methodology to Estimate the Maximum Liquid Helium (LHe) Cryostat Pressure from a Vacuum Jacket Failure

    Science.gov (United States)

    Ungar, Eugene K.; Richards, W. Lance

    2015-01-01

    The aircraft-based Stratospheric Observatory for Infrared Astronomy (SOFIA) is a platform for multiple infrared astronomical observation experiments. These experiments carry sensors cooled to liquid helium temperatures. The liquid helium supply is contained in large (i.e., 10 liters or more) vacuum-insulated dewars. Should the dewar vacuum insulation fail, the inrushing air will condense and freeze on the dewar wall, resulting in a large heat flux on the dewar's contents. The heat flux results in a rise in pressure and the actuation of the dewar pressure relief system. A previous NASA Engineering and Safety Center (NESC) assessment provided recommendations for the wall heat flux that would be expected from a loss of vacuum and detailed an appropriate method to use in calculating the maximum pressure that would occur in a loss of vacuum event. This method involved building a detailed supercritical helium compressible flow thermal/fluid model of the vent stack and exercising the model over the appropriate range of parameters. The experimenters designing science instruments for SOFIA are not experts in compressible supercritical flows and do not generally have access to the thermal/fluid modeling packages that are required to build detailed models of the vent stacks. Therefore, the SOFIA Program engaged the NESC to develop a simplified methodology to estimate the maximum pressure in a liquid helium dewar after the loss of vacuum insulation. The method would allow the university-based science instrument development teams to conservatively determine the cryostat's vent neck sizing during preliminary design of new SOFIA Science Instruments. This report details the development of the simplified method, the method itself, and the limits of its applicability. The simplified methodology provides an estimate of the dewar pressure after a loss of vacuum insulation that can be used for the initial design of the liquid helium dewar vent stacks. However, since it is not an exact

  4. Air pollution and survival within the Washington University-EPRI veterans cohort: risks based on modeled estimates of ambient levels of hazardous and criteria air pollutants.

    Science.gov (United States)

    Lipfert, Frederick W; Wyzga, Ronald E; Baty, Jack D; Miller, J Philip

    2009-04-01

    For this paper, we considered relationships between mortality, vehicular traffic density, and ambient levels of 12 hazardous air pollutants, elemental carbon (EC), oxides of nitrogen (NOx), sulfur dioxide (SO2), and sulfate (SO4(2-)). These pollutant species were selected as markers for specific types of emission sources, including vehicular traffic, coal combustion, smelters, and metal-working industries. Pollutant exposures were estimated using emissions inventories and atmospheric dispersion models. We analyzed associations between county ambient levels of these pollutants and survival patterns among approximately 70,000 U.S. male veterans by mortality period (1976-2001 and subsets), type of exposure model, and traffic density level. We found significant associations between all-cause mortality and traffic-related air quality indicators and with traffic density per se, with stronger associations for benzene, formaldehyde, diesel particulate, NOx, and EC. The maximum effect on mortality for all cohort subjects during the 26-yr follow-up period is approximately 10%, but most of the pollution-related deaths in this cohort occurred in the higher-traffic counties, where excess risks approach 20%. However, mortality associations with diesel particulates are similar in high- and low-traffic counties. Sensitivity analyses show risks decreasing slightly over time and minor differences between linear and logarithmic exposure models. Two-pollutant models show stronger risks associated with specific traffic-related pollutants than with traffic density per se, although traffic density retains statistical significance in most cases. We conclude that tailpipe emissions of both gases and particles are among the most significant and robust predictors of mortality in this cohort and that most of those associations have weakened over time. However, we have not evaluated possible contributions from road dust or traffic noise. Stratification by traffic density level suggests the

  5. Positive association between short-term ambient air pollution exposure and children blood pressure in China-Result from the Seven Northeast Cities (SNEC) study.

    Science.gov (United States)

    Zeng, Xiao-Wen; Qian, Zhengmin Min; Vaughn, Michael G; Nelson, Erik J; Dharmage, Shyamali C; Bowatte, Gayan; Perret, Jennifer; Chen, Duo-Hong; Ma, Huimin; Lin, Shao; de Foy, Benjamin; Hu, Li-Wen; Yang, Bo-Yi; Xu, Shu-Li; Zhang, Chuan; Tian, Yan-Peng; Nian, Min; Wang, Jia; Xiao, Xiang; Bao, Wen-Wen; Zhang, Ya-Zhi; Dong, Guang-Hui

    2017-05-01

    The impact of ambient air pollution on health causes concerns in China. However, little is known about the association of short-term air pollution exposure with blood pressure (BP) in children. The goal of present study was to assess the association between short-term air pollution and BP in children from a highly polluted area in China. This study enrolled 9354 children in 24 elementary and middle schools (aged 5-17 years) from the Seven Northeast Cities (SNEC) study, respectively, during the period of 2012-2013. Ambient air pollutants, including particulate matter with an aerodynamic diameter of ≤10 μm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) on the days (1-5 days) preceding BP examination were collected from local air monitoring stations. Generalized additive models and two-level regression analyses were used to evaluate the relationship between air pollution and BP after adjusting for other covariates. Results showed that with an interquartile range (IQR) increase in PM10 (50.0 μg/m(3)) and O3 (53.0 μg/m(3)) level during the 5-day mean exposure, positive associations with elevated BP were observed, with an odds ratio of 2.17 (95% CI, 1.61-2.93) for PM10 and 2.77 (95% CI, 1.94-3.95) for O3. Both systolic BP and diastolic BP levels were positively associated with an IQR increase of four air pollutants at different lag times. Specifically, an IQR increase in the 5-day mean of PM10 and O3 was associated with elevation of 2.07 mmHg (95% CI, 1.71-2.44) and 3.29 mmHg (95% CI, 2.86-3.72) in systolic BP, respectively. When stratified by sex, positive relationships were observed for elevated BP with NO2 exposure only in males. This is the first report on the relationship between ambient short-term air pollution exposure and children BP in China. Findings indicate a need to control air pollutants and protect children from heavy air pollution exposure in China.

  6. A molecular dynamics study of ambient and high pressure phases of silica: Structure and enthalpy variation with molar volume

    Science.gov (United States)

    Rajappa, Chitra; Sringeri, S. Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J.

    2014-06-01

    Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, α-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume—for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase.

  7. Crack opening area estimates in pressurized through-wall cracked elbows under bending

    Energy Technology Data Exchange (ETDEWEB)

    Franco, C.; Gilles, P.; Pignol, M.

    1997-04-01

    One of the most important aspects in the leak-before-break approach is the estimation of the crack opening area corresponding to potential through-wall cracks at critical locations during plant operation. In order to provide a reasonable lower bound to the leak area under such loading conditions, numerous experimental and numerical programs have been developed in USA, U.K. and FRG and widely discussed in literature. This paper aims to extend these investigations on a class of pipe elbows characteristic of PWR main coolant piping. The paper is divided in three main parts. First, a new simplified estimation scheme for leakage area is described, based on the reference stress method. This approach mainly developed in U.K. and more recently in France provides a convenient way to account for the non-linear behavior of the material. Second, the method is carried out for circumferential through-wall cracks located in PWR elbows subjected to internal pressure. Finite element crack area results are presented and comparisons are made with our predictions. Finally, in the third part, the discussion is extended to elbows under combined pressure and in plane bending moment.

  8. Subject-specific biomechanics of trunk: musculoskeletal scaling, internal loads and intradiscal pressure estimation.

    Science.gov (United States)

    Ghezelbash, F; Shirazi-Adl, A; Arjmand, N; El-Ouaaid, Z; Plamondon, A

    2016-12-01

    Development of a subject-specific computational musculoskeletal trunk model (accounting for age, sex, body weight and body height), estimation of muscle forces and internal loads as well as subsequent validation by comparison with measured intradiscal pressure in various lifting tasks are novel, important and challenging. The objective of the present study is twofold. First, it aims to update and personalize the passive and active structures in an existing musculoskeletal kinematics-driven finite element model. The scaling scheme used an existing imaging database and biomechanical principles to adjust muscle geometries/cross-sectional-areas and passive joint geometry/properties in accordance with subjects' sex, age, body weight and body height. Second, using predictions of a detailed passive finite element model of the ligamentous lumbar spine, a novel nonlinear regression equation was proposed that relates the intradiscal pressure (IDP) at the L4-L5 disc to its compression force and intersegmental flexion rotation. Predicted IDPs and muscle activities of the personalized models under various tasks are found in good-to-excellent agreement with reported measurements. Results indicate the importance of personal parameters when computing muscle forces and spinal loads especially at larger trunk flexion angles as minor changes in individual parameters yielded up to 30 % differences in spinal forces. For more accurate subject-specific estimation of spinal loads and muscle activities, such a comprehensive trunk model should be used that accounts for subject's personalized features on active musculature and passive spinal structure.

  9. Estimating Stresses, Fault Friction and Fluid Pressure from Topography and Coseismic Slip Models

    Science.gov (United States)

    Styron, R. H.; Hetland, E. A.

    2014-12-01

    Stress is a first-order control on the deformation state of the earth. However, stress is notoriously hard to measure, and researchers typically only estimate the directions and relative magnitudes of principal stresses, with little quantification of the uncertainties or absolute magnitude. To improve upon this, we have developed methods to constrain the full stress tensor field in a region surrounding a fault, including tectonic, topographic, and lithostatic components, as well as static friction and pore fluid pressure on the fault. Our methods are based on elastic halfspace techniques for estimating topographic stresses from a DEM, and we use a Bayesian approach to estimate accumulated tectonic stress, fluid pressure, and friction from fault geometry and slip rake, assuming Mohr-Coulomb fault mechanics. The nature of the tectonic stress inversion is such that either the stress maximum or minimum is better constrained, depending on the topography and fault deformation style. Our results from the 2008 Wenchuan event yield shear stresses from topography up to 20 MPa (normal-sinistral shear sense) and topographic normal stresses up to 80 MPa on the faults; tectonic stress had to be large enough to overcome topography to produce the observed reverse-dextral slip. Maximum tectonic stress is constrained to be >0.3 * lithostatic stress (depth-increasing), with a most likely value around 0.8, trending 90-110°E. Minimum tectonic stress is about half of maximum. Static fault friction is constrained at 0.1-0.4, and fluid pressure at 0-0.6 * total pressure on the fault. Additionally, the patterns of topographic stress and slip suggest that topographic normal stress may limit fault slip once failure has occurred. Preliminary results from the 2013 Balochistan earthquake are similar, but yield stronger constraints on the upper limits of maximum tectonic stress, as well as tight constraints on the magnitude of minimum tectonic stress and stress orientation. Work in progress on

  10. Methods for estimating pressure and thermal loads induced by elevon deflections on hypersonic-vehicle surfaces with turbulent boundary layers

    Science.gov (United States)

    Kaufman, L. G., II; Johnson, C. B.

    1981-01-01

    Empirical anaytic methods are presented for calculating thermal and pressure distributions in three-dimensional, shock-wave turbulent-boundary-layer, interaction-flow regions on the surface of controllable hypersonic aircraft and missiles. The methods, based on several experimental investigations, are useful and reliable for estimating both the extent and magnitude of the increased thermal and pressure loads on the vehicle surfaces.

  11. Sublimation characterization and vapor pressure estimation of an HIV nonnucleoside reverse transcriptase inhibitor using thermogravimetric analysis.

    Science.gov (United States)

    Xie, Minli; Ziemba, Theresa M; Maurin, Michael B

    2003-01-01

    The purpose of this research is to investigate the sublimation process of DPC 963, a second-generation nonnucleoside reverse transcriptase inhibitor for HIV-1 retrovirus, and to better understand the effect of sublimation during active pharmaceutical ingredient (API) manufacture and formulation development, especially the drying processes. Sublimation of DPC 963 at 150 degrees C and above was determined by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR). The rates of sublimation at different temperatures were measured using isothermal TGA. Condensed material was collected and analyzed by differential scanning calorimetry (DSC), x-ray powder diffraction (XRPD), and infrared (IR) spectrometry. Benzoic acid was used as a reference standard to derive a linear logarithmic relationship between sublimation/evaporation rate and vapor pressure specific to the TGA system used in this study. Sublimation and evaporation of DPC 963 were found to follow apparent zero-order kinetics. Using the Eyring equation, the enthalpy and entropy of the sublimation and evaporation processes were obtained. The enthalpies of sublimation and evaporation were found to be 29 and 22 kcal/mol, respectively. The condensed material from the vapor phase was found to exist in 2 physical forms, amorphous and crystalline. Using benzoic acid as a reference standard, vapor pressure of DPC 963 at different temperatures was calculated using the linear logarithmic relationship obtained. DPC 963 undergoes sublimation at appreciable rates at 150 degrees C and above but this is not likely to pose a serious issue during the manufacturing process. Vapor pressure estimation using thermogravimetric analysis provided sufficient accuracy to be used as a fast, simple, and safe alternative to the traditional methods of vapor pressure determination.

  12. Ambient Space and Ambient Sensation

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    The ambient is the aesthetic production of the sensation of being surrounded. As a concept, 'ambient' is mostly used in relation to the music genre 'ambient music' and Brian Eno's idea of environmental background music. However, the production of ambient sensations must be regarded as a central...... aspect of the aesthetization of modern culture in general, from architecture, transport and urbanized lifeforms to film, sound art, installation art and digital environments. This presentation will discuss the key aspects of ambient aesthetization, including issues such as objectlessness...

  13. Ambient insect pressure and recipient genotypes determine fecundity of transgenic crop-weed rice hybrid progeny: Implications for environmental biosafety assessment.

    Science.gov (United States)

    Xia, Hui; Zhang, Hongbin; Wang, Wei; Yang, Xiao; Wang, Feng; Su, Jun; Xia, Hanbing; Xu, Kai; Cai, Xingxing; Lu, Bao-Rong

    2016-08-01

    Transgene introgression into crop weedy/wild relatives can provide natural selective advantages, probably causing undesirable environmental impact. The advantages are likely associated with factors such as transgenes, selective pressure, and genetic background of transgene recipients. To explore the role of the environment and background of transgene recipients in affecting the advantages, we estimated the fitness of crop-weed hybrid lineages derived from crosses between marker-free insect-resistant transgenic (Bt/CpTI) rice with five weedy rice populations under varied insect pressure. Multiway anova indicated the significant effect of both transgenes and weedy rice genotypes on the performance of crop-weed hybrid lineages in the high-insect environment. Increased fecundity was detected in most transgene-present F1 and F2 hybrid lineages under high-insect pressure, but varied among crop-weed hybrid lineages with different weedy rice parents. Increased fecundity of transgenic crop-weed hybrid lineages was associated with the environmental insect pressure and genotypes of their weedy rice parents. The findings suggest that the fitness effects of an insect-resistant transgene introgressed into weedy populations are not uniform across different environments and genotypes of the recipient plants that have acquired the transgene. Therefore, these factors should be considered when assessing the environmental impact of transgene flow to weedy or wild rice relatives.

  14. Experimental Research on Performance of Self-excited Inspiratory Pulsed Jet Device under Different Ambient Pressures%不同围压下自激吸气式脉冲射流装置性能试验研究

    Institute of Scientific and Technical Information of China (English)

    高传昌; 黄晓亮; 赵礼; 杜俐

    2011-01-01

    To address the technical problems of mud processing of deep water reservoirs and meet the urgent needs, experiments were conducted to assess the performance of a self-excited inspiratory pulsed jet device under different ambient pressures with testing device developed by ourselves, I n which the influence of the driving pressure, ambient pressure and standoff distance on the impact force of pulsed jet were analyzed. Preliminary research on the change of inspiratory quantity and start-up inspiratory pressure was also carried out. As the experimental results demonstrate, the pulsed jet impact force increases with the increase of driving pressure, but decreases with the increase of ambient pressure and standoff distance; the inspiratory capacity increases as driving pressure increases,at a speed varying according to the stimulus of ambient pressure ,and becomes stable gradually; start-up inspiratory pressure increases as ambient pressure increases,exhibiting certain regularity. The experiment provides basis for the in-depth study on self-excited inspiratory pulsed jet and its application in projects like reservoir desilting.%针对深水水库泥沙处理技术问题和需求的迫切性,运用自行研制的试验装置对不同围压(模拟不同水深)下的自激吸气式脉冲射流装置性能进行了试验,研究分析了工作压力、围压、靶距对脉冲射流冲击力的影响,并对装置吸气量的变化及启动吸气压力进行了初步分析.结果表明,脉冲射流冲击力随工作压力的增加而增大,随围压和靶距的增加而减小;装置吸气量随工作压力的增加而增大,增大的速度随围压的不同而不同,并逐渐趋于稳定;启动吸气压力随围压增加而增大,且表现出一定规律性.研究结果为进一步深入研究自激吸气式脉冲射流及其在水库清淤等工程应用方面提供依据.

  15. The critical assessment of vapour pressure estimation methods for use in modelling the formation of atmospheric organic aerosol

    Directory of Open Access Journals (Sweden)

    M. H. Barley

    2010-01-01

    Full Text Available A selection of models for estimating vapour pressures have been tested against experimental data for a set of compounds selected for their particular relevance to the formation of atmospheric aerosol by gas-liquid partitioning. The experimental vapour pressure data (all <100 Pa of 45 multifunctional compounds provide a stringent test of the estimation techniques, with a recent complex group contribution method providing the best overall results. The effect of errors in vapour pressures upon the formation of organic aerosol by gas-liquid partitioning in an atmospherically relevant example is also investigated. The mass of organic aerosol formed under typical atmospheric conditions was found to be very sensitive to the variation in vapour pressure values typically present when comparing estimation methods.

  16. EPISTEMOLOGIA AMBIENTAL

    OpenAIRE

    2012-01-01

    O livro Epistemologia Ambiental traz uma rica discussão sobre a questão ambiental, abordando teorias relevantes para o entendimento e interpretação da crise atual, orientando para a construção de novas racionalidades e a constituição de um saber ambiental. A obra vem compartimentada em cinco capítulos distribuídos em 240 páginas. 

  17. The Role of Ambient Gas and Pressure on the Structuring of Hard Diamond-Like Carbon Films Synthesized by Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Andrei C. Popescu

    2015-06-01

    Full Text Available Hard carbon thin films were synthesized on Si (100 and quartz substrates by the Pulsed Laser Deposition (PLD technique in vacuum or methane ambient to study their suitability for applications requiring high mechanical resistance. The deposited films’ surface morphology was investigated by scanning electron microscopy, crystalline status by X-ray diffraction, packing and density by X-ray reflectivity, chemical bonding by Raman and X-ray photoelectron spectroscopy, adherence by “pull-out” measurements and mechanical properties by nanoindentation tests. Films synthesized in vacuum were a-C DLC type, while films synthesized in methane were categorized as a-C:H. The majority of PLD films consisted of two layers: one low density layer towards the surface and a higher density layer in contact with the substrate. The deposition gas pressure played a crucial role on films thickness, component layers thickness ratio, structure and mechanical properties. The films were smooth, amorphous and composed of a mixture of sp3-sp2 carbon, with sp3 content ranging between 50% and 90%. The thickness and density of the two constituent layers of a film directly determined its mechanical properties.

  18. Chemistry of NOx on TiO2 Surfaces Studied by Ambient Pressure XPS: Products, Effect of UV Irradiation, Water, and Coadsorbed K(.).

    Science.gov (United States)

    Rosseler, Olivier; Sleiman, Mohamad; Montesinos, V Nahuel; Shavorskiy, Andrey; Keller, Valerie; Keller, Nicolas; Litter, Marta I; Bluhm, Hendrik; Salmeron, Miquel; Destaillats, Hugo

    2013-02-07

    Self-cleaning surfaces containing TiO2 nanoparticles have been postulated to efficiently remove NOx from the atmosphere. However, UV irradiation of NOx adsorbed on TiO2 also was shown to form harmful gas-phase byproducts such as HONO and N2O that may limit their depolluting potential. Ambient pressure XPS was used to study surface and gas-phase species formed during adsorption of NO2 on TiO2 and subsequent UV irradiation at λ = 365 nm. It is shown here that NO3(-), adsorbed on TiO2 as a byproduct of NO2 disproportionation, was quantitatively converted to surface NO2 and other reduced nitrogenated species under UV irradiation in the absence of moisture. When water vapor was present, a faster NO3(-) conversion occurred, leading to a net loss of surface-bound nitrogenated species. Strongly adsorbed NO3(-) in the vicinity of coadsorbed K(+) cations was stable under UV light, leading to an efficient capture of nitrogenated compounds.

  19. Recycling of CO2: Probing the Chemical State of the Ni(111) Surface during the Methanation Reaction with Ambient-Pressure X-Ray Photoelectron Spectroscopy.

    Science.gov (United States)

    Heine, Christian; Lechner, Barbara A J; Bluhm, Hendrik; Salmeron, Miquel

    2016-10-12

    Using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), we studied the adsorption and reactions of CO2 and CO2 + H2 on the Ni(111) surface to identify the surface chemical state and the nature of the adsorbed species during the methanation reaction. In 200 mTorr CO2, we found that NiO is formed from CO2 dissociation into CO and atomic oxygen. Additionally, carbonate (CO3(2-)) is present on the surface from further reaction of CO2 with NiO. The addition of H2 into the reaction environment leads to reduction of NiO and the disappearance of CO3(2-). At temperatures >160 °C, CO adsorbed on hollow sites, and atomic carbon and OH species are present on the surface. We conclude that the methanation reaction proceeds via dissociation of CO2, followed by reduction of CO to atomic carbon and its hydrogenation to methane.

  20. Detection of Amines and Ammonia with an Ambient Pressure Mass Spectrometer using a Corona Discharge Ion Source, in an Urban Atmosphere and in a Teflon Film Chamber

    Science.gov (United States)

    Alves, M.; Hanson, D. R.; Grieves, C.; Ortega, J. V.

    2015-12-01

    Amines and ammonia are an important group of molecules that can greatly affect atmospheric particle formation that can go on to impact cloud formation and their scattering of thermal and solar radiation, and as a result human health and ecosystems. In this study, an Ambient Pressure Mass Spectrometer (AmPMS) that is selective and sensitive to molecules with a high proton affinity, such as amines, was coupled with a newly built corona discharge ion source. AmPMS was used to monitor many different nitrogenous compound that are found in an urban atmosphere (July 2015, Minneapolis), down to the single digit pmol/mol level. Simultaneous to this, a proton transfer mass spectrometer also sampled the atmosphere through an inlet within 20 m of the AmPMS inlet. In another set of studies, a similar AmPMS was attached to a large Teflon film chamber at the Atmospheric Chemistry Division at NCAR (August 2015, Boulder). Exploratory studies are planned on the sticking of amines to the chamber walls as well as oxidizing the amine and monitoring products. Depending on the success of these studies, results will be presented on the reversability of amine partitioning and mass balance for these species in the chamber.

  1. Water-gas shift reaction on metal nanoclusters encapsulated in mesoporous ceria studied with ambient-pressure X-ray photoelectron spectroscopy.

    Science.gov (United States)

    Wen, Cun; Zhu, Yuan; Ye, Yingchun; Zhang, Shiran; Cheng, Fang; Liu, Yi; Wang, Paul; Tao, Franklin Feng

    2012-10-23

    Metal nanoclusters (Au, Pt, Pd, Cu) encapsulated in channels of mesoporous ceria (mp-CeO(2)) were synthesized. The activation energies of water-gas shift (WGS) reaction performed at oxide-metal interfaces of metal nanoclusters encapsulated in mp-CeO(2) (M@mp-CeO(2)) are lower than those of metal nanoclusters impregnated on ceria nanorods (M/rod-CeO(2)). In situ studies using ambient-pressure XPS (AP-XPS) suggested that the surface chemistry of the internal concave surface of CeO(2) pores of M@mp-CeO(2) is different from that of external surfaces of CeO(2) of M/rod-CeO(2) under reaction conditions. AP-XPS identified the metallic state of the metal nanoclusters of these WGS catalysts (M@mp-CeO(2) and M/rod-CeO(2)) under a WGS reaction condition. The lower activation energy of M@mp-CeO(2) in contrast to M/rod-CeO(2) is related to the different surface chemistry of the two types of CeO(2) under the same reaction condition.

  2. Development of numerical model to investigate the laser driven shock waves from aluminum target into ambient air at atmospheric pressure and its comparison with experiment

    Science.gov (United States)

    Shiva, S. Sai; Leela, Ch.; Chaturvedi, S.; Sijoy, C. D.; Kiran, P. Prem

    2017-01-01

    A one-dimensional, three-temperature (electron, ion and thermal radiation) numerical model was developed to study the laser induced shock wave (LISW) propagation from aluminum target in ambient air at atmospheric pressure. The hydrodynamic equations of mass, momentum and energy are solved by using an implicit scheme in Lagrangian form. The model considers the laser absorption to take place via inverse-bremsstrahlung due to electron-ion (e-i) process. The flux limited electron thermal energy transport due e-i and e-n thermal energy relaxation equations are solved implicitly. The experimental characterization of spatio-temporal evolution of the LISW in air generated by focusing a second harmonic (532 nm, 7ns) of Nd:YAG laser on to surface of Al is performed using shadowgraphy technique with a temporal resolution of 1.5 ns. The velocity of SW observed in the experiments over 0.2 µs-8 µs time scales was compared with the numerical results to understand the SW transition from planar to spherical evolution.

  3. Nonhomogeneous surface properties of parylene-C film etched by an atmospheric pressure He/O2 micro-plasma jet in ambient air

    Science.gov (United States)

    Wang, Tao; Yang, Bin; Chen, Xiang; Wang, Xiaolin; Yang, Chunsheng; Liu, Jingquan

    2016-10-01

    Surface properties of parylene-C film etched by an atmospheric pressure He/O2 micro-plasma jet in ambient air were investigated. The morphologies and chemical compositions of the etched surface were analyzed by optical microscopy, SEM, EDS, XPS and ATR-FTIR. The microscopy and SEM images showed the etched surface was nonhomogeneous with six discernable ring patterns from the center to the outside domain, which were composed of (I) a central region; (II) an effective etching region, where almost all of the parylene-C film was removed by the plasma jet with only a little residual parylene-C being functionalized with carboxyl groups (Cdbnd O, Osbnd Cdbnd O-); (III) an inner etching boundary; (IV) a middle etching region, where the film surface was smooth and partially removed; (V) an outer etching boundary, where the surface was decorated with clusters of debris, and (VI) a pristine parylene-C film region. The analysis of the different morphologies and chemical compositions illustrated the different localized etching process in the distinct regions. Besides, the influence of O2 flow rate on the surface properties of the etched parylene-C film was also investigated. Higher volume of O2 tended to weaken the nonhomogeneous characteristics of the etched surface and improve the etched surface quality.

  4. Development of a Statistical Model for Estimating Spatial and Temporal Ambient Ozone Patterns in the Sierra Nevada, California

    Directory of Open Access Journals (Sweden)

    Haiganoush K. Preisler

    2002-01-01

    Full Text Available Statistical approaches for modeling spatially and temporally explicit data are discussed for 79 passive sampler sites and 9 active monitors distributed across the Sierra Nevada, California. A generalized additive regression model was used to estimate spatial patterns and relationships between predicted ozone exposure and explanatory variables, and to predict exposure at nonmonitored sites. The fitted model was also used to estimate probability maps for season average ozone levels exceeding critical (or subcritical levels in the Sierra Nevada region. The explanatory variables — elevation, maximum daily temperature, and precipitation and ozone level at closest active monitor — were significant in the model. There was also a significant mostly east-west spatial trend. The between-site variability had the same magnitude as the error variability. This seems to indicate that there still exist important site features not captured by the variables used in the analysis and that may improve the accuracy of the predictive model in future studies. The fitted model using robust techniques had an overall R2 value of 0.58. The mean standard deviation for a predicted value was 6.68 ppb.

  5. EVAPORATION: a new vapour pressure estimation methodfor organic molecules including non-additivity and intramolecular interactions

    Directory of Open Access Journals (Sweden)

    S. Compernolle

    2011-09-01

    Full Text Available We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects, a method to predict (subcooled liquid pure compound vapour pressure p0 of organic molecules that requires only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: aldehydes, ketones, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA.

  6. Endotoxin and β-1,3-d-Glucan in Concentrated Ambient Particles Induce Rapid Increase in Blood Pressure in Controlled Human Exposures.

    Science.gov (United States)

    Zhong, Jia; Urch, Bruce; Speck, Mary; Coull, Brent A; Koutrakis, Petros; Thorne, Peter S; Scott, James; Liu, Ling; Brook, Robert D; Behbod, Behrooz; Gibson, Heike; Silverman, Frances; Mittleman, Murray A; Baccarelli, Andrea A; Gold, Diane R

    2015-09-01

    Short-term exposure to particulate matter (PM) is associated with increased blood pressure (BP) in epidemiological studies. Understanding the impact of specific PM components on BP is essential in developing effective risk-reduction strategies. We investigated the association between endotoxin and β-1,3-d-Glucan-two major biological PM components-and BP. We also examined whether vascular endothelial growth factor, a vasodilatory inflammatory marker, modified these associations. We conducted a single-blind, randomized, crossover trial of controlled human exposure to concentrated ambient particles with 50 healthy adults. Particle-associated-endotoxin and β-1,3-d-Glucan were sampled using polycarbonate-membrane-filters. Supine resting systolic BP and diastolic BP were measured pre-, 0.5-hour post-, and 20-hour postexposure. Urine vascular endothelial growth factor concentration was determined using enzyme-linked immunosorbant assay and creatinine-corrected. Exposures to endotoxin and β-1,3-d-Glucan for 130 minutes were associated with increases in BPs: at 0.5-hour postexposure, every doubling in endotoxin concentration was associated with 1.73 mm Hg higher systolic BP (95% confidence interval, 0.28, 3.18; P=0.02) and 2.07 mm Hg higher diastolic BP (95% confidence interval, 0.74, 3.39; P=0.003); every doubling in β-1,3-d-Glucan concentration was associated with 0.80 mm Hg higher systolic BP (95% confidence interval, -0.07, 1.67; P=0.07) and 0.88 mm Hg higher diastolic BP (95% confidence interval, 0.09, 1.66; P=0.03). Vascular endothelial growth factor rose after concentrated ambient particle endotoxin exposure and attenuated the association between endotoxin and 0.5-hour postexposure diastolic BP (Pinteraction=0.02). In healthy adults, short-term endotoxin and β-1,3-d-Glucan exposures were associated with increased BP. Our findings suggest that the biological PM components contribute to PM-related cardiovascular outcomes, and postexposure vascular endothelial

  7. Limitations of stroke volume estimation by non-invasive blood pressure monitoring in hypergravity.

    Directory of Open Access Journals (Sweden)

    Olivier Manen

    Full Text Available Altitude and gravity changes during aeromedical evacuations induce exacerbated cardiovascular responses in unstable patients. Non-invasive cardiac output monitoring is difficult to perform in this environment with limited access to the patient. We evaluated the feasibility and accuracy of stroke volume estimation by finger photoplethysmography (SVp in hypergravity.Finger arterial blood pressure (ABP waveforms were recorded continuously in ten healthy subjects before, during and after exposure to +Gz accelerations in a human centrifuge. The protocol consisted of a 2-min and 8-min exposure up to +4 Gz. SVp was computed from ABP using Liljestrand, systolic area, and Windkessel algorithms, and compared with reference values measured by echocardiography (SVe before and after the centrifuge runs.The ABP signal could be used in 83.3% of cases. After calibration with echocardiography, SVp changes did not differ from SVe and values were linearly correlated (p<0.001. The three algorithms gave comparable SVp. Reproducibility between SVp and SVe was the best with the systolic area algorithm (limits of agreement -20.5 and +38.3 ml.Non-invasive ABP photoplethysmographic monitoring is an interesting technique to estimate relative stroke volume changes in moderate and sustained hypergravity. This method may aid physicians for aeronautic patient monitoring.

  8. Det ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Om begrebet "det ambiente", der beskriver, hvad der sker, når vi fornemmer baggrundsmusikkens diskrete beats, betragter udsigten gennem panoramavinduet eller tager 3D-brillerne på og læner os tilbage i biografsædet. Bogen analyserer, hvorfan ambiente oplevelser skabes, og hvilke konsekvenser det...

  9. Ambient Sensors

    NARCIS (Netherlands)

    Börner, Dirk; Specht, Marcus

    2014-01-01

    This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under th

  10. Derecho Ambiental

    OpenAIRE

    2014-01-01

    Es indudable la relevancia para la vida del planeta proteger el ambiente. De ahí que a lo largo de las últimas decadas el derecho ambiental se ha consolidado como una nueva y vital rama del derecho público.

  11. Ambient-pressure organic superconductor

    Science.gov (United States)

    Williams, Jack M.; Wang, Hsien-Hau; Beno, Mark A.

    1986-01-01

    A new class of organic superconductors having the formula (ET).sub.2 MX.sub.2 wherein ET represents bis(ethylenedithio)-tetrathiafulvalene, M is a metal such as Au, Ag, In, Tl, Rb, Pd and the like and X is a halide. The superconductor (ET).sub.2 AuI.sub.2 exhibits a transition temperature of 5 K which is high for organic superconductors.

  12. Models of venous return and their application to estimate the mean systemic filling pressure

    NARCIS (Netherlands)

    Hartog, E.A. den

    2007-01-01

    Mean systemic filling pressure is the equilibrium pressure in the systemic circulation when the heart is arrested and there is no flow. This pressure is a measure of the stressed volume of the systemic circulation and regarded as the driving pressure for the venous return during steady states [1-3].

  13. Models of venous return and their application to estimate the mean systemic filling pressure

    NARCIS (Netherlands)

    E.A. den Hartog (Emiel)

    1997-01-01

    textabstractMean systemic filling pressure is the equilibrium pressure in the systemic circulation when the heart is arrested and there is no flow. This pressure is a measure of the stressed volume of the systemic circulation and regarded as the driving pressure for the venous return during steady s

  14. Det Ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Det ambiente er iscenesættelsen af en karakteristisk sanseoplevelse, der er kendetegnet ved fornemmelsen af at være omgivet. I dag bliver begrebet om det ambiente mest anvendt i forbindelse med musikgenren ’ambient musik’. Det ambiente er dog ikke essentielt knyttet til det musikalske, men må...... forstås som et betydeligt bredere fænomen i den moderne æstetiske kultur, der spiller en væsentlig rolle i oplevelsen af moderne transportformer, arkitektur, film, lydkunst, installationskunst og digitale multimedieiscenesættelser. En forståelse af det ambiente er derfor centralt for forståelsen af en...... moderne æstetiseret oplevelseskultur i almindelighed. Da det ambiente ikke hidtil har været gjort til genstand for en mere indgående teoretisk behandling, er der dog stor usikkerhed omkring, hvad fænomenet overhovedet indebærer. Hovedformålet med Det ambiente – Sansning, medialisering, omgivelse er derfor...

  15. 常压干燥制备SiO2气凝胶的研究%Preparation of Silica Aerogel via Ambient Pressure Drying

    Institute of Scientific and Technical Information of China (English)

    吕鹏鹏; 赵海雷; 刘欣; 李兴旺

    2012-01-01

    Hydrophobic silica aerogel was prepared from commercial water glass via ambient pressure drying. The effects of aging times, aging agents, drying solvent categories and surface modification on the microstructure and properties of silica aerogel were investigated. The results showed that the den-sity, porosity and specific surface area of the prepared silica aerogel were 0. 082g/cm3, 96. 26% and 585. 4m2/g, respectively. The structure and properties of hydrophobic silica aerogel were analyzed by scanning electron microscope(SEM), Fourier transform infrared spectra ( FT-IR), thermogravimetric (TG) and differential thermal analysis(DTA).%以水玻璃为硅源,采用常压干燥制备了SiO2气凝胶.研究了老化时间、老化剂种类、干燥溶剂种类以及表面改性对SiO2气凝胶结构和性能的影响.结果表明:制得的SiO2气凝胶具有良好的疏水性,密度为0.082g/cm3,孔隙率为96.26%,比表面积达到585.4m2/g.采用扫描电镜(SEM)、傅里叶变换红外分析(FT-IR)、热重分析(TG)、差热分析(DTA)等对疏水型气凝胶的结构和性能进行了研究.

  16. A cost-effective and fast synthesis of nanoporous SiO 2 aerogel powders using water-glass via ambient pressure drying route

    Science.gov (United States)

    Bhagat, Sharad D.; Kim, Yong-Ha; Moon, Myung-Jun; Ahn, Young-Soo; Yeo, Jeong-Gu

    2007-07-01

    Considering the need for large-scale production of silica aerogel powders, the present research was aimed to develop a simple, cost-effective and rapid process based on water-glass precursor via ambient pressure drying (APD) route. It has been shown that the surface chemical modification of hydrogels can rapidly be carried out with extremely low doses (e.g. 5 g of hexamethyldisilazane ( HMDS) for 100 g of hydrogel) of HMDS by a co-precursor method which makes this process quite cost-effective. The surface modification in the aqueous phase essentially resulted in the displacement of the pore water and the simultaneous one-step solvent exchange using n-hexane converted the hydrogel into an organo-gel in 3 h and thus the total processing time of the aerogel powder production via APD could drastically be reduced to 5 h. The solvent n-hexane could be recollected during the drying stage and it does not add much to the material cost. The aerogel powders with tapping densities and specific surface areas in the range of 0.100-0.309 g/cm 3 and 473-776 m 2/g, respectively, could be synthesized using this novel route. The surface modification of the aerogel powders was explored by means of X-ray photoelectron spectroscopy (XPS) in conjunction with the Fourier transform infrared (FT-IR) spectroscopy. The textural investigations revealed that the aerogel powders with a wide variation in their pore size distributions and average pore diameters can easily be synthesized by varying the silica content in the sol.

  17. Growth of (Y1-x Ca x )Ba2Cu4O8 in ambient pressure and its tri-axial magnetic alignment

    Science.gov (United States)

    Horii, S.; Yamaki, M.; Shimoyama, J.; Kishio, K.; Doi, T.

    2015-10-01

    We report the growth of single crystals in ambient pressure and tri-axial orientation under modulated rotation magnetic fields (MRFs) for (Y1-x Ca x )Ba2Cu4O8 [(Y1-x Ca x )124] with x ≤ 0.1. Rectangular (Y1-x Ca x )124 crystals approximately 50 μm in size have been successfully grown for x ≤ 0.1 in a growth temperature region from 650 °C to 750 °C. Their critical temperatures increased with x and exhibited approximately 91 K for x = 0.1. By applying an MRF of 10 T, pulverised powders of (Y1-x Ca x )124 were tri-axially aligned in epoxy resin at room temperature in a whole x region below x = 0.1. The magnitude relationship of the magnetic susceptibilities (χ) along crystallographic directions for (Y1-x Ca x )124 was χ c > χ a > χ b at room temperature and was unchanged with a change in x. From changes in the degrees of the c-axis and the in-plane orientation (Δω) for the (Y1-x Ca x )124 powder samples aligned under three different MRF conditions, it was found that MRFs above at least 1 T were required to achieve almost complete tri-axial alignment with Δω introduction of magnetic alignment without using single crystalline samples. The present study indicates that magnetic alignment is a useful process for the fabrication of quasi-single-crystals from the perspective of solid-state physics and the production of cuprate superconducting materials.

  18. The echocardiographic estimation of left ventricular filling pressures in patients with mitral valve stenosis

    Directory of Open Access Journals (Sweden)

    Sattarzadeh Badkoubeh R

    2010-08-01

    Full Text Available "nBackground: Estimation of Left Ventricular End Diastolic Pressure (LVEDP among patients with Mitral Stenosis (MS helps to diagnose diastolic dysfunction and to explain their symptoms. However, Conventional Doppler measurements have limitation in predicting of LVEDP. This study sought to establish whether the correlation between measurements derived from Tissue Doppler echocardiography and LVEDP remains valid in the setting of severe mitral stenosis. "n"nMethods: Thirty three patients with moderate to severe MS who had indication for left heart catheterization enrolled during 1387-88 in Imam Khomeini Hospital in Tehran, Iran. The mean diastolic transmitral pressure gradient and mitral valve area (MVA were calculated, and Two-dimensional, M-mode, color Doppler and tissue Doppler Imaging indices such as: early diastolic mitral inflow velocity (E, annular early diastolic velocity (Ea, E/A ratio, Isovolemic relaxation time (IVRT, Pulmonary Vein systolic and diastolic flow velocities, Velocity Propagation, LA size, TE-Ea, Tei Index were obtained in maximum three hours before cardiac catheterization. The echocardiography analysis was performed offline without knowledge of hemodynamic data Linear correlation and multiple linear regression were used for analysis. p< 0.05 was considered significant. "n"nResults: In univariate analysis, E/Ea was associated with LVEDP significantly (p = 0.04, r = 0.38. There was also a significant correlation between TE-Ea and LVDP (p = 0.01, r = -0.44. In multiple linear regression Tei Index (ß = 0.4, p< 0.02, and TE-Ea (ß = 0.5, p = 0.02 were showed as independent predictors of LVEDP (R2 = 49%. "n"nConclusion: Although we observed a moderate correlation between Doppler measurements and LVEDP in patients with severe MS, more similar studies are required.

  19. Estimation of benchmark dose as the threshold amount of alcohol consumption for blood pressure in Japanese workers.

    Science.gov (United States)

    Suwazono, Yasushi; Sakata, Kouichi; Oishi, Mitsuhiro; Okubo, Yasushi; Dochi, Mirei; Kobayashi, Etsuko; Kido, Teruhiko; Nogawa, Koji

    2007-12-01

    In order to determine the threshold amount of alcohol consumption for blood pressure, we calculated the benchmark dose (BMD) of alcohol consumption and its 95% lower confidence interval (BMDL) in Japanese workers. The subjects consisted of 4,383 males and 387 females in a Japanese steel company. The target variables were systolic, diastolic, and mean arterial pressures. The effects of other potential covariates such as age and body mass index were adjusted by including these covariates in the multiple linear regression models. In male workers, BMD/BMDL for alcohol consumption (g/week) at which the probability of an adverse response was estimated to increase by 5% relative to no alcohol consumption, were 396/315 (systolic blood pressure), 321/265 (diastolic blood pressure), and 326/269 (mean arterial pressures). These values were based on significant regression coefficients of alcohol consumption. In female workers, BMD/BMDL for alcohol consumption based on insignificant regression coefficients were 693/134 (systolic blood pressure), 199/90 (diastolic blood pressure), and 267/77 (mean arterial pressure). Therefore, BMDs/BMDLs in males were more informative than those in females as there was no significant relationship between alcohol and blood pressure in females. The threshold amount of alcohol consumption determined in this study provides valuable information for preventing alcohol-induced hypertension.

  20. Clinical Commentary: How to Choose Blood Pressure Goals and Treatment: Influence of Estimated Glomerular Filtration Rate and Albuminuria

    Science.gov (United States)

    Weir, Matthew R.

    2008-01-01

    Objective measures of cardiovascular disease are often lacking until patients develop symptoms associated with either coronary, cerebral or peripheral vascular disease. Estimating risk for cardiovascular disease is often based on classic Framingham Heart Study criteria, such as age, gender, blood pressure, cholesterol, glucose levels and family history. Moreover, there is a well described continuous relationship between blood pressure, cholesterol, and glucose and risk for cardiovascular events. Estimating GFR, using simple formulae, and screening quantitatively for albuminuria may provide an important opportunity for identifying patients at increased risk for cardiovascular events. These safe, simple and cost-effective measures of estimating cardiovascular disease risk can be used not only to estimate cardiovascular disease burden, but also to gauge the adequacy of response to cardiovascular risk-reducing therapies. PMID:18596856

  1. 围压下磨料射流喷射套管及灰岩实验研究%Experimental study on abrasive water jet blasting casing and limestone under ambient pressures

    Institute of Scientific and Technical Information of China (English)

    黄中伟; 李根生; 史怀忠; 牛继磊; 宋先知; 邵尚奇

    2014-01-01

    在设计可承受围压的磨料射流喷射实验装置基础上,选取低孔低渗的石灰岩及套管试件,改变喷射压力、围压、喷嘴直径、喷射距离等因素,分析磨料射流切割套管及岩心的特性。结果表明,喷射压力、喷嘴直径等是影响磨料射流喷射效果的主要控制因素,喷射压力及喷嘴直径越大,喷射效果越好,射孔深度越深;射穿套管的时间对喷距及围压较为敏感,但岩样中的射孔深度对二者变化时的响应较小。%On the basis of the experimental device design for the abrasive water jet under ambient pressures, the low porosity and permeability limestone and the casing were selected to investigate the characteristics of casing cutting with abrasive water jet and sample core by changing the parameters of nozzle pressure drop, ambient pressure, nozzle diameter, and stand-off distance, etc. The results show that the nozzle pressure drop and nozzle diameter are the critical factors affecting the perfora-tion depth. The depth increases with the nozzle pressure drop and diameter going up. And the perforation time is more sensi-tive to the stand-off distance and ambient pressure. However, the perforation depth of the sample core has less response to the variation of the above two parameters.

  2. Numerical Estimation of Incident Wave Parameters Based on the Air Pressure Measurements in Pico OWC Plant

    Energy Technology Data Exchange (ETDEWEB)

    Le Crom, I.; Brito-Melo, A.; Newman, F. Sarmento, A. [Wave Energy Centre, Av. Manuel da Maia, 36, r/c D., Lisbon (Portugal)

    2009-07-01

    The present study aims at assessing the key spectral parameters of the incident wave on a fixed oscillating water column (OWC) device, based on the air pressure measurements inside the chamber and on the numerical hydrodynamic coefficients of the device. The methodology is based on the equation of continuity of the air in the time-domain and linear decomposition of the air flow in the usual terms of radiation and diffraction flows. By applying the Fast Fourier Transform, the time-domain equation is transposed to the respective frequency-domain equation. This methodology was applied to the 400 kW OWC power plant, on the Island of Pico, Azores, which has been monitored since 2005 by the Wave Energy Centre. The numerical hydrodynamic coefficients obtained by the 3D radiation-diffraction boundary element code, AQUADYN-OWC, were used in this study. No measurements of the incident wave in front of the plant are available; therefore the results obtained for a set of records are compared with forecast estimations for the site of Pico plant provided by INETI and also with the measurements of two directional wave rider buoys offshore Pico and Terceira islands. These data are provided by the Centre of Climate, Meteorology and Global Changes and propagated via the SWAN spectral wave model to the zone of interest. Final objective is to improve the control of the Pico plant by assessing its performance for a range of sea states.

  3. Historical Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Historical Ambient Air Quality Data Inventory contains measured and estimated data on ambient air pollution for use in assessing air quality, assisting in...

  4. Turbine airfoil with ambient cooling system

    Science.gov (United States)

    Campbell, Jr, Christian X.; Marra, John J.; Marsh, Jan H.

    2016-06-07

    A turbine airfoil usable in a turbine engine and having at least one ambient air cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels configured to receive ambient air at about atmospheric pressure. The ambient air cooling system may have a tip static pressure to ambient pressure ratio of at least 0.5, and in at least one embodiment, may include a tip static pressure to ambient pressure ratio of between about 0.5 and about 3.0. The cooling system may also be configured such that an under root slot chamber in the root is large to minimize supply air velocity. One or more cooling channels of the ambient air cooling system may terminate at an outlet at the tip such that the outlet is aligned with inner surfaces forming the at least one cooling channel in the airfoil to facilitate high mass flow.

  5. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources.

    Science.gov (United States)

    Shavorskiy, Andrey; Neppl, Stefan; Slaughter, Daniel S; Cryan, James P; Siefermann, Katrin R; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P; Zegkinoglou, Ioannis; Fraund, Matthew W; Khurmi, Champak; Hertlein, Marcus P; Wright, Travis W; Huse, Nils; Schoenlein, Robert W; Tyliszczak, Tolek; Coslovich, Giacomo; Robinson, Joseph; Kaindl, Robert A; Rude, Bruce S; Ölsner, Andreas; Mähl, Sven; Bluhm, Hendrik; Gessner, Oliver

    2014-09-01

    An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with

  6. Preparation of silica aerogel powder by ambient pressure drying%常压干燥法制备SiO2气凝胶粉体

    Institute of Scientific and Technical Information of China (English)

    王冬冬; 丁书强; 王自强; 王泽华; 陈伟

    2011-01-01

    Silica aerogel powder was prepared from industrial silica sols by ambient pressure drying and controlling the gelatin process and drying conditions. The effects of tetraethoxysilane (TEOS) content in aging solution and the drying control chemical additive (DCCA) on the density, specific surface,and pore size distribution of the SiO2 aerogel powder were investigated. The results show that; ( 1 ) the aerogels are nano-porous net structure of the spherical primary nanoparticles of 10-25 nm and the nano-metric pores of 5-50 nm;(2)With the temperature rising from room temperature to 1 100 ℃,the silica aerogels change from the amorphous phase to cristobalite; (3)the nano-network of silica aerogel powder can be strengthened by aging in mixture of TEOS and ethanol;(4)the addition of DCCA can improve the pore size distribution and increase the specific surface area of silica aerogel powders.%以工业硅溶胶为原料,通过凝胶过程与干燥条件的控制,采用常压干燥法制备了SiO2 气凝胶粉体,并考察了老化液中正硅酸乙脂(TEOS)含量和干燥控制化学添加荆甲酰胺的添加对气凝胶粉体堆积密度、比表面积和孔径分布的影响.结果表明:所得气凝胶粉体具有纳米多孔结构,组成气凝胶结构的基本粒子呈圆球形,粒径为10~25 nm,由基本粒子连接而成的网络结构具有5~50 nm的孔径分布;随着热处理温度从常温升至1 100℃,SiO2气凝胶从最初的无定形态转化为方石英;在,TEOS的醇溶液中老化,有利于增强凝胶骨架的强度;添加甲酰胺可以改善气凝胶粉体的孔径分布,提高其比表面积.

  7. Estimating Hydraulic Conductivities in a Fractured Shale Formation from Pressure Pulse Testing and 3d Modeling

    Science.gov (United States)

    Courbet, C.; DICK, P.; Lefevre, M.; Wittebroodt, C.; Matray, J.; Barnichon, J.

    2013-12-01

    In the framework of its research on the deep disposal of radioactive waste in shale formations, the French Institute for Radiological Protection and Nuclear Safety (IRSN) has developed a large array of in situ programs concerning the confining properties of shales in their underground research laboratory at Tournemire (SW France). One of its aims is to evaluate the occurrence and processes controlling radionuclide migration through the host rock, from the disposal system to the biosphere. Past research programs carried out at Tournemire covered mechanical, hydro-mechanical and physico-chemical properties of the Tournemire shale as well as water chemistry and long-term behaviour of the host rock. Studies show that fluid circulations in the undisturbed matrix are very slow (hydraulic conductivity of 10-14 to 10-15 m.s-1). However, recent work related to the occurrence of small scale fractures and clay-rich fault gouges indicate that fluid circulations may have been significantly modified in the vicinity of such features. To assess the transport properties associated with such faults, IRSN designed a series of in situ and laboratory experiments to evaluate the contribution of both diffusive and advective process on water and solute flux through a clay-rich fault zone (fault core and damaged zone) and in an undisturbed shale formation. As part of these studies, Modular Mini-Packer System (MMPS) hydraulic testing was conducted in multiple boreholes to characterize hydraulic conductivities within the formation. Pressure data collected during the hydraulic tests were analyzed using the nSIGHTS (n-dimensional Statistical Inverse Graphical Hydraulic Test Simulator) code to estimate hydraulic conductivity and formation pressures of the tested intervals. Preliminary results indicate hydraulic conductivities of 5.10-12 m.s-1 in the fault core and damaged zone and 10-14 m.s-1 in the adjacent undisturbed shale. Furthermore, when compared with neutron porosity data from borehole

  8. Estimation of Power Production Potential from Natural Gas Pressure Reduction Stations in Pakistan Using ASPEN HYSYS

    Directory of Open Access Journals (Sweden)

    Imran Nazir Unar

    2015-07-01

    Full Text Available Pakistan is a gas rich but power poor country. It consumes approximately 1, 559 Billion cubic feet of natural gas annually. Gas is transported around the country in a system of pressurized transmission pipelines under a pressure range of 600-1000 psig exclusively operated by two state owned companies i.e. SNGPL (Sui Northern Gas Pipelines Limited and SSGCL (Sui Southern Gas Company Limited. The gas is distributed by reducing from the transmission pressure into distribution pressure up to maximum level of 150 psig at the city gate stations normally called SMS (Sales Metering Station. As a normal practice gas pressure reduction at those SMSs is accomplished in pressure regulators (PCVs or in throttle valves where isenthalpic expansion takes place without producing any energy. Pressure potential of natural gas is an untapped energy resource which is currently wasted by its throttling. This pressure reduction at SMS (pressure drop through SMS may also be achieved by expansion of natural gas in TE, which converts its pressure into the mechanical energy, which can be transmitted any loading device for example electric generator. The aim of present paper is to explore the expected power production potential of various Sales Metering Stations of SSGCL company in Pakistan. The model of sales metering station was developed in a standard flow sheeting software Aspen HYSYS®7.1 to calculate power and study other parameters when an expansion turbine is used instead of throttling valves. It was observed from the simulation results that a significant power (more than 140 KW can be produced at pressure reducing stations of SSGC network with gas flows more than 2.2 MMSCFD and pressure ration more than 1.3.

  9. Estimation of the maximum contraction velocity of the urinary bladder from pressure and flow throughout micturition.

    NARCIS (Netherlands)

    R. van Mastrigt (Ron)

    1990-01-01

    textabstractThe contractility of the urinary bladder can be adequately described in terms of the parameters P0 (isometric pressure) and Vmax (maximum contraction velocity). In about 12% of urodynamic evaluations of patients these clinically relevant parameters can be calculated from pressure and flo

  10. Subject-specific estimation of central aortic blood pressure via system identification: preliminary in-human experimental study.

    Science.gov (United States)

    Fazeli, Nima; Kim, Chang-Sei; Rashedi, Mohammad; Chappell, Alyssa; Wang, Shaohua; MacArthur, Roderick; McMurtry, M Sean; Finegan, Barry; Hahn, Jin-Oh

    2014-10-01

    This paper demonstrates preliminary in-human validity of a novel subject-specific approach to estimation of central aortic blood pressure (CABP) from peripheral circulatory waveforms. In this "Individualized Transfer Function" (ITF) approach, CABP is estimated in two steps. First, the circulatory dynamics of the cardiovascular system are determined via model-based system identification, in which an arterial tree model is characterized based on the circulatory waveform signals measured at the body's extremity locations. Second, CABP waveform is estimated by de-convolving peripheral circulatory waveforms from the arterial tree model. The validity of the ITF approach was demonstrated using experimental data collected from 13 cardiac surgery patients. Compared with the invasive peripheral blood pressure (BP) measurements, the ITF approach yielded significant reduction in errors associated with the estimation of CABP, including 1.9-2.6 mmHg (34-42 %) reduction in BP waveform errors (p < 0.05) as well as 5.8-9.1 mmHg (67-76 %) and 6.0-9.7 mmHg (78-85 %) reductions in systolic and pulse pressure (SP and PP) errors (p < 0.05). It also showed modest but significant improvement over the generalized transfer function approach, including 0.1 mmHg (2.6 %) reduction in BP waveform errors as well as 0.7 (20 %) and 5.0 mmHg (75 %) reductions in SP and PP errors (p < 0.05).

  11. Ambient intelligence

    OpenAIRE

    Sanders, David; Gegov, Alexander

    2006-01-01

    This paper considers some history and the state of the art of Ambient Intelligence and from that seeks to identify new topics and future work. Ubiquitous computing, communications, human-centric computer interaction, embedded systems, context awareness, adaptive systems and distributed device networks are considered.

  12. The impact of intraocular pressure on elastic wave velocity estimates in the crystalline lens

    Science.gov (United States)

    Park, Suhyun; Yoon, Heechul; Larin, Kirill V.; Emelianov, Stanislav Y.; Aglyamov, Salavat R.

    2017-02-01

    Intraocular pressure (IOP) is believed to influence the mechanical properties of ocular tissues including cornea and sclera. The elastic properties of the crystalline lens have been mainly investigated with regard to presbyopia, the age-related loss of accommodation power of the eye. However, the relationship between the elastic properties of the lens and IOP remains to be established. The objective of this study is to measure the elastic wave velocity, which represents the mechanical properties of tissue, in the crystalline lens ex vivo in response to changes in IOP. The elastic wave velocities in the cornea and lens from seven enucleated bovine globe samples were estimated using ultrasound shear wave elasticity imaging. To generate and then image the elastic wave propagation, an ultrasound imaging system was used to transmit a 600 µs pushing pulse at 4.5 MHz center frequency and to acquire ultrasound tracking frames at 6 kHz frame rate. The pushing beams were separately applied to the cornea and lens. IOP in the eyeballs was varied from 5 to 50 mmHg. The results indicate that while the elastic wave velocity in the cornea increased from 0.96  ±  0.30 m s-1 to 6.27  ±  0.75 m s-1 as IOP was elevated from 5 to 50 mmHg, there were insignificant changes in the elastic wave velocity in the crystalline lens with the minimum and the maximum speeds of 1.44  ±  0.27 m s-1 and 2.03  ±  0.46 m s-1, respectively. This study shows that ultrasound shear wave elasticity imaging can be used to assess the biomechanical properties of the crystalline lens noninvasively. Also, it was observed that the dependency of the crystalline lens stiffness on the IOP was significantly lower in comparison with that of cornea.

  13. Intracranial pressure monitoring, cerebral perfusion pressure estimation, and ICP/CPP-guided therapy: a standard of care or optional extra after brain injury?

    Science.gov (United States)

    Kirkman, M A; Smith, M

    2014-01-01

    Measurement of intracranial pressure (ICP) and mean arterial pressure (MAP) is used to derive cerebral perfusion pressure (CPP) and to guide targeted therapy of acute brain injury (ABI) during neurointensive care. Here we provide a narrative review of the evidence for ICP monitoring, CPP estimation, and ICP/CPP-guided therapy after ABI. Despite its widespread use, there is currently no class I evidence that ICP/CPP-guided therapy for any cerebral pathology improves outcomes; indeed some evidence suggests that it makes no difference, and some that it may worsen outcomes. Similarly, no class I evidence can currently advise the ideal CPP for any form of ABI. 'Optimal' CPP is likely patient-, time-, and pathology-specific. Further, CPP estimation requires correct referencing (at the level of the foramen of Monro as opposed to the level of the heart) for MAP measurement to avoid CPP over-estimation and adverse patient outcomes. Evidence is emerging for the role of other monitors of cerebral well-being that enable the clinician to employ an individualized multimodality monitoring approach in patients with ABI, and these are briefly reviewed. While acknowledging difficulties in conducting robust prospective randomized studies in this area, such high-quality evidence for the utility of ICP/CPP-directed therapy in ABI is urgently required. So, too, is the wider adoption of multimodality neuromonitoring to guide optimal management of ICP and CPP, and a greater understanding of the underlying pathophysiology of the different forms of ABI and what exactly the different monitoring tools used actually represent.

  14. Estimation of the pore pressure distribution from three dimensional groundwater flow model at mine sites in Korea

    Science.gov (United States)

    Kang, Sangsoo; Jang, Myounghwan; Kim, Gyoungman; Kim, Donghui; Kim, Daehoon; Baek, Hwanjo

    2016-04-01

    Mining activities continually change the groundwater flow and associated pore pressure distributions within the rockmass around the mine openings or the open-pit bench during the operational periods. As the pore pressure distributions may substantially affect the mechanical behaviour or stability of the rockmass, it is important to monitor the variation of pore pressure incurred by mining operation. The pore pressure distributions within the rockmass can be derived using a two- or three-dimensional finite element groundwater flow model, adopted to simulate the groundwater flow. While the groundwater inflow at mines has generally been dealt with respect to the working environment, detailed case studies on the distribution of pore water pressure related to the stability analysis of mine openings have been relatively rare in Korea. Recently, however, as the health and safety problems are emerged for sustainable mining practice, these issues are of the major concerns for the mining industries. This study aims to establish a three dimensional groundwater flow model to estimate the pore pressure distributions in order to employ as an input parameter for numerical codes such as the FLAC 3D. Also, the groundwater flow simulated can be used for de-watering design at a mine site. The MINEDW code, a groundwater flow model code specifically developed to simulate the complicated hydro-geologic conditions related to mining, has mainly been used in this study. Based on the data collected from field surveys and literature reviews, a conceptual model was established and sensitivity analysis was performed.

  15. Estimating the parameters of a positive column of the halogen-containing glow discharge at moderate pressures

    Directory of Open Access Journals (Sweden)

    Alexander P. Golovitskii

    2015-03-01

    Full Text Available The methodical recommendations for estimating the plasma parameters of an electronegative glow discharge containing halogens at moderate pressures (up to 40 Torr with the use of simple analytic formulae and without numerical modeling are given. The initial data are easily measureable discharge parameters such as a discharge current, a voltage and a gas mixture pressure and composition as well. It is shown how one can easily consider such important plasma features as non-Maxwellian electron energy distribution function and halogen molecules dissociation by electron impact. As a result, such plasma parameters as the absolute degree of electronegativity, the value of border coordinate between ion–ion and electron–ion plasmas, and the forms of transversal profiles of electron and negative ion concentrations can be evaluated. The comparison of the results with the ones given by a global numerical model shows the suitability of said analytic approach to estimate plasma parameters of real discharges.

  16. Estimation of Joule heating effect on temperature and pressure distribution in electrokinetic-driven microchannel flows.

    Science.gov (United States)

    Chein, Reiyu; Yang, Yeong Chin; Lin, Yushan

    2006-02-01

    In this study we present simple analytical models that predict the temperature and pressure variations in electrokinetic-driven microchannel flow under the Joule heating effect. For temperature prediction, a simple model shows that the temperature is related to the Joule heating parameter, autothermal Joule heating parameter, external cooling parameter, Peclet number, and the channel length to channel hydraulic diameter ratio. The simple model overpredicted the thermally developed temperature compared with the full numerical simulation, but in good agreement with the experimental measurements. The factors that affect the external cooling parameters, such as the heat transfer coefficient, channel configuration, and channel material are also examined based on this simple model. Based on the mass conservation, a simple model is developed that predicts the pressure variations, including the temperature effect. An adverse pressure gradient is required to satisfy the mass conservation requirement. The temperature effect on the pressure gradient is via the temperature-dependent fluid viscosity and electroosmotic velocity.

  17. AIRUSE-LIFE +: estimation of natural source contributions to urban ambient air PM10 and PM2. 5 concentrations in southern Europe - implications to compliance with limit values

    Science.gov (United States)

    Diapouli, Evangelia; Manousakas, Manousos I.; Vratolis, Stergios; Vasilatou, Vasiliki; Pateraki, Stella; Bairachtari, Kyriaki A.; Querol, Xavier; Amato, Fulvio; Alastuey, Andrés; Karanasiou, Angeliki A.; Lucarelli, Franco; Nava, Silvia; Calzolai, Giulia; Gianelle, Vorne L.; Colombi, Cristina; Alves, Célia; Custódio, Danilo; Pio, Casimiro; Spyrou, Christos; Kallos, George B.; Eleftheriadis, Konstantinos

    2017-03-01

    The contribution of natural sources to ambient air particulate matter (PM) concentrations is often not considered; however, it may be significant for certain areas and during specific periods of the year. In the framework of the AIRUSE-LIFE+ project, state-of-the-art methods have been employed for assessing the contribution of major natural sources (African dust, sea salt and forest fires) to PM concentrations, in southern European urban areas. 24 h measurements of PM10 and PM2. 5 mass and chemical composition were performed over the course of a year in five cities: Porto, Barcelona, Milan, Florence and Athens. Net African dust and sea-salt concentrations were calculated based on the methodologies proposed by the EC (SEC 2011/208). The contribution of uncontrolled forest fires was calculated through receptor modelling. Sensitivity analysis with respect to the calculation of African dust was also performed, in order to identify major parameters affecting the estimated net dust concentrations. African dust contribution to PM concentrations was more pronounced in the eastern Mediterranean, with the mean annual relative contribution to PM10 decreasing from 21 % in Athens, to 5 % in Florence, and around 2 % in Milan, Barcelona and Porto. The respective contribution to PM2. 5 was calculated equal to 14 % in Athens and from 1.3 to 2.4 % in all other cities. High seasonal variability of contributions was observed, with dust transport events occurring at different periods in the western and eastern Mediterranean basin. Sea salt was mostly related to the coarse mode and also exhibited significant seasonal variability. Sea-salt concentrations were highest in Porto, with average relative contributions equal to 12.3 % for PM10. Contributions from uncontrolled forest fires were quantified only for Porto and were low on an annual basis (1.4 and 1.9 % to PM10 and PM2. 5, respectively); nevertheless, contributions were greatly increased during events, reaching 20 and 22 % of 24 h

  18. Correlation between Charge State of Insulating NaCl Surfaces and Ionic Mobility Induced by Water Adsorption: A Combined Ambient Pressure X-ray Photoelectron Spectroscopy and Scanning Force Microscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Verdaguer, Albert; Jose Segura, Juan; Fraxedas, Jordi; Bluhm, Hendrik; Salmeron, Miquel

    2008-09-03

    In situ ambient pressure X-ray photoelectron spectroscopy (APPES) and scanning force microscopy were used to characterize the surface discharge induced by water layers grown on (001) surfaces of sodium chloride single crystals. The APPES studies show that both kinetic energy (KE) and full width at half-maximum (FWHM) of the Na 2s and Cl 2p core level peaks, monitored as a function of relative humidity (RH), mimic surface conductivity curves measured using scanning force microscopy. The KE position and FWHM of the core level peaks therefore are directly related to the solvation and diffusion of ions at the NaCl(100) surface upon adsorption of water.

  19. Mechanism to synthesize a ‘moving optical mark’ at solid-ambient interface for the estimation of thermal diffusivity of solid

    Directory of Open Access Journals (Sweden)

    Settu Balachandar

    2016-01-01

    Full Text Available A novel mechanism is proposed, involving a novel interaction between solid-sample supporting unsteady heat flow with its ambient-humidity; invokes phase transformation of water-vapour molecule and synthesize a ‘moving optical-mark’ at sample-ambient-interface. Under tailored condition, optical-mark exhibits a characteristic macro-scale translatory motion governed by thermal diffusivity of solid. For various step-temperature inputs via cooling, position-dependent velocities of moving optical-mark are measured at a fixed distance. A new approach is proposed. ‘Product of velocity of optical-mark and distance’ versus ‘non-dimensional velocity’ is plotted. The slope reveals thermal diffusivity of solid at ambient-temperature; preliminary results obtained for Quartz-glass is closely matching with literature.

  20. Viscosity-adjusted estimation of pressure head and pump flow with quasi-pulsatile modulation of rotary blood pump for a total artificial heart.

    Science.gov (United States)

    Yurimoto, Terumi; Hara, Shintaro; Isoyama, Takashi; Saito, Itsuro; Ono, Toshiya; Abe, Yusuke

    2016-09-01

    Estimation of pressure and flow has been an important subject for developing implantable artificial hearts. To realize real-time viscosity-adjusted estimation of pressure head and pump flow for a total artificial heart, we propose the table estimation method with quasi-pulsatile modulation of rotary blood pump in which systolic high flow and diastolic low flow phased are generated. The table estimation method utilizes three kinds of tables: viscosity, pressure and flow tables. Viscosity is estimated from the characteristic that differential value in motor speed between systolic and diastolic phases varies depending on viscosity. Potential of this estimation method was investigated using mock circulation system. Glycerin solution diluted with salty water was used to adjust viscosity of fluid. In verification of this method using continuous flow data, fairly good estimation could be possible when differential pulse width modulation (PWM) value of the motor between systolic and diastolic phases was high. In estimation under quasi-pulsatile condition, inertia correction was provided and fairly good estimation was possible when the differential PWM value was high, which was not different from the verification results using continuous flow data. In the experiment of real-time estimation applying moving average method to the estimated viscosity, fair estimation could be possible when the differential PWM value was high, showing that real-time viscosity-adjusted estimation of pressure head and pump flow would be possible with this novel estimation method when the differential PWM value would be set high.

  1. Estimation of Pressure Index and Temperature Sensitivity Coefficient of Solid Rocket Propellants by Static Evaluation

    Directory of Open Access Journals (Sweden)

    Himanshu Shekhar

    2009-11-01

    Full Text Available Burning rate of a solid rocket propellant depends on pressure and temperature. Conventional strand burner and Crawford bomb test on propellant strands was conducted to assess these dependent parameters. However, behaviour of propellant in rocket motor is different from its behaviour in strand form. To overcome this anomaly, data from static evaluation of rocket motor was directly used for assessment of these burningrate controlling parameters. The conventional empirical power law (r=aoexp[p{T-To}]Pn was considered and a method was evolved for determination of pressure index (n and temperature sensitivity coefficient (p of burning rate for solid rocket propellants from static evaluation data. Effect of pressure index and temperature sensitivity coefficient on firing curve is also depicted. Propellant grain was fired in progressive mode to cover a very wide pressure range of 50 kg/cm2 to 250 kg/cm2 and propellant burning rate index was calculated to be 0.32 in the given pressure range. Propellant grain was fired at +35 °C and –20 °C temperatures and temperature sensitivity coefficient of burning rate was calculated to be 0.27 % per °C. Since both the values were evaluated from realised static evaluation curves, these are more realistic and accurate compared to data generated by conventional methods.Defence Science Journal, 2009, 59(6, pp.666-669, DOI:http://dx.doi.org/10.14429/dsj.59.1573

  2. Estimation of influence of myofascial release techniques on esophageal pressure in patients after total laryngectomy.

    Science.gov (United States)

    Marszałek, Sławomir; Zebryk-Stopa, Anna; Kraśny, Jacek; Obrebowski, Andrzej; Golusiński, Wojciech

    2009-08-01

    In patients after total laryngectomy, increased tension in myofascial neck and arm areas might be observed. Via fascial continuity it has an adverse impact on the superior esophageal constrictor forming the "mouth of the oesophagus", which hinders learning of esophageal speech. The aim is to assess the effect of manual myofascial release techniques on esophageal pressure in patients after total laryngectomy. Forty patients (12 F, 28 M), aged 43-75 (mean 56.8 years), 9 months to 13 years (average 3 years) after total laryngectomy, 35 patients (87.5%) after neck lymph node resection, 38 patients (95%) after radiotherapy. Esophageal pressure was assessed using modified Seeman's method. Manual myofascial release techniques were applied within head, neck, arms, upper trunk and upper limb areas. Wilcoxon and Shapiro-Wilk's test was used for the purpose of statistical analysis. Statistically significant decrease of the mean esophageal pressure was observed after the physiotherapy treatment. The average pressure among the examined patients decreased from 37.9 to 26.6 mmHg. The application of myofascial manual techniques decreases esophageal pressure, thus allowing patients to learn esophagus speech at a faster pace.

  3. Should we stop using the determination of central venous pressure as a way to estimate cardiac preload?

    Science.gov (United States)

    Muñoz Nañez, Manuel Felipe

    2012-01-01

    Introduction: The determination of the values of central venous pressure has long been used as a guideline for volumetric therapy in the resuscitation of the critical patient, but the performance of such parameter is currently being questioned as an effective measurement of cardiac preload. This has aroused great interest in the search for more accurate parameters to determine cardiac preload and a patient's blood volume. Goals and Methods: Based on literature currently available, we aim to discuss the performance of central venous pressure as an effective parameter to determine cardiac preload. Results and Conclusion: Estimating variables such as end-diastolic ventricular area and global end-diastolic volume have a better performance than central venous pressure in determining cardiac preload. Despite the best performance of these devices, central venous pressure is still considered in our setting as the most practical and most commonly available way to assess the patient's preload. Only dynamic variables such as pulse pressure change are superior in determining an individual's blood volume. PMID:24893061

  4. Evaluation of the scattered pressure due to infinite rigid cylinders, infinite elastic cylindrical shells, and rigid spheres in the presence of an ambient noise field

    Science.gov (United States)

    Honeycutt, Rebecca L.; Johnson, Steven J.

    1993-04-01

    The sound scattering due to an ambient noise field, approximated by a squared cosine function, is considered for infinite rigid and elastic cylinders and rigid spheres. For the cylinders, it is assumed that the acoustic wave front is parallel to the axis of the cylinder (informally incident). For this assumption, a closed form expression for the scattered sound field-to-incident ambient noise field (signal-to-noise) ratio is obtained not only for the cosine squared directivity, but for any arbitrary directivity which can be expressed in terms of a Fourier series. For the sphere, it is assumed that the noise is circumferentially symmetric which leads to a closed form expression for the signal-to-noise ratio due to a cosine squared directivity.

  5. Estimates of crystalline LiF thermal conductivity at high temperature and pressure by a Green-Kubo method

    Science.gov (United States)

    Jones, R. E.; Ward, D. K.

    2016-07-01

    Given the unique optical properties of LiF, it is often used as an observation window in high-temperature and -pressure experiments; hence, estimates of its transmission properties are necessary to interpret observations. Since direct measurements of the thermal conductivity of LiF at the appropriate conditions are difficult, we resort to molecular simulation methods. Using an empirical potential validated against ab initio phonon density of states, we estimate the thermal conductivity of LiF at high temperatures (1000-4000 K) and pressures (100-400 GPa) with the Green-Kubo method. We also compare these estimates to those derived directly from ab initio data. To ascertain the correct phase of LiF at these extreme conditions, we calculate the (relative) phase stability of the B1 and B2 structures using a quasiharmonic ab initio model of the free energy. We also estimate the thermal conductivity of LiF in an uniaxial loading state that emulates initial stages of compression in high-stress ramp loading experiments and show the degree of anisotropy induced in the conductivity due to deformation.

  6. Safety estimation of high-pressure hydraulic cylinder using FSI method

    Institute of Scientific and Technical Information of China (English)

    KIM J.H.; HAN S.M.; KIM Y.J.

    2016-01-01

    Hydraulic cylinder is a primary component of the hydraulic valve systems.The numerical study of hydraulic cylinder to evaluate the stress analysis,the life assessment and the performance of operation characteristics in hydraulic cylinder were described.The calculation of safety factor,fatigue life,piston chamber pressure,rod chamber pressure and the change of velocity of piston with flow time after the beginning of hydraulic cylinder were incorporated.Numerical analysis was performed using the commercial CFD code,ANSYS with unsteady,dynamic mesh model,two-way FSI (fluid-struc-ture interaction)method and k-εturbulent model.The internal pressure in hydraulic cylinder through stress analysis show higher than those of the yield strength.

  7. Estimation of Time Dependent Properties from Surface Pressure in Open Cavities

    Science.gov (United States)

    2008-02-01

    the aft wall when the shear layer enters the cavity. More recently, schlieren images of a cavity in transonic flow by Heller and Delfs (1996) have... Delfs , J., "Cavity Pressure Oscillations: The Generating Mechanisms Visualized," Journal of Sound and Vibration, Vol. 196, No. 2, 1996

  8. Magma-plumbing System of Asama Volcano after 2004 Eruption, Estimated from Vertical Deformation above the Presumed Pressure Sources

    Science.gov (United States)

    Kimata, F.

    2012-12-01

    Asama volcano is one of the active volcanoes in Japan, and it erupted on September 1, 2004. A shallow dike intrusion is estimated in the Takamine, 4 - 5 km west of the Asama crater from the ground deformation detected by GPS measurements (Aoki et al., 2005). Ground deformation observation close to the pressure source should clarify the depth and volume change of pressure sources. We establish the precise leveling routes ranging to Mt. Takamine above the presumed pressure source from Oiwake, at the southern foot of Asama volcano in May 2005.The precise levelings have practiced seven times for five years since May 2005 to June 2011. We calculated the vertical deformation for six-months or two-years between leveling epochs. Generally, deformations detected by the precise leveling are small of 10 mm. Deformations detected in the periods of May 2005 - Nov.2005. - May 2006 - May 2009 - June 2010 - June 2011, are grouping two patterns. One is definite subsidence, and another is slight uplift. Murakami (2005) discusses the line length changes between two GPS sites of Tsumagoi and Tobu, and he shows that the extension of line length just before the eruption in 2004 and 2009 and contraction between the eruption. Slight uplifts in the periods of May 2005 - May 2006 are corresponding to the period observed the extension, and subsidence in the periods of May 2006 - May 2007, May 2009 - June 2010, and June 2010 - June 2011. Two pressures sources are estimated from the ground deformation detected by precise leveling. One is a deeper spherical deflation source in the 6 km BSL depth beneath the mountainside, and another is the shallow dike intrusion beneath Mt. Takamine. A pressure source model was previously estimated from the leveling data for last 100 years (Murase et al., 2007), and it is suggestive a dominant source of the Asama volcano. They suggest a slight inflation after 1960, however our results show the deflation of -6.6 km3/6yr in the deeper sources for five years after

  9. Determinação de volumes e pressões de balonetes de tubos traqueais insuflados com ar ambiente ou óxido nitroso Determinación de volúmenes y presiones de balones de tubos traqueales insuflados con aire ambiente u óxido nitroso Volume and pressure of tracheal tube cuffs filled with air or nitrous oxide

    Directory of Open Access Journals (Sweden)

    Ernesto Leonardo Cárpio Peña

    2004-06-01

    balanceada con entubación orotraqueal. El balón fue insuflado conforme criterios clínicos. Las medidas de base fueron realizadas después de 15 minutos del inicio de la anestesia con un manómetro aneróide calibrado en cm de H2O y dieron los valores iniciales de presión y volumen. Los pacientes fueron divididos en dos grupos: balón reinsuflado con aire ambiente, grupo A, o con óxido nitroso, grupo B. Las medidas de presión fueron obtenidas en intervalos hasta la primera hora y los resultados comparados. RESULTADOS: Los grupos se mostraron comparables para edad y sexo. En ambos grupos los valores basales medios para presión fueron próximos de 40 cmH2O con 8 ml de volumen. En el grupo con aire ambiente, las presiones aumentaron hasta 36 cmH2O en una hora. En el grupo de balón insuflado con N2O, las presiones cayeron abajo de 20 cmH2O entre 20 y 30 minutos de anestesia. CONCLUSIONES: El uso de N2O a 100% para insuflación del balón de sonda traqueal no constituye método seguro, acarreando progresiva pérdida de la capacidad de vedación. El uso de aire ambiente promueve aumento de volumen y de presión en el balón, aumentando la posibilidad de lesión de la mucosa traqueal.BACKGROUND AND OBJECTIVES: Tracheal tube cuff pressure against tracheal wall should to prevent air leaked or pulmonary aspiration, allowing adequate capillary blood flow. This study aimed at determining pressure variations of tracheal tube cuffs filled with air or 100% nitrous oxide. METHODS: Participated in this study 30 patients submitted to balanced general anesthesia with tracheal intubation. Cuff was inflated according to clinical criteria. The intracuff pressure measurements were undertaken after 15 minutes of anesthesia by means of an aneroid manometer gaged in cm of H2O and have provided initial pressure and volume values. The patients was allocated in two groups: cuff inflated with air, group A, and with nitrous oxide, group B. Measurements were recorded during one hour and results were

  10. Estimation of pressure-particle velocity impedance measurement uncertainty using the Monte Carlo method.

    Science.gov (United States)

    Brandão, Eric; Flesch, Rodolfo C C; Lenzi, Arcanjo; Flesch, Carlos A

    2011-07-01

    The pressure-particle velocity (PU) impedance measurement technique is an experimental method used to measure the surface impedance and the absorption coefficient of acoustic samples in situ or under free-field conditions. In this paper, the measurement uncertainty of the the absorption coefficient determined using the PU technique is explored applying the Monte Carlo method. It is shown that because of the uncertainty, it is particularly difficult to measure samples with low absorption and that difficulties associated with the localization of the acoustic centers of the sound source and the PU sensor affect the quality of the measurement roughly to the same extent as the errors in the transfer function between pressure and particle velocity do.

  11. Cuffless Blood Pressure Estimation with Photoplethysmograph Signal by Classifying on Account of Cardiovascular Characteristics of Old Aged Patients

    Science.gov (United States)

    Suzuki, Satomi; Oguri, Koji

    Blood Pressure (BP) is a very important factor for monitoring the cardiovascular condition. In general, non-invasive BP measurements need a cuff. However, such measurement techniques can hardly monitor BP continuously. Recently it has gotten easier to measure biological signals daily because sensor technologies have well-developed, and because of availability of many kinds of miniaturized measurement instruments consuming less power. This study suggests a method of estimating Systolic Blood Pressure (SBP) with a wearable sensor instead of a cuff. In particular, our study depends on only one pulse wave signal detected by a Photoplethysmograph (PPG) sensor since the PPG sensor is very small. Moreover, the human subject just wears the sensor on the surface of the body to measure the signal. Cardiovascular peculiarities keep changing as people get older. Additionally, the peculiarities vary among individuals according to the advanced rate of arteriosclerosis. Hence, it is necessary for estimating the SBP to divide the data into several classes, by parameters that relate to individual cardiovascular peculiarities. In this study, the regression equation of SBP was calculated from individual information and from features of the PPG signal in each class. As a result, the estimation accuracy was improved. This technique would make cuffless SBP monitoring become more convenient and helpful as only one device is required for monitoring, which is smaller than traditional measurements.

  12. ESTIMATES OF THE ERROR OF EXPERIMENTAL DATA AT STUDIES OF DENSITY AND THE SATURATED VAPOR PRESSURE (SVP PETROLEUM PRODUCTS

    Directory of Open Access Journals (Sweden)

    Kharchenko P. M.

    2015-10-01

    Full Text Available At calculations, we have used the next assumptions: 1. Not excluded systematic errors distributed with equal probability; 2. Random errors are normally distributed; 3. Total error is the composition of not excluded systematic and random errors. In calculating of measurement error of pressure, we proceeded from working formula. The confidence interval of each variable less than instrumental error, therefore, to characterize the total error of the measured value P, we use the instrumental errors of all variables. In estimating of temperature measurement error was consider the systematic and random error. To estimate random error we used measurement data of the specific volume of water on six isotherms. Obtained values were compared with published data. As an approximate estimate of the random error of our experimental data, we can take it as a total for all the isotherms of the specific volume in comparison with the published data. For studied fractions confidence limit of total error of measurement results located in the range of 0,03 ч 0,1%. At temperatures close to the critical increasing influence of errors of reference and the error associated with the introduction of corrections on the thermal expansion of the piezometer. In the two-phase area confidence limit of total error increases and located between 0,08 ч 0,15%. This is due to the sharp increase in this area of reference error of pressure and error in determining to the weight of the substance in the piezometer

  13. Noninvasive and quantitative intracranial pressure estimation using ultrasonographic measurement of optic nerve sheath diameter

    Science.gov (United States)

    Wang, Li-juan; Yao, Yan; Feng, Liang-shu; Wang, Yu-zhi; Zheng, Nan-nan; Feng, Jia-chun; Xing, Ying-qi

    2017-01-01

    We aimed to quantitatively assess intracranial pressure (ICP) using optic nerve sheath diameter (ONSD) measurements. We recruited 316 neurology patients in whom ultrasonographic ONSD was measured before lumbar puncture. They were randomly divided into a modeling and a test group at a ratio of 7:3. In the modeling group, we conducted univariate and multivariate analyses to assess associations between ICP and ONSD, age, sex, BMI, mean arterial blood pressure, diastolic blood pressure. We derived the mathematical function “Xing & Wang” from the modelling group to predict ICP and evaluated the function in the test group. In the modeling group, ICP was strongly correlated with ONSD (r = 0.758, p Watson value = 1.94). In the test group, a significant correlation was found between the observed and predicted ICP (r = 0.76, p < 0.001). Bland-Altman analysis yielded a mean difference between measurements of −0.07 ± 41.55 mmH2O. The intraclass correlation coefficient and its 95%CIs for noninvasive ICP assessments using our prediction model was 0.86 (0.79–0.90). Ultrasonographic ONSD measurements provide a potential noninvasive method to quantify ICP that can be conducted at the bedside. PMID:28169341

  14. The effect of radiation pressure on virial black hole mass estimates and the case of Narrow Line Seyfert 1 galaxies

    CERN Document Server

    Marconi, Alessandro; Maiolino, Roberto; Nagao, Tohru; Pastorini, Guia; Pietrini, Paola; Robinson, Andrew; Torricelli, Guidetta

    2008-01-01

    We consider the effect of radiation pressure from ionizing photons on black hole (BH) mass estimates based on the application of the virial theorem to broad emission lines in AGN spectra. BH masses based only on the virial product V^2R and neglecting the effect of radiation pressure can be severely underestimated especially in objects close to the Eddington limit. We provide an empirical calibration of the correction for radiation pressure and we show that it is consistent with a simple physical model in which BLR clouds are optically thick to ionizing radiation and have average column densities of NH~10^23 cm^-2. This value is remarkably similar to what is required in standard BLR photoionization models to explain observed spectra. With the inclusion of radiation pressure the discrepancy between virial BH masses based on single epoch spectra and on reverberation mapping data drops from 0.4 to 0.2 dex rms. The use of single epoch observations as surrogates of reverberation mapping campaigns can thus provide m...

  15. Using pressure and volumetric approaches to estimate CO2 storage capacity in deep saline aquifers

    OpenAIRE

    Thibeau, S.; Bachu, S.; Birkholzer, J.; Holloway, S; Neele, F.P.; Zou, Q

    2014-01-01

    Various approaches are used to evaluate the capacity of saline aquifers to store CO2, resulting in a wide range of capacity estimates for a given aquifer. The two approaches most used are the volumetric “open aquifer” and “closed aquifer” approaches. We present four full-scale aquifer cases, where CO2 storage capacity is evaluated both volumetrically (with “open” and/or “closed” approaches) and through flow modeling. These examples show that the “open aquifer” CO2 storage capacity estimation ...

  16. Impact of Spatial Resolution on Wind Field Derived Estimates of Air Pressure Depression in the Hurricane Eye

    Directory of Open Access Journals (Sweden)

    Linwood Jones

    2010-03-01

    Full Text Available Measurements of the near surface horizontal wind field in a hurricane with spatial resolution of order 1–10 km are possible using airborne microwave radiometer imagers. An assessment is made of the information content of the measured winds as a function of the spatial resolution of the imager. An existing algorithm is used which estimates the maximum surface air pressure depression in the hurricane eye from the maximum wind speed. High resolution numerical model wind fields from Hurricane Frances 2004 are convolved with various HIRAD antenna spatial filters to observe the impact of the antenna design on the central pressure depression in the eye that can be deduced from it.

  17. Using pressure and volumetric approaches to estimate CO2 storage capacity in deep saline aquifers

    NARCIS (Netherlands)

    Thibeau, S.; Bachu, S.; Birkholzer, J.; Holloway, S.; Neele, F.P.; Zou, Q.

    2014-01-01

    Various approaches are used to evaluate the capacity of saline aquifers to store CO2, resulting in a wide range of capacity estimates for a given aquifer. The two approaches most used are the volumetric “open aquifer” and “closed aquifer” approaches. We present four full-scale aquifer cases, where C

  18. A Remote Sensing Method for Estimating Surface Air Temperature and Surface Vapor Pressure on a Regional Scale

    Directory of Open Access Journals (Sweden)

    Renhua Zhang

    2015-05-01

    Full Text Available This paper presents a method of estimating regional distributions of surface air temperature (Ta and surface vapor pressure (ea, which uses remotely-sensed data and meteorological data as its inputs. The method takes into account the effects of both local driving force and horizontal advection on Ta and ea. Good correlation coefficients (R2 and root mean square error (RMSE between the measurements of Ta/ea at weather stations and Ta/ea estimates were obtained; with R2 of 0.77, 0.82 and 0.80 and RMSE of 0.42K, 0.35K and 0.20K for Ta and with R2 of 0.85, 0.88, 0.88 and RMSE of 0.24hpa, 0.35hpa and 0.16hpa for ea, respectively, for the three-day results. This result is much better than that estimated from the inverse distance weighted method (IDW. The performance of Ta/ea estimates at Dongping Lake illustrated that the method proposed in the paper also has good accuracy for a heterogeneous surface. The absolute biases of Ta and ea estimates at Dongping Lake from the proposed method are less than 0.5Kand 0.7hpa, respectively, while the absolute biases of them from the IDW method are more than 2K and 3hpa, respectively. Sensitivity analysis suggests that the Ta estimation method presented in the paper is most sensitive to surface temperature and that the ea estimation method is most sensitive to available energy.

  19. Non-invasive estimation and control of inlet pressure in an implantable rotary blood pump for heart failure patients.

    Science.gov (United States)

    Alomari, A H; Savkin, A V; Ayre, P J; Lim, E; Mason, D G; Salamonsen, R F; Fraser, J F; Lovell, N H

    2011-08-01

    We propose a dynamical model for mean inlet pressure estimation in an implantable rotary blood pump during the diastolic period. Non-invasive measurements of pump impeller rotational speed (ω), motor power (P), and pulse width modulation signal acquired from the pump controller were used as inputs to the model. The model was validated over a wide range of speed ramp studies, including (i) healthy (C1), variations in (ii) heart contractility (C2); (iii) afterload (C2, C3, C4), and (iv) preload (C5, C6, C7). Linear regression analysis between estimated and extracted mean inlet pressure obtained from in vivo animal data (greyhound dogs, N = 3) resulted in a highly significant correlation coefficients (R(2) = 0.957, 0.961, 0.958, 0.963, 0.940, 0.946, and 0.959) and mean absolute errors of (e = 1.604, 2.688, 3.667, 3.990, 2.791, 3.215, and 3.225 mmHg) during C1, C2, C3, C4, C5, C6, and C7, respectively. The proposed model was also used to design a controller to regulate mean diastolic pump inlet pressure using non-invasively measured ω and P. In the presence of model uncertainty, the controller was able to track and settle to the desired input within a finite number of sampling periods and minimal error (0.92 mmHg). The model developed herein will play a crucial role in developing a robust control system of the pump that detects and thus avoids undesired pumping states by regulating the inlet pressure within a predefined physiologically realistic limit.

  20. Online estimation of respiratory mechanics in non-invasive pressure support ventilation: a bench model study.

    Science.gov (United States)

    Mulqueeny, Qestra; Tassaux, Didier; Vignaux, Laurence; Jolliet, Philippe; Schindhelm, Klaus; Redmond, Stephen; Lovell, Nigel H

    2010-01-01

    An online algorithm for determining respiratory mechanics in patients using non-invasive ventilation (NIV) in pressure support mode was developed and embedded in a ventilator system. Based on multiple linear regression (MLR) of respiratory data, the algorithm was tested on a patient bench model under conditions with and without leak and simulating a variety of mechanics. Bland-Altman analysis indicates reliable measures of compliance across the clinical range of interest (± 11-18% limits of agreement). Resistance measures showed large quantitative errors (30-50%), however, it was still possible to qualitatively distinguish between normal and obstructive resistances. This outcome provides clinically significant information for ventilator titration and patient management.

  1. Estimating the Error in Statistical HAMR Object Populations Resulting from Simplified Radiation Pressure Modeling

    Science.gov (United States)

    Flegel, S.; Vörsmann, P.; Wiedemann, C.; Kebschull, C.; Braun, V.; Möckel, M.; Gelhaus, J.; Krag, H.; Klinkrad, H.

    2012-09-01

    The high-area-to-mass ratio (HAMR) object population in ESA's MASTER-2009 software (Meteoroid and Space Debris Terrestrial Environment Reference) is dominated by Multi-Layer Insulation debris at large sizes. The underlying model employs two independent mechanisms whereby Multi-Layer Insulation debris is created. These mechanisms are fragmentation events on the one hand and a deterioration process leading to the continuous release of larger objects on the other hand. All debris source models used to create the MASTER debris population rely on a semi-analytical propagator to model the major secular and long periodic orbit perturbations. The orbit parameters of HAMR objects are highly susceptive to radiation pressure effects which can result in fast secular and periodic changes for area-to-mass ratios above about 1 square meter per kilogram. The implementation of radiation pressure in this propagator is limited to the effects of solar irradiation on a spherical object and using a cylindrical Earth shadow. The current paper discusses the applicability of such a simplified theory to large statistical HAMR object populations where the main objective is not to predict the exact future location of a single object but rather to give a correct representation of the overall distribution of all HAMR objects. The basis for the current study is given by a numerical propagator which is supported by published observation results. Initially, the effects of object orientation, Earth albedo and thermal radiation on the orbit evolution are discussed. Results from published observations and simulation results give insight into the validity of the implemented model. Fundamental differences between the orbit prediction of this refined numerical propagator and the semi-analytical propagator are looked at with a view towards large statistical populations. To this end, a plausible, statistical, population of HAMR objects is propagated over an extended time period using both propagation

  2. Pressure estimation from PIV like data of compressible flows by boundary driven adjoint data assimilation

    Science.gov (United States)

    Lemke, Mathias; Reiss, Julius; Sesterhenn, Jörn

    2016-06-01

    Particle image velocimetry (PIV) is one of the major tools to measure velocity fields in experiments. However, other flow properties like density or pressure are often of vital interest, but usually cannot be measured non-intrusively. There are many approaches to overcome this problem, but none is fully satisfactory. Here the computational method of an adjoint based data assimilation for this purpose is discussed. A numerical simulation of a flow is adapted to given velocity data. After successful adaption, previously unknown quantities can be taken from the - necessarily complete - simulation data. The main focus of this work is the efficient implementation of this approach by boundary driven optimisation. Synthetic test cases are presented to allow an assessment of the method.

  3. Sensitivity of CO2 migration estimation on reservoir temperature and pressure uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Preston; Doughty, Christine

    2008-11-01

    The density and viscosity of supercritical CO{sub 2} are sensitive to pressure and temperature (PT) while the viscosity of brine is sensitive primarily to temperature. Oil field PT data in the vicinity of WESTCARB's Phase III injection pilot test site in the southern San Joaquin Valley, California, show a range of PT values, indicating either PT uncertainty or variability. Numerical simulation results across the range of likely PT indicate brine viscosity variation causes virtually no difference in plume evolution and final size, but CO{sub 2} density variation causes a large difference. Relative ultimate plume size is almost directly proportional to the relative difference in brine and CO{sub 2} density (buoyancy flow). The majority of the difference in plume size occurs during and shortly after the cessation of injection.

  4. A RETROSPECTIVE STUDY OF THE IMPACT OF MEAN ARTERIAL PRESSURE ON ESTIMATED BLOOD LOSS DURING ENDOSCOPIC SINUS SURGERY

    Directory of Open Access Journals (Sweden)

    George W Williams

    2014-10-01

    Full Text Available The current practice of lowering mean arterial pressure (MAP during endoscopic sinus surgery (ESS is common, but unproven with regard to peer reviewed literature. The controlled hypotension induced is aimed for improved surgical field and lower the blood loss. Lower mean arterial pressures especially for prolonged surgeries may result in end organ hypoperfusion. The authors reviewed all patients who underwent outpatient endoscopic sinus surgery for the diagnosis of chronic sinusitis from January 1, 2012 to December 31, 2012 at Memorial Hermann Hospital – Texas Medical Centre. We individually reviewed case sheets of every patient and documented blood loss as recorded on the anaesthesia record or in the surgical procedure note, among other variables. A total of 326 patients were included in this study. The median estimated blood loss (EBL was found to be 50 ml. The multivariate regression analysis between these three groups showed that EBL was higher in MAP 75 group. The average of EBL in MAP75 group and the average of EBL in MAP 65-70 group is 42% higher than that in MAP>75 group when other variables were fixed. Hence we found the trend toward higher blood loss with lower MAP. The authors conclude that lower MAP does not result in lower EBL in endoscopic sinus surgery. Furthermore, increases in BMI and crystalloid administered during an aesthetic management of these cases correlates with increased estimate blood loss.

  5. Yield loss prediction models based on early estimation of weed pressure

    DEFF Research Database (Denmark)

    Asif, Ali; Streibig, Jens Carl; Andreasen, Christian

    2013-01-01

    Weed control thresholds have been used to reduce costs and avoid unacceptable yield loss. Estimation of weed infestation has often been based on counts of weed plants per unit area or measurement of their relative leaf area index. Various linear, hyperbolic, and sigmoidal regression models have...... thresholds are more relevant for site-specific weed management, because weeds are unevenly distributed in fields. Precision of prediction of yield loss is influenced by various factors such as locations, yield potential at the site, variation in competitive ability of mix stands of weed species and emergence...

  6. Estimation of dynamic properties of attractors observed in hollow copper electrode atmospheric pressure arc plasma system

    Indian Academy of Sciences (India)

    S Ghorul; S N Sahasrabudhe; P S S Murthy; A K Das; N Venkatramani

    2002-07-01

    Understanding of the basic nature of arc root fluctuation is still one of the unsolved problems in thermal arc plasma physics. It has direct impact on myriads of thermal plasma applications being implemented at present. Recently, chaotic nature of arc root behavior has been reported through the analysis of voltages, acoustic and optical signals which are generated from a hollow copper electrode arc plasma torch. In this paper we present details of computations involved in the estimation process of various dynamic properties and show how they reflect chaotic behavior of arc root in the system.

  7. Estimation of Nonconservative Aerodynamic Pressure Leading to Flutter of Spinning Disks

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig; Raman, A; Mote Jr., C.D.

    2001-01-01

    An experimental method for predicting the onset of #utter of a disk spinning in a #uid medium is proposed. The method is based on a description of the aerodynamic loading on the disk as a distributed viscous damping force rotating relative to the disk. This model can arise from two aeroelastic...... theories described herein. It is shown analytically and experimentally that the few parameters of this model may be extracted from frequency response functions of the spinning disk. Parameters for a steel disk in air (with a near vacuum experiment as reference) are estimated at increasing rotation speeds...

  8. Influence of center of pressure estimation errors on 3D inverse dynamics solutions during gait at different velocities.

    Science.gov (United States)

    Camargo-Junior, Franklin; Ackermann, Marko; Loss, Jefferson F; Sacco, Isabel C N

    2013-12-01

    The aim of this study was to investigate the effect of errors in the location of the center of pressure (5 and 10 mm) on lower limb joint moment uncertainties at different gait velocities (1.0, 1.5, and 2.0 m/s). Our hypotheses were that the absolute joint moment uncertainties would be gradually reduced from distal to proximal joints and from higher to lower velocities. Joint moments of five healthy young adults were calculated by inverse dynamics using the bottom-up approach, depending on which estimate the uncertainty propagated. Results indicated that there is a linear relationship between errors in center of pressure and joint moment uncertainties. The absolute moment peak uncertainties expressed on the anatomic reference frames decreased from distal to proximal joints, confirming our first hypothesis, except for the abduction moments. There was an increase in moment uncertainty (up to 0.04 N m/kg for the 10 mm error in the center of pressure) from the lower to higher gait velocity, confirming our second hypothesis, although, once again, not for hip or knee abduction. Finally, depending on the plane of movement and the joint, relative uncertainties experienced variation (between 5 and 31%), and the knee joint moments were the most affected.

  9. Modelamiento del Ambiente Térmico y Aéreo de un Galpón de Presión Negativa Tipo Túnel para Pollitos / Modeling of the Thermal Environments in Shed Negative Pressure Tunnel Type of Chicks

    Directory of Open Access Journals (Sweden)

    Robinson Osorio Hernández

    2013-12-01

    Full Text Available La optimización de los procesos productivos tiene granimportancia en el mundo actual debido al continuo desarrollo y avance. Con la finalidad de evaluar el desempeño productivo en el sector avícola, se hace necesaria la adecuación del ambiente interno de las instalaciones avícolas con técnicas que atiendan las exigencias de confort térmico con mayor eficiencia energética. En este trabajo, se evaluó el ambiente térmico interno de un galpón de presión negativa tipo túnel durante la primera fase de crecimiento de pollos de engorde. La evaluación de comportamiento térmico en este período fue realizada utilizando la dinámica de fluidos computacionales (CFD. El modelo computacional demostró ser una herramienta eficaz para el entendimiento y mejora de diseños bioclimáticos de ambientes internos de galpones avícolas. / The optimization of production processes hasgreat importance in the world due to the development andadvancement. In order to evaluate the productive performance in poultry production, it becomes necessary the indoor environmental adequacy of the poultry buildings by technologies that attend the requirements of thermal comfort with major energy efficiency. This study evaluated the thermal environment of a domestic shed of negative pressure tunnel type, during the first growth phase of broilers. The evaluation of the thermal behavior model during this period was made using the computational fluid dynamics (CFD. The computational model proved to be an effective tool forunderstanding and improving of bioclimatic designs of indoorenvironments to create this kind of sheds.

  10. A Study of The Elongational Flow of Dilute Polymer Solutions : Estimation of The Elongational Stresses by Utilizing Pressure Drops with Orifice Flows

    OpenAIRE

    福冨, 清; 長谷川, 富市; Fukutomi, Kiyoshi; Hasegawa, Tomiichi

    1988-01-01

    By assuming a uniformly converging radial flow on the upstream side of an orifice and integrating the equation of motion, an expression was derived to estimate elongational stresses for dilute polymer solutions at the orifice exit from pressure drops between the upstream and downstream of the orifice. The expression shown that the dilute polymer solutions usually give lower values of pressure drop than the solvent (water) does. An experiment was carried out to obtain the pressure drops for th...

  11. Effect of injection pressure and ambient pressure on spray characteristics of pine oil-diesel blends%喷射压力及环境背压对松油-柴油混合燃料喷雾特性的影响

    Institute of Scientific and Technical Information of China (English)

    黄豪中; 史程; 张鹏; 王庆新; 刘庆生; 班智博

    2016-01-01

    为探究柴油/松油混合燃料的喷雾特性,基于高压可视化容弹试验台,通过高速摄影技术对掺松油的柴油混合燃料的喷雾过程进行试验研究,分析了喷射压力、背压和燃料物性的改变对喷雾宏观参数的影响。结果表明:混合燃料的喷雾贯穿距离先呈现一定程度的线性增长,然后增长幅度逐渐变小,喷雾锥角呈先减小再保持在一个相对稳定的数值趋势,但全程锥角变化不大;喷射压力从90 MPa升高至150 MPa,混合燃料的喷雾锥角和贯穿距离的平均增幅分别为9.2%和15%;背压从3 MPa增加到5 MPa,混合燃料的平均喷雾锥角增幅约2.6°,而贯穿距离降低11 mm左右,说明背压的改变对喷雾特性影响显著;将广安公式适当地修正可与混合燃料的贯穿距离相互吻合;向柴油中掺混一定比例的松油后,燃料的黏度降低,会引起喷雾锥角、贯穿距离和油束面积均小幅增大,增强燃料的油气混合。试验研究有助于改善柴油的雾化质量,可为柴油机代用燃料的筛选提供参考。%The fuel spray performance and atomization quality played a fundamental role in promoting the level of combustion efficiency and exhaust emissions in internal combustion engines. In order to achieve better atomizing mode of diesel, we conducted experiments to study the spray characteristics of diesel blending pine oil. A diesel/pine oil spray trial platform was constructed to carry out a visual constant volume chamber and the high-pressure common rail test bench. The high-speed photograph technique was applied to systematically investigate the spray process of blended fuel. The study was conducted under the pine oil blending ratios of with 0, 20%, 40% and 50%, respectively. Then, the influences of injection pressure, ambient pressure and fuel property on macroscopic spray parameters (including spray cone angle, spray penetration distance and fuel flow area

  12. Effects of living at two ambient temperatures on 24-h blood pressure and neuroendocrine function among obese and non-obese humans: a pilot study

    Science.gov (United States)

    Kanikowska, Dominika; Sato, Maki; Iwase, Satoshi; Shimizu, Yuuki; Nishimura, Naoki; Inukai, Yoko; Sugenoya, Junichi

    2013-05-01

    The effects of environmental temperature on blood pressure and hormones in obese subjects in Japan were compared in two seasons: summer vs winter. Five obese (BMI, 32 ± 5 kg/m2) and five non-obese (BMI, 23 ±3 kg/m2) men participated in this experiment at latitude 35°10' N and longitude 136°57.9' E. The average environmental temperature was 29 ± 1 °C in summer and 3 ± 1 °C in winter. Blood samples were analyzed for leptin, ghrelin, catecholamines, thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), total cholesterol, triglycerides, insulin and glucose. Blood pressure was measured over the course of 24 h in summer and winter. A Japanese version of the Profile of Mood States (POMS) questionnaire was also administered each season. Systolic and diastolic blood pressures in obese men were significantly higher in winter (lower environmental temperatures) than in summer (higher environmental temperatures). Noradrenaline and dopamine concentrations were also significantly higher at lower environmental temperatures in obese subjects, but ghrelin, TSH, fT3, fT4, insulin and glucose were not significantly different in summer and winter between obese and non-obese subjects. Leptin, total cholesterol and triglyceride concentrations were significantly higher in winter in obese than non-obese men. Results from the POMS questionnaire showed a significant rise in Confusion at lower environmental temperatures (winter) in obese subjects. In this pilot study, increased blood pressure may have been due to increased secretion of noradrenaline in obese men in winter, and the results suggest that blood pressure control in obese men is particularly important in winter.

  13. Superconductivity and structural characteristics of ceramic Pr{sub 2}Ba{sub 4}Cu{sub 7}O{sub 15-{delta}} prepared by ambient pressure synthesis using citrate pyrolysis method

    Energy Technology Data Exchange (ETDEWEB)

    Hagiwara, M. [Department of Comprehensive Sciences, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan)], E-mail: hag@kit.ac.jp; Shima, T.; Tanaka, S.; Nishio, K.; Isshiki, T. [Department of Comprehensive Sciences, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan); Saito, T.; Koyama, K. [University of Tokushima, Tokushima 770-8502 (Japan)

    2007-10-01

    Sintered material of Pr{sub 2}Ba{sub 4}Cu{sub 7}O{sub 15-{delta}} (Pr247) was synthesized at ambient pressure condition by using citrate pyrolysis precursor method, and the superconductivity caused by oxygen reduction treatment has been confirmingly observed and examined. By resistivity and magnetization experiments, it has been found that the critical temperature T{sub c} of the reduced samples could reach about 10 K higher than previously reported data for pure Pr247. Besides, from TEM observations, the present material was found to be heterogeneous system containing Pr247, Pr124 and novel stacking structure phases rich in CuO single chains. These results have suggested that oxygen-reduction at such region rich in the CuO single chains may affect the superconductivity of the adjacent crystal region containing CuO double chains, and might enhance the superconductive critical temperature.

  14. The influence of methanol on the chemical state of PtRu anodes in a high-temperature direct methanol fuel cell studied in situ by synchrotron-based near-ambient pressure x-ray photoelectron spectroscopy

    Science.gov (United States)

    Saveleva, Viktoriia A.; Daletou, Maria K.; Savinova, Elena R.

    2017-01-01

    Synchrotron radiation-based near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) has recently become a powerful tool for the investigation of interfacial phenomena in electrochemical power sources such as batteries and fuel cells. Here we present an in situ NAP-XPS study of the anode of a high-temperature direct methanol fuel cell with a phosphoric acid-doped hydrocarbon membrane, which reveals an enhanced flooding of the Pt3Ru anode with phosphoric acid in the presence of methanol. An analysis of the electrode surface composition depending on the cell voltage and on the presence of methanol reveals the strong influence of the latter on the extent of Pt oxidation and on the transformation of Ru into Ru (IV) hydroxide.

  15. Novel empirical correlations for estimation of bubble point pressure, saturated viscosity and gas solubility of crude oils

    Institute of Scientific and Technical Information of China (English)

    Ehsan Khamehchi; Fariborz Rashidi; Hanieh Rasouli; Amir Ebrahi-mian

    2009-01-01

    Knowledge of petroleum fluid properties is crucial for the study of reservoirs and their development. Estimation of reserves in an oil reservoir or determination of its performance and economics requires a good knowledge of the fluid physical properties. Bubble point pressure, gas solubility and viscosity of oils are the most important parameters in use for petroleum and chemical engineers. In this study a simple-to-use, straight-forward mathematical model was correlated on a set of 94 crude oil data. Three correlations were achieved based on an exponential regression, which were different from conventional empirical correlations, and were evaluated against 12 laboratory data other than those used for the regression. It is concluded that the new exponential equation is of higher precision and accuracy than the conventional correlations and is a more convenient mathematical formulation.

  16. Estimation of minimum miscibility pressure (MMP) of CO2 and liquid n-alkane systems using an improved MRI technique.

    Science.gov (United States)

    Liu, Yu; Jiang, Lanlan; Song, Yongchen; Zhao, Yuechao; Zhang, Yi; Wang, Dayong

    2016-02-01

    Minimum miscible pressure (MMP) of gas and oil system is a key parameter for the injection system design of CO2 miscible flooding. Some industrial standard approaches such as the experiment using a rising bubble apparatus (RBA), the slim tube tests (STT), the pressure-density diagram (PDD), etc. have been applied for decades to determine the MMP of gas and oil. Some theoretical or experiential calculations of the MMP were also applied to the gas-oil miscible system. In the present work, an improved technique based on our previous research for the estimation of the MMP by using magnetic resonance imaging (MRI) was proposed. This technique was then applied to the CO2 and n-alkane binary and ternary systems to observe the mixing procedure and to study the miscibility. MRI signal intensities, which represent the proton concentration of n-alkane in both the hydrocarbon rich phase and the CO2 rich phase, were plotted as a reference for determining the MMP. The accuracy of the MMP obtained by using this improved technique was enhanced comparing with the data obtained from our previous works. The results also show good agreement with other established techniques (such as the STT) in previous published works. It demonstrates increases of MMPs as the temperature rise from 20 °C to 37.8 °C. The MMPs of CO2 and n-alkane systems are also found to be proportional to the carbon number in the range of C10 to C14.

  17. Efficient catalytic interconversion between NADH and NAD+ accompanied by generation and consumption of hydrogen with a water-soluble iridium complex at ambient pressure and temperature.

    Science.gov (United States)

    Maenaka, Yuta; Suenobu, Tomoyoshi; Fukuzumi, Shunichi

    2012-01-11

    Regioselective hydrogenation of the oxidized form of β-nicotinamide adenine dinucleotide (NAD(+)) to the reduced form (NADH) with hydrogen (H(2)) has successfully been achieved in the presence of a catalytic amount of a [C,N] cyclometalated organoiridium complex [Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))benzoic acid-κC(3))(H(2)O)](2) SO(4) [1](2)·SO(4) under an atmospheric pressure of H(2) at room temperature in weakly basic water. The structure of the corresponding benzoate complex Ir(III)(Cp*)(4-(1H-pyrazol-1-yl-κN(2))-benzoate-κC(3))(H(2)O) 2 has been revealed by X-ray single-crystal structure analysis. The corresponding iridium hydride complex formed under an atmospheric pressure of H(2) undergoes the 1,4-selective hydrogenation of NAD(+) to form 1,4-NADH. On the other hand, in weakly acidic water the complex 1 was found to catalyze the hydrogen evolution from NADH to produce NAD(+) without photoirradiation at room temperature. NAD(+) exhibited an inhibitory behavior in both catalytic hydrogenation of NAD(+) with H(2) and H(2) evolution from NADH due to the binding of NAD(+) to the catalyst. The overall catalytic mechanism of interconversion between NADH and NAD(+) accompanied by generation and consumption of H(2) was revealed on the basis of the kinetic analysis and detection of the catalytic intermediates.

  18. Muscle activation and estimated relative joint force during running with weight support on a lower-body positive pressure treadmill

    DEFF Research Database (Denmark)

    Jensen, Bente Rona; Hovgaard-Hansen, Line; Cappelen, Katrine Louise

    2016-01-01

    Running on a lower-body positive pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg...... muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100, 80, 60, 40 and 20% body-weight (BW). Surface EMG, ground reaction force and running characteristics were measured. Relative knee and ankle joint forces were...... estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and anti-gravity forces. At 20%BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100%BW values. Plantar flexors decreased to 52% and 58% at 20%BW...

  19. Facile preparation of N-doped TiO2 at ambient temperature and pressure under UV light with 4-nitrophenol as the nitrogen source and its photocatalytic activities.

    Science.gov (United States)

    Horikoshi, Satoshi; Shirasaka, Yutaro; Uchida, Hiroshi; Horikoshi, Natsuko; Serpone, Nick

    2016-08-04

    To date syntheses of nitrogen-doped TiO2 photocatalysts (TiO2-xNx) have been carried out under high temperatures and high pressures with either NH3 or urea as the nitrogen sources. This article reports for the first time the facile preparation of N-doped TiO2 (P25 titania) in aqueous media at ambient temperature and pressure under inert conditions (Ar- and N2-purged dispersions) with 4-nitrophenol (or 4-nitrobenzaldehyde) as the nitrogen source. The resulting N-doped P25 TiO2 materials were characterized by UV/Vis and X-ray photoelectron spectroscopies (XPS) that confirmed the presence of nitrogen within the photocatalyst; X-ray diffraction (XRD) techniques confirmed the crystalline phases of the doped material. The photocatalytic activity of N-doped TiO2 was assessed through examining the photodegradation of 4-chlorophenol in aqueous media and iso-propanol as a volatile pollutant under UV/Vis and visible-light irradiation. Under visible light irradiation, undoped P25 was inactive contrary to N-doped P25 that successfully degraded 95% of the 4-chlorophenol (after 10 h) and 23% of iso-propanol (after 2.5 h).

  20. Collision-Induced Dissociation Study of the Adduct Ions Produced in NO3 (-)-Free Area of Atmospheric Pressure Negative Corona Discharges under Ambient Air Conditions.

    Science.gov (United States)

    Sekimoto, Kanako; Matsuda, Natsuki; Takayama, Mitsuo

    2013-01-01

    Collision-induced dissociation (CID) experiments of adducts [M+R](-) with negative atmospheric ions R(-) (O2 (-), HCO3 (-) and COO(-)(COOH)) produced in NO3 (-)-free discharge area in atmospheric pressure corona discharge ionization (APCDI) method were performed using aliphatic and aromatic compounds M. The [M+R](-) adducts for individual R(-) fragmented to form deprotonated analytes [M-H](-) as well as the specific product ions which also occurred in the CID of [M-H](-), independent of analytes with several different functional groups. The results obtained suggested that the specific product ions formed in the CID of [M+R](-), as well as CID of [M-H](-), are generated due to further fragmentation of the product ions [M-H](-). It was concluded, therefore, that CID of [M+R](-) formed in NO3 (-)-free discharge area can indirectly lead to the formation of the product ions originating from [M-H](-).

  1. Relationship between brain atrophy estimated by a longitudinal computed tomography study and blood pressure control in patients with essential hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Yamano, Shigeru; Sawai, Fuyuki; Yamamoto, Yuta [Nara Medical Univ., Kashihara (Japan)] [and others

    1999-01-01

    To evaluate the relationship between blood pressure control and the progression of brain atrophy in the elderly, patients with essential hypertension and brain atrophy were longitudinally evaluated using computerized tomography (CT). The study evaluated 48 patients with essential hypertension aged 46-78 years, and 30 sex- and age-matched normotensive control subjects. The extent of brain atrophy as determined by caudate head index (CHI), the inverse cella media index (iCMI), and Evans` ratio (ER) was estimated twice at an interval of 5-9 years (mean, 6.9 years). The mean annual increases in CHI ({Delta}CHI), iCMI ({Delta}iCMI), and ER ({Delta}ER) were evaluated. Mean blood volume in the common carotid artery (BF) and the decrease in BF per year ({Delta}BF) were also determined. The {Delta}CHI, {Delta}iCMI, and {Delta}ER increased with age in the hypertensive subjects as well as the control group across all age groups evaluated. The {Delta}CHI, {Delta}iCMI, and {Delta}ER were significantly greater in the patients with essential hypertension in their 50s as compared with the controls. In patients with essential hypertension aged 65 years or older, the {Delta}CHI, {Delta}iCMI, and {Delta}ER were significantly lower in the group in whom the blood pressure was controlled within the range of borderline hypertension than the groups in which it was controlled in the range of normal or mild hypertension. In the younger patients under the age of 65 with essential hypertension, blood pressure control did not affect the {Delta}CHI, {Delta}iCMI, and {Delta}ER. The {Delta}CHI, {Delta}iCMI, and {Delta}ER were significantly correlated with {Delta}BF in both groups. These findings indicate that control of systolic blood pressure within the range of borderline hypertension may delay the progression of brain atrophy in elderly patients with essential hypertension. (author)

  2. Estimation of the Young's modulus of the human pars tensa using in-situ pressurization and inverse finite-element analysis.

    Science.gov (United States)

    Rohani, S Alireza; Ghomashchi, Soroush; Agrawal, Sumit K; Ladak, Hanif M

    2017-03-01

    Finite-element models of the tympanic membrane are sensitive to the Young's modulus of the pars tensa. The aim of this work is to estimate the Young's modulus under a different experimental paradigm than currently used on the human tympanic membrane. These additional values could potentially be used by the auditory biomechanics community for building consensus. The Young's modulus of the human pars tensa was estimated through inverse finite-element modelling of an in-situ pressurization experiment. The experiments were performed on three specimens with a custom-built pressurization unit at a quasi-static pressure of 500 Pa. The shape of each tympanic membrane before and after pressurization was recorded using a Fourier transform profilometer. The samples were also imaged using micro-computed tomography to create sample-specific finite-element models. For each sample, the Young's modulus was then estimated by numerically optimizing its value in the finite-element model so simulated pressurized shapes matched experimental data. The estimated Young's modulus values were 2.2 MPa, 2.4 MPa and 2.0 MPa, and are similar to estimates obtained using in-situ single-point indentation testing. The estimates were obtained under the assumptions that the pars tensa is linearly elastic, uniform, isotropic with a thickness of 110 μm, and the estimates are limited to quasi-static loading. Estimates of pars tensa Young's modulus are sensitive to its thickness and inclusion of the manubrial fold. However, they do not appear to be sensitive to optimization initialization, height measurement error, pars flaccida Young's modulus, and tympanic membrane element type (shell versus solid).

  3. Methods for Estimating Uncertainty in PMF Solutions: Examples with Ambient Air and Water Quality Data and Guidance on Reporting PMF Results

    Science.gov (United States)

    The new version of EPA’s positive matrix factorization (EPA PMF) software, 5.0, includes three error estimation (EE) methods for analyzing factor analytic solutions: classical bootstrap (BS), displacement of factor elements (DISP), and bootstrap enhanced by displacement (BS-DISP)...

  4. Simultaneous detection of polar and nonpolar compounds by ambient mass spectrometry with a dual electrospray and atmospheric pressure chemical ionization source.

    Science.gov (United States)

    Cheng, Sy-Chyi; Jhang, Siou-Sian; Huang, Min-Zong; Shiea, Jentaie

    2015-02-03

    A dual ionization source combining electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) was developed to simultaneously ionize both polar and nonpolar compounds. The source was constructed by inserting a fused silica capillary into a stainless steel column enclosed in a glass tube. A high dc voltage was applied to a methanol solution flowing in the fused silica capillary to generate an ESI plume at the capillary tip. A high ac voltage was applied to a ring electrode attached to the glass tube to generate plasma from the nitrogen gas flowing between the glass tube and the stainless steel column. The concentric arrangement of the ESI plume and the APCI plasma in the source ensured that analytes entering the ionization region interacted with both ESI and APCI primary ion species generated in the source. Because the high voltages required for ESI and APCI were independently applied and controlled, the dual ion source could be operated in ESI-only, APCI-only, or ESI+APCI modes. Analytes were introduced into the ESI and/or APCI plumes by irradiating sample surfaces with a continuous-wavelength laser or a pulsed laser beam. Analyte ions could also be produced by directing the dual ESI+APCI source toward sample surfaces for desorption and ionization. The ionization mechanisms involved in the dual ion source include Penning ionization, ion molecule reactions, and fused-droplet electrospray ionization. Standards of polycyclic aromatic hydrocarbons, angiotensin I, lidocaine, ferrocene, diesel, and rosemary oils were used for testing. Protonated analyte ions were detected in ESI-only mode, radical cations were detected in APCI-only mode, and both types of ions were detected in ESI+APCI mode.

  5. 常温及常压至1.2GPa条件下异辛烷的拉曼光谱研究%Research on Raman Spectra of Isooctane at Ambient Temperature and Ambient Pressure to 1.2 GPa

    Institute of Scientific and Technical Information of China (English)

    张菲菲; 郑海飞

    2012-01-01

    利用碳化硅压腔在室温(25℃)下,研究了异辛烷(2,2,4-三甲基戊烷)在常压至1.2 GPa条件下的拉曼光谱特征.研究结果表明,异辛烷CH2和CHs的碳氢伸缩振动的拉曼位移随着压力的增大均呈线性向高频方向移动,其拉曼位移与压力的函数关系为:v2873=0.0028P+2873.3;v2905=0.0048P+2905.4;v2935=0.0027P+2935.0;v2960=0.012P+2960.9.在1.0 GPa附近,异辛烷的拉曼位移出现突变,与显微镜下观察发生的异辛烷液-固相变一致.结合异辛烷在常压下的熔点数据,获得了异辛烷的液-固两相相图,并根据克拉贝龙方程获得了液-固相转变过程中的摩尔体积变化量△Vm=4.46×10-6m3·mol-1和熵变△S=-30.32 J.K-1.mol-1.%The experimental study of the Raman spectral character for liquid isooctane(2,2,4-trimethylpentane, ATM) was conducted by moissanite anvil cell at the pressure of 0~l. 2 Gpa and the ambient temperature. The results show that the Raman peaks of the C-H stretching vibration shift to higher frenquencies with increasing pressures. The relations between the system pressure and peaks positions is given as following: v2873=0. 002 8P+2 873. 3; v2905 =0. 004 8P+2 905. 4; V2935 =0. 002 7P+ 2 935. 0; V2 960 =0. 012P+2 960. 9. The Raman spectra of isooctane abruptly changed at the pressure about 1.0 Gpa and the liquid-solid phase transition was observed by microscope. With the freezing pressure at ambient temperature and the melting temperature available at 1 atm, the authors got the liquid-solid phase diagram of isooctane. According to Clapeyron equation, the authors obtained the differences of volume and entropy for the liquid-solid phase transition of isooctane: △Vm =4. 46×10-6 m3 ? Mol-1 and △S=-30. 32 J ? K-1 ? Mol-1.

  6. Evaluation of force plate-less estimation of the trajectory of the centre of pressure during gait. Comparison of two anthropometric models.

    Science.gov (United States)

    Pillet, Hélène; Bonnet, Xavier; Lavaste, François; Skalli, Wafa

    2010-02-01

    The estimation of the trajectory of the centre of pressure during gait is possible without using force plate by modelling the whole body as a multi-segment chain. The kinematics and inertial parameters of each segment are necessary to determine the ground reaction forces and moments. The position of the centre of pressure can then be calculated at each frame of time. The objective of the study was to evaluate the accuracy of the estimation of the position of the centre of pressure during gait obtained without force plate data. Segment inertial parameters were determined using a proportional model and a geometric model. The modelling and calculations were computed for six volunteers and the estimated centres of pressure were compared to the centre of pressure measured using force plates considered as the gold standard. The estimation was better using the geometric model with an accuracy of 33 mm (4.1% of the peak-to-peak amplitude) on the longitudinal axis and 14.2 mm (12.9% of the peak-to-peak amplitude) on the lateral axis.

  7. Doppler Tissue Imaging: A Non-Invasive Technique for Estimation of Left Ventricular End Diastolic Pressure in Severe Mitral Regurgitation

    Directory of Open Access Journals (Sweden)

    Mojtaba Salarifar

    2010-08-01

    Full Text Available Background: Conventional Doppler measurements, including mitral inflow and pulmonary venous flow, are used to estimate left ventricular end diastolic pressure (LVEDP. However, these parameters have limitations in predicting LVEDP among patients with mitral regurgitation. This study sought to establish whether the correlation between measurements derived from tissue Doppler echocardiography and LVEDP remains valid in the setting of severe mitral regurgitation.Methods: Thirty patients (mean age: 57.37 ± 13.29 years with severe mitral regurgitation and a mean left ventricular ejection fraction (EF of 46.0 ± 14.95 were enrolled; 16 (53.4% patients were defined to have EF < 50% and 14 (46.6% patients had EF ≥ 50%. Doppler signals from the mitral inflow, pulmonary venous flow, and Doppler tissue imaging indices were obtained, and LVEDP was measured invasively through cardiac catheterization.Results: The majority of the standard Doppler and Doppler tissue imaging indices were not significantly correlated with LVEDP in the univariate analysis. In the multiple linear regression, however, early (E transmitral velocity to annular E' (E/E' ratio (ß = 1.09, p value < 0.01, E wave velocity to propagation velocity (E/Vp ratio (ß = 7.87, p value < 0.01, and isovolumic relaxation time (ß = 0.21, p value = 0.01 were shown as independent predictors of LVEDP (R2 = 91.7%.Conclusion: The ratio of E/Vp and E/E' ratio and also the isovolumic relaxation time could be applied properly to estimate LVEDP in mitral regurgitation patients even in the setting of severe mitral regurgitation.

  8. Short range shooting distance estimation using variable pressure SEM images of the surroundings of bullet holes in textiles.

    Science.gov (United States)

    Hinrichs, Ruth; Frank, Paulo Ricardo Ost; Vasconcellos, M A Z

    2017-03-01

    Modifications of cotton and polyester textiles due to shots fired at short range were analyzed with a variable pressure scanning electron microscope (VP-SEM). Different mechanisms of fiber rupture as a function of fiber type and shooting distance were detected, namely fusing, melting, scorching, and mechanical breakage. To estimate the firing distance, the approximately exponential decay of GSR coverage as a function of radial distance from the entrance hole was determined from image analysis, instead of relying on chemical analysis with EDX, which is problematic in the VP-SEM. A set of backscattered electron images, with sufficient magnification to discriminate micrometer wide GSR particles, was acquired at different radial distances from the entrance hole. The atomic number contrast between the GSR particles and the organic fibers allowed to find a robust procedure to segment the micrographs into binary images, in which the white pixel count was attributed to GSR coverage. The decrease of the white pixel count followed an exponential decay, and it was found that the reciprocal of the decay constant, obtained from the least-square fitting of the coverage data, showed a linear dependence on the shooting distance.

  9. Ambient particulate air pollution and acute lower respiratory infections: a systematic review and implications for estimating the global burden of disease.

    Science.gov (United States)

    Mehta, Sumi; Shin, Hwashin; Burnett, Rick; North, Tiffany; Cohen, Aaron J

    2013-03-01

    Acute lower respiratory infections (ALRI) account for nearly one fifth of mortality in young children worldwide and have been associated with exposures to indoor and outdoor sources of combustion-derived air pollution. A systematic review was conducted to identify relevant articles on air pollution and ALRI in children. Using a Bayesian approach to meta-analysis, a summary estimate of 1.12 (1.03, 1.30) increased risk in ALRI occurrence per 10 μg/m(3) increase in annual average PM2.5 concentration was derived from the longer-term (subchronic and chronic) effects studies. This analysis strengthens the evidence for a causal relationship between exposure to PM2.5 and the occurrence of ALRI and provides a basis for estimating the global attributable burden of mortality due to ALRI that is not influenced by the wide variation in regional case fatality rates. Most studies, however, have been conducted in settings with relatively low levels of PM2.5. Extrapolating their results to other, more polluted, regions will require a model that is informed by evidence from studies of the effects on ALRI of exposure to PM2.5 from other combustion sources, such as secondhand smoke and household solid fuel use.

  10. Estimation of the toxicity of sulfadiazine to Daphnia magna using negligible depletion hollow-fiber liquid-phase microextraction independent of ambient pH

    Science.gov (United States)

    Liu, Kailin; Xu, Shiji; Zhang, Minghuan; Kou, Yahong; Zhou, Xiaomao; Luo, Kun; Hu, Lifeng; Liu, Xiangying; Liu, Min; Bai, Lianyang

    2016-12-01

    The toxicity of ionizable organic compounds to organisms depends on the pH, which therefore affects risk assessments of these compounds. However, there is not a direct chemical method to predict the toxicity of ionizable organic compounds. To determine whether hollow-fiber liquid-phase microextraction (HF-LPME) is applicable for this purpose, a three-phase HF-LPME was used to measure sulfadiazine and estimate its toxicity to Daphnia magna in solutions of different pH. The result indicated that the sulfadiazine concentrations measured by HF-LPME decreased with increasing pH, which is consistent with the decreased toxicity. The concentration immobilize 50% of the daphnids (EC50) in 48 h calculated from nominal concentrations increased from 11.93 to 273.5 mg L-1 as the pH increased from 6.0 to 8.5, and the coefficient of variation (CV) of the EC50 values reached 104.6%. When calculated from the concentrations measured by HF-LPME (pH 12 acceptor phase), the EC50 ranged from 223.4 to 394.6 mg L-1, and the CV decreased to 27.60%, suggesting that the concentrations measured by HF-LPME can be used to estimate the toxicity of sulfadiazine irrespective of the solution pH.

  11. Ambient air quality measurements from a continuously moving mobile platform: Estimation of area-wide, fuel-based, mobile source emission factors using absolute principal component scores

    Science.gov (United States)

    Larson, Timothy; Gould, Timothy; Riley, Erin A.; Austin, Elena; Fintzi, Jonathan; Sheppard, Lianne; Yost, Michael; Simpson, Christopher

    2017-03-01

    We have applied the absolute principal component scores (APCS) receptor model to on-road, background-adjusted measurements of NOx, CO, CO2, black carbon (BC), and particle number (PN) obtained from a continuously moving platform deployed over nine afternoon sampling periods in Seattle, WA. Two Varimax-rotated principal component features described 75% of the overall variance of the observations. A heavy-duty vehicle feature was correlated with black carbon and particle number, whereas a light-duty feature was correlated with CO and CO2. NOx had moderate correlation with both features. The bootstrapped APCS model predictions were used to estimate area-wide, average fuel-based emission factors and their respective 95% confidence limits. The average emission factors for NOx, CO, BC and PN (14.8, 18.9, 0.40 g/kg, and 4.3 × 1015 particles/kg for heavy duty vehicles, and 3.2, 22.4, 0.016 g/kg, and 0.19 × 1015 particles/kg for light-duty vehicles, respectively) are consistent with previous estimates based on remote sensing, vehicle chase studies, and recent dynamometer tests. Information on the spatial distribution of the concentrations contributed by these two vehicle categories relative to background during the sampling period was also obtained.

  12. Estimation of the in-cylinder air/fuel ratio of an internal combustion engine by the use of pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Tunestaal, Per

    2000-03-01

    This thesis investigates the use of cylinder pressure measurements for estimation of the in-cylinder air/fuel ratio in a spark ignited internal combustion engine. An estimation model which uses the net heat release profile for estimating the cylinder air/fuel ratio of a spark ignition engine is developed. The net heat release profile is computed from the cylinder pressure trace and quantifies the conversion of chemical energy of the reactants in the charge into thermal energy. The net heat release profile does not take heat- or mass transfer into account. Cycle-averaged air/fuel ratio estimates over a range of engine speeds and loads show an RMS error of 4.1% compared to measurements in the exhaust. A thermochemical model of the combustion process in an internal combustion engine is developed. It uses a simple chemical combustion reaction, polynominal fits of internal energy as function of temperature, and the first law of thermodynamics to derive a relationship between measured cylinder pressure and the progress of the combustion process. Simplifying assumptions are made to arrive at an equation which relates the net heat release to the cylinder pressure. Two methods for estimating the sensor offset of a cylinder pressure transducer are developed. Both methods fit the pressure data during the pre-combustion phase of the compression stroke to a polytropic curve. The first method assumes a known polytropic exponent, and the other estimates the polytropic exponent. The first method results in a linear least-squares problem, and the second method results in a nonlinear least-squares problem. The nonlinear least-squares problem is solved by separating out the nonlinear dependence and solving the single-variable minimization problem. For this, a finite difference Newton method is derived. Using this method, the cost of solving the nonlinear least-squares problem is only slightly higher than solving the linear least-squares problem. Both methods show good statistical

  13. Size-resolved measurements of brown carbon and estimates of their contribution to ambient fine particle light absorption based on water and methanol extracts

    Science.gov (United States)

    Liu, J.; Bergin, M.; Guo, H.; King, L.; Kotra, N.; Edgerton, E.; Weber, R. J.

    2013-07-01

    Light absorbing organic carbon, often termed brown carbon, has the potential to significantly contribute to the visible light absorption budget, particularly at shorter wavelengths. Currently, the relative contributions of particulate brown carbon to light absorption, as well as the sources of brown carbon are poorly understood. With this in mind field measurements were made at both urban (Atlanta), and rural (Yorkville) sites in Georgia. Measurements in Atlanta were made at both a central site and a road side site adjacent to a main highway near the city center. Fine particle brown carbon optical absorption is estimated based on Mie calculations using direct size resolved measurements of chromophores in filter extracts. Size-resolved atmospheric aerosol samples were collected using a cascade impactor and analyzed for water-soluble organic carbon (WSOC), organic and elemental carbon (OC and EC), and solution light absorption spectra of water and methanol extracts. Methanol extracts were more light-absorbing than water extracts for all size ranges and wavelengths. Absorption refractive indices of the organic extracts were calculated from solution measurements for a range of wavelengths and used with Mie theory to predict the light absorption by fine particles comprised of these components, under the assumption that brown carbon and other aerosol components were externally mixed. For all three sites, chromophores were predominately in the accumulation mode with an aerodynamic mean diameter of 0.5 μm, an optically effective size range resulting in predicted particle light absorption being a factor of 2 higher than bulk solution absorption. Fine particle absorption was also measured with a Multi-Angle Absorption Photometer (MAAP) and seven-wavelength Aethalometer. Scattering-corrected aethalometer and MAAP absorption were in good agreement at 670 nm and Mie-estimated absorption based on size-resolved EC data were within 30% of these optical instruments. When applied

  14. Size-resolved measurements of brown carbon and estimates of their contribution to ambient fine particle light absorption based on water and methanol extracts

    Directory of Open Access Journals (Sweden)

    J. Liu

    2013-07-01

    Full Text Available Light absorbing organic carbon, often termed brown carbon, has the potential to significantly contribute to the visible light absorption budget, particularly at shorter wavelengths. Currently, the relative contributions of particulate brown carbon to light absorption, as well as the sources of brown carbon are poorly understood. With this in mind field measurements were made at both urban (Atlanta, and rural (Yorkville sites in Georgia. Measurements in Atlanta were made at both a central site and a road side site adjacent to a main highway near the city center. Fine particle brown carbon optical absorption is estimated based on Mie calculations using direct size resolved measurements of chromophores in filter extracts. Size-resolved atmospheric aerosol samples were collected using a cascade impactor and analyzed for water-soluble organic carbon (WSOC, organic and elemental carbon (OC and EC, and solution light absorption spectra of water and methanol extracts. Methanol extracts were more light-absorbing than water extracts for all size ranges and wavelengths. Absorption refractive indices of the organic extracts were calculated from solution measurements for a range of wavelengths and used with Mie theory to predict the light absorption by fine particles comprised of these components, under the assumption that brown carbon and other aerosol components were externally mixed. For all three sites, chromophores were predominately in the accumulation mode with an aerodynamic mean diameter of 0.5 μm, an optically effective size range resulting in predicted particle light absorption being a factor of 2 higher than bulk solution absorption. Fine particle absorption was also measured with a Multi-Angle Absorption Photometer (MAAP and seven-wavelength Aethalometer. Scattering-corrected aethalometer and MAAP absorption were in good agreement at 670 nm and Mie-estimated absorption based on size-resolved EC data were within 30% of these optical instruments

  15. Importance of combined left atrial size and estimated pulmonary pressure for clinical outcome in patients presenting with heart failure with preserved ejection fraction

    DEFF Research Database (Denmark)

    Donal, Erwan; Lund, Lars H; Oger, Emmanuel

    2017-01-01

    Aims: Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome with various phenotypes and outcomes. The prognostic relevance of echocardiography and the E/e' ratio has previously been reported. We sought to study in addition, the value of estimated pulmonary pressure and left...

  16. Determination and environmental estimation of NORMs in marine sediment environment of offshore platforms; Determinacao e avaliacao ambiental de NORMs em sedimento marinho entorno de plataformas offshore

    Energy Technology Data Exchange (ETDEWEB)

    Vegueria, Sergio F. Jerez, E-mail: sfjerez@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Departamento de Quimica Analitica; Godoy, Jose M., E-mail: rccampos@puc-rio.br, E-mail: jmgodoy@puc-rio.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    The natural radioactive materials (NORM known as) are found in the earth's crust, and during the process of production of oil and gas are concentrated in the produced water and the fouling (scale) pipes used for extraction. The production of oil and gas from produced water comes, comprising: forming water (water naturally present in the well ); injection water , usually sea water previously injected into the well to maintaining the pressure while the oil is removed; and water condensed in some cases of gas production. A high radioactivity of {sup 226}Ra (natural grade of {sup 238}U) and {sup 228}Ra (from the natural series of {sup 232}Th) is detected in produced water due to the high solubility of radio in formation water as uranium and thorium, which are insoluble in this medium, remain the rock matrix. The study was conducted in the area of offshore oil production in the state of Rio de January and included the determination of uranium, {sup 226}Ra, {sup 210}Pb and {sup 228}Ra in marine sediment near the points of discharge of produced water from oil platforms. After the pre-treatment and digestion of samples, the determination of the natural uranium was performed on a mass spectrometer with inductively coupled plasma (ICP -MS). The activities of {sup 226}Ra and {sup 228}Ra were determined by high resolution gamma spectrometry through {sup 214}Bi and {sup 228}Ac , respectively. And in the case of {sup 210}Pb, a correction was made for self-absorption employing an external source of this radionuclide. The results showed that there is no impact in sediments in the vicinity of the studied platforms.

  17. Size-resolved measurements of brown carbon in water and methanol extracts and estimates of their contribution to ambient fine-particle light absorption

    Science.gov (United States)

    Liu, J.; Bergin, M.; Guo, H.; King, L.; Kotra, N.; Edgerton, E.; Weber, R. J.

    2013-12-01

    Light absorbing organic carbon, often called brown carbon, has the potential to significantly contribute to the visible light-absorption budget, particularly at shorter wavelengths. Currently, the relative contributions of particulate brown carbon to light absorption, as well as the sources of brown carbon, are poorly understood. With this in mind size-resolved direct measurements of brown carbon were made at both urban (Atlanta), and rural (Yorkville) sites in Georgia. Measurements in Atlanta were made at both a representative urban site and a road-side site adjacent to a main highway. Fine particle absorption was measured with a multi-angle absorption photometer (MAAP) and seven-wavelength Aethalometer, and brown carbon absorption was estimated based on Mie calculations using direct size-resolved measurements of chromophores in solvents. Size-resolved samples were collected using a cascade impactor and analyzed for water-soluble organic carbon (WSOC), organic and elemental carbon (OC and EC), and solution light-absorption spectra of water and methanol extracts. Methanol extracts were more light-absorbing than water extracts for all size ranges and wavelengths. Absorption refractive indices of the organic extracts were calculated from solution measurements for a range of wavelengths and used with Mie theory to predict the light absorption by fine particles comprised of these components, under the assumption that brown carbon and other aerosol components were externally mixed. For all three sites, chromophores were predominately in the accumulation mode with an aerodynamic mean diameter of 0.5 μm, an optically effective size range resulting in predicted particle light absorption being a factor of 2 higher than bulk solution absorption. Mie-predicted brown carbon absorption at 350 nm contributed a significant fraction (20 to 40%) relative to total light absorption, with the highest contributions at the rural site where organic to elemental carbon ratios were

  18. Psicologia do Ambiente

    OpenAIRE

    Antunes, Dalila; Bernardo, Fátima; Palma-Oliveira, José-Manuel

    2011-01-01

    Na aplicação da Psicologia à área do AMBIENTE importa em primeiro lugar definir o que se entende, neste contexto, por ambiente. O conceito é entendido como toda a envolvente que rodeia o ser humano. Referimo-nos pois ao espaço físico e aos estímulos que nele existem (som, ar, paisagem…), dirigindo-se a Psicologia do Ambiente ao estudo e intervenção sobre a forma como o ambiente influencia o indivíduo ou grupos, e sobre o modo como o comportamento dos indivíduos e grupos influenciam o ambiente...

  19. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  20. A New Approach in Pressure Transient Analysis: Using Numerical Density Derivatives to Improve Diagnosis of Flow Regimes and Estimation of Reservoir Properties for Multiple Phase Flow

    Directory of Open Access Journals (Sweden)

    Victor Torkiowei Biu

    2015-01-01

    Full Text Available This paper presents the numerical density derivative approach (another phase of numerical welltesting in which each fluid’s densities around the wellbore are measured and used to generate pressure equivalent for each phase using simplified pressure-density correlation, as well as new statistical derivative methods to determine each fluid phase’s permeabilities, and the average effective permeability for the system with a new empirical model. Also density related radial flow equations for each fluid phase are derived and semilog specialised plot of density versus Horner time is used to estimate k relative to each phase. Results from 2 examples of oil and gas condensate reservoirs show that the derivatives of the fluid phase pressure-densities equivalent display the same wellbore and reservoir fingerprint as the conventional bottom-hole pressure BPR method. It also indicates that the average effective kave ranges between 43 and 57 mD for scenarios (a to (d in Example 1.0 and 404 mD for scenarios (a to (b in Example 2.0 using the new fluid phase empirical model for K estimation. This is within the k value used in the simulation model and likewise that estimated from the conventional BPR method. Results also discovered that in all six scenarios investigated, the heavier fluid such as water and the weighted average pressure-density equivalent of all fluid gives exact effective k as the conventional BPR method. This approach provides an estimate of the possible fluid phase permeabilities and the % of each phase contribution to flow at a given point. Hence, at several dp' stabilisation points, the relative k can be generated.

  1. The association between pressure pain sensitivity, and answers to questionnaires estimating psychological stress level in the workplace. A feasibility study

    DEFF Research Database (Denmark)

    Ballegaard, Søren; Petersen, Pernille; Gyntelberg, Finn

    2012-01-01

    To examine the association between pressure pain sensitivity (PPS) at the sternum as a measure of persistent stress assessed by questionnaires in a working population.......To examine the association between pressure pain sensitivity (PPS) at the sternum as a measure of persistent stress assessed by questionnaires in a working population....

  2. Estimation of leaf area for greenhouse cucumber by linear measurements under salinity and grafting Estimativa da área foliar do pepino em ambiente protegido por medidas lineares sob salinidade e enxertia

    Directory of Open Access Journals (Sweden)

    Flávio Favaro Blanco

    2005-08-01

    Full Text Available The measurement of leaf area by linear parameters is a useful tool when plants cannot be destroyed for direct measurement. The objectives of this study were to establish equations to estimate the leaf area of greenhouse-cucumber and to evaluate the effects of salinity and grafting on this estimative. Non-grafted cucumber seedlings, cv. 'Hokushin', were transplanted in a greenhouse and were irrigated with water of different salinities (1.0, 3.2 and 5.0 dS m-1. In the second growing period, the same cultivar was grafted on Cucurbita spp. and the plants were irrigated with water of 1.4, 3.0 and 5.3 dS m-1. Leaves of different sizes were collected from both experiments and leaf area was determined by an integrating area meter. Leaf length (L and width (W were also recorded. An equation for estimating the leaf area from L and W was developed for a given salinity level or grafting condition and estimated well the area of leaves collected in the other treatments. The leaf area (LA of cucumber 'Hokushin' could be estimated using the equation LA = 0.88LW - 4.27, for any grafting and salinity conditions.A determinação da área foliar por medidas lineares é uma ferramenta útil quando as plantas não podem ser destruídas para que a medição direta seja realizada. Os objetivos desse trabalho foram definir equações para a estimativa da área foliar do pepino em ambiente protegido e avaliar os efeitos da salinidade e da a enxertia nessa estimativa. Mudas de pepino, cv. 'Hokushin', não enxertadas, foram transplantadas em um ambiente protegido e irrigadas com água de diferentes salinidades (1,0, 3,2 e 5,0 dS m-1. No segundo período de cultivo, a mesma cultivar foi enxertada sobre Cucurbita spp., sendo as plantas irrigadas com água de 1,4, 3,0 e 5,3 dS m-1. Foram coletadas folhas de diferentes tamanhos dos dois cultivos e dos três tratamentos e a área foliar foi determinada por um medidor de área foliar. O comprimento (C e a largura (L da folha

  3. Measure and estimation of the evapotranspiration of tomato plants cultivated with organic fertilization in protected ambient / Medida e estimativa da evapotranspiração do tomateiro cultivado sob adubação orgânica em ambiente protegido

    Directory of Open Access Journals (Sweden)

    Viviane Aires de Paula

    2010-09-01

    Full Text Available The present work had the aim of determining the water consumption for tomato crop cultivated in protected ambient under organic fertilization and of evaluating the estimates of evapotranspiration and of crop coefficients (Kc in greenhouse, with the use of the methods Class A Pan, Solar Radiation, Penman and Penman-Monteith. The experiment was carried out from September/2004 to January/2005, at the Campus of Universidade Federal de Pelotas, Brazil. The organic fertilization of the soil consisted of two doses of vermicompost from bovine manure, and ‘Floradade’ tomato plants were transplanted in 4/11/2004, with 0.50 x 0.70 m spacing. In the central part of the greenhouse, a datalogger was installed in order to receive the signals originated from the agrometeorologicals sensors installed in the greenhouse. In order to determine the water consumption of the plants, the method of water balance of the soil was used associated to evapotranspirometers, constructed in the central of the polyethylene greenhouse. The water consumption of the tomato plants in the 88 days of cultivation was of 477 mm. The estimation of the evapotranspiration for the methods Class A Pan, Solar Radiation and Penman, presented high precision and had agreement with the measured values of the crop evapotranspiration. The reference evapotranspiration presented values close to the crop evapotranspiration during the crop growth with the use of the methods Class A Pan, Solar Radiation and Penman, with Kc values of 0.95; 1.02; and 1.01, respectively, while for the Penman-Monteith method the Kc was 1.41.O presente trabalho teve por objetivos determinar o consumo hídrico do tomateiro com adubação orgânica e avaliar as estimativas da evapotranspiração e do coeficiente de cultura (Kc em ambiente protegido, com o uso dos métodos do Tanque Classe A, Radiação Solar, Penman e Penman-Monteith. O experimento foi conduzido de setembro de 2004 a janeiro de 2005, no Campus da

  4. Ferromagnetic behavior of the Ru{sub 1-x}Sr{sub 2}GdCu{sub 2+x}O{sub 8{+-}}{sub z} system with 0.0 < x < 1.0, synthesized at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Abatal, M. [IIM-UNAM, AP 70-360, 04510 Mexico D. F. (Mexico); Chavira, E. [IIM-UNAM, AP 70-360, 04510 Mexico D. F. (Mexico)], E-mail: chavira@servidor.unam.mx; Filippini, C. [LEPES-CNRS, 25 Ave. des Martyrs, BP 166, 38048 Grenoble (France); Garcia-Vazquez, V. [IF-LRT, BUAP, AP J-48, 72570 Puebla, Pue (Mexico); Perez, J.C.; Tholence, J.L. [LEPES-CNRS, 25 Ave. des Martyrs, BP 166, 38048 Grenoble (France)

    2008-10-01

    The Ru{sub 1-x}Sr{sub 2}GdCu{sub 2+x}O{sub 8{+-}}{sub z} system with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.9 and 1.0 was studied by differential thermal analysis (DTA) in air in order to determine the temperature interval at which the formation of the RuSr{sub 2}GdCu{sub 2}O{sub 8} (Ru-1212) compound should be formed. For DTA data, samples were prepared by the solid-state reaction method at ambient pressure between 940 deg. C and 1050 deg. C. From the X-ray powder diffraction (XRD) patterns it was observed that this system is isostructural to the Ru-1212 compound. In addition, a pure phase up to x = 0.4 was obtained. Studies by the Scanning Electron Microscopy (SEM) technique produced a particle size around 1-5 {mu}m. The results of Transmission Electronic Microscopy (TEM) studies confirm the tetragonal unit cell in the Ru{sub 1-x}Sr{sub 2}GdCu{sub 2+x}O{sub 8{+-}}{sub z} system. The temperature dependence of the electrical resistivity of the samples with x = 0.1, 0.2 and 0.4 annealed in oxygen flux for 6, 12 and 41 h, at T = 960 deg. C, shows a semiconducting behavior. The AC magnetic susceptibility measurement indicates ferromagnetic behavior with T{sup Curie} between 130 and 138 K.

  5. A Semi-Analytical Method for Rapid Estimation of Near-Well Saturation, Temperature, Pressure and Stress in Non-Isothermal CO2 Injection

    Science.gov (United States)

    LaForce, T.; Ennis-King, J.; Paterson, L.

    2015-12-01

    Reservoir cooling near the wellbore is expected when fluids are injected into a reservoir or aquifer in CO2 storage, enhanced oil or gas recovery, enhanced geothermal systems, and water injection for disposal. Ignoring thermal effects near the well can lead to under-prediction of changes in reservoir pressure and stress due to competition between increased pressure and contraction of the rock in the cooled near-well region. In this work a previously developed semi-analytical model for immiscible, nonisothermal fluid injection is generalised to include partitioning of components between two phases. Advection-dominated radial flow is assumed so that the coupled two-phase flow and thermal conservation laws can be solved analytically. The temperature and saturation profiles are used to find the increase in reservoir pressure, tangential, and radial stress near the wellbore in a semi-analytical, forward-coupled model. Saturation, temperature, pressure, and stress profiles are found for parameters representative of several CO2 storage demonstration projects around the world. General results on maximum injection rates vs depth for common reservoir parameters are also presented. Prior to drilling an injection well there is often little information about the properties that will determine the injection rate that can be achieved without exceeding fracture pressure, yet injection rate and pressure are key parameters in well design and placement decisions. Analytical solutions to simplified models such as these can quickly provide order of magnitude estimates for flow and stress near the well based on a range of likely parameters.

  6. Estimated aortic blood pressure based on radial artery tonometry underestimates directly measured aortic blood pressure in patients with advancing chronic kidney disease staging and increasing arterial stiffness

    DEFF Research Database (Denmark)

    Carlsen, Rasmus K; Peters, Christian D; Khatir, Dinah S;

    2016-01-01

    we compared invasive aortic systolic BP (SBP) with estimated central SBP obtained by radial artery tonometry and examined the influence of renal function and arterial stiffness on this relationship. We evaluated 83 patients with stage 3 to 5 CKD (mean estimated glomerular filtration rate [eGFR] 30 ml......% confidence interval -14.9 to -11.4) mm Hg. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cf-PWV) and was significantly increased in CKD patients compared with (versus) control patients (mean 10.7 vs. 9.3 m/s). The difference in BP significantly increased 1.0 mm Hg for every 10 ml....../min decrease in eGFR and by 1.6 mm Hg per 1 m/s increase in cfPWV. Using multivariate regression analysis including both eGFR and cfPWV, the difference between estimated central and invasive aortic SBP was significantly increased by 0.7 mm Hg. For the entire cohort brachial SBP significantly better reflected...

  7. Self-reported alcohol intake is a better estimate of 5-year change in blood pressure than biochemical markers in low resource settings: the PURE study

    OpenAIRE

    Zatu, Mandlenkosi C.; Van Rooyen, Johannes M.; Du Toit, Loots; Wentzel-Viljoen, Edelweiss; Greeff, Minrie; Schutte, Aletta E.

    2014-01-01

    Background: Despite criticism of self-reported alcohol intake, it is a valuable tool to screen for alcohol abuse as a risk factor for cardiovascular disease. We aimed to compare various self-reported estimates of alcohol use with γ-glutamyltransferase (GGT) and percentage carbohydrate deficient transferrin (%CDT) considering their relationship with blood pressure changes (%BP) over a 5-year period in black South Africans. Method: We recruited 1994 participants and collected 5-year followe...

  8. Photometric measurement of color changes in livor mortis as a function of pressure and time. Development of a computer-aided system for measuring pressure-induced blanching of livor mortis to estimate time of death.

    Science.gov (United States)

    Kaatsch, H J; Stadler, M; Nietert, M

    1993-01-01

    Until now, blanching of livor mortis in estimating time of death has generally been assessed based on subjective impressions, i.e. on whether blanching is visible after the application of pressure. We have developed a measuring system that uses digital processing to objectify the relationship between the pressure applied and blanching of postmortem lividity. The pressure is electronically registered by a strain gauge. At predefined levels (10, 20, 30, up to 100 N) the software triggers a color measurement by a commercially available tristimulus colorimeter. All parameters are measured in a single procedure and routed to the computer through a data interface. The pressure-induced color changes in the livor mortis are evaluated according to the L*, a*, b* system (CIE-LAB according to DIN 5033, DIN 6174), which closely approximates the physiology of sight. An additional color spacing formula (delta E) allows analysis of color changes irrespective of the basic skin tone. Initial measurements on cadavers showed that application of increasing pressure produced regular courses of color changes in livor mortis.

  9. DERECHO AMBIENTAL EN ARGENTINA

    OpenAIRE

    2014-01-01

    El objetivo de la presente publicación es brindar un panorama general, introductorio y actualizado del derecho ambiental argentino. Entendiendo que el derecho ambiental es un signo de nuestra era y que por la dinamicidad de la cuestión ambiental requiere de permanente actualización regularoria. La autora desarrolla en forma objetiva su postura en relación con la necesidad de hacer sostenible al derecho ambiental. Para luego analizar brevemente la situación actual del derecho vigente en Argent...

  10. Preliminary investigation of an ultrasound method for estimating pressure changes in deep-positioned vessels

    DEFF Research Database (Denmark)

    Olesen, Jacob Bjerring; Villagómez Hoyos, Carlos Armando; Traberg, Marie Sand;

    2016-01-01

    This paper presents a method for measuring pressure changes in deep-tissue vessels using vector velocity ultrasound data. The large penetration depth is ensured by acquiring data using a low frequency phased array transducer. Vascular pressure changes are then calculated from 2-D angle-independen......This paper presents a method for measuring pressure changes in deep-tissue vessels using vector velocity ultrasound data. The large penetration depth is ensured by acquiring data using a low frequency phased array transducer. Vascular pressure changes are then calculated from 2-D angle......-independent vector velocity fields using a model based on the Navier-Stokes equations. Experimental scans are performed on a fabricated flow phantom having a constriction of 36% at a depth of 100 mm. Scans are carried out using a phased array transducer connected to the experimental scanner, SARUS. 2-D fields...... of angle-independent vector velocities are acquired using directional synthetic aperture vector flow imaging. The obtained results are evaluated by comparison to a 3-D numerical simulation model with equivalent geometry as the designed phantom. The study showed pressure drops across the constricted phantom...

  11. Estimating maximum instantaneous distortion from inlet total pressure rms and PSD measurements. [Root Mean Square and Power Spectral Density methods

    Science.gov (United States)

    Melick, H. C., Jr.; Ybarra, A. H.; Bencze, D. P.

    1975-01-01

    An inexpensive method is developed to determine the extreme values of instantaneous inlet distortion. This method also provides insight into the basic mechanics of unsteady inlet flow and the associated engine reaction. The analysis is based on fundamental fluid dynamics and statistical methods to provide an understanding of the turbulent inlet flow and quantitatively relate the rms level and power spectral density (PSD) function of the measured time variant total pressure fluctuations to the strength and size of the low pressure regions. The most probable extreme value of the instantaneous distortion is then synthesized from this information in conjunction with the steady state distortion. Results of the analysis show the extreme values to be dependent upon the steady state distortion, the measured turbulence rms level and PSD function, the time on point, and the engine response characteristics. Analytical projections of instantaneous distortion are presented and compared with data obtained by a conventional, highly time correlated, 40 probe instantaneous pressure measurement system.

  12. Estimated aortic blood pressure based on radial artery tonometry underestimates directly measured aortic blood pressure in patients with advancing chronic kidney disease staging and increasing arterial stiffness.

    Science.gov (United States)

    Carlsen, Rasmus K; Peters, Christian D; Khatir, Dinah S; Laugesen, Esben; Bøtker, Hans Erik; Winther, Simon; Buus, Niels H

    2016-10-01

    Central blood pressure (BP) can be assessed noninvasively based on radial tonometry and may potentially be a better predictor of clinical outcome than brachial BP. However, the validity of noninvasively obtained estimates has never been examined in patients with chronic kidney disease (CKD). Here we compared invasive aortic systolic BP (SBP) with estimated central SBP obtained by radial artery tonometry and examined the influence of renal function and arterial stiffness on this relationship. We evaluated 83 patients with stage 3 to 5 CKD (mean estimated glomerular filtration rate [eGFR] 30 ml/min/1.73 m(2)) and 41 controls without renal disease undergoing scheduled coronary angiography. BP in the ascending aorta was measured through the angiography catheter and simultaneously estimated using radial tonometry. The mean difference between estimated central and aortic SBP was -13.2 (95% confidence interval -14.9 to -11.4) mm Hg. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cf-PWV) and was significantly increased in CKD patients compared with (versus) control patients (mean 10.7 vs. 9.3 m/s). The difference in BP significantly increased 1.0 mm Hg for every 10 ml/min decrease in eGFR and by 1.6 mm Hg per 1 m/s increase in cfPWV. Using multivariate regression analysis including both eGFR and cfPWV, the difference between estimated central and invasive aortic SBP was significantly increased by 0.7 mm Hg. For the entire cohort brachial SBP significantly better reflected invasive SBP than estimated SBP. Thus, tonometry-based estimates of central BP progressively underestimate invasive central SBP with decreasing renal function and increasing arterial stiffness in CKD patients.

  13. Radiactividad y medio ambiente

    OpenAIRE

    Sánchez León, José Guillermo

    1993-01-01

    En los medios de comunicación frecuentemente aparecen noticias que hacen referencia a la radiactividad y al medio ambiente y, sin embargo, lo que es la radiactividad y como influye ésta sobre el medio ambiente suele ser poco conocido, incluso por personas de formación científica.

  14. The Novel Method to Estimate Effect of Cement Slurry Consistency toward Friction Pressure in Oil/Gas Well Cementing

    Directory of Open Access Journals (Sweden)

    Adrian Pattinasarany

    2012-11-01

    Full Text Available The aim of this study is to investigate effect of cement slurry consistency toward friction pressure during oil/gas cementing operation. Completion of an oil/gas well has become more important because the reserve has become harder to find. The oil/gas company cannot afford to lose million dollars they spent when locating, drilling and recovering the oil from the Earth if they failed it. The safety, health and environment also have become more important issue, because any completion problem can lead to prolong operation and creating more hazard and risk. Cementing operation plays a very important role during completion because it creates a secure conduit to bring the precious oil/gas to the surface and a place to install completion jewelry. During cementing operation lost circulation can be one of the serious problems that arise. Circulation is said to be lost when the cement slurry pumped flows into one or more geological formations instead of returning up casing annulus. This is due to sum of hydrostatic pressure and friction pressure is exceeding fracture gradient. Method that commonly used to calculate friction from American Petroleum Institute (API assumed the cement slurry will exhibit time independent nature. Cement slurry consistency was found to have significant effect to friction pressure.

  15. Selection of a Suitable Wall Pressure Spectrum Model for Estimating Flow-Induced Noise in Sonar Applications

    Directory of Open Access Journals (Sweden)

    V. Bhujanga Rao

    1995-01-01

    Full Text Available Flow-induced structural noise of a sonar dome in which the sonar transducer is housed, constitutes a major source of self-noise above a certain speed of the vessel. Excitation of the sonar dome structure by random pressure fluctuations in turbulent boundary layer flow leads to acoustic radiation into the interior of the dome. This acoustic radiation is termed flow-induced structural noise. Such noise contributes significantly to sonar self-noise of submerged vessels cruising at high speed and plays an important role in surface ships, torpedos, and towed sonars as well. Various turbulent boundary layer wall pressure models published were analyzed and the most suitable analytical model for the sonar dome application selected while taking into account high frequency, fluid loading, low wave number contribution, and pressure gradient effects. These investigations included type of coupling that exists between turbulent boundary layer pressure fluctuations and dome wall structure of a typical sonar dome. Comparison of theoretical data with measured data onboard a ship are also reported.

  16. DERECHO AMBIENTAL EN ARGENTINA

    Directory of Open Access Journals (Sweden)

    Silvia Nonna

    2014-05-01

    Full Text Available El objetivo de la presente publicación es brindar un panorama general, introductorio y actualizado del derecho ambiental argentino. Entendiendo que el derecho ambiental es un signo de nuestra era y que por la dinamicidad de la cuestión ambiental requiere de permanente actualización regulatoria. La autora desarrolla en forma objetiva su postura en relación con la necesidad de hacer sostenible al derecho ambiental. Para luego analizar brevemente la situación actual del derecho vigente en Argentina, haciendo un rápido y resumido recorrido desde la última reforma de la Constitución Nacional hasta la consideración especial de cada una de las nuevas normas de presupuestos mínimos de protección ambiental.

  17. Liquid Water Structure from Anomalous Density under Ambient Condition

    Institute of Scientific and Technical Information of China (English)

    SUN Qiang; ZHENG Hai-Fei

    2006-01-01

    @@ From discussion of the structure of liquid water, we deduce that water under ambient condition is mainly composed of ice Ih-like molecular clusters and clathrate-like molecular clusters. The water molecular clusters remain in a state of chemical equilibrium (reversible clustering reactions). This structural model can be demonstrated by quantitative study on anomalous density with increasing temperature at ambient pressure.

  18. Non-invasive estimation of pulsatile flow and differential pressure in an implantable rotary blood pump for heart failure patients.

    Science.gov (United States)

    AlOmari, A H; Savkin, A V; Karantonis, D M; Lim, E; Lovell, N H

    2009-04-01

    We propose dynamical models for pulsatile flow and head estimation in an implantable rotary blood pump. Pulsatile flow and head data were obtained using a circulatory mock loop where fluid solutions with different values of viscosities were used as a blood analogue with varying haematocrit (HCT). Noninvasive measurements of power and pump speed were used with HCT values as inputs to the flow model while the estimated flow was used with the speed as inputs to a head estimation model. Linear regression analysis between estimated and measured flows obtained from a mock loop resulted in a highly significant correlation (R2=0.982) and a mean absolute error (e) of 0.323 L min(-1), while for head, R2=0.933 and e=7.682 mmHg were obtained. R2=0.849 and e=0.584 L min(-1) were obtained when the same model derived in the mock loop was used for flow estimation in ex vivo porcine data (N=6). Furthermore, in the steady state, the solution of the presented flow model can be described by a previously designed and verified static model. The models developed herein will play a vital role in developing a robust control system of the pump flow coping with changing physiological demands.

  19. Equipment Errors: A Prevalent Cause for Fallacy in Blood Pressure Recording - A Point Prevalence Estimate from an Indian Health University

    OpenAIRE

    Badrinarayan Mishra; Nidhi Dinesh Sinha; Hitesh Gidwani; Sushil Kumar Shukla; Abhishek Kawatra; S. C. Mehta

    2013-01-01

    Background: Blood pressure (BP) recording is the most commonly measured clinical parameter. Standing mercury sphygmomanometer is the most widely used equipment to record this. However, recording by sphygmomanometer is subject to observer and instrumental error. The different sources of equipment error are faulty manometer tube calibration, baseline deviations and improper arm bladder cuff dimensions. This is further compounded by a high prevalence of arm bladder miss-cuffing in the target pop...

  20. Wideband high-resolution direction of arrival estimation method based on the pressure-velocity combined processing using the acoustic vector sensor array

    Institute of Scientific and Technical Information of China (English)

    BAI Xingyu; YANG Desen; ZHAO Chunhui

    2007-01-01

    In order to solve the problem of DOA (Direction of Arrival) estimation of underwater distant wideband targets, a novel coherent signal-subspace method based on the cross spectral matrix of pressure and particle velocity using the Acoustic Vector Sensor Array (AVSA)is proposed in this paper. The proposed method is different from existing AVSA based DOA estimation methods in using particle velocity information of Acoustic Vector Sensor (AVS) as an independent array element. It is entirely based on the combined information processing of pressure and particle velocity, namely, the P-V cross spectrum, has better DOA estimation performance than existing methods in isotropic noise field. By theoretical analysis, both focusing principle and eigendecomposition theory based on the P-V cross spectral matrix are given.At the same time, the corresponding criteria for source number detection is also presented.Computer simulations with data from lake trials demonstrate that the proposed method is effective and obviously outperforms existing methods in resolution and accuracy in the case of low Signal-to-Noise Ratio (SNR).

  1. Reconstruction of Full-Field Wall Pressure Fluctuations on a Flat Plate in the Wake of a Step Cylinder: Applications of Linear Stochastic Estimation (LSE)

    Science.gov (United States)

    Peng, Di; Chen, Yujia; Wang, Shaofei; Liu, Yingzheng; Wang, Weizhe

    2016-11-01

    Previous studies have shown that it is possible to reconstruct the full flow field based on time-resolved measurements at discrete locations using linear stochastic estimation (LSE). The objective of this study is to develop and apply this technique to wall pressure fluctuation measurements in low speed flows. Time-resolved wall pressure fluctuations on a flat plate in the wake of a step cylinder at low speed (V PSP). The microphone arrays are arranged properly to capture the dominant features in the flow field at 10 kHz. The PSP is excited using a continuous UV-LED, and the luminescent signal is recorded by a high-speed camera at 2 kHz. The microphone data at discrete locations are used to reconstruct the full-field wall pressure fluctuations based on LSE. The PSP results serve as basis for improvement of the LSE scheme and also for validation of the reconstructed pressure field. Other data processing techniques including proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are also used for analyzing the unsteady flow features. This LSE technique has great potential in real-time flow diagnostics and control.

  2. Ambient ionization mass spectrometry: A tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

    2011-09-19

    Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

  3. Crack Orientation and Depth Estimation in a Low-Pressure Turbine Disc Using a Phased Array Ultrasonic Transducer and an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Wenshuang Chang

    2013-09-01

    Full Text Available Stress corrosion cracks (SCC in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN, is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks.

  4. Crack orientation and depth estimation in a low-pressure turbine disc using a phased array ultrasonic transducer and an artificial neural network.

    Science.gov (United States)

    Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

    2013-09-13

    Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks.

  5. Muscle Activation and Estimated Relative Joint Force During Running with Weight Support on a Lower-Body Positive-Pressure Treadmill.

    Science.gov (United States)

    Jensen, Bente R; Hovgaard-Hansen, Line; Cappelen, Katrine L

    2016-08-01

    Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle). It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force.

  6. Major improvement of altimetry sea level estimations using pressure-derived corrections based on ERA-Interim atmospheric reanalysis

    Science.gov (United States)

    Carrere, Loren; Faugère, Yannice; Ablain, Michaël

    2016-06-01

    The new dynamic atmospheric correction (DAC) and dry tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed for the 1992-2013 altimeter period. Using these new corrections significantly improves sea level estimations for short temporal signals (SSH) error by more than 3 cm in the Southern Ocean and in some shallow water regions. The impact of DT_ERA (DT derived from ERA-Interim meteorological reanalysis) is also significant in the southern high latitudes for these missions. Concerning more recent missions (Jason-1, Jason-2, and Envisat), results are very similar between ERA-Interim and ECMWF-based corrections: on average for the global ocean, the operational DAC becomes slightly better than DAC_ERA only from the year 2006, likely due to the switch of the operational forcing to a higher spatial resolution. At regional scale, both DACs are similar in the deep ocean but DAC_ERA raises the residual crossovers' variance in some shallow water regions, indicating a slight degradation in the most recent years of the study. In the second decade of altimetry, unexpectedly DT_ERA still gives better results compared to the operational DT. Concerning climate signals, both DAC_ERA and DT_ERA have a low impact on global mean sea level rise (MSL) trends, but they can have a strong impact on long-term regional trends' estimation, up to several millimeters per year locally.

  7. Architectural models of ambient-PRISMA in channel ambient calculus

    OpenAIRE

    Ali, Nour; Tuosto, Emilio

    2011-01-01

    peer-reviewed Ambient-PRISMA is an architectural approach for specifying aspect-oriented software architecture and generating code of distributed and mobile systems. Ambient-PRISMA lacks a precise semantics due to the fact that it is based only on a metamodel. In this paper, Ambient-PRISMA is mapped into a formal language called Channel Ambient Calculus, a process algebra for specifying mobile applications that provides channels and ambients as first-class citizens. We...

  8. Ambient Response Analysis of the Great Belt Bridge

    DEFF Research Database (Denmark)

    Brincker, Rune; Frandsen, J. B.; Andersen, P.

    2000-01-01

    In this paper an ambient response analysis of the Great Belt Bridge is presented. The Great Belt Bridge is one of the largest suspension bridges in the world, and the analysis was carried out in order to investigate the possibilities of estimating reliable damping values from the ambient response...

  9. Estimation of C*-Integral for Radial Cracks in Annular Discs under Constant Angular Velocity and Internal Pressure

    Directory of Open Access Journals (Sweden)

    A. R. Gowhari-Anaraki

    2008-01-01

    Full Text Available The finite element method has been used to predict the creep rupture parameter, C*-Integral for single and double-edge cracks in eight annular rotating discs under constant angular velocity with and without internal pressure. In this study, a new dimensionless creeping crack configuration factor, Q* has been introduced. Power law creeping finite element analyses have been performed and the results are presented in the form of Q* for a wide range of components and crack geometry parameters. These parameters are chosen to be representative of typical practical situations and have been determined from evidence presented in the open literature. The extensive range of Q* obtained from the analyses are then used to obtain equivalent prediction equations using a statistical multiple non-linear regression model. The predictive equations for Q*, can also be used easily to calculate the C*-Integral values for extensive range of geometric parameters. The C*-Integral values obtained from predictive equations were also compared with those obtained from reference stress method (RSM. Finally, creep zone growth behavior was studied in the component during transient time.

  10. Ambient oxygen promotes tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Ho Joong Sung

    Full Text Available Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ∼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo.

  11. ESTIMATION OF PRECIPITABLE WATER VAPOR BASED ON INTERPOLATED PRESSURE DATA%基于插值气压的GPS反演大气可降水量研究

    Institute of Scientific and Technical Information of China (English)

    刘立龙; 姚朝龙; 熊思; 黄良珂

    2013-01-01

    The meteorological data are obtained by pressure interpolation for the estimation of GPS precipitable water vapor (PWV) due to the lack of meteorological parameters at GPS sites.The pressure interpolation formula based on segmented height difference is derived by analyzing the relationship between the interpolated pressure at the GPS sites and the pressure at the nearby radiosonde (RS) stations,and the relationship between the interpolated pressure of the GPS sites and the height difference between the IGS stations and the nearby radiosonde stations using the standard atmosphere (SA) model.The new pressure interpolation formula has the same accuracy as the SA model,and the former is simple when the height difference is less than 100 m.GPS PWV is derived from the new pressure interpolation formula,Saastamoinen zenith hydrostatic delay (ZHD) model and the local weighted mean temperature of the atmosphere (Tm).By comparing with RS PWV,the results show that the new pressure interpolation model can be used to calculate GPS PWV with no meteorological data at GPS stations which the RMS error between GPS PWV obtained from the pressure interpolation formula based on segmented height difference and RS PWV is 1-3 mm.%为解决GPS反演大气可降水量(PWV)所需的气象参数,通过标准大气(SA)模型分析插值得到了GPS站气压与相邻探空站气压、GPS站与探空站之间高差的关系,及基于分段高差的气压插值公式.该公式与标准大气模型精度相当,且在高差小于100 m时,其计算更为简单.利用新的气压插值公式、Saastamoinen干延迟模型与建立的局地加权平均温度模型,将四个IGS站(BJFS、KUNM、LHAZ和TWTF)提供的对流层天顶延迟转化得到大气可降水量(GPS PWV),与探空大气可降水量(RS PWV)进行对比,结果表明在不同高差条件下基于分段高差的气压插值模型计算得到的GPS PWV与RS PWV差值的均方根误差为1~3mm,说明该气压插值模型可应用于无气象数据的GPS反演PWV.

  12. Crisis ambiental y cristianismo

    OpenAIRE

    Felipe Cárdenas

    2008-01-01

    En el artículo se identifican y reconocen algunas opciones que se pueden desarrollar en el cristianismo en relación con la problemática ambiental. Se aborda el dilema bíblico suscitado por interpretaciones antiecológicas y ecológicas. Con base en una lectura de la Biblia, de testimonios cristianos, y en una rememoria de estructuras institucionales, como la parroquia, se analiza el valor que tiene el mensaje cristiano en lo referido a la mitigación de la crisis ambiental.This article identifie...

  13. Response of cyanobacteria to low atmospheric pressure

    Science.gov (United States)

    Qin, Lifeng; Yu, Qingni; Ai, Weidang; Tang, Yongkang; Ren, Jin; Guo, Shuangsheng

    2014-10-01

    Maintaining a low pressure environment in a controlled ecological life support system would reduce the technological complexity and resupply cost in the course of the construction of a future manned lunar base. To estimate the effect of a hypobaric environment in a lunar base on biological components, such as higher plants, microbes, and algae, cyanobacteria was used as the model by determining their response of growth, morphology, and physiology when exposed to half of standard atmospheric pressure for 16 days (brought back to standard atmospheric pressure 30 minutes every two days for sampling). The results indicated that the decrease of atmospheric pressure from 100 kPa to 50 kPa reduced the growth rates of Microcystis aeruginosa, Merismopedia sp., Anabaena sp. PCC 7120, and Anabaena flos-aquae. The ratio of carotenoid to chlorophyll a content in the four tested strains increased under low pressure conditions compared to ambient conditions, resulting from the decrease of chlorophyll a and the increase of carotenoid in the cells. Moreover, low pressure induced the reduction of the phycocyanin content in Microcystis aeruginosa, Anabaena sp. PCC 7120, and Anabaena flos-aquae. The result from the ultrastructure observed using SEM indicated that low pressure promoted the production of more extracellular polymeric substances (EPSs) compared to ambient conditions. The results implied that the low pressure environment of 50 kPa in a future lunar base would induce different effects on biological components in a CELSS, which must be considered during the course of designing a future lunar base. The results will be a reference for exploring the response of other biological components, such as plants, microbes, and animals, living in the life support system of a lunar base.

  14. Equipment errors: A prevalent cause for fallacy in blood pressure recording - A point prevalence estimate from an indian health university

    Directory of Open Access Journals (Sweden)

    Badrinarayan Mishra

    2013-01-01

    Full Text Available Background: Blood pressure (BP recording is the most commonly measured clinical parameter. Standing mercury sphygmomanometer is the most widely used equipment to record this. However, recording by sphygmomanometer is subject to observer and instrumental error. The different sources of equipment error are faulty manometer tube calibration, baseline deviations and improper arm bladder cuff dimensions. This is further compounded by a high prevalence of arm bladder miss-cuffing in the target population. Objectives: The study was designed to assess the presence of equipment malcalibrations, cuff miss-matching and their effect on BP recording. Materials and Methods: A cross-sectional check of all operational sphygmomanometers in a health university was carried out for the length of the manometer tube, deviation of resting mercury column from "0" level, the width and length of arm bladder cuff and extent of bladder cuff-mismatch with respect to outpatient attending population. Results: From the total of 50 apparatus selected, 39 (78% were from hospital setups and 11 (22% from pre-clinical departments. A manometer height deficit of 13 mm was recorded in 36 (92.23% of the equipment in hospital and 11 (100% from pre-clinical departments. Instruments from both settings showed significant deviation from recommended dimensions in cuff bladder length, width and length to width ratio (P < 0.001. Significant number of apparatus from hospital setups showed presence of mercury manometer baseline deviation either below or above 0 mmHg at the resting state (χ2 = 5.61, D. F. = 1, P = 0.02. Positive corelationship was observed between manometer height deficit, baseline deviation and width of arm cuff bladder (Pearson correlation, P < 0.05. Bladder cuff mismatching in response to the target population was found at 48.52% for males and 36.76% for females. The cumulative effect of these factors can lead to an error in the range of 10-12 mmHg. Conclusion : Faulty

  15. Solidification and loss of hydrostaticity in liquid media used for pressure measurements

    Science.gov (United States)

    Torikachvili, M. S.; Kim, S. K.; Colombier, E.; Bud'ko, S. L.; Canfield, P. C.

    2015-12-01

    We carried out a study of the pressure dependence of the solidification temperature in nine pressure transmitting media that are liquid at ambient temperature, under pressures up to 2.3 GPa. These fluids are 1:1 isopentane/n-pentane, 4:6 light mineral oil/n-pentane, 1:1 isoamyl alcohol/n-pentane, 4:1 methanol/ethanol, 1:1 FC72/FC84 (Fluorinert), Daphne 7373, isopentane, and Dow Corning PMX silicone oils 200 and 60 000 cS. We relied on the high sensitivity of the electrical resistivity of Ba(Fe1-xRux)2As2 single crystals to the freezing of the pressure media and cross-checked with corresponding anomalies observed in the resistance of the manganin coil that served as the ambient temperature resistive manometer. In addition to establishing the temperature-pressure line separating the liquid (hydrostatic) and frozen (non-hydrostatic) phases, these data permit rough estimates of the freezing pressure of these media at ambient temperature. This pressure establishes the extreme limit for the medium to be considered hydrostatic. For higher applied pressures, the medium has to be treated as non-hydrostatic.

  16. Ankle-brachial pressure index estimated by laser Doppler in patients suffering from peripheral arterial obstructive disease.

    Science.gov (United States)

    Ludyga, Tomasz; Kuczmik, Waclaw B; Kazibudzki, Marek; Nowakowski, Przemyslaw; Orawczyk, Tomasz; Glanowski, Michal; Kucharzewski, Marcin; Ziaja, Damion; Szaniewski, Krzysztof; Ziaja, Krzysztof

    2007-07-01

    Ankle-brachial index (ABI) measurements are widely used for evaluating the functional state of circulation in the lower limbs. However, there is some evidence that the value of ABI does not accurately reflect the degree of walking impairment in symptomatic patients with peripheral arterial obstructive disease (PAOD). We investigated the diagnostic value of ABI estimated by means of laser Doppler flowmetry (IT) for evaluating limb ischemia. We wanted to know whether laser Doppler could be more sensitive than the Doppler method in predicting walking capacity in patients with stable intermittent claudication. We analyzed a group of 30 patients with intermittent claudication (Fontain II, II/III) who were admitted for reconstructive treatment. There were 21 men and 9 women, aged 46-74 (mean 61) years. All patients underwent the treadmill test, and pain-free walking distances were measured. In each patient, we measured ABI using the two different methods: Doppler ultrasound device (ABI-Doppler) and laser Doppler (ABI-laser Doppler). The claudication distances were 25-200 m (mean 73 +/- 50.2 m). ABI-Doppler was 0.2-0.7 (0.582 +/- 0.195). ABI-laser Doppler measurements were 0.581 (+/-0.218). A correlation was found between ABI-Doppler and claudication distance (r = 0.46, P = 0.009). Also, ABI-laser Doppler values significantly correlated with claudication distances (r = 0.536, P = 0.002). The ABI evaluated by laser Doppler correlated well with claudication distances in patients with PAOD. Comparison of Doppler and laser Doppler measurements used for determining ABI showed that both methods have similar predictive power for walking capacity; however, higher correlation was observed between claudication distances and ABI measured by laser Doppler flowmetry. ABI-laser Doppler measurements are easier, are quicker, and seem to be better suited for noncompliant patients. Further investigation should be undertaken to determine whether laser Doppler is superior to the Doppler

  17. Ambient mass spectrometry imaging

    DEFF Research Database (Denmark)

    Janfelt, Christian; Nørgaard, Asger W

    2012-01-01

    Easy ambient sonic spray ionization (EASI) and desorption electrospray ionization (DESI) were used for imaging of a number of samples, including sections of rat brain and imprints of plant material on porous Teflon. A novel approach termed Displaced Dual-mode Imaging was utilized for the direct...

  18. La radioactividad ambiental

    OpenAIRE

    Rafael Núñez-Lagos Roglá

    2011-01-01

    Se explican los conceptos fundamentales relacionados con la radiactividad y se utilizan para describir la radiactividad ambiental. Se explican también los isótopos de largo periodo y las principales familias radioactivas junto con la radiación cósmica y los radionucleidos cosmogénicos.

  19. La radioactividad ambiental

    Directory of Open Access Journals (Sweden)

    Rafael Núñez-Lagos Roglá

    2011-01-01

    Full Text Available Se explican los conceptos fundamentales relacionados con la radiactividad y se utilizan para describir la radiactividad ambiental. Se explican también los isótopos de largo periodo y las principales familias radioactivas junto con la radiación cósmica y los radionucleidos cosmogénicos.

  20. TRAC-PF1/MOD1: an advanced best-estimate computer program for pressurized water reactor thermal-hydraulic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liles, D.R.; Mahaffy, J.H.

    1986-07-01

    The Los Alamos National Laboratory is developing the Transient Reactor Analysis Code (TRAC) to provide advanced best-estimate predictions of postulated accidents in light-water reactors. The TRAC-PF1/MOD1 program provides this capability for pressurized water reactors and for many thermal-hydraulic test facilities. The code features either a one- or a three-dimensional treatment of the pressure vessel and its associated internals, a two-fluid nonequilibrium hydrodynamics model with a noncondensable gas field and solute tracking, flow-regime-dependent constitutive equation treatment, optional reflood tracking capability for bottom-flood and falling-film quench fronts, and consistent treatment of entire accident sequences including the generation of consistent initial conditions. The stability-enhancing two-step (SETS) numerical algorithm is used in the one-dimensional hydrodynamics and permits this portion of the fluid dynamics to violate the material Courant condition. This technique permits large time steps and, hence, reduced running time for slow transients.

  1. Bisulphate-cluster based atmospheric pressure chemical ionization mass spectrometer for ultra-high sensitivity (10 ppq detection of atmospheric amines: proof-of-concept and first ambient data from boreal forest

    Directory of Open Access Journals (Sweden)

    M. Sipilä

    2015-04-01

    Full Text Available Atmospheric amines may play a crucial role in formation of new aerosol particles via nucleation with sulphuric acid. Recent studies have revealed that concentrations below 1 ppt can significantly promote nucleation of sulphuric acid particles. While sulphuric acid detection is relatively straightforward, no amine measurements to date have been able to reach the critical sub-ppt concentration range and atmospheric amine concentrations are in general poorly characterized. In this work we present a proof-of-concept of an instrument capable of detecting dimethyl amine (DMA with concentrations even down to 8 ppq (parts per quadrillion, 0.008 ppt for a 15 min integration time. Detection of ammonia and amines other than dimethyl amine is discussed. We also report results from the first ambient measurements performed in spring 2013 at a boreal forest site. While minute signals from some amines were observed, DMA concentration never exceeded the detection threshold of ambient measurements (20 ppq, suggesting that it is unlikely that nucleation at this location involves DMA.

  2. Impact of mitral E/A ratio on the accuracy of different echocardiographic indices to estimate left ventricular end-diastolic pressure.

    Science.gov (United States)

    Poerner, Tudor C; Goebel, Björn; Kralev, Stefan; Kaden, Jens J; Süselbeck, Tim; Haase, Karl K; Borggrefe, Martin; Haghi, Dariusch

    2007-05-01

    The objective was to determine the influence of left ventricular (LV) inflow pattern on the accuracy of different echocardiographic indices for estimation of LV end-diastolic pressure (LVEDP). Echocardiography with color tissue Doppler imaging (TDI) and LVEDP measurements using fluid-filled catheters were performed in 176 consecutive patients on the same day. Mitral peak diastolic velocities (E, A) and the difference in duration between pulmonary venous retrograde velocity and mitral A-velocity (PV(R)-A) were recorded by pulsed Doppler. Propagation velocity of the early mitral inflow (V(P)) was assessed using color M-mode. Early diastolic longitudinal (E'(lat)) and radial (E'(radial)) velocities of mitral annulus were measured by TDI. Area under ROC curve (AUC) for prediction of elevated LVEDP (> or =15 mm Hg) was computed for each parameter. For E/A > or =1 (98 patients, 46 with elevated LVEDP), the AUC values were: PV(R)-A: 0.914; E/E'(lat): 0.780; E/E'(radial): 0.729; E/V(P): 0.712 (p PV(R)-A reached statistical significance (AUC = 0.893, p PV(R)-A enabled the most accurate noninvasive estimation of LVEDP irrespective of LV filling profile and combined indices E/V(P), E/E'(lat) and E/E'(radial) represent more feasible alternatives for patients with mitral E/A-1.

  3. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation??s (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  4. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation's (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  5. Depth Profiling Ambient Noise in the Deep Ocean

    Science.gov (United States)

    Barclay, David Readshaw

    Deep Sound is an un-tethered, free-falling acoustic platform designed to profile the ambient noise field in the ocean from the surface to a pre-programmed depth, at which point a ballast weight is dropped and the instrument returns to the surface under its own buoyancy. Three iterations of the instrument, Mk I, II and III, have been designed, built and tested, the first two rated to descend to 9 km and the third to a full ocean depth of 11 km. During a deployment of the instrument, vertically and horizontally spaced hydrophones continuously record the ambient noise pressure time series over a large bandwidth (5 Hz -- 40 kHz), returning the power spectral density, vertical and horizontal coherence as a function of depth. Deep Sound Mk I and Mk II have been deployed down to 9 km depth in the Mariana Trench and Mk I has descended three times to 5 km, 5.5 km and 6 km in the Philippine Sea. The data reported here examines the depth-dependence of the power spectrum, vertical coherence and directionality of rain and wind noise in the Philippine Sea. Acoustic estimates of rainfall rates and wind speeds are made from the surface to 5.5 km and 6 km respectively and compared to surface meteorological measurements. The depth-dependence of the accuracy of these estimates is relatively small and found to improve with depth. A coherence fitting procedure is employed to return ambient noise directionality and provide information on the spatial variability of an overhead rainstorm. With moderate 7-10 m/s winds, downward propagating noise from directly overhead dominates the noise field directionality from the surface to 6 km. Using the wind generated surface noise and the depth dependence of the spectral slope over the band 1 -- 10 kHz, the frequency dependence of the absorption due to sea water is estimated and used to infer a mean water column value of pH.

  6. Medio ambiente urbano

    OpenAIRE

    2009-01-01

    El estudio  y análisis  de las interacciones  entre  ambiente  y desarrollo y  su inserción  en los procesos  de  planificación del crecimiento  social y económico  de  los  países  de América Latina, reviste especial interés para proponer alternativas de acción que  conduzcan  al  logro  de  una mejor  calidad de  vida.  El impacto  que las conferencias sobre  el  Medio Ambiente Humano Estocolmo (1972),  Cocoyoc  (1974) o de documentos como "Nuestro Futuro Común" o "Nuestra Propia Agenda" ha...

  7. NIF Ambient Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Noble, C.R.; Hoehler, M.S., S.C. Sommer

    1999-11-29

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B.

  8. Ambient temperature recorder

    Science.gov (United States)

    Russell, Larry D.

    1991-01-01

    A temperature data recorder, designated the Ambient Temperature Recorder (ATR-4), was developed at NASA Ames Research Center to meet particular requirements for space life sciences experiments. The small, self-contained, four-channel, battery-powered device records 32 kilobytes of temperature data over a range of -40 to +60 C at four sampling intervals ranging from 1.875 to 15 minutes. Data is stored in its internal electronic memory for later readout by a personal computer.

  9. Pressure vessel design manual

    CERN Document Server

    Moss, Dennis R

    2013-01-01

    Pressure vessels are closed containers designed to hold gases or liquids at a pressure substantially different from the ambient pressure. They have a variety of applications in industry, including in oil refineries, nuclear reactors, vehicle airbrake reservoirs, and more. The pressure differential with such vessels is dangerous, and due to the risk of accident and fatality around their use, the design, manufacture, operation and inspection of pressure vessels is regulated by engineering authorities and guided by legal codes and standards. Pressure Vessel Design Manual is a solutions-focused guide to the many problems and technical challenges involved in the design of pressure vessels to match stringent standards and codes. It brings together otherwise scattered information and explanations into one easy-to-use resource to minimize research and take readers from problem to solution in the most direct manner possible. * Covers almost all problems that a working pressure vessel designer can expect to face, with ...

  10. Estimation of Temperature, Pressure and Oxygen Fugacity of the Cal-Alkaline Basin-Type Granitoids in the Winneba Area, Ghana

    Directory of Open Access Journals (Sweden)

    Nyarko Saah Esther

    2012-01-01

    Full Text Available In Ghana, the granitoids rocks are in two different groups, thus the basin type granitoid and the belt type granitoids. These granitoids have been studied petrographycally mineralogically and geochemically, especially the belt-type granitoids since it is the major host of gold occurrences in Ghana, however there are little studies on the petrogenesis and emplacement conditions of this important rock. In this paper we present the lacking knowledge on the emplacement conditions (temperature, pressure and the oxygen fugacity of the basin-type granitoids in the winneba area of Ghana.The calc-alkaline basin-type granitoids in the Winneba area is composed of quartz+ plagioclase +potash feldspar+ alkali feldspar+ Biotite+ Hornblende +amphibole+ titanite. The plagioclase composition ranges from Ab58 An1.7 Or0.45 to Ab98 An41 Or41 and mainly in the field of albite and oligoclase. The amphiboles however have a compositional range of Mg/(Mg +Fe ranging from 0.52 to 0.62 and a Si content of 7.1 to 7.4 atom per formula unit (afu. Their end-member compositions in the classification diagram are controlled by Magnesio-Hornblend, tschermakitic-Hornblend, and tschemakite substitution types. Scanning Electron Microscope (SEM analyses of coexisting hornblende and plagioclase (hornblende-plagioclase thermometry, Al content in hornblende (aluminum-in-hornblende barometry and the assemblage titanite-magnetite-quartz were used to constrain the P, T and fO2 during the crystallization of the parent magmas. The estimated temperature indicated an average temperature of crystallization of 677ºC reflecting late crystallization from highly oxidized magma (log fO2 -20 bars.The rocks were emplaced at an average pressure of 2.2 kbars corresponding to approximately 8 km depth of below the crust.

  11. Potential of right to left ventricular volume ratio measured on chest CT for the prediction of pulmonary hypertension: correlation with pulmonary arterial systolic pressure estimated by echocardiography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Heon [Soon Chun Hyang University, Department of Radiology, Bucheon (Korea, Republic of); Kim, Seok Yeon [Seoul Medical Center, Department of Cardiology, Seoul (Korea, Republic of); Lee, Soo Jeong [Terarecon Korea, Seoul (Korea, Republic of); Kim, Jae Kyun [Chung-Ang University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Reddy, Ryan P.; Schoepf, U.J. [Medical University of South Carolina, Department of Radiology and Radiological Science and Division of Cardiology, Department of Medicine, Charleston, SC (United States)

    2012-09-15

    To investigate the correlation of right ventricular (RV) to left ventricular (LV) volume ratio measured by chest CT with pulmonary arterial systolic pressure (PASP) estimated by echocardiography. 104 patients (72.47 {+-} 13.64 years; 39 male) who had undergone chest CT and echocardiography were divided into two groups (hypertensive and normotensive) based upon an echocardiography-derived PASP of 25 mmHg. RV to LV volume ratios (RV{sub V}/LV{sub V}) were calculated. RV{sub V}/LV{sub V} was then correlated with PASP using regression analysis. The Area Under the Curve (AUC) for predicting pulmonary hypertension on chest CT was calculated. In the hypertensive group, the mean PASP was 46.29 {+-} 14.42 mmHg (29-98 mmHg) and there was strong correlation between the RV{sub V}/LV{sub V} and PASP (R = 0.82, p < 0.001). The intraobserver and interobserver correlation coefficients for RV{sub V}/LV{sub V} were 0.990 and 0.892. RV{sub V}/LV{sub V} was 1.01 {+-} 0.44 (0.51-2.77) in the hypertensive and 0.72 {+-} 0.14 (0.52-1.11) in the normotensive group (P <0.05). With 0.9 as the cutoff for RV{sub V}/LV{sub V}, sensitivity and specificity for predicting pulmonary hypertension over 40 mmHg were 79.5 % and 90 %, respectively. The AUC for predicting pulmonary hypertension was 0.87 RV/LV volume ratios on chest CT correlate well with PASP estimated by echocardiography and can be used to predict pulmonary hypertension over 40 mmHg with high sensitivity and specificity. (orig.)

  12. Numerical Analysis of Exergy for Air-Conditioning Influenced by Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Jing-Nang Lee

    2014-07-01

    Full Text Available The article presents numerical analysis of exergy for air-conditioning influenced by ambient temperature. The model of numerical simulation uses an integrated air conditioning system exposed in varied ambient temperature to observe change of the four main devices, the compressor, the condenser, the capillary, and the evaporator in correspondence to ambient temperature. The analysis devices of the four devices’s exergy influenced by the varied ambient temperature and found that the capillary has unusual increasing exergy loss vs. increasing ambient temperature in comparison to the other devices. The result shows that reducing exergy loss of the capillary influenced by the ambient temperature is the key for improving working efficiency of an air-conditioning system when influence of the ambient temperature is considered. The higher ambient temperature causes the larger pressure drop of capillary and more exergy loss.

  13. On Better Estimating and Normalizing the Relationship between Clinical Parameters: Comparing Respiratory Modulations in the Photoplethysmogram and Blood Pressure Signal (DPOP versus PPV

    Directory of Open Access Journals (Sweden)

    Paul S. Addison

    2015-01-01

    Full Text Available DPOP (ΔPOP or Delta-POP is a noninvasive parameter which measures the strength of respiratory modulations present in the pulse oximeter waveform. It has been proposed as a noninvasive alternative to pulse pressure variation (PPV used in the prediction of the response to volume expansion in hypovolemic patients. We considered a number of simple techniques for better determining the underlying relationship between the two parameters. It was shown numerically that baseline-induced signal errors were asymmetric in nature, which corresponded to observation, and we proposed a method which combines a least-median-of-squares estimator with the requirement that the relationship passes through the origin (the LMSO method. We further developed a method of normalization of the parameters through rescaling DPOP using the inverse gradient of the linear fitted relationship. We propose that this normalization method (LMSO-N is applicable to the matching of a wide range of clinical parameters. It is also generally applicable to the self-normalizing of parameters whose behaviour may change slightly due to algorithmic improvements.

  14. Ambient og intelligent teknologi

    DEFF Research Database (Denmark)

    Andersen, Peter Bøgh

     Dette notat handler om hvordan humanistisk og samfundsfaglig forskning i øjeblikket nyttiggøres ved udformning af IKT-anvendelser, der er indlejret i vor dagligdag i den forstand, at de indgår som et element i de aktiviteter, vi foretager på arbejdet eller i fritiden. Sådanne anvendelser kaldes ...... undertiden ambiente – noget der omslutter os på alle sider. Rapporten peger også på virkemidler som kan forbedre og øge en humanistisk og samfundsfaglig forskningsindsats....

  15. AOX y medio ambiente.

    OpenAIRE

    1996-01-01

    Los productos organohalogenados son muy utilizados por la industria y su presencia en el medio ambiente está siendo controlada. En los últimos años se han desarrollado varias técnicas de detección, siendo desde finales de los 80 los AOX (adsorbable organic halogens) uno de los parámetros sobre los que se han realizado más estudios. En muchos paises de la Unión Europea y en E.E.U.U. de América, la presencia de compuestos organohalogenados en aguas continentales y suelos está legislada indicand...

  16. Photosynthesis of H2O2 and O3 in ASW with ambient O2

    Science.gov (United States)

    Shi, J.; Raut, U.; Loeffler, M.; Kim, J.; Baragiola, R. A.

    2009-12-01

    Tenuous O2 atmospheres are known to exist around icy satellites such as Europa and Ganymede and around Saturn’s rings and satellites [1,2]. These faint atmospheres with pressures estimated in 10-3 to 10-8 mbar range [2] are thought to be produced from photolysis and radiolysis of surface ice. In efforts to simulate closely the conditions on icy satellites and grains, ion irradiation of laboratory ices have been performed while maintaining an ambient O2 pressure in recent experiments, which lead to the discovery of the ion-induced O2 adsorption [3]. In the experiments presented here, we investigated the effect of UV photolysis on the ice films in the presence of ambient O2 pressure. Water ice films vapor-deposited between 40 and 100 K were irradiated using 193 nm photons from an ArF Excimer laser, under a constant ambient gas pressure of 7x10-7 mbar. The changes in the film during laser irradiation were monitored using infrared spectroscopy and quartz crystal microgravimetry. At 50 K, we exposed our film to photolysis under ambient pressure of different gas species: Ar, N2 and O2. Interestingly we find enhanced gas absorption only in the presence of ambient O2. In addition, we find that the dangling bond IR absorption disappears, indicating the collapse of micropores. We note that the dangling bond absorption decreases only ~10% in an ice film subject to UV irradiation in the absence of ambient gas, which suggests that the enhanced O2 absorption is not due to gas trapping during compaction [3], but to photo-chemical reactions between OH and transiently adsorbed O2, forming H2O2 and O3, which we detected with IR spectroscopy. We observed that the formation of these two products increases below 50 K, which is explained by increased O2 adsorption at decreasing temperature. Interestingly, if we increase the ambient O2 pressure, then we can increase the maximum temperature for which we can make O3. O3 has not been identified in photolysis of laboratory ice and only

  17. Comparison of noninvasive pulse transit time estimates as markers of blood pressure using invasive pulse transit time measurements as a reference.

    Science.gov (United States)

    Gao, Mingwu; Olivier, N Bari; Mukkamala, Ramakrishna

    2016-05-01

    Pulse transit time (PTT) measured as the time delay between invasive proximal and distal blood pressure (BP) or flow waveforms (invasive PTT [I-PTT]) tightly correlates with BP PTT estimated as the time delay between noninvasive proximal and distal arterial waveforms could therefore permit cuff-less BP monitoring. A popular noninvasive PTT estimate for this application is the time delay between ECG and photoplethysmography (PPG) waveforms (pulse arrival time [PAT]). Another estimate is the time delay between proximal and distal PPG waveforms (PPG-PTT). PAT and PPG-PTT were assessed as markers of BP over a wide physiologic range using I-PTT as a reference. Waveforms for determining I-PTT, PAT, and PPG-PTT through central arteries were measured from swine during baseline conditions and infusions of various hemodynamic drugs. Diastolic, mean, and systolic BP varied widely in each subject (group average (mean ± SE) standard deviation between 25 ± 2 and 36 ± 2 mmHg). I-PTT correlated well with all BP levels (group average R(2) values between 0.86 ± 0.03 and 0.91 ± 0.03). PPG-PTT also correlated well with all BP levels (group average R(2) values between 0.81 ± 0.03 and 0.85 ± 0.02), and its R(2) values were not significantly different from those of I-PTT PAT correlated best with systolic BP (group average R(2) value of 0.70 ± 0.04), but its R(2) values for all BP levels were significantly lower than those of I-PTT (P < 0.005) and PPG-PTT (P < 0.02). The pre-ejection period component of PAT was responsible for its inferior correlation with BP In sum, PPG-PTT was not different from I-PTT and superior to the popular PAT as a marker of BP.

  18. Crisis ambiental y cristianismo

    Directory of Open Access Journals (Sweden)

    Felipe Cárdenas

    2008-01-01

    Full Text Available En el artículo se identifican y reconocen algunas opciones que se pueden desarrollar en el cristianismo en relación con la problemática ambiental. Se aborda el dilema bíblico suscitado por interpretaciones antiecológicas y ecológicas. Con base en una lectura de la Biblia, de testimonios cristianos, y en una rememoria de estructuras institucionales, como la parroquia, se analiza el valor que tiene el mensaje cristiano en lo referido a la mitigación de la crisis ambiental.This article identifies and recognizes some options that can be developed in Christianity in relation to the environmental problem. It starts by analyzing the biblical dilemma provoked by both ecological and antiecological interpretations. Based on a reading of the Bible, testimonies from Christians and with a rememory of institutional structures, like the parish, the valué of the Christian message for mitigating the environmental crisis is analyzed.

  19. Types for BioAmbients

    Directory of Open Access Journals (Sweden)

    Sara Capecchi

    2010-02-01

    Full Text Available The BioAmbients calculus is a process algebra suitable for representing compartmentalization, molecular localization and movements between compartments. In this paper we enrich this calculus with a static type system classifying each ambient with group types specifying the kind of compartments in which the ambient can stay. The type system ensures that, in a well-typed process, ambients cannot be nested in a way that violates the type hierarchy. Exploiting the information given by the group types, we also extend the operational semantics of BioAmbients with rules signalling errors that may derive from undesired ambients' moves (i.e. merging incompatible tissues. Thus, the signal of errors can help the modeller to detect and locate unwanted situations that may arise in a biological system, and give practical hints on how to avoid the undesired behaviour.

  20. Types for BioAmbients

    CERN Document Server

    Capecchi, Sara; 10.4204/EPTCS.19.7

    2010-01-01

    The BioAmbients calculus is a process algebra suitable for representing compartmentalization, molecular localization and movements between compartments. In this paper we enrich this calculus with a static type system classifying each ambient with group types specifying the kind of compartments in which the ambient can stay. The type system ensures that, in a well-typed process, ambients cannot be nested in a way that violates the type hierarchy. Exploiting the information given by the group types, we also extend the operational semantics of BioAmbients with rules signalling errors that may derive from undesired ambients' moves (i.e. merging incompatible tissues). Thus, the signal of errors can help the modeller to detect and locate unwanted situations that may arise in a biological system, and give practical hints on how to avoid the undesired behaviour.

  1. Non-invasive estimation of intracranial pressure. MR-based evaluation in children with hydrocephalus; Nichtinvasive Bestimmung des intrakraniellen Drucks. MR-basierte Untersuchung bei Kindern mit Hydrozephalus

    Energy Technology Data Exchange (ETDEWEB)

    Muehlmann, M.; Steffinger, D.; Ertl-Wagner, B.; Koerte, I.K. [Ludwig-Maximilians-Universitaet Muenchen, Institut fuer Klinische Radiologie, Muenchen (Germany); Peraud, A. [Ludwig-Maximilians-Universitaet Muenchen, Abteilung fuer Neurochirurgie, Muenchen (Germany); Lehner, M. [Dr. von Haunersches Kinderspital, Ludwig-Maximilians-Universitaet Muenchen, Abteilung fuer Kinderchirurgie, Muenchen (Germany); Heinen, F.; Alperin, N. [University Miami, Department of Radiology, Miller School of Medicine, Miami (United States)

    2012-09-15

    The intracranial pressure (ICP) is a crucially important parameter for diagnostic and therapeutic decision-making in patients with hydrocephalus. So far there is no standard method to non-invasively assess the ICP. Various approaches to obtain the ICP semi-invasively or non-invasively are discussed and the clinical application of a magnetic resonance imaging (MRI)-based method to estimate ICP (MR-ICP) is demonstrated in a group of pediatric patients with hydrocephalus. Arterial inflow, venous drainage and craniospinal cerebrospinal fluid (CSF) flow were quantified using phase-contrast imaging to derive the MR-ICP. A total of 15 patients with hydrocephalus (n=9 treated with shunt placement or ventriculostomy) underwent MRI on a 3 T scanner applying retrospectively-gated cine phase contrast sequences. Of the patients six had clinical symptoms indicating increased ICP (age 2.5-14.61 years, mean 7.4 years) and nine patients had no clinical signs of elevated ICP (age 2.1-15.9 years; mean 9.8 years; all treated with shunt or ventriculostomy). Median MR-ICP in symptomatic patients was 24.5 mmHg (25th percentile 20.4 mmHg; 75th percentile 44.6 mmHg). Median MR-ICP in patients without acute signs of increased ICP was 9.8 mmHg (25th percentile 8.6 mmHg; 75th percentile 11.4 mmHg). Group differences were significant (p < 0.001; Mann-Whitney U-test). The MR-ICP technique is a promising non-invasive tool for estimating ICP. Further studies in larger patient cohorts are warranted to investigate its application in children with hydrocephalus. (orig.) [German] Der intrakranielle Druck (''intracranial pressure'' - ICP) ist ein entscheidender Parameter bei der Diagnostik, Therapie und Verlaufsbeurteilung von Patienten mit Hydrozephalus. Derzeit gibt es keine radiologische Standardmethode, um den intrakraniellen Druck quantitativ zu bestimmen. Methoden zur invasiven und nichtinvasiven Einschaetzung des ICP werden diskutiert und die Anwendung eines MR

  2. Reforma constitucional y ambiente

    Directory of Open Access Journals (Sweden)

    Teodoro Bustamante

    2013-09-01

    Full Text Available América Latina está atravesada por una ola de reformas constitucionales. Sus causas, las expectativas que ellas despiertan, los riesgos que se han asociado al proceso de lucha política en su entorno, son temas de un análisis fundamentalmente político; pero hay algunos aspectos en los cuales ese debate tiene una directa repercusión sobre el tema ambiental. En el caso del Ecuador, esto se refleja en el hecho de que una de las innovaciones que se proponen, se refieren a una nueva forma de abordar los temas ambientales, básicamente se establecen Derechos de la Naturaleza.

  3. Local Ambient Seismic Noise Survey in Dixie Valley, NV for Engineered Geothermal System Favorability Assessment

    Science.gov (United States)

    Tibuleac, I. M.; Iovenitti, J. L.; von Seggern, D. H.; Sainsbury, J.

    2013-12-01

    The primary objective of this study is to develop and test the seismic component of a calibrated exploration method that integrated geological, geophysical, and geochemical data to identify potential drilling targets for Engineered Geothermal Systems (EGS). In exploring for EGS sites, the selection criteria identified by the AltaRock Energy, Inc. (AltaRock) and University of Nevada, Reno teams are, in order of importance, (1) temperature greater than 200C at 1.5 km depth, (2) rock type at the depth of interest (porous rocks at 1-3 km); and (3) favorable stress regime (tensional environment). To improve spatial resolution, a dense seismic array (21 three-component, broadband sensors, with an overall array aperture of 45km) was installed in two deployments in Dixie Valley, NV, each deployment having a three-month duration Ambient seismic noise and signal were used to retrieve inter-station and same-station Green's Functions (GFs), to be used for subsurface imaging. We used ambient seismic noise interferometry to extract GFs from crosscorrelation of continuous records. An innovative aspect of the seismic work was estimating the receiver functions beneath the stations using noise auto-correlation which was used to image the substructure. We report results of applying the technique to estimate a P/S velocity model from the GF surface wave components and from the GF body-wave reflection component, retrieved from ambient noise and signal cross-correlation and auto-correlation beams. We interpret our results in terms of temperature, pressure and rock composition. The estimated seismic velocity model capability to infer temperature is statistically assessed, in combination with other geophysical technique results.

  4. Energy requirements for CO2 capture from ambient air (DAC) competitive with capture from flue-gas (PCC)

    Science.gov (United States)

    Meinrenken, Christoph

    2015-03-01

    Capture of CO2, whether from a flue gas source (PCC) or from distributed sources via ambient air (DAC), is a key enabling technology to provide carbon for sustainable synthetic energy carriers such as solar fuels. Based on thermodynamic minimum considerations, DAC is often expected to require about 3 times more energy (per ton CO2 captured) than PCC because CO2 in ambient air is more dilute. Here, we calculate the energy required for a humidity swing-based DAC installation that uses an anionic exchange resin as sorbent. The calculation uses recently measured equilibrium CO2 loadings of the sorbent as function of partial CO2 pressure, temperature, and humidity. We calculate the installation's electricity consumption to be about 45 kJ per mole of pure CO2 at 1 bar (scenario-dependent). Furthermore, we estimate the amount of heat provided by ambient air and thus provide context of the overall energy and entropy balance and thermodynamic minimum views. The electricity consumption is competitive with typical parasitic loads of PCC-equipped coal-fired power plants (40-50 kJ per mole at same pressure) and significantly lower than predicted for other DAC installations such as Na(OH) sorbent-based systems. Our analyses elucidate why DAC is not always more energy-intensive that PCC, thus alleviating often cited concerns of significant cost impediments. Financial support by ABB for research presented herein is gratefully acknowledged.

  5. CCN activation of ambient and "synthetic ambient" urban aerosol

    Science.gov (United States)

    Burkart, Julia; Reischl, Georg; Steiner, Gerhard; Bauer, Heidi; Leder, Klaus; Kistler, Magda; Puxbaum, Hans; Hitzenberger, R.

    2013-05-01

    In this study, the Cloud Condensation Nuclei (CCN) activation properties of the urban aerosol in Vienna, Austria, were investigated in a long term (11 month) field study. Filter samples of the aerosol below 100 nm were taken in parallel to these measurements, and later used to generate "synthetic ambient" aerosols. Activation parameters of this "synthetic ambient" aerosol were also obtained. Hygroscopicity parameters κ [1] were calculated both for the urban and the "synthetic ambient" aerosol and also from the chemical composition. Average κ for the "synthetic ambient" aerosol ranged from 0.20 to 0.30 with an average value of 0.24, while the κ from the chemical composition of this "synthetic ambient" aerosol was significantly higher (average 0.43). The full results of the study are given elsewhere [2,3].

  6. In Situ Observations of Thermoreversible Gelation and Phase Separation of Agarose and Methylcellulose Solutions under High Pressure.

    Science.gov (United States)

    Kometani, Noritsugu; Tanabe, Masahiro; Su, Lei; Yang, Kun; Nishinari, Katsuyoshi

    2015-06-04

    Thermoreversible sol-gel transitions of agarose and methylcellulose (MC) aqueous solutions on isobaric cooling or heating under high pressure up to 400 MPa have been investigated by in situ observations of optical transmittance and falling-ball experiments. For agarose, which undergoes the gelation on cooling, the application of pressure caused a gradual rise in the cloud-point temperature over the whole pressure range examined, which is almost consistent with the pressure dependence of gelling temperature estimated by falling-ball experiments, suggesting that agarose gel is stabilized by compression and that the gelation occurs nearly in parallel with phase separation under ambient and high-pressure conditions. For MC, which undergoes the gelation on heating, the cloud-point temperature showed a slight rise with an initial elevation of pressure up to ∼150 MPa, whereas it showed a marked depression above 200 MPa. In contrast, the gelling temperature of MC, which is nearly identical to the cloud-point temperature at ambient pressure, showed a monotonous rise with increasing pressure up to 350 MPa, which means that MC undergoes phase separation prior to gelation on heating under high pressure above 200 MPa. Similar results were obtained for the melting process of MC gel on cooling. The unique behavior of the sol-gel transition of MC under high pressure has been interpreted in terms of the destruction of hydrophobic hydration by compression.

  7. Foro Ambiental : CEDENMA, Asamblea Constituyente

    Directory of Open Access Journals (Sweden)

    Anne-Lise Naizot

    2013-09-01

    Full Text Available Resumen de la Mesa redonda: Orientaciones de la nueva Constitución ecuatoriana en materia ambiental: ¿avances o retrocesos en relación con el marco político y filosófico ambiental vigente en algunos países de la región?

  8. 反应堆退役压力容器放射性活度估算方法%Method for Estimation of Activity in Decommissioned Nuclear Reactor Pressure Vessel

    Institute of Scientific and Technical Information of China (English)

    郭武仁; 林晓玲; 郑宁宁

    2011-01-01

    The theoretical calculation and experimental measurement methods for estimation of activity in the decommissioned nuclear reactor pressure vessel were introduced. The physical estimation model was described,and Monte Carlo compute code and 0RIGEN2 code were recommended to be employed for the calculation of the neutron flux and activity in the reactor pressure vessel. Two methods commonly used for determining the activity in the reactor pressure vessel were introduced in detail,I.e.,sampling from the reactor pressure vessel and from the irradiation tube. The neutron flux profile was established to predict the activity in the reactor pressure vessel.%介绍了反应堆退役压力容器放射性活度估算的理论计算和实验测定方法.描述了物理估算模型,推荐采用蒙特卡罗程序和ORIGEN2程序分别计算中子通量密度和放射性活度.对确定压力容器的放射性活度时经常使用的两种方法(压力容器直接取样分析和对辐照监督管取样分析)做了详细介绍.建立了推算压力容器的放射性活度中子通量密度比例曲线.

  9. Trapping of cubic ZnO nanocrystallites at ambient conditions

    DEFF Research Database (Denmark)

    Decremps, F.; Pellicer-Porres, J.; Datchi, F.

    2002-01-01

    Dense powder of nanocrystalline ZnO has been recovered at ambient conditions in the metastable cubic structure after a heat treatment at high pressure (15 GPa and 550 K). Combined x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) experiments have been performed to probe both long-ra...

  10. Method for estimating critical properties of heavy compounds suitable for cubic equations of state and its application to the prediction of vapor pressures

    DEFF Research Database (Denmark)

    Kontogeorgis, Georgios; Ioannis, Smirlis; Iakovos, Yakoumis

    1997-01-01

    Cubic equations of state (EoS) are often used for correlating and predicting phase equilibria. Before extending any EoS to mixtures, reliable vapor-pressure prediction is essential. This requires experimental, if possible, critical temperatures T-c, pressures P-c, and acentric factor omega...

  11. Ambient Response Analysis Modal Analysis for Large Structures

    DEFF Research Database (Denmark)

    Brincker, Rune; Andersen, Palle

    1999-01-01

    In this paper an outline is given of the basic ideas in ambient respons analysis, i.e. when modal analyses is performed on systems based on output only. Some of the most known techniques are briefly introduced, and the basic problems discussed. The introduced techniques are the frequency domain...... based peak-picking methods, the polyreference LSCE method, the stochastic subspace method for estimation of state space systems and the prediction error method for estimation of Auto-Regressive Moving Average Vector models. The techniques are illustrated on an example of ambient response measurments...

  12. Pressurized air cathodes for enhanced stability and power generation by microbial fuel cells

    Science.gov (United States)

    He, Weihua; Yang, Wulin; Tian, Yushi; Zhu, Xiuping; Liu, Jia; Feng, Yujie; Logan, Bruce E.

    2016-11-01

    Large differences between the water and air pressure in microbial fuel cells (MFCs) can deform and damage cathodes. To avoid deformation, the cathode air pressure was controlled to balance pressure differences between the air and water. Raising the air pressures from 0 to 10 kPa at a set cathode potential of -0.3 V (versus Ag/AgCl) enhanced cathode performance by 17%, but pressures ≥25 kPa decreased current and resulted in air leakage into the solution. Matching the air pressure with the water pressure avoided cathode deformation and improved performance. The maximum power density increased by 15%, from 1070 ± 20 to 1230 ± 70 mW m-2, with balanced air and water pressures of 10-25 kPa. Oxygen partial pressures ≥12.5 kPa in the cathode compartment maintained the oxygen reduction rate to be within 92 ± 1% of that in ambient air. The use of pressurized air flow through the cathode compartments can enable closer spacing of the cathodes compared to passive gas transfer systems, which could make the reactor design more compact. The energy cost of pressurizing the cathodes was estimated to be smaller than the increase in power that resulted from the use of pressurized cathodes.

  13. Estimación de la exposición al humo ambiental de tabaco: revisión de cuestionarios utilizados en España Estimation of environmental tobacco smoke exposure: review of questionnaires used in Spain

    Directory of Open Access Journals (Sweden)

    Manel Nebot

    2011-08-01

    Full Text Available Introducción: En los últimos años, las encuestas de salud y los estudios epidemiológicos sobre el tabaquismo han incorporado preguntas sobre la exposición al humo ambiental de tabaco, aunque no existe un cuestionario estandarizado. Métodos: Entre enero y mayo de 2008 se revisaron las encuestas que contenían preguntas sobre exposición a tabaquismo pasivo realizadas en España desde las administraciones públicas, las sociedades científicas y organismos de investigación. Se han revisado los literales, que se han clasificado según tipo de estudio, población diana, ámbito geográfico y lugar de exposición. Resultados: Se identificaron 27 encuestas que incluían tabaquismo pasivo. La mayoría correspondían a encuestas de salud (81,5% e iban dirigidas a población general (70,4%. El ámbito geográfico más común era el autonómico (48,1% y el lugar de exposición más común el hogar (88,9%. Discusión: Los resultados muestran una enorme variabilidad en las preguntas utilizadas. Es necesario homogeneizar las preguntas sobre exposición al tabaquismo pasivo si queremos comparar los resultados.Introduccion: In the last few years, health surveys and epidemiological studies on smoking have introduced questions on environmental tobacco smoke (ETS exposure. However, a standardized questionnaire is lacking. Methods: Between January and May 2008, we reviewed surveys containing items on ETS exposure carried out in Spain by public administrations, scientific societies and research institutes. The wording of the questions was reviewed and classified according to the study type, target population, geographical setting and place of exposure. Results: We identified 27 surveys that included questions on passive smoking. Most were health surveys (81.5% and were aimed at the general population (70.4%. The most frequent geographical setting consisted of autonomous regions (48.1% and the most common place of exposure was the home (88.9% Discussion: The

  14. Cross-correlations of ambient noise recorded by accelerometers.

    Science.gov (United States)

    Rábade García, S. E.; Ramirez-Guzman, L.

    2014-12-01

    We investigate the ambient noise cross-correlations obtained by using properly corrected accelerometric recordings, and determine velocity structure in central Mexico based on a dispersion analysis. The data used comprise ten months of continuous recordings - from April 2013 to January 2014 - of ambient seismic noise at stations operated by the National Seismological Service of Mexico and the Engineering Strong Ground Motion Network of the National Autonomous University of Mexico (UNAM). The vertical component of ambient noise was base-line corrected, filtered, and properly integrated before extracting Green's functions (GF), which were compared successfully against GF obtained using recordings from broadband velocity sensors. In order to obtain dispersion curves, we estimated group and phase velocities applying the FTAN analysis technique and obtained s-wave velocity profiles at selected regions. We conclude and highlight that the use of widely deployed accelerographs to conduct regional studies using ambient noise tomography is feasible

  15. Wind turbine sound pressure level calculations at dwellings.

    Science.gov (United States)

    Keith, Stephen E; Feder, Katya; Voicescu, Sonia A; Soukhovtsev, Victor; Denning, Allison; Tsang, Jason; Broner, Norm; Leroux, Tony; Richarz, Werner; van den Berg, Frits

    2016-03-01

    This paper provides calculations of outdoor sound pressure levels (SPLs) at dwellings for 10 wind turbine models, to support Health Canada's Community Noise and Health Study. Manufacturer supplied and measured wind turbine sound power levels were used to calculate outdoor SPL at 1238 dwellings using ISO [(1996). ISO 9613-2-Acoustics] and a Swedish noise propagation method. Both methods yielded statistically equivalent results. The A- and C-weighted results were highly correlated over the 1238 dwellings (Pearson's linear correlation coefficient r > 0.8). Calculated wind turbine SPLs were compared to ambient SPLs from other sources, estimated using guidance documents from the United States and Alberta, Canada.

  16. Conversion of Dynamic High Pressures from Air to Water for a Spherical TNT Charge

    Directory of Open Access Journals (Sweden)

    A. K. Sharma

    1996-01-01

    Full Text Available A numerical method has been applied to convert the dynamic high pressures from air-to-water for a spherical TNT charge. Standard equation of scaling law in air for TNT has been utilised to make the necessary conversions. The investigations have been made by taking into consideration the ambient pressure values for the two media. The calculations have been performed under the scaled distances to get better results. Experimental measurements using indigenous blast pressure gauge have been undertaken by detonating spherical charges of TNT under the same scaled distances in water to check the correctness of results and direct application of this method. A fairly close agreement between the theoretically computed and the experimental values of the dynamic high pressures shows the practical utility of this approach in that it enables an estimate of the experimental shock wave pressures, without conducting underwater experiments.

  17. Left ventricular filling pressure estimation at rest and during exercise in patients with severe aortic valve stenosis: comparison of echocardiographic and invasive measurements

    DEFF Research Database (Denmark)

    Dalsgaard, Morten; Kjaergaard, Jesper; Pecini, Redi;

    2009-01-01

    BACKGROUND: The Doppler index of left ventricular (LV) filling (E/e') is recognized as a noninvasive measure for LV filling pressure at rest but has also been suggested as a reliable measure of exercise-induced changes. The aim of this study was to investigate changes in LV filling pressure......, measured invasively as pulmonary capillary wedge pressure (PCWP), at rest and during exercise to describe the relation with E/e' in patients with severe aortic stenosis. METHODS: Twenty-eight patients with an aortic valve areas

  18. Sociología ambiental

    OpenAIRE

    Domínguez Gómez, José Andrés; Aledo Tur, Antonio

    2001-01-01

    Este libro pretende ser un manual para los alumnos de las licenciaturas de sociología, ecología, ciencias ambientales o economía y profesionales de esas ramas que estén interesados en el estudio de las relaciones entre medio ambiente y sociedad desde una aproximación sociológica. El manual está divido en dos partes. La primera desarrolla las principales teorías sociológicas sobre el medio ambiente, así como el heterogéneo pensamiento ambiental. La segunda parte, ofrece capítulos diversos en l...

  19. Ciencia, cultura y medio ambiente

    OpenAIRE

    Ángel Maya, Augusto

    1991-01-01

    La crisis ambiental no es un fenómeno exclusivamente de orden tecnológico. Interroga por igual las organizaciones socio-políticas y los instrumentos científicos para el estudio de la realidad: posiblemente uno de los obstáculos mayores para el encuentro de soluciones adecuadas a la crisis ambiental, radica no en deficiencias de orden técnico, sino en la incapacidad de los instrumentos teóricos para entenderla. La crisis del medio ambiente ha puesto en claro la ambivalencia no sólo de la organ...

  20. La crisis del medio ambiente

    OpenAIRE

    Juan Carlos Quintero Vélez; Clemencia Camacho Delgado

    2013-01-01

    Este artículo, introducción al tema del medio ambiente, pretende proporcionar conceptos básicos para analizar y dimensionar el impacto que genera el hombre sobre los sistemas que soportan la vida. Para entender estos problemas, es indispensable partir de un análisis básico de la relación entre el hombre actual, su medio ambiente, sus necesidades y sus actividades. El autor revisa los antecedentes, las causas y las consecuencias de la crisis ambiental internacional, e intenta dar explicación a...

  1. Albedo and estimates of net radiation for green beans under polyethylene cover and field conditions Albedo e estimativas do saldo de radiação em feijão-vagem sob cobertura de plástico e ambiente externo

    Directory of Open Access Journals (Sweden)

    José Leonaldo de Souza

    1999-10-01

    Full Text Available This paper describes the albedo (r and estimates of net radiation and global solar irradiance for green beans crop (Phaseolus vulgaris L., cultivated in greenhouse with cover of polyethylene and field conditions, in Botucatu, SP, Brazil (22º 54' S; 48º 27' W; 850 m. The solar global irradiance (Rg and solar reflected radiation (Rr were used to estimate the albedo through the ratio between Rr and Rg. The diurnal curves of albedo were obtained for days with clear sky and partially cloudy conditions, for different phenological stages of the crop. The albedo ranged with the solar elevation, the environment and the phenological stages. The cloudiness range have almost no influence on the albedo diurnal amount. The estimation of radiation were made by linear regression, using the global solar irradiance (Rg and net short-waves radiation (Rc as independent variables. All estimates of radiation showed better adjustment for specific phenological periods compared to the entire crop growing cycle. The net radiation in the greenhouse has been estimated by the global solar irradiance measured at field conditions.Este trabalho objetivou determinar o albedo (r no espectro solar e estimar o saldo de radiação, em ambientes cultivados com feijão-vagem (Phaseolus vulgaris L., em condições de campo e em casa de vegetação com cobertura de polietileno, em Botucatu, SP, (22º 54' S; 48º 27' W; 850 m. A irradiância solar global (Rg e a radiação solar refletida (Rr foram utilizadas na determinação do albedo através da razão entre Rr e Rg. Curvas diurnas de r foram traçadas para dias com céu parcialmente nublado e claro, em fases fenológicas da cultura. Os valores do albedo diurno, obtidos através dos totais de radiações, foram utilizados para analisar a variação desse índice durante o ciclo da cultura, nos dois ambientes. O albedo variou com a elevação solar, o ambiente e as fases fenológicas da cultura. A variação de nebulosidade

  2. Modal Identification from Ambient Responses Using Frequency Domain Decomposition

    DEFF Research Database (Denmark)

    Brincker, Rune; Zhang, Lingmi; Andersen, Palle

    2000-01-01

    In this paper a new frequency domain technique is introduced for the modal identification from ambient responses, i.e. in the case where the modal parameters must be estimated without knowing the input exciting the system. By its user friendliness the technique is closely related to the classical...

  3. Modal Identification from Ambient Responses using Frequency Domain Decomposition

    DEFF Research Database (Denmark)

    Brincker, Rune; Zhang, L.; Andersen, P.

    2000-01-01

    In this paper a new frequency domain technique is introduced for the modal identification from ambient responses, ie. in the case where the modal parameters must be estimated without knowing the input exciting the system. By its user friendliness the technique is closely related to the classical...

  4. Antimicrobial Applications of Ambient--Air Plasmas

    Science.gov (United States)

    Pavlovich, Matthew John

    The emerging field of plasma biotechology studies the applications of the plasma phase of matter to biological systems. "Ambient-condition" plasmas created at or near room temperature and atmospheric pressure are especially promising for biomedical applications because of their convenience, safety to patients, and compatibility with existing medical technology. Plasmas can be created from many different gases; plasma made from air contains a number of reactive oxygen and nitrogen species, or RONS, involved in various biological processes, including immune activity, signaling, and gene expression. Therefore, ambient-condition air plasma is of particular interest for biological applications. To understand and predict the effects of treating biological systems with ambient-air plasma, it is necessary to characterize and measure the chemical species that these plasmas produce. Understanding both gaseous chemistry and the chemistry in plasma-treated aqueous solution is important because many biological systems exist in aqueous media. Existing literature about ambient-air plasma hypothesizes the critical role of reactive oxygen and nitrogen species; a major aim of this dissertation is to better quantify RONS by produced ambient-air plasma and understand how RONS chemistry changes in response to different plasma processing conditions. Measurements imply that both gaseous and aqueous chemistry are highly sensitive to operating conditions. In particular, chemical species in air treated by plasma exist in either a low-power ozone-dominated mode or a high-power nitrogen oxide-dominated mode, with an unstable transition region at intermediate discharge power and treatment time. Ozone (O3) and nitrogen oxides (NO and NO2, or NOx) are mutually exclusive in this system and that the transition region corresponds to the transition from ozone- to nitrogen oxides-mode. Aqueous chemistry agrees well with to air plasma chemistry, and a similar transition in liquid-phase composition

  5. Setting thresholds to varying blood pressure monitoring intervals differentially affects risk estimates associated with white-coat and masked hypertension in the population

    DEFF Research Database (Denmark)

    Asayama, Kei; Thijs, Lutgarde; Li, Yan;

    2014-01-01

    1.76 to 2.03. In conclusion, identification of truly low-risk white-coat hypertension requires setting thresholds simultaneously to 24 hours, daytime, and nighttime blood pressure. Although any time interval suffices to diagnose masked hypertension, as proposed in current guidelines, full 24-hour...

  6. Avaliação de fatores de ambiente e estimativas de parâmetros genéticos para a característica dias para o parto na raça Nelore Environmental effects and genetic parameters estimates for days to calving in Nelore cattle

    Directory of Open Access Journals (Sweden)

    Selma Forni

    2006-08-01

    Full Text Available Dados de um rebanho comercial da raça Nelore foram analisados com os objetivos de avaliar a influência de fatores ambientais e estimar parâmetros genéticos para a característica dias para o parto (DPP. Foram utilizados modelos fixos que incluíram os efeitos de grupo de contemporâneos, sexo do bezerro, idade da vaca no início da estação de monta, mês do parto anterior e peso do bezerro desmamado no final da estação de monta (apenas este último efeito não influenciou a característica significativamente. Duas definições de grupo de contemporâneos foram consideradas: a primeira definida pelas informações fazenda, ano e estação de monta, grupos de manejo (nascimento, desmama e reprodução e tipo de serviço (monta natural, monta controlada ou inseminação artificial; e a segunda, pelas mesmas informações mais o sexo do bezerro. As análises genéticas foram realizadas com conjuntos de dados que incluíram ou não os animais sem registros de parto. Quando incluídos, o valor de DPP atribuído a esses animais foi igual ao maior valor observado dentro do grupo de manejo somado a 21 dias. Os componentes de variância foram estimados por máxima verossimilhança restrita utilizando-se modelos animal unicaracterística. A inclusão do efeito aleatório de ambiente permanente nos modelos foi avaliada mediante o "Likelihood Ratio Test". As herdabilidades estimadas variaram entre 0,01 e 0,11 e a inclusão do efeito de ambiente permanente nos modelos foi significativa, de modo que a exclusão deste efeito superestimou a variância genética aditiva. A metodologia aplicada para penalizar os animais que não pariram não melhorou a identificação das diferenças genéticas entre eles. Os resultados indicaram que, como grande parte das características reprodutivas em bovinos, a DPP sofre grande influência do ambiente.Data from a Nelore population was used to evaluate environmental effects and to estimate genetic parameters for days

  7. Laser Doppler flowmetry for bone blood flow measurement: correlation with microsphere estimates and evaluation of the effect of intracapsular pressure on femoral head blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Swiontkowski, M.F.; Tepic, S.; Perren, S.M.; Moor, R.; Ganz, R.; Rahn, B.A.

    1986-01-01

    Laser Doppler flowmetry (LDF) was used to measure bone blood flow in the rabbit femoral condyles. To correlate the LDF output signal blood cell flux to in vivo blood flow, simultaneous measurements using LDF and /sup 85/Sr-labeled microspheres were made in an adult rabbit model. There was no correlation between the two methods for blood flow in the femoral condyles and the correlation between the two methods for blood flow in the femoral head does not achieve statistical significance. An LDF signal of 0.4 V was approximately equal to a microsphere measured flow rate of 0.4 ml blood/g bone/min. The strength of the correlation in the latter case may have been affected by (a) large arteriovenous shunts, (b) inadequate mixing of the microspheres with a left ventricular injection, and (c) insufficient numbers of microspheres present in the bone samples. When LDF was used to evaluate the effect of elevated intracapsular pressure on femoral head blood flow in skeletally mature rabbits, femoral head subchondral bone blood flow declined with increasing intracapsular pressure from a baseline value of 0.343 +/- 0.036 to a value of 0.127 +/- 0.27 at 120 cm of water pressure. The decline in femoral head blood flow was statistically significant at pressures of 40 cm of water or higher (p less than 0.001), and evaluation of sections of the proximal femora made from preterminal disulphine blue injections confirmed these findings. Intracapsular tamponade has an adverse effect on femoral head blood flow beginning well below central venous pressure and should be considered in the pathophysiology of posttraumatic and nontraumatic necrosis of the femoral head. Laser Doppler flowmetry was easy to use and appears to be a reproducible technique for evaluating femoral head blood flow, offering distinct advantages over the microsphere technique for measuring bone blood flow.

  8. Monoclinic deformation of calcite crystals at ambient conditions

    Science.gov (United States)

    Przeniosło, R.; Fabrykiewicz, P.; Sosnowska, I.

    2016-09-01

    High resolution synchrotron radiation powder diffraction shows that the average crystal structure of calcite at ambient conditions is described with the trigonal space group R 3 bar c but there is a systematic hkl-dependent Bragg peak broadening. A modelling of this anisotropic peak broadening with the microstrain model from Stephens (1999) [15] is presented. The observed lattice parameters' correlations can be described by assuming a monoclinic-type deformation of calcite crystallites. A quantitative model of this monoclinic deformation observed at ambient conditions is described with the space group C 2 / c . The monoclinic unit cell suggested at ambient conditions is related with the monoclinic unit cell reported in calcite at high pressure (Merrill and Bassett (1975) [10]).

  9. PRESSURE COMPENSATION METHOD OF UNDERWATER HYDRAULIC SYSTEM WITH HYDRAULIC POWER UNIT BEING UNDER ATMOSPHERIC CIRCUMSTANCE AND PRESSURE COMPENSATED VALVE

    Institute of Scientific and Technical Information of China (English)

    Wang Qingfeng; Li Yanmin; Zhong Tianyu; Xu Guohua

    2005-01-01

    Based on the analysis of the-state-of-the-art of pressure compensation of underwater hydraulic systems (UHSs), a new method of pressure compensation of UHSs, whose hydraulic power unit is in the atmospheric circumstance, is proposed. And a pilot-operated relief valve with pressure compensation is realized. The pressure compensation precision is guaranteed by direct detection. Its dynamic performance and stability are improved by a dynamic feedback. Theoretical study, simulation and experiment show that the pilot-operated relief valve with pressure compensation has a fine property of tracking underwater ambient pressure and meet the requirement of underwater ambient pressure compensation.

  10. Ambiente juvenil: discurso ambiental entre jóvenes universitarios.

    OpenAIRE

    Quinn-Anderson, William C.

    2008-01-01

    Esta tesis pretende hacer una aportación al conocimiento del medio ambiente del occidente de México, específicamente de la zona metropolitana de Guadalajara, a partir del estudio de la cultura ambiental manifestada en el discurso de los jóvenes universitarios del ITESO. La apuesta es que puede ser provechoso considerar dentro del concepto de “medio ambiente” no solamente componentes bióticos y abióticos, sino también elementos socioculturales como cultura y significado. Es evidente que hay in...

  11. Influence of surrounding gas, composition and pressure on plasma plume dynamics of nanosecond pulsed laser-induced aluminum plasmas

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-10-01

    Full Text Available In this article, we present a comprehensive study of the plume dynamics of plasmas generated by laser ablation of an aluminum target. The effect of both ambient gas composition (helium, nitrogen or argon and pressure (from ∼5 × 10−7 Torr up to atmosphere is studied. The time- and space- resolved observation of the plasma plume are performed from spectrally integrated images using an intensified Charge Coupled Device (iCCD camera. The iCCD images show that the ambient gas does not significantly influence the plume as long as the gas pressure is lower than 20 Torr and the time delay below 300 ns. However, for pressures higher than 20 Torr, the effect of the ambient gas becomes important, the shortest plasma plume length being observed when the gas mass species is highest. On the other hand, space- and time- resolved emission spectroscopy of aluminum ions at λ = 281.6 nm are used to determine the Time-Of-Flight (TOF profiles. The effect of the ambient gas on the TOF profiles and therefore on the propagation velocity of Al ions is discussed. A correlation between the plasma plume expansion velocity deduced from the iCCD images and that estimated from the TOF profiles is presented. The observed differences are attributed mainly to the different physical mechanisms governing the two diagnostic techniques.

  12. An Erosion Aggressiveness Index (EAI) Based on Pressure Load Estimation Due to Bubble Collapse in Cavitating Flows Within the RANS Solvers

    OpenAIRE

    Bergeles, G.; Koukouvinis, P.; Gavaises, M.; Li, J; Wang, L.

    2015-01-01

    Despite numerous research efforts, there is no reliable and widely accepted tool for the prediction of erosion prone material surfaces due to collapse of cavitation bubbles. In the present paper an Erosion Aggressiveness Index (EAI) is proposed, based on the pressure loads which develop on the material surface and the material yield stress. EAI depends on parameters of the liquid quality and includes the fourth power of the maximum bubble radius and the bubble size number density distribution...

  13. Conhecimento, interdisciplinaridade e Psicologia Ambiental

    Directory of Open Access Journals (Sweden)

    Ombretta Romice

    2005-01-01

    Full Text Available Responde às questões - como os métodos da Psicologia Ambiental devem ser discutidos em um enquadramento interdisciplinar; a Psicologia Ambiental pede alguma abordagem metodológica especial; como a intervenção ambiental é determinada pela interdisciplinaridade; quais são estas disciplinas e como elas se relacionam entre si - baseando-se em experiências profissionais como orientador em um projeto com comunidade, com habitação popular e exclusão social em vários países da Europa, e como consultora. Conclui que as abordagens usadas pelas diferentes profissões são muito separadas, e que apenas metas comuns não são suficientes, sendo também necessários um treino conjunto e identidade de valores.

  14. Near-ambient solid polymer fuel cell

    Science.gov (United States)

    Holleck, G. L.

    1993-01-01

    Fuel cells are extremely attractive for extraterrestrial and terrestrial applications because of their high energy conversion efficiency without noise or environmental pollution. Among the various fuel cell systems the advanced polymer electrolyte membrane fuel cells based on sulfonated fluoropolymers (e.g., Nafion) are particularly attractive because they are fairly rugged, solid state, quite conductive, of good chemical and thermal stability and show good oxygen reduction kinetics due to the low specific adsorption of the electrolyte on the platinum catalyst. The objective of this program is to develop a solid polymer fuel cell which can efficiently operate at near ambient temperatures without ancillary components for humidification and/or pressurization of the fuel or oxidant gases. During the Phase 1 effort we fabricated novel integral electrode-membrane structures where the dispersed platinum catalyst is precipitated within the Nafion ionomer. This resulted in electrode-membrane units without interfacial barriers permitting unhindered water diffusion from cathode to anode. The integral electrode-membrane structures were tested as fuel cells operating on H2 and O2 or air at 1 to 2 atm and 10 to 50 C without gas humidification. We demonstrated that cells with completely dry membranes could be self started at room temperature and subsequently operated on dry gas for extended time. Typical room temperature low pressure operation with unoptimized electrodes yielded 100 mA/cm(exp 2) at 0.5V and maximum currents over 300 mA/cm(exp 2) with low platinum loadings. Our results clearly demonstrate that operation of proton exchange membrane fuel cells at ambient conditions is feasible. Optimization of the electrode-membrane structure is necessary to assess the full performance potential but we expect significant gains in weight and volume power density for the system. The reduced complexity will make fuel cells also attractive for smaller and portable power supplies and as

  15. Monitoring the tidal response of a sea levee with ambient seismic noise

    Science.gov (United States)

    Planès, Thomas; Rittgers, Justin B.; Mooney, Michael A.; Kanning, Wim; Draganov, Deyan

    2017-03-01

    Internal erosion, a major cause of failure of earthen dams and levees, is often difficult to detect at early stages using traditional visual inspection. The passive seismic-interferometry technique could enable the early detection of internal changes taking place within these structures. We test this technique on a portion of the sea levee of Colijnsplaat, Netherlands, which presents signs of concentrated seepage in the form of sandboils. Applying seismic interferometry to ambient noise collected over a 12-hour period, we retrieve surface waves propagating along the levee. We identify the contribution of two dominant ambient seismic noise sources: the traffic on the Zeeland bridge and a nearby wind turbine. Here, the sea-wave action does not constitute a suitable noise source for seismic interferometry. Using the retrieved surface waves, we compute time-lapse variations of the surface-wave group velocities during the 12-hour tidal cycle for different frequency bands, i.e., for different depth ranges. The estimated group-velocity variations correlate with variations in on-site pore-water pressure measurements that respond to tidal loading. We present lateral profiles of these group-velocity variations along a 180-meter section of the levee, at four different depth ranges (0m-40m). On these profiles, we observe some spatially localized relative group-velocity variations of up to 5% that might be related to concentrated seepage.

  16. Validating Firewalls in Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Hansen, René Rydhof

    1999-01-01

    The ambient calculus is a calculus of computation that allows active processes (mobile ambients) to move between sites. A firewall is said to be protective whenever it denies entry to attackers not possessing the required passwords. We devise a polynomial time algorithm for rejecting proposed...... firewalls that are not guaranteed to be protective. This is based on a control flow analysis for recording what processes may turn up inside what other processes; in particular, we develop a syntax-directed system for specifying the acceptability of an analysis, we prove that all acceptable analyses...

  17. Ambient cosmology and spacetime singularities

    CERN Document Server

    Antoniadis, Ignatios

    2015-01-01

    We present a new approach to the issues of spacetime singularities and cosmic censorship in general relativity. This is based on the idea that standard 4-dimensional spacetime is the conformal infinity of an ambient metric for the 5-dimensional Einstein equations with fluid sources. We then find that the existence of spacetime singularities in four dimensions is constrained by asymptotic properties of the ambient 5-metric, while the non-degeneracy of the latter crucially depends on cosmic censorship holding on the boundary.

  18. Ambient cosmology and spacetime singularities

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, Ignatios [Bern University, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland); Ecole Polytechnique, Palaiseau (France); Cotsakis, Spiros [CERN, Theory Division, Department of Physics, Geneva 23 (Switzerland); National Technical University, School of Applied Mathematics and Physical Sciences, Athens (Greece)

    2015-01-01

    We present a new approach to the issues of spacetime singularities and cosmic censorship in general relativity. This is based on the idea that standard 4-dimensional spacetime is the conformal infinity of an ambient metric for the 5-dimensional Einstein equations with fluid sources. We then find that the existence of spacetime singularities in four dimensions is constrained by asymptotic properties of the ambient 5-metric, while the non-degeneracy of the latter crucially depends on cosmic censorship holding on the boundary. (orig.)

  19. Medio ambiente y responsabilidad social

    OpenAIRE

    2012-01-01

    Las organizaciones, dentro de los procesos de responsabilidad social y con el fin de mejorar la calidad de vida de las comunidades que impactan, han optado por proteger y preservar el medio ambiente de acuerdo a ciertos protocolos y normas internacionales que generan una cultura al respecto. Este cuaderno de investigación aborda la norma ISO 26000, la cual asume el tema de la Responsabilidad Social Empresarial (RSE) en materia de medio ambiente y es una guía para ser implementada en las orga...

  20. Los estudios sobre el ambiente y la ciencia ambiental

    Directory of Open Access Journals (Sweden)

    Amelia Nancy Giannuzzo

    2010-03-01

    Full Text Available La existencia de la ciencia ambiental es reconocida en libros, revistas de publicación científica y carreras de grado y posgrado. Sin embargo, se desconoce su existencia en forma literal o indirecta, al no ser considerado su aporte, por ejemplo, en los planteos referidos sobre la ciencia y la tecnología de la sustentabilidad. En este trabajo se presentan estos antecedentes, relacionándolos con el objetivo del mismo, que es el de aportar a la dilucidación de la existencia y conformación de la ciencia ambiental. Para esto, se analiza la relación de las disciplinas con la dimensión compleja del ambiente como objeto de estudio y aspectos metodológicos derivados. A los fines de aportar al esclarecimiento conceptual, se identifican las distintas acepciones de ambiente comúnmente referidas en la bibliografía. Además, se discuten aspectos relacionados de multidisciplinariedad, interdisciplinariedad y transdisciplinariedad, y sobre el status epistémico de la ciencia ambiental. Se concluye que una mayor precisión conceptual embasada en un marco compartido por las disciplinas que estudian el ambiente, incluida la ciencia ambiental, y los distintos actores involucrados en las problemáticas ambientales, favorecerá el refinamiento de las metodologías tendientes a disminuir la fragmentación de las investigaciones concernientes y las aplicaciones para su resolución.The existence of an environmental science is recognized in books, journals of science as well as in undergraduate and graduate studies. Its existence, however, is unknown either literally or indirectly when, for instance, its contribution to topics connected to the science and technology of sustainability is not considered. This background is presented in this paper and connected to its objective, which is to elucidate the existence and structure of the environmental science. To this goal, I analyse the relationship of the disciplines with the complex dimension of the environment

  1. Pressure-induced superconductivity in Bi single crystals

    Science.gov (United States)

    Li, Yufeng; Wang, Enyu; Zhu, Xiyu; Wen, Hai-Hu

    2017-01-01

    Measurements on resistivity and magnetic susceptibility have been carried out for Bi single crystals under pressures up to 10.5 GPa. The temperature dependent resistivity shows a semimetallic behavior at ambient and low pressures (below about 1.6 GPa). This is followed by an upturn of resistivity in the low temperature region when the pressure is increased, which is explained as a semiconductor behavior. This feature gradually gets enhanced up to a pressure of about 2.52 GPa. Then a nonmonotonic temperature dependent resistivity appears upon further increasing pressure, which is accompanied by a strong suppression to the low temperature resistivity upturn. Simultaneously, a superconducting transition occurs at about 3.92 K under a pressure of about 2.63 GPa. With further increasing pressure, a second superconducting transition emerges at about 7 K under about 2.8 GPa. For these two superconducting states, the superconductivity induced magnetic screening volumes are quite large. As the pressure further increases to 8.1 GPa, we observe the third superconducting transition at about 8.2 K. The resistivity measurements under magnetic field allow us to determine the upper critical fields μ0Hc 2 of the superconducting phases. The upper critical field for the phase with Tc=3.92 K is extremely low. Based on the Werthamer-Helfand-Hohenberg (WHH) theory, the estimated value of μ0Hc 2 for this phase is about 0.103 T, while the upper critical field for the phase with Tc=7 K is very high with a value of about 4.56 T. Finally, we present a pressure dependent phase diagram of Bi single crystals. Our results reveal the interesting and rich physics in bismuth single crystals under high pressure.

  2. Estimation of surface desorption times in hydrophobically coated nanochannels and their effect on shear-driven and pressure-driven chromatography

    NARCIS (Netherlands)

    Detobel, Frederik; Fekete, Veronika; De Malsche, Wim; De Bruyne, Selm; Gardeniers, Han; Desmet, Gert

    2009-01-01

    The present paper provides a detailed analysis of the analyte-wall adsorption effects in nanochannels, including a random walk study of the analyte-wall collision frequency, and uses these insights to estimate wall desorption times from chromatographic experiments in nanochannels. Using coumarin dye

  3. Compliant Foil Journal Bearing Performance at Alternate Pressures and Temperatures

    Science.gov (United States)

    Bruckner, Robert J.; Puleo, Bernadette J.

    2008-01-01

    An experimental test program has been conducted to determine the highly loaded performance of current generation gas foil bearings at alternate pressures and temperatures. Typically foil bearing performance has been reported at temperatures relevant to turbomachinery applications but only at an ambient pressure of one atmosphere. This dearth of data at alternate pressures has motivated the current test program. Two facilities were used in the test program, the ambient pressure rig and the high pressure rig. The test program utilized a 35 mm diameter by 27 mm long foil journal bearing having an uncoated Inconel X-750 top foil running against a shaft with a PS304 coated journal. Load capacity tests were conducted at 3, 6, 9, 12, 15, 18, and 21 krpm at temperatures from 25 to 500 C and at pressures from 0.1 to 2.5 atmospheres. Results show an increase in load capacity with increased ambient pressure and a reduction in load capacity with increased ambient temperature. Below one-half atmosphere of ambient pressure a dramatic loss of load capacity is experienced. Additional lightly loaded foil bearing performance in nitrogen at 25 C and up to 48 atmospheres of ambient pressure has also been reported. In the lightly loaded region of operation the power loss increases for increasing pressure at a fixed load. Knowledge of foil bearing performance at operating conditions found within potential machine applications will reduce program development risk of future foil bearing supported turbomachines.

  4. Environmental health indicators Indicadores de salud ambiental

    Directory of Open Access Journals (Sweden)

    Manuel Posada de la Paz

    2004-12-01

    Full Text Available This presentation gives a general overview of the project titled Environmental Health Indicators, coordinated by WHO and managed by the Research Centre on the Toxic Oil Syndrome and Rare Diseases in Spain. The presentations describes the objectives of the project, the steps taken and the results obtained during the feasibility study. The project aims to develop an environmental health information system that will allow the monitoring of public health and its health determinants and make international comparisons, develop environmental policies and facilitate communication with citizens. WHO developed a methodology for the development of these indicators within the conceptual framework of DPSEEA (Driving Force, Pressure, State, Exposure, Effect, Action and selected a total of 55 indicators (which included 168 variables in 10 environmental health areas. The feasibility study predicted the successful gathering of 89% of the indicators. However, data recollection proved difficult due to the frequent incompatibility of some variables in the Spanish information systems with the WHO defined variables. On a management level, the greatest difficulty arose from the disperse distribution of responsibilities in environmental health matters. In addition to the technical contribution of this project to Environmental Health in Spain, an added value has been to establish a close collaboration with the different Ministries involved.Esta ponencia presenta una visión general del proyecto de Indicadores de Salud Ambiental, coordinado por la OMS a nivel internacional y liderado por el Centro de Investigación sobre el Síndrome del Aceite Tóxico y Enfermedades Raras (CISATER en España. En ella se describen los objetivos del proyecto, las gestiones realizadas y los resultados obtenidos durante la fase de viabilidad de este proyecto. El proyecto consiste en el establecimiento de un sistema de información sobre salud ambiental que permita desarrollar una vigilancia

  5. Setting thresholds to varying blood pressure monitoring intervals differentially affects risk estimates associated with white-coat and masked hypertension in the population.

    Science.gov (United States)

    Asayama, Kei; Thijs, Lutgarde; Li, Yan; Gu, Yu-Mei; Hara, Azusa; Liu, Yan-Ping; Zhang, Zhenyu; Wei, Fang-Fei; Lujambio, Inés; Mena, Luis J; Boggia, José; Hansen, Tine W; Björklund-Bodegård, Kristina; Nomura, Kyoko; Ohkubo, Takayoshi; Jeppesen, Jørgen; Torp-Pedersen, Christian; Dolan, Eamon; Stolarz-Skrzypek, Katarzyna; Malyutina, Sofia; Casiglia, Edoardo; Nikitin, Yuri; Lind, Lars; Luzardo, Leonella; Kawecka-Jaszcz, Kalina; Sandoya, Edgardo; Filipovský, Jan; Maestre, Gladys E; Wang, Jiguang; Imai, Yutaka; Franklin, Stanley S; O'Brien, Eoin; Staessen, Jan A

    2014-11-01

    Outcome-driven recommendations about time intervals during which ambulatory blood pressure should be measured to diagnose white-coat or masked hypertension are lacking. We cross-classified 8237 untreated participants (mean age, 50.7 years; 48.4% women) enrolled in 12 population studies, using ≥140/≥90, ≥130/≥80, ≥135/≥85, and ≥120/≥70 mm Hg as hypertension thresholds for conventional, 24-hour, daytime, and nighttime blood pressure. White-coat hypertension was hypertension on conventional measurement with ambulatory normotension, the opposite condition being masked hypertension. Intervals used for classification of participants were daytime, nighttime, and 24 hours, first considered separately, and next combined as 24 hours plus daytime or plus nighttime, or plus both. Depending on time intervals chosen, white-coat and masked hypertension frequencies ranged from 6.3% to 12.5% and from 9.7% to 19.6%, respectively. During 91 046 person-years, 729 participants experienced a cardiovascular event. In multivariable analyses with normotension during all intervals of the day as reference, hazard ratios associated with white-coat hypertension progressively weakened considering daytime only (1.38; P=0.033), nighttime only (1.43; P=0.0074), 24 hours only (1.21; P=0.20), 24 hours plus daytime (1.24; P=0.18), 24 hours plus nighttime (1.15; P=0.39), and 24 hours plus daytime and nighttime (1.16; P=0.41). The hazard ratios comparing masked hypertension with normotension were all significant (Phypertension requires setting thresholds simultaneously to 24 hours, daytime, and nighttime blood pressure. Although any time interval suffices to diagnose masked hypertension, as proposed in current guidelines, full 24-hour recordings remain standard in clinical practice.

  6. Ultrasonic measurements of single-crystal gold under hydrostatic pressures up to 8 GPa in a Kawai-type multi-anvil apparatus

    Institute of Scientific and Technical Information of China (English)

    SONG MaoShuang; Akira YONEDA; Eiji ITO

    2007-01-01

    Ultrasonic measurements were conducted on single-crystal gold at ambient condition and hydrostatic pressures up to 8 GPa at room temperature in a Kawai-type multi-anvil apparatus.The P-wave velocities measured at high pressures were in good agreement with Daniels and Smith's ultrasonic tudy.The three independent elastic constants of gold at ambient condition were determined to be C11=192.7 GPa,C12=162.9 GPa,and C44=42.4 GPa.On the basis of an analysis of previous elastic data and the present ultrasonic data,the pressure derivatives of three elastic constants were estimated to be C11=7.12,C12=6.24,and C44=1.82.The calculated values of isothermal bulk modulus(KTO)and its pressure derivatives(K'TO)are KTO=166.44 GPa and K'TO=6.56.This indicates that Anderson et al.'s model of equation of state of gold might underestimates pressure about 1 GPa at pressure around 23 GPa and ambient temperature.Our results explained the discrepancies among the models of equation f state of gold proposed previously.

  7. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  8. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    1998-01-01

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  9. Abstract Interpretation of Mobile Ambients

    DEFF Research Database (Denmark)

    Hansen, René Rydhof; Jensen, J. G.; Nielson, Flemming

    1999-01-01

    We demonstrate that abstract interpretation is useful for analysing calculi of computation such as the ambient calculus (which is based on the p-calculus); more importantly, we show that the entire development can be expressed in a constraint-based formalism that is becoming exceedingly popular...

  10. Nanomaterials vs Ambient Ultrafine Particles

    DEFF Research Database (Denmark)

    Stone, Vicki; Miller, Mark R.; Clift, Martin J. D.

    2016-01-01

    BACKGROUND: A rich literature exists that has demonstrated adverse human health effects following exposure to ambient air particulate matter (PM), with strong support for an important role for ultrafine (nano-sized) particles. At present, relatively little human health or epidemiology data exists...

  11. Shape analysis for mobile ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2001-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safely and accurately predicts which processes may turn up at what sites during the execution of a composite system...

  12. Shape analysis for Mobile Ambients

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2000-01-01

    The ambient calculus is a calculus of computation that allows active processes to move between sites. We present an analysis inspired by state-of-the-art pointer analyses that safety and accurately predicts which processes may turn up at what sites during the execution of a composite system...

  13. Digital identity in ambient environments

    NARCIS (Netherlands)

    Schouten, Ben; Ambekar, Onkar

    2006-01-01

    Embedded systems and ambient technology enable users to interact at any time and anywhere. In the BASIS project for identity management, CWI investigates transparent biometrics in home environments. Possible application areas are user profiling for shopping , listening to one's favourite music and o

  14. La crisis del medio ambiente

    Directory of Open Access Journals (Sweden)

    Juan Carlos Quintero Vélez

    2013-07-01

    Full Text Available Este artículo, introducción al tema del medio ambiente, pretende proporcionar conceptos básicos para analizar y dimensionar el impacto que genera el hombre sobre los sistemas que soportan la vida. Para entender estos problemas, es indispensable partir de un análisis básico de la relación entre el hombre actual, su medio ambiente, sus necesidades y sus actividades. El autor revisa los antecedentes, las causas y las consecuencias de la crisis ambiental internacional, e intenta dar explicación a la problemática nacionalen este campo, y establecer los puntos más críticos en Colombia. Finalmente, con base en los parámetros establecidos por el gobierno, se presenta el concepto de“desarrollo sostenible" como modelo que interrelaciona los procesos económicos, sociales y tecnológicos con el medio ambiente.

  15. Fluid pressure arrival time tomography: Estimation and assessment in the presence of inequality constraints, with an application to a producing gas field at Krechba, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Rucci, A.; Vasco, D.W.; Novali, F.

    2010-04-01

    Deformation in the overburden proves useful in deducing spatial and temporal changes in the volume of a producing reservoir. Based upon these changes we estimate diffusive travel times associated with the transient flow due to production, and then, as the solution of a linear inverse problem, the effective permeability of the reservoir. An advantage an approach based upon travel times, as opposed to one based upon the amplitude of surface deformation, is that it is much less sensitive to the exact geomechanical properties of the reservoir and overburden. Inequalities constrain the inversion, under the assumption that the fluid production only results in pore volume decreases within the reservoir. We apply the formulation to satellite-based estimates of deformation in the material overlying a thin gas production zone at the Krechba field in Algeria. The peak displacement after three years of gas production is approximately 0.5 cm, overlying the eastern margin of the anticlinal structure defining the gas field. Using data from 15 irregularly-spaced images of range change, we calculate the diffusive travel times associated with the startup of a gas production well. The inequality constraints are incorporated into the estimates of model parameter resolution and covariance, improving the resolution by roughly 30 to 40%.

  16. Effects of ambient conditions on multi-capillary ventilation rate

    Directory of Open Access Journals (Sweden)

    Zhang Qing

    2016-01-01

    Full Text Available As a major physical parameter for the tobacco industry, the ventilation rate of cigarette should be measured reliably. Theoretical and numerical investigation on ef-fects of ambient conditions (e. g., cumulative flux of ozone and additional pressure drop on the ventilation rate was carried out. It was found that the standards exhibited a non-linear airflow component, which explains why additional pressure drop has an effect on the calibrated value, and had low sensitivity to cumulative flux of ozone.

  17. Bayesian Ambient Noise Inversion for Geoacoustic Uncertainty Estimation

    Science.gov (United States)

    2013-09-30

    methods such as the iterative Papoulis -Gerchberg algorithm16 or its non-iterative versions17 can be used for extrapolation. Figure 2(a) shows an example...difference between the extrapolated and the true coherence is due to the slow convergence of the Papoulis - Gerchberg algorithm,16 which in Figure 2(b) was...extrapolation do not agree with the results from a true 12-m aperture. The extrapolation technique using the Papoulis - Gerchberg algorithm is also

  18. Mineral Chemistry and Pressure and Temperature Estimates of Metasedimentary Rocks of the Araxá Group in the Region of Morrinhos, South of Goiás State

    Directory of Open Access Journals (Sweden)

    Guillermo Rafael Beltran Navarro

    2011-08-01

    Full Text Available In the Morrinhos region, Goiás state, Brazil, the rocks of the Araxá Group have mineral assemblages related to themetamorphic peak which occurred in this region and is typical of the amphibolite facies (kyanite zone. These rocks areassociated with the initial stage of the main ductile deformation that occurred in this area. Thermobarometric calculations,including the associations, garnet + plagioclase + biotite + muscovite; garnet + plagioclase +biotite + muscovite + kyanite;garnet + plagioclase + biotite + muscovite + amphibole, with quartz in excess, indicate that the metamorphic peak occurredat temperatures of approximately 610ºC and pressures in the order of 10 kbar. The P-T path is probably clockwise and is inagreement with the tectonic conditions observed in collisional settings.

  19. Estimation of the fluid excess pressure of hydraulic fractures in paleo geothermal reservoirs; Abschaetzung des Fluidueberdrucks von hydraulischen Bruechen in palaeogeothermischen Reservoiren

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, Sonja L. [Goettingen Univ. (Germany). Geowissenschaftliches Zentrum

    2011-10-24

    In many geothermal reservoirs to low natural permeabilities have to be enhanced by opening or shearing the existing fractures or by generating artificial hydraulic fractures (reservoir stimulation). Such hydraulic fractures can also occur naturally and will remain in paleo geothermal reservoirs. Using the example of calcite passages in a Jurassic limestone-marl alternations in southwest England the author of the contribution under consideration shows that the fault zones (mainly normal faults) were used as fluid transport pathways for calcium carbonate containing water which was injected as hydraulic fractures in the host rock. Overall, in consensus with isotopic studies it was shown that geothermal waters with relatively local origin were within the sedimentary basin and did not come from great depths. The pore fluid pressure within the limestone beds is not sufficient as a reason for the formation of calcite passages.

  20. A comparison of the indirect estimate of mean arterial pressure calculated by the conventional equation and calculated to compensate for a change in heart rate.

    Science.gov (United States)

    Rogers, G; Oosthuyse, T

    2000-02-01

    The standard equation used to calculate mean arterial pressure (MAP) assumes that diastole persists for 2/3 and systole for 1/3 of each cardiac cycle. This ratio is altered when heart rate increases, and therefore we investigated the efficacy of predicting MAP during exercise using non-invasive indirect methods. Eight subjects exercised on a cycle ergometer for 3 minute intervals to elicit heart rates between 100-110, 120-130, 140-150, 160-170, and 180-190 beats/min. In the last minute of each 3 min interval an ECG recording was taken and systolic (SP) and diastolic (DP) blood pressure was measured by manual auscultation. MAP was calculated for each heart rate interval by: MAP=DP+1/3(SP-DP) (method A), and MAP= DP + Fs(SP- DP) (method B), where Fs is the fraction of the cardiac cycle comprising systole, measured from the ECG. Fs increased from 0.35+/-0.049 at rest to 0.47+/-0.039 at a heart rate of 180-190 beats/min. MAP measured by method B was consistently greater than MAP calculated by method A at all heart rates greater than resting heart rate (pequation (method A) to derive MAP during exercise (measured as the percentage difference between method A and B) increased linearly with heart rate (r=0.98). The standard MAP equation should not be applied during exercise, as it does not account for the change in the systolic: diastolic period ratio as heart rate increases.