WorldWideScience

Sample records for surface pressure field

  1. Indirect measurement of near-surface velocity and pressure fields based on measurement of moving free surface profiles

    International Nuclear Information System (INIS)

    Sibamoto, Yasuteru; Nakamura, Hideo

    2005-01-01

    A non-intrusive technique for measurement of the velocity and pressure fields adjacent to a moving fluid surface is developed. The technique is based on the measurement of fluid surface profile. The velocity and pressure fields are derived with use of the boundary element method (BEM) by seeking for an incompressible flow field that satisfies the kinematic boundary condition imposed by the time-dependent fluid surface profile. The proposed technique is tested by deriving the velocity and pressure fields inversely from the fluid surface profiles obtained by a forward BEM calculation of fluid surface response to externally-imposed pressure. The inverse calculation results show good agreement with the imposed pressure distribution in the forward calculation. (author)

  2. Surface pressure fluctuations on aircraft flaps and their correlation with far-field noise

    Science.gov (United States)

    Guo, Y. P.; Joshi, M. C.; Bent, P. H.; Yamamoto, K. J.

    2000-07-01

    This paper discusses unsteady surface pressures on aircraft flaps and their correlation with far-field noise. Analyses are made of data from a 4.7% DC-10 aircraft model test, conducted in the 40 × 80 feet wind tunnel at NASA Ames Research Center. Results for various slat/wing/flap configurations and various flow conditions are discussed in detail to reveal major trends in surface pressure fluctuations. Spectral analysis, including cross-correlation/coherence, both among unsteady surface pressures and between far-field noise and near-field fluctuations, is used to reveal the most coherent motions in the near field and identify potential sources of noise related to flap flows. Dependencies of surface pressure fluctuations on mean flow Mach numbers, flap settings and slat angles are discussed. Dominant flow features in flap side edge regions, such as the formation of double-vortex structures, are shown to manifest themselves in the unsteady surface pressures as a series of spectral humps. The spectral humps are shown to correlate well with the radiated noise, indicating the existence of major noise sources in flap side edge regions. Strouhal number scaling is used to collapse the data with satisfactory results. The effects of flap side edge fences on surface pressures are also discussed. It is shown that the application of fences effectively increases the thickness of the flaps so that the double-vortex structures have more time to evolve. As a result, the characteristic timescale of the unsteady sources increases, which in turn leads to a decrease in the dominant frequency of the source process. Based on this, an explanation is proposed for the noise reduction mechanism of flap side edge fences.

  3. Spreading and atomization of droplets on a vibrating surface in a standing pressure field

    Science.gov (United States)

    Deepu, P.; Basu, Saptarshi; Saha, Abhishek; Kumar, Ranganathan

    2012-10-01

    We report the first observation and analytical model of deformation and spreading of droplets on a vibrating surface under the influence of an ultrasonic standing pressure field. The standing wave allows the droplet to spread, and the spreading rate varies inversely with viscosity. In low viscosity droplets, the synergistic effect of radial acoustic force and the transducer surface acceleration also leads to capillary waves. These unstable capillary modes grow to cause ultimate disintegration into daughter droplets. We find that using nanosuspensions, spreading and disintegration can be prevented by suppressing the development of capillary modes and subsequent break-up.

  4. Shock tunnel measurements of surface pressures in shock induced separated flow field using MEMS sensor array

    International Nuclear Information System (INIS)

    Sriram, R; Jagadeesh, G; Ram, S N; Hegde, G M; Nayak, M M

    2015-01-01

    Characterized not just by high Mach numbers, but also high flow total enthalpies—often accompanied by dissociation and ionization of flowing gas itself—the experimental simulation of hypersonic flows requires impulse facilities like shock tunnels. However, shock tunnel simulation imposes challenges and restrictions on the flow diagnostics, not just because of the possible extreme flow conditions, but also the short run times—typically around 1 ms. The development, calibration and application of fast response MEMS sensors for surface pressure measurements in IISc hypersonic shock tunnel HST-2, with a typical test time of 600 μs, for the complex flow field of strong (impinging) shock boundary layer interaction with separation close to the leading edge, is delineated in this paper. For Mach numbers 5.96 (total enthalpy 1.3 MJ kg −1 ) and 8.67 (total enthalpy 1.6 MJ kg −1 ), surface pressures ranging from around 200 Pa to 50 000 Pa, in various regions of the flow field, are measured using the MEMS sensors. The measurements are found to compare well with the measurements using commercial sensors. It was possible to resolve important regions of the flow field involving significant spatial gradients of pressure, with a resolution of 5 data points within 12 mm in each MEMS array, which cannot be achieved with the other commercial sensors. In particular, MEMS sensors enabled the measurement of separation pressure (at Mach 8.67) near the leading edge and the sharply varying pressure in the reattachment zone. (paper)

  5. Seasonal Variations of the Earth's Gravitational Field: An Analysis of Atmospheric Pressure, Ocean Tidal, and Surface Water Excitation

    Science.gov (United States)

    Dong, D,; Gross, R.S.; Dickey, J.

    1996-01-01

    Monthly mean gravitational field parameters (denoted here as C(sub even)) that represent linear combinations of the primarily even degree zonal spherical harmonic coefficients of the Earth's gravitational field have been recovered using LAGEOS I data and are compared with those derived from gridded global surface pressure data of the National meteorological center (NMC) spanning 1983-1992. The effect of equilibrium ocean tides and surface water variations are also considered. Atmospheric pressure and surface water fluctuations are shown to be the dominant cause of observed annual C(sub even) variations. Closure with observations is seen at the 1sigma level when atmospheric pressure, ocean tide and surface water effects are include. Equilibrium ocean tides are shown to be the main source of excitation at the semiannual period with closure at the 1sigma level seen when both atmospheric pressure and ocean tide effects are included. The inverted barometer (IB) case is shown to give the best agreement with the observation series. The potential of the observed C(sub even) variations for monitoring mass variations in the polar regions of the Earth and the effect of the land-ocean mask in the IB calculation are discussed.

  6. Field-emitting Townsend regime of surface dielectric barrier discharges generated in CO2 emerging at high pressure

    Science.gov (United States)

    Pai, David; Stauss, Sven; Terashima, Kazuo

    2015-09-01

    Surface dielectric barrier discharges (DBDs) in CO2 from atmospheric pressure up to supercritical conditions (Tc = 304.13 K, pc = 7.4 MPa) generated using 10-kHz ac excitation are studied experimentally. Two discharge regimes are obtained: the standard and field-emitting Townsend regimes. The former resembles typical surface DBDs that have streamer-like characteristics, but the latter has not been reported previously. Here we present an analysis of the electrical and optical diagnostics of the field-emitting Townsend discharge regime using current-voltage and charge-voltage measurements, imaging, optical emission spectroscopy, and spontaneous Raman spectroscopy. Using an electrical model, it is possible to calculate the discharge-induced capacitances of the plasma and the dielectric, as well as the space-averaged values of the surface potential and the potential drop across the discharge. The model also accounts for the space-averaged Laplacian field by including the capacitance due to the fringe electric field from the electrode edge. The electrical characteristics are similar to those of atmospheric-pressure Townsend DBDs, i.e. self-sustained DBDs with minimal space-charge effects. The purely continuum emission spectrum is due to electron-neutral bremsstrahlung, with a corresponding average electron temperature of 2600 K. Raman spectra of CO2 near the critical point demonstrate that the discharge increases the average gas temperature by less than 1 K. This work was supported financially in part by MEXT and JSPS.

  7. Three-term Asymptotic Stress Field Expansion for Analysis of Surface Cracked Elbows in Nuclear Pressure Vessels

    Science.gov (United States)

    Labbe, Fernando

    2007-04-01

    Elbows with a shallow surface cracks in nuclear pressure pipes have been recognized as a major origin of potential catastrophic failures. Crack assessment is normally performed by using the J-integral approach. Although this one-parameter-based approach is useful to predict the ductile crack onset, it depends strongly on specimen geometry or constraint level. When a shallow crack exists (depth crack-to-thickness wall ratio less than 0.2) and/or a fully plastic condition develops around the crack, the J-integral alone does not describe completely the crack-tip stress field. In this paper, we report on the use of a three-term asymptotic expansion, referred to as the J- A 2 methodology, for modeling the elastic-plastic stress field around a three-dimensional shallow surface crack in an elbow subjected to internal pressure and out-of-plane bending. The material, an A 516 Gr. 70 steel, used in the nuclear industry, was modeled with a Ramberg-Osgood power law and flow theory of plasticity. A finite deformation theory was included to account for the highly nonlinear behavior around the crack tip. Numerical finite element results were used to calculate a second fracture parameter A 2 for the J- A 2 methodology. We found that the used three-term asymptotic expansion accurately describes the stress field around the considered three-dimensional shallow surface crack.

  8. Surface wind, pressure and temperature fields near tornadic and non-tornadic narrow cold-frontal rainbands

    Science.gov (United States)

    Clark, Matthew; Parker, Douglas

    2014-05-01

    Narrow cold frontal rainbands (NCFRs) occur frequently in the UK and other parts of northwest Europe. At the surface, the passage of an NCFR is often marked by a sharp wind veer, abrupt pressure increase and a rapid temperature decrease. Tornadoes and other instances of localised wind damage sometimes occur in association with meso-gamma-scale vortices (sometimes called misocyclones) that form along the zone of abrupt horizontal wind veer (and associated vertical vorticity) at the leading edge of the NCFR. Using one-minute-resolution data from a mesoscale network of automatic weather stations, surface pressure, wind and temperature fields in the vicinity of 12 NCFRs (five of which were tornadic) have been investigated. High-resolution surface analyses were obtained by mapping temporal variations in the observed parameters to equivalent spatial variations, using a system velocity determined by analysis of the radar-observed movement of NCFR precipitation segments. Substantial differences were found in the structure of surface wind and pressure fields close to tornadic and non-tornadic NCFRs. Tornadic NCFRs exhibited a large wind veer (near 90°) and strong pre- and post-frontal winds. These attributes were associated with large vertical vorticity and horizontal convergence across the front. Tornadoes typically occurred where vertical vorticity and horizontal convergence were increasing. Here, we present surface analyses from selected cases, and draw comparisons between the tornadic and non-tornadic NCFRs. Some Doppler radar observations will be presented, illustrating the development of misocyclones along parts of the NCFR that exhibit strong, and increasing, vertical vorticity stretching. The influence of the stability of the pre-frontal air on the likelihood of tornadoes will also be discussed.

  9. Hamilton-Jacobi theory for continuation of magnetic field across a toroidal surface supporting a plasma pressure discontinuity

    International Nuclear Information System (INIS)

    McGann, M.; Hudson, S.R.; Dewar, R.L.; Nessi, G. von

    2010-01-01

    The vanishing of the divergence of the total stress tensor (magnetic plus kinetic) in a neighborhood of an equilibrium plasma containing a toroidal surface of discontinuity gives boundary and jump conditions that strongly constrain allowable continuations of the magnetic field across the surface. The boundary conditions allow the magnetic fields on either side of the discontinuity surface to be described by surface magnetic potentials, reducing the continuation problem to that of solving a Hamilton-Jacobi equation. The characteristics of this equation obey Hamiltonian equations of motion, and a necessary condition for the existence of a continued field across a general toroidal surface is that there exist invariant tori in the phase space of this Hamiltonian system. It is argued from the Birkhoff theorem that existence of such an invariant torus is also, in general, sufficient for continuation to be possible. An important corollary is that the rotational transform of the continued field on a surface of discontinuity must, generically, be irrational.

  10. Investigation of the flow field around a propeller-rudder configuration: on-surface pressure measurements and velocity-pressure-phase-locked correlations

    OpenAIRE

    Felli, Mario; Falchi, Massimo; Pereira, Francisco

    2011-01-01

    The present paper deals with the problem of the propeller induced perturbation on the rudder . The study aims at providing insights on the key mechanisms governing the complex interaction between the propeller wake structures and the rudder. In this regard, a wide experimental activity that concerned PIV and LDV velocity measurements and wall-pressure-measurements on the two faces of the rudder was performed in a cavitation tunnel. The major flow features that distinguish the flow field aroun...

  11. Markov Random Field Surface Reconstruction

    DEFF Research Database (Denmark)

    Paulsen, Rasmus Reinhold; Bærentzen, Jakob Andreas; Larsen, Rasmus

    2010-01-01

    A method for implicit surface reconstruction is proposed. The novelty in this paper is the adaption of Markov Random Field regularization of a distance field. The Markov Random Field formulation allows us to integrate both knowledge about the type of surface we wish to reconstruct (the prior) and...

  12. Pressure relieving support surfaces (PRESSURE) trial: cost effectiveness analysis.

    Science.gov (United States)

    Iglesias, Cynthia; Nixon, Jane; Cranny, Gillian; Nelson, E Andrea; Hawkins, Kim; Phillips, Angela; Torgerson, David; Mason, Su; Cullum, Nicky

    2006-06-17

    To assess the cost effectiveness of alternating pressure mattresses compared with alternating pressure overlays for the prevention of pressure ulcers in patients admitted to hospital. Cost effectiveness analysis carried out alongside the pressure relieving support surfaces (PRESSURE) trial; a multicentre UK based pragmatic randomised controlled trial. 11 hospitals in six UK NHS trusts. Intention to treat population comprising 1971 participants. Kaplan Meier estimates of restricted mean time to development of pressure ulcers and total costs for treatment in hospital. Alternating pressure mattresses were associated with lower overall costs (283.6 pounds sterling per patient on average, 95% confidence interval--377.59 pounds sterling to 976.79 pounds sterling) mainly due to reduced length of stay in hospital, and greater benefits (a delay in time to ulceration of 10.64 days on average,--24.40 to 3.09). The differences in health benefits and total costs for hospital stay between alternating pressure mattresses and alternating pressure overlays were not statistically significant; however, a cost effectiveness acceptability curve indicated that on average alternating pressure mattresses compared with alternating pressure overlays were associated with an 80% probability of being cost saving. Alternating pressure mattresses for the prevention of pressure ulcers are more likely to be cost effective and are more acceptable to patients than alternating pressure overlays.

  13. Support surfaces for pressure ulcer prevention.

    Science.gov (United States)

    McInnes, Elizabeth; Jammali-Blasi, Asmara; Bell-Syer, Sally E M; Dumville, Jo C; Middleton, Victoria; Cullum, Nicky

    2015-09-03

    Pressure ulcers (i.e. bedsores, pressure sores, pressure injuries, decubitus ulcers) are areas of localised damage to the skin and underlying tissue. They are common in the elderly and immobile, and costly in financial and human terms. Pressure-relieving support surfaces (i.e. beds, mattresses, seat cushions etc) are used to help prevent ulcer development. This systematic review seeks to establish:(1) the extent to which pressure-relieving support surfaces reduce the incidence of pressure ulcers compared with standard support surfaces, and,(2) their comparative effectiveness in ulcer prevention. In April 2015, for this fourth update we searched The Cochrane Wounds Group Specialised Register (searched 15 April 2015) which includes the results of regular searches of MEDLINE, EMBASE and CINAHL and The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015, Issue 3). Randomised controlled trials (RCTs) and quasi-randomised trials, published or unpublished, that assessed the effects of any support surface for prevention of pressure ulcers, in any patient group or setting which measured pressure ulcer incidence. Trials reporting only proxy outcomes (e.g. interface pressure) were excluded. Two review authors independently selected trials. Data were extracted by one review author and checked by another. Where appropriate, estimates from similar trials were pooled for meta-analysis. For this fourth update six new trials were included, bringing the total of included trials to 59.Foam alternatives to standard hospital foam mattresses reduce the incidence of pressure ulcers in people at risk (RR 0.40 95% CI 0.21 to 0.74). The relative merits of alternating- and constant low-pressure devices are unclear. One high-quality trial suggested that alternating-pressure mattresses may be more cost effective than alternating-pressure overlays in a UK context.Pressure-relieving overlays on the operating table reduce postoperative pressure ulcer incidence

  14. Airfoil Trailing Edge Noise Generation and Its Surface Pressure Fluctuation

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong

    2015-01-01

    where the time history pressure data are recorded by the surface pressure microphones. After the flow-field is stabilized, the generated noise from the airfoil Trailing Edge (TE) is predicted using the acoustic analogy solver, where the results from LES are the input. It is found that there is a strong......In the present work, Large Eddy Simulation (LES) of turbulent flows over a NACA 0015 airfoil is performed. The purpose of such numerical study is to relate the aerodynamic surface pressure with the noise generation. The results from LES are validated against detailed surface pressure measurements...... relation between TE noise and the aerodynamic pressure. The results of power spectrum density show that the fluctuation of aerodynamic pressure is responsible for noise generation....

  15. Noise Evaluation Technique Based on Surface Pressure

    DEFF Research Database (Denmark)

    Fischer, Andreas

    2012-01-01

    In this chapter the relevant theory for the understanding of TE noise modeling is collected. It contains the acoustic formulations of [31] and [57]. Both give a relation for the far field sound pressure in dependence of the frequency wave number spectral density of the pressure on the airfoil...

  16. Field mapping of ballistic pressure pulse sources

    Directory of Open Access Journals (Sweden)

    Rad Abtin Jamshidi

    2015-09-01

    Full Text Available Ballistic pressure pulse sources are used since late 1990s for the extracorporeal treatment of chronic Enthesitis. Newly indications are found in trigger-point-therapy for the treatment of musculoskeletal disorders. In both applications excellent results without relevant side effects were found in clinical trials. The technical principle of pressure pulse source is based on the same techniques used in air guns. A projectile is accelerated by pressurized air and hits the applicator with high kinetic energy. By this a compression wave travels through the material and induces a fast (4..5μs, almost singular pressure pulse of 2..10 MPa, which is followed by an equally short rarefaction phase of about the same amplitude. It is assumed that the pressure pulse accounts for the biomedical effects of the device. The slower inertial motion of the waveguide is damped by elastic stoppers, but still can be measured several micro seconds after the initial pressure pulse. In order to characterize the pressure pulse devices, field mapping is performed on several radial pressure pulse sources using the fiber optic hydrophone and a polyvinylidenfluorid (PVDF piezoelectric hydrophone. It could be shown that the current standard (IEC 61846 is not appropriate for characterization of ballistic pressure pulse sources.

  17. High-frequency pressure variations in the vicinity of a surface CO2 flux chamber

    Science.gov (United States)

    Eugene S. Takle; James R. Brandle; R. A. Schmidt; Rick Garcia; Irina V. Litvina; William J. Massman; Xinhua Zhou; Geoffrey Doyle; Charles W. Rice

    2003-01-01

    We report measurements of 2Hz pressure fluctuations at and below the soil surface in the vicinity of a surface-based CO2 flux chamber. These measurements were part of a field experiment to examine the possible role of pressure pumping due to atmospheric pressure fluctuations on measurements of surface fluxes of CO2. Under the moderate wind speeds, warm temperatures,...

  18. Banana regime pressure anisotropy in a bumpy cylinder magnetic field

    International Nuclear Information System (INIS)

    Garcia-Perciante, A.L.; Callen, J.D.; Shaing, K.C.; Hegna, C.C.

    2006-01-01

    The pressure anisotropy is calculated for a plasma in a bumpy cylindrical magnetic field in the low collisionality (banana) regime for small magnetic-field modulations (ε≡ΔB/2B parallel is then calculated and is shown to exceed the flux-surface-averaged parallel viscous force parallel > by a factor of O(1/ε). A high-frequency limit (ω>>ν) for the pressure anisotropy is also determined and the calculation is then extended to include the full frequency dependence by using an expansion in Cordey eigenfunctions

  19. Pressure, Chaotic Magnetic Fields and MHD Equilibria

    Energy Technology Data Exchange (ETDEWEB)

    S.R. Hudson & N. Nakajima

    2010-05-12

    Analyzes of plasma behavior often begin with a description of the ideal magnetohydrodynamic equilibrium, this being the simplest model capable of approximating macroscopic force balance. Ideal force balance is when the pressure gradient is supported by the Lorentz force, ∇p = j x B. We discuss the implications of allowing for a chaotic magnetic field on the solutions to this equation. We argue that the solutions are pathological and not suitable for numerical calculations. If the pressure and magnetic Field are continuous, the only non-trivial solutions have an uncountable infinity of discontinuities in the pressure gradient and current. The problems arise from the arbitrarily small length scales in the structure of the field, and the consequence of ideal force balance that the pressure is constant along the Field-lines, B • ∇p = 0. A simple method to ameliorate the singularities is to include a small but Finite perpendicular diffusion. A self-consistent set of equilibrium equations is described and some algorithmic approaches aimed at solving these equations are discussed.

  20. Pressure Sensitive Insulated Gate Field Effect Transistor

    Science.gov (United States)

    Suminto, James Tjan-Meng

    A pressure sensitive insulated gate field effect transistor has been developed. The device is an elevated gate field-effect-transistor. It consists of a p-type silicon substrate in which two n^+ region, the source and drain, are formed. The gate electrode is a metal film sandwiched in an insulated micro-diaphragm resembling a pill-box which covers the gate oxide, drain, and source. The space between the gate electrode and the oxide is vacuum or an air-gap. When pressure is applied on the diaphragm it deflects and causes a change in the gate capacitance, and thus modulates the conductance of the channel between source and drain. A general theory dealing with the characteristic of this pressure sensitive insulated gate field effect transistor has been derived, and the device fabricated. The fabrication process utilizes the standard integrated circuit fabrication method. It features a batch fabrication of field effect devices followed by the batch fabrication of the deposited diaphragm on top of each field effect device. The keys steps of the diaphragm fabrication are the formation of spacer layer, formation of the diaphragm layer, and the subsequent removal of the spacer layer. The chip size of the device is 600 μm x 1050 mum. The diaphragm size is 200 μm x 200 mum. Characterization of the device has been performed. The current-voltage characteristics with pressure as parameters have been demonstrated and the current-pressure transfer curves obtained. They show non-linear characteristics as those of conventional capacitive pressure sensors. The linearity of threshold voltage versus pressure transfer curves has been demonstrated. The temperature effect on the device performances has been tested. The temperature coefficient of threshold voltage, rather than the electron mobility, has dominated the temperature coefficient of the device. Two temperature compensation schemes have been tested: one method is by connecting two identical PSIGFET in a differential amplifier

  1. Pressure relieving support surfaces: a randomised evaluation.

    Science.gov (United States)

    Nixon, J; Nelson, E A; Cranny, G; Iglesias, C P; Hawkins, K; Cullum, N A; Phillips, A; Spilsbury, K; Torgerson, D J; Mason, S

    2006-07-01

    To determine differences between alternating pressure overlays and alternating pressure replacement mattresses with respect to the development of new pressure ulcers, healing of existing pressure ulcers, patient acceptability and cost-effectiveness of the different pressure-relieving surfaces. Also to investigate the specific additional impact of pressure ulcers on patients' well-being. A multicentre, randomised, controlled, open, fixed sample, parallel-group trial with equal randomisation was undertaken. The trial used remote, concealed allocation and intention-to-treat (ITT) analysis. The main trial design was supplemented with a qualitative study involving a purposive sample of 20-30 patients who developed pressure ulcers, to assess the impact of the pressure ulcers on their well-being. In addition, a focus group interview was carried out with clinical research nurses, who participated in the PRESSURE (Pressure RElieving Support SUrfaces: a Randomised Evaluation) Trial, to explore the experiences of their role and observations of pressure area care. The study took place in 11 hospital-based research centres within six NHS trusts in England. Acute and elective patients aged 55 years or older and admitted to vascular, orthopaedic, medical or care of the elderly wards in the previous 24 hours were investigated. Patients were randomised to either an alternating pressure overlay or an alternating pressure mattress replacement, with mattress specifications clearly defined to enable the inclusion of centres using products from different manufacturers, and to exclude hybrid mattress systems (which either combine foam or constant low pressure with alternating pressure in one mattress, or can be used as either an overlay or a replacement mattress). Development of a new pressure ulcer (grade pressures ulcers, patient acceptability and cost-effectiveness. In total, 6155 patients were assessed for eligibility to the trial and 1972 were randomised: 990 to the alternating

  2. Sensitivity of the hand to surface pressure.

    Science.gov (United States)

    Fransson-Hall, C; Kilbom, A

    1993-06-01

    A new method of measuring pain-pressure threshold (PPT) of the hand has been developed. Externally applied surface pressure (EASP) was exerted at a certain rate of increase and the level where the feeling of pressure turned into pain was recorded. Also, the effects of sustained EASP were elucidated. Sixteen healthy right-handed subjects (eight female, eight male) participated. The distribution of the hand's sensitivity to EASP is presented. The most sensitive areas were the thenar area, the skinfold between thumb and index finger and the area around os pisiforme. When the hand was repeatedly exposed to EASP, the PPT decreased with increasing number of pressure incidents. For sustained EASP, the time of exposure was found to be important also for the quality of the sensation. Our results show that sustained EASP does not hurt at once, but becomes painful after a short time. On average, the female PPT corresponded to two-thirds of the male PPT. Females experienced pain faster than males when exposed to sustained EASP, and chose lower levels when estimating acceptable sustained EASP.

  3. Vacuum surface flashover and high pressure gas streamers

    International Nuclear Information System (INIS)

    Elizondo, J.M.; Krogh, M.L.; Smith, D.; Stolz, D.; Wright, S.N.

    1997-07-01

    Pre-breakdown current traces obtained during high pressure gas breakdown and vacuum surface flashover show similar signatures. The initial pre-breakdown current spike, a flat constant current phase, and the breakdown phase with voltage collapse and current surge differ mostly in magnitude. Given these similarities, a model, consisting of the initial current spike corresponding to a fast precursor streamer (ionization wave led by a photoionizing front), the flat current stage as the heating or glow phase, and the terminal avalanche and gap closure, is applied to vacuum surface flashover. A simple analytical approximation based on the resistivity changes induced in the vacuum and dielectric surface is presented. The approximation yields an excellent fit to pre-breakdown time delay vs applied field for previously published experimental data. A detailed kinetics model that includes surface and gas contributions is being developed based in the initial approximation

  4. Vector fields on nonorientable surfaces

    Directory of Open Access Journals (Sweden)

    Ilie Barza

    2003-01-01

    X, and the space of vector fields on X are proved by using a symmetrisation process. An example related to the normal derivative on the border of the Möbius strip supports the nontriviality of the concepts introduced in this paper.

  5. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    Science.gov (United States)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2015-07-01

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O2 = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  6. Surface states in an external electric field

    International Nuclear Information System (INIS)

    Steslicka, M.

    1975-10-01

    Under conditions typical for field ion microscopy, true surface states can exist. Their shift towards higher energies can be quite significant and, moreover, additional surface levels at still higher energies can appear. The latter can play an important role in the process of tunneling of image gas electrons into surface states

  7. Pressure ulcer prevention and pressure-relieving surfaces.

    Science.gov (United States)

    Benbow, Maureen

    Although rarely subject to media attention, political interest or research funding, pressure ulcers, and their almost inevitable increase in incidence, detrimentally affect the quality of life of thousands of patients, both in the hospital and community setting. In addition, the costs to the NHS of pressure-ulcer-related care in hospitals is estimated to be pounds sterling 1.8-pounds sterling 2.5 billion annually. Many pressure ulcers that develop could have been prevented, and there are several up-to-date, easily-accessible sources of evidence to guide decision-making regarding appropriate interventions in pressure care. Consideration and assessment of the patient holistically, followed by appropriate intervention and evaluation, is the key to any prevention strategy.

  8. Beds: practical pressure management for surfaces/mattresses.

    Science.gov (United States)

    Norton, Linda; Coutts, Patricia; Sibbald, R Gary

    2011-07-01

    The prevention and management of pressure ulcers, including support surface selection, are a primary focus of healthcare providers. This article discusses the forces contributing to pressure ulcer formation and explores choosing therapeutic support surface features based on the patient's clinical needs and on using the evidence-informed support surface algorithm and decision trees.

  9. Support surfaces for pressure ulcer prevention

    OpenAIRE

    Cullum, N; McInnes, E; Bell-Syer, SE; Legood, R

    2004-01-01

    : Pressure ulcers (also known as bedsores, pressure sores, decubitus ulcers) are areas of localised damage to the skin and underlying tissue due to pressure, shear or friction. They are common in the elderly and immobile and costly in financial and human terms. Pressure-relieving beds, mattresses and seat cushions are widely used as aids to prevention in both institutional and non-institutional settings. : This systematic review seeks to answer the following questions: to what extent do press...

  10. Support surfaces for pressure ulcer prevention

    OpenAIRE

    McInnes, E; Bell-Syer, SE; Dumville, JC; Legood, R; Cullum, NA

    2008-01-01

    Background Pressure ulcers (also known as bedsores, pressure sores, decubitus ulcers) are areas of localised damage to the skin and underlying tissue due to pressure, shear or friction. They are common in the elderly and immobile and costly in financial and human terms. Pressure-relieving beds, mattresses and seat cushions are widely used as aids to prevention in both institutional and non-institutional settings. Objectives This systematic review seeks to answer the following questions: (1) t...

  11. Interface pressure mapping pilot study to select surfaces that effectively redistribute pediatric occipital pressure.

    Science.gov (United States)

    Higer, Samantha; James, Thomas

    2016-02-01

    The aim of this pilot study was to better inform clinical decisions to prevent pediatric occipital pressure ulcers with quantitative data to choose an appropriate reactive support surface. A commercially available capacitive pressure mapping system (XSENSOR, X3 Medical Seat System, Calgary, Canada) was used to evaluate a standard pediatric mattress and four commercially available pressure-redistributing support surfaces. The pressure mapping system was validated for use in the pediatric population through studies on sensitivity, accuracy, creep, and repeatability. Then, a pilot pressure mapping study on healthy children under 6 years old (n = 22) was performed to determine interface pressure and pressure distribution between the occipital region of the skull and each surface: standard mattress, gel, foam, air and fluidized. The sensor was adequate to measure pressure generated by pediatric occipital loading, with 0.5-9% error in accuracy in the 25-95 mmHg range. The air surface had the lowest mean interface pressure (p pressure index (PPI), defined as the peak pressure averaged over four sensels, (p pressure for mattress, foam, fluidized, gel, and air materials were 24.8 ± 4.42, 24.1 ± 1.89, 19.4 ± 3.25, 17.9 ± 3.10, and 14.2 ± 1.41 mmHg, respectively. The air surface also had the most homogenous pressure distribution, with the highest mean to PPI ratio (p surfaces (p surface was the most effective pressure-redistributing material for pediatric occipital pressure as it had the lowest interface pressure and a homogeneous pressure distribution. This implies effective envelopment of the bony prominence of the occiput and increasing contact area to decrease peak pressure points. Copyright © 2015 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

  12. Electric field measurements in high pressure discharges

    International Nuclear Information System (INIS)

    Mitko, S.V.; Ochkin, V.N.; Serdyuchenko, A.Yu.; Tskhai, S.N.

    2001-01-01

    Electric fields define a wide range of interactions and phenomena at different phases of matter both on micro- and macro-level. Investigation of electric fields behavior provides a key for understanding of these phenomena and their application

  13. Modeling transducer impulse responses for predicting calibrated pressure pulses with the ultrasound simulation program Field II

    DEFF Research Database (Denmark)

    Bæk, David; Jensen, Jørgen Arendt; Willatzen, Morten

    2010-01-01

    FIELD II is a simulation software capable of predicting the field pressure in front of transducers having any complicated geometry. A calibrated prediction with this program is, however, dependent on an exact voltage-to-surface acceleration impulse response of the transducer. Such impulse response...... is not calculated by FIELD II. This work investigates the usability of combining a one-dimensional multilayer transducer modeling principle with the FIELD II software. Multilayer here refers to a transducer composed of several material layers. Measurements of pressure and current from Pz27 piezoceramic disks...... transducer model and the FIELD II software in combination give good agreement with measurements....

  14. The extended surface forces apparatus. IV. Precision static pressure control

    OpenAIRE

    Schurtenberger E; Heuberger M

    2011-01-01

    We report on design and performance of an extended surface forces apparatus (eSFA) built into a pressurized system. The aim of this instrument is to provide control over static pressure and temperature to facilitate direct surface force experiments in equilibrium with fluids at different loci of their phase diagram. We built an autoclave that can bear a miniature eSFA. To avoid mechanical or electrical feedtroughs the miniature apparatus uses an external surface coarse approach stage under am...

  15. Pressure Field Around Underwater Negative Streamers

    Czech Academy of Sciences Publication Activity Database

    Hoffer, Petr; Koláček, Karel; Lukeš, Petr; Stelmashuk, Vitaliy

    2015-01-01

    Roč. 43, č. 5 (2015), s. 1787-1792 ISSN 0093-3813 R&D Projects: GA ČR(CZ) GA15-12987S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Program:M Institutional support: RVO:61389021 Keywords : Interferometry * plasma generation * pressure measurement * water Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.958, year: 2015

  16. Field evaporation of silicon and field desorption of hydrogen from silicon surfaces

    International Nuclear Information System (INIS)

    Kellogg, G.L.

    1983-01-01

    The field evaporation of silicon in ultrahigh vacuum and in hydrogen has been studied with the use of the pulsed-laser atom probe. Measurements of the ion yields of various field-evaporated and field-desorbed species were made as a function of applied voltage, laser power, hydrogen background pressure, and laser pulse rate. The results indicate that, in ultrahigh vacuum and above cryogenic temperatures, field evaporation of silicon is qualitatively the same as for metals. In hydrogen, however, the field-evaporation process is quite different from that of metals, with the rate-limiting step being the field-enhanced formation of surface hydrides. Field-desorbed H + and H 2 + ions are shown to arise from a field-adsorbed binding state, and the voltage range where H 2 + dissociates to H + is used to calibrate the electric field strength. The low-temperature evaporation field of silicon is estimated from this calibration to be 3.3--3.6 V/A, which is considerably higher than the currently accepted value of 2.0 V/A. Field-desorbed H 3 + ions are detected only when oxide contamination is present on the silicon surface. If we assume that the mechanism of H 3 + formation is the same as that proposed for metals, this observation suggests that weakly bound, chemisorbed hydrogen atoms exist on silicon only in the presence of surface contamination

  17. Surface modifications by field induced diffusion.

    Directory of Open Access Journals (Sweden)

    Martin Olsen

    Full Text Available By applying a voltage pulse to a scanning tunneling microscope tip the surface under the tip will be modified. We have in this paper taken a closer look at the model of electric field induced surface diffusion of adatoms including the van der Waals force as a contribution in formations of a mound on a surface. The dipole moment of an adatom is the sum of the surface induced dipole moment (which is constant and the dipole moment due to electric field polarisation which depends on the strength and polarity of the electric field. The electric field is analytically modelled by a point charge over an infinite conducting flat surface. From this we calculate the force that cause adatoms to migrate. The calculated force is small for voltage used, typical 1 pN, but due to thermal vibration adatoms are hopping on the surface and even a small net force can be significant in the drift of adatoms. In this way we obtain a novel formula for a polarity dependent threshold voltage for mound formation on the surface for positive tip. Knowing the voltage of the pulse we then can calculate the radius of the formed mound. A threshold electric field for mound formation of about 2 V/nm is calculated. In addition, we found that van der Waals force is of importance for shorter distances and its contribution to the radial force on the adatoms has to be considered for distances smaller than 1.5 nm for commonly used voltages.

  18. Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Svendsen, Niels Bruun

    1992-01-01

    A method for simulation of pulsed pressure fields from arbitrarily shaped, apodized and excited ultrasound transducers is suggested. It relies on the Tupholme-Stepanishen method for calculating pulsed pressure fields, and can also handle the continuous wave and pulse-echo case. The field...... is calculated by dividing the surface into small rectangles and then Summing their response. A fast calculation is obtained by using the far-field approximation. Examples of the accuracy of the approach and actual calculation times are given...

  19. Pressurized Rover for Moon and Mars Surface Missions

    Science.gov (United States)

    Imhof, Barbara; Ransom, Stephen; Mohanty, Susmita; Özdemir, Kürsad; Häuplik-Meusburger, Sandra; Frischauf, Norbert; Hoheneder, Waltraut; Waclavicek, René

    , to assist the astronauts' field activities wherever and whenever needed. The vehicle has also been designed to have a very high degree of manoeuvrability. In addition, RAMA may be operated and replenished from a fixed site base or co-operate with other rovers of the same type to provide a mobile base. The rover in all cases will be refuelled using the products supplied by an in-situ resources facility. Transportation and surface exploration requirements defined the size and mass of the rover. RAMA has a launch mass of approximately 7000 kg, a dry mass of about 6200 kg and surface mission masses of between 7800 and 8300 kg. The rover can be launched by a future heavy lift launcher similar to the American ARES V concept. The factor most affecting the mass of the rover, other than the quantities of fuel cell reactants and crew consumables, is the amount of radiation shielding integrated in the design of the rover's pressurized shell. The factor most influencing the rover's external and internal configuration is the launcher's payload envelope and the need for the rover's centre-of-mass to be aligned with or close to the launcher's longitudinal axis. Technologies needed to support the design of the rover and its subsystems were investigated to identify the issues concerned with a possible implementation.

  20. On the pressure field of nonlinear standing water waves

    Science.gov (United States)

    Schwartz, L. W.

    1980-01-01

    The pressure field produced by two dimensional nonlinear time and space periodic standing waves was calculated as a series expansion in the wave height. The high order series was summed by the use of Pade approximants. Calculations included the pressure variation at great depth, which was considered to be a likely cause of microseismic activity, and the pressure distribution on a vertical barrier or breakwater.

  1. Characterizing developing adverse pressure gradient flows subject to surface roughness

    Science.gov (United States)

    Brzek, Brian; Chao, Donald; Turan, Özden; Castillo, Luciano

    2010-04-01

    An experimental study was conducted to examine the effects of surface roughness and adverse pressure gradient (APG) on the development of a turbulent boundary layer. Hot-wire anemometry measurements were carried out using single and X-wire probes in all regions of a developing APG flow in an open return wind tunnel test section. The same experimental conditions (i.e., T ∞, U ref, and C p) were maintained for smooth, k + = 0, and rough, k + = 41-60, surfaces with Reynolds number based on momentum thickness, 3,000 carefully designed such that the x-dependence in the flow field was known. Despite this fact, only a very small region of the boundary layer showed a balance of the various terms in the integrated boundary layer equation. The skin friction computed from this technique showed up to a 58% increase due to the surface roughness. Various equilibrium parameters were studied and the effect of roughness was investigated. The generated flow was not in equilibrium according to the Clauser (J Aero Sci 21:91-108, 1954) definition due to its developing nature. After a development region, the flow reached the equilibrium condition as defined by Castillo and George (2001), where Λ = const, is the pressure gradient parameter. Moreover, it was found that this equilibrium condition can be used to classify developing APG flows. Furthermore, the Zagarola and Smits (J Fluid Mech 373:33-79, 1998a) scaling of the mean velocity deficit, U ∞δ*/δ, can also be used as a criteria to classify developing APG flows which supports the equilibrium condition of Castillo and George (2001). With this information a ‘full APG region’ was defined.

  2. Support surface interface pressure, microenvironment, and the prevalence of pressure ulcers: an analysis of the literature.

    Science.gov (United States)

    Reger, Steven I; Ranganathan, Vinoth K; Sahgal, Vinod

    2007-10-01

    External pressure is the most frequently considered stress factor in the formation of ulcers. A review and analysis of existing literature addressing the relationship between pressure ulcer prevalence and interface pressures at various anatomic sites was conducted. Results suggest a nearly non-existent or slightly negative correlation between interface pressure and ulcer prevalence in general and spinal cord injured populations, respectively. Despite limitations of the analysis methods used, the observed lack of a direct relationship confirms the results of other studies and suggests that ulcer formation also may involve factors secondary to pressure and mechanical factors (eg, temperature, moisture, duration of the applied load, atrophy, and posture). Based on currently available information, clinicians should include these considerations when selecting a support surface. Studies directly relating primary stress factors and tissue viability with prevalence and incidence of pressure ulcers are needed to better understand the benefits of pressure-relieving support surfaces and to improve the effectiveness of prevention and treatment.

  3. Plastic collapse pressure of cylindrical vessels containing longitudinal surface cracks

    Energy Technology Data Exchange (ETDEWEB)

    Zarrabi, K. [New South Wales Univ., Sydney, NSW (Australia). Sch. of Mech. and Mfg. Eng.; Zhang, H. [New South Wales Univ., Sydney, NSW (Australia). Sch. of Mech. and Mfg. Eng.; Nhim, K. [New South Wales Univ., Sydney, NSW (Australia). Sch. of Mech. and Mfg. Eng.

    1997-05-01

    Based on nonlinear finite element analysis, the plastic collapse pressures of cylindrical vessels with longitudinal surface cracks are computed. A general formula of plastic collapse pressure of such structures are given and compared with the literature solutions. The results of the present study could be applied for the integrity assessments, failure analyses, remanent life assessment, and licence extensions of the vessels. (orig.)

  4. Molecular dynamics simulations of water on a hydrophilic silica surface at high air pressures

    DEFF Research Database (Denmark)

    Zambrano, H.A.; Walther, Jens Honore; Jaffe, R.L.

    2014-01-01

    of air in water at different pressures. Using the calibrated force field, we conduct MD simulations to study the interface between a hydrophilic silica substrate and water surrounded by air at different pressures. We find that the static water contact angle is independent of the air pressure imposed......Wepresent a force field forMolecular Dynamics (MD) simulations ofwater and air in contactwith an amorphous silica surface. We calibrate the interactions of each species present in the systemusing dedicated criteria such as the contact angle of a water droplet on a silica surface, and the solubility...... on the system. Our simulations reveal the presence of a nanometer thick layer of gas at the water–silica interface. We believe that this gas layer could promote nucleation and stabilization of surface nanobubbles at amorphous silica surfaces. © 2014 Elsevier B.V. All rights reserved....

  5. Plasma pressure and anisotropy inferred from the Tsyganenkomagnetic field model

    Directory of Open Access Journals (Sweden)

    F. Cao

    Full Text Available A numerical procedure has been developed to deduce the plasma pressure and anisotropy from the Tsyganenko magnetic field model. The Tsyganenko empirical field model, which is based on vast satellite field data, provides a realistic description of magnetic field configuration in the magnetosphere. When the force balance under the static condition is assumed, the electromagnetic J×B force from the Tsyganenko field model can be used to infer the plasma pressure and anisotropy distributions consistent with the field model. It is found that the J×B force obtained from the Tsyganenko field model is not curl-free. The curl-free part of the J×B force in an empirical field model can be balanced by the gradient of the isotropic pressure, while the nonzero curl of the J×B force can only be associated with the pressure anisotropy. The plasma pressure and anisotropy in the near-Earth plasma sheet are numerically calculated to obtain a static equilibrium consistent with the Tsyganenko field model both in the noon-midnight meridian and in the equatorial plane. The plasma pressure distribution deduced from the Tsyganenko 1989 field model is highly anisotropic and shows this feature early in the substorm growth phase. The pressure anisotropy parameter αP, defined as αP=1-PVertP, is typically ~0.3 at x ≈ -4.5RE and gradually decreases to a small negative value with an increasing tailward distance. The pressure anisotropy from the Tsyganenko 1989 model accounts for 50% of the cross-tail current at maximum and only in a highly localized region near xsim-10RE. In comparison, the plasma pressure anisotropy inferred from the Tsyganenko 1987 model is much smaller. We also find that the boundary

  6. Surface texturing of superconductors by controlled oxygen pressure

    Science.gov (United States)

    Chen, N.; Goretta, K.C.; Dorris, S.E.

    1999-01-05

    A method of manufacture of a textured layer of a high temperature superconductor on a substrate is disclosed. The method involves providing an untextured high temperature superconductor material having a characteristic ambient pressure peritectic melting point, heating the superconductor to a temperature below the peritectic temperature, establishing a reduced pO{sub 2} atmosphere below ambient pressure causing reduction of the peritectic melting point to a reduced temperature which causes melting from an exposed surface of the superconductor and raising pressure of the reduced pO{sub 2} atmosphere to cause solidification of the molten superconductor in a textured surface layer. 8 figs.

  7. Evaluating road surface conditions using dynamic tire pressure sensor

    Science.gov (United States)

    Zhao, Yubo; Wu, H. Felix; McDaniel, J. Gregory; Wang, Ming L.

    2014-03-01

    In order to best prioritize road maintenance, the level of deterioration must be known for all roads in a city's network. Pavement Condition Index (PCI) and International Roughness Index (IRI) are two standard methods for obtaining this information. However, IRI is substantially easier to measure. Significant time and money could be saved if a method were developed to estimate PCI from IRI. This research introduces a new method to estimate IRI and correlate IRI with PCI. A vehicle-mounted dynamic tire pressure sensor (DTPS) system is used. The DTPS measures the signals generated from the tire/road interaction while driving. The tire/road interaction excites surface waves that travel through the road. DTPS, which is mounted on the tire's valve stem, measures tire/road interaction by analyzing the pressure change inside the tire due to the road vibration, road geometry and tire wall vibration. The road conditions are sensible to sensors in a similar way to human beings in a car. When driving on a smooth road, tire pressure stays almost constant and there are minimal changes in the DTPS data. When driving on a rough road, DTPS data changes drastically. IRI is estimated from the reconstructed road profile using DTPS data. In order to correlate IRI with PCI, field tests were conducted on roads with known PCI values in the city of Brockton, MA. Results show a high correlation between the estimated IRI values and the known PCI values, which suggests that DTPS-based IRI can provide accurate predictions of PCI.

  8. Construction of force-free fields which have toroidal surfaces about a given surface

    International Nuclear Information System (INIS)

    Bouligand, G.

    1983-05-01

    A study of two-fields (B vector, rotB vector) of conservative flux which admits a family of toroidal surfaces of parameter phi on a domain limited by a given surface S, suggests their construction by a Cauchy-Arzela method of step by step. Taking into account the Newcomb condition this method is consistent with force-free magnetic fields and with helical equilibria with scalar pressure. The method supposes that B vector is of class C 1 . This construction makes use of the remarkable property of the field B vector to be the surface gradient of a generating multivalued function Q on a closed surface. Consequently, the initial surface will be given with its normal metric coefficient K; that is to say, B vector admits a family F of homotopic surfaces on a infinitesimal domain about S, an element of F. From this, the periodic part of Q is a solution of a Beltrami equation for the flux conservation of which numerical resolution is envisaged. The study of these fields is made in a biorthogonal system of coordinates. The coeffficients of the two fundamental metric forms of magnetic surfaces vary with phi and are interrelated by a sixth order differential system of equations which gives their variation [fr

  9. The extended surface forces apparatus. IV. Precision static pressure control.

    Science.gov (United States)

    Schurtenberger, E; Heuberger, M

    2011-10-01

    We report on design and performance of an extended surface forces apparatus (eSFA) built into a pressurized system. The aim of this instrument is to provide control over static pressure and temperature to facilitate direct surface force experiments in equilibrium with fluids at different loci of their phase diagram. We built an autoclave that can bear a miniature eSFA. To avoid mechanical or electrical feedtroughs the miniature apparatus uses an external surface coarse approach stage under ambient conditions. The surface separation is thus pre-adjusted to approximately ~3 μm before sliding the apparatus into the autoclave. Inside the autoclave, the surface separation can be further controlled with a magnetic drive at sub-Ångstrom precision over a 14 μm range. The autoclave pressure can then be set and maintained between 20 mbar and 170 bars with few mbar precision. The autoclave is connected to a specially designed pressurization system to precondition the fluids. The temperature can be controlled between -20 and 60 °C with few mK precision. We demonstrate the operation of the instrument in the case of gaseous or liquid carbon dioxide. Thanks to a consequent decoupling of the eSFA mechanical loop from the autoclave structure, the obtained measurement stability and reproducibility, at elevated pressures, is comparable to the one established for the conventional eSFA, operated under ambient conditions.

  10. The extended surface forces apparatus. IV. Precision static pressure control

    Science.gov (United States)

    Schurtenberger, E.; Heuberger, M.

    2011-10-01

    We report on design and performance of an extended surface forces apparatus (eSFA) built into a pressurized system. The aim of this instrument is to provide control over static pressure and temperature to facilitate direct surface force experiments in equilibrium with fluids at different loci of their phase diagram. We built an autoclave that can bear a miniature eSFA. To avoid mechanical or electrical feedtroughs the miniature apparatus uses an external surface coarse approach stage under ambient conditions. The surface separation is thus pre-adjusted to approximately ˜3 μm before sliding the apparatus into the autoclave. Inside the autoclave, the surface separation can be further controlled with a magnetic drive at sub-Ångstrom precision over a 14 μm range. The autoclave pressure can then be set and maintained between 20 mbar and 170 bars with few mbar precision. The autoclave is connected to a specially designed pressurization system to precondition the fluids. The temperature can be controlled between -20 and 60 °C with few mK precision. We demonstrate the operation of the instrument in the case of gaseous or liquid carbon dioxide. Thanks to a consequent decoupling of the eSFA mechanical loop from the autoclave structure, the obtained measurement stability and reproducibility, at elevated pressures, is comparable to the one established for the conventional eSFA, operated under ambient conditions.

  11. Surface cleaning of metal wire by atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Nakamura, T.; Buttapeng, C.; Furuya, S.; Harada, N.

    2009-01-01

    In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.

  12. Acoustics and Surface Pressure Measurements from Tandem Cylinder Configurations

    Science.gov (United States)

    Hutcheson, Florence V.; Brooks, Thomas F.; Lockard, David P.; Choudhari, Meelan M.; Stead, Daniel J.

    2014-01-01

    Acoustic and unsteady surface pressure measurements from two cylinders in tandem configurations were acquired to study the effect of spacing, surface trip and freestream velocity on the radiated noise. The Reynolds number ranged from 1.15x10(exp 5) to 2.17x10(exp 5), and the cylinder spacing varied between 1.435 and 3.7 cylinder diameters. The acoustic and surface pressure spectral characteristics associated with the different flow regimes produced by the cylinders' wake interference were identified. The dependence of the Strouhal number, peak Sound Pressure Level and spanwise coherence on cylinder spacing and flow velocity was examined. Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the largest and smallest cylinder spacing tested.

  13. Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

    Science.gov (United States)

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

    With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

  14. Hydrophobic and superhydrophobic surfaces fabricated using atmospheric pressure cold plasma technology: A review.

    Science.gov (United States)

    Dimitrakellis, Panagiotis; Gogolides, Evangelos

    2018-03-29

    Hydrophobic surfaces are often used to reduce wetting of surfaces by water. In particular, superhydrophobic surfaces are highly desired for several applications due to their exceptional properties such as self-cleaning, anti-icing, anti-friction and others. Such surfaces can be prepared via numerous methods including plasma technology, a dry technique with low environmental impact. Atmospheric pressure plasma (APP) has recently attracted significant attention as lower-cost alternative to low-pressure plasmas, and as a candidate for continuous rather than batch processing. Although there are many reviews on water-repellent surfaces, and a few reviews on APP technology, there are hardly any review works on APP processing for hydrophobic and superhydrohobic surface fabrication, a topic of high importance in nanotechnology and interface science. Herein, we critically review the advances on hydrophobic and superhydrophobic surface fabrication using APP technology, trying also to give some perspectives in the field. After a short introduction to superhydrophobicity of nanostructured surfaces and to APPs we focus this review on three different aspects: (1) The atmospheric plasma reactor technology used for fabrication of (super)hydrophobic surfaces. (2) The APP process for hydrophobic surface preparation. The hydrophobic surface preparation processes are categorized methodologically as: a) activation, b) grafting, c) polymerization, d) roughening and hydrophobization. Each category includes subcategories related to different precursors used. (3) One of the most important sections of this review concerns superhydrophobic surfaces fabricated using APP. These are methodologically characterized as follows: a) single step processes where micro-nano textured topography and low surface energy coating are created at the same time, or b) multiple step processes, where these steps occur sequentially in or out of the plasma. We end the review with some perspectives in the field. We

  15. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    irradiation, the water contact angle dropped markedly, and tended to decrease furthermore at higher power. The ultrasonic irradiation during the plasma treatment consistently improved the wettability. Oxygen containing polar functional groups were introduced at the surface by the plasma treatment......Atmospheric pressure plasma treatment can be highly enhanced by simultaneous high-power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above approximately 140 dB can reduce the thickness of a boundary gas layer between the plasma...... are separated using a polyethylene film. The gliding arc was extended by a high speed air flow into ambient air, directed the polyester surface at an angle of approximately 30o. The ultrasonic waves were introduced vertically to the surface. After the plasma treatment using each plasma source without ultrasonic...

  16. Are pressure redistribution surfaces or heel protection devices effective for preventing heel pressure ulcers?

    Science.gov (United States)

    Junkin, Joan; Gray, Mikel

    2009-01-01

    Heel pressure ulcers are recognized as second in prevalence only to pressure ulcer (PU) on the heel among hospitalized patients, and recent studies suggest their incidence may be higher than even sacral ulcers. We systematically reviewed the literature to identify and evaluate whether pressure redistribution surfaces or heel protection devices are effective for the prevention of heel ulcers. We searched CINAHL and MEDLINE databases, using the keywords "pressure ulcer" and "heel," which we also searched the Cochrane Library, using the key terms "pressure ulcer," "heel," and "support surface." We hand searched the ancestry of pertinent research reports and review articles in order to identify additional studies. Inclusion criteria were (1) any study that compared one or more pressure redistribution surfaces or heel protection devices designed specifically to prevent heel PU and (2) any study comparing 2 or more pressure redistribution surfaces designed to prevent PU that specifically reported differences in the incidence of heel PU. Exclusion criteria were (1) studies that did not measure heel PU incidence as an outcome, (2) studies without an English language abstract, and (3) studies that reported overall PU incidence but did not analyze heel PU incidence separately. Clinical evidence concerning the efficacy of pressure redistribution surfaces or heel protection devices is sparse. Existing evidence suggests that pressure redistribution surfaces vary in their ability to prevent heel pressure ulcers, but there is insufficient evidence to determine which surfaces are optimal for this purpose. A single study suggests that a wedge-shaped viscoelastic foam cushion is superior to standard foam pillows for preventing heel PU, but further research is needed before a definitive conclusion concerning this issue can be reached. There is insufficient evidence to determine whether heel protection devices are more effective than a standard hospital foam pillow for the prevention

  17. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    2012-01-01

    Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasma...... arc at atmospheric pressure to study adhesion improvement. The effect of ultrasonic irradiation with the frequency diapason between 20 and 40 kHz at the SPL of ∼150 dB was investigated. After the plasma treatment without ultrasonic irradiation, the wettability was significantly improved....... The ultrasonic irradiation during the plasma treatment consistently enhanced the treatment efficiency. The principal effect of ultrasonic irradiation can be attributed to enhancing surface oxidation during plasma treatment. In addition, ultrasonic irradiation can suppress arcing, and the uniformity...

  18. Drop impact on a solid surface at reduced air pressure

    Science.gov (United States)

    Langley, Kenneth; Li, E. Q.; Tian, Y. S.; Hicks, P. D.; Thoroddsen, S. T.

    2017-11-01

    When a drop approaches a solid surface at atmospheric pressure, the lubrication pressure within the air forms a dimple in the bottom of the drop resulting in the entrainment of an air disc upon impact. Reducing the ambient air pressure below atmospheric has been shown to suppress splashing and the compression of the intervening air could be significant on the air disc formation; however, to date there have been no experimental studies showing how the entrainment of the air disc is affected by reducing the ambient pressure. Using ultra-high-speed interferometry, at up to 5 Mfps, we investigate droplet impacts onto dry solid surfaces in reduced ambient air pressures with particular interest in what happens as rarified gas effects become important, i.e. when the thickness of the air layer is of the same magnitude as the mean free path of the air molecules. Experimental data will be presented showing novel phenomena and comparisons will be drawn with theoretical models from the literature.

  19. Dynamic of vapor bubble growth in fields of variable pressure

    International Nuclear Information System (INIS)

    Pedroso, H.K.

    1982-01-01

    A mathematical model for the description of the growth from an initial nucleus of a vapor bubble imersed in liquid, subjected to a loss of pressure is presented. The model is important for analysing LOCA (Loss of Coolant Acident) in P.W.R. type reactors. Several simplifications were made in the phenomenum governing equations. With such simplifications the heat diffusion equation became the determining factor for the bubble growth, and the problem was reduced to solve the heat diffusion equation for semi infinite solid whose surface temperature is a well known function of time (it is supposed that the surface temperature is equal to the saturation temperature of the liquid at the system pressure at a given moment). The model results in an analytical expression for the bubble radius as a function of time. Comparisons with experimental data and previous models were made, with reasonable agreement. (author) [pt

  20. Pressure Field Study of the Tevatron Cold Compressors

    International Nuclear Information System (INIS)

    Klebaner, A.L.; Martinez, A.; Soyars, W.M.; Theilacker, J.C.

    2004-01-01

    The Fermilab Tevatron cryogenic system utilizes high-speed centrifugal cold compressors, manufactured by Ishikawajima-Harima Heavy Industries Co. Ltd. (IHI), for high-energy operations. The compressor is designed to pump 60 g/sec of 3.6 K saturated helium vapor at a pressure ratio of 2.8, with an off-design range of 40 to 70 g/sec. Operating speeds are between 40,000 and 95,000 rpm, with a speed of 80,000 rpm at the design point. Different heat loads and magnet quench performance of each of the twenty-four satellite refrigerators dictates different process pressure and flow rates of the cold compressors. Reducing the process flow rate can cause the centrifugal cold compressor to stop pumping and subsequently surge. Tests have been conducted at the Cryogenic Test Facility at Fermilab to map the pressure field and appropriate efficiency of the IHI hydrodynamic cold compressor. The information allows tuning of each of the twenty-four Tevatron satellite refrigerators to avoid cold compressor operation near the surge and choke lines. A new impeller has also been tested. The Tevatron cold compressor pressure field and efficiency data with the new impeller are presented in this paper

  1. Simulations of pressure and salinity fields at Aespoe

    Energy Technology Data Exchange (ETDEWEB)

    Loefman, J. [VTT Energy, Espoo (Finland)

    1997-04-01

    The primary objective of this study was to examine whether the geochemical field data from Aespoe could be interpreted and understood by means of numerical simulations for flow and transport. A site-specific simulation model for groundwater flow and salt transport was developed on the basis of the field investigations. Both steady-state and transient simulations of flow and transport were performed. In the transient simulations, land uplift and the effect of diffusion into/from the matrix blocks with stagnant water were taken into account. The computational results were evaluated on the basis of the experimental values for the pressure and salt concentration.

  2. Variation of surface electric field during geomagnetic disturbed ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 124; Issue 8. Variation of surface electric field ... Diurnal variation of surface electric field measured at Maitri shows a similar variation with worldwide thunderstorm activity, whereas the departure of the field is observed during disturbed periods. This part of the field ...

  3. Atmospheric pressure plasma surface modification of carbon fibres

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Michelsen, Poul

    2008-01-01

    Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He....../O2 and Ar plasma treatments, mainly attributed to an increase in the density of the C-O single bond at the carbon fibre surfaces. The O/C ratio increased to 0.182 after 1-s He plasma treatment, and remained approximately constant after longer treatment. After exposure in an ambient air at room...

  4. Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

    Science.gov (United States)

    Watkins, A. Neal; Leighty, Bradley; Lipford, William E.; Wong, Oliver D.; Goodman, Kyle Z.; Crafton, Jim; Forlines, Alan; Goss, Larry P.; Gregory, James W.; Juliano, Thomas J.

    2012-01-01

    This paper will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. Preliminary results show that the PSP agrees both qualitatively and quantitatively with both the expected results as well as with the pressure taps. Several areas of improvement have been indentified and are currently being developed.

  5. Sound pressure around dipole source above porous surface.

    Science.gov (United States)

    Prezelj, Jurij; Steblaj, Peter; Cudina, Mirko

    2014-06-01

    A technique for in situ measurements of acoustic properties of a fibrous porous material is proposed in this paper. Proposed technique exploits a directivity pattern of a dipole source in its very near field. Theoretical analysis for the proposed technique is based on the Rayleigh integral with a complex reflection included. Results are compared with results of FEM analysis and show that flow resistivity of a porous material placed in the very near field of the dipole source has significant influence on the sound pressure at its ring. Results provide an excellent starting point for the design of the sensor for sound absorption.

  6. Pressure-Redistributing Support Surface Use and Pressure Ulcer Incidence in Elderly Hip Fracture Patients

    Science.gov (United States)

    Rich, Shayna E.; Shardell, Michelle; Hawkes, William G.; Margolis, David J.; Amr, Sania; Miller, Ram; Baumgarten, Mona

    2013-01-01

    OBJECTIVES To evaluate the association between pressure-redistributing support surface (PRSS) use and incident pressure ulcers in older adults with hip fracture. DESIGN Secondary analysis of data from prospective cohort with assessments performed as soon as possible after hospital admission and on alternating days for 21 days. SETTING Nine hospitals in the Baltimore Hip Studies network and 105 postacute facilities to which participants were discharged. PARTICIPANTS Six hundred fifty-eight people aged 65 and older who underwent surgery for hip fracture. MEASUREMENTS Full-body examination for pressure ulcers; bedbound status; and PRSS use, recorded as none, powered (alternating pressure mattresses, low-air-loss mattresses, and alternating pressure overlays), or nonpowered (high-density foam, static air, or gel-filled mattresses or pressure-redistributing overlays except for alternating pressure overlays). RESULTS Incident pressure ulcers (IPUs), Stage 2 or higher, were observed at 4.2% (195/4,638) of visits after no PRSS use, 4.5% (28/623) of visits after powered PRSS use, and 3.6% (54/1,496) of visits after nonpowered PRSS use. The rate of IPU per person-day of follow-up did not differ significantly between participants using powered PRSSs and those not using PRSSs. The rate also did not differ significantly between participants using nonpowered PRSSs and those not using PRSSs, except in the subset of bedbound participants (incidence rate ratio = 0.3, 95% confidence interval = 0.1–0.7). CONCLUSION PRSS use was not associated with a lower IPU rate. Clinical guidelines may need revision for the limited effect of PRSS use, and it may be appropriate to target PRSS use to bedbound patients at risk of pressure ulcers. PMID:21649630

  7. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin

    2012-01-01

    separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...... and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance......In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field...

  8. Field dependent surface resistance of niobium on copper cavities

    Directory of Open Access Journals (Sweden)

    T. Junginger

    2015-07-01

    Full Text Available The surface resistance R_{S} of superconducting cavities prepared by sputter coating a niobium film on a copper substrate increases significantly stronger with the applied rf field compared to cavities of bulk material. A possible cause is that the thermal boundary resistance between the copper substrate and the niobium film induces heating of the inner cavity wall, resulting in a higher R_{S}. Introducing helium gas in the cavity, and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by less than 120 mK when R_{S} increases with E_{acc} by 100  nΩ. This is more than one order of magnitude less than what one would expect from global heating. Additionally, the effects of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for the current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered R_{S}.

  9. On the Pressure Distribution in a Porous Media under a Spherical Loading Surface

    Science.gov (United States)

    Wang, Qiuyun; Zhu, Zenghao; Nathan, Rungun; Wu, Qianhong

    2017-11-01

    The phenomenon of pressure generation and relaxation inside a porous media is widely observed in biological systems. Herein, we report a biomimetic study to examine the pressure distribution inside a soft porous layer when a spherical loaded surface suddenly impacts on it. A novel experimental setup was developed that includes a fully instrumented spherical piston and a soft fibrous porous layer underneath. Extensive experimental study was performed with different porous materials, different loadings and different sized loading surfaces. The pore pressure generation and the motion of the loading surface were recorded. A novel theoretical model was developed to characterize the pressure field during the process. Excellent agreement was observed between the experimental results and the theoretically predictions. It shows that the pressure generation is governed by the Brinkman parameter, α = h/Kp0.5, where h is the porous layer thickness, and Kp is the undeformed permeability. The study improves our understanding of the dynamic response of soft porous media under rapid compression. It has board impact on the study of transient load bearing in biological systems and industry applications. This work was supported by the National Science Foundation (NSF CBET) under Award #1511096.

  10. [Measurements of surface ocean carbon dioxide partial pressure during WOCE

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This paper discusses the research progress of the second year of research under Measurement of Surface Ocean Carbon Dioxide Partial Pressure During WOCE'' and proposes to continue measurements of underway pCO[sub 2]. During most of the first year of this grant, our efforts to measure pCO[sub 2] on WOCE WHP legs were frustrated by ship problems. The R/V Knorr, which was originally scheduled to carry out the first work on WHP lines P19 and P16 in the southeastem Pacific during the 1990-91 austral summer, was delayed in the shipyard during her mid-life refit for more than a year. In the interim, the smaller R/V Thomas Washington, was pressed into service to carry out lower-latitude portions of WHP lines P16 and P17 during mid-1991 (TUNES Expedition). We installed and operated our underway chromatographic system on this expedition, even though space and manpower on this smaller vessel were limited and no one from our group would be aboard any of the 3 WHP expedition legs. The results for carbon dioxide and nitrous oxide are shown. A map of the cruise track is shown for each leg, marked with cumulative distance. Following each track is a figure showing the carbon dioxide and nitrous oxide results as a function of distance along this track. The results are plotted as dry-gas mole fractions (in ppm and ppb, respectively) in air and in gas equilibrated with surface seawater at a total pressure equal to the barometric pressure. The air data are plotted as a 10-point running mean, and appear as a roughly horizontal line. The seawater data are plotted as individual points, using a 5-point Gaussian smoother. Equal values Of xCO[sub 2] in air and surface seawater indicate air-sea equilibrium.

  11. Field emission from the surface of highly ordered pyrolytic graphite

    Energy Technology Data Exchange (ETDEWEB)

    Knápek, Alexandr, E-mail: knapek@isibrno.cz [Institute of Scientific Instruments of the ASCR, v.v.i., Královopolská 147, Brno (Czech Republic); Sobola, Dinara; Tománek, Pavel [Department of Physics, FEEC, Brno University of Technology, Technická 8, Brno (Czech Republic); Pokorná, Zuzana; Urbánek, Michal [Institute of Scientific Instruments of the ASCR, v.v.i., Královopolská 147, Brno (Czech Republic)

    2017-02-15

    Highlights: • HOPG shreds were created and analyzed in the UHV conditions. • Current-voltage measurements have been done to confirm electron tunneling, based on the Fowler-Nordheim theory. • Surface was characterized by other surface evaluation methods, in particular by: SNOM, SEM and AFM. - Abstract: This paper deals with the electrical characterization of highly ordered pyrolytic graphite (HOPG) surface based on field emission of electrons. The effect of field emission occurs only at disrupted surface, i.e. surface containing ripped and warped shreds of the uppermost layers of graphite. These deformations provide the necessary field gradients which are required for measuring tunneling current caused by field electron emission. Results of the field emission measurements are correlated with other surface characterization methods such as scanning near-field optical microscopy (SNOM) or atomic force microscopy.

  12. The dependence of lipid monolayer lipolysis on surface pressure.

    OpenAIRE

    Hall, D G

    1992-01-01

    Brönsted-Bjerrum theory [Brönsted (1922) Z. Phys. Chem. 102, 169-207; (1925) Z. Phys. Chem. 115, 337-364; Bjerrum (1924) Z. Phys. Chem. 108, 82-100] as applied to reactions at interfaces is used to interpret published data on the lipolysis of dinonanoyl phosphatidylcholine monolayers by pancreatic phospholipase A2. Reasonable quantitative agreement between theoretical and experimental results occurs when the reported effects of surface pressure on the amount of adsorbed enzyme are used togeth...

  13. Osmotic pressure of the cutaneous surface fluid of Rana esculenta

    DEFF Research Database (Denmark)

    Hviid Larsen, Erik; Ramløv, Hans

    2012-01-01

    The osmotic pressure of the cutaneous surface fluid (CSF) in vivo was measured for investigating whether evaporative water loss (EWL) derives from water diffusing through the skin or fluid secreted by exocrine subepidermal mucous glands. EWL was stimulated by subjecting R. esculenta to 30–34 °C....../Kg, n = 16. Osmolality of lymph was, 239 ± 4 mosmol/Kg, n = 8. Thus the flow of water across the epidermis would be in the direction from CSF to the interstitial fluid driven by the above osmotic gradients and/or coupled to the inward active Na+ flux via the slightly hyperosmotic paracellular...

  14. Cubic helimagnets in magnetic field and at pressure

    International Nuclear Information System (INIS)

    Maleyev, S.V.

    2009-01-01

    Cubic helimagnets with B20 structure display several unusual properties such as anisotropy of the spin-wave spectrum al small momenta q, rotation of the helix vector k in magnetic field and quantum phase transition at pressure. We demonstrate that first two phenomena are a result of umklapp processes mixing excitations with momenta q, q+k and q-k. At very low magnetic field perpendicular to k the helical structure remains stable due to spin-wave gap Δ. Its square is sum of two parts. The first one is a result of the magnon interaction and the second negative part stems from magneto-elastic interaction. It is suggested that competition between these parts leads to the quantum phase transition observed in MnSi and FeGe. For MnSi from rough estimations at ambient pressure was shown that both parts are comparable with the experimentally observed gap. The magneto-elastic interaction is also responsible for 2k modulation of the lattice and contributes to the magnetic anisotropy. Experimental observation by X-ray and neutron scattering of this lattice modulation allows to determine the strength of the magneto-elastic interaction responsible for above phenomena and the lattice helicity

  15. The Effect of 200 MPa Pressure on Specific Surface Area of Clay

    Directory of Open Access Journals (Sweden)

    Koszela-Marek Ewa

    2015-02-01

    Full Text Available The paper presents the results of laboratory studies of the 200 MPa pressure effect on specific surface area of clay. The original high-pressure investigation stand was used for the pressure tests. Determination of the specific surface area was performed by the methylene blue adsorption method. The results of the specific surface area test were compared for non-pressurized clays and for clays pressured in a high-pressure chamber. It was found that the specific surface area of pressurized soil clearly increased. This shows that some microstructural changes take place in the soil skeleton of clays.

  16. Error Propagation Dynamics of PIV-based Pressure Field Calculations: How well does the pressure Poisson solver perform inherently?

    Science.gov (United States)

    Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd

    2016-08-01

    Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type.

  17. Error propagation dynamics of PIV-based pressure field calculations: How well does the pressure Poisson solver perform inherently?

    International Nuclear Information System (INIS)

    Pan, Zhao; Thomson, Scott; Whitehead, Jared; Truscott, Tadd

    2016-01-01

    Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type. (paper)

  18. Error Propagation Dynamics of PIV-based Pressure Field Calculations: How well does the pressure Poisson solver perform inherently?

    Science.gov (United States)

    Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd

    2016-01-01

    Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measure the error through experiment, we investigate the dynamics of the error propagation by examining the Poisson equation directly. We analytically quantify the error bound in the pressure field, and are able to illustrate the mathematical roots of why and how the Poisson equation based pressure calculation propagates error from the PIV data. The results show that the error depends on the shape and type of boundary conditions, the dimensions of the flow domain, and the flow type. PMID:27499587

  19. Enhanced Field Emission Studies on Niobium Surfaces Relevant to High Field Superconducting Radio-Frequency Devices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tong [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2002-09-18

    Enhanced field emission (EFE) presents the main impediment to higher acceleration gradients in superconducting niobium (Nb) radiofrequency cavities for particle accelerators. The strength, number and sources of EFE sites strongly depend on surface preparation and handling. The main objective of this thesis project is to systematically investigate the sources of EFE from Nb, to evaluate the best available surface preparation techniques with respect to resulting field emission, and to establish an optimized process to minimize or eliminate EFE. To achieve these goals, a scanning field emission microscope (SFEM) was designed and built as an extension to an existing commercial scanning electron microscope (SEM). In the SFEM chamber of ultra high vacuum, a sample is moved laterally in a raster pattern under a high voltage anode tip for EFE detection and localization. The sample is then transferred under vacuum to the SEM chamber equipped with an energy-dispersive x-ray spectrometer for individual emitting site characterization. Compared to other systems built for similar purposes, this apparatus has low cost and maintenance, high operational flexibility, considerably bigger scan area, as well as reliable performance. EFE sources from planar Nb have been studied after various surface preparation, including chemical etching and electropolishing, combined with ultrasonic or high-pressure water rinse. Emitters have been identified, analyzed and the preparation process has been examined and improved based on EFE results. As a result, field-emission-free or near field-emission-free surfaces at ~140 MV/m have been consistently achieved with the above techniques. Characterization on the remaining emitters leads to the conclusion that no evidence of intrinsic emitters, i.e., no fundamental electric field limit induced by EFE, has been observed up to ~140 MV/m. Chemically etched and electropolished Nb are compared and no significant difference is observed up to ~140 MV/m. To

  20. Surface field theories of point group symmetry protected topological phases

    Science.gov (United States)

    Huang, Sheng-Jie; Hermele, Michael

    2018-02-01

    We identify field theories that describe the surfaces of three-dimensional bosonic point group symmetry protected topological (pgSPT) phases. The anomalous nature of the surface field theories is revealed via a dimensional reduction argument. Specifically, we study three different surface field theories. The first field theory is quantum electrodynamics in three space-time dimensions (QED3) with four flavors of fermions. We show this theory can describe the surfaces of a majority of bosonic pgSPT phases protected by a single mirror reflection, or by Cn v point group symmetry for n =2 ,3 ,4 ,6 . The second field theory is a variant of QED3 with charge-1 and charge-3 Dirac fermions. This field theory can describe the surface of a reflection symmetric pgSPT phase built by placing an E8 state on the mirror plane. The third field theory is an O (4 ) nonlinear sigma model with a topological theta term at θ =π , or, equivalently, a noncompact CP1 model. Using a coupled wire construction, we show this is a surface theory for bosonic pgSPT phases with U (1 ) ×Z2P symmetry. For the latter two field theories, we discuss the connection to gapped surfaces with topological order. Moreover, we conjecture that the latter two field theories can describe surfaces of more general bosonic pgSPT phases with Cn v point group symmetry.

  1. Feature Surfaces in Symmetric Tensor Fields Based on Eigenvalue Manifold.

    Science.gov (United States)

    Palacios, Jonathan; Yeh, Harry; Wang, Wenping; Zhang, Yue; Laramee, Robert S; Sharma, Ritesh; Schultz, Thomas; Zhang, Eugene

    2016-03-01

    Three-dimensional symmetric tensor fields have a wide range of applications in solid and fluid mechanics. Recent advances in the (topological) analysis of 3D symmetric tensor fields focus on degenerate tensors which form curves. In this paper, we introduce a number of feature surfaces, such as neutral surfaces and traceless surfaces, into tensor field analysis, based on the notion of eigenvalue manifold. Neutral surfaces are the boundary between linear tensors and planar tensors, and the traceless surfaces are the boundary between tensors of positive traces and those of negative traces. Degenerate curves, neutral surfaces, and traceless surfaces together form a partition of the eigenvalue manifold, which provides a more complete tensor field analysis than degenerate curves alone. We also extract and visualize the isosurfaces of tensor modes, tensor isotropy, and tensor magnitude, which we have found useful for domain applications in fluid and solid mechanics. Extracting neutral and traceless surfaces using the Marching Tetrahedra method can cause the loss of geometric and topological details, which can lead to false physical interpretation. To robustly extract neutral surfaces and traceless surfaces, we develop a polynomial description of them which enables us to borrow techniques from algebraic surface extraction, a topic well-researched by the computer-aided design (CAD) community as well as the algebraic geometry community. In addition, we adapt the surface extraction technique, called A-patches, to improve the speed of finding degenerate curves. Finally, we apply our analysis to data from solid and fluid mechanics as well as scalar field analysis.

  2. Pressure RElieving Support SUrfaces: a Randomised Evaluation 2 (PRESSURE 2): study protocol for a randomised controlled trial

    OpenAIRE

    Brown, Sarah; Smith, Isabelle L.; Brown, Julia M.; Hulme, Claire; McGinnis, Elizabeth; Stubbs, Nikki; Nelson, E. Andrea; Muir, Delia; Rutherford, Claudia; Walker, Kay; Henderson, Valerie; Wilson, Lyn; Gilberts, Rachael; Collier, Howard; Fernandez, Catherine

    2016-01-01

    Background Pressure ulcers represent a major burden to patients, carers and the healthcare system, affecting approximately 1 in 17 hospital and 1 in 20 community patients. They impact greatly on an individual?s functional status and health-related quality of life. The mainstay of pressure ulcer prevention practice is the provision of pressure redistribution support surfaces and patient repositioning. The aim of the PRESSURE 2 study is to compare the two main mattress types utilised within the...

  3. Lunar electric fields, surface potential and associated plasma sheaths

    Science.gov (United States)

    Freeman, J. W.; Ibrahim, M.

    1975-01-01

    A review is given of studies of the electric-field environment of the moon. Surface electric potentials are reported for the dayside and terminator regions, electron and ion densities in the plasma sheath adjacent to each surface-potential regime are evaluated, and the corresponding Debye lengths are estimated. The electric fields, which are approximated by the surface potential over the Debye length, are shown to be at least three orders of magnitude higher than the pervasive solar-wind electric field and to be confined to within a few tens of meters of the lunar surface.

  4. Zeeman Field-``Rotated'' Transitions for Surface Chern Insulators

    Science.gov (United States)

    Mele, E. J.; Zhang, Fan; Li, Xiao; Feng, Ji; Kane, C. L.

    2014-03-01

    Mirror symmetric surfaces of a topological crystalline insulator (e.g. SnTe) host even number of Dirac surface states. A surface Zeeman field generically gaps these states leading to a quantized anomalous Hall effect. Varying the direction of Zeeman field induces transitions between different surface insulating states with any two Chern numbers between -4 and 4. In the crystal frame the phase boundaries occur for field orientations which are great circles with (111)-like normals on a sphere. [arXiv:1309.7682

  5. Pair-breaking effects by parallel magnetic field in electric-field-induced surface superconductivity

    Science.gov (United States)

    Nabeta, Masahiro; Tanaka, Kenta K.; Onari, Seiichiro; Ichioka, Masanori

    2016-11-01

    We study paramagnetic pair-breaking in electric-field-induced surface superconductivity, when magnetic field is applied parallel to the surface. The calculation is performed by Bogoliubov-de Gennes theory with s-wave pairing, including the screening effect of electric fields by the induced carriers near the surface. Due to the Zeeman shift by applied fields, electronic states at higher-level sub-bands become normal-state-like. Therefore, the magnetic field dependence of Fermi-energy density of states reflects the multi-gap structure in the surface superconductivity.

  6. Gaussian vector fields on triangulated surfaces

    DEFF Research Database (Denmark)

    Ipsen, John H

    2016-01-01

    proven to be very useful to resolve the complex interplay between in-plane ordering of membranes and membrane conformations. In the present work we have developed a procedure for realistic representations of Gaussian models with in-plane vector degrees of freedoms on a triangulated surface. The method...

  7. Electric fields associated with transient surface currents

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1992-01-01

    The boundary condition to be fulfilled by the potential functions associated with a transient surface current is derived and expressed in terms of generalized orthogonal coordinates. From the analysis, it can be deduced that the use of the method of separation of variables is restricted to three ...

  8. Field-ion microscope with plasma preparation of specimen surface

    International Nuclear Information System (INIS)

    Suvorov, A.L.; Bobkov, A.F.; Kasatkin, V.A.; Zaitsev, S.V.

    1986-01-01

    This paper presents a method for preparing specimen surfaces for field-ion microscope analysis, in which a brief gas discharge is initiated near the surface under study with simultaneous pulse evaporation by the field of the material of the specimen itself or desorption of foreign atoms and molecular complexes from its surface. The method considerably increases the efficiency of structure analysis of conducting materials in a field-ion microscope. An all-metal field-ion microscope is developed for implementation of the method

  9. Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry

    Science.gov (United States)

    Winslow, Reka M.; Johnson, Catherine L.; Anderson, Brian J.; Gershman, Daniel J.; Raines, Jim M.; Lillis, Robert J.; Korth, Haje; Slavin, James A.; Solomon, Sean C.; Zurbuchen, Thomas H.; hide

    2014-01-01

    Solar wind protons observed by the MESSENGER spacecraft in orbit about Mercury exhibit signatures of precipitation loss to Mercury's surface. We apply proton-reflection magnetometry to sense Mercury's surface magnetic field intensity in the planet's northern and southern hemispheres. The results are consistent with a dipole field offset to the north and show that the technique may be used to resolve regional-scale fields at the surface. The proton loss cones indicate persistent ion precipitation to the surface in the northern magnetospheric cusp region and in the southern hemisphere at low nightside latitudes. The latter observation implies that most of the surface in Mercury's southern hemisphere is continuously bombarded by plasma, in contrast with the premise that the global magnetic field largely protects the planetary surface from the solar wind.

  10. Measuring Global Surface Pressures on a Circulation Control Concept Using Pressure Sensitive Paint

    Science.gov (United States)

    Watkins, Anthony N.; Lipford, William E.; Leighty, Bradley D.; Goodman, Kyle Z.; Goad, William K.

    2012-01-01

    This report will present the results obtained from the Pressure Sensitive Paint (PSP) technique on a circulation control concept model. This test was conducted at the National Transonic Facility (NTF) at the NASA Langley Research Center. PSP was collected on the upper wing surface while the facility was operating in cryogenic mode at 227 K (-50 oF). The test envelope for the PSP portion included Mach numbers from 0.7 to 0.8 with angle of attack varying between 0 and 8 degrees and a total pressure of approximately 168 kPa (24.4 psi), resulting in a chord Reynolds number of approximately 15 million. While the PSP results did exhibit high levels of noise in certain conditions (where the oxygen content of the flow was very small), some conditions provided good correlation between the PSP and pressure taps, showing the ability of the PSP technique. This work also served as a risk reduction opportunity for future testing in cryogenic conditions at the NTF.

  11. Surface wave propagation characteristics in atmospheric pressure plasma column

    International Nuclear Information System (INIS)

    Pencheva, M; Benova, E; Zhelyazkov, I

    2007-01-01

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance

  12. Atmospheric pressure dielectric barrier discharges for sterilization and surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chin, O. H.; Lai, C. K.; Choo, C. Y.; Wong, C. S.; Nor, R. M. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Thong, K. L. [Microbiology Division, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-04-24

    Atmospheric pressure non-thermal dielectric barrier discharges can be generated in different configurations for different applications. For sterilization, a parallel-plate electrode configuration with glass dielectric that discharges in air was used. Gram-negative bacteria (Escherichia coli and Salmonella enteritidis) and Gram-positive bacteria (Bacillus cereus) were successfully inactivated using sinusoidal high voltage of ∼15 kVp-p at 8.5 kHz. In the surface treatment, a hemisphere and disc electrode arrangement that allowed a plasma jet to be extruded under controlled nitrogen gas flow (at 9.2 kHz, 20 kVp-p) was applied to enhance the wettability of PET (Mylar) film.

  13. Impact of magnetic fields on ram pressure stripping in disk galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Ruszkowski, M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Brüggen, M. [Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany); Lee, D. [The Flash Center for Computational Science, The University of Chicago, 5747 South Ellis, Chicago, IL 60637 (United States); Shin, M.-S., E-mail: mateuszr@umich.edu [Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)

    2014-03-20

    Ram pressure stripping can remove significant amounts of gas from galaxies in clusters and massive groups and thus has a large impact on the evolution of cluster galaxies. Recent observations have shown that key properties of ram-pressure-stripped tails of galaxies, such as their width and structure, are in conflict with predictions by simulations. To increase the realism of existing simulations, we simulated for the first time a disk galaxy exposed to a uniformly magnetized wind including radiative cooling and self-gravity of the gas. We find that magnetic fields have a strong effect on the morphology of the gas in the tail of the galaxy. While in the purely hydrodynamical case the tail is very clumpy, the magnetohydrodynamical case shows very filamentary structures in the tail. The filaments can be strongly supported by magnetic pressure and, wherever this is the case, the magnetic fields vectors tend to be aligned with the filaments. The ram pressure stripping process may lead to the formation of magnetized density tails that appear as bifurcated in the plane of the sky and resemble the double tails observed in ESO 137-001 and ESO 137-002. Such tails can be formed under a variety of situations, both for the disks oriented face-on with respect to the intracluster medium (ICM) wind and for the tilted ones. While this bifurcation is the consequence of the generic tendency for the magnetic fields to produce very filamentary tail morphology, the tail properties are further shaped by the combination of the magnetic field orientation and the sliding of the field past the disk surface exposed to the wind. Despite the fact that the effect of the magnetic field on the morphology of the tail is strong, magnetic draping does not strongly change the rate of gas stripping. For a face-on galaxy, the field tends to reduce the amount of gas stripping compared to the pure hydrodynamical case, and is associated with the formation of a stable magnetic draping layer on the side of

  14. Randomised, controlled trial of alternating pressure mattresses compared with alternating pressure overlays for the prevention of pressure ulcers: PRESSURE (pressure relieving support surfaces) trial

    OpenAIRE

    2006-01-01

    Objective To compare whether differences exist between alternating pressure overlays and alternating pressure mattresses in the development of new pressure ulcers, healing of existing pressure ulcers, and patient acceptability. Design Pragmatic, open, multicentre, randomised controlled trial. Setting 11 hospitals in six NHS trusts. Participants 1972 people admitted to hospital as acute or elective patients. Interventions Participants were randomised to an alternating pressure mattress (n = 98...

  15. Surface modification with a remote atmospheric pressure plasma: dc glow discharge and surface streamer regime

    International Nuclear Information System (INIS)

    Temmerman, Eef; Akishev, Yuri; Trushkin, Nikolay; Leys, Christophe; Verschuren, Jo

    2005-01-01

    A remote atmospheric pressure discharge working with ambient air is used for the near room temperature treatment of polymer foils and textiles of varying thickness. The envisaged plasma effect is an increase in the surface energy of the treated material, leading, e.g., to a better wettability or adhesion. Changes in wettability are examined by measuring the contact angle or the liquid absorptive capacity. Two regimes of the remote atmospheric pressure discharge are investigated: the glow regime and the streamer regime. These regimes differ mainly in power density and in the details of the electrode design. The results show that this kind of discharge makes up a convenient non-thermal plasma source to be integrated into a treatment installation working at atmospheric pressure

  16. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    Science.gov (United States)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1δg), and 2.9 x 10^12 cm-3 O2(^1σ^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1δg) metastables were responsible for killing the anthrax and other microorganisms.

  17. Characteristics of meter-scale surface electrical discharge propagating along water surface at atmospheric pressure

    Czech Academy of Sciences Publication Activity Database

    Hoffer, Petr; Sugiyama, Y.; Hosseini, S.H.R.; Akiyama, H.; Lukeš, Petr; Akiyama, M.

    2016-01-01

    Roč. 49, č. 41 (2016), č. článku 415202. ISSN 0022-3727 Institutional support: RVO:61389021 Keywords : water surface * spectroscopy * high-speed photography * pulsed plasma discharge * Atmospheric-pressure plasmas * electric discharges * liquids * water Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/0022-3727/49/41/415202

  18. Nanotomography of Cell Surfaces with Evanescent Fields

    Directory of Open Access Journals (Sweden)

    Michael Wagner

    2008-01-01

    Full Text Available The technique of variable-angle total internal reflection fluorescence microscopy (TIRFM and its application to nanotomography of cell surfaces are described. Present applications include (1 3D imaging of chromosomes in their metaphase to demonstrate axial resolution in the nanometre range, (2 measurements of cell-substrate topology, which upon cholesterol depletion shows some loosening of cell-substrate contacts, and (3 measurements of cell topology upon photodynamic therapy (PDT, which demonstrate cell swelling and maintenance of focal contacts. The potential of the method for in vitro diagnostics, but also some requirements and limitations are discussed.

  19. Temperature effects on surface pressure-induced changes in rat skin perfusion: implications in pressure ulcer development.

    Science.gov (United States)

    Patel, S; Knapp, C F; Donofrio, J C; Salcido, R

    1999-07-01

    The effect of varying local skin temperature on surface pressure-induced changes in skin perfusion and deformation was determined in hairless fuzzy rats (13.5+/-3 mo, 474+/-25 g). Skin surface pressure was applied by a computer-controlled plunger with corresponding skin deformation measured by a linear variable differential transformer while a laser Doppler flowmeter measured skin perfusion. In Protocol I, skin surface perfusion was measured without heating (control, T=28 degrees C), with heating (T=36 degrees C), for control (probe just touching skin, 3.7 mmHg), and at two different skin surface pressures, 18 mmHg and 73 mmHg. Heating caused perfusion to increase at control and 18 mmHg pressure, but not at 73 mmHg. In Protocol II, skin perfusion was measured with and without heating as in Protocol I, but this time skin surface pressure was increased from 3.7 to 62 mmHg in increments of 3.7 mmHg. For unheated skin, perfusion increased as skin surface pressure increased from 3.7 to 18 mmHg. Further increases in surface pressure caused a decrease in perfusion until zero perfusion was reached for pressures over 55 mmHg. Heating increased skin perfusion for surface pressures from 3.7 to 18 mmHg, but not for pressures greater than 18 mmHg. After the release of surface pressure, the reactive hyperemia peak of perfusion increased with heating. In Protocol III, where skin deformation (creep and relaxation) was measured during the application of 3.7 and 18 mmHg, heating caused the tissue to be stiffer, allowing less deformation. It was found that for surface pressures below 18 mmHg, increasing skin temperature significantly increased skin perfusion and tissue stiffness. The clinical significance of these findings may have relevance in evaluating temperature and pressure effects on skin blood flow and deformation as well as the efficacy of using temperature as a therapeutic modality in the treatment of pressure ulcers.

  20. Study of discharges produced by surface waves under medium and high pressure: application to chemical analysis

    International Nuclear Information System (INIS)

    Laye epouse Granier, Agnes

    1986-01-01

    This report deals with the study of microwave discharges produced in argon gas by surface waves in the 20-760 Torr pressure range. Application to chemical analysis by emission optical spectroscopy is also investigated. First of all we study the propagation of a surface wave in a bounded plasma in which the effective collision frequency for momentum transfer ν is higher than the excitation one. The axial electron density profile is determined from two diagnostic techniques, i.e., phase variations of the wave field and Stark broadening of H β line. Then we deduce the discharge characteristics ν, θ (maintaining power of an electron-ion pair) and E eff (effective electric field for discharge sustaining) from the electron density profile. Then an energy balance of the discharge is developed. It explains the change of operating conditions in the 20-50 Torr range. At low pressure the discharge is governed by ambipolar diffusion whereas at high pressure, the electrons are mainly lost by volume recombination of Ar 2 + . Finally, we report on chemical analysis experiment of gases (optimum sensibility in found near 100 Torr) and of metallic solutions sprayed by a graphite oven. Performances of such a design and ICP plasma torches are compared. (author) [fr

  1. Randomised, controlled trial of alternating pressure mattresses compared with alternating pressure overlays for the prevention of pressure ulcers: PRESSURE (pressure relieving support surfaces) trial.

    Science.gov (United States)

    Nixon, Jane; Cranny, Gillian; Iglesias, Cynthia; Nelson, E Andrea; Hawkins, Kim; Phillips, Angela; Torgerson, David; Mason, Su; Cullum, Nicky

    2006-06-17

    To compare whether differences exist between alternating pressure overlays and alternating pressure mattresses in the development of new pressure ulcers, healing of existing pressure ulcers, and patient acceptability. Pragmatic, open, multicentre, randomised controlled trial. 11 hospitals in six NHS trusts. 1972 people admitted to hospital as acute or elective patients. Participants were randomised to an alternating pressure mattress (n = 982) or an alternating pressure overlay (n = 990). The proportion of participants developing a new pressure ulcer of grade 2 or worse; time to development of new pressure ulcers; proportions of participants developing a new ulcer within 30 days; healing of existing pressure ulcers; and patient acceptability. Intention to treat analysis found no difference in the proportions of participants developing a new pressure ulcer of grade 2 or worse (10.7% overlay patients, 10.3% mattress patients; difference 0.4%, 95% confidence interval--2.3% to 3.1%, P = 0.75). More overlay patients requested change owing to dissatisfaction (23.3%) than mattress patients (18.9%, P = 0.02). No difference was found between alternating pressure mattresses and alternating pressure overlays in the proportion of people who develop a pressure ulcer. ISRCTN 78646179.

  2. Tactile surface classification for limbed robots using a pressure sensitive robot skin

    International Nuclear Information System (INIS)

    Shill, Jacob J; Collins Jr, Emmanuel G; Coyle, Eric; Clark, Jonathan

    2015-01-01

    This paper describes an approach to terrain identification based on pressure images generated through direct surface contact using a robot skin constructed around a high-resolution pressure sensing array. Terrain signatures for classification are formulated from the magnitude frequency responses of the pressure images. The initial experimental results for statically obtained images show that the approach yields classification accuracies >98%. The methodology is extended to accommodate the dynamic pressure images anticipated when a robot is walking or running. Experiments with a one-legged hopping robot yield similar identification accuracies ≈99%. In addition, the accuracies are independent with respect to changing robot dynamics (i.e., when using different leg gaits). The paper further shows that the high-resolution capabilities of the sensor enables similarly textured surfaces to be distinguished. A correcting filter is developed to accommodate for failures or faults that inevitably occur within the sensing array with continued use. Experimental results show using the correcting filter can extend the effective operational lifespan of a high-resolution sensing array over 6x in the presence of sensor damage. The results presented suggest this methodology can be extended to autonomous field robots, providing a robot with crucial information about the environment that can be used to aid stable and efficient mobility over rough and varying terrains. (paper)

  3. Green's functions potential fields on surfaces

    CERN Document Server

    Melnikov, Yuri A

    2017-01-01

    This book is comprehensive in its classical mathematical physics presentation, providing the reader with detailed instructions for obtaining Green's functions from scratch. Green's functions is an instrument easily accessible to practitioners who are engaged in design and exploitation of machines and structures in modern engineering practice. To date, there are no books available on the market that are devoted to the Green's function formalism for equations covered in this volume. The reader, with an undergraduate background in applied mathematics, can become an active user of the Green's function approach. For the first time, Green's functions are discussed for a specific class of problems dealing with potential fields induced in thin-wall structures and therefore, the reader will have first-hand access to a novel issue. This Work is accessible to researchers in applied mathematics, mechanics, and relevant disciplines such as engineering, as well as to upper level undergraduates and graduate students.

  4. Near 7-day response of ocean bottom pressure to atmospheric surface pressure and winds in the northern South China Sea

    Science.gov (United States)

    Zhang, Kun; Zhu, Xiao-Hua; Zhao, Ruixiang

    2018-02-01

    Ocean bottom pressures, observed by five pressure-recording inverted echo sounders (PIESs) from October 2012 to July 2014, exhibit strong near 7-day variability in the northern South China Sea (SCS) where long-term in situ bottom pressure observations are quite sparse. This variability was strongest in October 2013 during the near two years observation period. By joint analysis with European Center for Medium-Range Weather Forecasts (ECMWF) data, it is shown that the near 7-day ocean bottom pressure variability is closely related to the local atmospheric surface pressure and winds. Within a period band near 7 days, there are high coherences, exceeding 95% significance level, of observed ocean bottom pressure with local atmospheric surface pressure and with both zonal and meridional components of the wind. Ekman pumping/suction caused by the meridional component of the wind in particular, is suggested as one driving mechanism. A Kelvin wave response to the near 7-day oscillation would propagate down along the continental slope, observed at the Qui Nhon in the Vietnam. By multiple and partial coherence analyses, we find that local atmospheric surface pressure and Ekman pumping/suction show nearly equal influence on ocean bottom pressure variability at near 7-day periods. A schematic diagram representing an idealized model gives us a possible mechanism to explain the relationship between ocean bottom pressure and local atmospheric forcing at near 7-day periods in the northern SCS.

  5. Surface electric fields for North America during historical geomagnetic storms

    Science.gov (United States)

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  6. Surface Treatment of Polypropylene Films Using Dielectric Barrier Discharge with Magnetic Field

    International Nuclear Information System (INIS)

    Wang Changquan; Zhang Guixin; Wang Xinxin; Chen Zhiyu

    2012-01-01

    Atmospheric pressure non-thermal plasma is of interest for industrial applications. In this study, polypropylene (PP) films are modified by a dielectric barrier discharge (DBD) with a non-uniform magnetic field in air at atmospheric pressure. The surface properties of the PP films before and after a DBD treatment are studied by using contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The effect of treatment time on the surface modification with and without a magnetic field is investigated. It is found that the hydrophilic improvement depends on the treatment time and magnetic field. It is also found that surface roughness and oxygen-containing groups are introduced onto the PP film surface after the DBD treatment. Surface roughness and oxygen-containing polar functional groups of the PP films increase with the magnetic induction density. The functional groups are identified as C-O, C=O and O-C=O by using XPS analysis. It is concluded that the hydrophilic improvement of PP films treated with a magnetic field is due to a greater surface roughness and more oxygen-containing groups. (plasma technology)

  7. Pair-breaking effects by parallel magnetic field in electric-field-induced surface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Nabeta, Masahiro, E-mail: nabeta@mp.okayama-u.ac.jp; Tanaka, Kenta K.; Onari, Seiichiro; Ichioka, Masanori

    2016-11-15

    Highlights: • Zeeman effect shifts superconducting gaps of sub-band system, towards pair-breaking. • Higher-level sub-bands become normal-state-like electronic states by magnetic fields. • Magnetic field dependence of zero-energy DOS reflects multi-gap superconductivity. - Abstract: We study paramagnetic pair-breaking in electric-field-induced surface superconductivity, when magnetic field is applied parallel to the surface. The calculation is performed by Bogoliubov-de Gennes theory with s-wave pairing, including the screening effect of electric fields by the induced carriers near the surface. Due to the Zeeman shift by applied fields, electronic states at higher-level sub-bands become normal-state-like. Therefore, the magnetic field dependence of Fermi-energy density of states reflects the multi-gap structure in the surface superconductivity.

  8. Pair-breaking effects by parallel magnetic field in electric-field-induced surface superconductivity

    International Nuclear Information System (INIS)

    Nabeta, Masahiro; Tanaka, Kenta K.; Onari, Seiichiro; Ichioka, Masanori

    2016-01-01

    Highlights: • Zeeman effect shifts superconducting gaps of sub-band system, towards pair-breaking. • Higher-level sub-bands become normal-state-like electronic states by magnetic fields. • Magnetic field dependence of zero-energy DOS reflects multi-gap superconductivity. - Abstract: We study paramagnetic pair-breaking in electric-field-induced surface superconductivity, when magnetic field is applied parallel to the surface. The calculation is performed by Bogoliubov-de Gennes theory with s-wave pairing, including the screening effect of electric fields by the induced carriers near the surface. Due to the Zeeman shift by applied fields, electronic states at higher-level sub-bands become normal-state-like. Therefore, the magnetic field dependence of Fermi-energy density of states reflects the multi-gap structure in the surface superconductivity.

  9. Surface treatment of a titanium implant using low temperature atmospheric pressure plasmas

    Science.gov (United States)

    Lee, Hyun-Young; Tang, Tianyu; Ok, Jung-Woo; Kim, Dong-Hyun; Lee, Ho-Jun; Lee, Hae June

    2015-09-01

    During the last two decades, atmospheric pressure plasmas(APP) are widely used in diverse fields of biomedical applications, reduction of pollutants, and surface treatment of materials. Applications of APP to titanium surface of dental implants is steadily increasing as it renders surfaces wettability and modifies the oxide layer of titanium that hinders the interaction with cells and proteins. In this study, we have treated the titanium surfaces of screw-shaped implant samples using a plasma jet which is composed of a ceramic coaxial tube of dielectrics, a stainless steel inner electrode, and a coper tube outer electrode. The plasma ignition occurred with Ar gas flow between two coaxial metal electrodes and a sinusoidal bias voltage of 3 kV with a frequency of 20 kHz. Titanium materials used in this study are screw-shaped implants of which diameter and length are 5 mm and 13 mm, respectively. Samples were mounted at a distance of 5 mm below the plasma source, and the plasma treatment time was set to 3 min. The wettability of titanium surface was measured by the moving speed of water on its surface, which is enhanced by plasma treatment. The surface roughness was also measured by atomic force microscopy. The optimal condition for wettability change is discussed.

  10. Feedback Regulation of Intracellular Hydrostatic Pressure in Surface Cells of the Lens.

    Science.gov (United States)

    Gao, Junyuan; Sun, Xiurong; White, Thomas W; Delamere, Nicholas A; Mathias, Richard T

    2015-11-03

    In wild-type lenses from various species, an intracellular hydrostatic pressure gradient goes from ∼340 mmHg in central fiber cells to 0 mmHg in surface cells. This gradient drives a center-to-surface flow of intracellular fluid. In lenses in which gap-junction coupling is increased, the central pressure is lower, whereas if gap-junction coupling is reduced, the central pressure is higher but surface pressure is always zero. Recently, we found that surface cell pressure was elevated in PTEN null lenses. This suggested disruption of a feedback control system that normally maintained zero surface cell pressure. Our purpose in this study was to investigate and characterize this feedback control system. We measured intracellular hydrostatic pressures in mouse lenses using a microelectrode/manometer-based system. We found that all feedback went through transport by the Na/K ATPase, which adjusted surface cell osmolarity such that pressure was maintained at zero. We traced the regulation of Na/K ATPase activity back to either TRPV4, which sensed positive pressure and stimulated activity, or TRPV1, which sensed negative pressure and inhibited activity. The inhibitory effect of TRPV1 on Na/K pumps was shown to signal through activation of the PI3K/AKT axis. The stimulatory effect of TRPV4 was shown in previous studies to go through a different signal transduction path. Thus, there is a local two-legged feedback control system for pressure in lens surface cells. The surface pressure provides a pedestal on which the pressure gradient sits, so surface pressure determines the absolute value of pressure at each radial location. We speculate that the absolute value of intracellular pressure may set the radial gradient in the refractive index, which is essential for visual acuity. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  11. Pressure exerted by a vesicle on a surface

    International Nuclear Information System (INIS)

    Owczarek, A L; Prellberg, T

    2014-01-01

    Several recent works have considered the pressure exerted on a wall by a model polymer. We extend this consideration to vesicles attached to a wall, and hence include osmotic pressure. We do this by considering a two-dimensional directed model, namely that of area-weighted Dyck paths. Not surprisingly, the pressure exerted by the vesicle on the wall depends on the osmotic pressure inside, especially its sign. Here, we discuss the scaling of this pressure in the different regimes, paying particular attention to the crossover between positive and negative osmotic pressure. In our directed model, there exists an underlying Airy function scaling form, from which we extract the dependence of the bulk pressure on small osmotic pressures. (paper)

  12. Axially symmetric, stationary gravitational field equations and pseudospherical surfaces

    International Nuclear Information System (INIS)

    Tomimatsu, Akira.

    1981-04-01

    For axially symmetric, stationary gravitational field equations, a new Lax pair of the inverse scattering method is presented from a geometrical point of view. The metric coefficient e sup(2γ) (= -g sub(rho rho)g sub(tt)sup(-1)) is taken as the basic field variable, which satisfies an equation describing pseudospherical surfaces, i.e., surfaces of constant negative Gaussian curvature. The equations for other metric coefficients are also discussed. (author)

  13. Laser Anemometer Measurements of the Flow Field in a 4:1 Pressure Ratio Centrifugal Impeller

    Science.gov (United States)

    Skoch, G. J.; Prahst, P. S.; Wernet, M. P.; Wood, J. R.; Strazisar, A. J.

    1997-01-01

    A laser-doppler anemometer was used to obtain flow-field velocity measurements in a 4:1 pressure ratio, 4.54 kg/s (10 lbm/s), centrifugal impeller, with splitter blades and backsweep, which was configured with a vaneless diffuser. Measured through-flow velocities are reported for ten quasi-orthogonal survey planes at locations ranging from 1% to 99% of main blade chord. Measured through-flow velocities are compared to those predicted by a 3-D viscous steady flow analysis (Dawes) code. The measurements show the development and progression through the impeller and vaneless diffuser of a through-flow velocity deficit which results from the tip clearance flow and accumulation of low momentum fluid centrifuged from the blade and hub surfaces. Flow traces from the CFD analysis show the origin of this deficit which begins to grow in the inlet region of the impeller where it is first detected near the suction surface side of the passage. It then moves toward the pressure side of the channel, due to the movement of tip clearance flow across the impeller passage, where it is cut by the splitter blade leading edge. As blade loading increases toward the rear of the channel the deficit region is driven back toward the suction surface by the cross-passage pressure gradient. There is no evidence of a large wake region that might result from flow separation and the impeller efficiency is relatively high. The flow field in this impeller is quite similar to that documented previously by NASA Lewis in a large low-speed backswept impeller.

  14. Investigation of working pressure on the surface roughness controlling technology of glow discharge polymer films based on the diagnosed plasma

    Science.gov (United States)

    Zhang, Ling; Chen, Guo; He, Zhibing; Ai, Xing; Huang, Jinglin; Liu, Lei; Tang, Yongjian; He, Xiaoshan

    2017-07-01

    The effects of working pressure on the component, surface morphology, surface roughness, and deposition rate of glow discharge polymer (GDP) films by a trans-2-butene/hydrogen gas mixture were investigated based on plasma characteristics diagnosis. The composition and ion energy distributions of a multi-carbon (C4H8/H2) plasma mixture at different working pressures were diagnosed by an energy-resolved mass spectrometer (MS) during the GDP film deposition process. The Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (SEM) and white-light interferometer (WLI) results were obtained to investigate the structure, morphology and roughness characterization of the deposited films, respectively. It was found that the degree of ionization of the C4H8/H2 plasma reduces with an increase in the working pressure. At a low working pressure, the C-H fragments exhibited small-mass and high ion energy in plasma. In this case, the film had a low CH3/CH2 ratio, and displayed a smooth surface without any holes, cracks or asperities. While the working pressure increased to 15 Pa, the largest number of large-mass fragments led to the deposition rate reaching a maximum of 2.11 μm h-1, and to hole defects on the film surface. However, continuing to increase the working pressure, the film surface became smooth again, and the interface between clusters became inconspicuous without etching pits.

  15. Laboratory measurement of the interface pressures applied by active therapy support surfaces: a consensus document.

    Science.gov (United States)

    2010-02-01

    A key element in pressure ulcer prevention and management is the selection of appropriate pressure redistributing (PR) patient support surfaces for use while seated and in bed. However little explicit guidance exists allowing standardised quantitative comparison of different PR surfaces based upon their ability to redistribute pressure from anatomical landmarks such as the heels and sacrum. In 2008 a working group was established in Europe through the US National Pressure Ulcer Advisory Panel (NPUAP) support surface standardisation initiative (S3I) and under the aegis of the European Pressure Ulcer Advisory Panel with the specific remit of developing test methods for the evaluation of active therapy support surfaces (alternating pressure air mattresses). This report describes a consensus development process to agree test methods appropriate to compare active therapy surfaces based upon their ability to redistribute pressure from the sacrum and the heels. Copyright 2009 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

  16. Geosynchronous magnetic field responses to fast solar wind dynamic pressure enhancements: MHD field model

    Directory of Open Access Journals (Sweden)

    T. R. Sun

    2012-08-01

    Full Text Available We performed global MHD simulations of the geosynchronous magnetic field in response to fast solar wind dynamic pressure (Pd enhancements. Taking three Pd enhancement events in 2000 as examples, we found that the main features of the total field B and the dominant component Bz can be efficiently predicted by the MHD model. The predicted B and Bz varies with local time, with the highest level near noon and a slightly lower level around mid-night. However, it is more challenging to accurately predict the responses of the smaller component at the geosynchronous orbit (i.e., Bx and By. In contrast, the limitations of T01 model in predicting responses to fast Pd enhancements are presented.

  17. Reproduction of pressure field in ultrasonic-measurement-integrated simulation of blood flow.

    Science.gov (United States)

    Funamoto, Kenichi; Hayase, Toshiyuki

    2013-07-01

    Ultrasonic-measurement-integrated (UMI) simulation of blood flow is used to analyze the velocity and pressure fields by applying feedback signals of artificial body forces based on differences of Doppler velocities between ultrasonic measurement and numerical simulation. Previous studies have revealed that UMI simulation accurately reproduces the velocity field of a target blood flow, but that the reproducibility of the pressure field is not necessarily satisfactory. In the present study, the reproduction of the pressure field by UMI simulation was investigated. The effect of feedback on the pressure field was first examined by theoretical analysis, and a pressure compensation method was devised. When the divergence of the feedback force vector was not zero, it influenced the pressure field in the UMI simulation while improving the computational accuracy of the velocity field. Hence, the correct pressure was estimated by adding pressure compensation to remove the deteriorating effect of the feedback. A numerical experiment was conducted dealing with the reproduction of a synthetic three-dimensional steady flow in a thoracic aneurysm to validate results of the theoretical analysis and the proposed pressure compensation method. The ability of the UMI simulation to reproduce the pressure field deteriorated with a large feedback gain. However, by properly compensating the effects of the feedback signals on the pressure, the error in the pressure field was reduced, exhibiting improvement of the computational accuracy. It is thus concluded that the UMI simulation with pressure compensation allows for the reproduction of both velocity and pressure fields of blood flow. Copyright © 2012 John Wiley & Sons, Ltd.

  18. Pressure-induced switching in ferroelectrics: Phase-field modeling, electrochemistry, flexoelectric effect, and bulk vacancy dynamics

    Science.gov (United States)

    Cao, Ye; Morozovska, Anna; Kalinin, Sergei V.

    2017-11-01

    Pressure-induced polarization switching in ferroelectric thin films has emerged as a powerful method for domain patterning, allowing us to create predefined domain patterns on free surfaces and under thin conductive top electrodes. However, the mechanisms for pressure-induced polarization switching in ferroelectrics remain highly controversial, with flexoelectricity, polarization rotation and suppression, and bulk and surface electrochemical processes all being potentially relevant. Here we classify possible pressure-induced switching mechanisms, perform elementary estimates, and study in depth using phase-field modeling. We show that magnitudes of these effects are remarkably close and give rise to complex switching diagrams as a function of pressure and film thickness with nontrivial topology or switchable and nonswitchable regions.

  19. Variation of surface electric field during geomagnetic disturbed ...

    Indian Academy of Sciences (India)

    storm current generators, through the ionosphere, and down to the Earth's surface in the fair ... Atmospheric electric field; magnetic storm; magnetosphere; ionosphere; global electrical circuit. J. Earth Syst. Sci. 124, No. 8, December ... electrical conductivity of the ice surface is in sev- eral orders of magnitude higher than that ...

  20. Surface diagnostics of evaporating droplets of nanosphere suspension: Fano interference and surface pressure.

    Science.gov (United States)

    Kolwas, Maciej; Kolwas, Krystyna; Derkachov, Gennadiy; Jakubczyk, Daniel

    2015-03-14

    The evaporation of a single, levitating microdroplet of glycols containing SiO2 nanospheres, both of similar refraction indices, was studied by observing changes in the interference pattern and intensities of polarized and depolarized scattered laser light. The evolution of the effective radius of the droplet has been found on the basis of Mie scattering theory supplemented by the "electrical weighting" measurement of droplet mass evolution. During formation of a layer of nanospheres on the droplet surface, the asymmetric Fano profile was observed which was found to be due to the destructive and constructive interference of overlapping processes: (i) the scattering on single nanospheres emerging on the droplet surface and (ii) the scattering on ensembles of closely spaced (comparing to the light wavelength) nanospheres of an evolving surface film. Therefore we report the first observation of the Fano interference in the time domain rather than in the spectral domain. The optical surface diagnostics was complemented with the thermodynamics-like analysis in terms of the effective droplet surface pressure isotherm and with numerical simulations illustrating evaporation driven changes in the distribution of nanospheres. The reported study can serve as the basis for a wide range of novel diagnostic methods for studying configuration changes in complex systems of nano- and microparticles evolving at the sub-wavelength scale.

  1. Surface structure of quark stars with magnetic fields

    Indian Academy of Sciences (India)

    We investigate the impact of magnetic fields on the electron distribution of the electrosphere of quark stars. For moderately strong magnetic fields of ∼ 1013 G, quantization effects are generally weak due to the large number density of electrons at surface, but can nevertheless affect the photon emission properties of quark ...

  2. Quantum field theory on higher-genus Riemann surfaces, 2

    International Nuclear Information System (INIS)

    Kubo, Reijiro; Ojima, Shuichi.

    1990-08-01

    Quantum field theory for closed bosonic string systems is formulated on arbitrary higher-genus Riemann surfaces in global operator formalism. Canonical commutation relations between bosonic string field X μ and their conjugate momenta P ν are derived in the framework of conventional quantum field theory. Problems arising in quantizing bosonic systems are considered in detail. Applying the method exploited in the preceding paper we calculate Ward-Takahashi identities. (author)

  3. Electric field vector measurements in a surface ionization wave discharge

    International Nuclear Information System (INIS)

    Goldberg, Benjamin M; Adamovich, Igor V; Lempert, Walter R; Böhm, Patrick S; Czarnetzki, Uwe

    2015-01-01

    This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ∼100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns −1 . The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (∼100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ∼1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85–95 Td, consistent with dc breakdown field estimated from the Paschen

  4. Variability of surface temperature in agricultural fields of central California

    Science.gov (United States)

    Hatfield, J. L.; Millard, J. P.; Goettelman, R. C.

    1982-01-01

    In an attempt to evaluate the relationship between hand-held infrared thermometers and aircraft thermal scanners in near-level terrain and to quantify the variability of surface temperatures within individual fields, ground-based and aircraft thermal sensor measurements were made along a 50-km transect on 3 May 1979 and a 20-km transect on 7 August 1980. These comparisons were made on fields near Davis, California. Agreement was within 1 C for fields covered with vegetation and 3.6 C for bare, dry fields. The variability within fields was larger for bare, dry fields than for vegetatively covered fields. In 1980, with improvements in the collection of ground truth data, the agreement was within 1 C for a variety of fields.

  5. Surface pressure and aerodynamic loads determination of a transonic airfoil based on particle image velocimetry

    International Nuclear Information System (INIS)

    Ragni, D; Ashok, A; Van Oudheusden, B W; Scarano, F

    2009-01-01

    The present investigation assesses a procedure to extract the aerodynamic loads and pressure distribution on an airfoil in the transonic flow regime from particle image velocimetry (PIV) measurements. The wind tunnel model is a two-dimensional NACA-0012 airfoil, and the PIV velocity data are used to evaluate pressure fields, whereas lift and drag coefficients are inferred from the evaluation of momentum contour and wake integrals. The PIV-based results are compared to those derived from conventional loads determination procedures involving surface pressure transducers and a wake rake. The method applied in this investigation is an extension to the compressible flow regime of that considered by van Oudheusden et al (2006 Non-intrusive load characterization of an airfoil using PIV Exp. Fluids 40 988–92) at low speed conditions. The application of a high-speed imaging system allows the acquisition in relatively short time of a sufficient ensemble size to compute converged velocity statistics, further translated in turbulent fluctuations included in the pressure and loads calculation, notwithstanding their verified negligible influence in the computation. Measurements are performed at varying spatial resolution to optimize the loads determination in the wake region and around the airfoil, further allowing us to assess the influence of spatial resolution in the proposed procedure. Specific interest is given to the comparisons between the PIV-based method and the conventional procedures for determining the pressure coefficient on the surface, the drag and lift coefficients at different angles of attack. Results are presented for the experiments at a free-stream Mach number M = 0.6, with the angle of attack ranging from 0° to 8°

  6. 3D electric field calculation with surface charge method

    International Nuclear Information System (INIS)

    Yamada, S.

    1992-01-01

    This paper describes an outline and some examples of three dimensional electric field calculations with a computer code developed at NIRS. In the code, a surface charge method is adopted because of it's simplicity in the mesh establishing procedure. The charge density in a triangular mesh is assumed to distribute with a linear function of the position. The electric field distribution is calculated for a pair of drift tubes with the focusing fingers on the opposing surfaces. The field distribution in an acceleration gap is analyzed with a Fourier-Bessel series expansion method. The calculated results excellently reproduces the measured data with a magnetic model. (author)

  7. Measurement of temperature and pressure on the surface of a blunt cone using FBG sensor in hypersonic wind tunnel

    International Nuclear Information System (INIS)

    Guru Prasad, A S; Sharath, U; Asokan, S; Nagarjun, V; Hegde, G M

    2013-01-01

    Measurement of temperature and pressure exerted on the leeward surface of a blunt cone specimen has been demonstrated in the present work in a hypersonic wind tunnel using fiber Bragg grating (FBG) sensors. The experiments were conducted on a 30° apex-angle blunt cone with 51 mm base diameter at wind flow speeds of Mach 6.5 and 8.35 in a 300 mm hypersonic wind tunnel of Indian Institute of Science, Bangalore. A special pressure insensitive temperature sensor probe along with the conventional bare FBG sensors was used for explicit temperature and aerodynamic pressure measurement respectively on the leeward surface of the specimen. computational fluid dynamics (CFD) simulation of the flow field around the blunt cone specimen has also been carried out to obtain the temperature and pressure at conditions analogous to experiments. The results obtained from FBG sensors and the CFD simulations are found to be in good agreement with each other. (paper)

  8. Tropical Pacific sea-surface temperatures and preceding sea level pressure anomalies in the subtropical North Pacific

    Science.gov (United States)

    Anderson, Bruce T.

    2003-12-01

    The correspondence of sea-surface temperature (SST) anomalies to changes in antecedent large-scale sea level pressure anomalies is investigated using reanalysis data. By statistically examining linearly coupled precursor sea level pressure fields and subsequent SST fields for different lag periods, it is possible to isolate a precursor mode of sea level pressure (SLP) variability in the central subtropical North Pacific that precedes variations in the January-March El Niño/Southern Oscillation (ENSO) by approximately 12-15 months. A sea level pressure index, which captures the important characteristics of this precursor mode of variability, is developed and evaluated. It is shown that both analyzed and observed versions of the index are significantly correlated with the January-March ENSO one year later. The SLP index is then used to examine the evolution of the surface circulation and temperature structures leading up to mature ENSO events. Initially, the January-March subtropical North Pacific SLP anomalies are associated with changes in the intensity of the subtropical trade wind regime over the North Pacific, as well as with SST anomalies over the eastern equatorial Pacific and subtropical central Pacific. In agreement with the correlation statistics associated with the SLP and lagged NINO3.4 indices, both the sea level pressure field and the SST field subsequently develop ENSO-like structures over the course of the following year. Significant discussion of these results and pertinent areas of future research are provided within the broader context of the ENSO system.

  9. Plasmas fluxes to surfaces for an oblique magnetic field

    International Nuclear Information System (INIS)

    Pitcher, C.S.; Stangeby, P.C.; Elder, J.D.; Bell, M.G.; Kilpatrick, S.J.; Manos, D.M.; Medley, S.S.; Owens, D.K.; Ramsey, A.T.; Ulrickson, M.

    1992-07-01

    The poloidal and toroidal spatial distributions of D α , He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface. The distributions are found not to agree with a model (the ''Cosine'' model) which determines the incident flux density using only the parallel fluxes in the scrape-off layer and the projected area of the surface perpendicular to the field lines. In particular, the Cosine model is not able to explain the significant fluxes observed at locations on the surface which are oblique to the magnetic field. It is further shown that these fluxes cannot be explained by the finite Larmor radius of impinging ions. Finally, it is demonstrated, with the use of Monte Carlo codes, that the distributions can be explained by including both parallel and cross-field transport onto the limiter surface

  10. Error Propagation dynamics: from PIV-based pressure reconstruction to vorticity field calculation

    Science.gov (United States)

    Pan, Zhao; Whitehead, Jared; Richards, Geordie; Truscott, Tadd; USU Team; BYU Team

    2017-11-01

    Noninvasive data from velocimetry experiments (e.g., PIV) have been used to calculate vorticity and pressure fields. However, the noise, error, or uncertainties in the PIV measurements would eventually propagate to the calculated pressure or vorticity field through reconstruction schemes. Despite the vast applications of pressure and/or vorticity field calculated from PIV measurements, studies on the error propagation from the velocity field to the reconstructed fields (PIV-pressure and PIV-vorticity are few. In the current study, we break down the inherent connections between PIV-based pressure reconstruction and PIV-based vorticity calculation. The similar error propagation dynamics, which involve competition between physical properties of the flow and numerical errors from reconstruction schemes, are found in both PIV-pressure and PIV-vorticity reconstructions.

  11. ALOAD - a code to determine the concentrated forces equivalent with a distributed pressure field for a FEM analysis

    Directory of Open Access Journals (Sweden)

    Nicolae APOSTOLESCU

    2010-12-01

    Full Text Available The main objective of this paper is to describe a code for calculating an equivalent systemof concentrate loads for a FEM analysis. The tables from the Aerodynamic Department containpressure field for a whole bearing surface, and integrated quantities both for the whole surface andfor fixed and mobile part. Usually in a FEM analysis the external loads as concentrated loadsequivalent to the distributed pressure field are introduced. These concentrated forces can also be usedin static tests. Commercial codes provide solutions for this problem, but what we intend to develop isa code adapted to the user’s specific needs.

  12. Preventing pressure ulcers--Are pressure-redistributing support surfaces effective? A Cochrane systematic review and meta-analysis.

    Science.gov (United States)

    McInnes, Elizabeth; Jammali-Blasi, Asmara; Bell-Syer, Sally; Dumville, Jo; Cullum, Nicky

    2012-03-01

    To undertake a systematic review of the effectiveness of pressure redistributing support surfaces in the prevention of pressure ulcers. Systematic review and meta-analysis. Cochrane Wound Group Specialised Register, The Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL. The reference sections of included trials were searched for further trials. Randomised controlled trials and quasi-randomised trials, published or unpublished, which assessed the effects of support surfaces in preventing pressure ulcers (of any grade), in any patient group, in any setting compared to any other support surface, were sought. Two reviewers extracted and summarised details of eligible trials using a standardised form and assessed the methodological quality of each trial using the Cochrane risk of bias tool. Fifty-three eligible trials were identified with a total of 16,285 study participants. Overall the risk of bias in the included trials was high. Pooled analysis showed that: (i) foam alternatives to the standard hospital foam mattress reduce the incidence of pressure ulcers in people at risk (RR 0.40, 95% CI 0.21-0.74) and Australian standard medical sheepskins prevent pressure ulcers compared to standard care (RR 0.48, 95% CI 0.31-0.74). Pressure-redistributing overlays on the operating table compared to standard care reduce postoperative pressure ulcer incidence (RR 0.53, 95% CI 0.33-0.85). While there is good evidence that higher specification foam mattresses, sheepskins, and that some overlays in the operative setting are effective in preventing pressure ulcers, there is insufficient evidence to draw conclusions on the value of seat cushions, limb protectors and various constant low pressure devices. The relative merits of higher-tech constant low pressure and alternating pressure for prevention are unclear. More robust trials are required to address these research gaps. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    Energy Technology Data Exchange (ETDEWEB)

    Abuzairi, Tomy [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electrical Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424 (Indonesia); Okada, Mitsuru [Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Nagatsu, Masaaki, E-mail: nagatsu.masaaki@shizuoka.ac.jp [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan)

    2016-12-30

    Highlights: • Spatio-temporal behaviors of capillary APPJs are studied for various substrates. • Plasma irradiation area depended on the substrate conductivity and permittivity. • Surface irradiation area was significantly broadened in polymer-like substrate. • Effect of applying a substrate bias on the APPJ irradiation area was investigated. - Abstract: An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5–4.2 km/s and 2–7 × 10{sup 17} m{sup −3}. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from −900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  14. On Discrete Killing Vector Fields and Patterns on Surfaces

    KAUST Repository

    Ben-Chen, Mirela

    2010-09-21

    Symmetry is one of the most important properties of a shape, unifying form and function. It encodes semantic information on one hand, and affects the shape\\'s aesthetic value on the other. Symmetry comes in many flavors, amongst the most interesting being intrinsic symmetry, which is defined only in terms of the intrinsic geometry of the shape. Continuous intrinsic symmetries can be represented using infinitesimal rigid transformations, which are given as tangent vector fields on the surface - known as Killing Vector Fields. As exact symmetries are quite rare, especially when considering noisy sampled surfaces, we propose a method for relaxing the exact symmetry constraint to allow for approximate symmetries and approximate Killing Vector Fields, and show how to discretize these concepts for generating such vector fields on a triangulated mesh. We discuss the properties of approximate Killing Vector Fields, and propose an application to utilize them for texture and geometry synthesis. Journal compilation © 2010 The Eurographics Association and Blackwell Publishing Ltd.

  15. Surface Tension of Organic Liquids Using the OPLS/AA Force Field.

    Science.gov (United States)

    Zubillaga, Rafael A; Labastida, Ariana; Cruz, Bibiana; Martínez, Juan Carlos; Sánchez, Enrique; Alejandre, José

    2013-03-12

    Molecular dynamics simulations are performed to obtain the surface tension of 61 organic liquids using the OPLS/AA (all-atom optimized potential for liquid simulations). The force field parameters are the same as those recently used (Caleman et al. J. Chem. Theory Comput.2012, 8, 61) to determine several thermodynamic properties of 146 organic liquids. The correct evaluation of surface tension using slab simulations of liquids requires one to properly take into account the long-range interactions (Trukhymchuk and Alejandre J. Chem. Phys.1999, 111, 8510). In addition, the liquid density from slab simulations has to be the same as that obtained in liquid simulations at constant temperature and pressure. The new results of surface tensions from this work improve those reported by Caleman et al. The OPLS/AA force field gives good surface tensions compared with experimental data for most of the systems studied in this work, although it was developed to simulate liquids.

  16. Radiation pressure and the linear momentum of the electromagnetic field

    OpenAIRE

    Mansuripur, Masud

    2013-01-01

    We derive the force of the electromagnetic radiation on material objects by a direct application of the Lorentz law of classical electro-dynamics. The derivation is straightforward in the case of solid metals and solid dielectrics, where the mass density and the optical constants of the media are assumed to remain unchanged under internal and external pressures, and where material flow and deformation can be ignored. For metallic mirrors, we separate the contribution to the radiation pressure...

  17. Perception of surface pressure applied to the hand.

    Science.gov (United States)

    Johansson, L; Kjellberg, A; Kilbom, A; Hägg, G M

    1999-10-01

    The study aimed to determine the relationship between the physical magnitude and the subjective perception of applied pressure, and to determine discomfort and pain thresholds. Free modulus magnitude estimation of the subjective pressure level was made on three points: on the finger, the palm and the thenar area. The pressure was judged to be higher at the thenar point than at the finger and palm points. The slopes of the linear functions (log magnitude estimates as a function of log pressure) were 0.66, 0.78 and 0.76 for the finger, palm and thenar points respectively. The discomfort threshold was 38% of the pain pressure threshold at the finger point, 40% at the palm and 22% at the thenar point. The results are probably of importance in the performance of hand-intensive work, in particular in the design of hand tools.

  18. Hydrophilic film polymerized on the inner surface of PMMA tube by an atmospheric pressure plasma jet

    Science.gov (United States)

    Yin, Mengmeng; Huang, Jun; Yu, Jinsong; Chen, Guangliang; Qu, Shanqing

    2017-07-01

    Polymethyl methacrylate (PMMA) tube is widely used in biomedical and mechanical engineering fields. However, it is hampered for some special applications as the inner surface of PMMA tube exhibts a hydrophobic characteristic. The aim of this work is to explore the hydrophilic modification of the inner surface of the PMMA tubes using an atmospheric pressure plasma jet (APPJ) system that incorporates the acylic acid monomer (AA). Polar groups were grafted onto the inner surface of PMMA tube via the reactive radicals (•OH, •H, •O) generated in the Ar/O2/AA plasma, which were observed by the optical emission spectroscopy (OES). The deposition of the PAA thin layer on the PMMA surface was verified through the ATR-FTIR spectra, which clearly showed the strengthened stretching vibration of the carbonyl group (C=O) at 1700 cm-1. The XPS data show that the carbon ratios of C-OH/R and COOH/R groups increased from 9.50% and 0.07% to 13.49% and 17.07% respectively when a discharge power of 50 W was used in the APPJ system. As a result, the static water contat angle (WCA) of the modified inner surface of PMMA tube decreased from 100° to 48°. Furthermore, the biocompatibility of the APP modified PMMA tubes was illustrated by the study of the adhesion of the cultured MC3T3-E1 osteocyte cells, which exhibted a significantly enhanced adhesion density.

  19. Study of the magnetic superconductor, Y9Co7, at high pressure and high magnetic field

    International Nuclear Information System (INIS)

    Huang, C.Y.; Olsen, C.E.; Fuller, W.W.; Huang, J.H.; Wolf, S.A.

    1983-01-01

    The electrical resistance and magnetic susceptibility of the magnetic superconductor, Y 9 Co 7 has been measured at pressures up to 20 kbar and in magnetic fields up to 6T. It has been found that pressure suppresses the magnetism resulting in a higher superconducting transition temperature and conclude that Y 9 Co 7 is an itinerant ferromagnet, not a spin-glass. Pressure also sharpens the superconducting transition and increases the critical magnetic field, signifying that the long range ferromagnetic and superconducting order parameters co-exist but vary spatially. For pressures greater than 6 kbar, the magnetoresistance is always positive, further indicating the suppression of magnetism by high pressure. (author)

  20. Propeller Cavitation in Non-Uniform Flow and Correlation with the Near Pressure Field

    Directory of Open Access Journals (Sweden)

    Francisco Alves Pereira

    2016-11-01

    Full Text Available An experimental study is carried out in a cavitation tunnel on a propeller operating downstream of a non-uniform wake. The goal of this work is to establish quantitative correlations between the near pressure field and the cavitation pattern that takes place on the propeller blades. The pressure field is measured at the walls of the test section and in the near wake of the propeller and is combined with quantitative high-speed image recording of the cavitation pattern. Through harmonic analysis of the pressure data and image processing techniques that allow retrieving the cavitation extension and volume, we discuss the potential sources that generate the pressure fluctuations. Time correlations are unambiguously established between pressure peak fluctuations and cavitation collapse events, based on the Rayleigh collapse time. Finally, we design a model to predict the cavitation-induced pressure fluctuations from the derivation of the cavitation volume acceleration. A remarkable agreement is observed with the actual pressure field.

  1. Pressure effects of the magnetic structures of TbNi2Si2 in external fields

    International Nuclear Information System (INIS)

    Kawano, S.; Fukui, S.; Onodera, A.; Amita, F.; Katano, S.

    1997-01-01

    Single crystal neutron diffraction studies of the field-induced magnetic structures of TbNi 2 Si 2 have been performed at 1.7 K without pressure and under 0.7 GPa using a cryomagnetic high pressure system. Without pressure at 1.7 K four intermediate structures have been identified between a zero-field simple antiferromagnetic structure and a fully ferromagnetic one. Under 0.7 GPa two field-induced phases with an antiphase-type modulation along the left angle 110 right angle direction was newly observed above 4 T, while below 3.3 T zero pressure structures are still retained. (orig.)

  2. Understanding the Hydromechanical Behavior of a Fault Zone From Transient Surface Tilt and Fluid Pressure Observations at Hourly Time Scales

    Science.gov (United States)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Burbey, Thomas J.; Boudin, Frédérick; Lavenant, Nicolas; Davy, Philippe

    2017-12-01

    Flow through reservoirs such as fractured media is powered by head gradients which also generate measurable poroelastic deformation of the rock body. The combined analysis of surface deformation and subsurface pressure provides valuable insights of a reservoir's structure and hydromechanical properties, which are of interest for deep-seated CO2 or nuclear waste storage for instance. Among all surveying tools, surface tiltmeters offer the possibility to grasp hydraulically induced deformations over a broad range of time scales with a remarkable precision. Here we investigate the information content of transient surface tilt generated by the pressurization a kilometer scale subvertical fault zone. Our approach involves the combination of field data and results of a fully coupled poromechanical model. The signature of pressure changes in the fault zone due to pumping cycles is clearly recognizable in field tilt data and we aim to explain the peculiar features that appear in (1) tilt time series alone from a set of four instruments and 2) the ratio of tilt over pressure. We evidence that the shape of tilt measurements on both sides of a fault zone is sensitive to its diffusivity and its elastic modulus. The ratio of tilt over pressure predominantly encompasses information about the system's dynamic behavior and extent of the fault zone and allows separating contributions of flow in the different compartments. Hence, tiltmeters are well suited to characterize hydromechanical processes associated with fault zone hydrogeology at short time scales, where spaceborne surveying methods fail to recognize any deformation signal.

  3. Pressure-dependent surface viscosity and its surprising consequences in interfacial lubrication flows

    Science.gov (United States)

    Manikantan, Harishankar; Squires, Todd M.

    2017-02-01

    The surface shear rheology of many insoluble surfactants depends strongly on the surface pressure (or concentration) of that surfactant. Here we highlight the dramatic consequences that surface-pressure-dependent surface viscosities have on interfacially dominant flows, by considering lubrication-style geometries within high Boussinesq (Bo) number flows. As with three-dimensional lubrication, high-Bo surfactant flows through thin gaps give high surface pressures, which in turn increase the local surface viscosity, further amplifying lubrication stresses and surface pressures. Despite their strong nonlinearity, the governing equations are separable, so that results from two-dimensional Newtonian lubrication analyses may be immediately adapted to treat surfactant monolayers with a general functional form of ηs(Π ) . Three paradigmatic systems are analyzed to reveal qualitatively new features: a maximum, self-limiting value for surfactant fluxes and particle migration velocities appears for Π -thickening surfactants, and kinematic reversibility is broken for the journal bearing and for suspensions more generally.

  4. Acoustic propagation operators for pressure waves on an arbitrarily curved surface in a homogeneous medium

    Science.gov (United States)

    Sun, Yimin; Verschuur, Eric; van Borselen, Roald

    2018-03-01

    The Rayleigh integral solution of the acoustic Helmholtz equation in a homogeneous medium can only be applied when the integral surface is a planar surface, while in reality almost all surfaces where pressure waves are measured exhibit some curvature. In this paper we derive a theoretically rigorous way of building propagation operators for pressure waves on an arbitrarily curved surface. Our theory is still based upon the Rayleigh integral, but it resorts to matrix inversion to overcome the limitations faced by the Rayleigh integral. Three examples are used to demonstrate the correctness of our theory - propagation of pressure waves acquired on an arbitrarily curved surface to a planar surface, on an arbitrarily curved surface to another arbitrarily curved surface, and on a spherical cap to a planar surface, and results agree well with the analytical solutions. The generalization of our method for particle velocities and the calculation cost of our method are also discussed.

  5. Prevention and management of pressure ulcers: support surfaces.

    Science.gov (United States)

    Moore, Zena; Stephen Haynes, Jackie; Callaghan, Rosie

    Pressure ulcers are a common and debilitating problem in health care, impacting negatively on health-related quality of life and compounding challenges in achieving patient safety targets. Pressure ulcer prevention is a multidisciplinary team effort, involving a myriad of interventions, such as nutrition, skin care and repositioning. This article discusses the factors influencing pressure ulcer development, and then elaborates on the principles of prevention. This is followed by a focused discussion on the use of redistribution devices and the importance of the cover of such equipment in contributing to achieving good standards in prevention.

  6. Pressure loss reduction in hydrogen pipelines by surface restructuring

    Energy Technology Data Exchange (ETDEWEB)

    Peet, Y.; Sagaut, P. [Insitut Jean Le Rond d' Alembert, UMR CNRS 7190, Universite Pierre et Marie Curie - Paris 6, 4 place Jussieu - case 162, F-75252 Paris Cedex 5 (France); Charron, Y. [IFP- Institut Francais du Petrole, Rueil Malmaison Cedex, 92852 (France)

    2009-11-15

    This paper concerns the reduction of pressure losses during pipeline hydrogen transportation, as the cost of hydrogen compression is a significant obstacle for efficient hydrogen pumping on a large-scale basis. The use of organized micro-structures on pipeline walls is proposed to obtain lower values of pressure losses with respect to smooth walls. Three-dimensional micro-structures of a sinusoidal shape are investigated as potentially more efficient counterparts to conventional two-dimensional structures (riblets) developed in aerospace industry. Aerodynamic performance of three-dimensional structures is investigated computationally in terms of both skin friction and pressure drag, two constituents of the total drag. Three-dimensional structures are shown to provide larger total drag reduction than two-dimensional structures for some range of geometrical parameters (14.5% versus 11%). Parametric dependence of both pressure and skin friction drag on structure geometry is analyzed, and an optimum configuration maximizing the total drag reduction is proposed. (author)

  7. 3D pressure field in lipid membranes and membrane-protein complexes

    DEFF Research Database (Denmark)

    Ollila, O H Samuli; Risselada, H Jelger; Louhivuori, Martti

    2009-01-01

    We calculate full 3D pressure fields for inhomogeneous nanoscale systems using molecular dynamics simulation data. The fields represent systems with increasing level of complexity, ranging from semivesicles and vesicles to membranes characterized by coexistence of two phases, including also...... a protein-membrane complex. We show that the 3D pressure field is distinctly different for curved and planar bilayers, the pressure field depends strongly on the phase of the membrane, and that an integral protein modulates the tension and elastic properties of the membrane....

  8. field performance of cowpea genotypes grown under virus pressure ...

    African Journals Online (AJOL)

    journal

    viral diseases, particularly Cucumber mosaic virus (CMV) and Blackeye cowpea mosaic virus (BlCMV), can be a limiting factor in cowpea production. We evaluated under virus pressure the performance of four PI's (441917,. 441919, 612607, 180014) and a commercial cultivar (Coronet), in Puerto Rico during 2007-2008.

  9. field performance of cowpea genotypes grown under virus pressure ...

    African Journals Online (AJOL)

    journal

    Cowpea [Vigna unguiculata (L.) Walp] is an important grain legume in many regions of the tropics. However, viral diseases, particularly Cucumber mosaic virus (CMV) and Blackeye cowpea mosaic virus (BlCMV), can be a limiting factor in cowpea production. We evaluated under virus pressure the performance of four PI's ...

  10. Contribution of surface analysis spectroscopic methods to the lubrication field

    International Nuclear Information System (INIS)

    Blanc, C.

    1979-01-01

    The analytical surface technics such as ESCA, AES and SIMS are tested to be applied to a particular lubrication field. One deals with a 100 C 6 steel surface innumered in tricresylphosphate at 110 0 C for 15 days. The nature of the first layers is studied after relevant solvant cleaning. An iron oxide layer is produced on the bearing surface, namely αFe 2 -O 3 . ESCA, AES and SIMS studies show an overlayer of iron phosphate. The exact nature of iron phosphate is not clearly established but the formation of a ferrous phosphate coating can be assumed from ESCA analysis [fr

  11. Support surfaces for pressure ulcer prevention: A network meta-analysis.

    Science.gov (United States)

    Shi, Chunhu; Dumville, Jo C; Cullum, Nicky

    2018-01-01

    Pressure ulcers are a prevalent and global issue and support surfaces are widely used for preventing ulceration. However, the diversity of available support surfaces and the lack of direct comparisons in RCTs make decision-making difficult. To determine, using network meta-analysis, the relative effects of different support surfaces in reducing pressure ulcer incidence and comfort and to rank these support surfaces in order of their effectiveness. We conducted a systematic review, using a literature search up to November 2016, to identify randomised trials comparing support surfaces for pressure ulcer prevention. Two reviewers independently performed study selection, risk of bias assessment and data extraction. We grouped the support surfaces according to their characteristics and formed evidence networks using these groups. We used network meta-analysis to estimate the relative effects and effectiveness ranking of the groups for the outcomes of pressure ulcer incidence and participant comfort. GRADE was used to assess the certainty of evidence. We included 65 studies in the review. The network for assessing pressure ulcer incidence comprised evidence of low or very low certainty for most network contrasts. There was moderate-certainty evidence that powered active air surfaces and powered hybrid air surfaces probably reduce pressure ulcer incidence compared with standard hospital surfaces (risk ratios (RR) 0.42, 95% confidence intervals (CI) 0.29 to 0.63; 0.22, 0.07 to 0.66, respectively). The network for comfort suggested that powered active air-surfaces are probably slightly less comfortable than standard hospital mattresses (RR 0.80, 95% CI 0.69 to 0.94; moderate-certainty evidence). This is the first network meta-analysis of the effects of support surfaces for pressure ulcer prevention. Powered active air-surfaces probably reduce pressure ulcer incidence, but are probably less comfortable than standard hospital surfaces. Most prevention evidence was of low or

  12. Surface-initiated phase transition in solid hydrogen under the high-pressure compression

    Science.gov (United States)

    Lei, Haile; Lin, Wei; Wang, Kai; Li, Xibo

    2018-03-01

    The large-scale molecular dynamics simulations have been performed to understand the microscopic mechanism governing the phase transition of solid hydrogen under the high-pressure compression. These results demonstrate that the face-centered-cubic-to-hexagonal close-packed phase transition is initiated first at the surfaces at a much lower pressure than in the volume and then extends gradually from the surface to volume in the solid hydrogen. The infrared spectra from the surface are revealed to exhibit a different pressure-dependent feature from those of the volume during the high-pressure compression. It is thus deduced that the weakening intramolecular H-H bonds are always accompanied by hardening surface phonons through strengthening the intermolecular H2-H2 coupling at the surfaces with respect to the counterparts in the volume at high pressures. This is just opposite to the conventional atomic crystals, in which the surface phonons are softening. The high-pressure compression has further been predicted to force the atoms or molecules to spray out of surface to degrade the pressure. These results provide a glimpse of structural properties of solid hydrogen at the early stage during the high-pressure compression.

  13. A field performance evaluation of drip emitters: pressure versus ...

    African Journals Online (AJOL)

    A comprehensive field evaluation of irrigation systems involves determining the overall efficiency of the system, for example, determining water use efficiency, field operating efficiency and water management practices in use. However, the objective of this study was to evaluate the operating pressure–discharge relationship ...

  14. A field performance evaluation of drip emitters: pressure versus ...

    African Journals Online (AJOL)

    Field evaluation of irrigation systems (drip) can form a basis for decision making as to whether the irrigation system needs rehabilitation, overhaul or even dismantling if found to be very uneconomical. A comprehensive field evaluation of irrigation systems involves determining the overall efficiency of the system, for example, ...

  15. Mechanoreceptor afferent activity compared with receptor field dimensions and pressure changes in feline urinary bladder.

    Science.gov (United States)

    Downie, J W; Armour, J A

    1992-11-01

    The relationship between vesical mechanoreceptor field dimensions and afferent nerve activity recorded in pelvic plexus nerve filaments was examined in chloralose-anesthetized cats. Orthogonal receptor field dimensions were monitored with piezoelectric ultrasonic crystals. Reflexly generated bladder contractile activity made measurements difficult, therefore data were collected from cats subjected to actual sacral rhizotomy. Afferent activity was episodic and was initiated at different pressure and receptor field dimension thresholds. Maximum afferent activity did not correlate with maximum volume or pressure. Furthermore, activity was not linearly related to intravesical pressure, receptor field dimensions, or calculated wall tension. Pressure-length hysteresis of the receptor fields occurred. The responses of identified afferent units and their associated receptor field dimensions to brief contractions elicited by the ganglion stimulant 1,1-dimethyl-4-phenylpiperazinium iodide (2.5-20 micrograms i.a.), studied under constant volume or constant pressure conditions, are compatible with bladder mechanoreceptors behaving as tension receptors. Because activity generated by bladder mechanoreceptors did not correlate in a simple fashion with intravesical pressure or receptor field dimensions, it is concluded that such receptors are influenced by the viscoelastic properties of the bladder wall. Furthermore, as a result of the heterogeneity of the bladder wall, receptor field tension appears to offer a more precise relationship with the activity of bladder wall mechanoreceptors than does intravesical pressure.

  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. Surface Pressure Dependencies in the GEOS-Chem-Adjoint System and the Impact of the GEOS-5 Surface Pressure on CO2 Model Forecast

    Science.gov (United States)

    Lee, Meemong; Weidner, Richard

    2016-01-01

    In the GEOS-Chem Adjoint (GCA) system, the total (wet) surface pressure of the GEOS meteorology is employed as dry surface pressure, ignoring the presence of water vapor. The Jet Propulsion Laboratory (JPL) Carbon Monitoring System (CMS) research team has been evaluating the impact of the above discrepancy on the CO2 model forecast and the CO2 flux inversion. The JPL CMS research utilizes a multi-mission assimilation framework developed by the Multi-Mission Observation Operator (M2O2) research team at JPL extending the GCA system. The GCA-M2O2 framework facilitates mission-generic 3D and 4D-variational assimilations streamlining the interfaces to the satellite data products and prior emission inventories. The GCA-M2O2 framework currently integrates the GCA system version 35h and provides a dry surface pressure setup to allow the CO2 model forecast to be performed with the GEOS-5 surface pressure directly or after converting it to dry surface pressure.

  18. Surface field in an ensemble of superconducting spheres under external magnetic field

    CERN Document Server

    Peñaranda, A; Ramírez-Piscina, L

    1999-01-01

    We perform calculations of the magnetic field on the surface of an ensemble of superconducting spheres when placed into an external magnetic field, which is the configuration employed in superheated superconducting granule detectors. The Laplace equation is numerically solved with appropriate boundary conditions by means of an iterative procedure and a multipole expansion.

  19. Atmospheric-pressure plasma activation and surface characterization on polyethylene membrane separator

    Science.gov (United States)

    Tseng, Yu-Chien; Li, Hsiao-Ling; Huang, Chun

    2017-01-01

    The surface hydrophilic activation of a polyethylene membrane separator was achieved using an atmospheric-pressure plasma jet. The surface of the atmospheric-pressure-plasma-treated membrane separator was found to be highly hydrophilic realized by adjusting the plasma power input. The variations in membrane separator chemical structure were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Chemical analysis showed newly formed carbonyl-containing groups and high surface concentrations of oxygen-containing species on the atmospheric-pressure-plasma-treated polymeric separator surface. It also showed that surface hydrophilicity primarily increased from the polar component after atmospheric-pressure plasma treatment. The surface and pore structures of the polyethylene membrane separator were examined by scanning electron microscopy, revealing a slight alteration in the pore structure. As a result of the incorporation of polar functionalities by atmospheric-pressure plasma activation, the electrolyte uptake and electrochemical impedance of the atmospheric-pressure-plasma-treated membrane separator improved. The investigational results show that the separator surface can be controlled by atmospheric-pressure plasma surface treatment to tailor the hydrophilicity and enhance the electrochemical performance of lithium ion batteries.

  20. Core surface magnetic field evolution 2000–2010

    DEFF Research Database (Denmark)

    Finlay, Chris; Jackson, A.; Gillet, N.

    2012-01-01

    We present new dedicated core surface field models spanning the decade from 2000.0 to 2010.0. These models, called gufm‐sat, are based on CHAMP, Ørsted and SAC‐C satellite observations along with annual differences of processed observatory monthly means. A spatial parametrization of spherical...... field and the unrealistic rapid decay typical of quadratic regularization at degrees above 12. We describe in detail aspects of the models that are relevant to core dynamics. Secular variation and secular acceleration are found to be of lower amplitude under the Pacific hemisphere where the core field...... is weaker. Rapid field evolution is observed under the eastern Indian Ocean associated with the growth and drift of an intense low latitude flux patch. We also find that the present axial dipole decay arises from a combination of subtle changes in the southern hemisphere field morphology....

  1. Surface structure of quark stars with magnetic fields

    Indian Academy of Sciences (India)

    the formation of quark stars, with particular attention to the attractive quark-nova scenario which may be connected to r-process nucleosynthesis. 2. Degenerate electron gas in a strong magnetic field. Recently, a few authors [21] pointed out that the deficit of (massive) strange quarks due to surface effects on the star can lead ...

  2. Field evidences of secondary surface ruptures occurred during the ...

    Indian Academy of Sciences (India)

    Surface rupture and source fault of the 20 February 1956 Eskişehir earthquake have been a matter of debate that potentially contributes towards the understanding of the active deformation and seismic risk in the highly populated NW Anatolia. Field observations on the two fault segments (namely Kavacık and Uludere ...

  3. Unsteady Surface Pressure Measurements on a Pitching Airfoil

    Science.gov (United States)

    1985-03-12

    through 8 Dynamics 7512B amplifiers. The pitching motions of the airfoil were generated by 6°jN\\! 920O/_ a PDP 11/03 computer controlling a Control...acquisition system. The pressure data were used to calculate pressure 2 coefficients which were in turn integrated to compute lift coefficients. Both...Airfoils," AIAA J., Vol. 13, No. 1, 17. Gormont, R.E., "A Mathenatical Model pp 71-79, Jan 1975. of Unsteady Aerodynamics and Radial 4. McAlister, K.W

  4. High pressure apparatus transport properties study in high magnetic field

    Czech Academy of Sciences Publication Activity Database

    Honda, F.; Sechovský, V.; Mikulina, O.; Kamarád, Jiří; Alsmadi, A. M.; Nakotte, H.; Lacerda, A. H.

    2002-01-01

    Roč. 16, 20, 21 & 22 (2002), s. 3330-3333 ISSN 0217-9792 R&D Projects: GA ČR GP202/01/D045; GA ČR GA202/00/1217; GA MŠk ME 165 Grant - others:NSF(XX) DMR-0094241 Institutional research plan: CEZ:AV0Z1010914 Keywords : high-pressure apparatus Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.604, year: 2002

  5. Multi-phase-field method for surface tension induced elasticity

    Science.gov (United States)

    Schiedung, Raphael; Steinbach, Ingo; Varnik, Fathollah

    2018-01-01

    A method, based on the multi-phase-field framework, is proposed that adequately accounts for the effects of a coupling between surface free energy and elastic deformation in solids. The method is validated via a number of analytically solvable problems. In addition to stress states at mechanical equilibrium in complex geometries, the underlying multi-phase-field framework naturally allows us to account for the influence of surface energy induced stresses on phase transformation kinetics. This issue, which is of fundamental importance on the nanoscale, is demonstrated in the limit of fast diffusion for a solid sphere, which melts due to the well-known Gibbs-Thompson effect. This melting process is slowed down when coupled to surface energy induced elastic deformation.

  6. Efficiency of Magnetic Field Treatment on Pressure Sores in Bedridden Patients

    Directory of Open Access Journals (Sweden)

    Ferda Özdemir

    2011-09-01

    Full Text Available Objective: Pressure sores are an important source of complications in patients who are immobilized and bedridden. We aimed to investigate the efficiency of magnetic field treatment in pressure sores. Material and Methods: This was a randomized, double blind controlled design study. 20 patients in the study group received magneto-therapy, once a day for 30 minutes and with 150G, keeping to the BTL09 magnetotherapy device’s program. In the control group, 20 patients received the dressing only once a day. The surface areas of the pressure sores were evaluated at the onset of the treatment (1st day, and on the 7th and 15th days.Results: When within group comparisons were conducted, a significant difference was observed between the 1st and 7th day, 7th and 15th day, and 1st and 15th day measures in both the groups in terms of the scar area. The average healing time for the treatment group was 10.80±4.06 (6-20 days, and the average healing time for the control group was 18.85±9.75 (5-32 days. There was a statistically significant difference between the two groups (z=-2.114, p=0.034. Also, there was a significant difference in the scar area between the two groups in the 15th day measure (z=-3.818, p=0.000.Conclusion: The healing process of the tissue can be accelerated.with the use of magnetotherapy in the treatment of pressure sores of stage II and III,

  7. Reneutralization time of surface silicon ions on a field emitter

    International Nuclear Information System (INIS)

    Mazumder, B; Vella, A; Deconihout, B; Gilbert, M; Schmitz, G

    2010-01-01

    In this work, the lifetime of silicon (Si) ions generated through photoionization of Si surface atoms from a field emitter was measured. Under low-intensity fs laser pulse illumination, a linear dependence of the number of evaporated ions per pulse on the laser intensity was observed. A simple model was developed to explain this linear dependence and to estimate the rate of success of the field evaporation process. It is shown that the number of evaporated ions per pulse depends on the standing field applied to the Si surface, demonstrating the existence of an ionic energy barrier for Si ions. The lifetime of these ions was estimated to be 0.5 ps.

  8. Methodology to estimate the relative pressure field from noisy experimental velocity data

    International Nuclear Information System (INIS)

    Bolin, C D; Raguin, L G

    2008-01-01

    The determination of intravascular pressure fields is important to the characterization of cardiovascular pathology. We present a two-stage method that solves the inverse problem of estimating the relative pressure field from noisy velocity fields measured by phase contrast magnetic resonance imaging (PC-MRI) on an irregular domain with limited spatial resolution, and includes a filter for the experimental noise. For the pressure calculation, the Poisson pressure equation is solved by embedding the irregular flow domain into a regular domain. To lessen the propagation of the noise inherent to the velocity measurements, three filters - a median filter and two physics-based filters - are evaluated using a 2-D Couette flow. The two physics-based filters outperform the median filter for the estimation of the relative pressure field for realistic signal-to-noise ratios (SNR = 5 to 30). The most accurate pressure field results from a filter that applies in a least-squares sense three constraints simultaneously: consistency between measured and filtered velocity fields, divergence-free and additional smoothness conditions. This filter leads to a 5-fold gain in accuracy for the estimated relative pressure field compared to without noise filtering, in conditions consistent with PC-MRI of the carotid artery: SNR = 5, 20 x 20 discretized flow domain (25 X 25 computational domain).

  9. Pressure-redistribution surfaces for prevention of surgery-related pressure ulcers: a meta-analysis .

    Science.gov (United States)

    Huang, Hai-Yan; Chen, Hong-Lin; Xu, Xu-Juan

    2013-04-01

    Pressure-redistribution surfaces are generally recommended to prevent pressure ulcers (PUs) in high-risk patients, but their use in surgery-related PU prevention remains controversial. A meta-analysis was conducted to assess the relative preventive impact of pressure-redistribution surfaces versus standard hospital mattresses (usually a hospital-issue, foam-based mattress) on the incidence of surgery-related PUs. Systematic literature searches were performed using the terms pressure ulcer, operation, surgery, mattress, foam, polymer, pad, overlay, surface, and interface. Country, race, language, and publication year of articles was not restricted; randomized or quasi-randomized controlled trials were eligible for analysis. Odds ratio (OR) with 95% confidence intervals (CIs) for surgery-related PU incidence in patients using support surfaces versus standard mattress were calculated by random-effects model. Of the 316 studies identified, 10 involving a total of 1,895 patients were eligible for inclusion in the meta-analysis. Seven studies were randomized, controlled and three were quasi-randomized controlled trials. Patients who were provided a support surface had a significantly decreased incidence of surgery-related PUs (OR 0.31 [95% CI 0.17-0.59]) compared to patients using a standard mattress. Subgroup analysis showed pressure-redistribution surfaces used intra-operatively did not decrease the incidence of surgery-related PUs (OR 0.59, [95% CI 0.34-1.01]), but PU incidence decreased with postoperative (OR 0.07 [95% CI 0.01-0.49]) as well as with intra-operative and postoperative use (OR 0.20 [95% CI 0.06-0.73]). Funnel plot diagrams suggest a minimal risk of bias. Sensitivity analysis did not materially change the result of the main metaanalysis. Postoperative use of pressure-redistribution surfaces can effectively decrease the incidence of surgery-related PUs, but evidence to substantiate intra-operative use is insufficient. Patients at high risk for surgery

  10. Surface Pressure Measurements of Atmospheric Tides Using Smartphones

    Science.gov (United States)

    Price, Colin; Maor, Ron

    2017-04-01

    Similar to the oceans, the atmosphere also has tides that are measured in variations of atmospheric pressure. However, unlike the gravitational tides in the oceans, the atmospheric tides are caused primarily in the troposphere and stratosphere when the atmosphere is periodically heated by the sun, due to tropospheric absorption by water vapor and stratospheric absorption by ozone. Due to the forcing being always on the day side of the globe, the tides migrate around the globe following the sun (migrating tides) with a dominant periodicity of 12 hours (and less so at 24 hours). In recent years smartphones have been equipped with sensitive, cheap and reliable pressure sensors that can easily detect these atmospheric tides. By 2020 it is expected that there will be more than 6 billion smartphones globally, each measuring continuously atmospheric pressure at 1Hz temporal resolution. In this presentation we will present some control experiments we have performed with smartphones to monitor atmospheric tides, while also using random pressure data from more than 50,000 daily users via the WeatherSignal application. We conclude that smartphones are a useful tool for studying atmospheric tides on local and global scales.

  11. Modelling surface pressure fluctuation on medium-rise buildings

    NARCIS (Netherlands)

    Snæbjörnsson, J.T.; Geurts, C.P.W.

    2006-01-01

    This paper describes the results of two experiments into the fluctuating characteristics of windinduced pressures on buildings in a built-up environment. The experiments have been carried out independently in Iceland and The Netherlands and can be considered to represent two separate cases of

  12. Surface modification of polylactic acid films by atmospheric pressure plasma treatment

    Science.gov (United States)

    Kudryavtseva, V. L.; Zhuravlev, M. V.; Tverdokhlebov, S. I.

    2017-09-01

    A new approach for the modification of polylactic acid (PLA) materials using atmospheric pressure plasma (APP) is described. PLA films plasma exposure time was 20, 60, 120 s. The surface morphology and wettability of the obtained PLA films were investigated by atomic force microscopy (AFM) and the sitting drop method. The atmospheric pressure plasma increased the roughness and surface energy of PLA film. The wettability of PLA has been improved with the application of an atmospheric plasma surface treatment. It was shown that it is possible to obtain PLA films with various surface relief and tunable wettability. Additionally, we demonstrated that the use of cold atmospheric pressure plasma for surface activation allows for the immobilization of bioactive compounds like hyaluronic acid (HA) on the surface of obtained films. It was shown that composite PLA-HA films have an increased long-term hydrophilicity of the films surface.

  13. Influence of Surface Energy Effects on Elastic Fields of a Layered Elastic Medium under Surface Loading

    Directory of Open Access Journals (Sweden)

    Supakorn Tirapat

    2017-01-01

    Full Text Available This paper presents the analysis of a layered elastic half space under the action of axisymmetric surface loading and the influence of the surface energy effects. The boundary value problems for the bulk and the surface are formulated based on classical linear elasticity and a complete Gurtin-Murdoch constitutive relation. An analytical technique using Love’s representation and the Hankel integral transform is employed to derive an integral-form solution for both displacement and stress fields. An efficient numerical quadrature is then applied to accurately evaluate all involved integrals. Selected numerical results are presented to portray the influence of various parameters on elastic fields. Numerical results indicate that the surface stress displays a significant influence on both displacement and stress fields. It is also found that the layered half space becomes stiffer with the presence of surface stresses. In addition, unlike the classical elasticity solution, size-dependent behavior of elastic fields is noted. The present analytical solutions provide fundamental understanding of the influence of surface energy on layered elastic materials. It can also be used as a benchmark solution for the development of numerical techniques such as FEM and BEM, for analysis of more complex problems involving a layered medium under the influence of surface energy effects.

  14. Magnetic-field- and pressure-induced quantum phases in complex materials.

    Science.gov (United States)

    Kim, Minjung; Barath, Harini; Chen, Xiaoqian; Joe, Young-Il; Fradkin, Eduardo; Abbamonte, Peter; Cooper, S Lance

    2010-03-12

    This Progress Report presents temperature-, magnetic-field-, and pressure-dependent Raman measurements of strongly correlated materials such as the charge-ordering manganese perovskites, the multiferroic material TbMnO(3), and the charge-density wave (CDW) materials 1T-TiSe(2) and Cu(x)TiSe(2). These studies illustrate the rich array of phases and properties that can be accessed with field and pressure tuning in these materials, and demonstrate the efficacy of using magnetic-field- and pressure-dependent scattering methods to elucidate the microscopic changes associated with highly tunable behavior in complex materials.

  15. Magnetic-field control of low-pressure diffuse discharges

    International Nuclear Information System (INIS)

    Cooper, J.R.

    1986-01-01

    Application of a magnetic field in a direction transverse to the electric field in a diffuse discharge can have a strong effect on the transport parameters in the discharge medium and on the external characteristics of the discharge as a whole. Deviations in these transport parameters were investigated in this work by means of Monte Carlo calculations, and the electrical characteristics of the total discharge were observed experimentally. Results of the theoretical investigation show that, in attaching gas mixtures, both the ionization and attachment-rate coefficients in the positive column of the discharge are changed such that the combined effect results in an increase in resistivity. Experimentally, it is seen that application of a crossed magnetic field to an abnormal glow discharge in attaching gases in a certain parameter range causes the discharge voltage to increase significantly. The effect seems to be most strongly influenced by processes in the cathode-fall region

  16. Microstructural and hardness gradients in Cu processed by high pressure surface rolling

    DEFF Research Database (Denmark)

    He, Q. Y.; Zhu, X.-M.; Mei, Q. S.

    2017-01-01

    The surface of an annealed Cu plate was processed by a high pressure surface rolling (HPSR) process. It is found that the deformed surface layer in the Cu plate after HPSR can be as thick as 2 mm and is characterized by a gradient microstructure, with grain sizes varying from the nanoscale...

  17. Surface-ionization field mass-spectrometry studies of nonequilibrium surface ionization

    International Nuclear Information System (INIS)

    Blashenkov, Nikolai M; Lavrent'ev, Gennadii Ya

    2007-01-01

    The ionization of polyatomic molecules on tungsten and tungsten oxide surfaces is considered for quasiequilibrium or essentially nonequilibrium conditions (in the latter case, the term nonequilibrium surface ionization is used for adsorbate ionization). Heterogeneous reactions are supposed to proceed through monomolecular decay of polyatomic molecules or fragments of multimolecular complexes. The nonequilibrium nature of these reactions is established. The dependences of the current density of disordered ions on the surface temperature, electric field strength, and ionized particle energy distribution are obtained in analytical form. Heterogeneous dissociation energies, the ionization potentials of radicals, and the magnitude of reaction departure from equilibrium are determined from experimental data, as are energy exchange times between reaction products and surfaces, the number of molecules in molecular complexes, and the number of effective degrees of freedom in molecules and complexes. In collecting the data a new technique relying on surface-ionization field mass-spectrometry was applied. (instruments and methods of investigation)

  18. Surface and Flow Field Measurements on the FAITH Hill Model

    Science.gov (United States)

    Bell, James H.; Heineck, James T.; Zilliac, Gregory; Mehta, Rabindra D.; Long, Kurtis R.

    2012-01-01

    A series of experimental tests, using both qualitative and quantitative techniques, were conducted to characterize both surface and off-surface flow characteristics of an axisymmetric, modified-cosine-shaped, wall-mounted hill named "FAITH" (Fundamental Aero Investigates The Hill). Two separate models were employed: a 6" high, 18" base diameter machined aluminum model that was used for wind tunnel tests and a smaller scale (2" high, 6" base diameter) sintered nylon version that was used in the water channel facility. Wind tunnel and water channel tests were conducted at mean test section speeds of 165 fps (Reynolds Number based on height = 500,000) and 0.1 fps (Reynolds Number of 1000), respectively. The ratio of model height to boundary later height was approximately 3 for both tests. Qualitative techniques that were employed to characterize the complex flow included surface oil flow visualization for the wind tunnel tests, and dye injection for the water channel tests. Quantitative techniques that were employed to characterize the flow included Cobra Probe to determine point-wise steady and unsteady 3D velocities, Particle Image Velocimetry (PIV) to determine 3D velocities and turbulence statistics along specified planes, Pressure Sensitive Paint (PSP) to determine mean surface pressures, and Fringe Imaging Skin Friction (FISF) to determine surface skin friction (magnitude and direction). This initial report summarizes the experimental set-up, techniques used, data acquired and describes some details of the dataset that is being constructed for use by other researchers, especially the CFD community. Subsequent reports will discuss the data and their interpretation in more detail

  19. Instantaneous Pressure Field Calculation from PIV Data with Least-Square Reconstruction

    Science.gov (United States)

    Zhang, Jiacheng; Scalo, Carlo; Vlachos, Pavlos

    2016-11-01

    A method using least-square reconstruction of instantaneous pressure fields from PIV velocity measurements is introduced and applied to both planar and volumetric flow data. Pressure gradients are computed on a staggered grid from flow acceleration. An overdetermined system of linear equations which relates the pressure and the computed pressure gradients is formulated. The pressure field is estimated as the least-square solution of the overdetermined system. The flow acceleration is approximated by the vortex-in-cell procedure, providing the pressure field from a single velocity snapshot. The least-square method is compared against the omni-directional pressure gradient integration and solving the pressure Poisson equation. The results demonstrate that the omni-directional integration and the least-square method are more robust to the noise in velocity measurements than the pressure Poisson solver. In addition, the computational cost of the least square method is much lower than the omni-directional integration, and very easily extendable to volumetric data retaining computational efficiency. The least-square method maintains higher accuracy than the pressure Poisson equation while retaining a similar computational burden.

  20. Io meteorology - How atmospheric pressure is controlled locally by volcanos and surface frosts

    Science.gov (United States)

    Ingersoll, Andrew P.

    1989-01-01

    The present modification of the Ingersoll et al. (1985) hydrodynamic model of the SO2 gas sublimation-driven flow from the day to the night side of Io includes the effects of nonuniform surface properties noted in observational studies. Calculations are conducted for atmospheric pressures, horizontal winds, sublimation rates, and condensation rates for such surface conditions as patchy and continuous frost cover, volcanic venting, surface temperature discontinuities, subsurface cold trapping, and the propagation of insolation into the frost. While pressure is found to follow local vapor pressure away from the plumes, it becomes higher inside them.

  1. Superresolution near-field imaging with surface waves

    Science.gov (United States)

    Fu, Lei; Liu, Zhaolun; Schuster, Gerard

    2018-02-01

    We present the theory for near-field superresolution imaging with surface waves and time reverse mirrors (TRMs). Theoretical formulae and numerical results show that applying the TRM operation to surface waves in an elastic half-space can achieve superresolution imaging of subwavelength scatterers if they are located less than about 1/2 of the shear wavelength from the source line. We also show that the TRM operation for a single frequency is equivalent to natural migration, which uses the recorded data to approximate the Green's functions for migration, and only costs O(N4) algebraic operations for post-stack migration compared to O(N6) operations for natural pre-stack migration. Here, we assume the sources and receivers are on an N × N grid and there are N2 trial image points on the free surface. Our theoretical predictions of superresolution are validated with tests on synthetic data. The field-data tests suggest that hidden faults at the near surface can be detected with subwavelength imaging of surface waves by using the TRM operation if they are no deeper than about 1/2 the dominant shear wavelength.

  2. Superresolution Near-field Imaging with Surface Waves

    KAUST Repository

    Fu, Lei

    2017-10-21

    We present the theory for near-field superresolution imaging with surface waves and time reverse mirrors (TRMs). Theoretical formulas and numerical results show that applying the TRM operation to surface waves in an elastic half-space can achieve superresolution imaging of subwavelength scatterers if they are located less than about 1/2 of the shear wavelength from the source line. We also show that the TRM operation for a single frequency is equivalent to natural migration, which uses the recorded data to approximate the Green’s functions for migration, and only costs O(N4) algebraic operations for poststack migration compared to O(N6) operations for natural prestack migration. Here, we assume the sources and receivers are on an N × N grid and there are N2 trial image points on the free surface. Our theoretical predictions of superresolution are validated with tests on synthetic data. The field-data tests suggest that hidden faults at the near surface can be detected with subwavelength imaging of surface waves by using the TRM operation if they are no deeper than about 1/2 the dominant shear wavelength.

  3. Assessing Asphalt and Concrete Pavement Surface Texture in the Field

    Directory of Open Access Journals (Sweden)

    Saad I. Sarsam

    2016-06-01

    Full Text Available The incorporation of safety characteristics into the traditional pavement structural design or in the functional evaluation of pavement condition has not been established yet. The design has focused on the structural capacity of the roadway so that the pavement can withstand specific level of repetitive loading over the design life. On the other hand, the surface texture condition was neither included in the AASHTO design procedure nor in the present serviceability index measurements. The pavement surface course should provide adequate levels of friction and ride quality and maintain low levels of noise and roughness. Many transportation departments perform routine skid resistant testing, the type of equipment used for testing varies depending on the preference of each transportation department. It was felt that modeling of the surface texture condition using different methods of testing may assist in solving such problem. In this work, Macro texture and Micro texture of asphalt and cement concrete pavement surface have been investigated in the field using four different methods (The Sand Patch Method, Outflow Time Method, British Pendulum Tester and Photogrammetry Technique. Two different grain sizes of sand have been utilized in conducting the Sand Patch while the Micro texture was investigated using the British Pendulum tester method at wet pavement surface conditions. The test results of the four methods were correlated to the skid number. It was concluded that such modeling could provide instant data in the field for pavement condition which may help in pavement maintenance management.

  4. Influence of Pressure Field in Melts on the Primary Nucleation in Solidification Processing

    Science.gov (United States)

    Rakita, Milan; Han, Qingyou

    2017-10-01

    It is well known that external fields applied to melts can cause nucleation at lower supercoolings, fragmentation of growing dendrites, and forced convection around the solidification front. All these effects contribute to a finer microstructure of solidified material. In this article, we analyze how the pressure field created with ultrasonic vibrations influences structure refinement in terms of supercooling. It is shown that only high cavitation pressures of the order of 104 atmospheres are capable of nucleating crystals at minimal supercoolings. We demonstrate the possibility of sononucleation even in superheated liquid. Simulation and experiments with water samples show that very high cavitation pressures occur in a relatively narrow zone where the drive acoustic field has an appropriate combination of pressure amplitude and frequency. In order to accurately predict the microstructure formed by ultrasonically assisted solidification of metals, this article calls for the development of equations of state that would describe the pressure-dependent behavior of molten metals.

  5. [Analysis of statutory health insurance data concerning utilization of support surfaces for pressure ulcers].

    Science.gov (United States)

    Hoffmann, Falk; Scharnetzky, Elke; Deitermann, Bernhilde; Glaeske, Gerd

    2006-10-01

    Support surfaces are commonly used to prevent and treat pressure ulcers. Up to now little is known about their application in Germany. We conducted a cross-sectional study using claims data of the Gmuender ErsatzKasse (GEK) for the year 2004 to analyse the utilization of support surfaces for pressure ulcers in primary care. Based on age- and sex-specific treatment prevalences for individuals with at least one prescription, prevalence ratios (PR) were calculated. A total of 1999 subjects with a mean age of 63.4 years (SD: 20.7) received support surfaces for pressure ulcers. With respect to the numbers of prescriptions (n = 2421) alternating pressure mattresses (31.6%), air-filled rings (13.5%) and various seat cushions (13.0%) were used frequently, whereas foam mattresses only came to 4.7%. The treatment prevalence increases continuously with age with no sex-specific differences. Using the 50-59 year olds as a reference, men aged 90+ (PR: 43.94; 95% CI: 31.46-61.37) as well as women aged 90+ (PR: 40.61; 95% CI: 30.77-53.60) received approximately 40-times more often support surfaces for pressure ulcers. Support surfaces for pressure ulcers are commonly used in the elderly. Our study suggests that their application does not correspond to the best available evidence. Prevention and treatment of pressure ulcers as well as the selection of support surfaces should be seen as an interdisciplinary task.

  6. Causes of plasma column contraction in surface-wave-driven discharges in argon at atmospheric pressure

    Science.gov (United States)

    Ridenti, Marco Antonio; de Amorim, Jayr; Dal Pino, Arnaldo; Guerra, Vasco; Petrov, George

    2018-01-01

    In this work we compute the main features of a surface-wave-driven plasma in argon at atmospheric pressure in view of a better understanding of the contraction phenomenon. We include the detailed chemical kinetics dynamics of Ar and solve the mass conservation equations of the relevant neutral excited and charged species. The gas temperature radial profile is calculated by means of the thermal diffusion equation. The electric field radial profile is calculated directly from the numerical solution of the Maxwell equations assuming the surface wave to be propagating in the TM00 mode. The problem is considered to be radially symmetrical, the axial variations are neglected, and the equations are solved in a self-consistent fashion. We probe the model results considering three scenarios: (i) the electron energy distribution function (EEDF) is calculated by means of the Boltzmann equation; (ii) the EEDF is considered to be Maxwellian; (iii) the dissociative recombination is excluded from the chemical kinetics dynamics, but the nonequilibrium EEDF is preserved. From this analysis, the dissociative recombination is shown to be the leading mechanism in the constriction of surface-wave plasmas. The results are compared with mass spectrometry measurements of the radial density profile of the ions Ar+ and Ar2+. An explanation is proposed for the trends seen by Thomson scattering diagnostics that shows a substantial increase of electron temperature towards the plasma borders where the electron density is small.

  7. Rapid Transient Pressure Field Computations in the Nearfield of Circular Transducers using Frequency Domain Time-Space Decomposition

    Science.gov (United States)

    Alles, E. J.; Zhu, Y.; van Dongen, K. W. A.; McGough, R. J.

    2013-01-01

    The fast nearfield method, when combined with time-space decomposition, is a rapid and accurate approach for calculating transient nearfield pressures generated by ultrasound transducers. However, the standard time-space decomposition approach is only applicable to certain analytical representations of the temporal transducer surface velocity that, when applied to the fast nearfield method, are expressed as a finite sum of products of separate temporal and spatial terms. To extend time-space decomposition such that accelerated transient field simulations are enabled in the nearfield for an arbitrary transducer surface velocity, a new transient simulation method, frequency domain time-space decomposition (FDTSD), is derived. With this method, the temporal transducer surface velocity is transformed into the frequency domain, and then each complex-valued term is processed separately. Further improvements are achieved by spectral clipping, which reduces the number of terms and the computation time. Trade-offs between speed and accuracy are established for FDTSD calculations, and pressure fields obtained with the FDTSD method for a circular transducer are compared to those obtained with Field II and the impulse response method. The FDTSD approach, when combined with the fast nearfield method and spectral clipping, consistently achieves smaller errors in less time and requires less memory than Field II or the impulse response method. PMID:23160476

  8. Rapid transient pressure field computations in the nearfield of circular transducers using frequency-domain time-space decomposition.

    Science.gov (United States)

    Alles, E J; Zhu, Y; van Dongen, K W A; McGough, R J

    2012-10-01

    The fast nearfield method, when combined with time-space decomposition, is a rapid and accurate approach for calculating transient nearfield pressures generated by ultrasound transducers. However, the standard time-space decomposition approach is only applicable to certain analytical representations of the temporal transducer surface velocity that, when applied to the fast nearfield method, are expressed as a finite sum of products of separate temporal and spatial terms. To extend time-space decomposition such that accelerated transient field simulations are enabled in the nearfield for an arbitrary transducer surface velocity, a new transient simulation method, frequency-domain time-space decomposition (FDTSD), is derived. With this method, the temporal transducer surface velocity is transformed into the frequency domain, and then each complex-valued term is processed separately. Further improvements are achieved by spectral clipping, which reduces the number of terms and the computation time. Trade-offs between speed and accuracy are established for FDTSD calculations, and pressure fields obtained with the FDTSD method for a circular transducer are compared with those obtained with Field II and the impulse response method. The FDTSD approach, when combined with the fast nearfield method and spectral clipping, consistently achieves smaller errors in less time and requires less memory than Field II or the impulse response method.

  9. Effect of magnetic field on oxygen pressure, radiosensitivity and growth of some experimental tumors

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, B.N.; Kauashev, S.K.

    The effect of variation of partial oxygen pressure in liquid media and directly in living tumors was investigated to determine the effect of a permanent magnetic field on these changes. Partial oxygen pressure increases significantly in Pliss lymphosarcoma and RS-1 tumors when exposed to a magnetic field and decreases after the magnetic field is removed. The variation of partial oxygen pressure is similar in Walker carcinosarcoma, but is different for living and killed rats. The growth rate of tumors decreases appreciably after each session of combination magnetic and radiation effects with an increase of partial oxygen pressure in magnetized tumors. Periodic one-hour magnetic exposure preceding irradiation causes a marked zigzag growth of tumors, while 5- and 30- minute exposure to a permanent magnetic field has essentially no effect on tumor growth.

  10. Synthesis and atmospheric pressure field emission operation of W18O49 nanowires

    NARCIS (Netherlands)

    Agiral, A.; Gardeniers, Johannes G.E.

    2008-01-01

    Tungsten oxide W18O49 nanorods with diameters of 15−20 nm were grown on tungsten thin films exposed to ethene and nitrogen at 700 °C at atmospheric pressure. It was found that tungsten carbide formation enhances nucleation and growth of nanorods. Atmospheric pressure field emission measurements in

  11. Pressure and compressibility of a quantum plasma in a magnetic field

    NARCIS (Netherlands)

    Suttorp, L.G.

    1993-01-01

    The equilibrium pressure tensor that occurs in the momentum balance equation for a quantum plasma in a magnetic field is shown to be anisotropic. Its relation to the pressure that follows from thermodynamics is elucidated. A general proof of the compressibility rule for a magnetized quantum plasma

  12. Fault detection by surface seismic scanning tunneling macroscope: Field test

    KAUST Repository

    Hanafy, Sherif M.

    2014-08-05

    The seismic scanning tunneling macroscope (SSTM) is proposed for detecting the presence of near-surface impedance anomalies and faults. Results with synthetic data are consistent with theory in that scatterers closer to the surface provide brighter SSTM profiles than those that are deeper. The SSTM profiles show superresolution detection if the scatterers are in the near-field region of the recording line. The field data tests near Gulf of Aqaba, Haql, KSA clearly show the presence of the observable fault scarp, and identify the subsurface presence of the hidden faults indicated in the tomograms. Superresolution detection of the fault is achieved, even when the 35 Hz data are lowpass filtered to the 5-10 Hz band.

  13. Pressure RElieving Support SUrfaces: a Randomised Evaluation 2 (PRESSURE 2): study protocol for a randomised controlled trial.

    Science.gov (United States)

    Brown, Sarah; Smith, Isabelle L; Brown, Julia M; Hulme, Claire; McGinnis, Elizabeth; Stubbs, Nikki; Nelson, E Andrea; Muir, Delia; Rutherford, Claudia; Walker, Kay; Henderson, Valerie; Wilson, Lyn; Gilberts, Rachael; Collier, Howard; Fernandez, Catherine; Hartley, Suzanne; Bhogal, Moninder; Coleman, Susanne; Nixon, Jane E

    2016-12-20

    Pressure ulcers represent a major burden to patients, carers and the healthcare system, affecting approximately 1 in 17 hospital and 1 in 20 community patients. They impact greatly on an individual's functional status and health-related quality of life. The mainstay of pressure ulcer prevention practice is the provision of pressure redistribution support surfaces and patient repositioning. The aim of the PRESSURE 2 study is to compare the two main mattress types utilised within the NHS: high-specification foam and alternating pressure mattresses, in the prevention of pressure ulcers. PRESSURE 2 is a multicentre, open-label, randomised, double triangular, group sequential, parallel group trial. A maximum of 2954 'high-risk' patients with evidence of acute illness will be randomised on a 1:1 basis to receive either a high-specification foam mattress or alternating-pressure mattress in conjunction with an electric profiling bed frame. The primary objective of the trial is to compare mattresses in terms of the time to developing a new Category 2 or above pressure ulcer by 30 days post end of treatment phase. Secondary endpoints include time to developing new Category 1 and 3 or above pressure ulcers, time to healing of pre-existing Category 2 pressure ulcers, health-related quality of life, cost-effectiveness, incidence of mattress change and safety. Validation objectives are to determine the responsiveness of the Pressure Ulcer Quality of Life-Prevention instrument and the feasibility of having a blinded endpoint assessment using photography. The trial will have a maximum of three planned analyses with unequally spaced reviews at event-driven coherent cut-points. The futility boundaries are constructed as non-binding to allow a decision for stopping early to be overruled by the Data Monitoring and Ethics Committee. The double triangular, group sequential design of the PRESSURE 2 trial will provide an efficient design through the possibility of early stopping for

  14. High Sensitivity Semiconductor Sensor Skins for Multi-Axis Surface Pressure Characterization, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA Phase II SBIR program would fabricate high sensitivity semiconductor nanomembrane 'sensor skins' capable of multi-axis surface pressure characterization on...

  15. High Sensitivity Semiconductor Sensor Skins for Multi-Axis Surface Pressure Characterization, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA Phase I SBIR program would fabricate high sensitivity semiconductor nanomembrane 'sensor skins' capable of multi-axis surface pressure characterization on...

  16. Fluorination of poly(dimethylsiloxane) surfaces by low pressure CF4 plasma : physicochemical and antifouling properties

    NARCIS (Netherlands)

    Cordeiro, A.L.; Nitschke, M.; Janke, A.; Helbig, R.; D'Souza, F.; Donnelly, G.T.; Willemsen, P.R.; Werner, C.

    2009-01-01

    Fluorinated surface groups were introduced into poly(dimethylsiloxane) (PDMS) coatings by plasma treatment using a low pressure radio frequency discharge operated with tetrafluoromethane. Substrates were placed in a remote position downstream the discharge. Discharge power and treatment time were

  17. Hydrophilic surface modification of coronary stent using an atmospheric pressure plasma jet for endothelialization.

    Science.gov (United States)

    Shim, Jae Won; Bae, In-Ho; Park, Dae Sung; Lee, So-Youn; Jang, Eun-Jae; Lim, Kyung-Seob; Park, Jun-Kyu; Kim, Ju Han; Jeong, Myung Ho

    2018-03-01

    The first two authors contributed equally to this study. Bioactivity and cell adhesion properties are major factors for fabricating medical devices such as coronary stents. The aim of this study was to evaluate the advantages of atmospheric-pressure plasma jet in enhancing the biocompatibility and endothelial cell-favorites. The experimental objects were divided into before and after atmospheric-pressure plasma jet treatment with the ratio of nitrogen:argon = 3:1, which is similar to air. The treated surfaces were basically characterized by means of a contact angle analyzer for the activation property on their surfaces. The effect of atmospheric-pressure plasma jet on cellular response was examined by endothelial cell adhesion and XTT analysis. It was difficult to detect any changeable morphology after atmospheric-pressure plasma jet treatment on the surface. The roughness was increased after atmospheric-pressure plasma jet treatment compared to nonatmospheric-pressure plasma jet treatment (86.781 and 7.964 nm, respectively). The X-ray photoelectron spectroscopy results showed that the surface concentration of the C-O groups increased slightly from 6% to 8% after plasma activation. The contact angle dramatically decreased in the atmospheric-pressure plasma jet treated group (22.6 ± 15.26°) compared to the nonatmospheric-pressure plasma jet treated group (72.4 ± 15.26°) ( n = 10, p atmospheric-pressure plasma jet on endothelial cell migration and proliferation was 85.2% ± 12.01% and 34.2% ± 2.68%, respectively, at 7 days, compared to the nonatmospheric-pressure plasma jet treated group (58.2% ± 11.44% in migration, n = 10, p atmospheric-pressure plasma jet method. Moreover, the atmospheric-pressure plasma jet might affect re-endothelialization after stenting.

  18. Cleaning of niobium surface by plasma of diffuse discharge at atmospheric pressure

    Science.gov (United States)

    Tarasenko, V. F.; Erofeev, M. V.; Shulepov, M. A.; Ripenko, V. S.

    2017-07-01

    Elements composition of niobium surface before and after plasma treatment by runaway electron preionized diffuse discharge was investigated in atmospheric pressure nitrogen flow by means of an Auger electron spectroscopy. Surface characterizations obtained from Auger spectra show that plasma treatment by diffuse discharge after exposure of 120000 pulses provides ultrafine surface cleaning from carbon contamination. Moreover, the surface free energy of the treated specimens increased up to 3 times, that improve its adhesion property.

  19. Collapse of Langmuir monolayer at lower surface pressure: Effect of hydrophobic chain length

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kaushik, E-mail: kaushikdas2089@gmail.com; Kundu, Sarathi [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035 (India)

    2016-05-23

    Long chain fatty acid molecules (e.g., stearic and behenic acids) form a monolayer on water surface in the presence of Ba{sup 2+} ions at low subphase pH (≈ 5.5) and remain as a monolayer before collapse generally occurs at higher surface pressure (π{sub c} > 50 mN/m). Monolayer formation is verified from the surface pressure vs. area per molecule (π-A) isotherms and also from the atomic force microscopy (AFM) analysis of the films deposited by single upstroke of hydrophilic Si (001) substrate through the monolayer covered water surface. At high subphase pH (≈ 9.5), barium stearate molecules form multilayer structure at lower surface pressure which is verified from the π-A isotherms and AFM analysis of the film deposited at 25 mN/m. Such monolayer to multilayer structure formation or monolayer collapse at lower surface pressure is unusual as at this surface pressure generally fatty acid salt molecules form a monolayer on the water surface. Formation of bidentate chelate coordination in the metal containing headgroups is the reason for such monolayer to multilayer transition. However, for longer chain barium behenate molecules only monolayer structure is maintained at that high subphase pH (≈ 9.5) due to the presence of relatively more tail-tail hydrophobic interaction.

  20. Surface pressure model for simple delta wings at high angles of attack

    Indian Academy of Sciences (India)

    A new aerodynamic modelling approach is proposed for the longitudinal static characteristics of a simple delta wing. It captures the static variation of normal force and pitching moment characteristics throughout the angle of attack range. The pressure model is based on parametrizing the surface pressure distribution on a ...

  1. Surface wave multipath signals in near-field microwave imaging.

    Science.gov (United States)

    Meaney, Paul M; Shubitidze, Fridon; Fanning, Margaret W; Kmiec, Maciej; Epstein, Neil R; Paulsen, Keith D

    2012-01-01

    Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.

  2. Surface Wave Multipath Signals in Near-Field Microwave Imaging

    Directory of Open Access Journals (Sweden)

    Paul M. Meaney

    2012-01-01

    Full Text Available Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.

  3. Field emission techniques for studying surface reactions: applying them to NO-H2 interaction with Pd tips.

    Science.gov (United States)

    Visart de Bocarmé, T; Kruse, Norbert

    2011-05-01

    The adsorption of NO and its reaction with H(2) over Pd tips were investigated by means of field ion microscopy (FIM) and pulsed field desorption mass spectrometry (PFDMS) in the 10(-3)Pa pressure range and at sample temperatures between 400 and 600K. By varying the H(2) partial pressure while keeping the other control parameters constant, the NO+H(2) reaction over Pd crystallites is shown to exhibit a strong hysteresis effect. The hysteresis region narrows with increase in temperature and the H(2) pressures delimiting this hysteresis decrease as well. Abrupt transformations of the micrographs are observed by FIM from bright to dark patterns and vice versa. These transformations define the hysteresis region. The collected data allow establishing a novel kinetic phase diagram of the NO+H(2)/Pd system within the range of temperatures and pressures indicated. The observed features are correlated with a local chemical analysis by means of field pulses. NO(+) seems to be the dominating imaging species under all conditions. At high relative H(2) pressures (the "hydrogen-side"), H atoms seem to diffuse subsurface. This process is blocked at lower H(2) pressure (the "NO-side") due to NO(ad) and O(ad) accumulation on the surface. Probe-hole measurements with field pulses indicate that the Pd surface undergoes oxidation as revealed by the occurrence of PdO(2)(+) species in the mass spectra. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Mesogranulation and the Solar Surface Magnetic Field Distribution

    Science.gov (United States)

    Yelles Chaouche, L.; Moreno-Insertis, F.; Martínez Pillet, V.; Wiegelmann, T.; Bonet, J. A.; Knölker, M.; Bellot Rubio, L. R.; del Toro Iniesta, J. C.; Barthol, P.; Gandorfer, A.; Schmidt, W.; Solanki, S. K.

    2011-02-01

    The relation of the solar surface magnetic field with mesogranular cells is studied using high spatial (≈100 km) and temporal (≈30 s) resolution data obtained with the IMaX instrument on board SUNRISE. First, mesogranular cells are identified using Lagrange tracers (corks) based on horizontal velocity fields obtained through local correlation tracking. After ≈20 minutes of integration, the tracers delineate a sharp mesogranular network with lanes of width below about 280 km. The preferential location of magnetic elements in mesogranular cells is tested quantitatively. Roughly 85% of pixels with magnetic field higher than 100 G are located in the near neighborhood of mesogranular lanes. Magnetic flux is therefore concentrated in mesogranular lanes rather than intergranular ones. Second, magnetic field extrapolations are performed to obtain field lines anchored in the observed flux elements. This analysis, therefore, is independent of the horizontal flows determined in the first part. A probability density function (PDF) is calculated for the distribution of distances between the footpoints of individual magnetic field lines. The PDF has an exponential shape at scales between 1 and 10 Mm, with a constant characteristic decay distance, indicating the absence of preferred convection scales in the mesogranular range. Our results support the view that mesogranulation is not an intrinsic convective scale (in the sense that it is not a primary energy-injection scale of solar convection), but also give quantitative confirmation that, nevertheless, the magnetic elements are preferentially found along mesogranular lanes.

  5. Experimental verification of the role of electron pressure in fast magnetic reconnection with a guide field

    International Nuclear Information System (INIS)

    Fox, W.; Sciortino, F.; Stechow, A. von; Jara-Almonte, J.

    2017-01-01

    We report detailed laboratory observations of the structure of a reconnection current sheet in a two-fluid plasma regime with a guide magnetic field. We observe and quantitatively analyze the quadrupolar electron pressure variation in the ion-diffusion region, as originally predicted by extended magnetohydrodynamics simulations. The projection of the electron pressure gradient parallel to the magnetic field contributes significantly to balancing the parallel electric field, and the resulting cross-field electron jets in the reconnection layer are diamagnetic in origin. Furthermore, these results demonstrate how parallel and perpendicular force balance are coupled in guide field reconnection and confirm basic theoretical models of the importance of electron pressure gradients for obtaining fast magnetic reconnection.

  6. Stabilization of axisymmetric liquid bridges through vibration-induced pressure fields.

    Science.gov (United States)

    Haynes, M; Vega, E J; Herrada, M A; Benilov, E S; Montanero, J M

    2018-03-01

    Previous theoretical studies have indicated that liquid bridges close to the Plateau-Rayleigh instability limit can be stabilized when the upper supporting disk vibrates at a very high frequency and with a very small amplitude. The major effect of the vibration-induced pressure field is to straighten the liquid bridge free surface to compensate for the deformation caused by gravity. As a consequence, the apparent Bond number decreases and the maximum liquid bridge length increases. In this paper, we show experimentally that this procedure can be used to stabilize millimeter liquid bridges in air under normal gravity conditions. The breakup of vibrated liquid bridges is examined experimentally and compared with that produced in absence of vibration. In addition, we analyze numerically the dynamics of axisymmetric liquid bridges far from the Plateau-Rayleigh instability limit by solving the Navier-Stokes equations. We calculate the eigenfrequencies characterizing the linear oscillation modes of vibrated liquid bridges, and determine their stability limits. The breakup process of a vibrated liquid bridge at that stability limit is simulated too. We find qualitative agreement between the numerical predictions for both the stability limits and the breakup process and their experimental counterparts. Finally, we show the applicability of our technique to control the amount of liquid transferred between two solid surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Flow field design for high-pressure PEM electrolysis cells

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Kær, Søren Knudsen

    -water distributes. Water not only serves a reactant, it also aids in cooling due to its high specific heat capacity. The movement of liquid water at the anode is difficult to model, since it is highly coupled to the formation of gas bubbles. To capture the complex two-phase flow behaviour that takes place within...... micro-channels and porous media, our research group has developed an Euler-Euler model in the computational fluid dynamics modelling framework of ANSYS CFX. In addition to two-phase flow, the model accounts for turbulence, species transport in the gas phase, heat transport in all three phases (i.......e. solid, gas and liquid), as well as charge transport of electrons and ions. Our recent improvements have focused on the models ability to account for phase change and electrochemistry as well as the modelling of two-phase flow regimes. For comparison, an interdigitated and parallel channel flow field...

  8. BLAF: A Blast Field Reconstruction Program from Pressure Histories

    Science.gov (United States)

    1985-03-01

    ApRencix C) inis subroutine is called from tne main proqram for blast field nistory calculations and it is the most inmortant subroutine of that...51 S COR(4911.COR(1#41 104 CDR( 293)u DAT(6) S COR(3,2)=COR(2v3) COR2v4)-DATI7) S COR(4#2)&COR(2,’ el 60 COR(3p4)=DAT(8) S COR(4,93)=CORl3,v4) KCLsO...Cl2mO S C22=0 $ RSluO S RS2*0 KK=O DO 105 KCm1,NR 120 . . . .. . . . . . . . . . . . . . . IF(DIST(KC) eLE *0.) GOTO 105 [F(ABS(P(KBPKCIJ.LT.1.E-30

  9. Measurement of electric field distribution along the plasma column in Microwave jet discharges at atmospheric pressure

    International Nuclear Information System (INIS)

    Razzak, M. Abdur; Takamura, Shuichi; Tsujikawa, Takayuki; Shibata, Hideto; Hatakeyama, Yuto

    2009-01-01

    A new technique for the direct measurement of electric field distribution along the plasma column in microwave jet discharges is developed and employed. The technique is based on a servomotor-controlled reciprocating antenna moving along the nozzle axis and plasma column. The measurement technique is applied to a rectangular waveguide-based 2.45 GHz argon and helium plasma jets generated by using the modified TIAGO nozzle at atmospheric pressure with a microwave power of less than 500 W. The measurement has been done with and without igniting the plasma jet in order to investigate the standing wave propagation along the nozzle axis and plasma column. It is observed that the electric field decay occurs slowly in space with plasma ignition than that of without plasma, which indicates the surface electromagnetic wave propagation along the plasma column in order to sustain the plasma jet. This study enables one to design, determine and optimize the size and structure of launcher nozzle, which plays an important role for the stable and efficient microwave plasma generators. (author)

  10. Support surfaces in the prevention of pressure ulcers in surgical patients: An integrative review.

    Science.gov (United States)

    de Oliveira, Karoline Faria; Nascimento, Kleiton Gonçalves; Nicolussi, Adriana Cristina; Chavaglia, Suzel Regina Ribeiro; de Araújo, Cleudmar Amaral; Barbosa, Maria Helena

    2017-08-01

    To assess the scientific evidence about the types of support surfaces used in intraoperative surgical practice in the prevention of pressure ulcers due to surgical positioning. This is an integrative literature review. The electronic databases Cochrane, PubMed, Web of Science, Scopus, Lilacs, and CINAHL were used. The descriptors surgical patients, support surfaces, perioperative care, patient positioning, and pressure ulcer were used in the search strategy. Articles that addressed the use of support surfaces intraoperatively, published between 1990 and 2016, were selected. The PRISMA guidelines were used to structure the review. Of 18 evaluated studies, most were in English, followed by Portuguese and Spanish; most were performed by nurses. The most commonly cited support surfaces were viscoelastic polymer, micropulse mattresses, gel based mattresses, and foam devices. There are gaps in knowledge regarding the most efficient support surfaces and the specifications of the products used to prevent pressure ulcers due to surgical positioning. © 2017 John Wiley & Sons Australia, Ltd.

  11. Application of low pressure plasma technology in the field of environmental protection

    International Nuclear Information System (INIS)

    Sun Yabing

    2000-01-01

    The characteristics of low pressure plasma produced by a gas discharges lie in that the energy of the electrons are much higher than that of the heavy particles in the system. The low-pressure plasma treatment technology for the environmental contaminants was synthetically studied, and the reaction processing and mechanism between the low-pressure plasma and the environmental contaminants were theoretically analyzed. At last, the prospects and existing problems on the application of low-pressure plasma in the field of environmental protection were discussed

  12. Field Comparison of Fertigation Vs. Surface Irrigation of Cotton Crop

    International Nuclear Information System (INIS)

    Janat, M.

    2004-01-01

    Based on previous results of the same nature, one nitrogen rate 180 kg N ha -1 was tested under two-irrigation methods, surface irrigation and drip fertigation of cotton (Cultivar Rakka-5) for two consecutive seasons 2000 and 2001. The study aimed to answer various questions regarding the applicability of drip fertigation at farm level and the effect of its employment on yield and growth parameters, compared to surface irrigation. Nitrogen fertilizer was either injected in eight equally split applications for the drip fertigated cotton or divided in four unequally split applications as recommend by Ministry of Agriculture (20% before planting, 40% at thinning, 20% after 60 days from planting and 20% after 75 days after planting). 15 N labeled urea was used to evaluate nitrogen fertilizer efficiency. The experimental design was randomized block design with seven replicates. Results showed that drip fertigation led to water saving exceeding 50% in some cases. Field germination percentage was highly increased under drip- fertigated cotton relative to surface-irrigated cotton. Dry matter and seed cotton yield of surface-irrigated cotton was slightly higher than that of drip-fertigated cotton in the first growing season. The reason for that was due to the hot spill that occurred in the region, which exposed the cotton crop to water stress and consequently pushed the cotton into early flowering. Lint properties were not affected by the introduction of drip-fertigation. Actually some properties were improved relative to the standard properties identified by the cotton Bureau.Nitrogen uptake was slightly increased under drip fertigation whereas nitrogen use efficiencies were not constant along the growing seasons. The reason for that could be lateral leaching and root proliferation into the labeled and unlabeled subplots. Field water use efficiency was highly increased for both growing seasons under drip fertigation practice. The rate of field water use efficiencies

  13. Estimation of methane emission flux at landfill surface using laser methane detector: Influence of gauge pressure.

    Science.gov (United States)

    Park, Jin-Kyu; Kang, Jong-Yun; Lee, Nam-Hoon

    2016-08-01

    The aim of this study was to investigate the possibility of measuring methane emission fluxes, using surface methane concentration and gauge pressure, by analyzing the influence of gauge pressure on the methane emission flux and the surface methane concentration, as well as the correlation between the methane emission flux and surface methane concentrations. The surface methane concentration was measured using a laser methane detector. Our results show a positive linear relationship between the surface methane concentration and the methane emission flux. Furthermore, the methane emission flux showed a positive linear relationship with the gauge pressure; this implies that when the surface methane concentration and the surface gauge pressure are measured simultaneously, the methane emission flux can be calculated using Darcy's law. A decrease in the vertical permeability was observed when the gauge pressure was increased, because reducing the vertical permeability may lead to a reduced landfill gas emission to the atmosphere, and landfill gas would be accumulated inside the landfill. Finally, this method is simple and can allow for a greater number of measurements during a relatively shorter period. Thus, it provides a better representation of the significant space and time variations in methane emission fluxes. © The Author(s) 2016.

  14. Nonlinear mean field theory for nuclear matter and surface properties

    International Nuclear Information System (INIS)

    Boguta, J.; Moszkowski, S.A.

    1983-01-01

    Nuclear matter properties are studied in a nonlinear relativistic mean field theory. We determine the parameters of the model from bulk properties of symmetric nuclear matter and a reasonable value of the effective mass. In this work, we stress the nonrelativistic limit of the theory which is essentially equivalent to a Skyrme hamiltonian, and we show that most of the results can be obtained, to a good approximation, analytically. The strength of the required parameters is determined from the binding energy and density of nuclear matter and the effective nucleon mass. For realistic values of the parameters, the nonrelativistic approximation turns out to be quite satisfactory. Using reasonable values of the parameters, we can account for other key properties of nuclei, such as the spin-orbit coupling, surface energy, and diffuseness of the nuclear surface. Also the energy dependence of the nucleon-nucleus optical model is accounted for reasonably well except near the Fermi surface. It is found, in agreement with empirical results, that the Landau parameter F 0 is quite small in normal nuclear matter. Both density dependence and momentum dependence of the NN interaction, but especially the former, are important for nuclear saturation. The required scalar and vector coupling constants agree fairly well with those obtained from analyses of NN scattering phase shifts with one-boson-exchange models. The mean field theory provides a semiquantitative justification for the weak Skyrme interaction in odd states. The strength of the required nonlinear term is roughly consistent with that derived using a new version of the chiral mean field theory in which the vector mass as well as the nucleon mass is generated by the sigma-field. (orig.)

  15. RF power absorption by plasma of low pressure low power inductive discharge located in the external magnetic field

    Science.gov (United States)

    Kralkina, E. A.; Rukhadze, A. A.; Nekliudova, P. A.; Pavlov, V. B.; Petrov, A. K.; Vavilin, K. V.

    2018-03-01

    Present paper is aimed to reveal experimentally and theoretically the influence of magnetic field strength, antenna shape, pressure, operating frequency and geometrical size of plasma sources on the ability of plasma to absorb the RF power characterized by the equivalent plasma resistance for the case of low pressure RF inductive discharge located in the external magnetic field. The distinguishing feature of the present paper is the consideration of the antennas that generate not only current but charge on the external surface of plasma sources. It is shown that in the limited plasma source two linked waves can be excited. In case of antennas generating only azimuthal current the waves can be attributed as helicon and TG waves. In the case of an antenna with the longitudinal current there is a surface charge on the side surface of the plasma source, which gives rise to a significant increase of the longitudinal and radial components of the RF electric field as compared with the case of the azimuthal antenna current.

  16. Tunable High-Pressure Field Operating on a Cationic Biphenyl Derivative Intercalated in Clay Minerals.

    Science.gov (United States)

    Tominaga, Makoto; Nishioka, Yukihiro; Tani, Seiji; Suzuki, Yasutaka; Kawamata, Jun

    2017-08-09

    We propose a methodology for applying a pseudo uniaxial pressure to an organic molecule under ordinary temperature and pressure, namely by intercalation into smectites. The pseudo pressure on a biphenyl derivative (BP) was estimated from the averaged dihedral angle around the central bond of BP. In a high hydrostatic pressure field, biphenyl takes a planar conformation. In the interlayer space of synthetic saponite (SSA), the averaged dihedral angle of BP at a loading level of 27% versus the cation exchange capacity was ~26.3°, which indicates that the pseudo pressure applied to BP in the SSA interlayer space corresponds to 0.99 GPa. The high pseudo-pressure field in the interlayer space of SSA was also confirmed by absorption measurements. The dihedral angle around the central bond of the biphenyl moiety decreased to enhance the planarity of the molecule, mainly in response to the electrostatic force that operates between the negatively charged SSA layer and the interlayer cation. The pseudo pressure operating on BP in the smectite interlayer space could be controlled by varying the smectite layer charge density and/or the BP loading level. By using this methodology, controllable pseudo high-pressure properties of organic molecules can be obtained at ordinary temperatures and pressures.

  17. Formation Mechanism of Surface Crack in Low Pressure Casting of A360 Alloy

    Science.gov (United States)

    Liu, Shan-Guang; Cao, Fu-Yang; Ying, Tao; Zhao, Xin-Yi; Liu, Jing-Shun; Shen, Hong-Xian; Guo, Shu; Sun, Jian-Fei

    2017-12-01

    A surface crack defect is normally found in low pressure castings of Al alloy with a sudden contraction structure. To further understand the formation mechanism of the defect, the mold filling process is simulated by a two-phase flow model. The experimental results indicate that the main reason for the defect deformation is the mismatching between the height of liquid surface in the mold and pressure in the crucible. In the case of filling, a sudden contraction structure with an area ratio smaller than 0.5 is obtained, and the velocity of the liquid front increases dramatically with the influence of inertia. Meanwhile, the pressurizing speed in the crucible remains unchanged, resulting in the pressure not being able to support the height of the liquid level. Then the liquid metal flows back to the crucible and forms a relatively thin layer solidification shell on the mold wall. With the increasing pressure in the crucible, the liquid level rises again, engulfing the shell and leading to a surface crack. As the filling velocity is characterized by the damping oscillations, surface cracks will form at different heights. The results shed light on designing a suitable pressurizing speed for the low pressure casting process.

  18. Analysis of the pressure fields in a swirling annular jet flow

    NARCIS (Netherlands)

    Perçin, M.; Vanierschot, M.; van Oudheusden, B.W.

    2017-01-01

    In this paper, we investigate the flow structures and pressure fields of a free annular swirling jet flow undergoing vortex breakdown. The flow field is analyzed by means of time-resolved tomographic particle image velocimetry measurements, which enable the reconstruction of the three-dimensional

  19. Effect of pressure on the crystal field splitting in rare earth pnictides and chalcogenides

    International Nuclear Information System (INIS)

    Schirber, J.E.; Weaver, H.T.

    1978-01-01

    The experimental situation for the pressure dependence of the crystal field of praseodymium pnictides and chalcogenides is reviewed and compared with the predictions of the point charge model. The problem of separating exchange and crystal field contributions from the measured NMR frequency shift or susceptibility measurements is discussed as well as problems explaining these effects with conduction electron related models

  20. All-(111) surface silicon nanowire field effect transistor devices: Effects of surface preparations

    NARCIS (Netherlands)

    Masood, M.N.; Carlen, Edwin; van den Berg, Albert

    2014-01-01

    Etching/hydrogen termination of All-(111) surface silicon nanowire field effect (SiNW-FET) devices developed by conventional photolithography and plane dependent wet etchings is studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and

  1. Support surfaces for pressure ulcer prevention: A network meta-analysis.

    Directory of Open Access Journals (Sweden)

    Chunhu Shi

    Full Text Available Pressure ulcers are a prevalent and global issue and support surfaces are widely used for preventing ulceration. However, the diversity of available support surfaces and the lack of direct comparisons in RCTs make decision-making difficult.To determine, using network meta-analysis, the relative effects of different support surfaces in reducing pressure ulcer incidence and comfort and to rank these support surfaces in order of their effectiveness.We conducted a systematic review, using a literature search up to November 2016, to identify randomised trials comparing support surfaces for pressure ulcer prevention. Two reviewers independently performed study selection, risk of bias assessment and data extraction. We grouped the support surfaces according to their characteristics and formed evidence networks using these groups. We used network meta-analysis to estimate the relative effects and effectiveness ranking of the groups for the outcomes of pressure ulcer incidence and participant comfort. GRADE was used to assess the certainty of evidence.We included 65 studies in the review. The network for assessing pressure ulcer incidence comprised evidence of low or very low certainty for most network contrasts. There was moderate-certainty evidence that powered active air surfaces and powered hybrid air surfaces probably reduce pressure ulcer incidence compared with standard hospital surfaces (risk ratios (RR 0.42, 95% confidence intervals (CI 0.29 to 0.63; 0.22, 0.07 to 0.66, respectively. The network for comfort suggested that powered active air-surfaces are probably slightly less comfortable than standard hospital mattresses (RR 0.80, 95% CI 0.69 to 0.94; moderate-certainty evidence.This is the first network meta-analysis of the effects of support surfaces for pressure ulcer prevention. Powered active air-surfaces probably reduce pressure ulcer incidence, but are probably less comfortable than standard hospital surfaces. Most prevention evidence was

  2. A variable pressure method for characterizing nanoparticle surface charge using pore sensors.

    Science.gov (United States)

    Vogel, Robert; Anderson, Will; Eldridge, James; Glossop, Ben; Willmott, Geoff

    2012-04-03

    A novel method using resistive pulse sensors for electrokinetic surface charge measurements of nanoparticles is presented. This method involves recording the particle blockade rate while the pressure applied across a pore sensor is varied. This applied pressure acts in a direction which opposes transport due to the combination of electro-osmosis, electrophoresis, and inherent pressure. The blockade rate reaches a minimum when the velocity of nanoparticles in the vicinity of the pore approaches zero, and the forces on typical nanoparticles are in equilibrium. The pressure applied at this minimum rate can be used to calculate the zeta potential of the nanoparticles. The efficacy of this variable pressure method was demonstrated for a range of carboxylated 200 nm polystyrene nanoparticles with different surface charge densities. Results were of the same order as phase analysis light scattering (PALS) measurements. Unlike PALS results, the sequence of increasing zeta potential for different particle types agreed with conductometric titration.

  3. Field measurement of local ice pressures on the ARAON in the Beaufort Sea

    Directory of Open Access Journals (Sweden)

    Lee Tak-Kee

    2014-12-01

    Full Text Available This study conducted four field measurements of local ice pressure during the icebreaking voyage of the icebreaking research vessel “ARAON” in the Chukchi and Beaufort seas from July to August of 2010. For measurements, 14 strain gauges, including 8 strain gauge rosettes, were set on the bow of the port side. Influence coefficients were determined using a finite element model of the instrumented area and they were used to convert the measured strains on the hull structure to local ice pressures. The converted maximum pressure was calculated as 2.12 MPa on an area of 0.28 m2. Pressure-area curves were developed from the surveyed pressure data and the results were compared with previously measured data. The study results are expected to provide an understanding of local ice pressures and thus be useful in the structural design of ice class ships.

  4. Field measurement of local ice pressures on the ARAON in the Beaufort Sea

    Science.gov (United States)

    Lee, Tak-Kee; Lee, Jong-Hyun; Kim, Heungsub; Rim, Chae Whan

    2014-12-01

    This study conducted four field measurements of local ice pressure during the icebreaking voyage of the icebreaking research vessel "ARAON" in the Chukchi and Beaufort seas from July to August of 2010. For measurements, 14 strain gauges, including 8 strain gauge rosettes, were set on the bow of the port side. Influence coefficients were determined using a finite element model of the instrumented area and they were used to convert the measured strains on the hull structure to local ice pressures. The converted maximum pressure was calculated as 2.12 MPa on an area of 0.28 m2. Pressure-area curves were developed from the surveyed pressure data and the results were compared with previously measured data. The study results are expected to provide an understanding of local ice pressures and thus be useful in the structural design of ice class ships.

  5. Experimental verification of the role of electron pressure in fast magnetic reconnection with a guide field

    Science.gov (United States)

    Fox, W.

    2017-10-01

    Magnetic reconnection enables explosive conversion of magnetic field energy to plasma kinetic energy in space and laboratory plasmas. In many reconnecting plasmas in space, solar, and laboratory plasmas, reconnection proceeds in the presence of a finite guide field (GF) such that the magnetic field lines meet at an angle less than 180°, and in magnetic fusion devices the guide field can be the largest component of the field. We report detailed laboratory observations of the structure of reconnection current sheets in a two-fluid plasma regime with a guide magnetic field. We observe and quantitatively analyze the quadrupolar electron pressure variation in the ion-diffusion region, as originally predicted by extended magnetohydrodynamics simulations. The projection of the electron pressure gradient parallel to the magnetic field contributes significantly to balancing the parallel electric field, and the results demonstrate how parallel and perpendicular force balance are coupled in guide field reconnection and confirm basic theoretical models of the importance of electron pressure gradients for obtaining fast magnetic reconnection. I discuss connections to observations of reconnection with finite guide field by spacecraft missions, and implications for two-fluid reconnection in magnetic fusion devices.

  6. Surface flute modes in the bumpy magnetic field

    International Nuclear Information System (INIS)

    Girka, I.O.; Girka, V.O.; Lapshin, V.I.

    2005-01-01

    Surface electromagnetic waves are often determined as the most possible cause of undesirable heating of edge plasma that leads, in turn, to strengthening of plasma - wall interaction in stellarators and increased plasma contamination. The propagation of surface flute modes near the interface of plasma column separated by a vacuum layer from the ring cylindrical ideally conductive metallic chamber is studied. The external steady bumpy magnetic field B-vector 0 = B 0z e-vector z + B 0r e-vector r was considered, B 0z =B 00 [1+ε m (r)cos(k m z)], here ε m '≡dε m /dr, k m =2π/L, L is the period of nonuniformity. non-uniformity of B-vector 0 is planned to be dominant in the confining magnetic field of the modular stellarator Helias, ε m ∼ 0.13. In the bumpy magnetic field the electromagnetic disturbance propagates in the form of the wave envelope, in which one alongside with the fundamental harmonic, proportional to exp[i(mθ±-ωt)], infinite set of satellite spatial harmonics, proportional to exp[i(mθ ± jk m z - ωt)], j=1,2,3..., is present. It is shown, that in the first approximation in the respect to ε m , amplitudes of the fundamental harmonics of the E-wave with the field components E r , E θ , B z do not vary, small satellite harmonics of these fields arise, proportional to exp[i(mθ ± k m z - ωt)]. At the same time due to weak coupling of - and - modes, caused by B-vector 0 nonuniformity and nonzero axial wave number of satellite harmonics, small satellite harmonics of H-wave with the field components E z , B r , B θ also arise. The amplitudes of satellite harmonics of E-wave are shown to be symmetric: E r (+) =E r (-) , E θ (+) =E θ (-) , B z (+) =B z (-) , and the amplitudes of H-wave are antisymmetric: B r (+) =-B r (-) , B θ (+) =- B θ (-) , E z (+) =-E z (-) . In the second approximation in the respect to ε m corrections to the amplitudes of the fundamental harmonic of E-wave arise. The correction to the eigen frequency of the wave

  7. Direct analysis of dispersive wave fields from near-field pressure measurements

    NARCIS (Netherlands)

    Horchens, L.

    2011-01-01

    Flexural waves play a significant role for the radiation of sound from plates. The analysis of flexural wave fields enables the detection of sources and transmission paths in plate-like structures. The measurement of these wave fields can be carried out indirectly by means of near-field acoustic

  8. Atmospheric pressure plasma surface modification of titanium for high temperature adhesive bonding

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.

    2011-01-01

    In this investigation surface treatment of titanium is carried out by plasma ion implantation under atmospheric pressure plasma in order to increase the adhesive bond strength. Prior to the plasma treatment, titanium surfaces were mechanically treated by sand blasting. It is observed that the

  9. Pressure effects on interfacial surface contacts and performance of organic solar cells

    NARCIS (Netherlands)

    Agyei-Tuffour, B.; Doumon, Nutifafa Y.; Rwenyagila, E. R.; Asare, J.; Oyewole, O. K.; Shen, Z.; Petoukhoff, C. E.; Zebaze Kana, M. G.; Ocarroll, D. M.; Soboyejo, W. O.

    2017-01-01

    This paper explores the effects of pressure on the interfacial surface contacts and the performance of organic solar cells. A combination of experimental techniques and analytical/computational models is used to study the evolving surface contacts profiles that occur when compliant, semi-rigid and

  10. Gapless Fermi Surfaces in anisotropic multiband superconductors in magnetic field.

    Science.gov (United States)

    Barzykin, Victor; Gor'kov, Lev P.

    2007-03-01

    We propose that a new state with a fully gapless Fermi surface appears in quasi-2D multiband superconductors in magnetic field applied parallel to the plane. It is characterized by a paramagnetic moment caused by a finite density of states on the open Fermi surface. We calculate thermodynamic and magnetic properties of the gapless state for both s-wave and d-wave cases, and discuss the details of the 1-st order metamagnetic phase transition that accompanies the appearance of the new phase in s-wave superconductors. We suggest possible experiments to detect this state both in the s-wave (2-H NbSe2) and d-wave (CeCoIn5) superconductors.

  11. Electric field measurements at near-atmospheric pressure by coherent Raman scattering of laser beams

    International Nuclear Information System (INIS)

    Ito, Tsuyohito; Kobayashi, Kazunobu; Hamaguchi, Satoshi; Mueller, Sarah; Czarnetzki, Uwe

    2010-01-01

    Electric field measurements at near-atmospheric pressure environments based on electric-field induced Raman scattering are applied to repetitively pulsed nanosecond discharges. The results have revealed that the peak electric field near the centre of the gap is almost independent of the applied voltage. Minimum sustainable voltage measurements suggests that, at each discharge pulse, charged particles that remain from the previous pulse serve as discharge seeds and play an important role for generation of uniform glow-like discharges.

  12. Analytical solution for charged fluid pressure profiles - circulation in combined electromagnetic field

    Science.gov (United States)

    Kovář, Jiří; Slaný, Petr; Stuchlík, Zdeněk; Karas, Vladimír; Trova, Audrey

    2017-12-01

    We introduce a general transformation leading to an integral form of pressure equations characterizing equilibrium configurations of charged perfect fluid circling in strong gravitational and combined electromagnetic fields. The transformation generalizes our recent analytical treatment applicable to electric or magnetic fields treated separately along with the gravitational one. As an example, we present a particular solution for a fluid circling close to a charged rotating black hole immersed in an asymptotically uniform magnetic field.

  13. Modeling and Experimental Investigation of Pressure Field in the Grinding Zone with Nanoparticle Jet of MQL

    Directory of Open Access Journals (Sweden)

    C. H. Li

    2013-01-01

    Full Text Available Solid nano particles were added in minimum quantity lubrication (MQL fluid medium to make nanofluids, that is, after the mixing and atomization of nanoparticle, lubricants and high pressure gas, to inject solid nano particle in the grinding zone with the form of jet flow. The mathematical model of two-phase flow pressure field of grinding zone with nanoparticle jet flow of MQL was established, and the simulation study was conducted. The results show that pressures in the grinding zone increased with the acceleration of grinding wheel, sharply decreased with the increased minimum clearance, and increased with the acceleration of jet flow. At three spraying angles of nozzles, when the nozzle angle was 15°, the pressure of grinding zone along the speed of grinding wheel was larger than the rest two angles. On the experimental platform built by KP-36 precision grinder and nanoparticle jet flow feed way, CY3018 pressure sensor was used to test the regularities of pressure field variations. The impact of the speed of grinding wheel, the gap between workpiece and grinding wheel, jet flow velocity, and spraying angles of nozzles on the pressure field of grinding zone was explored. The experimental result was generally consistent with the theoretical simulation, which verified the accuracy of the theoretical analysis.

  14. Pressure drop and heat transfer of lithium single-phase flow under transverse magnetic field

    International Nuclear Information System (INIS)

    Takahashi, Minoru; Aritomi, Masanori; Inoue, Akira; Matsuzaki, Mitsuo

    1996-01-01

    Pressure drop and heat transfer characteristics of a lithium single-phase flow in a rectangular channel was investigated experimentally in the presence of a magnetic field. Friction loss coefficient under non-magnetic field and skin friction coefficient under magnetic field agreed well with the Blasius formula and a simple analytical expression, respectively. Nusselt number under non-magnetic field was slightly lower than the correlation by Hartnett and Irvine. Heat transfer was enhanced by increasing magnetic field above the Hartmann number of about 200. (author)

  15. Electric field measurement in an atmospheric or higher pressure gas by coherent Raman scattering of nitrogen

    International Nuclear Information System (INIS)

    Ito, Tsuyohito; Kobayashi, Kazunobu; Hamaguchi, Satoshi; Mueller, Sarah; Luggenhoelscher, Dirk; Czarnetzki, Uwe

    2009-01-01

    The feasibility of electric field measurement based on field-induced coherent Raman scattering is demonstrated for the first time in a nitrogen containing gas at atmospheric or higher pressure, including open air. The technique is especially useful for the determination of temporal and spatial profiles of the electric field in air-based microdischarges, where nitrogen is abundant. In our current experimental setup, the minimum detectable field strength in open air is about 100 V mm -1 , which is sufficiently small compared with the average field present in typical microdischarges. No further knowledge of other gas/plasma parameters such as the nitrogen density is required. (fast track communication)

  16. Liquid Hydrogen Propellant Tank Sub-Surface Pressurization with Gaseous Helium

    Science.gov (United States)

    Stephens, J. R.; Cartagena, W.

    2015-01-01

    A series of tests were conducted to evaluate the performance of a propellant tank pressurization system with the pressurant diffuser intentionally submerged beneath the surface of the liquid. Propellant tanks and pressurization systems are typically designed with the diffuser positioned to apply pressurant gas directly into the tank ullage space when the liquid propellant is settled. Space vehicles, and potentially propellant depots, may need to conduct tank pressurization operations in micro-gravity environments where the exact location of the liquid relative to the diffuser is not well understood. If the diffuser is positioned to supply pressurant gas directly to the tank ullage space when the propellant is settled, then it may become partially or completely submerged when the liquid becomes unsettled in a microgravity environment. In such case, the pressurization system performance will be adversely affected requiring additional pressurant mass and longer pressurization times. This series of tests compares and evaluates pressurization system performance using the conventional method of supplying pressurant gas directly to the propellant tank ullage, and then supplying pressurant gas beneath the liquid surface. The pressurization tests were conducted on the Engineering Development Unit (EDU) located at Test Stand 300 at NASA Marshall Space Flight Center (MSFC). EDU is a ground based Cryogenic Fluid Management (CFM) test article supported by Glenn Research Center (GRC) and MSFC. A 150 ft3 propellant tank was filled with liquid hydrogen (LH2). The pressurization system used regulated ambient helium (GHe) as a pressurant, a variable position valve to maintain flow rate, and two identical independent pressurant diffusers. The ullage diffuser was located in the forward end of the tank and was completely exposed to the tank ullage. The submerged diffuser was located in the aft end of the tank and was completely submerged when the tank liquid level was 10% or greater

  17. Application of modern well test analysis techniques to pressure transient tests in Kizildere geothermal field, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Onur, M.; Serpen, U.; Gok, I.M. [Istanbul Technical Univ. (Turkey). Faculty of Mines; Zeybek, A.D. [Al-Mutlaq Compound, Al-Khobar (Saudi Arabia)

    2003-04-01

    The analyses of two build-up tests and one interference test in the Kizildere geothermal field, Turkey, are presented. Modern well test analysis methods based on pressure-derivative (logarithmic time rate of pressure) and non-linear regression, as well as conventional log-log and semi-log straight-line methods, have been used in the interpretation of these field pressure tests. Pressure transient models based on both homogeneous reservoirs and fractal reservoirs without matrix participation are considered in the analysis. It is shown that the use of conventional analysis methods alone can lead to an inaccurate interpretation of these field tests, and the use of modern analysis techniques in conjunction with conventional analysis techniques provides a more reliable and accurate interpretation of the well test data in the Kizildere geothermal field. The information obtained (e.g., estimates of permeability thickness and fractal dimensions) from analyses of these tests should prove useful for reservoir characterization studies in the Kizildere field, where reinjection is scheduled to begin soon. Finally, the modern interpretation methods described in this paper are recommended for analysis of well test pressure data from geothermal reservoirs. (Author)

  18. Surface-nitriding treatment of steels using microwave-induced nitrogen plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Sato, Shigeo; Arai, Yuuki; Yamashita, Noboru; Kojyo, Atsushi; Kodama, Kenji; Ohtsu, Naofumi; Okamoto, Yukio; Wagatsuma, Kazuaki

    2012-01-01

    A rapid surface-nitriding system using microwave-induced nitrogen plasma at atmospheric pressure was developed for modifying iron and steel surfaces. Since the conventional plasma nitriding technique requires a low-pressure atmosphere in the treatment chamber, the population of excited nitrogen molecules in the plasma is limited. Accordingly, several hours are required for nitriding treatment. By contrast, the developed nitriding system can use atmospheric-pressure plasma through application of the Okamoto cavity for excitation of nitrogen plasma. The high population of excited nitrogen molecules induced by the atmospheric-pressure plasma allowed the formation of a nitriding layer that was several micrometers thick within 1 min and produced an expanded austenite iron phase with a high nitrogen concentration close to the solubility limit on the iron substrate. In addition, the nitriding treatment on high-chromium steel was performed by introducing a reducing gas such as NH 3 and H 2 into the treatment chamber. While the nitriding reaction did not proceed in a simple N 2 atmosphere due to surface oxidation, the surface reduction induced by the NH 3 or H 2 gas promoted the nitriding reaction at the surface. These nitriding phenomena characteristics of the atmospheric-pressure plasma are discussed in this paper based on the effects of the specimen temperature and plasma atmosphere on the thickness, the chemical states, and the nitride compounds of the nitrided layer as investigated by X-ray diffraction, glow-discharge optical emission spectroscopy, and X-ray photoelectron spectroscopy.

  19. Influence of surface rectangular defect winding layer on burst pressure of CNG-II composite cylinder

    Science.gov (United States)

    You, H. X.; Peng, L.; Zhao, C.; Ma, K.; Zhang, S.

    2018-01-01

    To study the influence of composite materials’ surface defect on the burst pressure of CNG-II composite cylinder, the surface defect was simplified as a rectangular slot of certain size on the basis of actually investigating the shape of cylinder’s surface defect. A CNG-II composite cylinder with a rectangular slot defect (2mm in depth) was used for burst test, and the numerical simulation software ANSYS was used to calculate its burst pressure. Through comparison between the burst pressure in the test and the numerical analysis result, the correctness of the numerical analysis method was verified. On this basis, the numerical analysis method was conducted for composite cylinders with surface defect in other depth. The result showed that surface defect in the form of rectangular slot had no significant effect on the liner stress of composite cylinder. Instead, it had a great influence on the stress of fiber-wrapped layer. The burst pressure of the composite cylinder decreased as the defect depth increasing. The hoop stress at the bottom of the defect in the shape of rectangular slot exceeded the maximum of the composite materials’ tensile strength, which could result in the burst pressure of composite cylinders decreasing.

  20. Near-field and high-resolution cylindrical noise source location method based on vector sound pressure array

    Directory of Open Access Journals (Sweden)

    ZUO Xiang

    2017-08-01

    Full Text Available The existing underwater noise source near-field location method usually assumes that the measurement plane is flat, which increases the difficulty of applying the underwater noise target test for cylindrical distribution. Simultaneously, the conventional near-field focused beam has a lower spatial resolution when used to locate an underwater noise source with cylindrical distribution. Moreover, the near-field underwater noise source location method based on the sound pressure array has a left and right side fuzzy problem. In order to solve these problems, by establishing the near-field measurement model of the noise source with cylindrical distribution as the measurement surface, and combining the unilateral directivity of the vector hydrophone and the high resolution characteristics of the MUSIC algorithm, a near-field and high resolution location method is proposed for cylindrical distribution based on vector sound pressure, and a computer simulation is carried out. The results show that the method can use a smaller array aperture to locate the underwater noise source, enabling it to be used to locate and recognize the noise sources of complex and large-scale cylindrical systems.

  1. A model for description of the pressure field on a plate as the vortex ring passes

    Science.gov (United States)

    Kuibin, P. A.

    2017-11-01

    During recent experimental research a phenomenon of vortex reconnection between coils of helical-like vortex in expanding cone was revealed. Two different scenarios of the reconnection were recorded with high speed video camera. In one case a vortex ring linked with the main helical-like vortex was observed. In another case the vortex ring was found to separate from the main vortex. After separation the vortex ring moves by spiral trajectory approaching the channel wall. The subsequent experiments with synchronization of the video recording with measurements of the pressure on the channel wall revealed intense pressure pulses as the vortex ring passed near the probe. In the present work we develop an analytical model for describing the pressure pulses arising when the vortex ring passes along surface. For simplicity we consider a flat surface rather than a conical one. The performed analysis yielded the pressure distributions on the surface in dependence on the specified parameters. The most important parameter that determines the form of pressure peaks is the minimum distance from the vortex to the surface. Variation of the angles of inclination of the ring plane provides fundamentally different pulse shapes.

  2. Determining cardiac velocity fields and intraventricular pressure distribution from a sequence of ultrafast CT cardiac images.

    Science.gov (United States)

    Song, S M; Leahy, R M; Boyd, D P; Brundage, B H; Napel, S

    1994-01-01

    A method of computing the velocity field and pressure distribution from a sequence of ultrafast CT (UFCT) cardiac images is demonstrated. UFCT multi-slice cine imaging gives a series of tomographic slices covering the volume of the heart at a rate of 17 frames per second. The complete volume data set can be modeled using equations of continuum theory and through regularization, velocity vectors of both blood and tissue can be determined at each voxel in the volume. The authors present a technique to determine the pressure distribution throughout the volume of the left ventricle using the computed velocity field. A numerical algorithm is developed by discretizing the pressure Poisson equation (PPE), which Is based on the Navier-Stokes equation. The algorithm is evaluated using a mathematical phantom of known velocity and pressure-Couette flow. It is shown that the algorithm based on the PPE can reconstruct the pressure distribution using only the velocity data. Furthermore, the PPE is shown to be robust in the presence of noise. The velocity field and pressure distribution derived from a UFCT study of a patient are also presented.

  3. Calculation of acoustic field based on laser-measured vibration velocities on ultrasonic transducer surface

    Science.gov (United States)

    Hu, Liang; Zhao, Nannan; Gao, Zhijian; Mao, Kai; Chen, Wenyu; Fu, Xin

    2018-05-01

    Determination of the distribution of a generated acoustic field is valuable for studying ultrasonic transducers, including providing the guidance for transducer design and the basis for analyzing their performance, etc. A method calculating the acoustic field based on laser-measured vibration velocities on the ultrasonic transducer surface is proposed in this paper. Without knowing the inner structure of the transducer, the acoustic field outside it can be calculated by solving the governing partial differential equation (PDE) of the field based on the specified boundary conditions (BCs). In our study, the BC on the transducer surface, i.e. the distribution of the vibration velocity on the surface, is accurately determined by laser scanning measurement of discrete points and follows a data fitting computation. In addition, to ensure the calculation accuracy for the whole field even in an inhomogeneous medium, a finite element method is used to solve the governing PDE based on the mixed BCs, including the discretely measured velocity data and other specified BCs. The method is firstly validated on numerical piezoelectric transducer models. The acoustic pressure distributions generated by a transducer operating in an homogeneous and inhomogeneous medium, respectively, are both calculated by the proposed method and compared with the results from other existing methods. Then, the method is further experimentally validated with two actual ultrasonic transducers used for flow measurement in our lab. The amplitude change of the output voltage signal from the receiver transducer due to changing the relative position of the two transducers is calculated by the proposed method and compared with the experimental data. This method can also provide the basis for complex multi-physical coupling computations where the effect of the acoustic field should be taken into account.

  4. Electric field effects on the dynamics of bubble detachment from an inclined surface

    International Nuclear Information System (INIS)

    Di Marco, P; Morganti, N; Saccone, G

    2015-01-01

    An experimental apparatus to study bubble detachment from an inclined surface under the action of electric forces is described. It consists of a container filled with FC72 at room temperature and pressure where a train of gas bubbles is injected from an orifice. An electrostatic field can be imposed around the bubble, while the cell can be tilted from 0 to 90°. It is possible to study interface growth with the aid of high-speed cinematography. Since the interface is asymmetrical, a mirror system allowed to acquire, in the same frame, two images at 90° of the bubble. Different inclinations, injection rates and voltages were tested in order to couple the effects of shear gravity and electric field. Curvature and contact angles have been derived with appropriate interpolation methods of the profile. Force balances on the bubble were checked, finding an electric force, which, at first pulls the bubbles from the orifice, then pushes it against the surface. The motion of the center of gravity confirms this behaviour. A power balance has been developed to determine the energy contributions, revealing that surface growth incorporates both the effects of inlet power and electric field. (paper)

  5. Crystal fields of Pr sup 3 sup + in LiYF sub 4 under pressure

    CERN Document Server

    Tröster, T

    2003-01-01

    Fluorescence spectra of LiYF sub 4 :Pr sup 3 sup + have been measured between 12,000 and 22,000 cm sup - sup 1 under pressures up to 10 GPa. In total, 25 crystal field energy levels were obtained and used for the determination of free-ion and crystal field parameters under pressure. According to the nephelauxetic effect, the free-ion parameters decrease with increasing pressure. The relative decrease is larger for the Slater than for the spin-orbit coupling parameter. This behavior is consistent with former studies on Pr sup 3 sup + in different crystals and can be explained by a special covalency model. According to an effective D sub 2 sub d symmetry, five crystal field parameters B sub 0 sup 2 (f,f), B sub 0 sup 4 (f,f), B sub 4 sup 4 (f,f), B sub 0 sup 6 (f,f), and B sub 4 sup 6 (f,f) are non-zero. The pressure-induced changes of these parameters have been determined up to the maximum pressure of 10 GPa. In order to improve the calculation of the crystal field levels, the configuration interactions with t...

  6. Pressure controlled transition into a self-induced topological superconducting surface state

    KAUST Repository

    Zhu, Zhiyong

    2014-02-07

    Ab-initio calculations show a pressure induced trivial-nontrivial-trivial topological phase transition in the normal state of 1T-TiSe2. The pressure range in which the nontrivial phase emerges overlaps with that of the superconducting ground state. Thus, topological superconductivity can be induced in protected surface states by the proximity effect of superconducting bulk states. This kind of self-induced topological surface superconductivity is promising for a realization of Majorana fermions due to the absence of lattice and chemical potential mismatches. For appropriate electron doping, the formation of the topological superconducting surface state in 1T-TiSe 2 becomes accessible to experiments as it can be controlled by pressure.

  7. Imaging near-surface heterogeneities by natural migration of backscattered surface waves: Field data test

    KAUST Repository

    Liu, Zhaolun

    2017-03-06

    We have developed a methodology for detecting the presence of near-surface heterogeneities by naturally migrating backscattered surface waves in controlled-source data. The near-surface heterogeneities must be located within a depth of approximately one-third the dominant wavelength λ of the strong surface-wave arrivals. This natural migration method does not require knowledge of the near-surface phase-velocity distribution because it uses the recorded data to approximate the Green’s functions for migration. Prior to migration, the backscattered data are separated from the original records, and the band-passed filtered data are migrated to give an estimate of the migration image at a depth of approximately one-third λ. Each band-passed data set gives a migration image at a different depth. Results with synthetic data and field data recorded over known faults validate the effectiveness of this method. Migrating the surface waves in recorded 2D and 3D data sets accurately reveals the locations of known faults. The limitation of this method is that it requires a dense array of receivers with a geophone interval less than approximately one-half λ.

  8. Effects of Oxygen Partial Pressure on the Surface Tension of Liquid Nickel

    Science.gov (United States)

    SanSoucie, Michael P.; Rogers, Jan R.; Gowda, Vijaya Kumar Malahalli Shankare; Rodriguez, Justin; Matson, Douglas M.

    2015-01-01

    The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has been recently upgraded with an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled, theoretically in the range from 10-36 to 100 bar. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte, which is yttria-stabilized zirconia. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, PID-based current loop, and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects of oxygen partial pressure on the surface tension of undercooled liquid nickel will be analyzed, and the results will be presented. The surface tension will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension will be measured using the oscillating drop method. While undercooled, each sample will be oscillated several times consecutively to investigate how the surface tension behaves with time while at a particular oxygen partial pressure.

  9. Atomistic modeling of metal surfaces under electric fields: direct coupling of electric fields to a molecular dynamics algorithm

    CERN Document Server

    Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai

    2011-01-01

    The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...

  10. Effects of external fields, dimension and pressure on the electromagnetically induced transparency of quantum dots

    International Nuclear Information System (INIS)

    Vaseghi, B.; Mohebi, N.

    2013-01-01

    Effects of external electric and magnetic fields, dimension and pressure on the electromagnetically induced transparency of a pumped-probe GaAs quantum dot are investigated. To study the electromagnetically induced transparency, the probe absorption and group velocity along with refractive index of the medium are discussed. It is found that electromagnetically induced transparency occurs in the system and its frequency, transparency window and group velocity of the probe field strongly depend on the external fields, pressure and the dot size. Significant effects of external factors on the quantum dot structures have the potential applications for implementation of electromagnetically induce transparency, slow lights, optical switches and quantum information storages. - Highlights: ► Sub-band energy states of a spherical QD are used to study the EIT. ► EIT strongly depends on the external fields, dimension and pressure. ► GI of a pulse strongly depends on the external fields, dimension and pressure. ► The production and controlling EIT and GI in QDs can be used for real applications.

  11. Evaluation of unsteady pressure fields and forces in rotating airfoils from time-resolved PIV

    Science.gov (United States)

    Villegas, A.; Diez, F. J.

    2014-04-01

    The instantaneous pressure fields and aerodynamic loads are obtained for rotating airfoils from time-resolved particle image velocimetry (TR-PIV) measurements. These allowed evaluating the contribution from the local acceleration (unsteady acceleration) to the instantaneous forces. Traditionally, this term has been neglected for wind turbines with quasi-steady flows, but results show that it is a dominant term in the wake where high temporal variations in the flow field are present due to vortex shedding. Briefly, time-resolved particle image velocimetry TR-PIV measurements are used to calculate flow velocity fields and corresponding spatial and temporal derivatives. These derivatives are then used in the Poisson equation to solve for the pressure field and later used in the integral momentum equation to solve for the instantaneous forces. The robustness of the measurements is analyzed by calculating the PIV uncertainty and the independence of the calculated forces. The experimental mean aerodynamic forces are compared with theoretical predictions from the blade element momentum theory showing good agreement. The instantaneous pressure field showed dependence with time in the wake due to vortex shedding. The contribution to the instantaneous forces from each term in the integral momentum equation is evaluated. The analysis shows that the larger contributions to the normal force coefficient are from the unsteady and the pressure terms, and the larger contribution to the tangential force coefficient is from the convective term.

  12. Effect of an end plate on surface pressure distributions of two swept wings

    Directory of Open Access Journals (Sweden)

    Mohammad Reza SOLTANI

    2017-10-01

    Full Text Available A series of wind tunnel tests was conducted to examine how an end plate affects the pressure distributions of two wings with leading edge (LE sweep angles of 23° and 40°. All the experiments were carried out at a midchord Reynolds number of 8×105, covering an angle of attack (AOA range from −2° to 14°. Static pressure distribution measurements were acquired over the upper surfaces of the wings along three chordwise rows and one spanwise direction at the wing quarter-chord line. The results of the tests confirm that at a particular AOA, increasing the sweep angle causes a noticeable decrease in the upper-surface suction pressure. Furthermore, as the sweep angle increases, the development of a laminar separation bubble near the LEs of the wings takes place at higher AOAs. On the other hand, spanwise pressure measurements show that increasing the wing sweep angle results in forming a stronger vortex on the quarter-chord line which has lower sensitivity to AOA variation and remains substantially attached to the wing surface for higher AOAs than that can be achieved in the case of a lower sweep angle. In addition, data obtained indicate that installing an end plate further reinforces the spanwise flow over the wing surface, thus affecting the pressure distribution.

  13. Does Pressure Accentuate General Relativistic Gravitational Collapse and Formation of Trapped Surfaces?

    Science.gov (United States)

    Mitra, Abhas

    2013-04-01

    It is widely believed that though pressure resists gravitational collapse in Newtonian gravity, it aids the same in general relativity (GR) so that GR collapse should eventually be similar to the monotonous free fall case. But we show that, even in the context of radiationless adiabatic collapse of a perfect fluid, pressure tends to resist GR collapse in a manner which is more pronounced than the corresponding Newtonian case and formation of trapped surfaces is inhibited. In fact there are many works which show such collapse to rebound or become oscillatory implying a tug of war between attractive gravity and repulsive pressure gradient. Furthermore, for an imperfect fluid, the resistive effect of pressure could be significant due to likely dramatic increase of tangential pressure beyond the "photon sphere." Indeed, with inclusion of tangential pressure, in principle, there can be static objects with surface gravitational redshift z → ∞. Therefore, pressure can certainly oppose gravitational contraction in GR in a significant manner in contradiction to the idea of Roger Penrose that GR continued collapse must be unstoppable.

  14. Pore Pressure and Field stress variation from Salt Water Injection; A case Study from Beaver Lodge Field in Williston Basin

    Science.gov (United States)

    Mohammed, R. A.; Khatibi, S.

    2017-12-01

    One of the major concerns in producing from oil and gas reservoirs in North American Basins is the disposal of high salinity salt water. It is a misconception that Hydro frack triggers Earthquakes, but due to the high salinity and density of water being pumped to the formation that has pore space of the rock already filled, which is not the case in Hydro-frack or Enhanced Oil Recovery in which fracturing fluid is pumped into empty pore space of rocks in depleted reservoirs. A review on the Bakken history showed that the concerns related to induce seismicity has increased over time due to variations in Pore pressure and In-situ stress that have shown steep changes in the region over the time. In this study, we focused on Pore pressure and field Stress variations in lower Cretaceous Inyan Kara and Mississippian Devonian Bakken, Inyan Kara is the major source for class-II salt-water disposal in the basin. Salt-water disposal is the major cause for induced seismicity. A full field study was done on Beaver Lodge Field, which has many salt-water disposal wells Adjacent to Oil and Gas Wells. We analyzed formation properties, stresses, pore-pressure, and fracture gradient profile in the field and. The constructed Mechanical Earth Model (MEM) revealed changes in pore pressure and stresses over time due to saltwater injection. Well drilled in the past were compared to recently drilled wells, which showed much stress variations. Safe mud weight Window of wells near proximity of injection wells was examined which showed many cases of wellbore instabilities. Results of this study will have tremendous impact in studying environmental issues and the future drilling and Fracking operations.

  15. Use of Atmospheric-Pressure Plasma Jet for Polymer Surface Modification: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-16

    Atmospheric-pressure plasma jets (APPJs) are playing an increasingly important role in materials processing procedures. Plasma treatment is a useful tool to modify surface properties of materials, especially polymers. Plasma reacts with polymer surfaces in numerous ways thus the type of process gas and plasma conditions must be explored for chosen substrates and materials to maximize desired properties. This report discusses plasma treatments and looks further into atmospheric-pressure plasma jets and the effects of gases and plasma conditions. Following the short literature review, a general overview of the future work and research at Los Alamos National Laboratory (LANL) is discussed.

  16. Effects of radiation pressure on the equipotential surfaces in x-ray binaries

    International Nuclear Information System (INIS)

    Kondo, Y.; McCluskey, G.E. Jr.; Gulden, S.L.

    1976-01-01

    Equipotential surfaces incorporating the effect of radiation pressure were computed for the x-ray binaries Cen X-3, Cyg X-1 = HDE 226868, Vela XR-1 = 3U 0900-40 = HD 77581, and 3U 1700-37 = HD 153919. The topology of the equipotential surfaces is significantly affected by radiation pressure. In particular, the so-called critical Roche (Jacobian) lobes, the traditional figure 8's, do not exist. The effects of these results on modeling x-ray binaries are discussed

  17. Electric field measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond electric field induced second harmonic generation

    Science.gov (United States)

    Goldberg, Benjamin M.; Chng, Tat Loon; Dogariu, Arthur; Miles, Richard B.

    2018-02-01

    We present an optical electric field measurement method for use in high pressure plasma discharges. The method is based upon the field induced second harmonic generation technique and can be used for localized electric field measurements with sub-nanosecond resolution in any gaseous species. When an external electric field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the electric field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the electric field is strong enough to exceed the breakdown threshold, the measured field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.

  18. Planar time-resolved PIV for velocity and pressure retrieval in atmospheric boundary layer over surface waves.

    Science.gov (United States)

    Troitskaya, Yuliya; Kandaurov, Alexander; Sergeev, Daniil; Bopp, Maximilian; Caulliez, Guillemette

    2017-04-01

    Air-sea coupling in general is important for weather, climate, fluxes. Wind wave source is crucially important for surface waves' modeling. But the wind-wave growth rate is strongly uncertain. Using direct measurements of pressure by wave-following Elliott probe [1] showed, weak and indefinite dependence of wind-wave growth rate on the wave steepness, while Grare et.al. [2] discuss the limitations of direct measurements of pressure associated with the inability to measure the pressure close to the surface by contact methods. Recently non-invasive methods for determining the pressure on the basis of technology of time-resolved PIV are actively developed [3]. Retrieving air flow velocities by 2D PIV techniques was started from Reul et al [4]. The first attempt for retrieving wind pressure field of waves in the laboratory tank from the time-resolved PIV measurements was done in [5]. The experiments were performed at the Large Air-Sea Interaction Facility (LASIF) - MIO/Luminy (length 40 m, cross section of air channel 3.2 x 1.6 m). For 18 regimes with wind speed up to 14 m/s including presence of puddle waves, a combination of time resolved PIV technique and optical measurements of water surface form was applied to detailed investigation of the characteristics of the wind flow over the water surface. Ammonium chloride smoke was used for flow visualization illuminated by two 6 Wt blue diode lasers combined into a vertical laser plane. Particle movement was captured with high-speed camera using Scheimpflug technique (up to 20 kHz frame rate with 4-frame bursts, spatial resolution about 190 μm, field of view 314x12 mm). Velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave form. The resulting time resolved instantaneous velocity fields on regular grid allowed us to obtain momentum fluxes directly from measured air velocity fluctuations. The average wind velocity patterns were

  19. Equilibrium configurations of the conducting liquid surface in a nonuniform electric field

    Science.gov (United States)

    Zubarev, N. M.; Zubareva, O. V.

    2011-01-01

    Possible equilibrium configurations of the free surface of a conducting liquid deformed by a nonuniform external electric field are investigated. The liquid rests on an electrode that has the shape of a dihedral angle formed by two intersecting equipotential half-planes (conducting wedge). It is assumed that the problem has plane symmetry: the surface is invariant under shift along the edge of the dihedral angle. A one-parametric family of exact solutions for the shape of the surface is found in which the opening angle of the region above the wedge serves as a parameter. The solutions are valid when the pressure difference between the inside and outside of the liquid is zero. For an arbitrary pressure difference, approximate solutions to the problem are constructed and it is demonstrated the approximation error is small. It is found that, when the potential difference exceeds a certain threshold value, equilibrium solutions are absent. In this case, the region occupied by the liquid disintegrates, the disintegration scenario depending on the opening angle.

  20. Phase Field Theory and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic

    Directory of Open Access Journals (Sweden)

    John D. Clayton

    2014-07-01

    Full Text Available A nonlinear continuum phase field theory is developed to describe amorphization of crystalline elastic solids under shear and/or pressure loading. An order parameter describes the local degree of crystallinity. Elastic coefficients can depend on the order parameter, inelastic volume change may accompany the transition from crystal to amorphous phase, and transitional regions parallel to bands of amorphous material are penalized by interfacial surface energy. Analytical and simple numerical solutions are obtained for an idealized isotropic version of the general theory, for an element of material subjected to compressive and/or shear loading. Solutions compare favorably with experimental evidence and atomic simulations of amorphization in boron carbide, demonstrating the tendency for structural collapse and strength loss with increasing shear deformation and superposed pressure.

  1. Dynamic modeling method of the bolted joint with uneven distribution of joint surface pressure

    Science.gov (United States)

    Li, Shichao; Gao, Hongli; Liu, Qi; Liu, Bokai

    2018-03-01

    The dynamic characteristics of the bolted joints have a significant influence on the dynamic characteristics of the machine tool. Therefore, establishing a reasonable bolted joint dynamics model is helpful to improve the accuracy of machine tool dynamics model. Because the pressure distribution on the joint surface is uneven under the concentrated force of bolts, a dynamic modeling method based on the uneven pressure distribution of the joint surface is presented in this paper to improve the dynamic modeling accuracy of the machine tool. The analytic formulas between the normal, tangential stiffness per unit area and the surface pressure on the joint surface can be deduced based on the Hertz contact theory, and the pressure distribution on the joint surface can be obtained by the finite element software. Futhermore, the normal and tangential stiffness distribution on the joint surface can be obtained by the analytic formula and the pressure distribution on the joint surface, and assigning it into the finite element model of the joint. Qualitatively compared the theoretical mode shapes and the experimental mode shapes, as well as quantitatively compared the theoretical modal frequencies and the experimental modal frequencies. The comparison results show that the relative error between the first four-order theoretical modal frequencies and the first four-order experimental modal frequencies is 0.2% to 4.2%. Besides, the first four-order theoretical mode shapes and the first four-order experimental mode shapes are similar and one-to-one correspondence. Therefore, the validity of the theoretical model is verified. The dynamic modeling method proposed in this paper can provide a theoretical basis for the accurate dynamic modeling of the bolted joint in machine tools.

  2. INTERACTION OF IMPULSE ELECTROMAGNETIC FIELDS WITH SURFACES OF METAL SAMPLES

    Directory of Open Access Journals (Sweden)

    V. V. Pavliouchenko

    2006-01-01

    Full Text Available Measurements of maximum tangential component of magnetic intensity Hτm have been carried out in the paper. The measurements have been taken on the surface of metal samples according to time of single current pulse rise in the form of semi-sinusoid of a linear current wire. Measurements have been made with the purpose to determine a value of the component according to thickness of samples made of aluminium.Temporary resolution ranges of electric and magnetic properties and defects of sample continuity along the depth have been found.Empirical formulae of dependence Hτm on sample thickness have been derived and their relation with efficient depth penetration of magnetic field into metal has been found.

  3. Simulation and Optimization of Silicon Solar Cell Back Surface Field

    Directory of Open Access Journals (Sweden)

    Souad TOBBECHE

    2015-11-01

    Full Text Available In this paper, TCAD Silvaco (Technology Computer Aided Design software has been used to study the Back Surface Field (BSF effect of a p+ silicon layer for a n+pp+ silicon solar cell. To study this effect, the J-V characteristics and the external quantum efficiency (EQE are simulated under AM 1.5 illumination for two types of cells. The first solar cell is without BSF (n+p structure while the second one is with BSF (n+pp+ structure. The creation of the BSF on the rear face of the cell results in efficiency h of up to 16.06% with a short-circuit current density Jsc = 30.54 mA/cm2, an open-circuit voltage Voc = 0.631 V, a fill factor FF = 0.832 and a clear improvement of the spectral response obtained in the long wavelengths range. An electric field and a barrier of potential are created by the BSF and located at the junction p+/p with a maximum of 5800 V/cm and 0.15 V, respectively. The optimization of the BSF layer shows that the cell performance improves with the p+ thickness between 0.35 – 0.39 µm, the p+ doping dose is about 2 × 1014 cm-2, the maximum efficiency up to 16.19 %. The cell efficiency is more sensitive to the value of the back surface recombination velocity above a value of 103 cm/s in n+p than n+pp+ solar cell.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9565

  4. Parameters of the center of pressure displacement on the saddle during hippotherapy on different surfaces

    Directory of Open Access Journals (Sweden)

    Fabiana M. Flores

    2015-06-01

    Full Text Available Background: Hippotherapy uses horseback riding movements for therapeutic purposes. In addition to the horse's movement, the choice of equipment and types of floor are also useful in the intervention. The quantification of dynamic parameters that define the interaction of the surface of contact between horse and rider provides insight into how the type of floor surface variations act upon the subject's postural control. Objective: To test whether different types of surfaces promote changes in the amplitude (ACOP and velocity (VCOP of the center of pressure (COP displacement during the rider's contact with the saddle on the horse's back. Method: Twenty two healthy adult male subjects with experience in riding were evaluated. The penetration resistances of asphalt, sand and grass surfaces were measured. The COP data were collected on the three surfaces using a pressure measurement mat. Results: ACOP values were higher in sand, followed by grass and asphalt, with significant differences between sand and asphalt (anteroposterior, p=0.042; mediolateral, p=0.019. The ACOP and VCOP values were higher in the anteroposterior than in the mediolateral direction on all surfaces (ACOP, p=0.001; VCOP, p=0.006. The VCOP did not differ between the surfaces. Conclusion: Postural control, measured by the COP displacement, undergoes variations in its amplitude as a result of the type of floor surface. Therefore, these results reinforce the importance of the choice of floor surface when defining the strategy to be used during hippotherapy intervention.

  5. Parameters of the center of pressure displacement on the saddle during hippotherapy on different surfaces.

    Science.gov (United States)

    Flores, Fabiana M; Dagnese, Frederico; Mota, Carlos B; Copetti, Fernando

    2015-01-01

    Hippotherapy uses horseback riding movements for therapeutic purposes. In addition to the horse's movement, the choice of equipment and types of floor are also useful in the intervention. The quantification of dynamic parameters that define the interaction of the surface of contact between horse and rider provides insight into how the type of floor surface variations act upon the subject's postural control. To test whether different types of surfaces promote changes in the amplitude (ACOP) and velocity (VCOP) of the center of pressure (COP) displacement during the rider's contact with the saddle on the horse's back. Twenty two healthy adult male subjects with experience in riding were evaluated. The penetration resistances of asphalt, sand and grass surfaces were measured. The COP data were collected on the three surfaces using a pressure measurement mat. ACOP values were higher in sand, followed by grass and asphalt, with significant differences between sand and asphalt (anteroposterior, p=0.042; mediolateral, p=0.019). The ACOP and VCOP values were higher in the anteroposterior than in the mediolateral direction on all surfaces (ACOP, p=0.001; VCOP, p=0.006). The VCOP did not differ between the surfaces. Postural control, measured by the COP displacement, undergoes variations in its amplitude as a result of the type of floor surface. Therefore, these results reinforce the importance of the choice of floor surface when defining the strategy to be used during hippotherapy intervention.

  6. Calculated Fermi surface properties of LaSn3 and YSn3 under pressure

    International Nuclear Information System (INIS)

    Kanchana, V.

    2012-01-01

    The electronic structure, Fermi surface and elastic properties of the iso-structural and iso-electronic LaSn 3 and YSn 3 intermetallic compounds are studied under pressure within the frame work of density functional theory including spin-orbit coupling. The LaSn 3 Fermi surface consists of two sheets, of which the second is very complex. Under pressure a third sheet appears around compression V/V 0 =0.94, while a small topology changes in the second sheet is seen at compression V/V 0 =0.90. This may be in accordance with the anomalous behavior in the superconducting transition temperature observed in LaSn 3 , which has been suggested to reflect a Fermi surface topological transition, along with a non-monotonic pressure dependence of the density of states at the Fermi level. The similar behavior is not observed in YSn 3 for which the Fermi surface includes three sheets already at ambient conditions, and the topology remains unchanged under pressure. The reason for the difference in behavior between LaSn 3 and YSn 3 is the role of spin-orbit coupling and the hybridization of La-4f state with the Sn-p state in the vicinity of the Fermi level, which is well explained using the band structure calculation. The elastic constants and related mechanical properties are calculated at ambient as well as at elevated pressures. The elastic constants increase with pressure for both compounds and satisfy the conditions for mechanical stability under pressure. (author)

  7. Irreversible particle motion in surfactant-laden interfaces due to pressure-dependent surface viscosity

    Science.gov (United States)

    Manikantan, Harishankar; Squires, Todd M.

    2017-09-01

    The surface shear viscosity of an insoluble surfactant monolayer often depends strongly on its surface pressure. Here, we show that a particle moving within a bounded monolayer breaks the kinematic reversibility of low-Reynolds-number flows. The Lorentz reciprocal theorem allows such irreversibilities to be computed without solving the full nonlinear equations, giving the leading-order contribution of surface pressure-dependent surface viscosity. In particular, we show that a disc translating or rotating near an interfacial boundary experiences a force in the direction perpendicular to that boundary. In unbounded monolayers, coupled modes of motion can also lead to non-intuitive trajectories, which we illustrate using an interfacial analogue of the Magnus effect. This perturbative approach can be extended to more complex geometries, and to two-dimensional suspensions more generally.

  8. Surface energy-tunable iso decyl acrylate based molds for low pressure-nanoimprint lithography

    Science.gov (United States)

    Tak, Hyowon; Tahk, Dongha; Jeong, Chanho; Lee, Sori; Kim, Tae-il

    2017-10-01

    We presented surface energy-tunable nanoscale molds for unconventional lithography. The mold is highly robust, transparent, has a minimized haze, does not contain additives, and is a non-fluorinated isodecyl acrylate and trimethylolpropane triacrylate based polymer. By changing the mixing ratio of the polymer components, the cross-linking density, mechanical modulus, and surface energy (crucial factors in low pressure ((1-2) × 105 N m-2) low pressure-nanoimprint lithography (LP-NIL)), can be controlled. To verify these properties of the molds, we also characterized the surface energy by measuring the contact angles and calculating the work of adhesion among the wafer, polymer film, and mold for successful demolding in nanoscale structures. Moreover, the molds showed high optical clarity and precisely tunable mechanical and surface properties, capable of replicating sub-100 nm patterns by thermal LP-NIL and UV-NIL.

  9. Investigation of surface porosity measurements and compaction pressure as means to ensure consistent contact angle determinations

    DEFF Research Database (Denmark)

    Holm, René; Borkenfelt, Simon; Allesø, Morten

    2016-01-01

    for a compound is determined by its contact angle to a liquid, which in the present study was measured using the sessile drop method applied to a disc compact of the compound. Precise determination of the contact angle is important should it be used to either rank compounds or selected excipients to e.......g. increase the wetting from a solid dosage form. Since surface roughness of the compact has been suggested to influence the measurement this study investigated if the surface quality, in terms of surface porosity, had an influence on the measured contact angle. A correlation to surface porosity was observed......, however for six out of seven compounds similar results were obtained by applying a standard pressure (866MPa) to the discs in their preparation. The data presented in the present work therefore suggest that a constant high pressure should be sufficient for most compounds when determining the contact angle...

  10. Sequential least-square reconstruction of instantaneous pressure field around a body from TR-PIV

    Science.gov (United States)

    Jeon, Young Jin; Gomit, G.; Earl, T.; Chatellier, L.; David, L.

    2018-02-01

    A procedure is introduced to obtain an instantaneous pressure field around a wing from time-resolved particle image velocimetry (TR-PIV) and particle image accelerometry (PIA). The instantaneous fields of velocity and material acceleration are provided by the recently introduced multi-frame PIV method, fluid trajectory evaluation based on ensemble-averaged cross-correlation (FTEE). The integration domain is divided into several subdomains in accordance with the local reliability. The near-edge and near-body regions are determined based on the recorded image of the wing. The instantaneous wake region is assigned by a combination of a self-defined criterion and binary morphological processes. The pressure is reconstructed from a minimization process of the difference between measured and reconstructed pressure gradients in a least-square sense. This is solved sequentially according to a decreasing order of reliability of each subdomain to prevent a propagation of error from the less reliable near-body region to the free-stream. The present procedure is numerically assessed by synthetically generated 2D particle images based on a numerical simulation. Volumetric pressure fields are then evaluated from tomographic TR-PIV of a flow around a 30-degree-inclined NACA0015 airfoil. A possibility of using a different scheme to evaluate material acceleration for a specific subdomain is presented. Moreover, this 3D application allows the investigation of the effect of the third component of the pressure gradient by which the wake region seems to be affected.

  11. Reconstruction of an acoustic pressure field in a resonance tube by particle image velocimetry.

    Science.gov (United States)

    Kuzuu, K; Hasegawa, S

    2015-11-01

    A technique for estimating an acoustic field in a resonance tube is suggested. The estimation of an acoustic field in a resonance tube is important for the development of the thermoacoustic engine, and can be conducted employing two sensors to measure pressure. While this measurement technique is known as the two-sensor method, care needs to be taken with the location of pressure sensors when conducting pressure measurements. In the present study, particle image velocimetry (PIV) is employed instead of a pressure measurement by a sensor, and two-dimensional velocity vector images are extracted as sequential data from only a one- time recording made by a video camera of PIV. The spatial velocity amplitude is obtained from those images, and a pressure distribution is calculated from velocity amplitudes at two points by extending the equations derived for the two-sensor method. By means of this method, problems relating to the locations and calibrations of multiple pressure sensors are avoided. Furthermore, to verify the accuracy of the present method, the experiments are conducted employing the conventional two-sensor method and laser Doppler velocimetry (LDV). Then, results by the proposed method are compared with those obtained with the two-sensor method and LDV.

  12. Influence of fuel loading on neutron field in WWER-440 reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Stacho, M.; Slugen, V.; Farkas, G.; Sojak, S. [Department of Nuclear Physics and Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)

    2010-07-01

    One of the limiting factors in terms of nuclear power plant lifetime is reactor pressure vessel neutron load. Neutron embrittlement as the most important ageing effect on the reactor pressure vessel is mainly caused by fast neutron spectra. The work is focused on mapping of neutron fields in the reactor pressure vessel of WWER-440/V-213 reactor using MCNP5 transport code. The calculation of neutron fields was performed using detailed full-core MCNP model of WWER-440 reactor developed at our department. Analysis of fuel loading pattern and burn-up influence on neutron flux density distribution in the reactor pressure vessel was realized. The fuel composition corresponds to fuel cycles of Bohunice and Mochovce nuclear power plants. The goal of this work was to improve the assessment of WWER-440 reactor pressure vessel radiation degradation and following evaluation possibility of its lifetime extension and comparison of neutron flux and neutron spectra in the most loaded place of reactor pressure vessel and surveillance specimen area. (authors)

  13. Mapping gullies, dunes, lava fields, and landslides via surface roughness

    Science.gov (United States)

    Korzeniowska, Karolina; Pfeifer, Norbert; Landtwing, Stephan

    2018-01-01

    Gully erosion is a widespread and significant process involved in soil and land degradation. Mapping gullies helps to quantify past, and anticipate future, soil losses. Digital terrain models offer promising data for automatically detecting and mapping gullies especially in vegetated areas, although methods vary widely measures of local terrain roughness are the most varied and debated among these methods. Rarely do studies test the performance of roughness metrics for mapping gullies, limiting their applicability to small training areas. To this end, we systematically explored how local terrain roughness derived from high-resolution Light Detection And Ranging (LiDAR) data can aid in the unsupervised detection of gullies over a large area. We also tested expanding this method for other landforms diagnostic of similarly abrupt land-surface changes, including lava fields, dunes, and landslides, as well as investigating the influence of different roughness thresholds, resolutions of kernels, and input data resolution, and comparing our method with previously published roughness algorithms. Our results show that total curvature is a suitable metric for recognising analysed gullies and lava fields from LiDAR data, with comparable success to that of more sophisticated roughness metrics. Tested dunes or landslides remain difficult to distinguish from the surrounding landscape, partly because they are not easily defined in terms of their topographic signature.

  14. Predation pressure in Ugandan cotton fields measured by a sentinel prey method

    DEFF Research Database (Denmark)

    Howe, Andrew Gordon; Nachman, Gösta; Lövei, Gábor L.

    2015-01-01

    Pest suppression by natural enemies is an important ecosystem service, which is a valuable resource to poor smallholders in developing countries. Diverse natural enemy assemblages of arthropod predators and parasitoids are documented in various regions in Africa, but our knowledge of their impact...... on herbivores in agroecosystems remains limited. We conducted experiments in cotton, Gossypium hirsutum L. (Malvaceae), under typical local agronomic practices in Uganda to assess levels of predation pressure ascribed to natural enemies. We measured predation rates on artificial caterpillars made of plasticine...... glued to cotton plants. Predation pressure on cotton fields varied between 1.96 and 4.1% per day, but was not significantly influenced by cotton treatments (insecticide/no insecticide, monocropping/intercropping with Phaseolus spp.). Predation pressure in non-crop habitats adjacent to cotton fields...

  15. A Direct inverse model to determine permeability fields from pressure and flow rate measurements

    NARCIS (Netherlands)

    Brouwer, G.K.; Fokker, P.A.; Wilschut, F.; Zijl, W.

    2008-01-01

    The determination of the permeability field from pressure and flow rate measurements in wells is a key problem in reservoir engineering. This paper presents a Double Constraint method for inverse modeling that is an example of direct inverse modeling. The method is used with a standard

  16. A sound field separation technique based on measurements with pressure-velocity probes

    DEFF Research Database (Denmark)

    Zhang, Yong-Bin; Chen, Xin-Zhao; Jacobsen, Finn

    2009-01-01

    It has recently been shown that statistically optimized near field acoustic holography based on measurement with an array of pressure-velocity transducers makes it possible to distinguish between sources on the two sides of the array and thus suppress the influence of a disturbing source [F...

  17. Near field acoustic holography based on the equivalent source method and pressure-velocity transducers

    DEFF Research Database (Denmark)

    Zhang, Y.-B.; Chen, X.-Z.; Jacobsen, Finn

    2009-01-01

    The advantage of using the normal component of the particle velocity rather than the sound pressure in the hologram plane as the input of conventional spatial Fourier transform based near field acoustic holography (NAH) and also as the input of the statistically optimized variant of NAH has...

  18. Measurements of Surface Ocean Carbon Dioxide Partial Pressure During WOCE; FINAL

    International Nuclear Information System (INIS)

    Weiss, R.F.

    1998-01-01

    All of the technical goals of the World Ocean Circulation Experiment (WOCE) field program which were supported under the Department of Energy research grant ''Measurements of Surface Ocean Carbon Dioxide Partial Pressure During WOCE'' (DE-FG03-90ER60981) have been met. This has included the measurement of the partial pressures of carbon dioxide (C0(sub 2)) and nitrous oxide (N(sub 2)O) in both the surface ocean and the atmosphere on 24 separate shipboard expedition legs of the WOCE Hydrographic Programme. These measurements were made in the Pacific, Indian and Atlantic Oceans over a six-and-a-half year period, and over a distance of nearly 200,000 kilometers of ship track. The total number of measurements, including ocean measurements, air measurements and standard gas measurements, is about 136,000 for each gas, or about 34,000 measurements of each gas in the ocean and in the air. This global survey effort is directed at obtaining a better understanding of the role of the oceans in th e global atmospheric budgets of two important natural and anthropogenic modulators of climate through the ''greenhouse effect'', CO(sub 2) and N(sub 2)O, and an important natural and anthropogenic modulator of the Earth's protective ozone layer through catalytic processes in the stratosphere, N(sub 2)O. For both of these compounds, the oceans play a major role in their global budgets. In the case of CO(sub 2), roughly half of the anthropogenic production through the combustion of fossil fuels has been absorbed by the world's oceans. In the case of N(sub 2)O, roughly a third of the natural flux to the atmosphere originates in the oceans. As the interpretation of the variability in the oceanic distributions of these compounds improves, measurements such as those supported by this research project are playing an increasingly important role in improving our understanding of natural and anthropogenic influences on climate and ozone

  19. The effect of surface pressure modification on the speed of vortex rings

    Energy Technology Data Exchange (ETDEWEB)

    Partridge, Matthew; Davis, Frank; Higson, Seamus P J [Centre of Biomedical Imaging, Cranfield University, Cranfield MK43 0AL (United Kingdom); James, Stephen W; Tatam, Ralph P, E-mail: f.davis@cranfield.ac.uk [Engineering Photonics, School of Engineering, Cranfield University, Cranfield MK43 0AL (United Kingdom)

    2014-10-01

    A series of experiments investigating the relationship between surface pressure, monolayer elasticity and the speed of vortex rings is presented. A drop of water, when touched to the surface of a larger body of water, will coalesce and form a vortex ring that moves perpendicularly to the surface of the water. The speed of the vortex ring movement away from the surface of the water has been seen to be sensitive to the presence of monolayer materials. Here we explore the influence of four monolayer forming materials, stearic acid, tricosanoic acid, 4-tert butyl calix[4]arene and calix[4]resorcarene (C11), on the properties of vortex rings. For each material, the speed of the vortex rings through the water was measured at a range of surface pressures. The speed was found to increase in a linear fashion until surface pressures greater than 30 mN m{sup −1}, where the ring’s speed decreased towards the value measured in the absence of a monolayer. Analysis of the results suggests a future route toward a better understanding of the mechanisms involved.

  20. Durability of simulated waste glass: effects of pressure and formation of surface layers

    International Nuclear Information System (INIS)

    Wicks, G.G.; Mosley, W.C.; Whitkop, P.G.; Saturday, K.A.

    1981-01-01

    The leaching behavior of simulated Savannah River Plant (SRP) waste glass was studied at elevated pressures and anticipated storage temperatures. An integrated approach, which combined leachate solution analyses with both bulk and surface studies, was used to study the corrosion process. Compositions of leachates were evaluated by colorimetry and atomic absorption. Used in the bulk and surface analyses were optical microscopy, scanning electron microscopy, x-ray energy spectroscopy, wide-angle x-ray, diffraction, electron microprobe analysis, infrared reflectance spectroscopy, electron spectroscopy for chemical analysis, and Auger electron spectroscopy. Results from this study show that there is no significant adverse effect of pressure, up to 1500 psi and 90 0 C, on the chemical durability of simulated SPR waste glass leached for one month in deionized water. In addition, the leached glass surface layer was characterized by an adsorbed film rich in minor constituents from the glass. This film remained on the glass surface even after leaching in relatively alkaline solutions at elevated pressures at 90 0 C for one month. The sample surface area to volume of leachant ratios (SA/V) was 10:1 cm -1 and 1:10 cm -1 . The corrosion mechanisms and surface and subsurface layers produced will be discussed along with the potential importance of these results to repository storage

  1. Effects of surface and bulk transverse fields on critical behaviour of ferromagnetic films

    International Nuclear Information System (INIS)

    Saber, A.; Lo Russo, S.; Mattei, G.

    2002-02-01

    The influence of surface and bulk transverse fields on the critical behaviour of a ferromagnetic Ising film is studied using the effective field theory based on a single-site cluster method. Surface exchange enhancement is considered and a critical value is obtained. The dependence of the critical uniform transverse field on film thickness, phase diagrams in the fields, critical surface transverse field versus the bulk one, and exchange coupling ratio are presented. (author)

  2. Ferromagnetic transitions of a spin-one Ising film in a surface and bulk transverse fields

    International Nuclear Information System (INIS)

    Saber, A.; Lo Russo, S.; Mattei, G.; Mattoni, A.

    2002-01-01

    Using the effective field theory method, we have calculated the Curie temperature of a spin-one Ising ferromagnetic film in a surface and bulk transverse fields. Numerical calculations give phase diagrams under various parameters. Surface exchange enhancement is considered. The dependence of the critical transverse field on film thickness, and phase diagrams in the fields, critical surface transverse field versus the bulk one are presented

  3. Surface pressure model for simple delta wings at high angles of attack

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    characteristics. Flight mechanics analysis is primarily concerned with the aerodynamic data composed ... static data are the limiting case of unsteady flow pattern as time tends to infinity (or at least a few times the .... as the qualitative changes in the surface pressure model are independently confirmed by Roos. & Kegelman ...

  4. Analysis of the pressure fields in a swirling annular jet flow

    Science.gov (United States)

    Percin, M.; Vanierschot, M.; Oudheusden, B. W. van

    2017-12-01

    In this paper, we investigate the flow structures and pressure fields of a free annular swirling jet flow undergoing vortex breakdown. The flow field is analyzed by means of time-resolved tomographic particle image velocimetry measurements, which enable the reconstruction of the three-dimensional time-resolved pressure fields using the governing flow equations. Both time-averaged and instantaneous flow structures are discussed, including a characterization of the first- and second-order statistical moments. A Reynolds decomposition of the flow field shows that the time-averaged flow is axisymmetric with regions of high anisotropic Reynolds stresses. Two recirculation zones exist that are surrounded by regions of very intense mixing. Notwithstanding the axisymmetric nature of the time-averaged flow, a non-axisymmetric structure of the instantaneous flow is revealed, comprising a central vortex core which breaks up into a precessing vortex core. The winding sense of this helical structure is opposite to the swirl direction and it is wrapped around the vortex breakdown bubble. It precesses around the central axis of the flow at a frequency corresponding to a Strouhal number of 0.27. The precessing vortex core is associated with a low-pressure region along the central axis of the jet and the maximum pressure fluctuations occur upstream of the vortex breakdown location, where the azimuthal velocity component also reaches peak values as a result of the inward motion of the fluid and the conservation of angular momentum. The POD analysis of the pressure fields suggests that the precessing helical vortex formation is the dominant coherent structure in the instantaneous flow.

  5. Molecular Dynamics Simulation of Water Nanodroplets on Silica Surfaces at High Air Pressures

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Jaffe, Richard Lawrence; Walther, Jens Honore

    2010-01-01

    e.g., nanobubbles. In the present work we study the role of air on the wetting of hydrophilic systems. We conduct molecular dynamics simulations of a water nanodroplet on an amorphous silica surface at different air pressures. The interaction potentials describing the silica, water, and air...... are obtained from the literature. The silica surface is modeled by a large 32 ⨯ 32 ⨯ 2 nm amorphous SiO2 structure consisting of 180000 atoms. The water consists of 18000 water molecules surrounded by N2 and O2 air molecules corresponding to air pressures of 0 bar (vacuum), 50 bar, 100 bar and 200 bar. We...... the effect of air and find a consistent increase in the water contact angle reaching 53º at 200 bar air pressure. These results are important for the creation and stability of nanobubbles at hydrophilic interfaces....

  6. Near-field acoustic holography with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    of the particle velocity has notable potential in NAH, and furthermore, combined measurement of sound pressure and particle velocity opens a new range of possibilities that are examined in this study. On this basis, sound field separation methods have been studied, and a new measurement principle based on double...... layer measurements of the particle velocity has been proposed. Also, the relation between near-field and far-field radiation from sound sources has been examined using the concept of the supersonic intensity. The calculation of this quantity has been extended to other holographic methods, and studied...

  7. Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity.

    Science.gov (United States)

    Wong, Tak-Sing; Kang, Sung Hoon; Tang, Sindy K Y; Smythe, Elizabeth J; Hatton, Benjamin D; Grinthal, Alison; Aizenberg, Joanna

    2011-09-21

    Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging. Inspirations from natural nonwetting structures, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air-liquid interface. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis, failure under pressure and upon physical damage, inability to self-heal and high production cost. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach-inspired by Nepenthes pitcher plants-is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert 'slippery' interface. This surface outperforms its natural counterparts and state-of-the-art synthetic liquid-repellent surfaces in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1-1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and

  8. Pressurization Risk Assessment of CO2 Reservoirs Utilizing Design of Experiments and Response Surface Methods

    Science.gov (United States)

    Guyant, E.; Han, W. S.; Kim, K. Y.; Park, E.; Han, K.

    2015-12-01

    Monitoring of pressure buildup can provide explicit information on reservoir integrity and is an appealing tool, however pressure variation is dependent on a variety of factors causing high uncertainty in pressure predictions. This work evaluated pressurization of a reservoir system in the presence of leakage pathways as well as exploring the effects of compartmentalization of the reservoir utilizing design of experiments (Definitive Screening, Box Behnken, Central Composite, and Latin Hypercube designs) and response surface methods. Two models were developed, 1) an idealized injection scenario in order to evaluate the performance of multiple designs, and 2) a complex injection scenario implementing the best performing design to investigate pressurization of the reservoir system. A holistic evaluation of scenario 1, determined that the Central Composite design would be used for the complex injection scenario. The complex scenario evaluated 5 risk factors: reservoir, seal, leakage pathway and fault permeabilities, and horizontal position of the pathway. A total of 60 response surface models (RSM) were developed for the complex scenario with an average R2 of 0.95 and a NRMSE of 0.067. Sensitivity to the input factors was dynamic through space and time; at the earliest time (0.05 years) the reservoir permeability was dominant, and for later times (>0.5 years) the fault permeability became dominant for all locations. The RSM's were then used to conduct a Monte Carlo Analysis to further analyze pressurization risks, identifying the P10, P50, P90 values. This identified the in zone (lower) P90 values as 2.16, 1.77, and 1.53 MPa and above zone values of 1.35, 1.23, 1.09 MPa for monitoring locations 1, 2, and 3, respectively. In summary, the design of experiments and response surface methods allowed for an efficient sensitivity and uncertainty analysis to be conducted permitting a complete evaluation of the pressurization across the entire parameter space.

  9. Surface kinetics for catalytic combustion of hydrogen-air mixtures on platinum at atmospheric pressure in stagnation flows

    Science.gov (United States)

    Ikeda, H.; Sato, J.; Williams, F. A.

    1995-03-01

    Experimental studies of the combustion of premixed hydrogen-air mixtures impinging on the surface of a heated platinum plate at normal atmospheric pressure were performed and employed to draw inferences concerning surface reaction mechanisms and rate parameters applicable under practical conditions of catalytic combustion. Plate and gas temperatures were measured by thermocouples, and concentration profiles of major stable species in the gas were measured by gas-chromatographic analyses of samples withdrawn by quartz probes. In addition, ignition and extinction phenomena were recorded and interpreted with the aid of a heat balance at the surface and a previous flow-field analysis of the stagnation-point boundary layer. From the experimental and theoretical results, conclusions were drawn concerning the surface chemical-kinetic mechanisms and values of the elementary rate parameters that are consistent with the observations. In particular, the activation energy for the surface oxidation step H + OH → H 2O is found to be appreciably less at these high surface coverages than in the low-coverage limit.

  10. Supersonic flow over a pitching delta wing using surface pressure measurements and numerical simulations

    Directory of Open Access Journals (Sweden)

    Mostafa HADIDOOLABI

    2018-01-01

    Full Text Available Experimental and numerical methods were applied to investigating high subsonic and supersonic flows over a 60° swept delta wing in fixed state and pitching oscillation. Static pressure coefficient distributions over the wing leeward surface and the hysteresis loops of pressure coefficient versus angle of attack at the sensor locations were obtained by wind tunnel tests. Similar results were obtained by numerical simulations which agreed well with the experiments. Flow structure around the wing was also demonstrated by the numerical simulation. Effects of Mach number and angle of attack on pressure distribution curves in static tests were investigated. Effects of various oscillation parameters including Mach number, mean angle of attack, pitching amplitude and frequency on hysteresis loops were investigated in dynamic tests and the associated physical mechanisms were discussed. Vortex breakdown phenomenon over the wing was identified at high angles of attack using the pressure coefficient curves and hysteresis loops, and its effects on the flow features were discussed.

  11. Comparative study on two different seal surface structure for reactor pressure vessel sealing behavior

    International Nuclear Information System (INIS)

    Chen Jun; Xiong Guangming; Deng Xiaoyun

    2014-01-01

    The seal surface structure is very important to reactor pressure vessel (RPV) sealing behavior. In this paper, two 3-D RPV sealing analysis finite models have been established with different seal surface structures, in order to study the influence of two structures. The separation of RPV upper and lower flanges, bolt loads and etc. are obtained, which are used to evaluate the sealing behavior of the RPV. Meanwhile, the comparative analysis of safety margin of two seal surface structural had been done, which provides the theoretical basis for RPV seal structure design optimization. (authors)

  12. Surface modification of nanofibrillated cellulose films by atmospheric pressure dielectric barrier discharge

    DEFF Research Database (Denmark)

    Siró, Istvan; Kusano, Yukihiro; Norrman, Kion

    2013-01-01

    of atmospheric pressure plasma treatment, the water contact angle of NFC films increased and the values were comparable with those of PLA films. On the other hand, surface chemical characterization revealed inhomogeneity of the plasma treatment and limited improvement in adhesion between NFC and PLA films......A dielectric barrier discharge in a gas mixture of tetrafluoromethane (CF4) and O2 was used for tailoring the surface properties of nanofibrillated cellulose (NFC) films. The surface chemical composition of plasma-modified NFC was characterized by means of X-ray photoelectron spectroscopy and time....... Further research in this direction is required in order to enhance the uniformity of the plasma treatment results....

  13. Atmospheric-Pressure Plasma Jet Surface Treatment for Use in Improving Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-06

    Atmospheric-pressure plasma jets (APPJs) are a method of plasma treatment that plays an important role in material processing and modifying surface properties of materials, especially polymers. Gas plasmas react with polymer surfaces in numerous ways such as oxidation, radical formation, degradation, and promotion of cross-linking. Because of this, gas and plasma conditions can be explored for chosen processes to maximize desired properties. The purpose of this study is to investigate plasma parameters in order to modify surface properties for improved adhesion between aluminum and epoxy substrates using two types of adhesives. The background, results to date, and future work will be discussed.

  14. Study on hot melt pressure sensitive coil material for removing surface nuclear pollution dust

    Science.gov (United States)

    Wang, Jing; Li, Jiao; Wang, Jianhui; Zheng, Li; Li, Jian; Lv, Linmei

    2018-02-01

    A new method for removing surface nuclear pollution by using hot melt pressure sensitive membrane was presented. The hot melt pressure sensitive membrane was designed and prepared by screening hot melt pressure sensitive adhesive and substrate. The simulated decontamination test of the hot melt pressure sensitive membrane was performed by using 100 mesh and 20 mesh standard sieve dust for simulation of nuclear explosion fall ash and radioactive contaminated particles, respectively. It was found that the single decontamination rate of simulated fall ash and contaminated particles were both above 80% under pressure conditions of 25kPa or more at 140°C. And the maximum single decontamination rate was 92.5%. The influence of heating temperature and pressure on the decontamination rate of the membrane was investigated at the same time. The results showed that higher heating temperature could increase the decontamination rate by increasing the viscosity of the adhesive. When the adhesive amount of the adhesive layer reached saturation, a higher pressure could increase the single decontamination rate also.

  15. High-pressure catalytic reactions over single-crystal metal surfaces

    Science.gov (United States)

    Rodriguez, JoséA.; Wayne Goodman, D.

    1991-11-01

    Studies dealing with high-pressure catalytic reactions over single-crystal surfaces are reviewed. The coupling of an apparatus for the measurement of reaction kinetics at elevated pressures with an ultrahigh vacuum system for surface analysis allows detailed study of structure sensitivity, the effects of promoters and inhibitors on catalytic activity, and, in certain cases, identification of reaction intermediates by post-reaction surface analysis. Examples are provided which demonstrate the relevance of single-crystal studies for modeling the behaviour of high-surface-area supported catalysts. Studies of CO methanation and CO oxidation over single-crystal surfaces provide convincing evidence that these reactions are structure insensitive. For structure-sensitive reactions (ammonia synthesis, alkane hydrogenolysis, alkane isomerization, water-gas shift reaction, etc.) model single-crystal studies allow correlations to be established between surface structure and catalytic activity. The effects of both electronegative (S and P) and electropositive (alkali metals) impurities upon the catalytic activity of metal single crystals for ammonia synthesis, CO methanation, alkane hydrogenolysis, ethylene epoxidation and water-gas shift are discussed. The roles of "ensemble" and "ligand" effects in bimetallic catalysts are examined in light of data obtained using surfaces prepared by vapor-depositing one metal onto a crystal face of a dissimilar metal.

  16. Adsorbate induced surface alloy formation investigated by near ambient pressure X-ray photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Nierhoff, Anders Ulrik Fregerslev; Conradsen, Christian Nagstrup; McCarthy, David Norman

    2014-01-01

    Formation of meta-stable surface-alloys can be used as a way to tune the binding strength of reaction intermediates and could therefore be used as improved catalyst materials for heterogeneous catalysis. Understanding the role of adsorbates on such alloy surfaces can provide new insights for engi...... and bulk Pt contributions. The study provides direct evidence on how it is possible to monitor the surface structure under near operation conditions. © 2014 Elsevier B.V. All rights reserved.......Formation of meta-stable surface-alloys can be used as a way to tune the binding strength of reaction intermediates and could therefore be used as improved catalyst materials for heterogeneous catalysis. Understanding the role of adsorbates on such alloy surfaces can provide new insights...... for engineering of more active or selective catalyst materials. Dynamical surface changes on alloy surfaces due to the adsorption of reactants in high gas pressures are challenging to investigate using standard characterization tools. Here we apply synchrotron illuminated near ambient pressure X-ray photoelectron...

  17. Surface modification of polyester synthetic leather with tetramethylsilane by atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Kan, C.W.; Kwong, C.H.; Ng, S.P.

    2015-01-01

    Highlights: • Atmospheric pressure plasma treatment improved surface performance of polyester synthetic leather with tetramethylsilane. • XPS and FTIR confirmed the deposition of organosilanes on the sample's surface. • Contact angle increases to 138° after plasma treatment. - Abstract: Much works have been done on synthetic materials but scarcely on synthetic leather owing to its surface structures in terms of porosity and roughness. This paper examines the use of atmospheric pressure plasma (APP) treatment for improving the surface performance of polyester synthetic leather by use of a precursor, tetramethylsilane (TMS). Plasma deposition is regarded as an effective, simple and single-step method with low pollution. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) confirm the deposition of organosilanes on the sample's surface. The results showed that under a particular combination of treatment parameters, a hydrophobic surface was achieved on the APP treated sample with sessile drop static contact angle of 138°. The hydrophobic surface is stable without hydrophilic recovery 30 days after plasma treatment

  18. Development of bio/blood compatible polypropylene through low pressure nitrogen plasma surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Gomathi, N., E-mail: gomathi@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Department of Space, Trivandrum, 695547 (India); Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, 721302 (India); Rajasekar, R. [Materials Science Center, Indian Institute of Technology, Kharagpur, 721302 (India); Department of BIN Fusion Technology, Chonbuk National University, Jeonju, Jeonbuk, 561-756 (Korea, Republic of); Babu, R. Rajesh [Rubber Technology Center, Indian Institute of Technology, Kharagpur, 721302 (India); Advanced Tyre Research, Apollo Tyres, Baroda, 391750 (India); Mishra, Debasish [Department of Biotechnolgy, Indian Institute of Technology, Kharagpur, 721302 (India); Neogi, S. [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, 721302 (India)

    2012-10-01

    Surface modification of polypropylene by nitrogen containing plasma was performed in this work in order to improve the wettability which resulted in enhanced biocompatibility and blood compatibility. Various nitrogen containing functional groups as well as oxygen containing functional groups were found to be incorporated to the polymer surface during plasma treatment and post plasma reaction respectively. Wettability of the polymers was evaluated by static contact angle measurement to show the improvement in hydrophilicity of plasma treated polypropylene. Cross linking and surface modification were reported to be dominating in the case of nitrogen plasma treatment compared to degradation. The effect of various process variables namely power, pressure, flow rate and treatment time on surface energy and weight loss was studied at various levels according to the central composite design of response surface methodology (RSM). Except pressure the other variables resulted in increased weight loss due to etching whereas with increasing pressure weight loss was found to increase and then decrease. The effect of process variables on surface morphology of polymers was evaluated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Well spread fibroblast cells on nitrogen plasma treated polypropylene due to the presence of CO, NH{sup 2+} and NH{sup +} was observed. Reduced platelet adhesion and increased partial thromboplastin time evidenced the increased blood compatibility. - Highlights: Black-Right-Pointing-Pointer Improved biocompatibility and blood compatibility of polypropylene. Black-Right-Pointing-Pointer Nitrogen plasma surface modification. Black-Right-Pointing-Pointer Maintaining a balance between polar group incorporation and weight loss due to etching. Black-Right-Pointing-Pointer Optimization of process conditions by response surface methodology.

  19. Development of bio/blood compatible polypropylene through low pressure nitrogen plasma surface modification

    International Nuclear Information System (INIS)

    Gomathi, N.; Rajasekar, R.; Babu, R. Rajesh; Mishra, Debasish; Neogi, S.

    2012-01-01

    Surface modification of polypropylene by nitrogen containing plasma was performed in this work in order to improve the wettability which resulted in enhanced biocompatibility and blood compatibility. Various nitrogen containing functional groups as well as oxygen containing functional groups were found to be incorporated to the polymer surface during plasma treatment and post plasma reaction respectively. Wettability of the polymers was evaluated by static contact angle measurement to show the improvement in hydrophilicity of plasma treated polypropylene. Cross linking and surface modification were reported to be dominating in the case of nitrogen plasma treatment compared to degradation. The effect of various process variables namely power, pressure, flow rate and treatment time on surface energy and weight loss was studied at various levels according to the central composite design of response surface methodology (RSM). Except pressure the other variables resulted in increased weight loss due to etching whereas with increasing pressure weight loss was found to increase and then decrease. The effect of process variables on surface morphology of polymers was evaluated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Well spread fibroblast cells on nitrogen plasma treated polypropylene due to the presence of CO, NH 2+ and NH + was observed. Reduced platelet adhesion and increased partial thromboplastin time evidenced the increased blood compatibility. - Highlights: ► Improved biocompatibility and blood compatibility of polypropylene. ► Nitrogen plasma surface modification. ► Maintaining a balance between polar group incorporation and weight loss due to etching. ► Optimization of process conditions by response surface methodology.

  20. Effect of high-hydrostatic pressure and moderate-intensity pulsed electric field on plum.

    Science.gov (United States)

    García-Parra, J; González-Cebrino, F; Delgado-Adámez, J; Cava, R; Martín-Belloso, O; Élez-Martínez, P; Ramírez, R

    2018-03-01

    Moderate intensity pulse electric fields were applied in plum with the aim to increase bioactive compounds content of the fruit, while high-hydrostatic pressure was applied to preserve the purées. High-hydrostatic pressure treatment was compared with an equivalent thermal treatment. The addition of ascorbic acid during purée manufacture was also evaluated. The main objective of this study was to assess the effects on microorganisms, polyphenoloxidase, color and bioactive compounds of high-hydrostatic pressure, or thermal-processed plum purées made of moderate intensity pulse electric field-treated or no-moderate intensity pulse electric field-treated plums, after processing during storage. The application of moderate intensity pulse electric field to plums slightly increased the levels of anthocyanins and the antioxidant activity of purées. The application of Hydrostatic-high pressure (HHP) increased the levels of bioactive compounds in purées, while the thermal treatment preserved better the color during storage. The addition of ascorbic acid during the manufacture of plum purée was an important factor for the final quality of purées. The color and the bioactive compounds content were better preserved in purées with ascorbic acid. The no inactivation of polyphenoloxidase enzyme with treatments applied in this study affected the stability purées. Probably more intense treatments conditions (high-hydrostatic pressure and thermal treatment) would be necessary to reach better quality and shelf life during storage.

  1. Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Jia Caixia; Chen Ping; Liu Wei; Li Bin; Wang Qian

    2011-01-01

    Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm 3 plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, C=O and O=C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

  2. Further fields of application for prestressed cast iron pressure vessels (PCIV)

    International Nuclear Information System (INIS)

    Guelicher, L.; Schilling, F.E.

    1977-01-01

    The redundancy of the prestressing system of prestressed structures as well as the clear separation of sealing and load-carrying functions of prestressed cast iron pressure vessels offer substantial advantages over conventional welded steel pressure vessels. Because of the temperature resistance of cast iron up to 400 0 C it is possible to build prestressed pressure vessels commercially as hot-working structures. The compressive strength of cast iron, which is 25 times as high as that of concrete allows for a very compact design of the PCIV. Further specific properties of the PCIV like pre-fabrication of the vessel in the production plant - made possible by a structure assembled from segments - short assembly periods at the construction site etc., may open more fields of application. - PCIV as pressurized storage tanks for the emergency shut down system in nuclear power stations. - PCIV as high pressure vessel for the chemical industry. - PCIV as energy storage. - PCIV for light water reactors. - PCIV as burst protection. It is concluded that the application of prestressed cast iron promises to be successful where either structures with large volumes and high pressures and/or temperatures are required or where aspects of safety allow for efficient use of prestressed structures. (Auth.)

  3. Mechanics Evolution Characteristics Analysis of Pressure-arch in Fully-mechanized Mining Field

    Directory of Open Access Journals (Sweden)

    S.R. Wang

    2014-09-01

    Full Text Available Based on a practical engineering, the three-dimension computational model was built using FLAC3D under the fullymechanized mining condition. Considering four variation factors, such as the distance of mining advancing, the strength of the surrounding rock, the speed of mining advancing and the dip angle of the coal seam, the mechanics evolution characteristics of the pressure-arch were analyzed. The result showed that for the horizontal seam, the geometric shape of the pressure-arch varied from flat arch to round arch gradually and the height and thickness of the pressure-arch also increased; the maximum principal stress in the skewback also increased with the working face advancing. With the strength of the surrounding rock from soft to hard, the arch thickness reduced, and the arch loading decreased. To improve the mining speed can do some contributions to the stability of the pressure-arch in the mining field. With the increase of dip angle of the seam, the pressure-arch displayed an asymmetric shape, the vault was tilted and moved to the upward direction. At the same time, the thickness of the pressure-arch increased, and the stress concentration in the skewback tended to be further intensified.

  4. Comparison of pressure reconstruction approaches based on measured and simulated velocity fields

    Directory of Open Access Journals (Sweden)

    Manthey Samuel

    2017-09-01

    Full Text Available The pressure drop over a pathological vessel section can be used as an important diagnostic indicator. However, it cannot be measured non-invasively. Multiple approaches for pressure reconstruction based on velocity information are available. Regarding in-vivo data introducing uncertainty these approaches may not be robust and therefore validation is required. Within this study, three independent methods to calculate pressure losses from velocity fields were implemented and compared: A three dimensional and a one dimensional method based on the Pressure Poisson Equation (PPE as well as an approach based on the work-energy equation for incompressible fluids (WERP. In order to evaluate the different approaches, phantoms from pure Computational Fluid Dynamics (CFD simulations and in-vivo PC-MRI measurements were used. The comparison of all three methods reveals a good agreement with respect to the CFD pressure solutions for simple geometries. However, for more complex geometries all approaches lose accuracy. Hence, this study demonstrates the need for a careful selection of an appropriate pressure reconstruction algorithm.

  5. Investigation of the surface free energy of the ITO thin films deposited under different working pressure

    International Nuclear Information System (INIS)

    Özen, Soner; Pat, Suat; Korkmaz, Şadan; Şenay, Volkan

    2016-01-01

    This study discusses the influence of working pressure on the surface energy of the ITO thin films produced by radio frequency magnetron sputtering method. Optical tensiometer (Attension Theta Lite) is used for evaluating wetting behavior of the water droplet on the film surface and Equation of State method was selected to determine surface free energy for this study. Equation of state method does not divide the surface tension into different components such as polar, dispersive, acid-base. It is calculated the surfaces’ free energy measuring the contact angle with a single liquid. The surface free energy value was in the range of 15-31 mN/m. Also, the transmittances were determined in the wavelength range between 200 and 1000 nm using the UNICO 4802 UV-Vis double beam spectrophotometer. Transmittances of the produced ITO thin films are greater than %70 in the visible range.

  6. Investigation of the surface free energy of the ITO thin films deposited under different working pressure

    Energy Technology Data Exchange (ETDEWEB)

    Özen, Soner, E-mail: osoner@ogu.edu.tr; Pat, Suat; Korkmaz, Şadan [Eskişehir Osmangazi University, Physics Department, 26480 (Turkey); Şenay, Volkan [Eskişehir Osmangazi University, Physics Department, 26480 (Turkey); Bayburt University, Primary Science Education Department, 69000 (Turkey)

    2016-03-25

    This study discusses the influence of working pressure on the surface energy of the ITO thin films produced by radio frequency magnetron sputtering method. Optical tensiometer (Attension Theta Lite) is used for evaluating wetting behavior of the water droplet on the film surface and Equation of State method was selected to determine surface free energy for this study. Equation of state method does not divide the surface tension into different components such as polar, dispersive, acid-base. It is calculated the surfaces’ free energy measuring the contact angle with a single liquid. The surface free energy value was in the range of 15-31 mN/m. Also, the transmittances were determined in the wavelength range between 200 and 1000 nm using the UNICO 4802 UV-Vis double beam spectrophotometer. Transmittances of the produced ITO thin films are greater than %70 in the visible range.

  7. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    International Nuclear Information System (INIS)

    Štěpánová, Vlasta; Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana; Černák, Mirko

    2015-01-01

    Graphical abstract: - Highlights: • Rabbit fibres plasma treatment is an effective method for fibres modification. • Atmospheric pressure plasma treatment is able to affect fibres properties. • Surface changes on fibres after plasma treatment were analysed via SEM, ATR-FTIR, XPS. • Significant increase of fibres wettability after plasma treatment was observed. • Plasma treatment at atmospheric pressure can replace the chemical treatment of fibres. - Abstract: We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.

  8. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    Energy Technology Data Exchange (ETDEWEB)

    Štěpánová, Vlasta, E-mail: vstepanova@mail.muni.cz [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Černák, Mirko [Department of Physical Electronics, Faculty of Science Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic); Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina F2, 842 48 Bratislava (Slovakia)

    2015-11-15

    Graphical abstract: - Highlights: • Rabbit fibres plasma treatment is an effective method for fibres modification. • Atmospheric pressure plasma treatment is able to affect fibres properties. • Surface changes on fibres after plasma treatment were analysed via SEM, ATR-FTIR, XPS. • Significant increase of fibres wettability after plasma treatment was observed. • Plasma treatment at atmospheric pressure can replace the chemical treatment of fibres. - Abstract: We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.

  9. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    Science.gov (United States)

    Lopaev, D. V.; Malykhin, E. M.; Zyryanov, S. M.

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature TV was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O(3P), O2, O2(1Δg) and O3 molecules in different vibrational states. The agreement of O3 and O(3P) density profiles and TV calculated in the model with observed ones was reached by varying the single model parameter—ozone production probability (\\gamma_{O_{3}}) on the quartz tube surface on the assumption that O3 production occurs mainly in the surface recombination of physisorbed O(3P) and O2. The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse \\gamma_{O_{3}} data obtained in the kinetic model. A good agreement between the experimental data and the data of both models—the kinetic 1D model and the phenomenological surface model—was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up the

  10. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    International Nuclear Information System (INIS)

    Lopaev, D V; Malykhin, E M; Zyryanov, S M

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O 3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature T V was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O 3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O( 3 P), O 2 , O 2 ( 1 Δ g ) and O 3 molecules in different vibrational states. The agreement of O 3 and O( 3 P) density profiles and T V calculated in the model with observed ones was reached by varying the single model parameter-ozone production probability (γ O 3 ) on the quartz tube surface on the assumption that O 3 production occurs mainly in the surface recombination of physisorbed O( 3 P) and O 2 . The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse γ O 3 data obtained in the kinetic model. A good agreement between the experimental data and the data of both models-the kinetic 1D model and the phenomenological surface model-was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O 3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up

  11. Surface modification of polytetrafluoroethylene film using the atmospheric pressure glow discharge in air

    International Nuclear Information System (INIS)

    Fang, Z; Qiu, Y; Luo, Y

    2003-01-01

    The atmospheric pressure glow discharge (APGD) is more promising in industrial applications compared with glow discharges in a gas other than air or in low-pressure air, which needs an expensive vacuum system. In this paper, the APGD and dielectric barrier discharge (DBD) are generated in atmospheric air using a power-frequency voltage source, and the transition from DBD to APGD is achieved by varying the electrode arrangement. The differences between their discharge characteristics are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena. The effects of APGD and DBD on polytetrafluoroethylene (PTFE) surface modification are studied. The surface properties are characterized by contact angle measurement, x-ray photoelectron spectroscopy and scanning electron microscopy. It is found that the APGD and DBD treatments modify the PTFE surface in both morphology and composition. APGD is more effective in PTFE surface modification than DBD as it can modify the surface more uniformly, implant more oxygen atoms into the surface and make the contact angle decline to a lower level. The experimental results are discussed

  12. Surface treatment of polyethylene terephthalate film using atmospheric pressure glow discharge in air

    International Nuclear Information System (INIS)

    Fang Zhi; Qiu Yuchang; Wang Hui

    2004-01-01

    Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the surface oxygen content of PET surface increases to 39%, and the water contact angle decreases to 19 degree, respectively. (authors)

  13. The Role of Atmospheric Pressure on Surface Thermal Inertia for Early Mars Climate Modeling

    Science.gov (United States)

    Mischna, M.; Piqueux, S.

    2017-12-01

    On rocky bodies such as Mars, diurnal surface temperatures are controlled by the surface thermal inertia, which is a measure of the ability of the surface to store heat during the day and re-radiate it at night. Thermal inertia is a compound function of the near-surface regolith thermal conductivity, density and specific heat, with the regolith thermal conductivity being strongly controlled by the atmospheric pressure. For Mars, current best maps of global thermal inertia are derived from the Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) spacecraft using bolometric brightness temperatures of the surface. Thermal inertia is widely used in the atmospheric modeling community to determine surface temperatures and to establish lower boundary conditions for the atmosphere. Infrared radiation emitted from the surface is key in regulating lower atmospheric temperatures and driving overall global circulation. An accurate map of surface thermal inertia is thus required to produce reasonable results of the present-day atmosphere using numerical Mars climate models. Not surprisingly, thermal inertia is also a necessary input into climate models of early Mars, which assume a thicker atmosphere, by as much as one to two orders of magnitude above the present-day 6 mb mean value. Early Mars climate models broadly, but incorrectly, assume the present day thermal inertia surface distribution. Here, we demonstrate that, on early Mars, when pressures were larger than today's, the surface layer thermal inertia was globally higher because of the increased thermal conductivity driven by the higher gas pressure in interstitial pore spaces within the soil. Larger thermal inertia reduces the diurnal range of surface temperature and will affect the size and timing of the modeled seasonal polar ice caps. Additionally, it will globally alter the frequency of when surface temperatures are modeled to exceed the liquid water melting point, and so results may

  14. Synchronous Surface Pressure and Velocity Measurements of standard model in hypersonic flow

    Directory of Open Access Journals (Sweden)

    Zhijun Sun

    2018-01-01

    Full Text Available Experiments in the Hypersonic Wind tunnel of NUAA(NHW present synchronous measurements of bow shockwave and surface pressure of a standard blunt rotary model (AGARD HB-2, which was carried out in order to measure the Mach-5-flow above a blunt body by PIV (Particle Image Velocimetry as well as unsteady pressure around the rotary body. Titanium dioxide (Al2O3 Nano particles were seeded into the flow by a tailor-made container. With meticulous care designed optical path, the laser was guided into the vacuum experimental section. The transient pressure was obtained around model by using fast-responding pressure-sensitive paint (PSPsprayed on the model. All the experimental facilities were controlled by Series Pulse Generator to ensure that the data was time related. The PIV measurements of velocities in front of the detached bow shock agreed very well with the calculated value, with less than 3% difference compared to Pitot-pressure recordings. The velocity gradient contour described in accord with the detached bow shock that showed on schlieren. The PSP results presented good agreement with the reference data from previous studies. Our work involving studies of synchronous shock-wave and pressure measurements proved to be encouraging.

  15. Development of Maximum Bubble Pressure Method for Surface Tension Measurement of High Viscosity Molten Silicate

    Science.gov (United States)

    Takeda, Osamu; Iwamoto, Hirone; Sakashita, Ryota; Iseki, Chiaki; Zhu, Hongmin

    2017-07-01

    A surface tension measurement method based on the maximum bubble pressure (MBP) method was developed in order to precisely determine the surface tension of molten silicates in this study. Specifically, the influence of viscosity on surface tension measurements was quantified, and the criteria for accurate measurement were investigated. It was found that the MBP apparently increased with an increase in viscosity. This was because extra pressure was required for the flowing liquid inside the capillary due to viscous resistance. It was also expected that the extra pressure would decrease by decreasing the fluid velocity. For silicone oil with a viscosity of 1000 \\hbox {mPa}{\\cdot }\\hbox {s}, the error on the MBP could be decreased to +1.7 % by increasing the bubble detachment time to 300 \\hbox {s}. However, the error was still over 1 % even when the bubble detachment time was increased to 600 \\hbox {s}. Therefore, a true value of the MBP was determined by using a curve-fitting technique with a simple relaxation function, and that was succeeded for silicone oil at 1000 \\hbox {mPa}{\\cdot } \\hbox {s} of viscosity. Furthermore, for silicone oil with a viscosity as high as 10 000 \\hbox {mPa}{\\cdot }\\hbox {s}, the apparent MBP approached a true value by interrupting the gas introduction during the pressure rising period and by re-introducing the gas at a slow flow rate. Based on the fundamental investigation at room temperature, the surface tension of the \\hbox {SiO}2-40 \\hbox {mol}%\\hbox {Na}2\\hbox {O} and \\hbox {SiO}2-50 \\hbox {mol}%\\hbox {Na}2\\hbox {O} melts was determined at a high temperature. The obtained value was slightly lower than the literature values, which might be due to the influence of viscosity on surface tension measurements being removed in this study.

  16. Use of Pressure-Redistributing Support Surfaces among Elderly Hip Fracture Patients across the Continuum of Care: Adherence to Pressure Ulcer Prevention Guidelines

    Science.gov (United States)

    Baumgarten, Mona; Margolis, David; Orwig, Denise; Hawkes, William; Rich, Shayna; Langenberg, Patricia; Shardell, Michelle; Palmer, Mary H.; McArdle, Patrick; Sterling, Robert; Jones, Patricia S.; Magaziner, Jay

    2010-01-01

    Purpose: To estimate the frequency of use of pressure-redistributing support surfaces (PRSS) among hip fracture patients and to determine whether higher pressure ulcer risk is associated with greater PRSS use. Design and Methods: Patients (n = 658) aged [greater than or equal] 65 years who had surgery for hip fracture were examined by research…

  17. Cardiovascular fluid dynamics. Methods for flow and pressure field analysis from magnetic resonance imaging

    International Nuclear Information System (INIS)

    Ebbers, T.

    2001-01-01

    Cardiovascular blood flow is highly complex and incompletely understood. Blood flow patterns are expected to influence the opening and closing of normal and prosthetic heart valves, the efficiency of cardiac filling and ejection, and the resistance to thrombus formation within the heart. Conventional diagnostic techniques are poorly suited to the study of the three-dimensional (3D) blood flow patterns in the heart chambers and large vessels. Noninvasive methods have also been inadequate in studying intracardiac pressure differences, which are the driving force of flow and are critical in the evaluation of many cardiovascular abnormalities. This thesis focuses on the development of non-invasive methods for analysis of 3D cardiovascular blood flow. Simultaneous study of cardiovascular fluid dynamics allowed knowledge exchange across the two disciplines, facilitating the development process and broadening the applicability of the methods. A time-resolved 3D phase-contrast Magnetic Resonance Imaging (MRI) technique was used to acquire the velocity vector field in a 3D volume encompassing the entire heart or a large vessel. Cardiovascular blood flow patterns were visualized by use of particle traces, which revealed, for instance, vortical flow patterns in the left atrium. By applying the Navier-Stokes equation along a user-defined line in the 3D velocity vector field, the relative pressure could be obtained as an excellent supplement to the flow pattern visualization. Using a delineation of the blood pool, the time-varying 3D relative pressure field in the human left ventricle was obtained from the velocity field by use of the pressure Poisson equation. A delineation of the heart muscle, a task that is almost impossible to perform on 3D MRI either automatically or manually, was also achieved by usage of particle traces. This segmentation allows automatic calculation of the 3D relative pressure field, as well as calculation of well-established parameters such as

  18. Effect of a pulsed magnetic field on terbium high pressure phase

    International Nuclear Information System (INIS)

    Tonkov, E.Yu.; Aptekar', I.L.; Degtyareva, V.F.; Ponomarev, B.K.; Tissen, V.G.

    1977-01-01

    Through the effect of an elevated (up to 90 kbar) quasi hydrostatic pressure the Tb 3 phase has been obtained having a samarium-resembling structure which remains metastable after the pressure has been removed. It is shown that the action of a pulse magnetic field reconvert the Tb 3 phase to the initial Tb 3 phase. The Tb 3 → Tb 2 transition begins at temperatures below 190 K, the quantity of the converted phase increasing as the temperature goes down. The Neel point has been observed in Tb 3 at about 190 K. The Tb 3 → Tb 2 transition can alternatively be effected by heating to about 200 deg C and under plastic strain. Magnetostriction of the antiferromagnetic Tb 3 phase can be the possible mechanism of the Tb 3 → Tb 2 transition under the effect of magnetic field

  19. Effect of high hydrostatic pressure, ultrasound and pulsed electric fields on milk composition and characteristics

    Directory of Open Access Journals (Sweden)

    Irena Jeličić

    2012-03-01

    Full Text Available High hydrostatic pressure, ultrasonication and pulsed eletrcic fields (PEF belong to novel food processing methods which are mostly implemented in combination with moderate temperatures and/ or in combination with each other in order to provide adequate microbiological quality with minimal losses of nutritional value. All of three mentioned methods have been intensively investigated for the purpose of inactivation and reduction of foodborne microorganisms present in milk and dairy products. However, a large number of scientific researches have been dedicated to investigation of impact of these methods on changes in constituents like milk fat, milk proteins and lactose as well as changes in mechanisms like renneting properties and coagulation of milk. The aim of this research was to give an overview of changes in milk constituents induced by high hydrostatic pressure, ultrasonification and pulsed electric field treatments as well as to suggest how these changes could improve conventional processes in the dairy industry.

  20. Field evaluation of skid resistant surfaces : final report : part I.

    Science.gov (United States)

    1970-06-01

    This project was undertaken to establish a thin bituminous surface course that would possess good skid resistant qualities as well as, being both economical and durable. : This is the final report on the evaluation of skid resistant surfaces which wa...

  1. Pressure-induced superconductivity in a ferromagnet, UGe sub 2 : resistivity measurements in a magnetic field

    CERN Document Server

    Kobayashi, T C; Tateiwa, N; Amaya, K; Haga, Y; Settai, R; Onuki, Y

    2002-01-01

    Electrical resistivity measurements in a magnetic field are carried out on UGe sub 2 which exhibits pressure-induced superconductivity. The superconductivity is observed from 1.06 to 1.44 GPa. In the temperature and field dependences of the resistivity at P > P sub C where the ferromagnetic ordering disappears, it is observed that the application of an external field along the a-axis increases the coefficient A of the Fermi-liquid behaviour (propor to AT sup 2) abruptly - corresponding to the metamagnetic transition. The characteristic enhancement of H sub C sub 2 is reconfirmed for H || a-axis. The upper critical field of H sub C sub 2 is anisotropic: H sub C sub 2 (T) exhibits positive curvature for H || b-axis and H || c-axis.

  2. High-pressure Moessbauer spectroscopy of perovskite high valence iron oxides under external magnetic field

    International Nuclear Information System (INIS)

    Kawakami, Takateru; Nasu, Saburo

    2005-01-01

    The magnetic properties of SrFeO 3 (SFO), CaFeO 3 (CFO) and Sr 2/3 La 1/3 FeO 3 (SLFO), which are perovskite iron oxides with a high valence state of Fe, have been investigated by high-pressure Moessbauer spectroscopy under external magnetic field. These perovskite oxides have been found to switch electronic ground state drastically from the antiferromagnetic (AF) state to the ferromagnetic (FM) state under high pressure. CFO and SLFO, which show a charge-disproportionation (CD: 2Fe 4+ → Fe 3+ + Fe 5+ and 3Fe 11/3+ → 2Fe 3+ + Fe 5+ , respectively) at low temperature, switch magnetic ordering from the AF state to the FM state simultaneously with the suppression of the CD in a critical pressure of about 19 and 23 GPa, respectively. SFO, which does not show any CD, switches its magnetic ordering from the AF state to the FM state at about 7 GPa. These pressure-induced transitions from the AF state to the FM state are accompanied by the discontinuous reduction of the magnetic hyperfine fields

  3. On the field dependent surface resistance of niobium on copper cavities

    CERN Document Server

    Junginger, Tobias

    2015-01-01

    The surface resistance Rs of superconducting cavities prepared by sputter coating a thin niobium film on a copper substrate increases significantly stronger with the applied RF field compared to cavities of bulk material. A possible cause is that due to the thermal boundary resistance between the copper substrate and the niobium film Rs is enhanced due to global heating of the inner cavity wall. Introducing helium gas in the cavity and measuring its pressure as a function of applied field allowed to conclude that the inner surface of the cavity is heated up by only 60+/-60 mK when Rs increases with Eacc by 100 nOhm. This is more than one order of magnitude less than what one would expect from global heating. Additionally the effect of cooldown speed and low temperature baking have been investigated in the framework of these experiments. It is shown that for current state of the art niobium on copper cavities there is only a detrimental effect of low temperature baking. A fast cooldown results in a lowered Rs.

  4. Effect of high hydrostatic pressure, ultrasound and pulsed electric fields on milk composition and characteristics

    OpenAIRE

    Irena Jeličić; Katarina Lisak; Rajka Božanić

    2012-01-01

    High hydrostatic pressure, ultrasonication and pulsed eletrcic fields (PEF) belong to novel food processing methods which are mostly implemented in combination with moderate temperatures and/ or in combination with each other in order to provide adequate microbiological quality with minimal losses of nutritional value. All of three mentioned methods have been intensively investigated for the purpose of inactivation and reduction of foodborne microorganisms present in milk and dairy products. ...

  5. Pressure and temperature fields and water released by concrete submitted to high heat fluxes

    International Nuclear Information System (INIS)

    Andrade Lima, F.R. de

    1982-01-01

    Inovations are introduced in the original program USINT considering thermal conductivity variations with the temperature. A subroutine - PLOTTI - is incorporate to the program aiming to obtain a graphic for results. The new program - USINTG - is used for calculating the field of pressure and temperature and the water released from the concrete structure during a simulation of sodium leak. The theoretical results obtained with USINTG are in good agreement with the experimental results previously obtained. (E.G.) [pt

  6. Watching the wind: seismic data contamination at long-periods due to atmospheric pressure-field-induced tilting

    Science.gov (United States)

    de Angelis, S.; Bodin, P.; Hagel, K.; Fletcher, D.

    2010-12-01

    Long-period noise generated by the elastic response of the Earth to atmospheric pressure fluctuations has long been recognized as a limiting factor for seismic investigations. The quality of seismic data recorded by sensitive, near-surface broadband seismometers can be severely corrupted by this effect. During the recent installation of a new broadband site on the Olympic Peninsula in Washington, the Pacific Northwest Seismic Network recorded and investigated elevated daytime noise levels at periods exceeding 30 seconds. Substantial power spectral density variations of the background noise field, 15-20 dB, were observed in the horizontal component seismograms. The pattern of the long-period noise exhibited striking correlations with local fluctuations of the air temperature and wind speed as measured nearby the seismic station by the National Weather Service Forecast Office, Seattle, Washington, and the National Oceanic and Atmospheric Administration. Several past studies have demonstrated that local wind systems may lead to variations of the atmospheric pressure field that deform the ground and perturb seismograms. The rotational component of this motion is detected by horizontal-component seismometers because at periods longer than the sensor’s low corner frequency the sensor is acting essentially as a tiltmeter. We obtained a transfer function that describes the response of the broadband seismometer to a tilt step change and estimated the amplitude of tilt noise to be on the order of 10-9 - 10-8 radians. Within the seismic pass-band of the sensor, it is not possible to remove the tilt signal from the observed seismograms because the details of the tilting depend on the pressure field variations, the compliance of the near surface to pressure variations, and the design and construction of the seismometer vault itself. At longer periods, using the seismic data to recover tilts of tectonic origin is made challenging because of the needed instrument correction

  7. The Effect of Fabric Position to the Distribution of Acoustic Pressure Field in Ultrasonic Bath

    Science.gov (United States)

    Gürses, B. O.; Özdemir, A. O.; Tonay, Ö.; Şener, M.; Perinçek, S.

    2017-10-01

    Nowadays, the use of ultrasonic energy in textile wet processes at industrial-scale is limited. It is largely due to the lack of understanding about design, operational and performance characteristics of the ultrasonic bath, suitable for textile treatments. In the context of this study, the effect of fabric position, as one of the design parameter, to the distribution of acoustic pressure field in ultrasonic bath was investigated. The ultrasonic bath in the size 20×30 cm2 with one transducer at frequency 40 kHz was used in experiments. The cotton fabric with 1 mm thickness was moved along vertical and horizontal directions of the ultrasonic bath. The acoustic field and cavitation volume density in the bath is analyzed by COMSOL Multiphysic. The cavitation volume density is calculated by comparing the pressure points in the bath with cavitation threshold pressure. Consequently, it was found that the position of the textile material in the ultrasonic bath is one of the most important factors to achieve the uniform and maximum acoustic cavitation field. So, it should be taken into consideration during the design of industrial-scale ultrasonic bath used in textile wet processes.

  8. Magnetic field and pressure dependant resistivity behaviour of MnAs

    Science.gov (United States)

    Satya, A. T.; Amaladass, E. P.; Mani, Awadhesh

    2018-04-01

    The studies on the effect of magnetic field and external pressure on temperature dependant electrical resistivity behaviour of polycrystalline MnAs have been reported. At ambient pressure, ρ(T) shows a first order magnetic transition associated with change in sign of the temperature coefficient of resistivity from positive in the ferromagnetic (FM) phase to negative in the paramagnetic (PM) phase. The magneto resistance is negative and shows a peak at the FM transition temperature (T C ). The first order hysteresis width decreases with increase in magnetic field and the intersection of extrapolated linear variations of T C with field for the cooling and warming cycles enabled determination of the tricritical point. At high pressures, ρ(T) displays non monotonic variation exhibiting a low temperature minimum ({T}\\min L) and a high temperature maximum ({T}\\max H) accompanying broad thermal hysteresis above {T}\\min L. It is surmised that spin disorder scattering is responsible for the resistivity behaviour above {T}\\min L and the essential features of ρ(T) are qualitatively explained using Kasuya theoretical model. Below the {T}\\min L, ρ(T) follows linear logarithmic temperature dependence similar to the effect occurring due to Kondo type of scattering of conduction electrons with localised moments.

  9. Using CFD Surface Solutions to Shape Sonic Boom Signatures Propagated from Off-Body Pressure

    Science.gov (United States)

    Ordaz, Irian; Li, Wu

    2013-01-01

    The conceptual design of a low-boom and low-drag supersonic aircraft remains a challenge despite significant progress in recent years. Inverse design using reversed equivalent area and adjoint methods have been demonstrated to be effective in shaping the ground signature propagated from computational fluid dynamics (CFD) off-body pressure distributions. However, there is still a need to reduce the computational cost in the early stages of design to obtain a baseline that is feasible for low-boom shaping, and in the search for a robust low-boom design over the entire sonic boom footprint. The proposed design method addresses the need to reduce the computational cost for robust low-boom design by using surface pressure distributions from CFD solutions to shape sonic boom ground signatures propagated from CFD off-body pressure.

  10. Printing transferable components using microstructured elastomeric surfaces with pressure modulated reversible adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Menard, Etienne; Rogers, John A.; Kim, Seok; Carlson, Andrew

    2016-08-09

    In a method of printing a transferable component, a stamp including an elastomeric post having three-dimensional relief features protruding from a surface thereof is pressed against a component on a donor substrate with a first pressure that is sufficient to mechanically deform the relief features and a region of the post between the relief features to contact the component over a first contact area. The stamp is retracted from the donor substrate such that the component is adhered to the stamp. The stamp including the component adhered thereto is pressed against a receiving substrate with a second pressure that is less than the first pressure to contact the component over a second contact area that is smaller than the first contact area. The stamp is then retracted from the receiving substrate to delaminate the component from the stamp and print the component onto the receiving substrate. Related apparatus and stamps are also discussed.

  11. Application of a novel atmospheric pressure plasma fluidized bed in the powder surface modification

    International Nuclear Information System (INIS)

    Chen Guangliang; Chen Shihua; Zhou Mingyan; Feng Wenran; Gu Weichao; Yang Size

    2006-01-01

    A novel atmospheric pressure plasma fluidized bed (APPFB) with one liquid electrode was designed, and its preliminary discharge characteristics were studied. The glow discharge in the APPFB was generated by applying a low power with helium (He) gas, and the plasma gas temperature was no higher than 320 K when the applied power was lower than 11 W. The plasma optical emission spectrum (OES) of the gas mixture consisting of He and hexamethyldisiloxane (HMDSO) was recorded by a UV-visible monochromator. The calcium carbonate powders were modified by APPFB using HMDSO in the He plasma. The powder surface energy was decreased greatly by coating an organosilicon polymer onto the powder surface. This surface modification process changed the wettability of the powder from super-hydrophilicity to super-hydrophobicity, and the contact angle of water on the modified powders surface was greater than 160 0

  12. Simulation of Effective Slip and Drag in Pressure-Driven Flow on Superhydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Yuanding Huang

    2016-01-01

    Full Text Available The flow on superhydrophobic surfaces was investigated using finite element modeling (FEM. Surfaces with different textures like grooves, square pillars, and cylinders immersed in liquid forming Cassie state were modeled. Nonslip boundary condition was assumed at solid-liquid interface while slip boundary condition was supposed at gas-liquid interface. It was found that the flow rate can be affected by the shape of the texture, the fraction of the gas-liquid area, the height of the channel, and the driving pressure gradient. By extracting the effective boundary slip from the flow rate based on a model, it was found that the shape of the textures and the fraction of the gas-liquid area affect the effective slip significantly while the height of the channel and the driving pressure gradient have no obvious effect on effective slip.

  13. Quantitative spatial analysis of the mouse brain lipidome by pressurized liquid extraction surface analysis

    DEFF Research Database (Denmark)

    Almeida, Reinaldo; Berzina, Zane; Christensen, Eva Arnspang

    2015-01-01

    Here we describe a novel surface sampling technique termed pressurized liquid extraction surface analysis (PLESA), which in combination with a dedicated high-resolution shotgun lipidomics routine enables both quantification and in-depth structural characterization of molecular lipid species...... extracted directly from tissue sections. PLESA uses a sealed and pressurized sampling probe that enables the use of chloroform-containing extraction solvents for efficient in situ lipid microextraction with a spatial resolution of 400 μm. Quantification of lipid species is achieved by the inclusion...... of internal lipid standards in the extraction solvent. The analysis of lipid microextracts by nanoelectrospray ionization provides long-lasting ion spray which in conjunction with a hybrid ion trap-orbitrap mass spectrometer enables identification and quantification of molecular lipid species using a method...

  14. DPPC Monolayers Exhibit an Additional Phase Transition at High Surface Pressure

    DEFF Research Database (Denmark)

    Shen, Chen; de la Serna, Jorge B.; Struth, Bernd

    2015-01-01

    Pulmonary surfactant forms a monolayer at the air/aqueous interface within the lung. During the breath process, the surface pressure (Π) periodically varies from ~40mN/m up to ~70mN/m. The film is mechanically stable during this rapid and reversible expansion. Pulmonary surfactant consists of ~90......% of lipid with 10% integrated proteins. Among its lipid compounds, di-palmitoyl-phosphatidylcholine (DPPC) dominates (~45wt%). DPPC is the only known lipid that can be compressed to very high surface pressure (~70mN/m) before its monolayer collapses. Most probably, this feature contributes to the mechanical...... stability of the alveoli monolayer. Still, to the best of our knowledge, some details of the compression isotherm presented here and the related structures of the DPPC monolayer were not studied so far. The liquid-expanded/liquid-condensed phase transition of the DPPC monolayer at ~10mN/m is well known...

  15. Atmospheric pressure surface sampling/ionization techniques for direct coupling of planar separations with mass spectrometry.

    Science.gov (United States)

    Pasilis, Sofie P; Van Berkel, Gary J

    2010-06-18

    Planar separations, which include thin layer chromatography and gel electrophoresis, are in widespread use as important and powerful tools for conducting separations of complex mixtures. To increase the utility of planar separations, new methods are needed that allow in situ characterization of the individual components of the separated mixtures. A large number of atmospheric pressure surface sampling and ionization techniques for use with mass spectrometry have emerged in the past several years, and several have been investigated as a means for mass spectrometric read-out of planar separations. In this article, we review the atmospheric pressure surface sampling and ionization techniques that have been used for the read-out of planar separation media. For each technique, we briefly explain the operational basics and discuss the analyte type for which it is appropriate and some specific applications from the literature. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  16. Expressions to Rayleigh circumferential phase velocity and dispersion relation for a cylindrical surface under mechanical pressure

    Science.gov (United States)

    Sebold, Jean Eduardo; de Lacerda, Luiz Alkimin

    2018-04-01

    This paper describes a substantiated mathematical theory for Rayleigh waves propagated on some types of metal cylinders. More specifically, it presents not only a new way to express the dispersion relation of Rayleigh waves propagated on the cylindrical surface, but also how it can be used to construct a mathematical equation showing that the applied static mechanical pressure affects the shear modulus of the metal cylinder. All steps, required to conclude the process, consider the equation of motion as a function of radial and circumferential coordinates only, while the axial component can be overlooked without causing any problems. Some numerical experiments are done to illustrate the changes in the Rayleigh circumferential phase velocity in a metal cylindrical section due to static mechanical pressure around its external surface.

  17. Stability of skyrmions on curved surfaces in the presence of a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho-Santos, V.L., E-mail: vagson.carvalho@usach.cl [Instituto Federal de Educação, Ciência e Tecnologia Baiano - Campus Senhor do Bonfim, Km 04 Estrada da Igara, 48970-000 Senhor do Bonfim, Bahia (Brazil); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Elias, R.G.; Altbir, D. [Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Fonseca, J.M. [Universidade Federal de Viçosa, Departamento de Física, Avenida Peter Henry Rolfs s/n, 36570-000 Viçosa, MG (Brazil)

    2015-10-01

    We study the stability and energetics associated to skyrmions appearing as excitations on curved surfaces. Using a continuum model we show that the presence of cylindrically radial and azimuthal fields destabilize the skyrmions that appear in the absence of an external field. Weak fields generate fractional skyrmions while strong magnetic fields yield stable 2π-skyrmions, which have their widths diminished by the magnetic field strength. Under azimuthal fields vortex appears as stable state on the curved surface. - Highlights: • Stability of skyrmions on curved surfaces in the presence of a magnetic field. • Weak fields can destabilize skyrmions. • Strong magnetic fields yield the appearing of 2π-skyrmions. • The width of skyrmions is determined by the curvature and magnetic field strength. • Under azimuthal fields vortex appears as stable states.

  18. Influence of atmospheric pressure plasma treatment on surface properties of PBO fiber

    International Nuclear Information System (INIS)

    Zhang Ruiyun; Pan Xianlin; Jiang Muwen; Peng Shujing; Qiu Yiping

    2012-01-01

    Highlights: ► PBO fibers were treated with atmospheric pressure plasmas. ► When 1% of oxygen was added to the plasma, IFSS increased 130%. ► Increased moisture regain could enhance plasma treatment effect on improving IFSS with long treatment time. - Abstract: In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and C=O, O-C=O groups were introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials.

  19. Characterization of an atmospheric pressure air plasma source for polymer surface modification

    Science.gov (United States)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

    An atmospheric pressure air plasma source was generated through dielectric barrier discharge (DBD). It was used to modify polyethyleneterephthalate (PET) surfaces with very high throughput. An equivalent circuit model was used to calculate the peak average electron density. The emission spectrum from the plasma was taken and the main peaks in the spectrum were identified. The ozone density in the down plasma region was estimated by Absorption Spectroscopy. NSF and ARC-ODU

  20. A prospective, in vivo evaluation of two pressure-redistribution surfaces in healthy volunteers using pressure mapping as a quality control instrument .

    Science.gov (United States)

    Miller, Stephannie; Parker, Michael; Blasiole, Nicole; Beinlich, Nancy; Fulton, Judith

    2013-02-01

    Deep tissue injury (DTI) can rapidly evolve into a higher stage pressure ulcer. Use of pressure-redistribution surfaces is a widely accepted practice for the prevention of pressure ulcers in acute care patients, particularly in departments where care processes limit mobility. A 15-year-old patient developed a sacral DTI 24 hours after completion of a lengthy (12- hour) electrophysiology (EP) study and catheter ablation. A root cause analysis (RCA) conducted to investigate the origin of the hospital-acquired suspected DTI prompted a small investigation to evaluate the pressure-distribution properties of the EP lab surface and an OR table pad. Five healthy adult employee volunteers were evaluated in the supine position by placing a sensing mat between the volunteer and the test surface. Interface pressures (on a scale of 0 mm Hg to 100 mm Hg) were captured after a "settling in" time of 4 minutes, and the number of sensors registering very high pressures (above 90 mm Hg) across the surface were recorded. On the OR table pad, zero to six sensors registered >90 mm Hg compared to two to 20 sensors on the EP lab surface. These data, combined with the acquired DTI, initiated a change in EP lab surfaces. Although interface pressure measurements only provide information about one potential support surface characteristic, it can be helpful during an RCA. Studies to compare the effect of support surfaces in all hospital units on patient outcomes are needed.

  1. Planar Pressure Field Determination in the Initial Merging Zone of an Annular Swirling Jet Based on Stereo-PIV Measurements.

    Science.gov (United States)

    Vanierschot, Maarten; Van den Bulck, Eric

    2008-11-28

    In this paper the static pressure field of an annular swirling jet is measured indirectly using stereo-PIV measurements. The pressure field is obtained from numerically solving the Poisson equation, taken into account the axisymmetry of the flow. At the boundaries no assumptions are made and the exact boundary conditions are applied. Since all source terms can be measured using stereo-PIV and the boundary conditions are exact, no assumptions other than axisymmetry had to be made in the calculation of the pressure field. The advantage of this method of indirect pressure measurement is its high spatial resolution compared to the traditional pitot probes. Moreover this method is non-intrusive while the insertion of a pitot tube disturbs the flow. It is shown that the annular swirling flow can be divided into three regimes: a low, an intermediate and a high swirling regime. The pressure field of the low swirling regime is the superposition of the pressure field of the non-swirling jet and a swirl induced pressure field due to the centrifugal forces of the rotating jet. As the swirl increases, the swirl induced pressure field becomes dominant and for the intermediate and high swirling regimes, the simple radial equilibrium equation holds.

  2. Stability of Atmospheric-Pressure Plasma Induced Changes on Polycarbonate Surfaces

    Science.gov (United States)

    Sharma, Rajesh; Holcomb, Edward; Trigwell, Steve

    2006-01-01

    Polycarbonate films are subjected to plasma treatment in a number of applications such as improving adhesion between polycarbonate and silicon alloy in protective and optical coatings. The changes in surface chemistry due to plasma treatment have tendency to revert back. Thus stability of the plasma induced changes on polymer surfaces over desired time period is very important. The objective of this study was to examine the effect of ageing on atmospheric pressure helium-plasma treated polycarbonate (PC) sample as a function of treatment time. The ageing effects were studied over a period of 10 days. The samples were plasma treated for 0.5, 2, 5 and 10 minutes. Contact angle measurements were made to study surface energy changes. Modification of surface chemical structure was examined using, X-ray Photoelectron Spectroscopy (XPS). Contact angle measurements on untreated and plasma treated surfaces were made immediately, 24, 48, 72 and 96 hrs after treatment. Contact angle decreased from 93 deg for untreated sample to 30 deg for sample plasma treated for 10 minutes. After 10 days the contact angles for the 10 minute plasma treated sample increased to 67 deg, but it never reverted back to that of untreated surface. Similarly the O/C ratio increased from 0.136 for untreated sample to 0.321 for 10 minute plasma treated sample indication increase in surface energy.

  3. Surface Modification of Polypropylene Microporous Membrane by Atmospheric-Pressure Plasma Immobilization of N,N-dimethylamino Ethyl Methacrylate

    International Nuclear Information System (INIS)

    Zhong Shaofeng

    2010-01-01

    Surface modification of polypropylene microporous membrane (PPMM) was performed by atmospheric pressure dielectric barrier discharge plasma immobilization of N,N-dimethylamino ethyl methacrylate (DMAEMA). Structural and morphological changes on the membrane surface were characterized by attenuated total reflection-Fourier transform infrared spectroscopy (FT-IR/ATR), X-ray photoelectron spectroscope (XPS) and field emission scanning electron microscopy (FE-SEM). Water contact angles of the membrane surfaces were also measured by the sessile drop method. Results reveal that both the plasma-treating conditions and the adsorbed DMAEMA amount have remarkable effects on the immobilization degree of DMAEMA. Peroxide determination by 1,1-diphenyl-2-picrvlhydrazyl (DPPH) method verifies the exsistence of radicals induced by plasma, which activize the immobilization reaction. Pure water contact angle on the membrane surface decreased with the increase of DMAEMA immobilization degree, which indicates an enhanced hydrophilicity for the modified membranes. The effects of immobilization degrees on pure water fluxes were also measured. It is shown that pure water fluxes first increased with immobilization degree and then decreased. Finally, permeation of bovine serum albumin (BSA) and lysozyme solution were measured to evaluate the antifouling property of the DMAEMA-modified membranes, from which it is shown that both hydrophilicity and electrostatic repulsion are beneficial for membrane antifouling.

  4. Neutron scattering techniques for betaine calcium chloride dihydrate under applied external field (temperature, electric field and hydrostatic pressure)

    International Nuclear Information System (INIS)

    Hernandez, O.

    1997-01-01

    We have studied with neutron scattering techniques betaine calcium chloride dihydrate (BCCD), a dielectric aperiodic crystal which displays a Devil's staircase type phase diagram made up of several incommensurate and commensurate phases, having a range of stability very sensitive to temperature, electric field and hydrostatic pressure. We have measured a global hysteresis of δ(T) of about 2-3 K in the two incommensurate phases. A structural study of the modulated commensurate phases 1/4 and 1/5 allows us to evidence that the atomic modulation functions are anharmonic. The relevance of the modelization of the modulated structure by polar Ising pseudo-spins is then directly established. On the basis of group theory calculation in the four dimensional super-space, we interpret this anharmonic modulation as a soliton regime with respect to the lowest-temperature non modulated ferroelectric phase. The continuous character of the transition to the lowest-temperature non modulated phase and the diffuse scattering observed in this phase are accounted for the presence of ferroelectric domains separated by discommensurations. Furthermore, we have shown that X-rays induce in BCCD a strong variation with time of irradiation of the intensity of satellite peaks, and more specifically for third order ones. This is why the 'X-rays' structural model is found more harmonic than the 'neutron' one. Under electric field applied along the vector b axis, we confirm that commensurate phases with δ = even/odd are favoured and hence are polar along this direction. We have evidenced at 10 kV / cm two new higher order commensurate phases in the phase INC2, corroborating the idea of a 'complete' Devil's air-case phase diagram. A phenomenon of generalized coexistence of phases occurs above 5 kV / cm. We have characterized at high field phase transitions between 'coexisting' phases, which are distinguishable from classical lock-in transitions. Under hydrostatic pressure, our results contradict

  5. Destruction of Invariant Surfaces and Magnetic Coordinates for Perturbed Magnetic Fields

    International Nuclear Information System (INIS)

    Hudson, S.R.

    2003-01-01

    Straight-field-line coordinates are constructed for nearly integrable magnetic fields. The coordinates are based on the robust, noble-irrational rotational-transform surfaces, whose existence is determined by an application of Greene's residue criterion. A simple method to locate these surfaces is described. Sequences of surfaces with rotational-transform converging to low order rationals maximize the region of straight-field-line coordinates

  6. Pressure and Compressibility of Conformal Field Theories from the AdS/CFT Correspondence

    Directory of Open Access Journals (Sweden)

    Brian P. Dolan

    2016-05-01

    Full Text Available The equation of state associated with N = 4 supersymmetric Yang–Mills in four dimensions, for S U ( N in the large N limit, is investigated using the AdS/CFT correspondence. An asymptotically AdS black-hole on the gravity side provides a thermal background for the Yang–Mills theory on the boundary in which the cosmological constant is equivalent to a volume. The thermodynamic variable conjugate to the cosmological constant is a pressure, and the P - V diagram of the quark-gluon plasma is studied. It is known that there is a critical point where the heat capacity diverges, and this is reflected in the isothermal compressibility. Critical exponents are derived and found to be mean field in the large N limit. The same analysis applied to three- and six-dimensional conformal field theories again yields mean field exponents associated with the compressibility at the critical point.

  7. Injection halos of hydrocarbons above oil-gas fields with super-high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtin, V.V.

    1979-09-01

    We studied the origin of injection halos of hydrocarbons above oil-gas fields with anomalously high formation pressures (AHFP). Using fields in Azerbaydzhan and Chechen-Ingushetiya as an example, we demonstrate the effect of certain factors (in particular, faults and zones of increased macro- and micro-jointing) on the morpholoy of the halos. The intensity of micro-jointing (jointing permeability, three-dimensional density of micro-jointing) is directly connected with vertical dimensions of the halos. We measured halos based on transverse profiles across the Khayan-Kort field and studied the distribution of bitumen saturation within the injection halo. Discovery of injection halos during drilling has enabled us to improve the technology of wiring deep-seated exploratory wells for oil and gas in regions with development of AHFP.

  8. Aluminum metal surface cleaning and activation by atmospheric-pressure remote plasma

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz, J., E-mail: jmespadero@uco.es; Bravo, J.A.; Calzada, M.D.

    2017-06-15

    Highlights: • Atmospheric-pressure postdischarges have been applied on aluminium surfaces. • The outer hydrocarbon layer is reduced by the action of the postdischarge. • The treatment promotes the appearance of hydrophilic OH radicals in the surface. • Effectivity for distances up to 5 cm allows for treating irregular surfaces. • Ageing in air due to the disappearance of OH radicals has been reported. - Abstract: The use of the remote plasma (postdischarge) of argon and argon-nitrogen microwave plasmas for cleaning and activating the surface of metallic commercial aluminum samples has been studied. The influence of the nitrogen content and the distance between the treated samples and the end of the discharge on the hydrophilicity and the surface energy has been analyzed by means of the sessile drop technique and the Owens-Wendt method. A significant increase in the hydrophilicity has been noted in the treated samples, together with an increase in the surface energy from values around 37 mJ/m{sup 2} to 77 mJ/m{sup 2}. Such increase weakly depends on the nitrogen content of the discharge, and the effectivity of the treatment extends to distances up to 5 cm from the end of the discharge, much longer than those reported in other plasma-based treatments. The analysis of the treated samples using X-ray photoelectron spectroscopy reveals that such increase in the surface energy takes place due to a reduction of the carbon content and an increase in the amount of OH radicals in the surface. These radicals tend to disappear within 24–48 h after the treatment when the samples are stored in contact with ambient air, resulting in the ageing of the treated surface and a partial retrieval of the hydrophobicity of the surface.

  9. Cytocompatibility evaluation and surface characterization of TiNi deformed by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Awang Shri, Dayangku Noorfazidah, E-mail: AWANGSHRI.Dayangku@nims.go.jp [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Structural Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Tsuchiya, Koichi [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Structural Materials Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Yamamoto, Akiko [Biomaterials Unit, International Center for Material Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-10-01

    Effect of high-pressure torsion (HPT) deformation on biocompatibility and surface chemistry of TiNi was systematically investigated. Ti–50 mol% Ni was subjected to HPT straining for different numbers of turns, N = 0.25, 0.5, 1, 5 and 10 at a rotation speed of 1 rpm. X-ray photoelectron spectroscopy observations after 7 days of cell culture revealed the changes in the surface oxide composition, enrichment of Ti and detection of nitrogen derived from organic molecules in the culture medium. Plating efficiency of L929 cells was slightly increased by HPT deformation though no significant difference was observed. Albumin adsorption was higher in HPT-deformed samples, while vitronectin adsorption was peaked at N = 1. HPT deformation was also found to effectively suppress the Ni ion release from the TiNi samples into the cell culture medium even after the low degree of deformation at N = 0.25. - Highlights: • Nanostructured Ti–50 mol%Ni alloy was produced using high-pressure torsion. • HPT deformation improved L929 growth on TiNi samples. • Changes in surface chemistry were observed in HPT deformed samples. • Protein adsorption behavior was influenced by the surface chemistry. • Ni ion release was suppressed in HPT deformed samples.

  10. Absolute local sea surface in the Vanuatu Archipelago from GPS, satellite altimetry and pressure gauge data

    Science.gov (United States)

    Cheng, K. K.; Ballu, V.; Bouin, M.; Calmant, S.; Shum, C.

    2004-12-01

    Water height measurements provided by seafloor tide gauges are a combination of sea level variation and local ground motion. Both signals are of scientific interest, but they must be separated in order to be useful. A reliable estimation of the vertical ground motion is important in very seismically areas such as the Pacific Ocean rim. One promising method to separate the two contributions is to use satellite altimetry which gives absolute water height that is independent of the local ground motion. However, the altimeter data must be calibrated using ground truth measurements. Once different components of the signal are separated, bottom pressure gauges can be used to detect vertical movements of the seafloor. The Vanuatu Archipelago is part of the Pacific "ring of fire", where plates are quickly converging. In this area, movements are very rapid and the seismic activity is intense, which gives a good opportunity to study deformation and seismic cycle. To get an integrate picture of vertical deformation over one plate and between the two plates, one needs to be able to monitor vertical movements on both underwater and emerged areas. We conducted an experiment in this area to compare measurements from bottom pressure gauges located beneath altimetry satellite tracks with sea surface altitude measurements from GPS. Two bottom pressure gauge are immerged since Nov. 1999 in this region. In order to perform absolute calibration for multiple satellite altimeters that overfly the region, we conducted 2 campaigns of GPS measurements of instantaneous sea surface height onboard the R/V Alis and using a GPS buoy. We present results of GPS computations for the March 2003 and March 2004 campaigns. These sea level GPS measurements are compared with multiple altimeter-measured sea surface heights, and sampling differences and high frequency variations were removed using continuous pressure gauge data. The observed discrepancies are likely to be explained by local geoid

  11. Development of an Organosilicon-Based Superhydrophobic/Icephobic Surface Using an Atmospheric Pressure Plasma Jet =

    Science.gov (United States)

    Asadollahi, Siavash

    During the past few decades, plasma-based surface treatment methods have gained a lot of interest in various applications such as thin film deposition, surface etching, surface activation and/or cleaning, etc. Generally, in plasma-based surface treatment methods, high-energy plasma-generated species are utilized to modify the surface structure or the chemical composition of a substrate. Unique physical and chemical characteristics of the plasma along with the high controllability of the process makes plasma treatment approaches very attractive in several industries. Plasma-based treatment methods are currently being used or investigated for a number of practical applications, such as adhesion promotion in auto industry, wound management and cancer treatment in biomedical industry, and coating development in aerospace industry. In this study, a two-step procedure is proposed for the development of superhydrophobic/icephobic coatings based on atmospheric-pressure plasma treatment of aluminum substrates using air and nitrogen plasma. The effects of plasma parameters on various surface properties are studied in order to identify the optimum conditions for maximum coating efficiency against icing and wetting. In the first step, the interactions between air or nitrogen plasma and the aluminum surface are studied. It is shown that by reducing jet-to-substrate distance, air plasma treatment, unlike nitrogen plasma treatment, is capable of creating micro-porous micro-roughened structures on the surface, some of which bear a significant resemblance to the features observed in laser ablation of metals with short and ultra-short laser pulses. The formation of such structures in plasma treatment is attributed to a transportation of energy from the jet to the surface over a very short period of time, in the range of picoseconds to microseconds. This energy transfer is shown to occur through a streamer discharge from the rotating arc source in the jet body to a close proximity of

  12. Vector Magnetic Fields, Sub surface Stresses and Evolution of ...

    Indian Academy of Sciences (India)

    tribpo

    Abstract. Observations of the strength and spatial distribution of vector magnetic fields in active regions have revealed several fundamental properties of the twist of their magnetic fields. First, the handedness of this twist obeys a hemispheric rule: left handed in the northern hemis phere, right handed in the southern. Second ...

  13. A coupled surface/subsurface flow model accounting for air entrapment and air pressure counterflow

    DEFF Research Database (Denmark)

    Delfs, Jens Olaf; Wang, Wenqing; Kalbacher, Thomas

    2013-01-01

    the mass exchange between compartments. A benchmark test, which is based on a classic experimental data set on infiltration excess (Horton) overland flow, identified a feedback mechanism between surface runoff and soil air pressures. Our study suggests that air compression in soils amplifies surface runoff......This work introduces the soil air system into integrated hydrology by simulating the flow processes and interactions of surface runoff, soil moisture and air in the shallow subsurface. The numerical model is formulated as a coupled system of partial differential equations for hydrostatic (diffusive...... wave) shallow flow and two-phase flow in a porous medium. The simultaneous mass transfer between the soil, overland, and atmosphere compartments is achieved by upgrading a fully established leakance concept for overland-soil liquid exchange to an air exchange flux between soil and atmosphere. In a new...

  14. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    Science.gov (United States)

    Carr,; Jeffrey, W [Livermore, CA

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  15. Streams and magnetic fields in surface layers of Ap-stars

    International Nuclear Information System (INIS)

    Dolginov, A.Z.; Urpin, V.A.

    1978-01-01

    Magnetic field generation of Ap-stars is considered. It is shown that in the surface layers of Ap-stars inhomogeneity of chemical composition produces a strong magnetic field. Velocities of possible circulation of stellar matter are estimated. It is shown that circulation does not prevent the process of the magnetic field generation. It needs the order of million years, for arranging the stationary magnetic field in surface layers

  16. Surface modification of polyimide (PI) film using water cathode atmospheric pressure glow discharge plasma

    International Nuclear Information System (INIS)

    Zheng Peichao; Liu Keming; Wang Jinmei; Dai Yu; Yu Bin; Zhou Xianju; Hao Honggang; Luo Yuan

    2012-01-01

    Highlights: ► Equipment called water cathode atmospheric pressure glow discharge was used to improve the hydrophilicity of polyimide films. ► The data shows good homogeneity and the variation trends of contact angles are different for polar and non-polar testing liquids. ► The thickness of liquid layer plays an important role in plasma processing and directly affects the treatment effect. ► Surface hydrophilicity after plasma treatment is improved partly due to the increase in the roughness. ► The hydrophilicity of polyimide films is still better than untreated ones after long-term storage. - Abstract: The industrial use of polyimide film is limited because of undesirable properties such as poor wettability. In the present paper, a new kind of equipment called water cathode atmospheric pressure glow discharge was used to improve the surface properties of polyimide films and made them useful to technical applications. The changes in hydrophilicity of modified polyimide film surfaces were investigated by contact angle, surface energy and water content measurements as a function of treatment time. The results obtained show good treatment homogeneity and that the variation trends of contact angles are different for polar and non-polar testing liquids, while surface energy and water content are significantly enhanced with the increase of treatment time until they achieve saturated values after 60 s plasma treatment. Also, the thickness of liquid layer plays an important role in plasma processing and directly affects the treatment effect. Changes in morphology of polyimide films were analyzed by atomic force microscope and the results indicate that surface hydrophilicity after plasma treatment are improved partly due to the increase in the roughness. In addition, polyimide films treated by plasma are subjected to an ageing process to determine the durability of plasma treatment. It is found that the hydrophilicity is still better than untreated ones though the

  17. Effect of nanoscale surface texture on the contact-pressure-dependent conduction characteristics of a carbon-nanotube thin-film tactile pressure sensor

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Chaehyun; Lee, Kunhak; Choi, Eunsuk; Kim, Ahsung; Kim, Jinoh; Lee, Seungbeck [Hanyang University, Seoul (Korea, Republic of)

    2011-01-15

    We report on a novel tactile pressure sensor structure that transfers the vertical pressure applied to the sample's surface to lateral strain in the carbon-nanotube thin film embedded in an elastomer by using a 'wavy' structured substrate contact surface. When pressure was applied to the poly(dimethylsiloxane) (PDMS) surface, it was transferred to a carbon-nanotube thin film (CNTF) underneath, where it stretched to conform to the wavy substrate surface. This resulted in an elongation, or lateral strain, in the CNTF layer, their reducing its conductance. The measurements showed that with an applied vertical pressure of 30 kPa, a 15% reduction in conductance was achieved with only a 500-nm deflection in the CNTF, and repeatedly applied pressures for 3,600 cycles (12 hours) resulted in only a 2% reduction in sensitivity, demonstrating the their film's high sensitivity and reliability. The mechanical stability and high sensitivity of the CNTF/PDMS hybrid with wavy substrate structures may make possible applications to future tactile pressure sensors.

  18. Pressure changes and their effects on the Cerro Prieto geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Bermejo M, F.J.; Navarro O, F.X.; Esquer P, C.A.; Castillo B, F.; de la Cruz D, F.C.

    1981-01-01

    Continuous extraction of the water-steam mixture at the field has been increasing to fulfill the steam requirements of the power plant. As a result, pressure declines have been observed in the producing strata in all of the wells, as well as in the geothermal reservoir as a whole. Anomalous behavior that has been observed in the wells' hydraulic columns in most cases is due to the interconnection of the various strata penetrated by the well. When this occurs, unbalanced hydraulic pressures cause the movement of fluids between the strata. As an example of this hydraulic imbalance causing the flow of fluids from an upper to a lower zone, well Nuevo Leon 1 where this effect occurs between regions 600 m apart was chosen.

  19. Capillary pressure in a porous medium with distinct pore surface and pore volume fractal dimensions.

    Science.gov (United States)

    Deinert, M R; Dathe, A; Parlange, J-Y; Cady, K B

    2008-02-01

    The relationship between capillary pressure and saturation in a porous medium often exhibits a power-law dependence. The physical basis for this relation has been substantiated by assuming that capillary pressure is directly related to the pore radius. When the pore space of a medium exhibits fractal structure this approach results in a power-law relation with an exponent of 3-D(v), where D(v) is the pore volume fractal dimension. However, larger values of the exponent than are realistically allowed by this result have long been known to occur. Using a thermodynamic formulation for equilibrium capillary pressure we show that the standard result is a special case of the more general exponent (3-D(v))(3-D(s)) where D(s) is the surface fractal dimension of the pores. The analysis reduces to the standard result when D(s)=2, indicating a Euclidean relationship between a pore's surface area and the volume it encloses, and allows for a larger value for the exponent than the standard result when D(s)>2 .

  20. Photodetachment of negative ion in a gradient electric field near a metal surface

    International Nuclear Information System (INIS)

    Liu Tian-Qi; Wang De-Hua; Han Cai; Liu Jiang; Liang Dong-Qi; Xie Si-Cheng

    2012-01-01

    Based on closed-orbit theory, the photodetachment of H − in a gradient electric field near a metal surface is studied. It is demonstrated that the gradient electric field has a significant influence on the photodetachment of negative ions near a metal surface. With the increase of the gradient of the electric field, the oscillation in the photodetachment cross section becomes strengthened. Besides, in contrast to the photodetachment of H − near a metal surface in a uniform electric field, the oscillating amplitude and the oscillating region in the cross section of a gradient electric field also become enlarged. Therefore, we can use the gradient electric field to control the photodetachment of negative ions near a metal surface. We hope that our results will be useful for understanding the photodetachment of negative ions in the vicinity of surfaces, cavities, and ion traps. (atomic and molecular physics)

  1. Surface plasmon field enhancements in deterministic aperiodic structures.

    Science.gov (United States)

    Shugayev, Roman

    2010-11-22

    In this paper we analyze optical properties and plasmonic field enhancements in large aperiodic nanostructures. We introduce extension of Generalized Ohm's Law approach to estimate electromagnetic properties of Fibonacci, Rudin-Shapiro, cluster-cluster aggregate and random deterministic clusters. Our results suggest that deterministic aperiodic structures produce field enhancements comparable to random morphologies while offering better understanding of field localizations and improved substrate design controllability. Generalized Ohm's law results for deterministic aperiodic structures are in good agreement with simulations obtained using discrete dipole method.

  2. Rough-Surface-Enabled Capacitive Pressure Sensors with 3D Touch Capability.

    Science.gov (United States)

    Lee, Kilsoo; Lee, Jaehong; Kim, Gwangmook; Kim, Youngjae; Kang, Subin; Cho, Sungjun; Kim, SeulGee; Kim, Jae-Kang; Lee, Wooyoung; Kim, Dae-Eun; Kang, Shinill; Kim, DaeEun; Lee, Taeyoon; Shim, Wooyoung

    2017-11-01

    Fabrication strategies that pursue "simplicity" for the production process and "functionality" for a device, in general, are mutually exclusive. Therefore, strategies that are less expensive, less equipment-intensive, and consequently, more accessible to researchers for the realization of omnipresent electronics are required. Here, this study presents a conceptually different approach that utilizes the inartificial design of the surface roughness of paper to realize a capacitive pressure sensor with high performance compared with sensors produced using costly microfabrication processes. This study utilizes a writing activity with a pencil and paper, which enables the construction of a fundamental capacitor that can be used as a flexible capacitive pressure sensor with high pressure sensitivity and short response time and that it can be inexpensively fabricated over large areas. Furthermore, the paper-based pressure sensors are integrated into a fully functional 3D touch-pad device, which is a step toward the realization of omnipresent electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Fermi Surface, Pressure-Induced Antiferromagnetic Order, and Superconductivity in FeSe

    Science.gov (United States)

    Ishizuka, Jun; Yamada, Takemi; Yanagi, Yuki; Ōno, Yoshiaki

    2018-01-01

    The pressure dependence of the structural (Ts), antiferromagnetic (Tm), and superconducting (Tc) transition temperatures in FeSe is investigated on the basis of the 16-band d-p model. At ambient pressure, a shallow hole pocket disappears due to the correlation effect, as observed in the angular-resolved photoemission spectroscopy (ARPES) and quantum oscillation (QO) experiments, resulting in the suppression of the antiferromagnetic order, in contrast to the other iron pnictides. The orbital-polarization interaction between the Fe d orbital and Se p orbital is found to drive the ferro-orbital order responsible for the structural transition without accompanying the antiferromagnetic order. The pressure dependence of the Fermi surfaces is derived from the first-principles calculation and is found to well account for the opposite pressure dependences of Ts and Tm, around which the enhanced orbital and magnetic fluctuations cause the double-dome structure of the eigenvalue λ in the Eliashberg equation, as consistent with that of Tc in FeSe.

  4. 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

  5. The Ngatamariki Geothermal Field, NZ: Surface Manifestations - Past and Present

    Energy Technology Data Exchange (ETDEWEB)

    Brotheridge, J.M.A.; Browne, P.R.L.; Hochstein, M.P.

    1995-01-01

    The Ngatamariki geothermal field, located 7 km south of Orakeikorako, discharges dilute chloride-bicarbonate waters of almost neutral pH from springs mostly on the margins of the field. Rhyolite tuffs in the northwestern part of the field are weakly silicified, probably due to their having reacted with heated groundwaters. Sinter deposits are common at Ngatamariki but are mostly relict from former activity. In 1994, the natural heat loss from the field was 30 {+-} 5 MW{sub thermal}. There has been a shift of thermal activity southward over the past 60 years; the changes were recognized by comparing air photographs taken in 1941 and 1991. In 1948, a hydrothermal eruption deposited breccia around its crater, which is now occupied by a pool at 52.5 C. Another pool at 88 C, first noticed in 1993, deposits a mixture of silica and calcite.

  6. Field emission from the surface of highly ordered pyrolytic graphite

    Czech Academy of Sciences Publication Activity Database

    Knápek, Alexandr; Sobola, D.; Tománek, P.; Pokorná, Zuzana; Urbánek, Michal

    2017-01-01

    Roč. 395, FEB 15 (2017), s. 157-161 ISSN 0169-4332 R&D Projects: GA TA ČR(CZ) TE01020118 Institutional support: RVO:68081731 Keywords : field emission * HOPG * scanning electron microscopy * scanning near-field optical microscopy Subject RIV: JA - Electron ics ; Optoelectronics, Electrical Engineering OBOR OECD: Nano-processes (applications on nano-scale) Impact factor: 3.387, year: 2016

  7. Deriving the geomagnetically induced electric field at the Earth's surface from the time derivative of the vertical magnetic field

    Science.gov (United States)

    Vanhamäki, Heikki; Viljanen, Ari; Pirjola, Risto; Amm, Olaf

    2013-09-01

    We present a new method for estimating the geomagnetically induced electric field at the Earth's surface directly from the time derivative of the vertical magnetic field, without any need for additional information about the Earth's electric conductivity. This is a simplification compared to the presently used calculation methods, which require both the magnetic variation field and ground conductivity model as input data. The surface electric field is needed e.g. in modeling Geomagnetically Induced Currents (GIC) that flow in man-made conductor systems, such as gas and oil pipelines or high-voltage power grids. We solve the induced electric field directly from Faraday's law, by representing the magnetic variation field in terms of external equivalent current and taking time derivative of the associated vector potential. This gives an approximative solution, where the divergence-free part of the electric field is reproduced accurately (at least in principle), but the curl-free part related to lateral variations in ground conductivity is completely neglected. We test the new calculation method with several realistic models of typical ionospheric current systems, as well as actual data from the Baltic Electromagnetic Array Research (BEAR) network. We conclude that the principle of calculating the (divergence-free part of the) surface electric field from time derivative of the vertical magnetic field is sound, and the method works reasonably well also in practice. However, practical applications may be rather limited as the method seems to require data from a quite dense and spatially extended magnetometer network.

  8. Consumer acceptance of high-pressure processing and pulsed-electric-field

    DEFF Research Database (Denmark)

    Olsen, Nina Veflen; Grunert, Klaus G.; Sonne, Anne-Mette

    2010-01-01

    New products and new processing techniques are continuously developed in the food industry. While food scientists may focus on the technical novelty and applaud the progress of science, consumers are often conservative and sceptical towards changes. The advantages that a new processing technology...... has to offer, do not necessarily guarantee the success of a product in the market place. Consumer acceptance depends on whether consumers perceive that there are specific benefits associated with the product. This review focuses specifically on how high-pressure processing (HPP) and pulsed......-electric-field (PEF) technologies and products produced by means of these novel technologies are perceived by consumers....

  9. Surface reconstruction of GaAs(001) nitrided under the controlled As partial pressure [rapid communication

    Science.gov (United States)

    Imayoshi, Takahiro; Oigawa, Haruhiro; Shigekawa, Hidemi; Tokumoto, Hiroshi

    2003-08-01

    Under the controlled As partial pressure, the nitridation process of GaAs(0 0 1)-(2 × 4) surface was studied using a scanning tunneling microscope (STM) combined with an electron cyclotron resonance plasma-assisted molecular beam epitaxy system. With either prolonging the nitridation time or decreasing the As partial pressure, the previously reported (3 × 3) structure with two dimers per surface cell ((3 × 3)-2D) was found to progressively convert into a new (3 × 3) structure characterized by one dimer per surface cell ((3 × 3)-1D). Reversely the exposure to arsenic transformed the structure from (3 × 3)-1D to (3 × 3)-2D, suggesting that the topmost layer is composed of As 2-dimers. Based on these STM images together with the X-ray photoelectron spectroscopy data, we propose the new As 2-dimer coverage models to explain both (3 × 3)-1D and -2D structures involving the exchange reaction of arsenic with nitrogen in the subsurface region of GaAs.

  10. Electric field determination in streamer discharges in air at atmospheric pressure

    International Nuclear Information System (INIS)

    Bonaventura, Z; Bourdon, A; Celestin, S; Pasko, V P

    2011-01-01

    The electric field in streamer discharges in air can be easily determined by the ratio of luminous intensities emitted by N 2 (C 3 Π u ) and N 2 + (B 2 Σ u + ) if the steady-state assumption of the emitting states is fully justified. At ground pressure, the steady-state condition is not fulfilled and it is demonstrated that its direct use to determine the local and instantaneous peak electric field in the streamer head may overestimate this field by a factor of 2. However, when spatial and time-integrated optical emissions (OEs) are considered, the reported results show that it is possible to formulate a correction factor in the framework of the steady-state approximation and to accurately determine the peak electric field in an air discharge at atmospheric pressure. A correction factor is defined as Γ = E s /E e , where E e is the estimated electric field and E s is the true peak electric field in the streamer head. It is shown that this correction stems from (i) the shift between the location of the peak electric field and the maximum excitation rate for N 2 (C 3 Π u ) and N 2 + (B 2 Σ u + ) as proposed by Naidis (2009 Phys. Rev. E 79 057401) and (ii) from the cylindrical geometry of the streamers as stated by Celestin and Pasko (2010 Geophys. Res. Lett. 37 L07804). For instantaneous OEs integrated over the whole radiating plasma volume, a correction factor of Γ ∼ 1.4 has to be used. For time-integrated OEs, the reported results show that the ratio of intensities can be used to derive the electric field in discharges if the time of integration is sufficiently long (i.e. at least longer than the longest characteristic lifetime of excited species) to have the time to collect all the light from the emitting zones of the streamer. For OEs recorded using slits (i.e. a window with a small width but a sufficiently large radial extension to contain the total radial extension of the discharge) the calculated correction factor is Γ ∼ 1.4. As for OEs observed

  11. FLUID-STRUCTURE INTERACTION IN A U-TUBE WITH SURFACE ROUGHNESS AND PRESSURE DROP

    Directory of Open Access Journals (Sweden)

    GYUN-HO GIM

    2014-10-01

    Full Text Available In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI. The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency of pump, and fluid-structure interaction.

  12. Static Air Support Surfaces to Prevent Pressure Injuries: A Multicenter Cohort Study in Belgian Nursing Homes.

    Science.gov (United States)

    Serraes, Brecht; Beeckman, Dimitri

    2016-01-01

    The aim of this study was to investigate the incidence and risk factors for developing pressure injuries (PIs) in patients placed on a static air support surfaces: mattress overlay, heel wedge, and seat cushion. Multicenter cohort study. The sample comprised 176 residents; their mean age was 87 (SD = 6.76) years; their mean Braden Scale score was 14 (SD = 2.54). The study was performed on a convenience sample of 6 nursing homes in Belgium. Data were collected on 23 care units. The primary outcome measure, cumulative PI incidence (category [stage] II-IV) over a 30-day observation period, was calculated. Pressure injury occurrence was defined according to the 2014 European and US National Pressure Injury Advisory panels, Pan Pacific Pressure Injury Alliance classification system. The PI incidence for category (stage) II-IV was 5.1%. Six residents (3.4%) developed a category II PI, and 3 (1.7%) developed a category III PI; no category IV ulcers occurred. No significant risk factors for category II-IV PIs were identified using multivariate logistic regression. Time of sitting in a chair was found to be a risk factor for development of nonblanchable erythema (category I PI) (odds ratio = 21.608; 95% confidence interval [CI], 20.510-22.812; P = .013). The median time to develop a category II-IV PI was 16 days (interquartile range = 2-26). The interrater reliability between the observations of the researcher and nurses on-site was almost perfect (0.86; 95% CI, 0.81-0.91). We found a low incidence of PIs when using a static air overlay mattress for patients at risk in a nursing home population. Static air support surfaces, alongside patient-tailored patient repositioning protocols, should be considered to prevent PIs in this patient population.

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

    Science.gov (United States)

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

    2016-01-01

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

  14. Investigation of surface treatment of conductive wire in cylindrical atmospheric pressure plasmas

    International Nuclear Information System (INIS)

    Ye Rubin; Kagohashi, Tsutomu; Zheng Wei

    2009-01-01

    Polyethylene insulated electric wire was treated in He and Ar dielectric barrier discharge atmospheric pressure plasmas generated in a quartz tube wound with tubular electrodes. The wire was put penetrating through the high voltage and the grounded electrodes, improving the discharge and facilitating uniform surface treatment. In this work, the influences of conductivity of the wire on the effects of surface treatment and discharge behavior were investigated. Surface properties of the wire samples were analyzed by means of surface energy measurement and X-ray photoelectron spectroscopy. In order to reveal the mechanism for treating the conductive wire, I-V discharge waveforms were measured and time-resolved plasma images were taken. It was demonstrated that the conductive wire was involved in the discharge process, reducing the breakdown voltage significantly and enhancing the discharge. It shows that the discharge mode was strongly dependent on the conductivity of a wire. Intensive surface discharges developed along the conductive wire were found to be mainly responsible for noticeable improvement in the treatment effect.

  15. Ambient pressure dried tetrapropoxysilane-based silica aerogels with high specific surface area

    Science.gov (United States)

    Parale, Vinayak G.; Han, Wooje; Jung, Hae-Noo-Ree; Lee, Kyu-Yeon; Park, Hyung-Ho

    2018-01-01

    In the present paper, we report the synthesis of tetrapropoxysilane (TPOS)-based silica aerogels with high surface area and large pore volume. The silica aerogels were prepared by a two-step sol-gel process followed by surface modification via a simple ambient pressure drying approach. In order to minimize drying shrinkage and obtain hydrophobic aerogels, the surface of the alcogels was modified using trichloromethylsilane as a silylating agent. The effect of the sol-gel compositional parameters on the polymerization of aerogels prepared by TPOS, one of the precursors belonging to the Si(OR)4 family, was reported for the first time. The oxalic acid and NH4OH concentrations were adjusted to achieve good-quality aerogels with high surface area, low density, and high transparency. Controlling the hydrolysis and condensation reactions of the TPOS precursor turned out to be the most important factor to determine the pore characteristics of the aerogel. Highly transparent aerogels with high specific surface area (938 m2/g) and low density (0.047 g/cm3) could be obtained using an optimized TPOS/MeOH molar ratio with appropriate concentrations of oxalic acid and NH4OH.

  16. 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.

  17. [Measurements of surface ocean carbon dioxide partial pressure during WOCE]. Summary of research progress

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-31

    This paper discusses the research progress of the second year of research under ``Measurement of Surface Ocean Carbon Dioxide Partial Pressure During WOCE`` and proposes to continue measurements of underway pCO{sub 2}. During most of the first year of this grant, our efforts to measure pCO{sub 2} on WOCE WHP legs were frustrated by ship problems. The R/V Knorr, which was originally scheduled to carry out the first work on WHP lines P19 and P16 in the southeastem Pacific during the 1990-91 austral summer, was delayed in the shipyard during her mid-life refit for more than a year. In the interim, the smaller R/V Thomas Washington, was pressed into service to carry out lower-latitude portions of WHP lines P16 and P17 during mid-1991 (TUNES Expedition). We installed and operated our underway chromatographic system on this expedition, even though space and manpower on this smaller vessel were limited and no one from our group would be aboard any of the 3 WHP expedition legs. The results for carbon dioxide and nitrous oxide are shown. A map of the cruise track is shown for each leg, marked with cumulative distance. Following each track is a figure showing the carbon dioxide and nitrous oxide results as a function of distance along this track. The results are plotted as dry-gas mole fractions (in ppm and ppb, respectively) in air and in gas equilibrated with surface seawater at a total pressure equal to the barometric pressure. The air data are plotted as a 10-point running mean, and appear as a roughly horizontal line. The seawater data are plotted as individual points, using a 5-point Gaussian smoother. Equal values Of xCO{sub 2} in air and surface seawater indicate air-sea equilibrium.

  18. Monte Carlo analysis of field-dependent electron avalanche coefficients in nitrogen at atmospheric pressure

    Science.gov (United States)

    Nguyen, H. K.; Mankowski, J.; Dickens, J. C.; Neuber, A. A.; Joshi, R. P.

    2017-12-01

    Calculations of electron impact ionization of nitrogen gas at atmospheric pressure are presented based on the kinetic Monte Carlo technique. The emphasis is on energy partitioning between primary and secondary electrons, and three different energy sharing schemes have been evaluated. The ionization behavior is based on Wannier's classical treatment. Our Monte Carlo results for the field-dependent drift velocities match the available experimental data. More interestingly, the field-dependent first Townsend coefficient predicted by the Monte Carlo calculations is shown to be in close agreement with reported data for E/N values ranging as high as 4000 Td, only when a random assignment of excess energies between the primary and secondary particles is used.

  19. Theory of aberration fields for general optical systems with freeform surfaces.

    Science.gov (United States)

    Fuerschbach, Kyle; Rolland, Jannick P; Thompson, Kevin P

    2014-11-03

    This paper utilizes the framework of nodal aberration theory to describe the aberration field behavior that emerges in optical systems with freeform optical surfaces, particularly φ-polynomial surfaces, including Zernike polynomial surfaces, that lie anywhere in the optical system. If the freeform surface is located at the stop or pupil, the net aberration contribution of the freeform surface is field constant. As the freeform optical surface is displaced longitudinally away from the stop or pupil of the optical system, the net aberration contribution becomes field dependent. It is demonstrated that there are no new aberration types when describing the aberration fields that arise with the introduction of freeform optical surfaces. Significantly it is shown that the aberration fields that emerge with the inclusion of freeform surfaces in an optical system are exactly those that have been described by nodal aberration theory for tilted and decentered optical systems. The key contribution here lies in establishing the field dependence and nodal behavior of each freeform term that is essential knowledge for effective application to optical system design. With this development, the nodes that are distributed throughout the field of view for each aberration type can be anticipated and targeted during optimization for the correction or control of the aberrations in an optical system with freeform surfaces. This work does not place any symmetry constraints on the optical system, which could be packaged in a fully three dimensional geometry, without fold mirrors.

  20. Improvement of field emission from screen-printed carbon nanotubes by He/(N2,Ar) atmospheric pressure plasma treatment

    International Nuclear Information System (INIS)

    Kyung, S. J.; Park, J. B.; Lee, J. H.; Yeom, G. Y.

    2006-01-01

    A screen-printed carbon nanotube (CNT) paste for applications to field emission emitters was treated with He, He/Ar, and He/N 2 atmospheric pressure plasmas. The effect of the different plasma treatments on the field emission characteristics of the screen-printed CNTs was investigated. The atmospheric pressure plasma applied to the screen-printed CNT paste for 10 s resulted in a reduction in the turn-on electric field. In particular, the application of a He/N 2 plasma treatment decreased the turn-on electric field from 3.13 to 1.29 V/μm and increased the field enhancement factor from 737 to 2775 after the treatment. These results suggest that an adequate atmospheric pressure plasma treatment of screen-printed CNTs can be effective in enhancing the field emission properties

  1. Laser-Driven Ultrafast Field Propagation on Solid Surfaces

    Science.gov (United States)

    Quinn, K.; Wilson, P. A.; Cecchetti, C. A.; Ramakrishna, B.; Romagnani, L.; Sarri, G.; Lancia, L.; Fuchs, J.; Pipahl, A.; Toncian, T.; Willi, O.; Clarke, R. J.; Neely, D.; Notley, M.; Gallegos, P.; Carroll, D. C.; Quinn, M. N.; Yuan, X. H.; McKenna, P.; Liseykina, T. V.; Macchi, A.; Borghesi, M.

    2009-05-01

    The interaction of a 3×1019W/cm2 laser pulse with a metallic wire has been investigated using proton radiography. The pulse is observed to drive the propagation of a highly transient field along the wire at the speed of light. Within a temporal window of 20 ps, the current driven by this field rises to its peak magnitude ˜104A before decaying to below measurable levels. Supported by particle-in-cell simulation results and simple theoretical reasoning, the transient field measured is interpreted as a charge-neutralizing disturbance propagated away from the interaction region as a result of the permanent loss of a small fraction of the laser-accelerated hot electron population to vacuum.

  2. Study on the reforming of alcohols in a surface wave discharge (SWD) at atmospheric pressure

    International Nuclear Information System (INIS)

    Jimenez, M; Yubero, C; Calzada, M D

    2008-01-01

    Surface wave plasma at atmospheric pressure has been used to produce the decomposition of the alcohol molecules introduced into it, in order to obtain hydrogen. Four alcohols, methanol, ethanol, propanol and butanol, have been used for this purpose. Optical emission spectroscopy was the tool used to analyse the radiation emitted by the plasma. Hydrogen atoms and other species such as C 2 and CH in alcohols have been detected but no CO molecular bands. Also, a mass spectrometer has been used in order to detect molecular hydrogen production in methanol decomposition

  3. Electromagnetic Fields at the Surface of Human-Body Cylinders

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper

    2016-01-01

    The electromagnetic fields around an infinitely long cylinder with different material parameters are analyzed. The cylinder is modeled as muscle, skin, fat, and perfect electric conductor respectively. The cylinder is illuminated by a plane wave incident from different angles and with both...... transverse electric and transverse magnetic polarization. The results show that the material assumption when modeling the human body as a homogeneous material is very important. Furthermore, it is shown that one assumption might lead to higher fields for a specific polarization, angle of incidence...

  4. Coupling between magnetic field and curvature in Heisenberg spins on surfaces with rotational symmetry

    International Nuclear Information System (INIS)

    Carvalho-Santos, Vagson L.; Dandoloff, Rossen

    2012-01-01

    We study the nonlinear σ-model in an external magnetic field applied on curved surfaces with rotational symmetry. The Euler–Lagrange equations derived from the Hamiltonian yield the double sine-Gordon equation (DSG) provided the magnetic field is tuned with the curvature of the surface. A 2π skyrmion appears like a solution for this model and surface deformations are predicted at the sector where the spins point in the opposite direction to the magnetic field. We also study some specific examples by applying the model on three rotationally symmetric surfaces: the cylinder, the catenoid and the hyperboloid.

  5. Oxygen Plasma Treatment of Rubber Surface by the Atmospheric Pressure Cold Plasma Torch

    DEFF Research Database (Denmark)

    Lee, Bong-ju; Kusano, Yukihiro; Kato, Nobuko

    1997-01-01

    adhesive. The adhesion property was improved by treatment of the rubber compound with plasma containing oxygen radicals. Physical and chemical changes of the rubber surface as a result of the plasma treatment were analyzed by field emission scanning electron microscopy (FE-SEM) and fourier transform......A new application of the atmospheric cold plasma torch has been investigated. Namely, the surface treatment of an air-exposed vulcanized rubber compound. The effect of plasma treatment was evaluated by the bondability of the treated rubber compound with another rubber compound using a polyurethane...

  6. Field evidences of secondary surface ruptures occurred during the ...

    Indian Academy of Sciences (India)

    Some rock slides of several tens of meters in size that obviously require significantly high ground shaking were also developed on steep fault scarps. The orientation of the principal stress tensor as deduced from the surface rupture of the Eskisehir earthquake displays clear inconsistency with the geometry of prominent ...

  7. Field verification of ADCP surface gravity wave elevation spectra

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Peters, H.C.; Schroevers, M.

    2007-01-01

    Acoustic Doppler current profilers (ADCPs) can measure orbital velocities induced by surface gravity waves, yet the ADCP estimates of these velocities are subject to a relatively high noise level. The present paper introduces a linear filtration technique to significantly reduce the influence of

  8. Field evidences of secondary surface ruptures occurred during the ...

    Indian Academy of Sciences (India)

    The orientation of the principal stress tensor as deduced from the surface rupture of the Eskisehir earthquake ... history extended back to late Oligocene exhuma- tion of the Uludag massif (Okay et al 2008) and the ensuing ... accepted this view estimating stress directions from slip measurements in the main bounding faults.

  9. Phase Field Theory and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic

    Science.gov (United States)

    2014-08-01

    Phase Field Theory and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic by John D Clayton ARL-RP...Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic John D Clayton Weapons and Materials Research Directorate, ARL...and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  10. Pressure dependence of crystal field splitting in Pr pnictides and chalcogenides

    International Nuclear Information System (INIS)

    Schirber, J.E.; Weaver, H.T.; Ginley, D.S.

    1978-01-01

    We have measured the pressure dependence of the Pr nuclear magnetic resonance shift in PrN, PrP, PrSb, PrAs, PrS and PrSe. The shifts in all the pnictides increase while in the chalcogenides the shifts decrease with pressure. The rare earth frequency shift is inversely proportional to the crystal field splitting in the context of the point charge model (PCM) so a decrease would be expected for all of these materials at a rate of 5/3 the volume compressibility. Our values for the pnictides tend to be considerably larger than the PCM value as well as the wrong sign. The chalcogenide values are much nearer in magnitude and are of the right sign for the PCM. Contrary to the report of Guertin et al. we see no anomaly in the pressure dependence of the susceptibility of PrS. The fact that PrN which is reported to be non-metallic also shows the wrong sign for the PCM presents difficulties for various conduction electron explanations for this unexpected behavior of the pnictides

  11. Pressure and intracorporal acceleration measurements in pigs exposed to strong shock waves in a free field

    International Nuclear Information System (INIS)

    Vassout, P.; Franke, R.; Parmentier, G.; Evrard, G.; Dancer, A.

    1987-01-01

    A theoretical study on the propagation of a pressure wave in a diphasic medium, when compared to the onset mechanism of pulmonary lesions in subjects exposed to strong shock waves, shows an increase in the incident overpressure at the interface level. Using hydrophones, intracorporal pressure was measured in pigs. The authors recorded the costal wall acceleration on the side directly exposed to the shock wave and calculated the displacement of the costal wall after a shock wave passed by. These experiments were conducted for shock waves in a free field, at an overpressure peak level ranging from 26 kFPa to 380 kPa and for a first positive phase lasting 2 ms. Sensors placed in an intracorporal position detected no increase of the overpressure level for any value of the incident pressure. A comparison of the costal wall displacement, measured experimentally, relative to the theoretical displacement of the entire animal mass indicates that the largest relative displacement of the costal wall could be the origin of the pulmonary lesions found. 5 refs., 13 figs

  12. Use of Pressure-Redistributing Support Surfaces Among Elderly Hip Fracture Patients Across the Continuum of Care: Adherence to Pressure Ulcer Prevention Guidelines

    OpenAIRE

    Baumgarten, Mona; Margolis, David; Orwig, Denise; Hawkes, William; Rich, Shayna; Langenberg, Patricia; Shardell, Michelle; Palmer, Mary H.; McArdle, Patrick; Sterling, Robert; Jones, Patricia S.; Magaziner, Jay

    2009-01-01

    Purpose: To estimate the frequency of use of pressure-redistributing support surfaces (PRSS) among hip fracture patients and to determine whether higher pressure ulcer risk is associated with greater PRSS use. Design and Methods: Patients (n = 658) aged ≥65 years who had surgery for hip fracture were examined by research nurses at baseline and on alternating days for 21 days. Information on PRSS use and pressure ulcer risk factors was recorded at each assessment visit. Other information was o...

  13. Displacement of an electric arc by a stationary transverse magnetic field to different pressures of the ionized gas

    International Nuclear Information System (INIS)

    Ramos, J.

    1987-01-01

    The displacement of a wall-stabilized electric arc by a stationary transverse magnetic field is measured to different pressures of the ionized gas. The increase of the pressure makes the heat transfer function and the mass flow velocity in the arc column to raise, and it makes the arc displacement to decrease. (author)

  14. Variation of surface electric field during geomagnetic disturbed ...

    Indian Academy of Sciences (India)

    Atmospheric electric field; magnetic storm; magnetosphere; ionosphere; global electrical circuit. J. Earth Syst. Sci. 124, No. 8, December 2015, pp. ... cycle, climate and air pollution is insufficient for extensive applications. Hence, the ..... frequency radars monitoring plasma flow in the polar ionosphere. The network database ...

  15. Vector Magnetic Fields, Sub surface Stresses and Evolution of ...

    Indian Academy of Sciences (India)

    tribpo

    Arendt 1996). Bogdan (1984) found that flux tubes of the same sense of twist will merge if their relative velocities are slow enough to allow their magnetic fields to reconnect. Zweibel & Rhoads (1995) estimated an upper limit to the critical velocity and concluded that colliding twisted flux tubes may coalesce at the base of the ...

  16. Effective stresses and shear failure pressure from in situ Biot's coefficient, Hejre Field, North Sea

    DEFF Research Database (Denmark)

    Regel, Jeppe Bendix; Orozova-Bekkevold, Ivanka; Andreassen, Katrine Alling

    2017-01-01

    We propose a combination of Biot's equations for effective stress and the expression for shear failure in a rock to obtain an expression for minimum pore pressure in a stable vertical well bore. We show that a Biot's coefficient calculated from logging data in the Hejre Field, North Sea, is signi......We propose a combination of Biot's equations for effective stress and the expression for shear failure in a rock to obtain an expression for minimum pore pressure in a stable vertical well bore. We show that a Biot's coefficient calculated from logging data in the Hejre Field, North Sea......, is significantly different from 1. The log-derived Biot's coefficient is above 0.8 in the Shetland Chalk Group and in the Tyne Group, and 0.6-0.8 in the Heno Sandstone Formation. We show that the effective vertical and horizontal stresses obtained using the log-derived Biot's coefficient result in a drilling...... window for a vertical well larger than if approximating Biot's coefficient by 1. The estimation of the Biot's coefficient is straightforward in formations with a stiff frame, whereas in formations such as shales, caution has to be taken. We discuss the consequence of assumptions made on the mineral...

  17. Development of a pressure based room acoustic model using impedance descriptions of surfaces

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2013-01-01

    and acoustic radiosity will account for the diffuse reflections. This paper presents the motivation for the new model in the form of results in literature, which show the importance of retaining the angle dependence and phase information in reflections along with simple examples of angle dependent reflection......If a simulation tool is to be used for the optimization of absorbent ceilings, it is important that the simulation tool includes a good description of the surface. This study therefore aims at developing a model which can describe surfaces by their impedance values and not just by their statistical...... absorption coefficient, thus retaining the phase and the angle dependence. The approach of the proposed model will be to calculate the pressure impulse response using a combination of the image source method and acoustic radiosity. The image source method will account for the specular reflections...

  18. Interfacial effects of surface-active agents under zinc pressure leach conditions

    Science.gov (United States)

    Owusu, George; Dreisinger, David B.; Peters, Ernest

    1995-02-01

    Liquid sulfur-zinc sulfate solution interfacial tensions and liquid sulfur-zinc sulfate solution-zinc sulfide (marmatite) contact angles were measured in the absence and presence of surface-active agents. Interfacial tensions measured varied between 54 ± 1 mN/m in the surfactant-free system and 20 ± 1 mN/m in the presence of a surfactant. The liquid sulfur-zinc sulfide mineral-zinc sulfate solution contact angle varies between 80 ± 5 deg, in the absence of any surfactant, and 148 ± 5 deg, depending on the surfactant used. The surface-active agents were used as dispersants for sulfur in bench-scale zinc pressure-leaching experiments. The observed extent of zinc extraction depends on the surfactant and varies from 40 to 96 pct.

  19. Near field evidence of backward surface plasmon polaritons on negative index material boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas, Mauro, E-mail: cuevas@df.uba.ar [Facultad de Ingeniería y Tecnología Informática, Universidad de Belgrano, Villanueva 1324, C1426BMJ, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Grunhut, Vivian [Facultad de Ingeniería, Universidad Austral (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Depine, Ricardo A. [Grupo de Electromagnetismo Aplicado, Departamento de Física, FCEN, Universidad de Buenos Aires and IFIBA, Ciudad Universitaria, Pabellón I, C1428EHA, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina)

    2016-12-09

    Highlights: • Electromagnetic scattering from a localized defect on a NIM surface is presented. • The electromagnetic response strongly depends on the SPPs excited. • Near field distribution reveals the forward or backward character of SPPs excited. - Abstract: We present a detailed analysis about the electromagnetic response of a metamaterial surface with a localized defect. The excitation of electromagnetic surface waves leads to a near-field distribution showing a periodic dependence along the metamaterial surface. We find that this periodic pattern provides a direct demonstration of the forward or backward surface wave propagation.

  20. Surface impedance of superconductors in wide frequency ranges for wake field calculations

    International Nuclear Information System (INIS)

    Davidovskii, V.G.

    2006-01-01

    The problem of the surface impedance of superconductors in wide frequency ranges for calculations of wake fields, generated by bunches of charged particles moving axially inside a metallic vacuum chambers, is solved. The case of specular electron reflection at the superconductor surface is considered. The expression for the surface impedance of superconductors suitable for numerical computation is derived [ru

  1. Electric fields control the orientation of peptides irreversibly immobilized on radical-functionalized surfaces.

    Science.gov (United States)

    Martin, Lewis J; Akhavan, Behnam; Bilek, Marcela M M

    2018-01-24

    Surface functionalization of an implantable device with bioactive molecules can overcome adverse biological responses by promoting specific local tissue integration. Bioactive peptides have advantages over larger protein molecules due to their robustness and sterilizability. Their relatively small size presents opportunities to control the peptide orientation on approach to a surface to achieve favourable presentation of bioactive motifs. Here we demonstrate control of the orientation of surface-bound peptides by tuning electric fields at the surface during immobilization. Guided by computational simulations, a peptide with a linear conformation in solution is designed. Electric fields are used to control the peptide approach towards a radical-functionalized surface. Spontaneous, irreversible immobilization is achieved when the peptide makes contact with the surface. Our findings show that control of both peptide orientation and surface concentration is achieved simply by varying the solution pH or by applying an electric field as delivered by a small battery.

  2. Modifying the photodetachment near a metal surface by a weak electric field

    OpenAIRE

    Yang, B. C.; Du, M. L.

    2009-01-01

    We show the photodetachment cross sections of H near a metal surface can be modified using a weak static electric field. The modification is possible because the oscillatory part of the cross section near a metal surface is directly connected with the transit-time and the action of the detached-electron closed-orbit which can be changed systematically by varying the static electric field strength. Photodetachment cross sections for various photon energies and electric field values are calcula...

  3. Simulation of surface displacement and strain field of the 2011 Japan Mw9.0 earthquake

    Directory of Open Access Journals (Sweden)

    Chen Shujun

    2011-11-01

    Full Text Available Based on dislocation theory of Okada, we adopted a finite-element fault model inverted by Gavin Hayes from seismic data for the 2011 Japan Mw9.0 earthquake, and obtained the corresponding surface displacement and strain fields. The calculated displacement field is consistent with the observed GPS results in the trend of changes. Also the surface displacement and strain fields both show large variations in space.

  4. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    Science.gov (United States)

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  5. 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.

  6. Computational model of the interaction of a helium atmospheric-pressure jet with a dielectric surface

    Science.gov (United States)

    Hasan, M. I.; Bradley, J. W.

    2015-11-01

    Using a time-dependent two-dimensional axisymmetric fluid model the interaction of a plasma jet with a dielectric surface has been studied. The model is solved for two consecutive periods of a positive unipolar pulsed waveform. The study concentrates on determining the fluxes of the main oxygen ion species, \\text{O}2+ , \\text{O}2- and the total accumulated charge on the surface. Approaching the dielectric surface, the streamer head is seen to divert its direction of propagation, spreading out radially approximately 0.2 mm above the dielectric surface. For \\text{O}2+ generated near the streamer head, this leads to a maximum in their flux to the surface which moves radially outwards with the streamer propagation, driven by the applied electric field in pulse on-time. In the off-time, the flux of \\text{O}2+ drops by at least two orders of magnitude. As a result, the total number of \\text{O}2+ ions arriving at the surface over one entire pulse period (fluence) has an annular shape limited by the effective contact area of the streamer on the surface. In contrast \\text{O}2- ions generated in the pulse on-time do not reach the surface due to the direction of the applied electric field. In the off-time, \\text{O}2- ions generated at the edges of the deformed streamer are pushed by the accumulated surface charge outwards. As a result, the \\text{O}2- fluence has an annular structure with its maximum being outside the area of the dielectric surface covered by the plasma channel. Solving for the second pulse period shows small changes in the predicted fluences, with largest difference seen with \\text{O}2- . We see that increasing the flow rate (by a factor of three) shifts the position of the maximum fluence of \\text{O}2+ outwards, and decreasing the \\text{O}2- fluence in the second pulse period.

  7. Effect of electrode configuration on the uniformity of atmospheric pressure surface dielectric barrier air micro-discharge

    Science.gov (United States)

    Xia, Yang; Bi, Zhenhua; Qi, Zhihua; Ji, Longfei; Zhao, Yao; Chang, Xuewei; Wang, Wenchun; Liu, Dongping

    2018-02-01

    The electrode configuration of atmospheric pressure air discharge is one of the key elements that have significant effects on the discharge properties. In this study, double-sided printed circuit boards with square-shaped lattice structure are used to generate surface dielectric barrier air micro-discharge (SDBAMD) at atmospheric pressure. The effects of the lattice width on the discharge properties are reported. The uniformity of the SDBAMD is evaluated by adopting the digital image processing method. Our measurements show that the power and ignition voltage of the SDBAMD significantly depended on the configuration of the grounded electrode. The digital image processing results show that the uniformity of the SDBAMD is severely affected by the lattice width, and the most uniform discharge is achieved at the lattice width of 2.0 mm. The numerical model based on COMSOL demonstrated that increasing the lattice width can lead to an increase in the electric field in the vicinity of the grounded electrode and a decrease in the lattice center. Furthermore, our analysis suggests that the different electrode configurations can change the interaction between the space charges during the discharge, which ultimately affects the uniformity of the SDBAMD.

  8. Role of west Asian surface pressure in summer monsoon onset over central India

    Science.gov (United States)

    Chakraborty, Arindam; Agrawal, Shubhi

    2017-07-01

    Using rain-gauge measurements and reanalysis data sets for 1948-2015, we propose a mechanism that controls the interannual variation of summer monsoon onset over central India. In May, about a month before the onset, the low level jet over the Arabian Sea is about 40% stronger and about 2.5 degrees northward during years of early onset as compared to years of late onset. A stronger and northward shifted low level jet carries about 50% more moisture in early onset years, which increases low level moist static energy over central India in the pre-monsoon season. The increase in low level moist static energy decreases the stability of the atmosphere and makes it conducive for convection. The strength and position of the low level jet are determined by surface pressure gradient between western Asia and the west-equatorial Indian Ocean. Thus, an anomalous surface pressure low over western Asia in the pre-monsoon season increases this gradient and strengthens the jet. Moreover, a stronger low level jet increases the meridional shear of zonal wind and supports the formation of an onset vortex in a stronger baroclinic atmosphere. These developments are favourable for an early onset of the monsoon over the central Indian region. Our study postulates a new physical mechanism for the interannual variation of onset over central India, the core of the Indian monsoon region and relevant to Indian agriculture, and could be tested for real-time prediction.

  9. Variability of the Surface Meteorological Fields over Eurasia for the Recent 30 Years

    International Nuclear Information System (INIS)

    Basharin, D.V.

    2009-10-01

    On the basis of the Japanese reanalysis (JRA25) dataset (1979-2008), linear trends, interannual to decadal variability of the sea level pressure (SLP), surface air temperature (SAT) and precipitation fields over the Eurasian region have been studied. For the recent 30 years there are only significant positive linear trends of SAT in the northwestern part of the Eurasia/eastern Asia in winter and central Europe in summer. Areas with significant negative trends of SAT are absent. For precipitation field there are no significant tendencies except for the significantly positive area over England both in winter and in summer time. In winter, there are two areas with the opposite SLP tendencies: insignificant negative (to the north of 45-50N) and significant positive (to the south of 45-50N) one. These trends could be accompanied by the corresponding tendencies bee-hive reproduction and honey production in different regions of Ukraine. Space-time patterns of the first, second and third EOF of the fields under study are mainly determined by the NAO and in the less extent by the SO (only in spring-summer). It was found that the leading modes become more contributive over the Eurasia for the last 30 years comparing with NCEP data for the previous period (1950-2001). It could imply that an internal signal of the ocean-atmosphere system, which determines space-time patterns over Eurasia, has arisen. Intercomparison of the space-time EOF patterns between JRA25 and NCEP (1950-2001) re-analyses show that in autumn, winter and spring the first 3-4 corresponding time coefficients stay at the same order (coefficient correlations between them are significant), while in summer such correspondence in order of modes is changed. (author)

  10. System for supporting conception in the field of surface treatments

    International Nuclear Information System (INIS)

    Evrard, J.M.; Gras, M.

    1989-01-01

    The application of the techniques issued from artificial intelligence for assisting the development of a computer technical memory on a representative subject, which is the surface treatments and coating in tribology, is illustrated. The development of the system is composed of several steps: data acquisition and formatting representation, data validation and software. Particular attention is given to the dialogue between the user and the system. The study shows that the development of the following points are indispensable: the possibility of following the user's reasoning and coming back to previous steps or exploring several parallel ways [fr

  11. Simulation of changes in temperature and pressure fields during high speed projectiles forming by explosion

    Directory of Open Access Journals (Sweden)

    Marković Miloš D.

    2016-01-01

    Full Text Available The Research in this paper considered the temperatures fields as the consequently influenced effects appeared by plastic deformation, in the explosively forming process aimed to design Explosively Formed Projectiles (henceforth EFP. As the special payloads of the missiles, used projectiles are packaged as the metal liners, joined with explosive charges, to design explosive propulsion effect. Their final form and velocity during shaping depend on distributed temperatures in explosively driven plastic deformation process. Developed simulation model consider forming process without metal cover of explosive charge, in aim to discover liner’s dynamical correlations of effective plastic strains and temperatures in the unconstrained detonation environment made by payload construction. The temperature fields of the liner’s copper material are considered in time, as the consequence of strain/stress displacements driven by explosion environmental thermodynamically fields of pressures and temperatures. Achieved final velocities and mass loses as the expected EFP performances are estimated regarding their dynamical shaping and thermal gradients behavior vs. effective plastic strains. Performances and parameters are presented vs. process time, numerically simulated by the Autodyne software package. [Projekat Ministarstva nauke Republike Srbije, br. III-47029

  12. An effective field study of the magnetic properties and critical behaviour at the surface Ising film

    International Nuclear Information System (INIS)

    Bengrine, M.; Benyoussef, A.; Ez-Zahraouy, H.; Mhirech, F.

    1998-09-01

    The influence of corrugation and disorder at the surface on the critical behaviour of a ferromagnetic spin-1/2 Ising film is investigated using mean-field theory and finite cluster approximation. It is found that the critical surface exponent β 1 follows closely the one of a perfect surface, in the two cases: corrugated surface and random equiprobable coupling surface. However, in the case of flat surface with random interactions the surface critical exponent β 1 depends on the concentration p of the strong interaction for p>p c =0,5, while for p≤p c , such critical exponent is independent on the value of p and is equal to the one of the perfect surface. Moreover, in the case of corrugated surface, the effective exponent for a layer z, β eff J(z,n), is calculated as a function of the number of steps at the surface. (author)

  13. Modeling and Analysis of The Pressure Die Casting Using Response Surface Methodology

    International Nuclear Information System (INIS)

    Kittur, Jayant K.; Herwadkar, T. V.; Parappagoudar, M. B.

    2010-01-01

    Pressure die casting is successfully used in the manufacture of Aluminum alloys components for automobile and many other industries. Die casting is a process involving many process parameters having complex relationship with the quality of the cast product. Though various process parameters have influence on the quality of die cast component, major influence is seen by the die casting machine parameters and their proper settings. In the present work, non-linear regression models have been developed for making predictions and analyzing the effect of die casting machine parameters on the performance characteristics of die casting process. Design of Experiments (DOE) with Response Surface Methodology (RSM) has been used to analyze the effect of effect of input parameters and their interaction on the response and further used to develop nonlinear input-output relationships. Die casting machine parameters, namely, fast shot velocity, slow shot to fast shot change over point, intensification pressure and holding time have been considered as the input variables. The quality characteristics of the cast product were determined by porosity, hardness and surface rough roughness (output/responses). Design of experiments has been used to plan the experiments and analyze the impact of variables on the quality of casting. On the other-hand Response Surface Methodology (Central Composite Design) is utilized to develop non-linear input-output relationships (regression models). The developed regression models have been tested for their statistical adequacy through ANOVA test. The practical usefulness of these models has been tested with some test cases. These models can be used to make the predictions about different quality characteristics, for the known set of die casting machine parameters, without conducting the experiments.

  14. Design, fabrication, and implementation of a wireless, passive implantable pressure sensor based on magnetic higher-order harmonic fields.

    Science.gov (United States)

    Tan, Ee Lim; DeRouin, Andrew J; Pereles, Brandon D; Ong, Keat Ghee

    2011-10-17

    A passive and wireless sensor was developed for monitoring pressure in vivo. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is an airtight chamber sealed with an elastic pressure membrane. A strip of magnetically-soft material is attached to the bottom of the chamber and a permanent magnet strip is embedded inside the membrane. Under the excitation of an externally applied AC magnetic field, the magnetically-soft strip produces a higher-order magnetic signature that can be remotely detected with an external receiving coil. As ambient pressure varies, the pressure membrane deflects, altering the separation distance between the magnetically-soft strip and the permanent magnet. This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting. The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi. In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment.

  15. Design, Fabrication, and Implementation of a Wireless, Passive Implantable Pressure Sensor Based on Magnetic Higher-Order Harmonic Fields

    Directory of Open Access Journals (Sweden)

    Keat Ghee Ong

    2011-10-01

    Full Text Available A passive and wireless sensor was developed for monitoring pressure in vivo. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is an airtight chamber sealed with an elastic pressure membrane. A strip of magnetically-soft material is attached to the bottom of the chamber and a permanent magnet strip is embedded inside the membrane. Under the excitation of an externally applied AC magnetic field, the magnetically-soft strip produces a higher-order magnetic signature that can be remotely detected with an external receiving coil. As ambient pressure varies, the pressure membrane deflects, altering the separation distance between the magnetically-soft strip and the permanent magnet. This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting. The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi. In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment.

  16. Influence of the vortex shedding on the time evolution of instantaneous pressure fields and forces in rotating airfoils

    Science.gov (United States)

    Villegas, Arturo; Diez, Francisco J.

    2013-11-01

    Time-resolved measurements of instantaneous pressure fields and aerodynamic loads are obtained for rotating airfoils. These allowed evaluating temporal variations in the flow field and were able to capture the evolution of vortex shedding in the wake of the rotating blade. The results show the influence of vortex shedding in the instantaneous loads. These measurements involve obtaining first the velocity field from TR-PIV. This is used to calculate the pressure field from the Poisson pressure equation, and later the forces from the integral momentum equation. The robustness of the measurements is analyzed by calculating the PIV uncertainty, and the independence of the calculated forces. Experimental mean aerodynamic forces are compared to theoretical predictions from the Blade Element Momentum theory (BEM) showing good agreement. The instantaneous pressure varied with time only in the wake due to vortex shedding. This is the first time the evolution of the instantaneous pressure field has been resolved for a rotating airfoil. The contribution to the instantaneous forces from each term in the integral momentum equation is evaluated. The analysis shows that the larger contributions to the normal force coefficient are from the unsteady and the pressure terms while the larger contribution to the tangential force coefficient is from the convective term. The method can be used to measure unsteady forces in rotating airfoils, providing useful information not just for computational studies, but also for aerodynamics, material and structural optimization and safety purposes.

  17. Fermi surface studies of the pressure induced organic superconductor (ET){sub 3}Cl{sub 2}.2H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Lubczynski, W. [Physics Dept., Clarendon Lab., Univ. of Oxford (United Kingdom); Caulfield, J. [Physics Dept., Clarendon Lab., Univ. of Oxford (United Kingdom); Singleton, J. [Physics Dept., Clarendon Lab., Univ. of Oxford (United Kingdom); Hayes, W. [Physics Dept., Clarendon Lab., Univ. of Oxford (United Kingdom); Kurmoo, M. [Royal Institution, London (United Kingdom); Day, P. [Royal Institution, London (United Kingdom)

    1995-03-15

    The effects of temperature, pressure and magnetic field on the electrical transport of single crystal of (ET){sub 3}Cl{sub 2}.2H{sub 2}O are reported. Increasing pressure gradually reduces the ordering temperature of a charge density wave ground state from {approx}160 K at 1 bar to 6 K at 10.2 kbar. A superconducting state with T{sub c}>4 K is stabilised between 10.2 kbar and 13.5 kbar. Above 12.5 kbar, the observation of Shubnikov-de Haas oscillations allows the pressure dependences of the area of a closed Fermi surface pocket and the associated carrier effective mass to be deduced. (orig.)

  18. Prevention of pressure ulcers in the intensive care unit: a randomized trial of 2 viscoelastic foam support surfaces.

    Science.gov (United States)

    Ozyurek, Pakize; Yavuz, Meryem

    2015-01-01

    The aim of this study is to compare whether differences exist between 2 viscoelastic foam support surfaces in the development of new pressure ulcers. There is evidence to support the use of viscoelastic foam over standard hospital foam to reduce pressure. A comparative effectiveness study was done to compare 2 viscoelastic foam support surfaces. A randomized controlled trial was carried out. The study was performed in 2 intensive care units between October 1, 2008, and January 4, 2010. Patients (n = 105) admitted to intensive care unit were randomly assigned to viscoelastic foam 1 (n = 53) or viscoelastic foam 2 support surface (n = 52). In total, 42.8% of all patients developed a new pressure ulcer of stage 1 or worse. By stages, pressure ulcer incidence was 28.6%, 13.3%, and 1.0% for stages 1, 2, and 3, respectively. There was no significant difference in pressure ulcer incidence between the viscoelastic foam 1 and 2 groups (X2 = 0.07, df = 1, P > .05). No difference was found between 2 different viscoelastic foam surfaces in the prevention of pressure ulcers in patients treated in intensive care. Pressure ulcer incidence in critically ill patients remains high. Nurses must compare current products for effectiveness and develop innovative systems, processes, or devices to deliver best practices.

  19. Changes in Land Surface Water Dynamics since the 1990s and Relation to Population Pressure

    Science.gov (United States)

    Prigent, C.; Papa, F.; Aires, F.; Jimenez, C.; Rossow, W. B.; Matthews, E.

    2012-01-01

    We developed a remote sensing approach based on multi-satellite observations, which provides an unprecedented estimate of monthly distribution and area of land-surface open water over the whole globe. Results for 1993 to 2007 exhibit a large seasonal and inter-annual variability of the inundation extent with an overall decline in global average maximum inundated area of 6% during the fifteen-year period, primarily in tropical and subtropical South America and South Asia. The largest declines of open water are found where large increases in population have occurred over the last two decades, suggesting a global scale effect of human activities on continental surface freshwater: denser population can impact local hydrology by reducing freshwater extent, by draining marshes and wetlands, and by increasing water withdrawals. Citation: Prigent, C., F. Papa, F. Aires, C. Jimenez, W. B. Rossow, and E. Matthews (2012), Changes in land surface water dynamics since the 1990s and relation to population pressure, in section 4, insisting on the potential applications of the wetland dataset.

  20. Forward projection of transient sound pressure fields radiated by impacted plates using numerical Laplace transform.

    Science.gov (United States)

    Blais, Jean-François; Ross, Annie

    2009-05-01

    Forward propagation of the transient sound pressure radiated by an impacted plate is presented. It is shown that direct and inverse time domain discrete Fourier transforms, involved in Fourier transform based near-field acoustical holography (NAH), lead to aliasing errors in the reconstructed time signals. Adding trailing zeros to the initial time signals is an inefficient way to reduce time aliasing errors. Hence, the numerical Laplace transform is introduced and a Fourier transform based transient NAH (TNAH) approach is formulated. An error measure is introduced to compare both NAH and TNAH with respect to the propagation distance and the location of the observation point in the projection plane. The percentage of error with TNAH is reduced by more than a factor of 10 without adding trailing zeros to the initial signals. Simulation results are validated experimentally using a free Plexiglas plate impacted at its center.

  1. High-pressure low-field 1H NMR relaxometry in nanoporous materials.

    Science.gov (United States)

    Horch, Carsten; Schlayer, Stefan; Stallmach, Frank

    2014-03-01

    A low-field NMR sensor with NdFeB permanent magnets (B0=118 mT) and a pressure cell made of PEEK (4 cm outer diameter) were designed for (1)H relaxation time studies of adsorbed molecules at pressures of up to 300 bar. The system was used to investigate methane uptake of microporous metal-organic frameworks and nanoporous activated carbon. T2 relaxation time distribution of pure methane and of methane under co-adsorption of carbon dioxide show that the host-guest interaction lead to a relaxation time contrasts, which may be used to distinguish between the gas phase and the different adsorbed phases of methane. Adsorption isotherms, exchange of methane between adsorbent particles and the surrounding gas phase, successive displacement of methane from adsorption sites by co-adsorption of carbon dioxide and CO2/CH4 adsorption separation factors were determined from the observed NMR relaxation time distributions. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. STRONG SOLAR WIND DYNAMIC PRESSURE PULSES: INTERPLANETARY SOURCES AND THEIR IMPACTS ON GEOSYNCHRONOUS MAGNETIC FIELDS

    International Nuclear Information System (INIS)

    Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Xu, Xiaojun

    2015-01-01

    In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector

  3. Absolute Height of Sea Surface by Trajectory of GPS Antennae Over Submerged Pressure Gauges

    Science.gov (United States)

    Bouin, M.; Calmant, S.; Cheng, K.; Ballu, V.; Shum, C. K.; Testut, L.

    2003-12-01

    Water height data provided by seafloor tide gauges is a combination of sea-level variations and ground motion. Both of these signals are of scientific interest, but they must be separated in order to be useful. Estimating ground motion is specially important in very tectonically active areas such as the Pacific Ocean rim. One promising method to separate the two contributions is to use satellite altimetry data which gives absolute water height, but these data must be calibrated using ground truth measurements. Once different components of the signal are separated, bottom pressure gauges can be used to detect vertical movements of the seafloor such as co-seismic or slow inter-seismic motions. The Vanuatu archipelago is part of the Pacific ring of fire, where plates are rapidly converging. In the area, movements are very rapid and the seismic activity is intense, which gives a good opportunity to study deformation and seismic cycle. To get an integrate picture of vertical deformation over one plate and between the two plates, one needs to be able to monitor vertical movements on both underwater and emerged areas. We conducted an experiment in the Vanuatu archipelago, South-West Pacific, to compare measurements from bottom pressure gauges located beneath altimetry satellite tracks with sea surface altitude measurements from GPS. Two bottom pressure gauges are immerged since Nov. 1999 on Sabine bank (15.90° S, 166.14° E) and Wusi Bank (15.34° S, 166.55° E), West of Santo island, Vanuatu. In order to perform absolute calibrations of JASON and ENVISAT altimeters that overfly the Wusi and Sabine banks, respectively, we performed GPS measurements of instantaneous sea surface altitude. The GPS antennae were fixed on top of the 30m long R/V Alis. An inertial unit also recorded the high frequency vessel motions. The height of the antennae over the sea surface was measured using a laser distancemeter in calibration sessions during particularly calm sea states. We present

  4. Surface acoustic wave electric field effect on acoustic streaming: Numerical analysis

    Science.gov (United States)

    Darinskii, A. N.; Weihnacht, M.; Schmidt, H.

    2018-01-01

    The paper numerically studies the contribution of the electric field accompanying the surface acoustic wave to the actuation of the acoustic streaming in microchannels. The finite element method is used. The results obtained as applied to the surface waves on 128° and 64°-rotated Y cuts of LiNbO3 demonstrate that the force created by the electric field is capable of accelerating appreciably the acoustic streaming. In particular, examples are given for the situations where the electric field increases the streaming velocity by a factor of about 2-3 and significantly changes the flow pattern as compared to predictions of computations ignoring the electric field.

  5. Instrumental system for the quick relief of surface temperatures in fumaroles fields and steam heated soils

    Science.gov (United States)

    Diliberto, Iole; Cappuzzo, Santo; Inguaggiato, Salvatore; Cosenza, Paolo

    2014-05-01

    .g. in mofettes and diffuse degassing areas). The occurrence of thermal anomalies at the surface often reveals that a process of steam condensation is occurring below the ground and that CO2 fluxes are being released on the surface. A thermal map of steam heated grounds therefore highlights boundaries of underground steam advection and also the more suitable sites for geochemical monitoring. Pirogips has been assembled for the quick acquisition of surface parameters related to the exhaling activity of volcanic systems. It has been formerly tested in a controlled environment, after in the well known fumaroles areas of Vulcano island, and then in the volcanic system El Machin (Colombia) for the field survey preliminary to the installation of new monitoring stations. The preliminary test and the first field experiences confirmed that pirogips acquires the surface temperatures quickly and with good detail. The combination of sensors supplies the advantage of in situ methods (i.e. accuracy of the direct measurement by thermocouple) and those of ground-based remote sensing techniques (i.e. quickness of measurement process), at the same time reducing the main disadvantages of each method. A home-made data-logger combines the acquired parameters and returns a data-string allowing an easy visualization of acquired data on geo-referenced maps. The string of data returns the position of acquisition (lat, long, WGS84), surface temperature (either derived by the pyrometer and by thermocouple), ambient temperature, barometric pressure and air moisture. -References -Diliberto I.S., Gurrieri S., Valenza M. (2002) Relationships between diffuse CO2 emissions and volcanic activity on the island of Vulcano (Aeolian Islands, Italy) during the period 1984-1994 Bulletin of Volcanology vol 64: 219-228. -Diliberto I.S., (2013) Time series analysis of high temperature fumaroles monitored on the island of Vulcano (Aeolian Archipelago, italy). Journal of Volcanology and Geothermal Research

  6. Hydrothermal surface alteration in the Copahue Geothermal Field (Argentina)

    Energy Technology Data Exchange (ETDEWEB)

    Mas, Graciela R.; Mas, Luis C.; Bengochea, Leandro

    1996-01-24

    In the area of the Copahue Geothermal Field, there are five active geothermal manifestations, which mainly consist of fumaroles, hot springs and mud pots. Four of these manifestations are located in Argentina: Las Máquinas, Termas de Copahue, Las Maquinitas and El Anfiteatro, and the fifth on the Chilean side: Chancho Co. All of them present a strong acid sulfate country rock alteration, characterized by the assemblage alunite + kaolinite + quartz + cristobalite + pyrite + sulfur + jarosite, as the result of the base leaching by fluids concentrated in H2SO4 by atmospheric oxidation at the water table in a steam heated environment of H2S released by deeper boiling fluids. Another alteration zone in this area, called COP-2, is a fossil geothermal manifestation which shows characteristics of neutral to alkaline alteration represented mainly by the siliceous sinter superimposed over the acid alteration. The mineralogy and zoning of these alteration zones, and their relation with the hidrothermal solutions and the major structures of the area are analized.

  7. Effects of the Mach number on the evolution of vortex-surface fields in compressible Taylor-Green flows

    Science.gov (United States)

    Peng, Naifu; Yang, Yue

    2018-01-01

    We investigate the evolution of vortex-surface fields (VSFs) in compressible Taylor-Green flows at Mach numbers (Ma) ranging from 0.5 to 2.0 using direct numerical simulation. The formulation of VSFs in incompressible flows is extended to compressible flows, and a mass-based renormalization of VSFs is used to facilitate characterizing the evolution of a particular vortex surface. The effects of the Mach number on the VSF evolution are different in three stages. In the early stage, the jumps of the compressive velocity component near shocklets generate sinks to contract surrounding vortex surfaces, which shrink vortex volume and distort vortex surfaces. The subsequent reconnection of vortex surfaces, quantified by the minimal distance between approaching vortex surfaces and the exchange of vorticity fluxes, occurs earlier and has a higher reconnection degree for larger Ma owing to the dilatational dissipation and shocklet-induced reconnection of vortex lines. In the late stage, the positive dissipation rate and negative pressure work accelerate the loss of kinetic energy and suppress vortex twisting with increasing Ma.

  8. 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

  9. Measured ground-surface movements, Cerro Prieto geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Massey, B.L.

    1981-01-01

    The Cerro Prieto geothermal area in the Mexicali Valley, 30 kilometers southeast of Mexicali, Baja California, incurred slight deformation because of the extraction of hot water and steam, and probably, active tectonism. During 1977 to 1978, the US Geological Survey established and measured two networks of horizontal control in an effort to define both types of movement. These networks consisted of: (1) a regional trilateration net brought into the mountain ranges west of the geothermal area from stations on an existing US Geological Survey crustal-strain network north of the international border; and (2) a local net tied to stations in the regional net and encompassing the present and planned geothermal production area. Electronic distance measuring instruments were used to measure the distances between stations in both networks in 1978, 1979 and 1981. Lines in the regional net averaged 25 km. in length and the standard deviation of an individual measurement is estimated to be approx. 0.3 part per million of line length. The local network was measured using different instrumentation and techniques. The average line length was about 5 km. and the standard deviation of an individual measurement approached 3 parts per million per line length. Ground-surface movements in the regional net, as measured by both the 1979 and 1981 resurveys, were small and did not exceed the noise level. The 1979 resurvey of the local net showed an apparent movement of 2 to 3 centimeters inward toward the center of the production area. This apparent movement was restricted to the general limits of the production area. The 1981 resurvey of the local net did not show increased movement attributable to fluid extraction.

  10. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    DEFF Research Database (Denmark)

    Fumagalli, F; Kylian, O; Amato, Letizia

    2012-01-01

    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can...... be achieved using pure H2O or Ar/H2O mixtures at low temperatures with removal rates comparable to oxygen-based mixtures. Particle fluxes (Ar+ ions, O and H atomic radicals and OH molecular radicals) from water vapour discharge are measured by optical emission spectroscopy and Langmuir probe under several...... operating conditions. Analysis of particle fluxes and removal rates measurements illustrates the role of ion bombardment associated with O radicals, governing the removal rates of organic matter. Auxiliary role of hydroxyl radicals is discussed on the basis of experimental data. The advantages of a water...

  11. Low pressure plasma discharges for the sterilization and decontamination of surfaces

    International Nuclear Information System (INIS)

    Rossi, F; Rauscher, H; Hasiwa, M; Gilliland, D; Kylian, O

    2009-01-01

    The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O 2 mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their de-activation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.

  12. Low pressure plasma discharges for the sterilization and decontamination of surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, F; Rauscher, H; Hasiwa, M; Gilliland, D [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Via E. Fermi 2749, 21027 Ispra (Vatican City State, Holy See) (Italy); Kylian, O [Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, Prague 8, 180 00 (Czech Republic)], E-mail: francois.rossi@jrc.ec.europa.eu

    2009-11-15

    The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O{sub 2} mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their de-activation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.

  13. Influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure

    Science.gov (United States)

    Pechereau, François; Bonaventura, Zdeněk; Bourdon, Anne

    2016-08-01

    This paper presents simulations of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer parallel to the cathode plane. Experimentally, a discharge reignition in the air gap below the dielectrics has been observed. With a 2D fluid model, it is shown that due to the fast rise of the high voltage applied and the sharp point used, a first positive spherical discharge forms around the point. Then this discharge propagates axially and impacts the dielectrics. As the first discharge starts spreading on the upper dielectric surface, in the second air gap with a low preionization density of {{10}4}~\\text{c}{{\\text{m}}-3} , the 2D fluid model predicts a rapid reignition of a positive discharge. As in experiments, the discharge reignition is much slower, a discussion on physical processes to be considered in the model to increase the reignition delay is presented. The limit case with no initial seed charges in the second air gap has been studied. First, we have calculated the time to release an electron from the cathode surface by thermionic and field emission processes for a work function φ \\in ≤ft[3,4\\right] eV and an amplification factor β \\in ≤ft[100,220\\right] . Then a 3D Monte Carlo model has been used to follow the dynamics of formation of an avalanche starting from a single electron emitted at the cathode. Due to the high electric field in the second air gap, we have shown that in a few nanoseconds, a Gaussian cloud of seed charges is formed at a small distance from the cathode plane. This Gaussian cloud has been used as the initial condition of the 2D fluid model in the second air gap. In this case, the propagation of a double headed discharge in the second air gap has been observed and the reignition delay is in rather good agreement with experiments.

  14. Experimental and numerical investigations of stable crack growth of axial surface flaws in a pressure vessel

    International Nuclear Information System (INIS)

    Brocks, W.; Krafka, H.; Mueller, W.; Wobst, K.

    1988-01-01

    In connection with the problem of the transferability of parameters obtained experimentally with the help of fracture-mechanical test specimens and used for the initiation and the stable propagation of cracks in cases of pulsating stress and of the elasto-plastic behaviour of construction components, a pressure vessel with an inside diameter of 1500 mm, a cylindrical length of 3000 mm and a wall thickness of 40 mm was hydraulically loaded with the help of internal pressure in the first stage, to attain an average crack growth of 1 mm at Δ a ≅, the loading taking place at about 21deg C. This stress-free annealed vessel exhibited an axial semielliptical vibration-induced surface crack about 181 mm long and 20 mm deep, as a test defect, in a welded circular blank made of the steel 20MnMoNi 55. The fractographic analysis of the first stable crack revealed that its growth rate of Δa was highest in the area of transition from the weak to the strong bend of the crack front (55deg m /σ v (average principal stress: σ m , Mises' reference stress: σ v v). A comparison of the experimental with the numerical results from the first stable crack shows that the local stable crack growth Δa cannot be calculated solely with reference to J, because Δa appears to depend essentially on the quotient σ m /σ v . (orig./MM) [de

  15. Diagnostics of surface wave driven low pressure plasmas based on indium monoiodide-argon system

    International Nuclear Information System (INIS)

    Ögün, C M; Kaiser, C; Kling, R; Heering, W

    2015-01-01

    Indium monoiodide is proposed as a suitable alternative to hazardous mercury, i.e. the emitting component inside the compact fluorescent lamps (CFL), with comparable luminous efficacy. Indium monoiodide-argon low pressure lamps are electrodelessly driven with surface waves, which are launched and coupled into the lamp by the ‘surfatron’, a microwave coupler optimized for an efficient operation at a frequency of 2.45 GHz. A non intrusive diagnostic method based on spatially resolved optical emission spectroscopy is employed to characterize the plasma parameters. The line emission coefficients of the plasma are derived by means of Abel’s inversion from the measured spectral radiance data. The characteristic plasma parameters, e.g. electron temperature and density are determined by comparing the experimentally obtained line emission coefficients with simulated ones from a collisional-radiative model. Additionally, a method to determine the absolute plasma efficiency via irradiance measurements without any goniometric setup is presented. In this way, the relationship between the plasma efficiency and the plasma parameters can be investigated systematically for different operating configurations, e.g. electrical input power, buffer gas pressure and cold spot temperature. The performance of indium monoiodide-argon plasma is compared with that of conventional CFLs. (paper)

  16. Field emission and high voltage cleaning of particulate contaminants on extended metallic surfaces

    International Nuclear Information System (INIS)

    Tan, J.; Bonin, B.; Safa, H.

    1996-01-01

    The vacuum insulation properties of extended metallic surfaces depends strongly on their cleanliness. The usual technique to reduce electronic field emission from such surfaces consists in exposing them to very high electric fields during limited periods of time. This kind of processing also reduces the occurrence of vacuum breakdown. The processing of the surface is generally believed to be due to a thermomechanical destruction of the emitting sites, initiated by the emission itself. Comparison of the electric forces vs adherence forces which act on dust particles lying on the surface shows that the processing could also be due simply to the mechanical removal of the dust particles, with a subsequent reduction of field emission from the contaminated surface. (author)

  17. Modification of the Steel Surface Treated by a Volume Discharge Plasma in Nitrogen at Atmospheric Pressure

    Science.gov (United States)

    Erofeev, M. V.; Shulepov, M. A.; Ivanov, Yu. F.; Oskomov, K. V.; Tarasenko, V. F.

    2016-03-01

    Effect of volume discharge plasma initiated by an avalanche electron beam on the composition, structure, and properties of the surface steel layer is investigated. Voltage pulses with incident wave amplitude up to 30 kV, full width at half maximum of about 4 ns, and wave front of about 2.5 ns were applied to the gap with an inhomogeneous electric field. Changes indicating the hardening effect of the volume discharge initiated by an avalanche electron beam are revealed in St3-grade steel specimens treated by the discharge of this type.

  18. Construction of a carbonate reservoir model using pressure transient data : field case study

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, S. [Petro-Iran, (Iran, Islamic Republic of); Ghanizadeh, M. [Tehran Energy, (Iran, Islamic Republic of); Haghighi, M. [Tehran Univ., (Iran, Islamic Republic of)

    2004-07-01

    Pressure transient data was integrated with other reservoir information to create a geological model of a carbonate reservoir in the Salaman offshore field in Iran. The model was created using seismic and well log data as well as the interpretation of 99 well tests performed in this field. Several features such as sealing faults, aquifer, fracturing and layering systems were observed. Two faults were identified in the northern part of the reservoir. The distance between the major fault and well number 27 was less than predicted from seismic data. An active aquifer and minor fault were also identified near well number 6. A fracture system was identified around well number 22. Most well tests showed communication between different layers of the reservoirs, suggesting interconnected layers in terms of geology. All calculated permeabilities from the well tests were found to be significantly higher than those from core analysis, suggesting that discrete fractures exist throughout the reservoir. The northern region of the reservoir has the highest permeability values and the lowest values are observed in the central part of the reservoir. 18 refs., 6 figs.

  19. Aqueous electrolyte surfaces in strong electric fields: molecular insight into nanoscale jets and bridges

    Science.gov (United States)

    Jirsák, Jan; Moučka, Filip; Škvor, Jiří; Nezbeda, Ivo

    2015-04-01

    Exposing aqueous surfaces to a strong electric field gives rise to interesting phenomena, such as formation of a floating water bridge or an eruption of a jet in electrospinning. In an effort to account for the phenomena at the molecular level, we performed molecular dynamics simulations using several protocols on both pure water and aqueous solutions of sodium chloride subjected to an electrostatic field. All simulations consistently point to the same mechanisms which govern the rearrangement of the originally planar surface. The results show that the phenomena are primarily governed by an orientational reordering of the water molecules driven by the applied field. It is demonstrated that, for pure water, a sufficiently strong field yields a columnar structure parallel to the field with an anisotropic arrangement of the water molecules with their dipole moments aligned along the applied field not only in the surface layer but over the entire cross section of the column. Nonetheless, the number of hydrogen bonds per molecule does not seem to be affected by the field regardless of its strength and molecule's orientation. In the electrolyte solutions, the ionic charge is able to overcome the effect of the external field tending to arrange the water molecules radially in the first coordination shell of an ion. The ion-water interaction interferes thus with the water-electric field interaction, and the competition between these two forces (i.e., strength of the field versus concentration) provides the key mechanism determining the stability of the observed structures.

  20. Extended KN algebras and extended conformal field theories over higher genus Riemann surfaces

    International Nuclear Information System (INIS)

    Ceresole, A.; Huang Chaoshang

    1990-01-01

    A global operator formalism for extended conformal field theories over higher genus Riemann surfaces is introduced and extended KN algebra are obtained by means of the KN bases. The BBSS construction of the spin-3 operator is carried out for Kac-Moody algebra A 2 over a Riemann surface of arbitrary genus. (orig.)

  1. High-pressure coolant effect on the surface integrity of machining titanium alloy Ti-6Al-4V: a review

    Science.gov (United States)

    Liu, Wentao; Liu, Zhanqiang

    2018-03-01

    Machinability improvement of titanium alloy Ti-6Al-4V is a challenging work in academic and industrial applications owing to its low thermal conductivity, low elasticity modulus and high chemical affinity at high temperatures. Surface integrity of titanium alloys Ti-6Al-4V is prominent in estimating the quality of machined components. The surface topography (surface defects and surface roughness) and the residual stress induced by machining Ti-6Al-4V occupy pivotal roles for the sustainability of Ti-6Al-4V components. High-pressure coolant (HPC) is a potential choice in meeting the requirements for the manufacture and application of Ti-6Al-4V. This paper reviews the progress towards the improvements of Ti-6Al4V surface integrity under HPC. Various researches of surface integrity characteristics have been reported. In particularly, surface roughness, surface defects, residual stress as well as work hardening are investigated in order to evaluate the machined surface qualities. Several coolant parameters (including coolant type, coolant pressure and the injection position) deserve investigating to provide the guidance for a satisfied machined surface. The review also provides a clear roadmap for applications of HPC in machining Ti-6Al4V. Experimental studies and analysis are reviewed to better understand the surface integrity under HPC machining process. A distinct discussion has been presented regarding the limitations and highlights of the prospective for machining Ti-6Al4V under HPC.

  2. Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

    Science.gov (United States)

    Li, Zhanguo; Li, Ying; Cao, Peng; Zhao, Hongjie

    2013-07-01

    An atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator using air flow as the feedstock gas was applied to decontaminate the chemical agent surrogates on the surface of aluminum, stainless steel or iron plate painted with alkyd or PVC. The experimental results of material decontamination show that the residual chemical agent on the material is lower than the permissible value of the National Military Standard of China. In order to test the corrosion effect of the plasma jet on different material surfaces in the decontamination process, corrosion tests for the materials of polymethyl methacrylate, neoprene, polyvinyl chloride (PVC), polyethylene (PE), phenolic resin, iron plate painted with alkyd, stainless steel, aluminum, etc. were carried out, and relevant parameters were examined, including etiolation index, chromatism, loss of gloss, corrosion form, etc. The results show that the plasma jet is slightly corrosive for part of the materials, but their performances are not affected. A portable calculator, computer display, mainboard, circuit board of radiogram, and a hygrometer could work normally after being treated by the plasma jet.

  3. Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

    International Nuclear Information System (INIS)

    Li Zhanguo; Li Ying; Cao Peng; Zhao Hongjie

    2013-01-01

    An atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator using air flow as the feedstock gas was applied to decontaminate the chemical agent surrogates on the surface of aluminum, stainless steel or iron plate painted with alkyd or PVC. The experimental results of material decontamination show that the residual chemical agent on the material is lower than the permissible value of the National Military Standard of China. In order to test the corrosion effect of the plasma jet on different material surfaces in the decontamination process, corrosion tests for the materials of polymethyl methacrylate, neoprene, polyvinyl chloride (PVC), polyethylene (PE), phenolic resin, iron plate painted with alkyd, stainless steel, aluminum, etc. were carried out, and relevant parameters were examined, including etiolation index, chromatism, loss of gloss, corrosion form, etc. The results show that the plasma jet is slightly corrosive for part of the materials, but their performances are not affected. A portable calculator, computer display, mainboard, circuit board of radiogram, and a hygrometer could work normally after being treated by the plasma jet

  4. Cell treatment and surface functionalization using a miniature atmospheric pressure glow discharge plasma torch

    International Nuclear Information System (INIS)

    Yonson, S; Coulombe, S; Leveille, V; Leask, R L

    2006-01-01

    A miniature atmospheric pressure glow discharge plasma torch was used to detach cells from a polystyrene Petri dish. The detached cells were successfully transplanted to a second dish and a proliferation assay showed the transplanted cells continued to grow. Propidium iodide diffused into the cells, suggesting that the cell membrane had been permeabilized, yet the cells remained viable 24 h after treatment. In separate experiments, hydrophobic, bacteriological grade polystyrene Petri dishes were functionalized. The plasma treatment reduced the contact angle from 93 0 to 35 0 , and promoted cell adhesion. Two different torch nozzles, 500 μm and 150 μm in internal diameter, were used in the surface functionalization experiments. The width of the tracks functionalized by the torch, as visualized by cell adhesion, was approximately twice the inside diameter of the nozzle. These results indicate that the miniature plasma torch could be used in biological micropatterning, as it does not use chemicals like the present photolithographic techniques. Due to its small size and manouvrability, the torch also has the ability to pattern complex 3D surfaces

  5. Quantitative measurements of ground state atomic oxygen in atmospheric pressure surface micro-discharge array

    Science.gov (United States)

    Li, D.; Kong, M. G.; Britun, N.; Snyders, R.; Leys, C.; Nikiforov, A.

    2017-06-01

    The generation of atomic oxygen in an array of surface micro-discharge, working in atmospheric pressure He/O2 or Ar/O2 mixtures, is investigated. The absolute atomic oxygen density and its temporal and spatial dynamics are studied by means of two-photon absorption laser-induced fluorescence. A high density of atomic oxygen is detected in the He/O2 mixture with up to 10% O2 content in the feed gas, whereas the atomic oxygen concentration in the Ar/O2 mixture stays below the detection limit of 1013 cm-3. The measured O density near the electrode under the optimal conditions in He/1.75% O2 gas is 4.26  ×  1015 cm-3. The existence of the ground state O (2p 4 3 P) species has been proven in the discharge at a distance up to 12 mm away from the electrodes. Dissociative reactions of the singlet O2 with O3 and deep vacuum ultraviolet radiation, including the radiation of excimer \\text{He}2\\ast , are proposed to be responsible for O (2p 4 3 P) production in the far afterglow. A capability of the surface micro-discharge array delivering atomic oxygen to long distances over a large area is considered very interesting for various biomedical applications.

  6. Elimination of diazinon insecticide from cucumber surface by atmospheric pressure air-dielectric barrier discharge plasma.

    Science.gov (United States)

    Dorraki, Naghme; Mahdavi, Vahideh; Ghomi, Hamid; Ghasempour, Alireza

    2016-12-06

    The food industry is in a constant search for new technologies to improve the commercial sterilization process of agricultural commodities. Plasma treatment may offer a novel and efficient method for pesticide removal from agricultural product surfaces. To study the proposed technique of plasma food treatment, the degradation behavior of diazinon insecticide by air-dielectric barrier discharge (DBD) plasma was investigated. The authors studied the effect of different plasma powers and treatment times on pesticide concentration in liquid form and coated on the surface of cucumbers, where the diazinon residue was analyzed with mass spectroscopy gas chromatography. Our results suggest that atmospheric pressure air-DBD plasma is potentially effective for the degradation of diazinon insecticide, and mainly depends on related operating parameters, including plasma treatment time, discharge power, and pesticide concentrations. Based on the interaction between reactive oxygen species and electrons in the plasma with the diazinon molecule, two degradation pathway of diazinon during plasma treatment are proposed. It was also found that produced organophosphate pesticides are harmless and less hazardous compounds than diazinon.

  7. Waves on the surface of a magnetic fluid layer in a traveling magnetic field

    International Nuclear Information System (INIS)

    Zimmermann, K.; Zeidis, I.; Naletova, V.A.; Turkov, V.A.

    2004-01-01

    The plane flow of a layer of incompressible viscous magnetic fluid with constant magnetic permeability under the action of a traveling magnetic field is analyzed. The strength of the magnetic field producing a sinusoidal traveling small-amplitude wave on the surface of a magnetic fluid is found. This flow can be used in designing mobile robots

  8. Effects of electric field on a copper–dioxolene complex adsorbed on a gold surface

    Energy Technology Data Exchange (ETDEWEB)

    Kostyrko, T., E-mail: tkos@amu.edu.pl; Ślusarski, T.

    2016-06-15

    Highlights: • Cu–dioxolene complex at Au(1 1 1) surface in electric field was studied with a DFT+U method. • Two valence tautomers of the adsorbed Cu–dioxolene complex were described. • Coulomb correlations on Cu make driving force for valence tautomeric transitions. • Electric field of strength of 0.5 V/Å can almost fully ionize the adsorbed complex. - Abstract: A model of a copper–dioxolene complex linked to Au(1 1 1) surface with butanethiol linker is investigated using first-principles methods. It is shown that the complex adsorbed at the surface may appear in various locally stable structural forms differing in electron charge and spin density distribution, the symmetric high spin (HS) one and the twisted low spin (LS) structure. The electric field directed perpendicular to the surface controls the amount of the charge transfer between the complex and the substrate, starting from the zero-field value of Q = +0.18 |e| up to the value of Q = +0.94 |e| for the field strength of E = 0.5 V/Å. The field modifies also the mutual stability of the two structural forms, reducing the energy gap between the more energetically stable LS twisted form and the symmetrical HS one, from a value of Δ ∼ 0.29 eV in absence of the field to Δ ∼ 0.11 eV for the field strength of E = 0.35 V/Å.

  9. High-field 3He-F interaction at the surface of fluorocarbon spheres

    DEFF Research Database (Denmark)

    Schuhl, A.; Chapellier, M.; Rasmussen, Finn Berg

    1984-01-01

    High-field experiments on the relaxation betweenF in small Teflon spheres andHe on the surface are reported. WithHe as a monolayer, coupling times are found to be less than 5 sec, in magnetic fields up to 3 T and temperatures down to 50 mK, where electronic centers are completely polarized...

  10. Comparison of air-fluidized therapy with other support surfaces used to treat pressure ulcers in nursing home residents.

    Science.gov (United States)

    Ochs, Rachel F; Horn, Susan D; van Rijswijk, Lia; Pietsch, Catherine; Smout, Randall J

    2005-02-01

    To provide empirical evidence comparing pressure ulcer healing rates between different support surfaces, data were analyzed from eligible residents with pressure ulcers (N = 664) enrolled in the National Pressure Ulcer Long-Term Care Study, a retrospective pressure ulcer prevention and treatment study. Support surfaces were categorized as: Group 1 (static overlays and replacement mattresses), Group 2 (low-air-loss beds, alternating pressure, and powered/non-powered overlays/mattresses), and Group 3 (air-fluidized beds). Calculation of healing rates, using the largest ulcer from each resident, found mean healing rates greatest for air-fluidized therapy (Group 3) (mean = 5.2 cm(2)/week) versus Group 1 (mean =1.5 cm(2)/week) and Group 2 (mean = 1.8 cm(2)/week) surfaces (P = 0.007). Healing rates also were assessed using 7- to 10-day "episodes"; each ulcer generated separate episode(s) that included all ulcers when residents had multiple ulcers. Mean healing rates were significantly greater for Stage III/IV ulcers on Group 3 surfaces (mean = 3.1 cm(2)/week) versus Group 1 (mean = 0.6 cm(2)/week) and Group 2 (mean = 0.7 cm(2)/week) surfaces (Group 2 versus Group 3: P = 0.0211). This finding persisted for ulcers with comparable initial baseline areas (20 cm(2) to 75 cm(2)) on Group 2 and Group 3 surfaces; healing improved on Group 3 surfaces (+2.3 cm(2)/week) versus Group 2 surfaces (-2.1 cm(2)/week, P = 0.0399). Residents on Group 3 (6 out of 82; 7.3%) and Group 1 (47 out of 461; 10.2%) surfaces had fewer hospitalizations and emergency room visits than those on Group 2 surfaces (23 out of 121; 19.0%, P = 0.01) despite significantly greater illness in residents on Group 2 and 3 versus Group 1 surfaces (P is less than 0.0001). Despite limitations inherent in retrospective studies, ulcers on Group 3 surfaces versus Groups 1 and Group 2 surfaces had statistically significant faster healing rates (particularly for Stage III/IV ulcers) with significantly fewer

  11. Evolution effects of the copper surface morphology on the nucleation density and growth of graphene domains at different growth pressures

    Energy Technology Data Exchange (ETDEWEB)

    Hedayat, Seyed Mahdi [Transport Phenomena & Nanotechnology Lab., School of Chemical Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of); Karimi-Sabet, Javad, E-mail: j_karimi@alum.sharif.edu [NFCRS, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Shariaty-Niassar, Mojtaba, E-mail: mshariat@ut.ac.ir [Transport Phenomena & Nanotechnology Lab., School of Chemical Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of)

    2017-03-31

    Highlights: • Manipulation of the Cu surface morphology in a wide range by electropolishing treatment. • Comparison of the nucleation density of graphene at low pressure and atmospheric pressure CVD processes. • Controlling the evolution of the Cu surface morphology inside a novel confined space. • Growth of large-size graphene domains. - Abstract: In this work, we study the influence of the surface morphology of the catalytic copper substrate on the nucleation density and the growth rate of graphene domains at low and atmospheric pressure chemical vapor deposition (LPCVD and APCVD) processes. In order to obtain a wide range of initial surface morphology, precisely controlled electropolishing methods were developed to manipulate the roughntreess value of the as-received Cu substrate (RMS = 30 nm) to ultra-rough (RMS = 130 nm) and ultra-smooth (RMS = 2 nm) surfaces. The nucleation and growth of graphene domains show obviously different trends at LPCVD and APCVD conditions. In contrast to APCVD condition, the nucleation density of graphene domains is almost equal in substrates with different initial roughness values at LPCVD condition. We show that this is due to the evolution of the surface morphology of the Cu substrate during the graphene growth steps. By stopping the surface sublimation of copper substrate in a confined space saturated with Cu atoms, the evolution of the Cu surface was impeded. This results in the reduction of the nucleation density of graphene domains up to 24 times in the pre-smoothed Cu substrates at LPCVD condition.

  12. Properties and cleanability of new and traditional surface materials in cattle barns - a field study

    Directory of Open Access Journals (Sweden)

    R. KUISMA

    2008-12-01

    Full Text Available In this study surface properties and cleanability of new and traditional surface materials in cattle barns were examined in a field test. The concrete and plastic-coated samples were placed on a walking path on the floor and on a feeding table in a cattle barn. The surfaces were characterized using colorimetric and gloss measurements and determination of topography. In most cases, the colour of the surfaces placed on the floor darkened during the one year study period, whereas the colour changes of the samples placed on the feeding table did not show a similar trend. However, in both locations the plastic-coated surfaces were generally the easiest to clean, and the highest colour changes indicating soil residues were detected on the uncoated and silane-impregnated concrete surfaces. The difference between the locations was also seen in the gloss values, which increased in the samples placed on the floor during the one-year test period but varied considerably between the different materials on the surfaces placed on the feeding table. This field study confirmed the observation from earlier laboratory studies that plastic coatings improved the cleanability of concrete cattle barn surfaces. Silane impregnation was not functionally competitive with the plastic coatings. In general, the cleanability results were in accordance with the results of previous laboratory experiments but the field study provided practical information about the behaviour of the surface materials examined.;

  13. Design and fabrication of a system simultaneously available under high pressure, high magnetic field and low temperature for neutron scattering

    International Nuclear Information System (INIS)

    Kawano, Shinji; Fukui, Susumu; Onodera, Akifumi; Amita, Fujitsugu; Matsumoto, Kiyoshi; Ohtomo, Akitoshi; Moriai, Atsushi; Katano, Susumu.

    1997-01-01

    We have designed and developed a system for neutron scattering experiments simultaneously available under high pressure, high magnetic field and low temperatures. The system consists of a clamp-type high pressure cell whose targeting pressure is about 2.5GPa, a superconducting magnet achievable to 5T vertically, and a variable-temperature insertion in which the cell is placed and liquid helium is transfered through a needle valve from the liquid helium reservoir. The results of a performance test is reported. (author)

  14. Numerical Calculation of the Correlation Moments of the Sound Field Scattered by a Rough Surface

    Science.gov (United States)

    Baranov, V. F.; Gulin, É. P.

    2000-05-01

    Numerically calculated two-dimensional correlation moments of the surface-scattered sound field are presented in the form of correlation surfaces and analyzed. The models of three-dimensional anisotropic and two-dimensional quasi-harmonic surface waves are considered. Data are presented on the angular dependence of the space-time correlation domains of the scattered sound field for receivers spaced across the propagation path in both horizontal and vertical directions, as well as on the shapes of the time-frequency and space-frequency correlation domains.

  15. Study of luminous phenomena observed on contaminated metallic surfaces submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Bonin, B.; Luong, M.; Safa, H.; Tan, J.

    1995-01-01

    The RF field emission from a sample subjected to high RF fields in a copper cavity has been investigated. The study is focused on the luminous emissions occurring on the RF surface simultaneously with the electron emission. The optical apparatus attached to the cavity permits to observe the evolution of the emitters and the direct effects of the surface conditioning. Also, the parameters of the emitted radiation (intensity, glowing duration, spectral distribution) may provide additional informations on the field emission phenomena. Some results concerning samples intentionally contaminated with particles (metallic or dielectric) are presented. (K.A.)

  16. Monte Carlo characterization of skin doses in 6 MV transverse field MRI-linac systems: effect of field size, surface orientation, magnetic field strength, and exit bolus.

    Science.gov (United States)

    Oborn, B M; Metcalfe, P E; Butson, M J; Rosenfeld, A B

    2010-10-01

    The main focus of this work is to continue investigations into the Monte Carlo predicted skin doses seen in MRI-guided radiotherapy. In particular, the authors aim to characterize the 70 microm skin doses over a larger range of magnetic field strength and x-ray field size than in the current literature. The effect of surface orientation on both the entry and exit sides is also studied. Finally, the use of exit bolus is also investigated for minimizing the negative effects of the electron return effect (ERE) on the exit skin dose. High resolution GEANT4 Monte Carlo simulations of a water phantom exposed to a 6 MV x-ray beam (Varian 2100C) have been performed. Transverse magnetic fields of strengths between 0 and 3 T have been applied to a 30 x 30 x 20 cm3 phantom. This phantom is also altered to have variable entry and exit surfaces with respect to the beam central axis and they range from -75 degrees to +75 degrees. The exit bolus simulated is a 1 cm thick (water equivalent) slab located on the beam exit side. On the entry side, significant skin doses at the beam central axis are reported for large positive surface angles and strong magnetic fields. However, over the entry surface angle range of -30 degrees to -60 degrees, the entry skin dose is comparable to or less than the zero magnetic field skin dose, regardless of magnetic field strength and field size. On the exit side, moderate to high central axis skin dose increases are expected except at large positive surface angles. For exit bolus of 1 cm thickness, the central axis exit skin dose becomes an almost consistent value regardless of magnetic field strength or exit surface angle. This is due to the almost complete absorption of the ERE electrons by the bolus. There is an ideal entry angle range of -30 degrees to -60 degrees where entry skin dose is comparable to or less than the zero magnetic field skin dose. Other than this, the entry skin dose increases are significant, especially at higher magnetic

  17. Neural Network Prediction of Failure of Damaged Composite Pressure Vessels from Strain Field Data Acquired by a Computer Vision Method

    Science.gov (United States)

    Russell, Samuel S.; Lansing, Matthew D.

    1997-01-01

    This effort used a new and novel method of acquiring strains called Sub-pixel Digital Video Image Correlation (SDVIC) on impact damaged Kevlar/epoxy filament wound pressure vessels during a proof test. To predict the burst pressure, the hoop strain field distribution around the impact location from three vessels was used to train a neural network. The network was then tested on additional pressure vessels. Several variations on the network were tried. The best results were obtained using a single hidden layer. SDVIC is a fill-field non-contact computer vision technique which provides in-plane deformation and strain data over a load differential. This method was used to determine hoop and axial displacements, hoop and axial linear strains, the in-plane shear strains and rotations in the regions surrounding impact sites in filament wound pressure vessels (FWPV) during proof loading by internal pressurization. The relationship between these deformation measurement values and the remaining life of the pressure vessels, however, requires a complex theoretical model or numerical simulation. Both of these techniques are time consuming and complicated. Previous results using neural network methods had been successful in predicting the burst pressure for graphite/epoxy pressure vessels based upon acoustic emission (AE) measurements in similar tests. The neural network associates the character of the AE amplitude distribution, which depends upon the extent of impact damage, with the burst pressure. Similarly, higher amounts of impact damage are theorized to cause a higher amount of strain concentration in the damage effected zone at a given pressure and result in lower burst pressures. This relationship suggests that a neural network might be able to find an empirical relationship between the SDVIC strain field data and the burst pressure, analogous to the AE method, with greater speed and simplicity than theoretical or finite element modeling. The process of testing SDVIC

  18. High temperature and high pressure oxidation behavior of Zr-2.5Nb pressure tube material – Effect of β phase composition and surface machining

    Energy Technology Data Exchange (ETDEWEB)

    Nouduru, S.K., E-mail: nouduru@barc.gov.in [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Kumar, M. Kiran; Kain, Vivekanand [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Khanna, A.S. [Dept. of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Saibaba, N. [Nuclear Fuel Complex, ECILPost, Hyderabad 500062 (India); Dey, G.K. [Materials Science Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2016-03-15

    Pressure tube material, Zr-2.5Nb, of pressurized heavy water reactors was given selective heat-treatments. The objective was to generate microstructures with different compositions of the second phase β namely, Νb depleted β{sub Zr} phase and Nb rich β{sub Nb} phase. The material with β{sub Zr} was then subjected to surface machining. The presence of phases after different heat-treatments was confirmed by X-ray diffraction and the resultant microstructures were characterized by transmission electron microscopy and electron back scattered diffraction. The Nb content in the β phase after heat-treatments and residual stresses before and after surface machining were measured using X-ray diffraction. Oxidation was carried out in steam at 400 °C and 10 MPa up to 30 days and the oxides were characterized by Raman spectroscopy. It is shown that the presence of Nb rich β{sub Nb} in the microstructure and faster diffusion of Nb into β phase brought about by surface machining resulted in an enhanced oxidation resistance. - Highlights: • Effect of heat treatments in formation of Nb rich/depleted phases established. • Microstructure with β{sub Nb} and Nb depleted α shown to have high oxidation resistance. • Surface machining resulted in grain refinement, strain and tensile residual stress. • Surface machining improved oxidation resistance and its extent increased with time. • Machined specimen showed higher fraction of tetragonal zirconia.

  19. High temperature and high pressure oxidation behavior of Zr-2.5Nb pressure tube material – Effect of β phase composition and surface machining

    International Nuclear Information System (INIS)

    Nouduru, S.K.; Kumar, M. Kiran; Kain, Vivekanand; Khanna, A.S.; Saibaba, N.; Dey, G.K.

    2016-01-01

    Pressure tube material, Zr-2.5Nb, of pressurized heavy water reactors was given selective heat-treatments. The objective was to generate microstructures with different compositions of the second phase β namely, Νb depleted β Zr phase and Nb rich β Nb phase. The material with β Zr was then subjected to surface machining. The presence of phases after different heat-treatments was confirmed by X-ray diffraction and the resultant microstructures were characterized by transmission electron microscopy and electron back scattered diffraction. The Nb content in the β phase after heat-treatments and residual stresses before and after surface machining were measured using X-ray diffraction. Oxidation was carried out in steam at 400 °C and 10 MPa up to 30 days and the oxides were characterized by Raman spectroscopy. It is shown that the presence of Nb rich β Nb in the microstructure and faster diffusion of Nb into β phase brought about by surface machining resulted in an enhanced oxidation resistance. - Highlights: • Effect of heat treatments in formation of Nb rich/depleted phases established. • Microstructure with β Nb and Nb depleted α shown to have high oxidation resistance. • Surface machining resulted in grain refinement, strain and tensile residual stress. • Surface machining improved oxidation resistance and its extent increased with time. • Machined specimen showed higher fraction of tetragonal zirconia.

  20. Shallow donor impurities in different shaped double quantum wells under the hydrostatic pressure and applied electric field

    International Nuclear Information System (INIS)

    Kasapoglu, E.; Sari, H.; Sokmen, I.

    2005-01-01

    The combined electric field and hydrostatic pressure effects on the binding energy of the donor impurity in double triangle quantum well (DTQW), double graded (DGQW) and double square (DSQW) GaAs-(Ga,Al)As quantum wells are calculated by using a variational technique within the effective-mass approximation. The results have been obtained in the presence of an electric field applied along the growth direction as a function of hydrostatic pressure, the impurity position, barrier width and the geometric shape of the double quantum wells

  1. Fast electric field waveforms and near-surface electric field images of lightning discharges detected on Mt. Aragats in Armenia

    International Nuclear Information System (INIS)

    Chilingarian, A.; Khanikyants, Y.; Kozliner, L.; Soghomonyan, S.

    2016-01-01

    We present the observational data on fast electric waveforms that are detected at 3200 m altitudes above sea level on Mt. Aragats in Armenia during thunderstorms. We analyse the relations of these forms with count rates of particle flux (during Thunderstorm Ground Enhancements -TGEs); to the slow disturbance of the near-surface electrostatic field; and to the lightning location data from the World Wide Lightning Location Network (WWLLN). An observed negative lightning that decreases a negative charge overhead often abruptly terminates TGEs. By analysing the recorded fast electric field waveforms and comparing them with similar classified waveforms reported previously, we could identify the type and polarity of the observed lightnings. (author)

  2. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems.

    Science.gov (United States)

    Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

    2015-11-25

    For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p'-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis.

  3. Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

    Science.gov (United States)

    de Vries, N.; Palomares, J. M.; Iordanova, E. I.; van Veldhuizen, E. M.; van der Mullen, J. J. A. M.

    2008-10-01

    The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, ne, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, Te, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the ne values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 ± 0.5) × 1019 m-3, whereas the ne value (2 ± 0.5) × 1019 m-3 obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high (~1020 m-3). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the Te values obtained with TS are equal to 13 400 ± 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

  4. Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vries, N de; Iordanova, E I; Van Veldhuizen, E M; Mullen, J J A M van der [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Palomares, J M [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain)], E-mail: j.j.a.m.v.d.Mullen@tue.nl

    2008-10-21

    The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, n{sub e}, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, T{sub e}, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the n{sub e} values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 {+-} 0.5) x 10{sup 19} m{sup -3}, whereas the n{sub e} value (2 {+-} 0.5) x 10{sup 19} m{sup -3} obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high ({approx}10{sup 20} m{sup -3}). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the T{sub e} values obtained with TS are equal to 13 400 {+-} 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

  5. Correlations of Surface Deformation and 3D Flow Field in a Compliant Wall Turbulent Channel Flow.

    Science.gov (United States)

    Wang, Jin; Zhang, Cao; Katz, Joseph

    2015-11-01

    This study focuses on the correlations between surface deformation and flow features, including velocity, vorticity and pressure, in a turbulent channel flow over a flat, compliant Polydimethylsiloxane (PDMS) wall. The channel centerline velocity is 2.5 m/s, and the friction Reynolds number is 2.3x103. Analysis is based on simultaneous measurements of the time resolved 3D velocity and surface deformation using tomographic PIV and Mach-Zehnder Interferometry. The volumetric pressure distribution is calculated plane by plane by spatially integrating the material acceleration using virtual boundary, omni-directional method. Conditional sampling based on local high/low pressure and deformation events reveals the primary flow structures causing the deformation. High pressure peaks appear at the interface between sweep and ejection, whereas the negative deformations peaks (dent) appear upstream, under the sweeps. The persistent phase lag between flow and deformations are presumably caused by internal damping within the PDMS. Some of the low pressure peaks and strong ejections are located under the head of hairpin vortices, and accordingly, are associated with positive deformation (bump). Others bumps and dents are correlated with some spanwise offset large inclined quasi-streamwise vortices that are not necessarily associated with hairpins. Sponsored by ONR.

  6. Advanced Production Surface Preparation Technology Development for Ultra-High Pressure Diesel Injection

    Energy Technology Data Exchange (ETDEWEB)

    Grant, Marion B.

    2012-04-30

    In 2007, An Ultra High Injection Pressure (UHIP) fueling method has been demonstrated by Caterpillar Fuel Systems - Product Development, demonstrating ability to deliver U.S. Environment Protection Agency (EPA) Tier 4 Final diesel engine emission performance with greatly reduced emissions handling components on the engine, such as without NOx reduction after-treatment and with only a through-flow 50% effective diesel particulate trap (DPT). They have shown this capability using multiple multi-cylinder engine tests of an Ultra High Pressure Common Rail (UHPCR) fuel system with higher than traditional levels of CEGR and an advanced injector nozzle design. The system delivered better atomization of the fuel, for more complete burn, to greatly reduce diesel particulates, while CEGR or high efficiency NOx reduction after-treatment handles the NOx. With the reduced back pressure of a traditional DPT, and with the more complete fuel burn, the system reduced levels of fuel consumption by 2.4% for similar delivery of torque and horsepower over the best Tier 4 Interim levels of fuel consumption in the diesel power industry. The challenge is to manufacture the components in high-volume production that can withstand the required higher pressure injection. Production processes must be developed to increase the toughness of the injector steel to withstand the UHIP pulsations and generate near perfect form and finish in the sub-millimeter size geometries within the injector. This project resulted in two developments in 2011. The first development was a process and a machine specification by which a high target of compressive residual stress (CRS) can be consistently imparted to key surfaces of the fuel system to increase the toughness of the steel, and a demonstration of the feasibility of further refinement of the process for use in volume production. The second development was the demonstration of the feasibility of a process for imparting near perfect, durable geometry to

  7. Status of researches in the field of safety of pressurized water reactors

    International Nuclear Information System (INIS)

    Couturier, Jean; Schwarz, Michel

    2017-01-01

    This collective publication proposes a synthesis of the status of researches performed in the field of safety of pressurized water reactors. They may discuss past, current and projected research works, involved actors, or lessons learned from these works. The authors propose a presentation of some research tools privileged by the IRSN for these researches: the CABRI and PHEBUS reactors, the GALAXIE experimental platform, and some other installations. Then they address researches related to loss-of-coolant accidents (two-phase thermohydraulics, fuel rod behaviour), to reactivity accidents, to accidents related to dewatering of irradiated fuel storage pools, to fires, to extreme aggressions of natural origin (earthquake, extreme flooding), to core fusion accidents (core heating and fusion within the vessel, vessel failure and apron erosion by corium, containment enclosure dynamic loading, release of radioactive products), to the behaviour of nuclear plant important metallic or civil works components and notably to their ageing, to organisational and human factors or more generally to social and human sciences (design of control rooms, safety organisation and management in EDF nuclear plants), and to other issues and research perspectives

  8. Ionization Capabilities of Hydronium Ions and High Electric Fields Produced by Atmospheric Pressure Corona Discharge.

    Science.gov (United States)

    Sato, Natsuhiko; Sekimoto, Kanako; Takayama, Mitsuo

    2016-01-01

    Atmospheric pressure corona discharge (APCD) was applied to the ionization of volatile organic compounds. The mass spectra of analytes having aromatic, phenolic, anilinic, basic and aliphatic in nature were obtained by using vapor supply and liquid smear supply methods. The vapor supply method mainly gave protonated analytes [A+H] + caused by proton transfer from hydronium ion H 3 O + , except for benzene, toluene and n -hexane that have lower proton affinity. The use of the liquid smear supply method resulted in the formation of molecular ion A ·+ and/or dehydride analyte [A-H] + , according to the nature of analytes used. The formation of A ·+ without fragment ions could be explained by the electron tunneling via high electric fields 10 8  V/m at the tip of the corona needle. The dehydride analytes [A-H] + observed in the mass spectra of n -hexane, di- and tributylamines may be explained by the hydride abstraction from the alkyl chains by the hydronium ion. The hydronium ion can play the two-roles for analytes, i.e. , the proton donor to form [A+H] + and the hydride acceptor to form [A-H] + .

  9. Pulsed Electromagnetic Field (PEMF) Mitigates High Intracranial Pressure (ICP) Induced Microvascular Shunting (MVS) in Rats.

    Science.gov (United States)

    Bragin, Denis E; Bragina, Olga A; Hagberg, Sean; Nemoto, Edwin M

    2018-01-01

    High-frequency pulsed electromagnetic field (PEMF) stimulation is an emerging noninvasive therapy that we have shown increases cerebral blood flow (CBF) and tissue oxygenation in the healthy rat brain. In this work, we tested the effect of PEMF on the brain at high intracranial pressure (ICP). We previously showed that high ICP in rats caused a transition from capillary (CAP) to non-nutritive microvascular shunt (MVS) flow, tissue hypoxia and increased blood brain barrier (BBB) permeability. Using in vivo two-photon laser scanning microscopy (2PLSM) over the rat parietal cortex, and studied the effects of PEMF on microvascular blood flow velocity, tissue oxygenation (NADH autofluorescence), BBB permeability and neuronal necrosis during 4 h of elevated ICP to 30 mmHg. PEMF significantly dilated arterioles, increased capillary blood flow velocity and reduced MVS/capillary ratio compared to sham-treated animals. These effects led to a significant decrease in tissue hypoxia, BBB degradation and neuronal necrosis. PEMF attenuates high ICP-induced pathological microcirculatory changes, tissue hypoxia, BBB degradation and neuronal necrosis.

  10. Effect of chemical pressure on the crystal electric field states of erbium pyrochlore magnets

    Science.gov (United States)

    Gaudet, J.; Hallas, A. M.; Kolesnikov, A. I.; Gaulin, B. D.

    2018-01-01

    We have carried out a systematic study of the crystal electric field excitations in the family of cubic pyrochlores Er2B2O7 with B =Ge , Ti, Pt, and Sn, using neutron spectroscopy. All members of this family are magnetic insulators based on 4 f11Er3 + and nonmagnetic B4 +. At sufficiently low temperatures, long-range antiferromagnetic order is observed in each of these Er2B2O7 pyrochlores. The different ionic sizes associated with different nonmagnetic B4 + cations correspond to positive or negative chemical pressure, depending on the relative contraction or expansion of the crystal lattice, which gives rise to different local environments at the Er3 + site. Our results show that the g -tensor components are X Y -like for all four members of the Er2B2O7 series. However, the X Y anisotropy is much stronger for Er2Pt2O7 and Er2Sn2O7(g⊥/gz>25 ) than for Er2Ge2O7 and Er2Ti2O7(g⊥/gz<4 ) . The variation in the nature of the X Y anisotropy in these systems correlates strongly with their ground states as Er2Ge2O7 and Er2Ti2O7 order into Γ5 magnetic structures, whereas Er2Pt2O7 and Er2Sn2O7 order in the Γ7 Palmer-Chalker structure.

  11. Assessment of Field Experience Related to Pressurized Water Reactor Primary System Leaks

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Vikram Naginbhai; Ware, Arthur Gates; Atwood, Corwin Lee; Sattison, Martin Blaine; Hartley, Robert Scott; Hsu, C.

    1999-08-01

    This paper presents our assessment of field experience related to pressurized water reactor (PWR) primary system leaks in terms of their number of rates, how aging affects frequency of leak events, the safety significance of such leaks, industry efforts to reduce leaks, and effectiveness of current leak detection systems. We have reviewed the licensee event reports to identify the events that took place during 1985 to the third quarter of 1996, and reviewed related technical literature and visited PWR plants to analyze these events. Our assessment shows that USNRC licensees have taken effective actions to reduce the number of leak events. One main reason for this decreasing trend was the elimination or reportable leakages from valve stem packing after 1991. Our review of leak events related to vibratory fatigue reveals a statistically significant decreasing trend with age (years of operation), but not in calendar time. Our assessment of worldwide data on leakage caused by thermal fatigue cracking is that the fatigue of aging piping is a safety significant issue. Our review of leak events has identified several susceptible sites in piping having high safety significance; but the inspection of some of these sites is not required by the ASME Code. These sites may be included in the risk-informed inspection programs.

  12. Modeling the Mechanics of Cell Division: Influence of Spontaneous Membrane Curvature, Surface Tension, and Osmotic Pressure

    Directory of Open Access Journals (Sweden)

    Elena Beltrán-Heredia

    2017-05-01

    Full Text Available Many cell division processes have been conserved throughout evolution and are being revealed by studies on model organisms such as bacteria, yeasts, and protozoa. Cellular membrane constriction is one of these processes, observed almost universally during cell division. It happens similarly in all organisms through a mechanical pathway synchronized with the sequence of cytokinetic events in the cell interior. Arguably, such a mechanical process is mastered by the coordinated action of a constriction machinery fueled by biochemical energy in conjunction with the passive mechanics of the cellular membrane. Independently of the details of the constriction engine, the membrane component responds against deformation by minimizing the elastic energy at every constriction state following a pathway still unknown. In this paper, we address a theoretical study of the mechanics of membrane constriction in a simplified model that describes a homogeneous membrane vesicle in the regime where mechanical work due to osmotic pressure, surface tension, and bending energy are comparable. We develop a general method to find approximate analytical expressions for the main descriptors of a symmetrically constricted vesicle. Analytical solutions are obtained by combining a perturbative expansion for small deformations with a variational approach that was previously demonstrated valid at the reference state of an initially spherical vesicle at isotonic conditions. The analytic approximate results are compared with the exact solution obtained from numerical computations, getting a good agreement for all the computed quantities (energy, area, volume, constriction force. We analyze the effects of the spontaneous curvature, the surface tension and the osmotic pressure in these quantities, focusing especially on the constriction force. The more favorable conditions for vesicle constriction are determined, obtaining that smaller constriction forces are required for positive

  13. Ion activation energy delivered to wounds by atmospheric pressure dielectric-barrier discharges: sputtering of lipid-like surfaces

    International Nuclear Information System (INIS)

    Babaeva, Natalia Yu; Kushner, Mark J; Ning Ning; Graves, David B

    2012-01-01

    The application of atmospheric pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. These effects are attributed to production of UV photon fluxes, electric fields and beneficial radicals which intersect with biological reaction chains, and to energetic ions bombarding the surface. In this paper we report on results from a computational investigation of the ion energy and angular distributions (IEADs) in a dielectric-barrier discharge sustained in air incident directly on cell membranes for small dry and wet wounds in human skin. We found that ion energies in excess of 20-30 eV can be delivered onto cell membranes of dry wounds, and up to 60 eV onto the liquid interface of the wet wound. The details of the IEADs depend on the orientation of the cell membrane and on the relative location of the plasma streamer to the wound. Using results from a molecular dynamics simulation of ion sputter probabilities of typical lipid-like material, we show that prolonged exposure of the cell membrane to such IEADs can produce significant carbon removal. (paper)

  14. Ion activation energy delivered to wounds by atmospheric pressure dielectric-barrier discharges: sputtering of lipid-like surfaces

    Science.gov (United States)

    Babaeva, Natalia Yu; Ning, Ning; Graves, David B.; Kushner, Mark J.

    2012-03-01

    The application of atmospheric pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. These effects are attributed to production of UV photon fluxes, electric fields and beneficial radicals which intersect with biological reaction chains, and to energetic ions bombarding the surface. In this paper we report on results from a computational investigation of the ion energy and angular distributions (IEADs) in a dielectric-barrier discharge sustained in air incident directly on cell membranes for small dry and wet wounds in human skin. We found that ion energies in excess of 20-30 eV can be delivered onto cell membranes of dry wounds, and up to 60 eV onto the liquid interface of the wet wound. The details of the IEADs depend on the orientation of the cell membrane and on the relative location of the plasma streamer to the wound. Using results from a molecular dynamics simulation of ion sputter probabilities of typical lipid-like material, we show that prolonged exposure of the cell membrane to such IEADs can produce significant carbon removal.

  15. Assessing actual evapotranspiration via surface energy balance aiming to optimize water and energy consumption in large scale pressurized irrigation systems

    Science.gov (United States)

    Awada, H.; Ciraolo, G.; Maltese, A.; Moreno Hidalgo, M. A.; Provenzano, G.; Còrcoles, J. I.

    2017-10-01

    Satellite imagery provides a dependable basis for computational models that aimed to determine actual evapotranspiration (ET) by surface energy balance. Satellite-based models enables quantifying ET over large areas for a wide range of applications, such as monitoring water distribution, managing irrigation and assessing irrigation systems' performance. With the aim to evaluate the energy and water consumption of a large scale on-turn pressurized irrigation system in the district of Aguas Nuevas, Albacete, Spain, the satellite-based image-processing model SEBAL was used for calculating actual ET. The model has been applied to quantify instantaneous, daily, and seasonal actual ET over high- resolution Landsat images for the peak water demand season (May to September) and for the years 2006 - 2008. The model provided a direct estimation of the distribution of main energy fluxes, at the instant when the satellite overpassed over each field of the district. The image acquisition day Evapotranspiration (ET24) was obtained from instantaneous values by assuming a constant evaporative fraction (Λ) for the entire day of acquisition; then, monthly and seasonal ET were estimated from the daily evapotranspiration (ETdaily) assuming that ET24 varies in proportion to reference ET (ETr) at the meteorological station, thus accounting for day to day variation in meteorological forcing. The comparison between the hydrants water consumption and the actual evapotranspiration, considering an irrigation efficiency of 85%, showed that a considerable amount of water and energy can be saved at district level.

  16. Tilting oil-water contact in the chalk of Tyra Field as interpreted from capillary pressure data

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Rana, M.A.

    2010-01-01

    -trends from logs were compared with normalized water saturation depth-trends predicted from capillary pressure core data. The ten wells lie close to a SW–NE cross section of the field. For the gas–oil contact, a free contact measured in one well corresponds to a practically horizontal contact interpreted from...... of imbibition, where the free water level overlies an interval of residual oil, whereas in the eastern part of the field, the depth-wise trends in normalized water saturation correspond to a situation of drainage. The free water level apparently dips to the east due either to hydrodynamic action or to pressure......The Tyra Field in the central North Sea is located in Palaeogene and Upper Cretaceous chalk. It contains a natural gas zone underlain by an oil leg. Based on analysis of logs and core data from ten wells drilled prior to the field being put into production, normalized water saturation depth...

  17. On the flow magnitude and field-flow alignment at Earth's core surface

    DEFF Research Database (Denmark)

    Finlay, Chris; Amit, H.

    We present a method to estimate the typical magnitude of flow close toEarth's core surface based on observational knowledge of the maingeomagnetic field (MF) and its secular variation (SV), together withprior information concerning field-flow alignment gleaned from numericaldynamo models. An expr......We present a method to estimate the typical magnitude of flow close toEarth's core surface based on observational knowledge of the maingeomagnetic field (MF) and its secular variation (SV), together withprior information concerning field-flow alignment gleaned from numericaldynamo models...... geomagnetic field model gufm1for the interval 1840.0 - 1990.0, the method predicts temporalvariations in flow magnitude similar to those found in earlier studies.The calculations rely primarily on knowledge of the MF and SV spectra;by extrapolating these beyond observed scales the influence of smallscales...

  18. Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

    2008-01-01

    is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-photoemission spectroscopy measurements. This comparison shows that the modified Delta SCF method gives results in close agreement with experiment, significantly closer than the comparable methods. For N2 adsorbed on ruthenium (0001) we map out a two-dimensional part of the potential energy surfaces in the ground state...

  19. Near-field and far-field modeling of scattered surface waves. Application to the apertureless scanning near-field optical microscopy

    International Nuclear Information System (INIS)

    Muller, J.; Parent, G.; Fumeron, S.; Jeandel, G.; Lacroix, D.

    2011-01-01

    The detection of surface waves through scanning near-field optical microscopy (SNOM) is a promising technique for thermal measurements at very small scales. Recent studies have shown that electromagnetic waves, in the vicinity of a scattering structure such as an atomic force microscopy (AFM) tip, can be scattered from near to far-field and thus detected. In the present work, a model based on the finite difference time domain (FDTD) method and the near-field to far-field (NFTFF) transformation for electromagnetic waves propagation is presented. This model has been validated by studying the electromagnetic field of a dipole in vacuum and close to a dielectric substrate. Then simulations for a tetrahedral tip close to an interface are presented and discussed.

  20. Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight: Preliminary PSP Results from Test 581 in the 14- by 22-Foot Subsonic Tunnel

    Science.gov (United States)

    Watkins, Anthony Neal; Leighty, Bradley D.; Lipford, William E.; Wong, Oliver D.; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2011-01-01

    This report will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. This report will also detail possible improvements to the system.

  1. Compilation and analysis of hydrogeological pressure responses to field activities in Olkiluoto during 2006-2009

    International Nuclear Information System (INIS)

    Vaittinen, T.; Pentti, E.

    2013-11-01

    Groundwater flow characteristics provide essential input for the construction and safety assessment of a disposal facility for spent nuclear fuel. On the Olkiluoto site flow connections have been studied in deep drillholes by means of long-term pumping tests, various interference tests, and by interpreting the measured hydraulic heads. This report focuses on the assessment of measured hydraulic heads during 2006-2009. Hydraulic heads have been measured both in open and in packed-off drillholes since 1991. The interpretation of the hydraulic connections is based on observed changes in hydraulic head distribution caused by certain investigation activities on the site. Field activities may increase the head, e.g. drilling, or more typically decrease the head, e.g. flush pumping after drilling, difference flow logging with pumping, and both temporary and currently stable inflows into underground facilities caused by the construction of ONKALO. Processing of the head observations has been developed by determining section-specific corrections for natural fluctuation of the groundwater. The objective of the corrections is to remove natural fluctuation of the groundwater table and sea level, tidal effect, and atmospheric pressure to improve detection of changes in hydraulic head caused by field activities. Time series of observations are compared to schedules of field activities and values for responses are calculated. In addition to temporary responses head drawdown at the end of 2009 is estimated. Analysed responses are mainly related to pumpings from open drillholes and to construction of the access tunnel and the shafts through the hydrogeological HZ19 system until June 2008. Since July 2008 the strongest responses are caused by excavation of the access tunnel and pre-grouting of the shafts through the hydrogeological HZ20 system. Based on the head observations in packed-off drillholes, sub-horizontal hydraulic zones form a layered system at the ONKALO area

  2. Electric field measurements in nanosecond pulse discharges in air over liquid water surface

    Science.gov (United States)

    Simeni Simeni, Marien; Baratte, Edmond; Zhang, Cheng; Frederickson, Kraig; Adamovich, Igor V.

    2018-01-01

    Electric field in nanosecond pulse discharges in ambient air is measured by picosecond four-wave mixing, with absolute calibration by a known electrostatic field. The measurements are done in two geometries, (a) the discharge between two parallel cylinder electrodes placed inside quartz tubes, and (b) the discharge between a razor edge electrode and distilled water surface. In the first case, breakdown field exceeds DC breakdown threshold by approximately a factor of four, 140 ± 10 kV cm-1. In the second case, electric field is measured for both positive and negative pulse polarities, with pulse durations of ˜10 ns and ˜100 ns, respectively. In the short duration, positive polarity pulse, breakdown occurs at 85 kV cm-1, after which the electric field decreases over several ns due to charge separation in the plasma, with no field reversal detected when the applied voltage is reduced. In a long duration, negative polarity pulse, breakdown occurs at a lower electric field, 30 kV cm-1, after which the field decays over several tens of ns and reverses direction when the applied voltage is reduced at the end of the pulse. For both pulse polarities, electric field after the pulse decays on a microsecond time scale, due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Measurements 1 mm away from the discharge center plane, ˜100 μm from the water surface, show that during the voltage rise, horizontal field component (Ex ) lags in time behind the vertical component (Ey ). After breakdown, Ey is reduced to near zero and reverses direction. Further away from the water surface (≈0.9 mm), Ex is much higher compared to Ey during the entire voltage pulse. The results provide insight into air plasma kinetics and charge transport processes near plasma-liquid interface, over a wide range of time scales.

  3. Effect of skin surface lipid on the skin permeation of lidocaine from pressure sensitive adhesives.

    Science.gov (United States)

    Cheng, Y H; Hosoya, O; Sugibayashi, K; Morimoto, Y

    1994-12-01

    Pressure sensitive adhesives (PSA) tapes containing different concentrations of lidocaine were prepared by a general casting method using styrene-isoprene-styrene block copolymer, and the in vitro skin permeation of lidocaine from each tape was evaluated using diffusion cell and excised hairless rat skin. The skin permeation was proportionally increased by up to 40% lidocaine in the PSA tape and did not change after this concentration. Although the bending point of the steady-state flux via skin concentration curve was found at 40%, saturated concentration or solubility of lidocaine in the tape was estimated to be about 20% by differential scanning calorimetry (DSC) measurement. In addition, the steady-state flux of lidocaine through skin from water or silicone fluid suspension (92 or 120 micrograms/cm2.h, respectively) was very similar to those of 40, 50 and 60% tapes (105, 101 and 112 micrograms/cm2.h, respectively). Decrease in the concentration in tapes during the permeation experiment explained only part of these phenomena. To analyze them further, the drug free PSA tape with or without (control) skin surface lipid was affixed to 50% lidocaine PSA tape for 48 h, and the amount of lidocaine crystal in the layered tapes was measured by DSC. The amount was found to be lower in the lipid-containing tape than in the lipid-free tape, suggesting that skin surface lipid can dissolve lidocaine crystal or solid in PSA tape to decrease its thermodynamic activity. Thus it is important to follow the concentration and thermodynamic activity of lidocaine in PSA tape, skin and the interface between the two layers to exactly assess its skin permeation flux.

  4. Singular surfaces in the open field line region of a diverted tokamak

    International Nuclear Information System (INIS)

    Reiman, A.

    1995-05-01

    The structure of the open field lines of a slightly nonaxisymmetric, poloidally diverted tokamak is explored by numerical integration of the field line equations for a simple model field. In practice, the nonaxisymmetry could be produced self-consistently by the nonlinear evolution of a free-boundary MHD mode, or it could be produced by field errors, or it could be imposed externally by design. In the presence of a nonaxisymmetric perturbation, the tokamak is shown to develop open field line regions of differing topology separated by singular surfaces. It is argued that the singular surfaces can be expected to play a role analogous to that of rational toroidal flux surfaces, in terms of constraining ideal MHD perturbations and thus constraining the free-energy that can be tapped by ideal MHD instabilities. The possibility of active control of free-boundary instabilities by means of currents driven on the open singular surfaces, which are directly accessible from the divertor plates, is discussed. Also discussed is the possibility of early detection of imminent disruptions through localized measurement of the singular surface currents

  5. Modelling of Lunar Dust and Electrical Field for Future Lunar Surface Measurements

    Science.gov (United States)

    Lin, Yunlong

    Modelling of the lunar dust and electrical field is important to future human and robotic activities on the surface of the moon. Apollo astronauts had witnessed the maintaining of micron- and millimeter sized moon dust up to meters level while walked on the surface of the moon. The characterizations of the moon dust would enhance not only the scientific understanding of the history of the moon but also the future technology development for the surface operations on the moon. It has been proposed that the maintaining and/or settlement of the small-sized dry dust are related to the size and weight of the dust particles, the level of the surface electrical fields on the moon, and the impaction and interaction between lunar regolith and the solar particles. The moon dust distributions and settlements obviously affected the safety of long term operations of future lunar facilities. For the modelling of the lunar dust and the electrical field, we analyzed the imaging of the legs of the moon lander, the cover and the footwear of the space suits, and the envelope of the lunar mobiles, and estimated the size and charges associated with the small moon dust particles, the gravity and charging effects to them along with the lunar surface environment. We also did numerical simulation of the surface electrical fields due to the impaction of the solar winds in several conditions. The results showed that the maintaining of meters height of the micron size of moon dust is well related to the electrical field and the solar angle variations, as expected. These results could be verified and validated through future on site and/or remote sensing measurements and observations of the moon dust and the surface electrical field.

  6. Highway-railway at-grade crossing structures : trackbed and surface pressure measurements and assessments.

    Science.gov (United States)

    2009-05-01

    Techniques are described for installing instrumentation within highway/railway crossings - to measure vertical pressures under moving highway and railway loadings - using earth pressure cells. Also, techniques are described for installing instrumenta...

  7. Specificity for field enumeration of Escherichia coli in tropical surface waters

    DEFF Research Database (Denmark)

    Jensen, Peter Kjær Mackie; Aalbaek, B; Aslam, R

    2001-01-01

    In remote rural areas in developing countries, bacteriological monitoring often depends on the use of commercial field media. This paper evaluates a commercial field medium used for the enumeration of Escherichia coli in different surface waters under primitive field conditions in rural Pakistan....... In order to verify the field kit, 117 presumptive E. coli isolates have been tested, finding a specificity of only 40%. By excluding some strains based on colony colours, the calculated specificity could be increased to 65%. Thus, it is suggested that prior to use in a tropical environment, the specificity...... of any commercial medium used should be tested with representative tropical isolates, in order to increase the specificity....

  8. Specificity for field enumeration of Escherichia coli in tropical surface waters

    DEFF Research Database (Denmark)

    Jensen, Peter Kjær Mackie; Aalbaek, B; Aslam, R

    2001-01-01

    In remote rural areas in developing countries, bacteriological monitoring often depends on the use of commercial field media. This paper evaluates a commercial field medium used for the enumeration of Escherichia coli in different surface waters under primitive field conditions in rural Pakistan....... In order to verify the field kit, 117 presumptive E. coli isolates have been tested, finding a specificity of only 40%. By excluding some strains based on colony colours, the calculated specificity could be increased to 65%. Thus, it is suggested that prior to use in a tropical environment, the specificity...

  9. Quantum tricritical point in the temperature-pressure-magnetic field phase diagram of CeTiGe3

    Science.gov (United States)

    Kaluarachchi, Udhara S.; Taufour, Valentin; Bud'ko, Sergey L.; Canfield, Paul C.

    2018-01-01

    We report the temperature-pressure-magnetic-field phase diagram of the ferromagnetic Kondo-lattice CeTiGe3 determined by means of electrical resistivity measurements. Measurements up to ˜5.8 GPa reveal a rich phase diagram with multiple phase transitions. At ambient pressure, CeTiGe3 orders ferromagnetically at TC=14 K. Application of pressure suppresses TC, but a pressure-induced ferromagnetic quantum criticality is avoided by the appearance of two new successive transitions for p >4.1 GPa that are probably antiferromagnetic in nature. These two transitions are suppressed under pressure, with the lower-temperature phase being fully suppressed above 5.3 GPa. The critical pressures for the presumed quantum phase transitions are p1≅4.1 GPa and p2≅5.3 GPa. Above 4.1 GPa, application of magnetic field shows a tricritical point evolving into a wing-structure phase with a quantum tricritical point at 2.8 T at 5.4 GPa, where the first-order antiferromagnetic-ferromagnetic transition changes into the second-order antiferromagnetic-ferromagnetic transition.

  10. A nurse-led randomised trial of pressure-relieving support surfaces.

    Science.gov (United States)

    Nelson, E Andrea; Nixon, Jane; Mason, Su; Barrow, Helen; Phillips, Angela; Cullum, Nicky

    2003-05-01

    A nurse-led trial is currently collecting data comparing interventions for the prevention and treatment of pressure ulcers. The aim is to provide reliable guidance on the relative merits of alternating-pressure mattresses and overlays for people at moderate to high risk of pressure ulceration. This paper outlines the main objectives, methodology and progress of the study.

  11. Development of a commercial Transducer for Measuring Pressure and Friction on the Model Die Surface

    DEFF Research Database (Denmark)

    Andersen, Claus Bo; Ravn, Bjarne Gottlieb; Wanheim, Tarras

    2001-01-01

    deflection in the tool causes incorrect shape of the final component. The dinemsions of the die-cavity have to be corrected taking into account die deflection due to the high internal pressure. The modelling material technique is suitable for measuring internal pressure, but so far only a transducer...... to measure normal pressure has been available....

  12. Pressure and surface tension of soild-liquid interface using Tarazona density functional theory

    Directory of Open Access Journals (Sweden)

    M. M.

    2000-12-01

    Full Text Available   The weighted density functional theory proposed by Tarazona is applied to study the solid-liquid interface. In the last two decades the weighted density functional became a useful tool to consider the properties of inhomogeneous liquids. In this theory, the role of the size of molecules or the particles of which the matter is composed, was found to be important. In this resarch we study a hard sphere fluid beside a hard wall. For this study the liquid is an inhomogeneous system. We use the definition of the direct correlation function as a second derivative of free energy with respect to the density. We use this definition and the definition of the weighting function, then we minimize the grand potential with respect to the density to get the Euler Lagrange equation and we obtain an integral equation to find the inhomogeneous density profile. The obtained density profile as a function of the distance from the wall, for different bulk density is plotted in three dimensions. We also calculate the pressure and compare it with the Carnahan-starling results, and finally we obtained the surface tension at liquid-solid interface and compared it with the results of Monte Carlo simulation.

  13. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    International Nuclear Information System (INIS)

    Marinov, Daniil; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine; Guerra, Vasco

    2013-01-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1–5 Torr and discharge currents ∼40–120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O 3 * , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O 3 * is strongly coupled with those of atomic oxygen and O 2 (a 1 Δ g ) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established. (paper)

  14. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    Science.gov (United States)

    Marinov, Daniil; Guerra, Vasco; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine

    2013-10-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1-5 Torr and discharge currents ˜40-120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O_3^{*} , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O_3^{*} is strongly coupled with those of atomic oxygen and O2(a 1Δg) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established.

  15. Optimizing pressurized liquid extraction of microbial lipids using the response surface method.

    Science.gov (United States)

    Cescut, J; Severac, E; Molina-Jouve, C; Uribelarrea, J-L

    2011-01-21

    Response surface methodology (RSM) was used for the determination of optimum extraction parameters to reach maximum lipid extraction yield with yeast. Total lipids were extracted from oleaginous yeast (Rhodotorula glutinis) using pressurized liquid extraction (PLE). The effects of extraction parameters on lipid extraction yield were studied by employing a second-order central composite design. The optimal condition was obtained as three cycles of 15 min at 100°C with a ratio of 144 g of hydromatrix per 100 g of dry cell weight. Different analysis methods were used to compare the optimized PLE method with two conventional methods (Soxhlet and modification of Bligh and Dyer methods) under efficiency, selectivity and reproducibility criteria thanks to gravimetric analysis, GC with flame ionization detector, High Performance Liquid Chromatography linked to Evaporative Light Scattering Detector (HPLC-ELSD) and thin-layer chromatographic analysis. For each sample, the lipid extraction yield with optimized PLE was higher than those obtained with referenced methods (Soxhlet and Bligh and Dyer methods with, respectively, a recovery of 78% and 85% compared to PLE method). Moreover, the use of PLE led to major advantages such as an analysis time reduction by a factor of 10 and solvent quantity reduction by 70%, compared with traditional extraction methods. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Effects of Surface Roughness, Oxidation, and Temperature on the Emissivity of Reactor Pressure Vessel Alloys

    Energy Technology Data Exchange (ETDEWEB)

    King, J. L. [University of Wisconsin–Madison, Department of Engineering Physics, Madison, Wisconsin; Jo, H. [University of Wisconsin–Madison, Department of Engineering Physics, Madison, Wisconsin; Tirawat, R. [National Renewable Energy Laboratory, Concentrating Solar Power Group, Golden, Colorado; Blomstrand, K. [University of Wisconsin–Madison, Department of Engineering Physics, Madison, Wisconsin; Sridharan, K. [University of Wisconsin–Madison, Department of Engineering Physics, Madison, Wisconsin

    2017-08-31

    Thermal radiation will be an important mode of heat transfer in future high-temperature reactors and in off-normal high-temperature scenarios in present reactors. In this work, spectral directional emissivities of two reactor pressure vessel (RPV) candidate materials were measured at room temperature after exposure to high-temperature air. In the case of SA508 steel, significant increases in emissivity were observed due to oxidation. In the case of Grade 91 steel, only very small increases were observed under the tested conditions. Effects of roughness were also investigated. To study the effects of roughening, unexposed samples of SA508 and Grade 91 steel were roughened via one of either grinding or shot-peening before being measured. Significant increases were observed only in samples having roughness exceeding the roughness expected of RPV surfaces. While the emissivity increases for SA508 from oxidation were indeed significant, the measured emissivity coefficients were below that of values commonly used in heat transfer models. Based on the observed experimental data, recommendations for emissivity inputs for heat transfer simulations are provided.

  17. Botswana water and surface energy balance research program. Part 1: Integrated approach and field campaign results

    Science.gov (United States)

    Vandegriend, A. A.; Owe, M.; Vugts, H. F.; Ramothwa, G. K.

    1992-01-01

    The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. Results of the first part of the program (Botswana 1) which ran from 1 Jan. 1988 - 31 Dec. 1990 are summarized. Botswana 1 consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components in general are described and activities performed during the surface energy modeling component including the extensive field campaign are summarized. The results of the passive microwave component are summarized. The key of the field campaign was a multilevel approach, whereby measurements by various similar sensors were made at several altitudes and resolution. Data collection was performed at two adjacent sites of contrasting surface character. The following measurements were made: micrometeorological measurements, surface temperatures, soil temperatures, soil moisture, vegetation (leaf area index and biomass), satellite data, aircraft data, atmospheric soundings, stomatal resistance, and surface emissivity.

  18. Negative pressures in full-scale distribution system: field investigation, modelling, estimation of intrusion volumes and risk for public health

    Directory of Open Access Journals (Sweden)

    M. C. Besner

    2010-07-01

    Full Text Available Various investigations encompassing microbial characterization of external sources of contamination (soil and trenchwater surrounding water mains, flooded air-valve vaults, field pressure monitoring, and hydraulic and transient analyses were conducted in the same distribution system where two epidemiological studies showing an increase in gastrointestinal illness for people drinking tap water were conducted in the 1990's. Interesting results include the detection of microorganisms indicators of fecal contamination in all external sources investigated but at a higher frequency in the water from flooded air-valve vaults, and the recording of 18 negative pressure events in the distribution system during a 17-month monitoring period. Transient analysis of this large and complex distribution system was challenging and highlighted the need to consider field pressure data in the process.

  19. Consumer perception of the use of high-pressure processing and pulsed electric field technologies in food production

    DEFF Research Database (Denmark)

    Nielsen, Henriette Boel; Sonne, Anne-Mette; Grunert, Klaus G.

    2009-01-01

    on consumer attitudes towards high-pressure processing (HPP) and pulsed electric field (PEF) processing of food was carried out. In all 97 adults between 20 and 71 years of age participated in 12 focus groups conducted in Slovenia, Hungary, Serbia, Slovakia, Norway and Denmark using a common guideline...

  20. High pressure and high magnetic field behaviour of free and donor-bound-exciton photoluminescence in InSe

    Energy Technology Data Exchange (ETDEWEB)

    Millot, M.; Broto, J.M.; Leotin, J. [Laboratoire National des Champs Magnetiques Pulses, Universite de Toulouse (France); Gilliland, S.; Segura, A. [ICMUV-Malta Consolider Team, Universitat de Valencia, Valencia (Spain); Gonzalez, J. [Centro de Estudio de Semiconductores, Universidad de Los Andes, Merida (Venezuela); DCITIMAC-Malta Consolider Team, Universidad de Cantabria, Santander (Spain); Chevy, A. [Institut de Mineralogie et de Physique des Milieux Condenses, CNRS, Universite Pierre et Marie Curie Paris 6, 75015 Paris (France)

    2009-03-15

    We report here first magneto-photoluminescence investigations under high pressure up to 6 GPa on III-VI layered semiconductor InSe. Both diamagnetism and magnetic field induced gap opening driven by Landau quantization became observable by using a 60 T pulsed magnet. The pressure-induced enhancement of the diamagnetic coefficient is consistent with the increase of the dielectric constant under pressure while the evolution of the linear coefficient is consistent with a slight increase of the electron effective mass up to 4 GPa and a direct-to-indirect conduction-band crossover around that pressure. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)