WorldWideScience

Sample records for calculating near-field pressures

  1. Efficient Calculation of Near Fields in the FDTD Method

    DEFF Research Database (Denmark)

    Franek, Ondrej

    2011-01-01

    When calculating frequency-domain near fields by the FDTD method, almost 50 % reduction in memory and CPU operations can be achieved if only E-fields are stored during the main time-stepping loop and H-fields computed later. An improved method of obtaining the H-fields from Faraday's Law is...

  2. Optical measurement of acoustic radiation pressure of the near-field acoustic levitation through transparent object

    CERN Document Server

    Nakamura, Satoshi; Sasao, Yasuhiro; Katsura, Kogure; Naoki, Kondo

    2013-01-01

    It is known that macroscopic objects can be levitated for few to several hundred micrometers by near-field acoustic field and this phenomenon is called near-field acoustic levitation (NFAL). Although there are various experiments conducted to measure integrated acoustic pressure on the object surface, up to now there was no direct method to measure pressure distribution. In this study we measured the acoustic radiation pressure of the near-field acoustic levitation via pressure-sensitive paint.

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

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    of particle velocity measurements and combined pressure-velocity measurements in NAH, the relation between the near-field and the far-field radiation from sound sources via the supersonic acoustic intensity, and finally, the reconstruction of sound fields using rigid spherical microphone arrays. Measurement...... 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...

  4. Fast Near-Field Calculation for Volume Integral Equations for Layered Media

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Meincke, Peter; Breinbjerg, Olav

    2005-01-01

    An efficient technique based on the Fast Fourier Transform (FFT) for calculating near-field scattering by dielectric objects in layered media is presented. A higher or-der method of moments technique is employed to solve the volume integral equation for the unknown induced volume current density....... Afterwards, the scattered electric field can be easily computed at a regular rectangular grid on any horizontal plane us-ing a 2-dimensional FFT. This approach provides significant speedup in the near-field calculation in comparison to a straightforward numerical evaluation of the ra-diation integral since...

  5. Comparison of two numerical modelling codes for hydraulic and transport calculations in the near-field

    Energy Technology Data Exchange (ETDEWEB)

    Kalin, J., E-mail: jan.kalin@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Petkovsek, B., E-mail: borut.petkovsek@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Montarnal, Ph., E-mail: philippe.montarnal@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Genty, A., E-mail: alain.genty@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Deville, E., E-mail: estelle.deville@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Krivic, J., E-mail: jure.krivic@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia); Ratej, J., E-mail: joze.ratej@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia)

    2011-04-15

    In the past years the Slovenian Performance Analysis/Safety Assessment team has performed many generic studies for the future Slovenian low and intermediate level waste repository, most recently a Special Safety Analysis for the Krsko site. The modelling approach was to split the problem into three parts: near-field (detailed model of the repository), far-field (i.e., geosphere) and biosphere. In the Special Safety Analysis the code used to perform the near-field calculations was Hydrus2D. Recently the team has begun a cooperation with the French Commisariat al'Energie Atomique/Saclay (CEA/Saclay) and, as a part of this cooperation, began investigations into using the Alliances numerical platform for near-field calculations in order to compare the overall approach and calculated results. The article presents the comparison between these two codes for a silo-type repository that was considered in the Special Safety Analysis. The physical layout and characteristics of the repository are presented and a hydraulic and transport model of the repository is developed and implemented in Alliances. Some analysis of sensitivity to mesh fineness and to simulation timestep has been preformed and is also presented. The compared quantity is the output flux of radionuclides on the boundary of the model. Finally the results from Hydrus2D and Alliances are compared and the differences and similarities are commented.

  6. 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 recen...... generated by sources on the two sides of the hologram plane is also examined....

  7. A submerged singularity method for calculating potential flow velocities at arbitrary near-field points

    Science.gov (United States)

    Maskew, B.

    1976-01-01

    A discrete singularity method has been developed for calculating the potential flow around two-dimensional airfoils. The objective was to calculate velocities at any arbitrary point in the flow field, including points that approach the airfoil surface. That objective was achieved and is demonstrated here on a Joukowski airfoil. The method used combined vortices and sources ''submerged'' a small distance below the airfoil surface and incorporated a near-field subvortex technique developed earlier. When a velocity calculation point approached the airfoil surface, the number of discrete singularities effectively increased (but only locally) to keep the point just outside the error region of the submerged singularity discretization. The method could be extended to three dimensions, and should improve nonlinear methods, which calculate interference effects between multiple wings, and which include the effects of force-free trailing vortex sheets. The capability demonstrated here would extend the scope of such calculations to allow the close approach of wings and vortex sheets (or vortices).

  8. Calculation of Calibration Functions and Explosive Aftershock Magnitudes in the Near Field

    Institute of Scientific and Technical Information of China (English)

    Li Xuezheng; Wang Haijun; Lei Jun

    2003-01-01

    The current calibration function used in calculating the magnitude of natural earthquakes within 5km is a constant; a fact that causes several serious difficulties for the calculation of the magnitude of small and shallow-focus earthquakes. According to the attenuation law of explosions and the propagation theory of elastic waves, the calibration function is calculated for near field quakes from 0km to 5km. Magnitudes of two aftershock sequences are calculated.The magnitudes of most explosion earthquakes are small, ranging mainly from magnitude 0.5 to 1.0. The M-t chart of the explosive aftershocks is completely different from that of strong earthquake aftershocks. It not only shows positive columnar lines indicating large magnitudes but also short negative columnar lines indicating small magnitudes.

  9. Ocean-bottom Pressure Signals as Potential Identifiers of Tsunami Earthquakes in the Near Field

    Science.gov (United States)

    Salaree, A.; Okal, E. A.

    2015-12-01

    The real-time detection of "tsunami earthquakes" remains a challenge, especially in the near field. These events are characterized by an anomalously slow seismic rupture, with their true long-period seismic moment, and hence, tsunami potential, deceptively concealed from short-period waves and in particular felt accelerations. In the context of the deployment of long-period ocean-bottom sensors in epicentral areas, we explore simple but robust ways to quantify source parameters which could potentially lead to the real-time identification of tsunami earthquakes in the near field. We use records of 2011 Tohoku aftershocks on the JAMSTEC stations deployed off the coast of Japan in the wake of the mainshock. Because seismic phases are not resolvable at short distances, we simply consider an integrated measurement Ω of the square of pressure variations, sharing the philosophy of Boatwright and Choy's (1986) seismic energy, and compare this parameter, scaled to seismic moment, with other discriminants, such as Newman and Okal's (1998) energy-to-moment ratio, Θ, Okal et al.'s (2002) T-wave parameter Γ, or Okal's (2013) parameter Φ combining (in the far field) body-wave duration and energy. We also consider the duration of the pressure signal, and examine its relation to Ω.

  10. 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 hol

  11. A GPU-based Calculation Method for Near Field Effects of Cherenkov Radiation Induced by Ultra High Energy Cosmic Neutrinos

    CERN Document Server

    Hu, Chia-Yu; Chen, Pisin

    2010-01-01

    The radio approach for detecting the ultra-high energy cosmic neutrinos has become a mature field. The Cherenkov signals in radio detection are originated from the charge excess of particle showers due to Askaryan effect. The conventional way of calculating the Cherenkov pulses by making Fraunhofer approximation fails when the sizes of the elongated showers become comparable with the detection distances. We present a calculation method of Cherenkov pulses based on the finite-difference time-domain (FDTD) method, and attain a satisfying effeciency via the GPU- acceleration. Our method provides a straightforward way of the near field calculation, which would be important for ultra high energy particle showers, especailly the electromagnetic showers induced by the high energy leptons produced in the neutrino charge current interactions.

  12. A new method to calculate near-field radiation excited by heterogeneous fault rupture

    Institute of Scientific and Technical Information of China (English)

    SHANG Xue-feng; LIU Qi-ming; ZHANG Hai-ming; CHEN Xiao-fei

    2007-01-01

    This paper derives from the representation theory the formula for calculating the radiation excited by heterogeneous fault rupture based on box-like discretization scheme. Preliminary validation indicates that our algorithm has very high computation precision and efficiency; therefore, it is a very practical tool to investigate strong ground motion problems. Additionally, the equations given in this study can also be used to invert the fault rupture process.

  13. Near-field heat transfer at the spent fuel test-climax: a comparison of measurements and calculations

    International Nuclear Information System (INIS)

    The Spent Fuel Test in the Climax granitic stock at the DOE Nevada Test Site is a test of the feasibility of storage and retrieval of spent nuclear reactor fuel in a deep geologic environment. Eleven spent fuel elements, together with six thermally identical electrical resistance heaters and 20 peripheral guard heaters, are emplaced 420 m below surface in a three-drift test array. This array was designed to simulate the near-field effects of thousands of canisters of nuclear waste and to evaluate the effects of heat alone, and heat plus ionizing radiation on the rock. Thermal calculations and measurements are conducted to determine thermal transport from the spent fuel and electrical resistance heaters. Calculations associated with the as-built Spent Fuel Test geometry and thermal source histories are presented and compared with thermocouple measurements made throughout the test array. Comparisons in space begin at the spent fuel canister and include the first few metres outside the test array. Comparisons in time begin at emplacement and progress through the first year of thermal loading in this multi-year test

  14. Near-field correction in the first-principles calculations by the exact two-center expansion for the inverse of the distance

    International Nuclear Information System (INIS)

    We propose a method to deal with the so-called near-field corrections to the solution of the Poisson equation for full-potential first-principles calculations using the exact two-center expansion for the inverse of the distance between two points. It is demonstrated that the method gives a very satisfying solution to the Poisson equation for plane-wave charge densities which can be solved analytically. The present method gives reasonable total energy for lattice distortions where the conventional multipole expansion gives large errors. (paper)

  15. Hydraulic calculation of pressure pipes

    OpenAIRE

    Mikhalev, M. A.

    2012-01-01

    In the present time there is only one classic method for hydraulic calculation of pressure pipes. In it fluid flow velocity and pipeline diameter are considered as given values.The paper proposes a procedure for physical modeling and hydraulic calculation of pressure pipes, based on the theory of similarity. Methods for obtaining similarity criteria from combinations of similarity numbers were discussed. Similarity numbers and criteria and criteria equations were defined.

  16. The calculation of pressure vessels

    International Nuclear Information System (INIS)

    The calculation guidelines of the Arbeitsgemeinschaft Druckbehaelter (task group for pressure vessels) have been revised with the following objective: conversion to international standards (SI), adaption to the latest state of guidelines for production and testing, revision of the contents of individual regulations. Another target of the cooperating interest groups of producers, operators, and supervisory bodies was a harmonization of the approaches for calculation with other German guidelines, in particular the Technische Regeln fuer Dampfkessel (technical regulations for steam boilers). (orig./RW)

  17. ITER Port Interspace Pressure Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Carbajo, Juan J [ORNL; Van Hove, Walter A [ORNL

    2016-01-01

    The ITER Vacuum Vessel (VV) is equipped with 54 access ports. Each of these ports has an opening in the bioshield that communicates with a dedicated port cell. During Tokamak operation, the bioshield opening must be closed with a concrete plug to shield the radiation coming from the plasma. This port plug separates the port cell into a Port Interspace (between VV closure lid and Port Plug) on the inner side and the Port Cell on the outer side. This paper presents calculations of pressures and temperatures in the ITER (Ref. 1) Port Interspace after a double-ended guillotine break (DEGB) of a pipe of the Tokamak Cooling Water System (TCWS) with high temperature water. It is assumed that this DEGB occurs during the worst possible conditions, which are during water baking operation, with water at a temperature of 523 K (250 C) and at a pressure of 4.4 MPa. These conditions are more severe than during normal Tokamak operation, with the water at 398 K (125 C) and 2 MPa. Two computer codes are employed in these calculations: RELAP5-3D Version 4.2.1 (Ref. 2) to calculate the blowdown releases from the pipe break, and MELCOR, Version 1.8.6 (Ref. 3) to calculate the pressures and temperatures in the Port Interspace. A sensitivity study has been performed to optimize some flow areas.

  18. Near Field Communication Applications

    OpenAIRE

    Akman, Özgen

    2015-01-01

    Near Field Communication (NFC) is a short-range, low power contactless communication between NFC-enabled devices that are held in the closed proximity to each other. NFC technology has been moving rapidly from its initial application areas of mobile payment services and contactless ticketing to the diversity of new areas. Three specific NFC tags highlighted in the thesis have different structures in terms of memory, security and usage in different applications. NFC information tags exploit th...

  19. Near field communications handbook

    CERN Document Server

    Ahson, Syed A; Furht, Borko

    2011-01-01

    Near Field Communication, or NFC, is a short-range high frequency wireless communication technology that enables the exchange of data between devices over about a decimeter. The technology is a simple extension of the ISO 14443 proximity-card standard (contact less card, RFID) that combines the interface of a smart card and a reader into a single device with practical implications. A complete reference for NFC, this handbook provides technical information about all aspects of NFC, as well as applications. It covers basic concepts as well as research grade material and includes a discussion of

  20. Near field heat transfer in superlattices

    Science.gov (United States)

    Esquivel-Sirvent, Raul

    2015-03-01

    I present a theoretical calculation of the near field heat transfer between super lattices made of alternative layers of both metallic and semiconducting materials. The calculation of the near field transfer requires the knowledge of the reflectivities, that are obtained by calculating the surface impedance of the super lattice. Depending on the periodicity of the lattice and the dielectric function of the materials the near field heat transfer can be modulated or engineered. Additional control on the heat transfer is achieved by introducing defects in the superlattice. The results are extended to include photonic hypercrystals that effectively behave like a hyperbolic metamaterial even in the near field (1), where the tuning of the heat transfer is modified by Partial Support from DGAPA-UNAM project IN 111214.

  1. Thermal infrared near-field spectroscopy.

    Science.gov (United States)

    Jones, Andrew C; Raschke, Markus B

    2012-03-14

    Despite the seminal contributions of Kirchhoff and Planck describing far-field thermal emission, fundamentally distinct spectral characteristics of the electromagnetic thermal near-field have been predicted. However, due to their evanescent nature their direct experimental characterization has remained elusive. Combining scattering scanning near-field optical microscopy with Fourier-transform spectroscopy using a heated atomic force microscope tip as both a local thermal source and scattering probe, we spectroscopically characterize the thermal near-field in the mid-infrared. We observe the spectrally distinct and orders of magnitude enhanced resonant spectral near-field energy density associated with vibrational, phonon, and phonon-polariton modes. We describe this behavior and the associated distinct on- and off-resonance nanoscale field localization with model calculations of the near-field electromagnetic local density of states. Our results provide a basis for intrinsic and extrinsic resonant manipulation of optical forces, control of nanoscale radiative heat transfer with optical antennas, and use of this new technique of thermal infrared near-field spectroscopy for broadband chemical nanospectroscopy. PMID:22280474

  2. A comparison of inverse boundary element method and near-field acoustical holography

    DEFF Research Database (Denmark)

    Schuhmacher, Andreas; Hald, Jørgen; Saemann, E.-U.

    1999-01-01

    An inverse boundary element method (IBEM) is used to estimate the surface velocity of a rolling tyre from measurements of the near-field pressure. Subsequently, the sound pressure is calculated over a finite plane surface next to the tyre from the reconstructed velocity field on the tyre surface...

  3. Calculation of the inventory and near-field release rates of radioactivity from neutron-activated metal parts discharged from the high flux isotope reactor and emplaced in solid waste storage area 6 at Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Emplacement of contaminated reactor components involves disposal in lined and unlined auger holes in soil above the water table. The radionuclide inventory of disposed components was calculated. Information on the composition and weight of the components, as well as reasonable assumptions for the neutron flux fueling use, the time of neutron exposure, and radioactive decay after discharge, were employed in the inventory calculation. Near-field release rates of 152Eu, 154Eu, and 155Eu from control plates and cylinders were calculated for 50 years after emplacement. Release rates of the europium isotopes were uncertain. Two release-rate-limiting models were considered and a range of reasonable values were assumed for the time-to-failure of the auger-hole linear and aluminum cladding and europium solubility in SWSA-6 groundwater. The bounding europium radionuclide near-field release rates peaked at about 1.3 Ci/year total for /sup 152,154,155/Eu in 1987 for the lower bound, and at about 420 Ci/year in 1992 for the upper bound. The near-field release rates of 55Fe, 59Ni, 60Co, and 63Ni from stainless steel and cobalt alloy components, as well as of 10Be, 41Ca, and 55Fe from beryllium reflectors, were calculated for the next 100 years, assuming bulk waste corrosion was the release-rate-limiting step. Under the most conservative assumptions for the reflectors, the current (1986) total radionuclide release rate was calculated to be about 1.2 x 10-4 Ci/year, decreasing by 1992 to a steady release of about 1.5 x 10-5 Ci/year due primarily to 41Ca. 50 refs., 13 figs., 8 tabs

  4. Calculation of the inventory and near-field release rates of radioactivity from neutron-activated metal parts discharged from the high flux isotope reactor and emplaced in solid waste storage area 6 at Oak Ridge National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Kelmers, A.D.; Hightower, J.R.

    1987-05-01

    Emplacement of contaminated reactor components involves disposal in lined and unlined auger holes in soil above the water table. The radionuclide inventory of disposed components was calculated. Information on the composition and weight of the components, as well as reasonable assumptions for the neutron flux fueling use, the time of neutron exposure, and radioactive decay after discharge, were employed in the inventory calculation. Near-field release rates of /sup 152/Eu, /sup 154/Eu, and /sup 155/Eu from control plates and cylinders were calculated for 50 years after emplacement. Release rates of the europium isotopes were uncertain. Two release-rate-limiting models were considered and a range of reasonable values were assumed for the time-to-failure of the auger-hole linear and aluminum cladding and europium solubility in SWSA-6 groundwater. The bounding europium radionuclide near-field release rates peaked at about 1.3 Ci/year total for /sup 152,154,155/Eu in 1987 for the lower bound, and at about 420 Ci/year in 1992 for the upper bound. The near-field release rates of /sup 55/Fe, /sup 59/Ni, /sup 60/Co, and /sup 63/Ni from stainless steel and cobalt alloy components, as well as of /sup 10/Be, /sup 41/Ca, and /sup 55/Fe from beryllium reflectors, were calculated for the next 100 years, assuming bulk waste corrosion was the release-rate-limiting step. Under the most conservative assumptions for the reflectors, the current (1986) total radionuclide release rate was calculated to be about 1.2 x 10/sup -4/ Ci/year, decreasing by 1992 to a steady release of about 1.5 x 10/sup -5/ Ci/year due primarily to /sup 41/Ca. 50 refs., 13 figs., 8 tabs.

  5. TBM pressure models: calculation tools

    OpenAIRE

    Gerheim Souza Dias, Tiago; Bezuijen, Adam

    2015-01-01

    Mechanized tunnel construction in soft ground has evolved significantly over the last 20 years, especially on the matter of settlement control. This was achieved by guiding the TBM operation to control the main factors that induce soil displacements, namely the face pressure and the closure of the soil-lining void. Nowadays, TBMs can be operated within strict serviceability requirements. However, several mechanisms of the excavation cycle are still not taken into account when estimating the i...

  6. Terahertz near-field microspectroscopy

    NARCIS (Netherlands)

    Knab, J.R.; Adam, A.J.L.; Chakkittakandy, R.; Planken, P.C.M.

    2010-01-01

    Using near-field, terahertz time-domain spectroscopy (THz-TDS), we investigate how the addition of a dielectric material into a subwavelength-diameter, cylindrical waveguide affects its transmission properties. The THz electric near-field is imaged with deep subwavelength resolution as it emerges fr

  7. DECOVALEX-THMC Project. Task A. Influence of near field coupled THM phenomena on the performance of a spent fuel repository. Report of Task A1: Preliminary scoping calculations

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Son (ed.) [Canadian Nuclear Safety Commission (Canada); Lanru Jing (ed.) [Royal Institute of Technology, Stockholm (Sweden); Boergesson, Lennart [Clay Technology AB, Lund (Sweden); Chijimatzu, Masakazu [Hazama Corporation (Japan); Jussila, Petri [Helsinki Univ. of Technology, Helsinki (Finland); Rutqvist, Jonny [Lawrence Berkeley National Laboratory CA (United States)

    2007-02-15

    The DECOVALEX-THMC project is an ongoing international co-operative project that was stared in 2004 to support the development of mathematical models of coupled Thermal (T), Hydrological (H), Mechanical (M) and Chemical (C) processes in geological media for siting potential nuclear fuel waste repositories. The general objective is to characterise and evaluate the coupled THMC processes in the near field and far field of a geological repository and to assess their impact on performance assessment: - during the three phases of repository development: excavation phase, operation phase and post-closure phase; - for three different rocks types: crystalline, argillaceous and tuff; - with specific focus on the issues of: Excavation Damaged Zone (EDZ), permanent property changes of rock masses, and glaciation and permafrost phenomena. The project involves a large number of research teams supported by radioactive waste management agencies or governmental regulatory bodies in Canada, China, Finland, France, Germany, Japan, Sweden and USA, who conducted advanced studies and numerical modelling of coupled THMC processes under five tasks. This report presents the definition of the first phase, Task A-1, of the Task A of the project. The task is a working example of how interaction between THMC modelling and SA analysis could be performed. Starting with the technical definition of the Task A, the report presents the results of preliminary THM calculations with a purpose of an initial appreciation of the phenomena and material properties that must be better understood in subsequent phases. Many simplifications and assumptions were introduced and the results should be considered under these assumptions. Based on the evaluation of the multiple teams' results, a few points of concern were identified that may guide the successive phases of Task A studies: 1. The predicted maximum total stress in the MX-80 bentonite could slightly exceed the 15 MPa design pressure for the

  8. Heterodyne Near-Field Scattering

    CERN Document Server

    Brogioli, D; Giglio, M; Giglio, Marzio

    2002-01-01

    We describe an optical technique based on the statistical analysis of the random intensity distribution due to the interference of the near-field scattered light with the strong transmitted beam. It is shown that, from the study of the two-dimensional power spectrum of the intensity, one derives the scattered intensity as a function of the scattering wave vector. Near-field conditions are specified and discussed. The substantial advantages over traditional scattering technique are pointed out, and is indicated that the technique could be of interest for wave lengths other than visible light.

  9. Tearing mode stability calculations with pressure flattening

    CERN Document Server

    Ham, C J; Cowley, S C; Hastie, R J; Hender, T C; Liu, Y Q

    2013-01-01

    Calculations of tearing mode stability in tokamaks split conveniently into an external region, where marginally stable ideal MHD is applicable, and a resonant layer around the rational surface where sophisticated kinetic physics is needed. These two regions are coupled by the stability parameter. Pressure and current perturbations localized around the rational surface alter the stability of tearing modes. Equations governing the changes in the external solution and - are derived for arbitrary perturbations in axisymmetric toroidal geometry. The relationship of - with and without pressure flattening is obtained analytically for four pressure flattening functions. Resistive MHD codes do not contain the appropriate layer physics and therefore cannot predict stability directly. They can, however, be used to calculate -. Existing methods (Ham et al. 2012 Plasma Phys. Control. Fusion 54 025009) for extracting - from resistive codes are unsatisfactory when there is a finite pressure gradient at the rational surface ...

  10. Pressure Profile Calculation with Mesh Ewald Methods.

    Science.gov (United States)

    Sega, Marcello; Fábián, Balázs; Jedlovszky, Pál

    2016-09-13

    The importance of calculating pressure profiles across liquid interfaces is increasingly gaining recognition, and efficient methods for the calculation of long-range contributions are fundamental in addressing systems with a large number of charges. Here, we show how to compute the local pressure contribution for mesh-based Ewald methods, retaining the typical N log N scaling as a function of the lattice nodes N. This is a considerable improvement on existing methods, which include approximating the electrostatic contribution using a large cutoff and the, much slower, Ewald calculation. As an application, we calculate the contribution to the pressure profile across the water/vapor interface, coming from different molecular layers, both including and removing the effect of thermal capillary waves. We compare the total pressure profile with the one obtained using the cutoff approximation for the calculation of the stresses, showing that the stress distributions obtained using the Harasima and Irving-Kirkwood path are quite similar and shifted with respect to each other at most 0.05 nm. PMID:27508458

  11. Pressure vessel calculations for VVER-440 reactors.

    Science.gov (United States)

    Hordósy, G; Hegyi, Gy; Keresztúri, A; Maráczy, Cs; Temesvári, E; Vértes, P; Zsolnay, E

    2005-01-01

    For the determination of the fast neutron load of the reactor pressure vessel a mixed calculational procedure was developed. The procedure was applied to the Unit II of Paks NPP, Hungary. The neutron source on the outer surfaces of the reactor was determined by a core design code, and the neutron transport calculations outside the core were performed by the Monte Carlo code MCNP. The reaction rate in the activation detectors at surveillance positions and at the cavity were calculated and compared with measurements. In most cases, fairly good agreement was found.

  12. Nanomanipulation using near field photonics.

    Science.gov (United States)

    Erickson, David; Serey, Xavier; Chen, Yih-Fan; Mandal, Sudeep

    2011-03-21

    In this article we review the use of near-field photonics for trapping, transport and handling of nanomaterials. While the advantages of traditional optical tweezing are well known at the microscale, direct application of these techniques to the handling of nanoscale materials has proven difficult due to unfavourable scaling of the fundamental physics. Recently a number of research groups have demonstrated how the evanescent fields surrounding photonic structures like photonic waveguides, optical resonators, and plasmonic nanoparticles can be used to greatly enhance optical forces. Here, we introduce some of the most common implementations of these techniques, focusing on those which have relevance to microfluidic or optofluidic applications. Since the field is still relatively nascent, we spend much of the article laying out the fundamental and practical advantages that near field optical manipulation offers over both traditional optical tweezing and other particle handling techniques. In addition we highlight three application areas where these techniques namely could be of interest to the lab-on-a-chip community, namely: single molecule analysis, nanoassembly, and optical chromatography.

  13. Near-field acoustical holography of military jet aircraft noise

    Science.gov (United States)

    Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

    2010-10-01

    Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

  14. Heterodyne method of apertureless near-field scanning optical microscopy on periodic gold nanowells.

    Energy Technology Data Exchange (ETDEWEB)

    Hall, J. E.; Wiederrecht, G. P.; Gray, S. K.; Chang, S.-H.; Jeon, S.; Rogers, J. A.; Bachelot, R.; Royer, P.; Univ. of Illinois; Univ. of Technology at Troyes; Inst. of Electro-Optical Science and Engineering

    2007-04-02

    Heterodyne detection for apertureless near-field scanning optical microscopy was used to study periodic gold nanowell arrays. Optical near-field amplitude and phase signals were obtained simultaneously with the topography of the gold nanowells and with different polarizations. Theoretical calculations of the near-fields were consistent with the experiments; in particular, the calculated amplitudes were in especially good agreement. The heterodyne method is shown to be particularly effective for these types of periodic photonic structures and other highly scattering media, which can overwhelm the near-field scattered signal when conventional apertureless near-field scanning optical microscopy is used.

  15. Pressure Vessel Calculations for VVER-440 Reactors

    Science.gov (United States)

    Hordósy, G.; Hegyi, Gy.; Keresztúri, A.; Maráczy, Cs.; Temesvári, E.; Vértes, P.; Zsolnay, É.

    2003-06-01

    Monte Carlo calculations were performed for a selected cycle of the Paks NPP Unit II to test a computational model. In the model the source term was calculated by the core design code KARATE and the neutron transport calculations were performed by the MCNP. Different forms of the source specification were examined. The calculated results were compared with measurements and in most cases fairly good agreement was found.

  16. Near Field Communication: Introduction and Implications

    Science.gov (United States)

    McHugh, Sheli; Yarmey, Kristen

    2012-01-01

    Near field communication is an emerging technology that allows objects, such as mobile phones, computers, tags, or posters, to exchange information wirelessly across a small distance. Though primarily associated with mobile payment, near field communication has many different potential commercial applications, ranging from marketing to nutrition,…

  17. Dynamic calculations of pressurized water reactor internals

    International Nuclear Information System (INIS)

    A mathematical model is briefly described for the calculation of oscillations in the WWER-440 reactor internals. The model was developed for improved safety of the type of reactors. It allows calculating vibrations resistance of reactor components, mainly during accidents, such as loss of coolant accidents. Some results are given of the calculation of forces acting in the rupture of the reactor inlet and outlet pipes. (Z.M.)

  18. Spherical wave rotation in spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Wu, Jian; Larsen, Flemming Holm; Lemanczyk, J.

    1991-01-01

    The rotation of spherical waves in spherical near-field antenna measurement is discussed. Considering the many difficult but interesting features of the rotation coefficients, an efficient rotation scheme is derived. The main feature of the proposed scheme is to ignore the calculation of the very...

  19. Attosecond nanoscale near-field sampling

    Science.gov (United States)

    Förg, B.; Schötz, J.; Süßmann, F.; Förster, M.; Krüger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; Pervak, V.; Kessel, A.; Trushin, S. A.; Azzeer, A. M.; Stockman, M. I.; Kim, D.; Krausz, F.; Hommelhoff, P.; Kling, M. F.

    2016-01-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted. PMID:27241851

  20. Infrared spectroscopic near-field mapping of single nanotransistors.

    Science.gov (United States)

    Huber, A J; Wittborn, J; Hillenbrand, R

    2010-06-11

    We demonstrate the application of scattering-type scanning near-field optical microscopy (s-SNOM) for infrared (IR) spectroscopic material recognition in state-of-the-art semiconductor devices. In particular, we employ s-SNOM for imaging of industrial CMOS transistors with a resolution better than 20 nm, which allows for the first time IR spectroscopic recognition of amorphous SiO(2) and Si(3)N(4) components in a single transistor device. The experimentally recorded near-field spectral signature of amorphous SiO(2) shows excellent agreement with model calculations based on literature dielectric values, verifying that the characteristic near-field contrasts of SiO(2) stem from a phonon-polariton resonant near-field interaction between the probing tip and the SiO(2) nanostructures. Local material recognition by s-SNOM in combination with its capabilities of contact-free and non-invasive conductivity- and strain-mapping makes IR near-field microscopy a versatile metrology technique for nanoscale material characterization and semiconductor device analysis with application potential in research and development, failure analysis and reverse engineering. PMID:20463381

  1. Infrared spectroscopic near-field mapping of single nanotransistors

    Energy Technology Data Exchange (ETDEWEB)

    Huber, A J; Hillenbrand, R [Nanooptics Group, CIC nanoGUNE Consolider, E-20018 Donostia, San Sebastian (Spain); Wittborn, J, E-mail: r.hillenbrand@nanogune.eu [Infineon Technologies AG, D-81739 Muenchen (Germany)

    2010-06-11

    We demonstrate the application of scattering-type scanning near-field optical microscopy (s-SNOM) for infrared (IR) spectroscopic material recognition in state-of-the-art semiconductor devices. In particular, we employ s-SNOM for imaging of industrial CMOS transistors with a resolution better than 20 nm, which allows for the first time IR spectroscopic recognition of amorphous SiO{sub 2} and Si{sub 3}N{sub 4} components in a single transistor device. The experimentally recorded near-field spectral signature of amorphous SiO{sub 2} shows excellent agreement with model calculations based on literature dielectric values, verifying that the characteristic near-field contrasts of SiO{sub 2} stem from a phonon-polariton resonant near-field interaction between the probing tip and the SiO{sub 2} nanostructures. Local material recognition by s-SNOM in combination with its capabilities of contact-free and non-invasive conductivity- and strain-mapping makes IR near-field microscopy a versatile metrology technique for nanoscale material characterization and semiconductor device analysis with application potential in research and development, failure analysis and reverse engineering.

  2. Numerical analysis of the temperature dependence of near-field polarization for nanoscale thermometry using a triple-tapered near-field optical fiber probe

    International Nuclear Information System (INIS)

    A novel nanoscale temperature measurement method using near-field polarization, namely polarized near-field optics thermal nanoscopy (P-NOTN), has been developed. This method is performed in illumination–collection mode (I–C mode) using an Au-coated near-field fiber probe, and enables non-contact and nanoscale temperature measurement. The polarization change of the near-field light due to temperature change in the I–C mode is complicated. In order to confirm and understand the temperature dependence of the near-field polarization, and assess the validity of the temperature measurement by P-NOTN, numerical investigations were performed by the finite-difference time-domain (FDTD) method, which numerically solves Maxwell’s equations. Three-dimensional models of the Au-coated near-field fiber probe and the one-dimensional nanostructure as a sample (i.e. Au nanorod) were produced. The electromagnetic field between the probe tip and the nanoscale sample was calculated by the FDTD method in order to evaluate the polarization change in the I–C mode. The calculation results showed that the polarization plane in the near field changes as a function of the refractive index of the sample, which in turn is temperature-dependent. These calculation results verified the capability of P-NOTN to achieve nanoscale temperature measurement by detecting the temperature-dependent polarization rotation change in the near field. (paper)

  3. Methodological problems in pressure profile calculations for lipid bilayers

    DEFF Research Database (Denmark)

    Sonne, Jacob; Hansen, Flemming Yssing; Peters, Günther H.J.

    2005-01-01

    From molecular dynamics simulations of a dipalmitoyl-phosphatidyl-choline (DPPC) lipid bilayer in the liquid crystalline phase, pressure profiles through the bilayer are calculated by different methods. These profiles allow us to address two central and unresolved problems in pressure profile...... calculations: The first problem is that the pressure profile is not uniquely defined since the expression for the local pressure involves an arbitrary choice of an integration contour. We have investigated two different choices leading to the Irving-Kirkwood (IK) and Harasima (H) expressions for the local...... pressure tensor. For these choices we find that the pressure profile is almost independent of the contour used, which indicates that the local pressure is well defined for a DPPC bilayer in the liquid crystalline phase. This may not be the case for other systems and we therefore suggest that both the IK...

  4. Measurements of near-field blast effects using kinetic plates

    International Nuclear Information System (INIS)

    Few tests have been designed to measure the near-field blast impulse of ideal and non-ideal explosives, mostly because of the inherent experimental difficulties due to non-transparent fireballs and thermal effects on gauges. In order to measure blast impulse in the near-field, a new test has been developed by firing spherical charges at 152 mm (6 in) from steel plates and probing acceleration using laser velocimetry. Tests measure the velocity imparted to the steel plate in the 50 – 300 μs timeframe, and are compared with free-field overpressure measurements at 1.52 m (5 ft) and ms timescales using piezoelectric pencil gauges. Specifically, tests have been performed with C4 to probe the contributions of ideal explosives and charge size effects. Non-ideal aluminized explosive formulations have been studied to explore the role of aluminum in near-field blast effects and far-field pressure, and are compared with formulations using LiF as an inert surrogate replacement for Al. The results are compared with other near-field blast tests and cylinder tests, and the validity of this test is explored with modeling and basic theory.

  5. Near-field diffraction of chirped gratings.

    Science.gov (United States)

    Sanchez-Brea, Luis Miguel; Torcal-Milla, Francisco Jose; Morlanes, Tomas

    2016-09-01

    In this Letter, we analyze the near-field diffraction pattern produced by chirped gratings. An intuitive analytical interpretation of the generated diffraction orders is proposed. Several interesting properties of the near-field diffraction pattern can be determined, such as the period of the fringes and its visibility. Diffraction orders present different widths and also, some of them present focusing properties. The width, location, and depth of focus of the converging diffraction orders are also determined. The analytical expressions are compared to numerical simulation and experimental results, showing a high agreement. PMID:27607980

  6. Near-Field Enhanced Negative Luminescent Refrigeration

    Science.gov (United States)

    Chen, Kaifeng; Santhanam, Parthiban; Fan, Shanhui

    2016-08-01

    We consider a near-field enhanced negative luminescent refrigeration system made of a polar material supporting surface-phonon polariton resonances and a narrow-band-gap semiconductor under a reverse bias. We show that in the near-field regime, such a device yields significant cooling power density and a high efficiency close to the Carnot limit. In addition, the performance of our system still persists even in the presence of strong nonidealities such as Auger recombination and sub-band-gap thermal radiation from free carriers.

  7. Attosecond nanoscale near-field sampling

    CERN Document Server

    Förg, Benjamin; Suessmann, Frederik; Foerster, Michael; Krueger, Michael; Ahn, Byung-Nam; Wintersperger, Karen; Zherebtsov, Sergey; Guggenmos, Alexander; Pervak, Vladimir; Kessel, Alexander; Trushin, Sergei; Azzeer, Abdallah; Stockman, Mark; Kim, Dong-Eon; Krausz, Ferenc; Hommelhoff, Peter; Kling, Matthias

    2015-01-01

    The promise of ultrafast light field driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical nearfields from light interaction with nanostructures with sub cycle resolution. Here, we experimentally demonstrate attosecond nearfield retrieval with a gold nanotip using streaking spectroscopy. By comparison of the results from gold nanotips to those obtained for a noble gas, the spectral response of the nanotip near field arising from laser excitation can be extracted. Monte Carlo MC trajectory simulations in near fields obtained with the macroscopic Maxwells equations elucidate the streaking mechanism on the nanoscale.

  8. Radiative heat transfer in the extreme near field.

    Science.gov (United States)

    Kim, Kyeongtae; Song, Bai; Fernández-Hurtado, Víctor; Lee, Woochul; Jeong, Wonho; Cui, Longji; Thompson, Dakotah; Feist, Johannes; Reid, M T Homer; García-Vidal, Francisco J; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2015-12-17

    Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer.

  9. Near-field/altered-zone models report

    Energy Technology Data Exchange (ETDEWEB)

    Hardin, E. L., LLNL

    1998-03-01

    nonlithophysal and lower lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF

  10. Near-field/altered-zone models report

    International Nuclear Information System (INIS)

    lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF/AZ performance. The selection and

  11. Near-field/altered-zone models report

    Energy Technology Data Exchange (ETDEWEB)

    Hardin, E. L., LLNL

    1998-03-01

    nonlithophysal and lower lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF

  12. Analytical stress tensor and pressure calculations with the CRYSTAL code

    OpenAIRE

    Doll, Klaus

    2010-01-01

    Abstract The calculation of the stress tensor and related properties and its implementation in the CRYSTAL code are described. The stress tensor is obtained from the earlier implemented analytical gradients with respect to the cell parameters. Subsequently, the pressure and enthalpy is computed, and a test concerning the pressure driven phase transition in KI is used as an illustration. Finally, the possibility of applying external pressure is implemented. The ...

  13. Computational lens for the near field

    DEFF Research Database (Denmark)

    Carney, P. Scott; Franzin, Richard A.; Bozhevolnyi, Sergey I.;

    2004-01-01

    A method is presented to reconstruct the structure of a scattering object from data acquired with a photon scanning tunneling microscope . The data may be understood to form a Gabor type near-field hologram and are obtained at a distance from the sample where the field is defocused and normally...

  14. Antenna Near-Field Probe Station Scanner

    Science.gov (United States)

    Zaman, Afroz J. (Inventor); Lee, Richard Q. (Inventor); Darby, William G. (Inventor); Barr, Philip J. (Inventor); Lambert, Kevin M (Inventor); Miranda, Felix A. (Inventor)

    2011-01-01

    A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described.

  15. Global Approach for Calculation of Minimum Miscibility Pressure

    DEFF Research Database (Denmark)

    Jessen, Kristian; Michelsen, Michael Locht; Stenby, Erling Halfdan

    1998-01-01

    An algorithm has been developed for calculation of minimum miscibility pressure (MMP) for the displacement of oil by multicomponent gas injection. The algorithm is based on the key tie line identification approach initially addressed by Wang and Orr [Y. Wang and F.M. Orr Jr., Analytical calculation...... of minimum miscibility pressure, Fluid Phase Equilibria, 139 (1997) 101-124]. In this work a new global approach is introduced. A number of deficiencies of the sequential approach have been eliminated resulting in a robust and highly efficient algorithm. The time consumption for calculation of the MMP...

  16. Impeller response calculation due to complex pressure loading

    Science.gov (United States)

    Wellstein, Carl

    1990-01-01

    An analysis technique is described to calculate the harmonic response of the first-stage impeller of the Space Shuttle Main Engine high pressure fuel turbopump. The excitation is a complex pressure loading at various locations on the impeller blades. The pressure loading was predicted using computational fluid dynamic techniques and was given as a Fourier series at 48 different locations on each of the three impeller blade types. The analysis consisted of mapping the pressures onto a three-dimensional finite element model, then converting these pressure loads to complex nodal force vectors at specified equal time intervals. The resulting vectors were then converted to modal force time histories that were then transformed into the frequency domain where the frequency response was calculated directly. This technique resulted in an improvement to the previously used direct integration technique and in a substantial analysis cost reduction.

  17. Near-field mapping by laser ablation of PMMA coatings

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana;

    The optical near-field of lithography-defined gold nanostructures, arranged into regular arrays on a gold film, is characterized via ablation of a polymer coating by laser illumination. The method utilizes femto-second laser pulses from a laser scanning microscope which induces electrical field...... enhancements on and around the gold nanostructures. At the positions of the enhancements, the ablation threshold of the polymer coating is significantly lowered creating sub-diffractional topographic modifications on the surface which are quantified via scanning electron microscopy and atomic force microscopy....... The obtained experimental results for different polymer coating thicknesses and nanostructure geometries are in good agreement with theoretical calculations of the near field distribution for corresponding enhancement mechanisms. The developed method and its tunable experimental parameters show that...

  18. Near-field effects of asteroid impacts in deep water

    Energy Technology Data Exchange (ETDEWEB)

    Gisler, Galen R [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Gittings, Michael L [Los Alamos National Laboratory

    2009-06-11

    Our previous work has shown that ocean impacts of asteroids below 500 m in diameter do not produce devastating long-distance tsunamis. Nevertheless, a significant portion of the ocean lies close enough to land that near-field effects may prove to be the greatest danger from asteroid impacts in the ocean. Crown splashes and central jets that rise up many kilometres into the atmosphere can produce, upon their collapse, highly non-linear breaking waves that could devastate shorelines within a hundred kilometres of the impact site. We present illustrative calculations, in two and three dimensions, of such impacts for a range of asteroid sizes and impact angles. We find that, as for land impacts, the greatest dangers from oceanic impacts are the short-term near-field, and long-term atmospheric effects.

  19. Near-field thermal electromagnetic transport

    CERN Document Server

    Edalatpour, Sheila

    2015-01-01

    A general near-field thermal electromagnetic transport formalism that is independent of the size, shape and number of heat sources is derived. The formalism is based on fluctuational electrodynamics, where fluctuating currents due to thermal agitation are added into Maxwell's curl equations, and is thus valid for heat sources in local thermodynamic equilibrium. Using a volume integral formulation, it is shown that the proposed formalism is a generalization of the classical electromagnetic scattering framework in which thermal emission is implicitly assumed to be negligible. The near-field thermal electromagnetic transport formalism is afterwards applied to a problem involving three spheres exchanging thermal radiation, where all multipolar interactions are taken into account. Using the thermal discrete dipole approximation, it is shown that depending on the dielectric function, the presence of a third sphere slightly affects the spatial distribution of power absorbed compared to the two-sphere case. The forma...

  20. Review of near-field optical microscopy

    Institute of Scientific and Technical Information of China (English)

    WU Shi-fa

    2006-01-01

    This review has introduced a new near-field optical microscope (NOM)-atomic force microscope combined with photon scanning tunneling microscope (AF/PSTM).During scanning,AF/PSTM could get two optical images of refractive index image and transmissivity image,and two AFM images of topography image and phase image.A reflected near-field optical microscope (AF/RSNOM) has also been developed on AF/PSTM platform.The NOM has been reviewed in this paper and the comparison between AF/PSTM & RSNOM and the commercial A-SNOM & RNOM has also been discussed.The functions of AF/PSTM & RSNOM are much better than A-SNOM & RNOM.

  1. Development of the near field geochemistry model

    International Nuclear Information System (INIS)

    This report discusses in a quantitative manner the evolution of the near field geochemistry as a result of the interactions between two different introducing granitic groundwaters and the FEBEX bentonite as a buffer material. The two granitic groundwaters considered are: SR-5 water, sampled in a borehole at 500 m depth in Mina Ratones, and a mean composition of different granitic groundwaters from the iberian Massif. The steel canister has also been introduced by considering the iron corrosion in anoxic conditions. (Author)

  2. THz Near-Field Microscopy and Spectroscopy

    OpenAIRE

    von Ribbeck, Hans-Georg

    2015-01-01

    Imaging with THz radiation at nanoscale resolution is highly desirable for specific material investigations that cannot be obtained in other parts of the electromagnetic spectrum. Nevertheless, classical free-space focusing of THz waves is limited to a >100 μm spatial resolution, due to the diffraction limit. However, the scattering- type scanning near-field optical microscopy (s-SNOM) promises to break this diffraction barrier. In this work, the realization of s-SNOM and spectroscopy for the...

  3. Evaluation of near-field earthquake effects

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, H.P.

    1994-11-01

    Structures and equipment, which are qualified for the design basis earthquake (DBE) and have anchorage designed for the DBE loading, do not require an evaluation of the near-field earthquake (NFE) effects. However, safety class 1 acceleration sensitive equipment such as electrical relays must be evaluated for both NFE and DBE since they are known to malfunction when excited by high frequency seismic motions.

  4. Near-field chemistry of the spent nuclear fuel repository

    International Nuclear Information System (INIS)

    Factors affecting near-field chemistry of the spent nuclear fuel repository as well as the involved mutual interactions are described on the basis of literature. The most important processes in the near-field (spent-fuel, canister and bentonite) are presented. The related examples on near-field chemistry models shed light on the extensive problematics of near-field chemistry. (authors)

  5. Wind turbine sound pressure level calculations at dwellings.

    Science.gov (United States)

    Keith, Stephen E; Feder, Katya; Voicescu, Sonia A; Soukhovtsev, Victor; Denning, Allison; Tsang, Jason; Broner, Norm; Leroux, Tony; Richarz, Werner; van den Berg, Frits

    2016-03-01

    This paper provides calculations of outdoor sound pressure levels (SPLs) at dwellings for 10 wind turbine models, to support Health Canada's Community Noise and Health Study. Manufacturer supplied and measured wind turbine sound power levels were used to calculate outdoor SPL at 1238 dwellings using ISO [(1996). ISO 9613-2-Acoustics] and a Swedish noise propagation method. Both methods yielded statistically equivalent results. The A- and C-weighted results were highly correlated over the 1238 dwellings (Pearson's linear correlation coefficient r > 0.8). Calculated wind turbine SPLs were compared to ambient SPLs from other sources, estimated using guidance documents from the United States and Alberta, Canada. PMID:27036282

  6. Preliminary near-field environment report

    International Nuclear Information System (INIS)

    The United States Department of Energy (DOE) is investigating the suitability of Yucca Mountain as a potential site for the nation's first high-level nuclear waste repository. The site is located about 120 km northwest of Las Vegas, Nevada, in an area of uninhabited desert (Fig. 1). Lawrence Livermore National Laboratory (LLNL) is a Yucca Mountain Site Characterization Project (YMP) participant and is responsible for the development of waste package (WP) and engineered barrier system (EBS) design concepts, including materials testing and selection, design criteria development, waste-form characterization, performance assessments, and near-field environment (NFE) characterization

  7. Scanning tip microwave near field microscope

    Science.gov (United States)

    Xiang, Xiao-Dong; Schultz, Peter G.; Wei, Tao

    1998-01-01

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an endwall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity.

  8. Near field of corrugated horns and its influence on dual reflector antenna radiation performance

    Science.gov (United States)

    Hombach, V.; Kuehn, E.

    1985-05-01

    The existing procedures for calculating the near field of the corrugated horns of dual reflector antennas are briefly reviewed, and their disadvantages are pointed out. A new approach to calculating the near field of circular corrugated feed horns is then discussed with specific reference to a Ku-band offset Gregorian antenna developed for the German Telecommunication Satellite DFS scheduled for launch in 1987. The approach, which is based on a physical-optics solution, is shown to provide an accurate description of the actual radiation characteristics. The effect of the near field on the gain, side-lobe level, and cross-polar performance of the antenna is discussed.

  9. Calculations of plastic collapse load of pressure vessel using FEA

    Institute of Scientific and Technical Information of China (English)

    Peng-fei LIU; Jin-yang ZHENG; Li MA; Cun-jian MIAO; Lin-lin WU

    2008-01-01

    This paper proposes a theoretical method using finite element analysis (FEA) to calculate the plastic collapse loads of pressure vessels under internal pressure, and compares the analytical methods according to three criteria stated in the ASME Boiler Pressure Vessel Code. First, a finite element technique using the arc-length algorithm and the restart analysis is developed to conduct the plastic collapse analysis of vessels, which includes the material and geometry non-linear properties of vessels. Second,as the mechanical properties of vessels are assumed to be elastic-perfectly plastic, the limit load analysis is performed by employing the Newton-Raphson algorithm, while the limit pressure of vessels is obtained by the twice-elastic-slope method and the tangent intersection method respectively to avoid excessive deformation. Finally, the elastic stress analysis under working pressure is conducted and the stress strength of vessels is checked by sorting the stress results. The results are compared with those obtained by experiments and other existing models. This work provides a reference for the selection of the failure criteria and the calculation of the plastic collapse load.

  10. Near Field Communication: Technology and Market Trends

    Directory of Open Access Journals (Sweden)

    Gabriella Arcese

    2014-09-01

    Full Text Available Among the different hi-tech content domains, the telecommunications industry is one of the most relevant, in particular for the Italian economy. Moreover, Near Field Communication (NFC represents an example of innovative production and a technological introduction in the telecommunications context. It has a threefold function: card emulator, peer-to-peer communication and digital content access, and it could be pervasively integrated in many different domains, especially in the mobile payment one. The increasing attention on NFC technology from the academic community has improved an analysis on the changes and the development perspective about mobile payments. It has considered the work done by the GSMA (Global System for Mobile Communications Association and the NFC Forum in recent years. This study starts from an analysis of the scientific contributions to Near Field Communication and how the main researches on this topic were conceived. Our focus is on the diffusion rates, the adoption rates and the technology life cycle. After that, we analyze the technical-economical elements of NFC. Finally, this work presents the state of art of the improvements to this technology with a deeper focus on NFC technologies applied to the tourism industry. In this way, we have done a case analysis that shows some of the NFC existent applications linked to each stage of the tourism value chain.

  11. Near Field Environment Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  12. Chemistry of the near field environment

    International Nuclear Information System (INIS)

    The chemistry of near field i.e. the pH, Eh and potential complexing ions, determines the solubility of radionuclides from a waste source. It is often assumed that outside the repository this chemistry is that of the appropriate groundwater. However, the chemical environment around the repository itself is perturbed both by the near field components, e.g. wasteform, backfill etc., and by the act of building the repository. Each of these components of the repository will establish chemical equilibrium with the aqueous phase in the interstices. The purpose of this programme is to establish to what extent the geological and chemical environment may be perturbed from its undisturbed state and at what distance from the repository the water chemistry is again controlled only by the geology of the far field. Two areas are used in predicting the overall chemical perturbations. These are 1.) experimental studies of clay to investigate the chemical composition and the buffering capacity against changes in pH and redox potential, and 2.) theoretical models which aim to study the evolution of the chemistry over longer time scales and assess the importance of individual chemical reactions to the overall behavior of the system. The behavior of the potential repository site over extended periods of time can only satisfactorily be predicted by a thoroughly validated mathematical model. This present exercise is one stage in the construction of such a model

  13. Magnetic dipole moment determination by near-field analysis

    Science.gov (United States)

    Eichhorn, W. L.

    1972-01-01

    A method for determining the magnetic moment of a spacecraft from magnetic field data taken in a limited region of space close to the spacecraft. The spacecraft's magnetic field equations are derived from first principles. With measurements of this field restricted to certain points in space, the near-field equations for the spacecraft are derived. These equations are solved for the dipole moment by a least squares procedure. A method by which one can estimate the magnitude of the error in the calculations is also presented. This technique was thoroughly tested on a computer. The test program is described and evaluated, and partial results are presented.

  14. PFLOW: A 3-D Numerical Modeling Tool for Calculating Fluid-Pressure Diffusion from Coulomb Strain

    Science.gov (United States)

    Wolf, L. W.; Lee, M.; Meir, A.; Dyer, G.; Ma, K.; Chan, C.

    2009-12-01

    A new 3D time-dependent pore-pressure diffusion model PFLOW is developed to investigate the response of pore fluids to the crustal deformation generated by strong earthquakes in heterogeneous geologic media. Given crustal strain generated by changes in Coulomb stress, this MATLAB-based code uses Skempton's coefficient to calculate resulting changes fluid pressure. Pore-pressure diffusion can be tracked over time in a user-defined model space with user-prescribed Neumann or Dirchilet boundary conditions and with spatially variable values of permeability. PFLOW employs linear or quadratic finite elements for spatial discretization and first order or second order, explicit or implicit finite difference discretization in time. PFLOW is easily interfaced with output from deformation modeling programs such as Coulomb (Toda et al., 2007) or 3D-DEF (Gomberg and Ellis, 1994). The code is useful for investigating to first-order the evolution of pore pressure changes induced by changes in Coulomb stress and their possible relation to water-level changes in wells or changes in stream discharge. It can also be used for student research and classroom instruction. As an example application, we calculate the coseismic pore pressure changes and diffusion induced by volumetric strain associated with the 1999 Chi-Chi earthquake (Mw = 7.6) in Taiwan. The Chi-Chi earthquake provides an unique opportunity to investigate the spatial and time-dependent poroelastic response of near-field rocks and sediments because there exist extensive observational data of water-level changes and crustal deformation. The integrated model allows us to explore whether changes in Coulomb stress can adequately explain hydrologic anomalies observed in areas such as Taiwan’s western foothills and the Choshui River alluvial plain. To calculate coseismic strain, we use the carefully calibrated finite fault-rupture model of Ma et al. (2005) and the deformation modeling code Coulomb 3.1 (Toda et al., 2007

  15. Near-Field Microscopy Studies of Lung Surfactant Collapse

    Science.gov (United States)

    Aga, Rachel; Dunn, Robert

    2003-03-01

    Respiratory distress syndrome (RDS), the fourth leading cause of infant mortality in the United States, arises from an insufficiently developed lung surfactant (LS). Healthy LS, a mixture of lipids and proteins that coats the inner surface of the lungs, reduces the alveolar surface tension to a few millinewtons per meter and, thus, facilitates breathing by stabilizing the large surface area changes associated with respiration. In the absence of an effective LS, surfactant collapse pressure (i.e., monolayer compressibility) and the ability of the monolayer to re-spread during the breathing cycle are reduced, resulting in labored breathing, reduced oxygen transport, and often death in those afflicted. In this study, we investigate the mechanism of collapse and re-spreading of a monolayer formed by a replacement surfactant commonly used in treatment of RDS. Through confocal microscopy fluorescence images obtained at a series of pressures near collapse, we find evidence for multilayer formation in the films. A further understanding of the collapse mechanism is obtained by comparing high resolution fluorescence and topography information measured with near-field scanning optical microscopy. The combined data from both confocal and near-field measurements are used to develop a model of lung surfactant collapse and re-spreading.

  16. Numerical Calculation on Cavitation Pressure Pulsation in Centrifugal Pump

    OpenAIRE

    Weidong Shi; Chuan Wang; Wei Wang; Bing Pei

    2014-01-01

    In order to study the internal flow in centrifugal pump when cavitation occurs, numerical calculation of the unsteady flow field in the WP7 automobile centrifugal pump is conducted based on the Navier-Stokes equations with the RNG k-ε turbulence model and Zwart-Gerber-Belamri cavitation model. The distributions of bubble volume fraction and pressure pulsation laws in the pump are analyzed when cavitation occurs. The conclusions are as follows: the bubble volume fraction is larger on the sucti...

  17. A subdivision algorithm for phase equilibrium calculations at high pressures

    Directory of Open Access Journals (Sweden)

    M. L. Corazza

    2007-12-01

    Full Text Available Phase equilibrium calculations at high pressures have been a continuous challenge for scientists and engineers. Traditionally, this task has been performed by solving a system of nonlinear algebraic equations originating from isofugacity equations. The reliability and accuracy of the solutions are strongly dependent on the initial guess, especially due to the fact that the phase equilibrium problems frequently have multiple roots. This work is focused on the application of a subdivision algorithm for thermodynamic calculations at high pressures. The subdivision algorithm consists in the application of successive subdivisions at a given initial interval (rectangle of variables and a systematic test to verify the existence of roots in each subinterval. If the interval checked passes in the test, then it is retained; otherwise it is discharged. The algorithm was applied for vapor-liquid, solid-fluid and solid-vapor-liquid equilibrium as well as for phase stability calculations for binary and multicomponent systems. The results show that the proposed algorithm was capable of finding all roots of all high-pressure thermodynamic problems investigated, independent of the initial guess used.

  18. A Study of a Powder Coating Gun near Field: A Case of Staggered Concentric Jet Flow

    Directory of Open Access Journals (Sweden)

    Edward Grandmaison

    2013-11-01

    Full Text Available This paper examines, experimentally and numerically, an isothermal coaxial air jet, created by an innovative nozzle design for an air propane torch, used for the thermal deposition of polymers. This design includes staggering the origins of the central and annular jets and creating an annular air jet with an inward radial velocity component. The experimental work used a Pitot tube to measure axial velocity on the jet centerline and in the fully developed flow. The static gauge pressure in the near field was also measured and found to be positive, an unexpected result. The numerical work used Gambit and Fluent. An extensive grid sensitivity study was conducted and it was found that results from a relatively coarse mesh were substantially the same as results from a mesh with almost 11 times the number of control volumes. A thorough evaluation of all of the RANS models in Fluent 6.3.26 found that the flow fields they calculated showed at most partial agreement with the experimental results. The greatest difference between numerical and experimental results was the incorrect prediction by all RANS models of a recirculation zone in the near field on the jet axis. Experimental work showed it did not exist.

  19. The role of pressure flattening in calculating tearing mode stability

    Science.gov (United States)

    Ham, C. J.; Connor, J. W.; Cowley, S. C.; Hastie, R. J.; Hender, T. C.; Liu, Y. Q.

    2013-12-01

    Calculations of tearing mode stability in tokamaks split conveniently into one in an external region, where marginally stable ideal magnetohydrodynamics (MHD) is applicable, and one in a resonant layer around the rational surface where sophisticated kinetic physics is needed. These two regions are coupled by the stability parameter Δ‧. Axisymmetric pressure and current perturbations localized around the rational surface significantly alter Δ‧. Equations governing the changes in the external solution and Δ‧ are derived for arbitrary perturbations in axisymmetric toroidal geometry. These equations can be used in two ways: (i) the Δ‧ can be calculated for a physically occurring perturbation to the pressure or current; (ii) alternatively we can use these equations to calculate Δ‧ for profiles with a pressure gradient at the rational surface in terms of the value when the perturbation removes this gradient. It is the second application we focus on here since resistive magnetohydrodynamics (MHD) codes do not contain the appropriate layer physics and therefore cannot predict stability for realistic hot plasma directly. They can, however, be used to calculate Δ‧. Existing methods (Ham et al 2012 Plasma Phys. Control. Fusion 54 025009) for extracting Δ‧ from resistive codes are unsatisfactory when there is a finite pressure gradient at the rational surface and favourable average curvature because of the Glasser stabilizing effect (Glasser et al 1975 Phys. Fluids 18 875). To overcome this difficulty we introduce a specific artificial pressure flattening function that allows the earlier approach to be used. The technique is first tested numerically in cylindrical geometry with an artificial favourable curvature. Its application to toroidal geometry is then demonstrated using the toroidal tokamak tearing mode stability code T7 (Fitzpatrick et al 1993 Nucl. Fusion 33 1533) which employs an approximate analytic equilibrium. The prospects for applying this

  20. The role of pressure flattening in calculating tearing mode stability

    International Nuclear Information System (INIS)

    Calculations of tearing mode stability in tokamaks split conveniently into one in an external region, where marginally stable ideal magnetohydrodynamics (MHD) is applicable, and one in a resonant layer around the rational surface where sophisticated kinetic physics is needed. These two regions are coupled by the stability parameter Δ′. Axisymmetric pressure and current perturbations localized around the rational surface significantly alter Δ′. Equations governing the changes in the external solution and Δ′ are derived for arbitrary perturbations in axisymmetric toroidal geometry. These equations can be used in two ways: (i) the Δ′ can be calculated for a physically occurring perturbation to the pressure or current; (ii) alternatively we can use these equations to calculate Δ′ for profiles with a pressure gradient at the rational surface in terms of the value when the perturbation removes this gradient. It is the second application we focus on here since resistive magnetohydrodynamics (MHD) codes do not contain the appropriate layer physics and therefore cannot predict stability for realistic hot plasma directly. They can, however, be used to calculate Δ′. Existing methods (Ham et al 2012 Plasma Phys. Control. Fusion 54 025009) for extracting Δ′ from resistive codes are unsatisfactory when there is a finite pressure gradient at the rational surface and favourable average curvature because of the Glasser stabilizing effect (Glasser et al 1975 Phys. Fluids 18 875). To overcome this difficulty we introduce a specific artificial pressure flattening function that allows the earlier approach to be used. The technique is first tested numerically in cylindrical geometry with an artificial favourable curvature. Its application to toroidal geometry is then demonstrated using the toroidal tokamak tearing mode stability code T7 (Fitzpatrick et al 1993 Nucl. Fusion 33 1533) which employs an approximate analytic equilibrium. The prospects for applying this

  1. Resolution of Internal Total Reflection Scanning Near-field Optical Microscopy

    Institute of Scientific and Technical Information of China (English)

    GE Huayong; GUO Qizhi; TAN Weihan

    2002-01-01

    In this paper, the probe-sample interaction equation based on Mie′s scattering theory is derived, and the resolution of scanning near field optical microscopy is calculated numerically. The results show that the offset of far-field component to near-field component in total field plays an important role in the resolution and the size of samples also has influence on resolution.

  2. The Survey on Near Field Communication

    Directory of Open Access Journals (Sweden)

    Vedat Coskun

    2015-06-01

    Full Text Available Near Field Communication (NFC is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem.

  3. Uncertainty analysis of two-phase flow pressure drop calculations

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, Cezar A.M.; Costa, Bruno M.P.; Fonseca Junior, Roberto da; Gonalves, Marcelo de A.L. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    The simulation of multiphase flow in pipes is usually performed by petroleum engineers with two main purposes: design of new pipelines and production systems; diagnosis of flow assurance problems in existing systems. The tools used for this calculation are computer codes that use published pressure drop correlations developed for steady-state two-phase flow, such as Hagedorn-Brown, Beggs and Brill and others. Each one of these correlations is best suited for a given situation and the engineer must find out the best option for each particular case, based on his experience. In order to select the best correlation to use and to analyze the results of the calculation, the engineer must determine the reliability of computed values. The uncertainty of the computation is obtained by considering uncertainties of the correlation adopted, of the calculation algorithm and the input data. This paper proposes a method to evaluate the uncertainties of this type of calculation and presents an analysis of these uncertainties. The uncertainty analysis also allows the identification of the parameters that are more significant for the final uncertainty of the simulation. Therefore it makes possible to determine which are the input parameters that must be determined with higher accuracy and the ones that may have lower accuracy, without reducing the reliability of the results. (author)

  4. Assessment of Near-Field Sonic Boom Simulation Tools

    Science.gov (United States)

    Casper, J. H.; Cliff, S. E.; Thomas, S. D.; Park, M. A.; McMullen, M. S.; Melton, J. E.; Durston, D. A.

    2008-01-01

    A recent study for the Supersonics Project, within the National Aeronautics and Space Administration, has been conducted to assess current in-house capabilities for the prediction of near-field sonic boom. Such capabilities are required to simulate the highly nonlinear flow near an aircraft, wherein a sonic-boom signature is generated. There are many available computational fluid dynamics codes that could be used to provide the near-field flow for a sonic boom calculation. However, such codes have typically been developed for applications involving aerodynamic configuration, for which an efficiently generated computational mesh is usually not optimum for a sonic boom prediction. Preliminary guidelines are suggested to characterize a state-of-the-art sonic boom prediction methodology. The available simulation tools that are best suited to incorporate into that methodology are identified; preliminary test cases are presented in support of the selection. During this phase of process definition and tool selection, parallel research was conducted in an attempt to establish criteria that link the properties of a computational mesh to the accuracy of a sonic boom prediction. Such properties include sufficient grid density near shocks and within the zone of influence, which are achieved by adaptation and mesh refinement strategies. Prediction accuracy is validated by comparison with wind tunnel data.

  5. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Stephen J.; Ni, Guangjian [Institute of Sound and Vibration Research, University of Southampton, Southampton (United Kingdom)

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  6. Signal of microstrip scanning near-field optical microscope in far- and near-field zones.

    Science.gov (United States)

    Morozov, Yevhenii M; Lapchuk, Anatoliy S

    2016-05-01

    An analytical model of interference between an electromagnetic field of fundamental quasi-TM(EH)00-mode and an electromagnetic field of background radiation at the apex of a near-field probe based on an optical plasmon microstrip line (microstrip probe) has been proposed. The condition of the occurrence of electromagnetic energy reverse flux at the apex of the microstrip probe was obtained. It has been shown that the nature of the interference depends on the length of the probe. Numerical simulation of the sample scanning process was conducted in illumination-reflection and illumination-collection modes. Results of numerical simulation have shown that interference affects the scanning signal in both modes. However, in illumination-collection mode (pure near-field mode), the signal shape and its polarity are practically insensible to probe length change; only signal amplitude (contrast) is slightly changed. However, changing the probe length strongly affects the signal amplitude and shape in the illumination-reflection mode (the signal formed in the far-field zone). Thus, we can conclude that even small background radiation can significantly influence the signal in the far-field zone and has practically no influence on a pure near-field signal. PMID:27140358

  7. Theoretical and experimental examination of near-field acoustic levitation.

    Science.gov (United States)

    Nomura, Hideyuki; Kamakura, Tomoo; Matsuda, Kazuhisa

    2002-04-01

    A planar object can be levitated stably close to a piston sound source by making use of acoustic radiation pressure. This phenomenon is called near-field acoustic levitation [Y. Hashimoto et al., J. Acoust. Soc. Am. 100, 2057-2061 (1996)]. In the present article, the levitation distance is predicted theoretically by numerically solving basic equations in a compressible viscous fluid subject to the appropriate initial and boundary conditions. Additionally, experiments are carried out using a 19.5-kHz piston source with a 40-mm aperture and various aluminum disks of different sizes. The measured levitation distance agrees well with the theory, which is different from a conventional theory, and the levitation distance is not inversely proportional to the square root of the surface density of the levitated disk in a strict sense. PMID:12002842

  8. Near-field scanning microwave microscopy of microwave devices

    Science.gov (United States)

    Vlahacos, C. P.; Steinhauer, David E.; Dutta, S.; Anlage, S. M.; Wellstood, F. C.; Newman, H.

    1997-03-01

    We have developed a scanning microwave microscope which can presently image features with a spatial resolution of 10-100 μm in the frequency range 5-15 GHz.(C. P. Vlahacos, et al.), Appl. Phys. Lett. 69, 3272 (1996).^,(S. M. Anlage, et al.), IEEE. Trans. Appl. Supercond. (1997). The microscope consists of a resonant section of a coaxial cable which is terminated with a small-diameter open-ended coaxial probe. Images are made by scanning the sample under the probe while recording the induced near-field microwave voltage as a function of sample position. We will present images for several microwave devices, including an X-band microstrip planar ferrite circulator and a high-temperature superconducting microstrip YBa_2Cu_3O_7-δ resonator, and compare them to the calculated field profiles.

  9. Metrology of Electromagnetic Intensity Measurement in Near Field

    Directory of Open Access Journals (Sweden)

    Jozef Slížik

    2013-07-01

    Full Text Available This paper is dealing with measurement of a near-field strength in the region around a source, which is supply of radiation. Electromagnetic field is distributed inhomogeneously in this case. The field consists of two components field, vectors of electric and magnetic field. The intensity of the components of the electric field is calculated using the modified Maxwell equation. Also intensity is calculated by averaging the results of the Maxwell`s equations. The calculation of the components of the electric field intensity using two methods are different. The method of calculating electric field (averaging, which represents real measurement, is loaded by error. The real measurement is loaded by the averaging error, too. The paper is also dealing with problem of mentioned field components measurement using multiple sensors – electrical short dipoles. Impact of size of the electromagnetic field sensor on a measurement accuracy of individual components, such as impact on the resulting vector of the electrical field, is expressed in this paper. We achieve better results of joinder and less measurement uncertainty of electric field at the exercise of joinder units of the electric field in metrological laboratories

  10. Dielectric versus topographic contrast in near-field microscopy

    OpenAIRE

    Girard, C.; Dereux, A.; Martin, O. J. F.

    1996-01-01

    Using a fully vectorial three-dimensional numerical approach (generalized field propagator, based on Green's tensor technique), we investigate the near-field images produced by subwavelength objects buried in a dielectric surface. We study the influence of the object index, size, and depth on the near field. We emphasize the similarity between the near field spawned by an object buried in the surface (dielectric contrast) and that spawned by a protrusion on the surface (topographic contrast)....

  11. Near-Field Optical Microscopy of Fractal Structures

    DEFF Research Database (Denmark)

    Coello, Victor; Bozhevolnyi, Sergey I.

    1999-01-01

    Using a photon scanning tunnelling microscope combined with a shear-force feedback system, we image both topographical and near-field optical images (at the wavelengths of 633 and 594 nm) of silver colloid fractals. Near-field optical imaging is calibrated with a standing evanescent wave pattern....

  12. Ultrafast infrared near-field molecular nano-spectroscopy

    Directory of Open Access Journals (Sweden)

    Rang Matthias

    2013-03-01

    Full Text Available We demonstrate molecular radiative infrared vibrational free-induction decay on the nano-scale and its control via near-field coupling between the transient molecular polarization and optical antenna properties of the metallic scanning near-field probe tip. This allows for pushing the sensitivity of infrared vibrational spectroscopy into the single molecule regime.

  13. Heat flux splitter for near-field thermal radiation

    CERN Document Server

    Ben-Abdallah, Philippe; Frechette, Luc; Biehs, Svend-Age

    2015-01-01

    We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the developement of an active control of propagation directions for heat fluxes exchanged in near-field throughout integrated nanostructures networks.

  14. Heat flux splitter for near-field thermal radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Abdallah, P., E-mail: pba@institutoptique.fr [Laboratoire Charles Fabry, UMR 8501, Institut d' Optique, CNRS, Université Paris-Sud, 11, 2, Avenue Augustin Fresnel, 91127 Palaiseau Cedex (France); Belarouci, A.; Frechette, L. [Laboratoire Nanotechnologies Nanosystèmes (LN2)-CNRS UMI-3463, Université de Sherbrooke, 3000 Boulevard de l' Université, Sherbrooke, Québec J1 K 0A5 (Canada); Biehs, S.-A. [Institut für Physik, Carl von Ossietzky Universität, D-26111 Oldenburg (Germany)

    2015-08-03

    We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the development of an active control of propagation directions for heat fluxes exchanged in the near field throughout integrated nanostructured networks.

  15. Near field characteristics of buoyant helium plumes

    Indian Academy of Sciences (India)

    Kuchimanchi K Bharadwaj; Debopam Das; Pavan K Sharma

    2015-05-01

    Puffing and entrainment characteristics of helium plumes emanating out into ambient air from a circular orifice are investigated in the present study. Velocity and density fields are measured across a diametric plane using Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) respectively in phase resolved manner. Experiments are performed in Froude numbers range 0.2–0.4 and for Reynolds numbers 58–248. Puffing frequency measurements reveal that the plume puffing frequencies are insensitive to the plume exit conditions, since the instability is buoyancy driven. The frequencies obtained in the present case are in agreement with frequencies obtained by Cetegen & Kasper (1996) for plumes originating from circular nozzles of various L/D ratios. Velocity and density measurements reveal that toroidal vortex formed during a puffing cycle entrains ambient air as it traverses downstream and this periodic engulfment governs the entrainment mechanism in pulsating plumes. The obtained velocity and density fields are used to calculate mass entrainment rates. It is revealed that though the flow is unsteady, the contribution of unsteady term in mass conservation to entrainment is negligible, and it becomes zero over a puff cycle. Finally, an empirical relation for variation of mass entrainment with height has been proposed, in which the non-dimensional mass entrainment is found to follow a power law with the non-dimensional height.

  16. Near-field thermodynamics and nanoscale energy harvesting

    Science.gov (United States)

    Latella, Ivan; Pérez-Madrid, Agustín; Lapas, Luciano C.; Rubi, J. Miguel

    2015-10-01

    We study the thermodynamics of near-field thermal radiation between two identical polar media at different temperatures. As an application, we consider an idealized energy harvesting process from sources at near room temperature at the nanoscale. We compute the maximum work flux that can be extracted from the radiation in the near-field regime and compare it with the corresponding maximum work flux in the blackbody regime. This work flux is considerably higher in the near-field regime. For materials that support surface phonon polaritons, explicit expressions for the work flux and an upper bound for the efficiency as functions of the surface wave frequency are obtained.

  17. Transfer functions in collection scanning near-field optical microscopy

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Vohnsen, Brian; Bozhevolnaya, Elena A.

    1999-01-01

    It is generally accepted that, if in collection near-field optical microscopy the probe-sample coupling can be disregarded, a fiber probe can be considered as a detector of the near-field intensity whose size can be accounted for via an intensity transfer function. We show that, in general...... are considered with respect to the relation between near-field optical images and the corresponding intensity distributions. Our conclusions are supported with numerical simulations and experimental results obtained by using a photon scanning tunneling microscope with an uncoated fiber tip....

  18. Resolution of objects within subwavelength range by using the near field of a dipole

    CERN Document Server

    Kolkiran, Aziz

    2012-01-01

    We analyze the far field resolution of apertures which are illuminated by a point dipole located at subwavelength distances. It is well known that radiation emitted by a localized source can be considered a combination of travelling and evanescent waves, when represented by the angular spectrum method. The evanescent wave part of the source can be converted to propagating waves by diffraction at the aperture thereby it contributes to the far field detection. Therefore one can expect an increase in the resolution of objects. We present explicit calculations showing that the resolution at the far zone is improved by decreasing the source-aperture distance. We also utilize the resolution enhancement by the near field of a dipole to resolve two closely located apertures. The results show that without the near field (evanescent field) the apertures are not resolved whereas with the near field of the dipole the far zone intensity distribution shows improved resolution. This method eliminates the requirements of nea...

  19. Calculation of minimum miscibility pressure using fast slimtube simulation

    DEFF Research Database (Denmark)

    Yan, Wei; Michelsen, Michael Locht; Stenby, Erling Halfdan

    2012-01-01

    Minimum misciblility pressure (MMP) is a critical parameter in designing a miscible gas injection process. It is expected that 100% displacement efficiency on the microscopic scale can be achieved provided the injection pressure is above MMP. Two approaches are usually employed for equation...

  20. Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe

    Science.gov (United States)

    Fujii, T.; Taguchi, Y.; Saiki, T.; Nagasaka, Y.

    2012-12-01

    A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

  1. Near-field and far-field goniophotometry of focused LED arrays

    Science.gov (United States)

    Jacobs, Valéry A.; Forment, Stefaan; Rombauts, Patrick; Hanselaer, Peter

    2014-05-01

    Luminaires are conventionally modeled using a far-field representation. To calculate this representation, a photometer revolves a light source at fixed distance and illuminances are measured in a set of angular directions. Using the inversesquare- law, the far-field intensity, also termed luminous intensity distribution is then calculated. For Lambertian sources, the far-field starts from a distance of five times the maximal dimension of a light source; which is called the limiting photometric distance. The advent of luminaires composed of LED arrays with narrow beams have shown that this limit is no longer valid and far larger distances (up to 15 times the maximal diameter) are suggested by the lighting community. This problem is even more outspoken when the individual LEDs are focused at close distance, as in e.g. surgical luminaires. To overcome these problems, we exploit the use of a near-field representation to describe an array of two narrow-beam LEDs focused at close distance. For such a test source, this paper shows how a near-field luminance goniometer is able to construct ray-data. Ray files can be used to calculate a near-field representation and far-field representation of a light source. These measurements are validated by a theoretical derivation of the intensity of an array, using a simple analytical model to describe the emission of the individual LEDs. This near-field approach makes discussions to determine the far-field photometric distance superfluous.

  2. Integration and Evaluation of Nanophotonic Devices Using Optical Near Field

    Science.gov (United States)

    Yatsui, Takashi; Nomura, Wataru; Yi, Gyu-Chul; Ohtsu, Motoichi

    In this chapter, we review the optical near-field phenomena and their applications to realize the nanophotonic device. To realize the nanometer-scale controllability in size and position, we demonstrate the feasibility of nanometer-scale chemical vapor deposition using optical near-field techniques (see Sect. 15.2). In which, the probe-less fabrication method for mass production is also demonstrated. To confirm the promising optical properties of individual ZnO for realizing nanophotonic devices, we performed the near-field evaluation of the ZnO quantum structure (see Sect. 15.3). To drive the nanophotonic device with external conventional diffraction-limited photonic device, the far-/near-field conversion device is required. Section 15.4 reviews nanometer-scale waveguide to be used as such a conversion device of the nanophotonic ICs.

  3. Principles of planar near-field antenna measurements

    CERN Document Server

    Gregson, Stuart; Parini, Clive

    2007-01-01

    This single volume provides a comprehensive introduction and explanation of both the theory and practice of 'Planar Near-Field Antenna Measurement' from its basic postulates and assumptions, to the intricacies of its deployment in complex and demanding measurement scenarios.

  4. Near-Field Microwave Microscopy of Materials Properties

    OpenAIRE

    Anlage, Steven M.; Steinhauer, D. E.; Feenstra, B. J.; Vlahacos, C. P.; Wellstood, F. C.

    2000-01-01

    Near-field microwave microscopy has created the opportunity for a new class of electrodynamics experiments of materials. Freed from the constraints of traditional microwave optics, experiments can be carried out at high spatial resolution over a broad frequency range. In addition, the measurements can be done quantitatively so that images of microwave materials properties can be created. We review the five major types of near-field microwave microscopes and discuss our own form of microscopy ...

  5. Non-contact transportation using near-field acoustic levitation

    Science.gov (United States)

    Ueha; Hashimoto; Koike

    2000-03-01

    Near-field acoustic levitation, where planar objects 10 kg in weight can levitate stably near the vibrating plate, is successfully applied both to non-contact transportation of objects and to a non-contact ultrasonic motor. Transporting apparatuses and an ultrasonic motor have been fabricated and their characteristics measured. The theory of near-field acoustic levitation both for a piston-like sound source and a flexural vibration source is also briefly described. PMID:10829622

  6. Scanning near-field infrared microscopy on semiconductor structures

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Rainer

    2011-01-15

    Near-field optical microscopy has attracted remarkable attention, as it is the only technique that allows the investigation of local optical properties with a resolution far below the diffraction limit. Especially, the scattering-type near-field optical microscopy allows the nondestructive examination of surfaces without restrictions to the applicable wavelengths. However, its usability is limited by the availability of appropriate light sources. In the context of this work, this limit was overcome by the development of a scattering-type near-field microscope that uses a widely tunable free-electron laser as primary light source. In the theoretical part, it is shown that an optical near-field contrast can be expected when materials with different dielectric functions are combined. It is derived that these differences yield different scattering cross-sections for the coupled system of the probe and the sample. Those cross-sections define the strength of the near-field signal that can be measured for different materials. Hence, an optical contrast can be expected, when different scattering cross-sections are probed. This principle also applies to vertically stacked or even buried materials, as shown in this thesis experimentally for two sample systems. In the first example, the different dielectric functions were obtained by locally changing the carrier concentration in silicon by the implantation of boron. It is shown that the concentration of free charge-carriers can be deduced from the near-field contrast between implanted and pure silicon. For this purpose, two different experimental approaches were used, a non-interferometric one by using variable wavelengths and an interferometric one with a fixed wavelength. As those techniques yield complementary information, they can be used to quantitatively determine the effective carrier concentration. Both approaches yield consistent results for the carrier concentration, which excellently agrees with predictions from

  7. Scanning near-field infrared microscopy on semiconductor structures

    International Nuclear Information System (INIS)

    Near-field optical microscopy has attracted remarkable attention, as it is the only technique that allows the investigation of local optical properties with a resolution far below the diffraction limit. Especially, the scattering-type near-field optical microscopy allows the nondestructive examination of surfaces without restrictions to the applicable wavelengths. However, its usability is limited by the availability of appropriate light sources. In the context of this work, this limit was overcome by the development of a scattering-type near-field microscope that uses a widely tunable free-electron laser as primary light source. In the theoretical part, it is shown that an optical near-field contrast can be expected when materials with different dielectric functions are combined. It is derived that these differences yield different scattering cross-sections for the coupled system of the probe and the sample. Those cross-sections define the strength of the near-field signal that can be measured for different materials. Hence, an optical contrast can be expected, when different scattering cross-sections are probed. This principle also applies to vertically stacked or even buried materials, as shown in this thesis experimentally for two sample systems. In the first example, the different dielectric functions were obtained by locally changing the carrier concentration in silicon by the implantation of boron. It is shown that the concentration of free charge-carriers can be deduced from the near-field contrast between implanted and pure silicon. For this purpose, two different experimental approaches were used, a non-interferometric one by using variable wavelengths and an interferometric one with a fixed wavelength. As those techniques yield complementary information, they can be used to quantitatively determine the effective carrier concentration. Both approaches yield consistent results for the carrier concentration, which excellently agrees with predictions from

  8. Study on Transient Properties of Levitated Object in Near-Field Acoustic Levitation

    Science.gov (United States)

    Jia, Bing; Chen, Chao; Zhao, Chun-Sheng

    2011-12-01

    A new approach to the study on the transient properties of the levitated object in near-field acoustic levitation (NFAL) is presented. In this article, the transient response characteristics, including the levitated height of an object with radius of 24 mm and thickness of 5 mm, the radial velocity and pressure difference of gas at the boundary of clearance between the levitated object and radiating surface (squeeze film), is calculated according to several velocity amplitudes of radiating surface. First, the basic equations in fluid areas on Arbitrary Lagrange—Euler (ALE) form are numerically solved by using streamline upwind petrov galerkin (SUPG) finite elements method. Second, the formed algebraic equations and solid control equations are solved by using synchronous alternating method to gain the transient messages of the levitated object and gas in the squeeze film. Through theoretical and numerical analyses, it is found that there is a oscillation time in the transient process and that the response time does not simply increase with the increasing of velocity amplitudes of radiating surface. More investigations in this paper are helpful for the understanding of the transient properties of levitated object in NFAL, which are in favor of enhancing stabilities and responsiveness of levitated object.

  9. Study on Transient Properties of Levitated Object in Near-Field Acoustic Levitation

    Institute of Scientific and Technical Information of China (English)

    贾兵; 陈超; 赵淳生

    2011-01-01

    A new approach to the study on the transient properties of the levitated object in near-field acoustic levitation (NFAL) is presented. In this article, the transient response characteristics, including the levitated height of an object with radius of 24 mm and thickness of 5 mm, the radial velocity and pressure difference of gas at the boundary of clearance between the levitated object and radiating surface (squeeze film), is calculated according to severa/velocity amplitudes of radiating surface. First, the basic equations in fluid areas on Arbitrary Lagrange--Euler (ALE) form are numericaJly solved by using streamline upwind petrov gaJerkin (SUPG) finite elements method. Second, the formed a/gebraic equations and solid control equations are solved by using synchronous alternating method to gain the transient messages of the levitated object and gas in the squeeze film. Through theoretical and numerical analyses, it is found that there is a oscillation time in the transient process and that the response time does not simply increase with the increasing of velocity amplitudes of radiating surface. More investigations in this paper are helpful for the understanding of the transient properties of levitated object in NFAL, which are in favor of enhancing stabilities and responsiveness of levitated object.

  10. Spectrally enhancing near-field radiative heat transfer by exciting magnetic polariton in SiC gratings

    OpenAIRE

    Yang, Yue; Wang, Liping

    2015-01-01

    In the present work, we theoretically demonstrate, for the first time, that near field radiative transport between 1D periodic grating microstructures separated by subwavelength vacuum gaps can be significantly enhanced by exciting magnetic resonance or polariton. Fluctuational electrodynamics that incorporates scattering matrix theory with rigorous coupled wave analysis is employed to exactly calculate the near field radiative heat flux between two SiC gratings. Besides the well known couple...

  11. Modelling and closed loop control of near-field acoustically levitated objects

    CERN Document Server

    Ilssar, Dotan; Flashner, Henryk

    2016-01-01

    The present paper introduces a novel approach for modelling the governing, slow dynamics of near-field acoustically levitated objects. This model is sufficiently simple and concise to enable designing a closed-loop controller, capable of accurate vertical positioning of a carried object. The near-field acoustic levitation phenomenon exploits the compressibility, the nonlinearity and the viscosity of the gas trapped between a rapidly oscillating surface and a freely suspended planar object, to elevate its time averaged pressure above the ambient pressure. By these means, the vertical position of loads weighing up to several kilograms can be varied between dozens and hundreds of micrometers. The simplified model developed in this paper is a second order ordinary differential equation where the height-dependent stiffness and damping terms of the gas layer are derived explicitly. This simplified model replaces a traditional model consisting of the equation of motion of the levitated object, coupled to a nonlinear...

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

    CERN Document Server

    Pan, Zhao; 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.

  13. 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.

  14. THz near-field imaging of biological tissues employing synchrotronradiation

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried,Daniel

    2004-12-23

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking onto the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical wave guides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about lambda/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 mu-m at about 12 wave numbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

  15. Effects of a Near Field Pyroshock on the Performance of a Nitramine Nitrocellulose Propellant

    Science.gov (United States)

    Baca, Arcenio

    2016-01-01

    The purpose of this study is to investigate the effects of a pyroshock environment on the performance characteristics of a propellant used in pyrotechnic devices such as guillotine cutters. A heritage pressure cartridge assembly which uses a nitramine nitrocellulose propellant with a known performance baseline will be exposed to a near field pyroshock event. The pressure cartridge will then be fired in an ambient closed bomb firing to collect pressure time history. This data will be compared to the baseline data to evaluate the effects of the shock on the performance of the propellant.

  16. Effects of Near Field Pyroshock on the Performance of a Nitramine Nitrocellulose Propellant

    Science.gov (United States)

    Baca, Arcenio B.

    2016-01-01

    The overall purpose of this study is to investigate the effects of a pyroshock environment on the performance characteristics of a propellant used in pyrotechnic devices such as guillotine cutters. Near field pyroshock which is defined by acceleration amplitudes in excess of 10,000g at a frequency of greater than 10,000 Hz is a highly transient environment that has a known potential to cause failure in both structural and electronic components. A heritage pressure cartridge assembly which uses a nitramine nitrocellulose propellant with a known performance baseline will be exposed to a near field pyroshock event. The pressure cartridge will then be fired in an ambient closed bomb firing to collect pressure time history. The two performance characteristics that will be evaluated are the pressure amplitude and time to peak pressure. This data will be compared to the base-lined ambient closed bomb data to evaluate the effects of the shock on the performance of the propellant. It is expected that the pyroshock environment will cause brittle failures of the propellant increasing the surface area of said propellant. This increase of surface area should result in increased combustion rate which should show as an increased pressure peak and decreased time to peak pressure in the pressure time data.

  17. Near-field radiative thermal transport: From theory to experiment

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bai, E-mail: baisong@umich.edu; Fiorino, Anthony; Meyhofer, Edgar, E-mail: meyhofer@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Reddy, Pramod, E-mail: pramodr@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2015-05-15

    Radiative thermal transport via the fluctuating electromagnetic near-field has recently attracted increasing attention due to its fundamental importance and its impact on a range of applications from data storage to thermal management and energy conversion. After a brief historical account of radiative thermal transport, we summarize the basics of fluctuational electrodynamics, a theoretical framework for the study of radiative heat transfer in terms of thermally excited propagating and evanescent electromagnetic waves. Various approaches to modeling near-field thermal transport are briefly discussed, together with key results and proposals for manipulation and utilization of radiative heat flow. Subsequently, we review the experimental advances in the characterization of both near-field heat flow and energy density. We conclude with remarks on the opportunities and challenges for future explorations of radiative heat transfer at the nanoscale.

  18. Near-Field Cross Section Imaging of Wideband Millimeter Wave

    Directory of Open Access Journals (Sweden)

    Kan Yingzhi

    2016-01-01

    Full Text Available Near-field millimeter wave imaging has been a hot topic recent years for its importance applications in the area of anti-terrorism. The penetrating characteristic of millimeter wave is of significant importance to security, such as the concealed weapons detection, ground-penetrating radar imaging, through-barrier imaging and so on. Cross section imaging is a basic aspect for near-field millimeter wave imaging, which includes antenna array distribution and wideband signal processing. This paper utilizes back projection method in space area to realize ultra-band nearfield cross section imaging. We induce two dimensional direction integral formulas to obtain the reconstruction image of the near-field imaging area, and the simulation results validate the effectiveness of this imaging algorithm.

  19. Near-field second-harmonic generation from gold nanoellipsoids

    Energy Technology Data Exchange (ETDEWEB)

    Celebrano, M.; Zavelani-Rossi, M.; Polli, D.; Cerullo, G. [Istituto di Fotonica e Nanotecnologie, CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Biagioni, P.; Finazzi, M.; Duo, L. [LNESS - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Labardi, M.; Allegrini, M. [CNR-INFM, polyLab, Dipartimento di Fisica ' Enrico Fermi' , Universita di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Grand, J.; Adam, P.M.; Royer, P. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060 10010 Troyes cedex (France)

    2008-07-01

    Second-harmonic generation from single gold nanofabricated particles is experimentally investigated by a nonlinear scanning near-field optical microscope (SNOM). High peak power femtosecond polarized light pulses at the output of a hollow pyramid aperture allow for efficient second-harmonic imaging, with sub-100-nm spatial resolution and high contrast. The near-field nonlinear response is found to be directly related to both local surface plasmon resonances and particle morphology. The combined analysis of linear and second-harmonic SNOM images allows one to discriminate among near-field scattering, absorption and re-emission processes, which would not be possible with linear techniques alone. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Field of view for near-field aperture synthesis imaging

    CERN Document Server

    Buscher, David F

    2015-01-01

    Aperture synthesis techniques are increasingly being employed to provide high angular resolution images in situations where the object of interest is in the near field of the interferometric array. Previous work has showed that an aperture synthesis array can be refocused on an object in the near field of an array, provided that the object is smaller than the effective Fresnel zone size corresponding to the array-object range. We show here that, under paraxial conditions, standard interferometric techniques can be used to image objects which are substantially larger than this limit. We also note that interferometric self-calibration and phase-closure image reconstruction techniques can be used to achieve near-field refocussing without requiring accurate object range information. We use our results to show that the field of view for high-resolution aperture synthesis imaging of geosynchronous satellites from the ground can be considerably larger than the largest satellites in Earth orbit.

  1. Near-field energy extraction with hyperbolic metamaterials.

    Science.gov (United States)

    Shi, Jiawei; Liu, Baoan; Li, Pengfei; Ng, Li Yen; Shen, Sheng

    2015-02-11

    Although blackbody radiation described by Planck's law is commonly regarded as the maximum of thermal radiation, thermal energy transfer in the near-field can exceed the blackbody limit due to the contribution from evanescent waves. Here, we demonstrate experimentally a broadband thermal energy extraction device based on hyperbolic metamaterials that can significantly enhance near-field thermal energy transfer. The thermal extractor made from hyperbolic metamaterials does not absorb or emit any radiation but serves as a transparent pipe guiding the radiative energy from the emitter. At the same gap between an emitter and an absorber, we observe that near-field thermal energy transfer with thermal extraction can be enhanced by around 1 order of magnitude, compared to the case without thermal extraction. The novel thermal extraction scheme has important practical implications in a variety of technologies, e.g., thermophotovoltaic energy conversion, radiative cooling, thermal infrared imaging, and heat assisted magnetic recording.

  2. LPA Beamformer for Tracking Nonstationary Accelerated Near-Field Sources

    Directory of Open Access Journals (Sweden)

    Amira S. Ashour

    2014-01-01

    Full Text Available In this paper, a computationally very efficient algorithm for direction of arrival (DOA as well as range parameter estimation is proposed for near-field narrowband nonstationary accelerated moving sources. The proposed algorithm based on the local polynomial approximation (LPA beamformer, which proves its efficiency with far-field applications. The LPA estimates the instantaneous values of the direction of arrival, angular velocity, acceleration as well as the range parameters of near-field sources using weighted least squares approach which based on Taylor series. The performance efficiency of the LPA beamformer to estimate the DOAs of near-field sources is evaluated and compared with the Recursive Expectation-Maximization (REM method. The comparison is done using standard deviation of DOA estimation error as well as for range versus signal to noise ratio (SNR. The simulation results show that LPA beamformer outperform REM1 in signal-to-noise ratio requirements.

  3. Calculations of quasi-particle spectra of semiconductors under pressure

    DEFF Research Database (Denmark)

    Christensen, Niels Egede; Svane, Axel; Cardona, M.;

    2011-01-01

    to experiments and represents a significant improvement over ‘‘single-shot’’ GW calculations using local density approximation (LDA) start wavefunctions. The QSGW approximation is compared to LDA bands for awide-gap material (CuAlO2) and materialswith very small gaps, PbX (X=S, Se, and Te). For wide......-gap materials QSGW overestimates the gaps by 0.3–0.8 eV, an error which is ascribed to the omission of ‘‘vertex corrections.’’ This is confirmed by calculations of excitonic effects, by solving the Bethe-Salpeter equation. The LDA error in predicting the binding energy of the Cu-3d states is examined......Different approximations in calculations of electronic quasiparticle states in semiconductors are compared and evaluated with respect to their validity in predictions of optical properties. The quasi-particle self-consistent GW (QSGW) approach yields values of the band gaps which are close...

  4. Image Formation in Second-Harmonic Near-Field Microscopy

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Lozovski, Valeri Z.; Pedersen, Kjeld;

    1999-01-01

    A macroscopic self-consistent approach that enables one to rigorously describe image formation in scanning near-field optical second-harmonic generation microscopy is developed. The self-consistent second-harmonic field is determined by taking into account both the linear and nonlinear contributi......A macroscopic self-consistent approach that enables one to rigorously describe image formation in scanning near-field optical second-harmonic generation microscopy is developed. The self-consistent second-harmonic field is determined by taking into account both the linear and nonlinear...

  5. Near-field environment/processes working group summary

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, W.M. [Center for Nuclear Waste Regulatory Analyses, San Antonio, TX (United States)

    1995-09-01

    This article is a summary of the proceedings of a group discussion which took place at the Workshop on the Role of Natural Analogs in Geologic Disposal of High-Level Nuclear Waste in San Antonio, Texas on July 22-25, 1991. The working group concentrated on the subject of the near-field environment to geologic repositories for high-level nuclear waste. The near-field environment may be affected by thermal perturbations from the waste, and by disturbances caused by the introduction of exotic materials during construction of the repository. This group also discussed the application of modelling of performance-related processes.

  6. Near-field measurement of microwave active devices

    OpenAIRE

    Gasquet, D.; Nativel, L.; Arcambal, C.; Castagné, M.; Dhondt, F; Mazari, B.; Eudeline, P

    2000-01-01

    A completely new near field mapping system based on micro monopole antenna has been developed in order to determine the electric near-field at the surface of MMIC. The possibilities of this innovative experimental setup are shown by 2D mapping of a bend 5 line deposited on GaAs substrate and a coupled-line filter on Duroid 6002. These are supported by 3D electromagnetic simulations. We finally give some results obtained on a real MMIC with a medium resolution of 50µm. The industrial applicat...

  7. Near field communication recent developments and library implications

    CERN Document Server

    McHugh, Sheli

    2014-01-01

    Near Field Communication is a radio frequency technology that allows objects, such as mobile phones, computers, tags, or posters, to exchange information wirelessly across a small distance. This report on the progress of Near Field Communication reviews the features and functionality of the technology and summarizes the broad spectrum of its current and anticipated applications. We explore the development of NFC technology in recent years, introduce the major stakeholders in the NFC ecosystem, and project its movement toward mainstream adoption. Several examples of early implementation of NFC

  8. Percolation of optical excitation mediated by near-field interactions

    CERN Document Server

    Naruse, Makoto; Takahashi, Taiki; Aono, Masashi; Akahane, Kouichi; D'Acunto, Mario; Hori, Hirokazu; Thylen, Lars; Katori, Makoto; Ohtsu, Motoichi

    2016-01-01

    Optical excitation transfer in nanostructured matter has been intensively studied in various material systems for versatile applications. Herein, we discuss the percolation of optical excitations in randomly organized nanostructures caused by optical near-field interactions governed by Yukawa potential in a two-dimensional stochastic model. The model results demonstrate the appearance of two phases of percolation of optical excitation as a function of the localization degree of near-field interaction. Moreover, it indicates sublinear scaling with percolation distance when the light localization is strong. The results provide fundamental insights into optical excitation transfer and will facilitate the design and analysis of nanoscale signal-transfer characteristics.

  9. Effects of optical variables in immersion lens-based near-field optics.

    Science.gov (United States)

    Kim, Wan-Chin; Yoon, Yong-Joong; Choi, Hyun; Park, No-Cheol; Park, Young-Pil

    2008-09-01

    We analyze the effects of optical variables, such as illumination state, focal position variation, near-field air-gap height, and refractive index mismatch, in immersion lens-based near-field optics on the resultant field propagation characteristics, including spot size, focal depth, and aberrations. First, to investigate the general behaviors of various incident polarization states, focused fields near the focal planes in simple two- or three-layered media structures are calculated under considerations of refractive index mismatch, geometric focal position variations, and air-gap height in a multi-layered medium. Notably, for solid immersion near-field optics, although purely TM polarized illumination generates a stronger and 15% smaller beam spot size in the focal region than in the case of circularly polarized incident light, the intensity of the focused field decreases sharply from the interface between air and the third medium. For the same optical configurations, we show that changes in geometric focal position to the recording or detecting medium increases focal depth. Finally, through focused field analysis on a ROM (read-only memory) and a RW (rewritable) medium, compound effects of considered variables are discussed. The resultant field propagation behaviors described in this study may be applicable to the design of either highly efficient reflection or transmission near-field optics for immersion lens based information storage, microscopy and lithographic devices. PMID:18773004

  10. A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters

    Science.gov (United States)

    Huang, Wensheng; Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

    2013-01-01

    This paper presents a new method for analyzing near-field Faraday probe data obtained from Hall thrusters. Traditional methods spawned from far-field Faraday probe analysis rely on assumptions that are not applicable to near-field Faraday probe data. In particular, arbitrary choices for the point of origin and limits of integration have made interpretation of the results difficult. The new method, called iterative pathfinding, uses the evolution of the near-field plume with distance to provide feedback for determining the location of the point of origin. Although still susceptible to the choice of integration limits, this method presents a systematic approach to determining the origin point for calculating the divergence angle. The iterative pathfinding method is applied to near-field Faraday probe data taken in a previous study from the NASA-300M and NASA-457Mv2 Hall thrusters. Since these two thrusters use centrally mounted cathodes the current density associated with the cathode plume is removed before applying iterative pathfinding. A procedure is presented for removing the cathode plume. The results of the analysis are compared to far-field probe analysis results. This paper ends with checks on the validity of the new method and discussions on the implications of the results.

  11. Near-field thermal radiation between homogeneous dual uniaxial electromagnetic metamaterials

    Science.gov (United States)

    Chang, Jui-Yung; Basu, Soumyadipta; Yang, Yue; Wang, Liping

    2016-06-01

    Recently, near-field thermal radiation has attracted much attention in several fields since it can exceed the Planck blackbody limit through the coupling of evanescent waves. In this work, near-field radiative heat transfer between two semi-infinite dual uniaxial electromagnetic metamaterials with two different material property sets is theoretically analyzed. The near-field radiative heat transfer is calculated using fluctuational electrodynamics incorporated with anisotropic wave optics. The underlying mechanisms, namely, magnetic hyperbolic mode, magnetic surface polariton, electrical hyperbolic mode, and electrical surface polariton, between two homogeneous dual uniaxial electromagnetic metamaterials are investigated by examining the transmission coefficient and the spectral heat flux. The effect of vacuum gap distance is also studied, which shows that the enhancement at smaller vacuum gap is mainly due to hyperbolic mode and surface plasmon polariton modes. In addition, the results show that the contribution of s-polarized waves is significant and should not be excluded due to the strong magnetic response regardless of vacuum gap distances. The fundamental understanding and insights obtained here will facilitate the finding and application of novel materials for near-field thermal radiation.

  12. Phase transition and elastic properties of zinc sulfide under high pressure from first principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Wei [Hubei Univ. of Education, Wuhan (China). Dept. of Physics and Electronics; Chinese Academy of Engineering Physics, Mianyang (China). Inst. of Fluid Physics; Song, Jin-Fan; Wang, Ping; Lu, Cheng; Lu, Zhi-Wen [Nanyang Normal Univ. (China). Dept. of Physics; Tan, Xiao-Ming [Ludong Univ., Yantai (China). Dept. of Physics

    2011-10-15

    A theoretical investigation on structural and elastic properties of zinc sulfide semiconductor under high pressure is performed by employing the first-principles method based on the density functional theory. The calculated results show that the transition pressure P{sub t} for the structural phase transition from the B3 structure to the B1 structure is 17.04 GPa. The calculated values are generally speaking in good agreement with experiments and with similar theoretical calculations. (orig.)

  13. Cesium under pressure: First-principles calculation of the bcc-to-fcc phase transition

    Science.gov (United States)

    Carlesi, S.; Franchini, A.; Bortolani, V.; Martinelli, S.

    1999-05-01

    In this paper we present the ab initio calculation of the structural properties of cesium under pressure. The calculation of the total energy is done in the local-density approximation of density-functional theory, using a nonlocal pseudopotential including the nonlinear core corrections proposed by Louie et al. The calculation of the pressure-volume diagram for both bcc and fcc structures allows us to prove that the transition from bcc to fcc structure is a first-order transition.

  14. Prediction of near field overpressure from quarry blasting

    OpenAIRE

    Segarra Catasús, Pablo; Domingo Perlado, Jesus Felix; López Sánchez, Lina María; Sanchidrián Blanco, José Angel; Ortega Romero, Marcelo

    2010-01-01

    This paper investigates the propagation of airblast or pressure waves in air produced by bench blasting (i.e. detonation of the explosive in a row of blastholes, breaking the burden of rock towards the free vertical face of the block). Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at which the detonation sequence proceeds along the bench) and the polar coordinates of the position of interest (distance to the source and azimuth with...

  15. NEAR-FIELD ACOUSTIC HOLOGRAPHY FOR SEMI-FREE ACOUSTIC FIELD BASED ON WAVE SUPERPOSITION APPROACH

    Institute of Scientific and Technical Information of China (English)

    LI Weibing; CHEN Jian; YU Fei; CHEN Xinzhao

    2006-01-01

    In the semi-free acoustic field, the actual acoustic pressure at any point is composed of two parts: The direct acoustic pressure and the reflected acoustic pressure. The general acoustic holographic theories and algorithms request that there is only the direct acoustic pressure contained in the pressure at any point on the hologram surface, consequently, they cannot be used to reconstruct acoustic source and predict acoustic field directly. To take the reflected pressure into consideration, near-field acoustic holography for semi-free acoustic field based on wave superposition approach is proposed to realize the holographic reconstruction and prediction of the semi-free acoustic field, and the wave superposition approach is adopted as a holographic transform algorithm. The proposed theory and algorithm are realized and verified with a numerical example,and the drawbacks of the general theories and algorithms in the holographic reconstruction and prediction of the semi-free acoustic field are also demonstrated by this numerical example.

  16. Effective Algorithm for Calculation of Minimum Miscibility Pressure

    DEFF Research Database (Denmark)

    Jessen, Kristian; Michelsen, Michael Locht; Stenby, Erling Halfdan

    1998-01-01

    significantly and is clearly superior to other methods described in the literature. For a 15 component fluid description the MMP is determined within a few seconds on a PC. Hence the algorithm offers an efficient tool for projects where a large number of MMP calculations are needed (e.g. lumping and gas...... enrichment studies). A case study is presented based on a real reservoir fluid for which PVT studies, swelling test and slimtube experiments have been performed. The study aims at investigating the influence of the characterization, tuning and lumping procedure used for generating a fluid description...... on the prediction of the MMP. Based on the generated fluid description, a gas enrichment study is presented where the optimum mixture of two available injection gasses is determined aiming to optimize the gas injection project....

  17. Wideband scalable probe for Spherical Near-Field Antenna measurements

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Pivnenko, Sergey; Breinbjerg, Olav

    2011-01-01

    The paper presents a design of an open-boundary quad-ridged horn to be used as a wideband scalable dual-linearly polarized probe for spherical near-field antenna measurements. With a new higher-order probe correction technique developed at the Technical University of Denmark, the probe will enabl...

  18. Near-field characterization of photonic crystal Y-splitters

    DEFF Research Database (Denmark)

    Volkov, V. S.; Bozhevolnyi, S. I.; Borel, Peter Ingo;

    2005-01-01

    A scanning near-field optical microscope (SNOM) is used to directly map the propagation of light in a specially designed 50/50 photonic crystal (PC) Y-splitter fabricated on silicon-on-insulator (SOI) wafers. SNOM images are obtained for TE- and TM-polarized light in the wavelength range 1425-157...

  19. Epidermal electronics with advanced capabilities in near-field communication.

    Science.gov (United States)

    Kim, Jeonghyun; Banks, Anthony; Cheng, Huanyu; Xie, Zhaoqian; Xu, Sheng; Jang, Kyung-In; Lee, Jung Woo; Liu, Zhuangjian; Gutruf, Philipp; Huang, Xian; Wei, Pinghung; Liu, Fei; Li, Kan; Dalal, Mitul; Ghaffari, Roozbeh; Feng, Xue; Huang, Yonggang; Gupta, Sanjay; Paik, Ungyu; Rogers, John A

    2015-02-25

    Epidermal electronics with advanced capabilities in near field communications (NFC) are presented. The systems include stretchable coils and thinned NFC chips on thin, low modulus stretchable adhesives, to allow seamless, conformal contact with the skin and simultaneous capabilities for wireless interfaces to any standard, NFC-enabled smartphone, even under extreme deformation and after/during normal daily activities.

  20. THz near-field Faraday imaging in hybrid metamaterials

    NARCIS (Netherlands)

    Kumar, N.; Strikwerda, A.C.; Fan, K.; Zhang, X.; Averitt, R.D.; Planken, P.C.M.; Adam, A.J.L.

    2012-01-01

    We report on direct measurements of the magnetic near-field of metamaterial split ring resonators at terahertz frequencies using a magnetic field sensitive material. Specifically, planar split ring resonators are fabricated on a single magneto-optically active terbium gallium garnet crystal. Normall

  1. COUPLEX2 test case modeling the near field

    International Nuclear Information System (INIS)

    We present here the model to be used for the second level COUPLEX test case. It is based on a Near Field computation, taking into account the glass dissolution of vitrified waste, and the congruent release of several nuclides (including filiation chains), with their transport through the geological barrier. (author)

  2. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    Energy Technology Data Exchange (ETDEWEB)

    Bühler, Stefan; Obrist, Dominik; Kleiser, Leonhard [Institute of Fluid Dynamics, ETH Zurich, 8092 Zurich (Switzerland)

    2014-08-15

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re{sub D} = 18 100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data.

  3. Calculation of coolant flow in a nuclear reactor pressure collector

    International Nuclear Information System (INIS)

    Effect of output lattice resistance and a relative height of the collector on peculiarities of liquid flow and distribution of coolant flow rate in a distribution collector of a reactor has been investigated. Numerical integration of two-dimensional equations of coolant flow in a model of the distribution collector and in the inlet annular channel ignoring azimuthal perturbations at the inlet has been carried out. The calculations showed that, when increasing the relative height of the collector, the vortex was formed at the inlet of the collector due to the sudden flow rotation at the outlet from the inlet annular channel. The inlet vortex causes decrease of the flow rate at the collector periphery down to inverse stream formation. Application of displacers at the bottom of the collector leads to decreasing flow rate in the center and to levelling flow rate nonuniformity over the whole collector. Perturbation of only radial flow at the inlet leads to formation of vortices with the vertical axis near the center of the collector and to decrease of the rate at the outlet near the vortex region

  4. Near-field tsunami forecasting using offshore tsunami data from the 2011 Tohoku earthquake

    Science.gov (United States)

    Tsushima, H.; Hayashi, Y.; Hirata, K.; Baba, T.; Ohta, Y.; Iinuma, T.; Hino, R.; Tanioka, Y.; Sakai, S.; Shinohara, M.; Kanazawa, T.; Maeda, K.

    2012-12-01

    Real-time tsunami forecasting is one of the effective ways to mitigate tsunami disasters. Transmission of a tsunami warning based on rapid and accurate tsunami forecasting to coastal communities helps the residents to make the decisions about their evacuation behaviors. Offshore tsunami data take an important role in tsunami forecasting. Tsunamis can be detected at offshore stations earlier than at coastal sites, and the data provide direct information about the impeding tsunamis. When the 2011 Tohoku earthquake occurred, the large tsunamis were clearly observed at various offshore observatories around Japan, such as cabled ocean bottom pressure gauges (OBPGs), GPS buoys and DART. In this study, we retrospectively applied an algorithm of near-field tsunami forecasting (Tsushima et al., 2009, 2012, JGR) to the offshore tsunami data from the 2011 Tohoku earthquake to examine how the algorithm contributes to tsunami forecasting of M9 earthquakes. Our tsunami forecasting algorithm is based on a source estimation. For the algorithm, offshore tsunami waveform data are inverted for spatial distribution of an initial sea-surface displacement, and then coastal tsunami waveforms are synthesized from the estimated source and pre-computed Green's functions by a linear superposition. No assumptions concerning the fault geometry and the size of an earthquake are required in the algorithm. The predictions are repeated by progressively updating the offshore tsunami waveform data. Because individual predictions can be calculated within a few minutes, tsunami predictions can be updated at short intervals of time, thus providing successive tsunami predictions with improved accuracy. We retrospectively applied our algorithm to the tsunami data recorded at 13 offshore stations (6 OBPGs, 6 GPS buoys, and 1 DART) during the 2011 Tohoku tsunami event. As a result of the application made 20 minutes after the earthquake, tsunamis with heights of 5-10 m were forecasted at the coastal sites

  5. Nanoscale mechanical actuation and near-field read-out of photonic crystal molecules

    Science.gov (United States)

    Petruzzella, M.; La China, F.; Intonti, F.; Caselli, N.; De Pas, M.; van Otten, F. W. M.; Gurioli, M.; Fiore, A.

    2016-09-01

    We employed the contact forces induced by a near-field tip to tune and probe the optical resonances of a mechanically compliant photonic crystal molecule. Here, the pressure induced by the near-field tip is exploited to control the spectral proprieties of the coupled cavities in an ultrawide spectral range, demonstrating a reversible mode shift of 37.5 nm . Besides, by monitoring the coupling strength variation due to the vertical nanodeformation of the dielectric structure, distinct tip-sample interaction regimes have been unambiguously reconstructed with a nano-Newton sensitivity. These results demonstrate an optical method for mapping mechanical forces at the nanoscale with a lateral spatial resolution below 100 nm.

  6. Numerical simulations of near-field blast effects using kinetic plates

    International Nuclear Information System (INIS)

    Numerical simulations using two hydrocodes were compared to near-field measurements of blast impulse associated with ideal and non-ideal explosives to gain insight into testing results and predict untested configurations. The recently developed kinetic plate test was designed to measure blast impulse in the near-field by firing spherical charges in close range from steel plates and probing plate acceleration using laser velocimetry. Plate velocities for ideal, non-ideal and aluminized explosives tests were modeled using a three dimensional hydrocode. The effects of inert additives in the explosive formulation were modeled using a 1-D hydrocode with multiphase flow capability using Lagrangian particles. The relative effect of particle impact on the plate compared to the blast wave impulse is determined and modeling is compared to free field pressure results.

  7. High-rectification near-field thermal diode using phase change periodic nanostructure

    Science.gov (United States)

    Ghanekar, Alok; Ji, Jun; Zheng, Yi

    2016-09-01

    We theoretically demonstrate workings of a near-field thermal rectification device that uses a phase change material to achieve asymmetry in radiative heat transfer. We exploit the temperature dependent dielectric properties of VO2 due to metal-insulator transition near 341 K. Analogous to an electrical diode, heat transfer coefficient is high in one direction while it is considerably small when the polarity of temperature gradient is reversed. We show that thermal rectification can be greatly enhanced by using 1-D rectangular and triangular VO2 surface gratings. With the introduction of periodic grating, rectification ratio is dramatically enhanced in the near-field due to reduced tunneling of surface waves across the interfaces for negative polarity. Our calculations predict that for minimal temperature difference of 20 K, the rectification ratio as high as 16 can be obtained, and it is maximum in existing literature for comparable operating temperatures and separation.

  8. Numerical Simulations of Blast Loads from Near-Field Ground Explosions in Air

    Science.gov (United States)

    Dobrociński, Stanisław; Flis, Leszek

    2015-12-01

    Numerical simulations of air blast loading in the near-field acting on the ground have been performed. A simplified blast model based on empirical blast loading data representing spherical and hemispherical explosive shapes has been simulated. Conwep is an implementation of the empirical blast models presented by Kingery and Bulmash, which is also implemented in the commercial code LS-DYNA based on work done by Rahnders-Pehrson and Bannister. This makes it possible to simulate blast loads acting on structures representing spherical and hemispherical explosive shapes of TNT with reasonable computational effort as an alternative to the SPH and Eulerian model. The CPU time for the simplified blast model is however considerably shorter and may still be useful in time consuming concept studies. Reasonable numerical results using reasonable model sizes can be achieved not only for modelling near-field explosions in air but most areas of geotechnical. Calculation was compared with blast SPH and Eulerian model.

  9. Structural and electronic properties of solid naphthalene under pressure: density functional calculations

    Science.gov (United States)

    Xiao, Ling-Ping; Zeng, Zhi; Chen, Xiao-Jia

    2016-06-01

    The pressure effect on the geometrical and electronic structures of crystalline naphthalene is calculated up to 30 GPa by performing density functional calculations. The lattice parameters a, b, and c, decrease by 1.77 Å (-20.4%), 0.85 Å (-14.1%), and 0.91 Å (-8.2%), respectively, while the monoclinic angle β increases by 3.95° in this pressure region. At the highest pressure of 30 GPa the unit cell volume decreases by 62.7%. The detailed analysis of the molecular arrangement within crystal structure reveals that the molecular motion becomes more and more localized, and hints towards the evolution of intermolecular interaction with pressure. Moreover, the electronic structure of naphthalene under high pressure is also discussed. A pressure induced decrease of the band gap is observed.

  10. Active thermal extraction of near-field thermal radiation

    Science.gov (United States)

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-02-01

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at subwavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far field. Our study demonstrates an approach to manipulate thermal radiation that could find applications in thermal management.

  11. Rewritable organic films for near-field recording

    Science.gov (United States)

    Lee, Hyo Won; Kim, Young Mi; Jeon, Dong Ju; Kim, Eunkyoung; Kim, Jeongyong; Park, Kangho

    2003-01-01

    Photochromic thin films were prepared for near-field recording. Acetyl substituted diarylethene were synthesized from 1,2-bis(2-methylbenzo[ b]thiophene-3-yl)hexafluorocyclopentene in one step. Transparent and homogeneous thin films were coated on a substrate by vacuum deposition method. A colorless vacuum deposited diarylethene film turned to deep red hue upon exposure to a UV light. Near-field scanning optical microscopy (NSOM) was used to characterize nanoscale color change of the films. NSOM images showed distinct recording mark by 514 nm laser with mark speed of 30 ms. The records were completely erased upon excitation with a UV light, and rewritable with visible light (514 nm) on a UV activated colored film.

  12. Near-Field Source Localization Using a Special Cumulant Matrix

    Science.gov (United States)

    Cui, Han; Wei, Gang

    A new near-field source localization algorithm based on a uniform linear array was proposed. The proposed algorithm estimates each parameter separately but does not need pairing parameters. It can be divided into two important steps. The first step is bearing-related electric angle estimation based on the ESPRIT algorithm by constructing a special cumulant matrix. The second step is the other electric angle estimation based on the 1-D MUSIC spectrum. It offers much lower computational complexity than the traditional near-field 2-D MUSIC algorithm and has better performance than the high-order ESPRIT algorithm. Simulation results demonstrate that the performance of the proposed algorithm is close to the Cramer-Rao Bound (CRB).

  13. Near-field levitated quantum optomechanics with nanodiamonds

    Science.gov (United States)

    Juan, M. L.; Molina-Terriza, G.; Volz, T.; Romero-Isart, O.

    2016-08-01

    We theoretically show that the dipole force of an ensemble of quantum emitters embedded in a dielectric nanosphere can be exploited to achieve near-field optical levitation. The key ingredient is that the polarizability from the ensemble of embedded quantum emitters can be larger than the bulk polarizability of the sphere, thereby enabling the use of repulsive optical potentials and consequently the levitation using optical near fields. In levitated cavity quantum optomechanics, this could be used to boost the single-photon coupling by combining larger polarizability to mass ratio, larger field gradients, and smaller cavity volumes while remaining in the resolved sideband regime and at room temperature. A case study is done with a nanodiamond containing a high density of silicon-vacancy color centers that is optically levitated in the evanescent field of a tapered nanofiber and coupled to a high-finesse microsphere cavity.

  14. Nanoscale Spectroscopy with a Scanning Near-Field Infrared Microscope

    Science.gov (United States)

    Michaels, Chris; Richter, Lee; Cavanagh, Richard; Stranick, Stephan

    2001-03-01

    The development of a scanning near-field microscope that allows the measurement of infrared spectra with nanoscale spatial resolution will be described. This instrument couples the spatial resolution of a scanning probe microscope with the chemical specificity of vibrational spectroscopy. This combination allows the in situ mapping of chemical functional groups with subwavelength spatial resolution. Infrared transmission images of a micropatterned thin gold film will be presented that demonstrate spatial resolution of λ/10 at 3.4 micrometers in the absence of artifacts due to topography-induced contrast. Near-field infrared absorption spectra of thin polymer films that demonstrate sensitivity sufficient for sub-diffraction absorption imaging in the aliphatic and aromatic C-H stretching regions will also be presented. Images of thin film polymer blends and nanocomposites acquired in the C-H stretching region will be used to benchmark the nanoscale chemical imaging capabilities of this microscope.

  15. Nanorod near-field radiative heat exchange analysis

    International Nuclear Information System (INIS)

    A theoretical method for cylinder-to-cylinder radiative heat exchange is formulated. The method utilized was a modified version of a previously published numerical method for near-field sphere-to-sphere radiative exchange. Modifications were made to the numerical procedure to make it applicable to cylindrical geometry of nanorods. Nanorods investigated had length to diameter ratios of 3:1 and 7:1. The heat exchange of nanorods is plotted vs. gap to assess the impact of near-field radiative transfer as gap decreases. Graphical results of energy vs. nanorod radii are also presented. A nanorod-to-plane configuration is estimated utilizing a nanorod asymptotic method. The nanorod-to-nanorod method approximates a nanorod-to-plane geometric configuration when one nanorod radii is held constant, and the second nanorod radii is iteratively increased until the corresponding radiative exchange converges.

  16. Calculation of thermal conductivity of polymer solutions in a wide range of temperatures and pressure

    International Nuclear Information System (INIS)

    Present article is devoted to calculation of thermal conductivity of polymer solutions in a wide range of temperatures and pressure. The dependence of thermal conductivity of polymers on temperature and pressure was studied. The dependence of thermal conductivity of polymers on molar mass was studied as well.

  17. A finite volume method for calculating transonic potential flow around wings from the pressure minimum integral

    Science.gov (United States)

    Eberle, A.

    1978-01-01

    Analysis of the pressure minimum integral in the calculation of three-dimensional potential flow around wings makes it possible to use non-rectangular mesh networks for distributing the three-dimensional potential into discrete points. The method is comparatively easily expanded to the treatment of realistic airplane configurations. Shock-pressure affected pressure distributions on any wings are determined with accuracy using this method.

  18. A near field 3D radar imaging technique

    OpenAIRE

    Broquetas Ibars, Antoni

    1993-01-01

    The paper presents an algorithm which recovers a 3D reflectivity image of a target from near-field scattering measurements. Spherical wave nearfield illumination is used, in order to avoid a costly compact range installation to produce a plane wave illumination. The system is described and some simulated 3D reconstructions are included. The paper also presents a first experimental validation of this technique. Peer Reviewed

  19. Near-field acoustic holography analysis of modulated sound source

    Institute of Scientific and Technical Information of China (English)

    MAO Rongfu; ZHU Haichao; DU Xianghua; ZHU Haipeng

    2011-01-01

    When conventional near-field acoustic holography (NAH) technique is appliedto sound field induced by modulated signal, the modulating frequency can not be revealed by the reconstructed results. To solve the problem, a NAH analysis methodology for modulated sound source was proposed. Firstly, Hilbert transform was introduced to demodulate the signal, and then modulating component was reconstructed by NAH technique. Both numerical simulation and experiment results demonstrate that accurate reconstruction analysis can be obtained by the proposed method.

  20. Use of Near Field Communication in emergency Rescue situations

    DEFF Research Database (Denmark)

    Kramp, Gunnar

    2006-01-01

    Near Field Communication (NFC) where the placement of two devices in close proximity of each other makes it possible for two devices to exhange and share information, opens up for a variety of transparent and intuitive interaction possibilities. However, as we have identified in the palcom projec...... [1], instant and appropriate feedback regarding state of the connection and identification of which devices are connected to each other, is crucial for use....

  1. Near-Field Photothermal Heating with a Plasmonic Nanofocusing Probe

    Science.gov (United States)

    Chen, Xiang; Dong, Biqing; Balogun, Oluwaseyi

    2016-03-01

    Noble metal nanostructures support plasmon resonances—collective oscillation of charge carriers at optical frequencies—and serve as effective tools to create bright light sources at the nanoscale. These sources are useful in broad application areas including, super-resolution imaging and spectroscopy, nanolithography, and near-field optomechanical transducers. The feasibility of these applications relies on efficient conversion of free-space propagating light to plasmons. Recently, we demonstrated a hybrid nanofocusing scheme for efficient coupling of light to plasmons at the apex of a scanning probe. In the approach, free-space light is coupled to propagating surface plasmon polaritons (SPPs) on the tapered shaft of the scanning probe. The SPPs propagate adiabatically towards the probe tip where they are coupled to localized plasmons (LSPs). The nanofocusing scheme was explored in a near-field scanning optical microscope for super-resolution imaging, near-field transduction of nanomechanical vibrations, and local detection of ultrasound. Owing to the strong concentration of light at the probe, significant heating of the tip and a sample positioned in the optical near-field is expected. This paper investigates the local heating produced by the plasmonic nanofocusing probe under steady-state conditions using the tip-enhanced Raman scattering approach. In addition, a finite element model is explored to study the coupling of free propagating light to LSPs, and to estimate the temperature rise expected in a halfspace heated by absorption of the LSPs. This study has implications for exploring the plasmonic nanofocusing probe in heat-assisted nanofabrication and fundamental studies of nanoscale heat transport in materials.

  2. Near-field photometry for organic light-emitting diodes

    Science.gov (United States)

    Li, Rui; Harikumar, Krishnan; Isphording, Alexandar; Venkataramanan, Venkat

    2013-03-01

    Organic Light Emitting Diode (OLED) technology is rapidly maturing to be ready for next generation of light source for general lighting. The current standard test methods for solid state lighting have evolved for semiconductor sources, with point-like emission characteristics. However, OLED devices are extended surface emitters, where spatial uniformity and angular variation of brightness and colour are important. This necessitates advanced test methods to obtain meaningful data for fundamental understanding, lighting product development and deployment. In this work, a near field imaging goniophotometer was used to characterize lighting-class white OLED devices, where luminance and colour information of the pixels on the light sources were measured at a near field distance for various angles. Analysis was performed to obtain angle dependent luminous intensity, CIE chromaticity coordinates and correlated colour temperature (CCT) in the far field. Furthermore, a complete ray set with chromaticity information was generated, so that illuminance at any distance and angle from the light source can be determined. The generated ray set is needed for optical modeling and design of OLED luminaires. Our results show that luminance non-uniformity could potentially affect the luminaire aesthetics and CCT can vary with angle by more than 2000K. This leads to the same source being perceived as warm or cool depending on the viewing angle. As OLEDs are becoming commercially available, this could be a major challenge for lighting designers. Near field measurement can provide detailed specifications and quantitative comparison between OLED products for performance improvement.

  3. Active Extraction of Near-field Thermal Radiation

    Science.gov (United States)

    Ding, Ding; Kim, Taeyong; Minnich, Austin

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at sub-wavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active radiative cooling (ARC) scheme to extract these modes to the far-field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far-field. We also provide further insights into our ARC scheme by applying the theoretical framework used for laser cooling of solids (LCS) to ARC. We show that LCS and ARC can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ARC. Using this framework, we examine the predictions of the formalism for LCS and ARC using realistic parameters and find that ARC can achieve higher efficiency and extracted power over a wide range of conditions. Our study demonstrates a new approach to manipulate near-field thermal radiation for thermal management.

  4. Short presentation on some researches activities about near field earthquakes

    International Nuclear Information System (INIS)

    The major hazard posed by earthquakes is often thought to be due to moderate to large magnitude events. However, there have been many cases where earthquakes of moderate and even small magnitude have caused very significant destruction when they have coincided with population centres. Even though the area of intense ground shaking caused by such events is generally small, the epicentral motions can be severe enough to cause damage even in well-engineered structures. Two issues are addressed here, the first being the identification of the minimum earthquake magnitude likely to cause damage to engineered structures and the limits of the near-field for small-to-moderate magnitude earthquakes. The second issue addressed is whether features of near-field ground motions such as directivity, which can significantly enhance the destructive potential, occur in small-to-moderate magnitude events. The accelerograms from the 1986 San Salvador (El Salvador) earthquake indicate that it may be non conservative to assume that near-field directivity effects only need to be considered for earthquakes of moment magnitude M 6.5 and greater. (author)

  5. Near-field thermal electromagnetic transport: An overview

    Science.gov (United States)

    Edalatpour, Sheila; DeSutter, John; Francoeur, Mathieu

    2016-07-01

    A general near-field thermal electromagnetic transport formalism that is independent of the size, shape and number of heat sources is derived. The formalism is based on fluctuational electrodynamics, where fluctuating currents due to thermal agitation are added to Maxwell's curl equations, and is thus valid for heat sources in local thermodynamic equilibrium. Using a volume integral formulation, it is shown that the proposed formalism is a generalization of the classical electromagnetic scattering framework in which thermal emission is implicitly assumed to be negligible. The near-field thermal electromagnetic transport formalism is afterwards applied to a problem involving three spheres with size comparable to the wavelength, where all multipolar interactions are taken into account. Using the thermal discrete dipole approximation, it is shown that depending on the dielectric function, the presence of a third sphere slightly affects the spatial distribution of power absorbed compared to the two-sphere case. A transient analysis shows that despite a non-uniform spatial distribution of power absorbed, the sphere temperature remains spatially uniform at any instant due to the fact that the thermal resistance by conduction is much smaller than the resistance by radiation. The formalism proposed in this paper is general, and could be used as a starting point for adapting solution methods employed in traditional electromagnetic scattering problems to near-field thermal electromagnetic transport.

  6. Near-Field Source Localization by Using Focusing Technique

    Science.gov (United States)

    He, Hongyang; Wang, Yide; Saillard, Joseph

    2008-12-01

    We discuss two fast algorithms to localize multiple sources in near field. The symmetry-based method proposed by Zhi and Chia (2007) is first improved by implementing a search-free procedure for the reduction of computation cost. We present then a focusing-based method which does not require symmetric array configuration. By using focusing technique, the near-field signal model is transformed into a model possessing the same structure as in the far-field situation, which allows the bearing estimation with the well-studied far-field methods. With the estimated bearing, the range estimation of each source is consequently obtained by using 1D MUSIC method without parameter pairing. The performance of the improved symmetry-based method and the proposed focusing-based method is compared by Monte Carlo simulations and with Crammer-Rao bound as well. Unlike other near-field algorithms, these two approaches require neither high-computation cost nor high-order statistics.

  7. High RF Magnetic Field Near-Field Microwave Microscope

    Science.gov (United States)

    Tai, Tamin; Mircea, Dragos I.; Anlage, Steven M.

    2010-03-01

    Near-field microwave microscopes have been developed to quantitatively image RF and microwave properties of a variety of materials on deep sub-wavelength scales [1]. Microscopes that develop high-RF magnetic fields on short length scales are useful for examining the fundamental electrodynamic properties of superconductors [2]. We are creating a new class of near-field microwave microscopes that develop RF fields on the scale of 1 Tesla on sub-micron length scales. These microscopes will be employed to investigate defects that limit the RF properties of bulk Nb materials used in accelerator cavities, and the nonlinear Meissner effect in novel superconductors. Work funded by the US Department of Energy. [1] S. M. Anlage, V. V. Talanov, A. R. Schwartz, ``Principles of Near-Field Microwave Microscopy,'' in Scanning Probe Microscopy: Electrical and Electromechanical Phenomena at the Nanoscale, Volume 1, edited by S. V. Kalinin and A. Gruverman (Springer-Verlag, New York, 2007), pp. 215-253. [2] D. I. Mircea, H. Xu, S. M. Anlage, ``Phase-sensitive Harmonic Measurements of Microwave Nonlinearities in Cuprate Thin Films,'' Phys. Rev. B 80, 144505 (2009).

  8. REFREP: a near-field model for a spent fuel repository

    International Nuclear Information System (INIS)

    A code package for near-field performance analysis of spent fuel disposal has been programmed. The conceptual models used are shortly described in connection with th model presentations. For more comprehensive descriptions the previous safety analysis and references therein are referred. The REFREP package consists of nine individual modules performing the following tasks: viewing and updating of the data files (UPDATE), calculating of the breaching times of canisters (CORRFLUX), calculating of stationary nuclide release rates using solubility values (MASSFLUX), calculating of actinide inventories from chain decay (INVENT), calculating of elemental inventories of actinides (ELEMENT), calculating of nuclide release rates according to congruent release (CONGRUNT), performing of sensitivity analysis for one variable (SENSIT), summing of release rates from individual canisters according to given probability distributions of canister breaching times (PROBREL), and forming a compact data file including all the input values (DATAOUT). The results have been shown to agree very well with the results of the previous safety analysis where near-field analysis was performed by means of separate codes and manual calculation. The REFREP model offers already at this stage some additional features to the old procedures and more versatile capabilities can easyly be added into the modular structure of the package. REFREP has been developed in a VAX-environment. Some changes in file handling might be necessary if the code is transferred to another computer

  9. On the slow dynamics of near-field acoustically levitated objects under High excitation frequencies

    Science.gov (United States)

    Ilssar, Dotan; Bucher, Izhak

    2015-10-01

    This paper introduces a simplified analytical model describing the governing dynamics of near-field acoustically levitated objects. The simplification converts the equation of motion coupled with the partial differential equation of a compressible fluid, into a compact, second order ordinary differential equation, where the local stiffness and damping are transparent. The simplified model allows one to more easily analyse and design near-field acoustic levitation based systems, and it also helps to devise closed-loop controller algorithms for such systems. Near-field acoustic levitation employs fast ultrasonic vibrations of a driving surface and exploits the viscosity and the compressibility of a gaseous medium to achieve average, load carrying pressure. It is demonstrated that the slow dynamics dominates the transient behaviour, while the time-scale associated with the fast, ultrasonic excitation has a small presence in the oscillations of the levitated object. Indeed, the present paper formulates the slow dynamics under an ultrasonic excitation without the need to explicitly consider the latter. The simplified model is compared with a numerical scheme based on Reynolds equation and with experiments, both showing reasonably good results.

  10. Development of a database system for the calculation of indicators of environmental pressure caused by transport

    DEFF Research Database (Denmark)

    Giannouli, Myrsini; Samaras, Zissis; Keller, Mario;

    2006-01-01

    The scope of this paper is to summarise a methodology developed for TRENDS (TRansport and ENvironment Database System-TRENDS). The main objective of TRENDS was the calculation of environmental pressure indicators caused by transport. The environmental pressures considered are associated with air...... emissions from the four main transport modes, i.e. road, rail, ships and air. In order to determine these indicators a system for calculating a range of environmental pressures due to transport was developed within a PC-based MS Access environment. Emphasis is given oil the latest features incorporated...

  11. Comparison between centrifuge near-field model test and its numerical analysis

    International Nuclear Information System (INIS)

    In this paper, hydro-mechanical coupled numerical simulation of the centrifuge near-field model test was conducted and its results were compared to the experimental results. Water infiltration in rock mass in numerical simulation was in good agreement with experimental observation. Expansion of rock and bentonite during water infiltration was also broadly reproduced by numerical simulation. However, decrease of swelling pressure around 100 equivalent years could not be reproduced. This result suggests that the time-dependent behavior of soft rock affected the bentonite behavior in a deposition hole. (author)

  12. Underwater hybrid near-field acoustical holography based on the measurement of vector hydrophone array

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hybrid near-field acoustical holography(NAH) is developed for reconstructing acoustic radiation from a cylindrical source in a complex underwater environment. In hybrid NAH,we combine statistically optimized near-field acoustical holography(SONAH) and broadband acoustical holography from intensity measurements(BAHIM) to reconstruct the underwater cylindrical source field. First,the BAHIM is utilized to regenerate as much acoustic pressures on the hologram surface as necessary,and then the acoustic pressures are taken as input to the formulation implemented numerically by SONAH. The main advantages of this technology are that the complex pressure on the hologram surface can be reconstructed without reference signal,and the measurement array can be smaller than the source,thus the practicability and efficiency of this technology are greatly enhanced. Numerical examples of a cylindrical source are demonstrated. Test results show that hybrid NAH can yield a more accurate reconstruction than conventional NAH. Then,an experiment has been carried out with a vector hydrophone array. The experimental results show the advantage of hybrid NAH in the reconstruction of an acoustic field and the feasibility of using a vector hydrophone array in an underwater NAH measurement,as well as the identification and localization of noise sources.

  13. Near-Field Characterization of Optical Micro/Nanofibres

    Institute of Scientific and Technical Information of China (English)

    MA Zhe; WANG Shan-Shan; YANG Qing; TONG Li-Min

    2007-01-01

    Near-field scanning optical microscopy is used to investigate the waveguiding properties of optical micro/nanofibres (MNFs) by means of detecting optical power carried by evanescent waves. Taper drawn silica and tellurite MNFs,supported on low-index substrates, are used to guide a 532-nm-wavelength light beam for the test. Modification of the single-mode condition of the MNF in the presence of a substrate is observed. Spatial modulation of the longitudinal field intensity (with a 195-nm period) near the output end of a 760-nm-diameter silica MNF is well resolved. Energy exchange through evanescent coupling between two parallel MNFs is also investigated.

  14. Planar Near-Field Measurements of Ground Penetrating Radar Antennas

    DEFF Research Database (Denmark)

    Meincke, Peter; Hansen, Thorkild

    2004-01-01

    Planar near-field measurements are formulated for a general ground penetrating radar (GPR) antenna. A total plane-wave scattering matrix is defined for the system consisting of the GPR antenna and the planar air-soil interface. The transmitting spectrum of the GPR antenna is expressed in terms...... of measurements obtained with a buried probe as the GPR antenna moves over a scan plane on the ground. A numerical example in which the scan plane is finite validates the expressions for the spectrum of the GPR antenna....

  15. Near field communication (NFC) from theory to practice

    CERN Document Server

    Coskun, Vedat; Ozdenizci, Busra

    2011-01-01

    This book provides the technical essentials, state-of-the-art knowledge, business ecosystem and standards of Near Field Communication (NFC)by NFC Lab - Istanbul research centre which conducts intense research on NFC technology. In this book, the authors present the contemporary research on all aspects of NFC, addressing related security aspects as well as information on various business models. In addition, the book provides comprehensive information a designer needs to design an NFC project, an analyzer needs to analyze requirements of a new NFC based system, and a programmer needs to implem

  16. Near-field Optical Imagigng and Chemical Analysis

    Science.gov (United States)

    Andres, La Rosa

    1998-03-01

    Identification of molecular structures in complex mixtures represents a major challenge in chemical research today. Microfabricated devices or lab-on-a-chip that perform chemical analysis allows dynamic sampling of picoliter microenvironments and separation. The long-term goals of nanochemistry down to the femtoliter scale involve refinement of the detection limit to single-molecule. Our approach consists in designing a very sensitive near-field optical microscope (NSOM-SIAM) to explore the mesoscopic properties of organic compounds. The validity, sensitivity and unique spatial resolution of this system will be discussed for multiple analyte chemosensing.

  17. Calculation of cardiac pressures using left ventricular ejection fraction (LVEF) derived from radionuclide angiography

    Energy Technology Data Exchange (ETDEWEB)

    Hommer, E.

    1981-04-01

    An attempt has been made to develop formulas to determine cardiac pressures in an undisturbed flow in patients without valvular or shunt diseases. These are based entirely on the results of left ventricular ejection fraction rates, permitting pressure analysis of several compartments at the same tine. According to BORER et al. they also enable determination of left ventricular 'Functional Reserve' after bycycle exercise as well as left ventricular 'Relaxation Reserve'. They support the views of NYHA in determining the grades of cardiac insufficiency proving the system- and low-pressure participation. A single formula for pulmonary flow can determine the pulmonary arterial pressure. The left ventricular enddiastolic pressure can also be exclusively calculated by values of left ventricular functions, thus both formulas may be used in disorders of the mitral valves. The possibility to calculate pressures of all the compartments of the heart from left ventricular ejection rate shows, that in undisturbed flow global heart function depends on left ventricular function. Therefore the mutual dependence of these formulas presents an intercompartimental pressure regulation of the heart through pulmonary flow and pulmonary vascular pressure, which leaves an aspect of autonomous cardiac regulation open to discussion.

  18. Laboratory measurement of a long term behavior in HLW near-field by centrifugal model test

    International Nuclear Information System (INIS)

    The objective of this paper is to evaluate the long term behavior of HLW near-field by the centrifugal model test. The model specimen consists of rock mass, bentonite buffer and model waste. The specimen was enclosed with the pressure vessel and centrifugal model tests were conducted at 30 G of centrifugal force field with confining pressures of 2 to 10 MPa and injecting water. As a result, we observed the strain of rock mass, swelling of bentonite and displacement of overpack, and these values did not converged more than 100 equivalent years. In addition, the measured values showed the confining pressure dependency. It is suggested that the stability of HLW in the bentonite buffer takes more than 100 years at least. (author)

  19. A Guided Mode View on Near-Field Scanning Optical Microscopy Measurements of Optical Magnetic Fields with Slit Probes

    OpenAIRE

    Stoffer, Remco; Hammer, Manfred; Ivanova, O. V.; Hoekstra, Hugo J.W.M.

    2010-01-01

    Recent Near-field Scanning Optical Microscopy (NSOM) experiments with slit metal coated probes claim to measure the out-of-plane optical magnetic field around a dielectric sample waveguide [1]. The observations can also be explained by mode overlap calculations.

  20. First-principles calculations of structural stability and mechanical properties of tungsten carbide under high pressure

    Science.gov (United States)

    Li, Xinting; Zhang, Xinyu; Qin, Jiaqian; Zhang, Suhong; Ning, Jinliang; Jing, Ran; Ma, Mingzhen; Liu, Riping

    2014-11-01

    The structural stability and mechanical properties of WC in WC-, MoC- and NaCl-type structures under high pressure are investigated systematically by first-principles calculations. The calculated equilibrium lattice constants at zero pressure agree well with available experimental and theoretical results. The formation enthalpy indicates that the most stable WC is in WC-type, then MoC-type finally NaCl-type. By the elastic stability criteria, it is predicted that the three structures are all mechanically stable. The elastic constants Cij, bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν of the three structures are studied in the pressure range from 0 to 100 GPa. Furthermore, by analyzing the B/G ratio, the brittle/ductile behavior under high pressure is assessed. Moreover, the elastic anisotropy of the three structures up to 100 GPa is also discussed in detail.

  1. Phase Envelope Calculations for Reservoir Fluids in the Presence of Capillary Pressure

    DEFF Research Database (Denmark)

    Lemus, Diego; Yan, Wei; Michelsen, Michael L.;

    2015-01-01

    Newton method is employed to solve the governing equations of the vapor-liquid equilibria coupled with the capillary pressure equation. For a stable and automatic construction of the phase envelope sensitivity analysis is used in each step. The developed algorithm can reliably generate not just...... the bubble and dew point curves but also other quality lines with vapor fractions between 0 and 1. The algorithm has been used to calculate the phase envelopes of binary, multicomponent and reservoir fluid systems for pore radius from 10 to 50 nm. The presence of capillary pressure changes the saturation...... mixtures in the presence of capillary pressure. The algorithm uses a rigorous equation of state (EoS) model, such as the Soave-Redlich-Kwong EoS, for phase equilibrium, and the Young-Lapace equation for the capillary pressure. The interfacial tension is calculated using a parachor based model. A full...

  2. High-pressure physical properties of magnesium silicate post-perovskite from ab initio calculations

    Indian Academy of Sciences (India)

    Zi-Jiang Liu; Xiao-Wei Sun; Cai-Rong Zhang; Jian-Bu Hu; Ling-Cang Cai; Qi-Feng Chen

    2012-08-01

    The structure, thermodynamic and elastic properties of magnesium silicate (MgSiO3) post-perovskite at high pressure are investigated with quasi-harmonic Debye model and ab initio method based on the density functional theory (DFT). The calculated structural parameters of MgSiO3 post-perovskite are consistent with the available experimental results and the recent theoretical results. The Debye temperature, heat capacity and thermal expansion coefficient at high pressures and temperatures are predicted using the quasi-harmonic Debye model. The elastic constants are calculated using stress–strain relations. A complete elastic tensor of MgSiO3 post-perovskite is determined in the wide pressure range. The calculated elastic anisotropic factors and directional bulk modulus show that MgSiO3 post-perovskite possesses high elastic anisotropy.

  3. Light depolarization induced by metallic tips in apertureless near-field optical microscopy and tip-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gucciardi, P G [CNR-Istituto per i Processi Chimico-Fisici, sezione Messina, Salita Sperone, Contrada Papardo, I-98158 Faro Superiore, Messina (Italy); Lopes, M; Deturche, R; Julien, C; Barchiesi, D; Chapelle, M Lamy de la [Institut Charles Delaunay-CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de Technologie de Troyes, 12 rue Marie Curie, BP2060, 10010 Troyes (France)

    2008-05-28

    We have investigated the depolarization effects of light scattered by sharp tips used for apertureless near-field optical microscopy. Dielectric and metal coated tips have been investigated and depolarization factors between 5 and 30% have been measured, changing as a function of the incident light polarization and of the tip shape. The experimental results are in good agreement with theoretical calculations performed by the finite element method, giving a near-field depolarization factor close to 10%. The effect of depolarization has been investigated in polarized tip-enhanced Raman spectroscopy (TERS) experiments; the depolarization gives rise to forbidden Raman modes in Si crystals.

  4. Cryogenic apparatus for study of near-field heat transfer

    Science.gov (United States)

    Kralik, T.; Hanzelka, P.; Musilova, V.; Srnka, A.; Zobac, M.

    2011-05-01

    For bodies spaced in vacuum at distances shorter than the wavelength of the thermal radiation, radiative heat transfer substantially increases due to the contribution of evanescent electromagnetic waves. Experimental data on heat transfer in near-field regime are scarce. We have designed a cryogenic apparatus for the study of heat transfer over microscopic distances between metallic and non-metallic surfaces. Using a mechanical positioning system, a planeparallel gap between the samples, concentric disks, each 35 mm in diameter, is set and varied from 100 to 103 μm. The heat transferred from the hot (10 - 100 K) to the cold sample (˜5 K) sinks into a liquid helium bath through a thermal resistor, serving as a heat flux meter. Transferred heat power within ˜2 nW/cm2 and ˜30 μW/cm2 is derived from the temperature drop along the thermal resistor. For tungsten samples, the distance of the near-field effect onset was inversely proportional to temperature and the heat power increase was observed up to three orders of magnitude greater than the power of far-field radiative heat transfer.

  5. Near-field thermoacoustic tomography of small animals

    Science.gov (United States)

    Kellnberger, Stephan; Hajiaboli, Amir; Razansky, Daniel; Ntziachristos, Vasilis

    2011-06-01

    Near-field radiofrequency thermoacoustic (NRT) tomography is a new imaging method that was developed to mitigate limitations of conventional thermoacoustic imaging approaches, related to hard compromises between signal strength and spatial resolution. By utilizing ultrahigh-energy electromagnetic impulses at ~20 ns duration along with improved energy absorption coupling in the near-field, this method can deliver high-resolution images without compromising signal to noise ratio. NRT is a promising modality, offering cost-effectiveness and ease of implementation and it can be conveniently scaled to image small animals and humans. However, several of the performance metrics of the method are not yet documented. In this paper, we characterize the expected imaging performance via numerical simulations based on a finite-integration time-domain (FITD) technique and experiments using tissue mimicking phantoms and different biological samples. Furthermore, we show for the first time whole-body tomographic imaging results from mice, revealing clear anatomical details along with highly dissipative inclusions introduced for control. The best spatial resolution achieved for those experiments was 150 µm.

  6. Aerosol dynamics in near-field aircraft plumes

    Science.gov (United States)

    Brown, R. C.; Miake-Lye, R. C.; Anderson, M. R.; Kolb, C. E.; Resch, T. J.

    1996-10-01

    A numerical model including gas phase HOx, NOx, and SOx chemistry; H2SO4-soot adsorption; binary H2SO4-H2O nucleation; aerosol coagulation; and vapor condensation is used to investigate aerosol formation and growth in near-field aircraft plumes. The plume flow field is treated using the JANNAF standard plume flow field code, SPF-II. Model results are presented for a Mach 2.4 high-speed civil transport at 18 km altitude and 85°N latitude and a subsonic Boeing 707 at 12.2 km, 47°N. The results, based on hydroxyl radical driven oxidation kinetics, indicate that 1-2% of the emitted SO2 is converted to H2SO4 in the near-field exhaust (1-2 s) and that for typical exhaust SO2 emission indices (≈1 g kg-fuel) the plume is supersaturated with respect to both the pure liquid acid and H2SO4/H2O solutions. Classical nucleation theory predicts high levels of small (0.3-0.6 nm radius) H2SO4/H2O embryos. Coagulation and gas-to-particle conversion are followed to provide estimates for the number density of activated soot particles capable of serving as condensation nuclei for contrail formation. Results are presented illustrating the dependence of water condensation on the number density and size distribution of activated exhaust soot nuclei.

  7. Review of Methods for Calculating Pressure Profiles of Explosive Air Blast and its Sample Application

    OpenAIRE

    Chock, Jeffrey Mun Kong

    1999-01-01

    Blast profiles and two primary methods of determining them were reviewed for use in the creation of a computer program for calculating blast pressures which serves as a design tool to aid engineers or analysts in the study of structures subjected to explosive air blast. These methods were integrated into a computer program, BLAST.F, to generate air blast pressure profiles by one of these two differing methods. These two methods were compared after the creation of the program and can conserv...

  8. Reactor pressure vessel strength calculations - comparing the AD/TRD and the ASME code. Pt. 1

    International Nuclear Information System (INIS)

    The dimensioning criteria applied in the various technical rules are illustrated by the example of a reactor pressure vessel nozzle, especially with a view to the characteristic data of the materials used. Using a detailed finite element analysis of the main coolant nozzle permits an evaluation of the different calculation methods. The second part of the report discusses safety problems, e.g. fatigue analysis, the necessity of carrying out 3D-elastoplastic FE calculations, or the assessment of transient loads on the reactor pressure vessel by means of a fracture-mechanical analysis. (orig./HP)

  9. French PWR 900 MWe pressure vessel surveillance neutron field characteristics TRIPOLI-3 calculations and experimental determination

    Energy Technology Data Exchange (ETDEWEB)

    Nimal, J.C.; Bourdet, L.; Zheng, S.H.; Vergnaud, T.; Kodeli, I. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie; Lloret, R.; Bevilacqua, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Reacteurs Experimentaux; Lefebvre, J.C. [Electricite de France (EDF), 69 - Villeurbanne (France)

    1994-12-31

    This paper presents an overview of the studies performed by CEA and EDF in the scope of the pressure vessel surveillance of the French nuclear power plants. The power plants are equipped with surveillance capsules, attached to the thermal shield. They contain the dosimeters and vessel material specimens for monitoring the effects of irradiation on the pressure vessel material. The Monte Carlo code TRIPOLI-3 is used with two nuclear data libraries to calculate the neutron flux, the steel damage and the dosimeter reaction rates, and takes into account the results of sensitivity/uncertainty calculations. 2 figs., 7 tabs., 10 refs.

  10. High-pressure behavior of solid nitrobenzene: Combined Raman spectroscopy and DFT-D calculations study

    Science.gov (United States)

    Wang, Wen-Peng; Liu, Fu-Sheng; Liu, Qi-Jun; Zhang, Lin-Ji; Wang, Yi-Gao; Liu, Zheng-Tang

    2016-09-01

    Nitrobenzene (NB), a simplest structure of the aromatic nitro compounds, was investigated as a model for understanding structural properties in nitro derivatives of benzene and anilines. Using the Raman spectroscopic technique, the vibrational modes of solid NB were examined under hydrostatic compression up to 10 GPa. The Raman spectra indicated that a subtle phase transition occurred around 5 GPa. Also, the dispersion corrected density functional theory (DFT-D) calculations were performed to provide further insight into pressure effects on the molecular geometry. The calculated data suggested that NB molecules were distorted, and molecular conformation was readjusted when the phase transition with vibrational changes took place under high-pressure.

  11. Theoretical Calculations for Structural, Elastic and Thermodynamic Properties of MgB2 under High Pressure

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We have investigated the structural and elastic properties of MgB2 under high pressures using the fullpotential linearized muffin-tin orbital (FP-LMTO) scheme within the generalized gradient approximation correction (GGA) in the frame of density functional theory. The calculated pressure dependence of the normalized volume is in excellent agreement with the experimental results. At the same time the elastic constants and acoustic anisotropy as a function of applied pressure are presented. Through the quasi-harmonic Debye model, we also investigate the thermodynamic properties of MgB2.

  12. Effect of hydrostatic pressure on structural and electronic properties of TGS crystals (first-principle calculations

    Directory of Open Access Journals (Sweden)

    B.Andriyevsky

    2007-01-01

    Full Text Available First principle calculations of the effect of hydrostatic pressure on the structural and electronic parameters of TGS crystals have been carried out within the framework of density functional theory using the CASTEP code. The volume dependence of total electronic energy E(V of the crystal unit cell satisfies the third-order Birch-Murnaghan isothermal equation of state. For the pressure range of -5...5 GPa, the bulk modulus was found to be equal to K=45 ± 5 GPa. The relative pressure changes of the unit cell parameters were found to be linear in the range of -5...5 GPa. Crossing of the pressure dependencies of enthalpy corresponding to the ferroelectric and non-ferroelectric phases at P=7.7 GPa testifies to the probable pressure induced phase transition in TGS crystal.

  13. Equations for calculating pressure loss; Ecuaciones para el calculo de perdida de carga

    Energy Technology Data Exchange (ETDEWEB)

    Cifre Vicens, B. [Hospital Son dureta, Plama de Mallorca, (Spain)

    1995-12-31

    Friction`s factor calculation is necessary for the determination of pressure loss, generally relied on the Colebrook equation which, since it is implicit, is difficult to apply using computers. A thorough review of the literature published since 1939 on the most commonly used equations is provided, establishing the validity range and relative error according to each author. The Churchill equation is recommended for use with computers as it allows calculations to be made in laminar and eddying flow areas. (Author) 17 refs.

  14. Multi-mode Scanning Near-field Optical Microscope

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A scanning near-field optical microscope using uncoated fiber tip is described, which can work in transmission and reflection configurations, both capable of working in illumination and collection-mode, so that either transparent or opaque sample can be investigated. Depending on different applications, either constant-gap or constant-height images can be achieved. A compact homemade translator permits to select interested area of sample in the range of 4mm×4mm. Working in the constant-height as well as transmission and collection-mode configuration, several kinds of samples such as holographic grating, liposome and zeolite were investigated. The experimental results revealed the dependence of the optical resolution of the SNOM on the tip-sample separation.

  15. Near-Field Cosmology with Metal-Poor Stars

    CERN Document Server

    Frebel, Anna

    2015-01-01

    The oldest, most metal-poor stars in the Galactic halo and satellite dwarf galaxies present an opportunity to explore the chemical and physical conditions of the earliest star forming environments in the Universe. We review the fields of stellar archaeology and dwarf galaxy archaeology by examining the chemical abundance measurements of various elements in extremely metal-poor stars. Focus on the carbon-rich and carbon-normal halo star populations illustrates how these provide insight into the Population III star progenitors responsible for the first metal enrichment events. We extend the discussion to near-field cosmology, which is concerned with the formation of the first stars and galaxies and how metal-poor stars can be used to constrain these processes. Complementary abundance measurements in high-redshift gas clouds further help to establish the early chemical evolution of the Universe. The data appear consistent with the existence of two distinct channels of star formation at the earliest times.

  16. Deep underground disposal of radioactive wastes: Near field effects

    International Nuclear Information System (INIS)

    This report reviews the important near-field effects of the disposal of wastes in deep rock formations. The basic characteristics of waste form, container and package, buffer and backfill materials and potential host-rock types are discussed from the perspective of the performance requirements of the total repository system. Effects of waste emplacement on the separate system components and on the system as a whole are discussed. The effects include interactions between groundwater and brines and the other system components, thermal and thermo-mechanical effects, and chemical and geochemical reactions. Special consideration is given to the radiation field that exists in proximity to the waste containers and also to the coupled effects of different phenomena

  17. Near-field photocurrent nanoscopy on bare and encapsulated graphene

    Science.gov (United States)

    Woessner, Achim; Alonso-González, Pablo; Lundeberg, Mark B.; Gao, Yuanda; Barrios-Vargas, Jose E.; Navickaite, Gabriele; Ma, Qiong; Janner, Davide; Watanabe, Kenji; Cummings, Aron W.; Taniguchi, Takashi; Pruneri, Valerio; Roche, Stephan; Jarillo-Herrero, Pablo; Hone, James; Hillenbrand, Rainer; Koppens, Frank H. L.

    2016-02-01

    Optoelectronic devices utilizing graphene have demonstrated unique capabilities and performances beyond state-of-the-art technologies. However, requirements in terms of device quality and uniformity are demanding. A major roadblock towards high-performance devices are nanoscale variations of the graphene device properties, impacting their macroscopic behaviour. Here we present and apply non-invasive optoelectronic nanoscopy to measure the optical and electronic properties of graphene devices locally. This is achieved by combining scanning near-field infrared nanoscopy with electrical read-out, allowing infrared photocurrent mapping at length scales of tens of nanometres. Using this technique, we study the impact of edges and grain boundaries on the spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can readily be applied to encapsulated graphene devices. We observe charge build-up near the edges and demonstrate a solution to this issue.

  18. Scanning near field microwave microscopy based on an active resonator

    Science.gov (United States)

    Qureshi, Naser; Kolokoltsev, Oleg; Ordonez-Romero, Cesar Leonardo

    2014-03-01

    A large number of recent implementations of near field scanning microwave microscopy (NFSMM) have been based on the perturbation of a resonant cavity connected to a sharp scanning probe. In this work we present results from an alternative approach: the perturbation of a microwave source connected to a scanning tip. Based on a yittrium iron garnet (YIG) cavity ring resonator this scanning probe system has a quality factor greater than 106, which allows us to detect very small frequency shifts, which translates to a very high sensitivity in sample impedance measurements. Using a selection of representative semiconductor, metal and biological samples we show how this approach leads to unusually high sensitivity and spatial resolution. Work supported by a grant from PAPIIT, UNAM 104513.

  19. Near field radiative heat transfer between two nonlocal dielectrics

    CERN Document Server

    Singer, F; Joulain, Karl

    2015-01-01

    We explore in the present work the near-field radiative heat transfer between two semi-infinite parallel nonlocal dielectric planes by means of fluctuational electrodynamics. We use atheory for the nonlocal dielectric permittivityfunction proposed byHalevi and Fuchs. This theory has the advantage to includedifferent models performed in the literature. According to this theory, the nonlocal dielectric function is described by a Lorenz-Drude like single oscillator model, in which the spatial dispersion effects are represented by an additional term depending on the square of the total wavevector k. The theory takes into account the scattering of the electromagneticexcitation at the surface of the dielectric material, which leads to the need of additional boundary conditions in order to solve Maxwell's equations and treat the electromagnetic transmission problem. The additional boundary conditions appear as additional surface scattering parameters in the expressions of the surface impedances. It is shown that the...

  20. Eavesdropping near-field contactless payments: a quantitative analysis

    Directory of Open Access Journals (Sweden)

    Thomas P. Diakos

    2013-10-01

    Full Text Available This paper presents an assessment of how successful an eavesdropping attack on a contactless payment transaction can be in terms of bit and frame error rates, using an easily concealable antenna and low-cost electronics. Potential success of an eavesdropping attack largely depends on the correct recovery of the data frames used in the ISO 14443 standard. A near-field communication inductive loop antenna was used to emulate an ISO 14443 transmission. For eavesdropping, an identical inductive loop antenna as well as a shopping trolley modified to act like an antenna were used. The authors present and analyse frame error rates obtained with the authors equipment over a range of distances, up to 100 cm, well above the official maximum operating distance depending on the magnetic field strength.

  1. Approaches to eliminate near field artifact of MURA

    Institute of Scientific and Technical Information of China (English)

    WANG Ren-Song; RONG Jun-Yan; WEI Long

    2008-01-01

    Since the coded aperture technique has been successfully applied on X-ray imaging space telescopes, attentions of its development have also been cast on the application in medical imaging, for it has a very tempting quality to greatly enhance the detection sensitivity without gravely lowering the spacial resolution. But when the coded aperture technique is applied to image a nearby object, the so called "near-field artifact"comes up, that is, the reconstructed image has a sort of distortion. Among types of coded apertures the MURA (Modified Uniformly Redundant Array) is one of the most discussed. Roberto Arrcosi came up with the solution to remove the artifacts utilizing mask and antimask. In this article we present two ways to eliminate the second order aberration based on his work.

  2. Directional generation of graphene plasmons by near field interference.

    Science.gov (United States)

    Wang, Lei; Cai, Wei; Zhang, Xinzheng; Xu, Jingjun; Luo, Yongsong

    2016-08-22

    The highly unidirectional excitation of graphene plasmons (GPs) through near-field interference of orthogonally polarized dipoles is investigated. The preferred excitation direction of GPs by a circularly polarized dipole can be simply understood with the angular momentum conservation law. Moreover, the propagation direction of GPs can be switched not only by changing the phase difference between dipoles, but also by placing the z-polarized dipole to its image position, whereas the handedness of the background field remains the same. The unidirectional excitation of GPs can be extended into arc graphene surface as well. Furthermore, our proposal on directional generation of GPs can be realized in a semiconductor nanowire/graphene system, where a semiconductor nanowire can mimic a circularly polarized dipole when illuminated by two orthogonally polarized plane waves. PMID:27557254

  3. INVERSE MEDIUM SCATTERING PROBLEMS IN NEAR-FIELD OPTICS

    Institute of Scientific and Technical Information of China (English)

    Gang Bao; Peijun Li

    2007-01-01

    A regularized recursive linearization method is developed for a two-dimensional inverse medium scattering problem that arises in near-field optics, which reconstructs the scatterer of an inhomogeneous medium deposited on a homogeneous substrate from data accessible through photon scanning tunneling microscopy experiments. In addition to the ill-posedness of the inverse scattering problems, two difficulties arise from the layered background medium and limited aperture data. Based on multiple frequency scattering data, the method starts from the Born approximation corresponding to the weak scattering at a low frequency, each update is obtained via recursive linearization with respect to the wavenumber by solving one forward problem and one adjoint problem of the Helmholtz equation. Numerical experiments are included to illustrate the feasibility of the proposed method.

  4. Mapping Nanoscale Electromagnetic Near-Field Distributions Using Optical Forces

    CERN Document Server

    Huang, Fei; Mardy, Zahra; Burdett, Jonathan; Wickramasinghe, H Kumar

    2014-01-01

    We demonstrate the application of Atomic Force Microscopy (AFM) based optical force microscopy to map the optical near-fields with nanometer resolution, limited only by the AFM probe geometry. We map the electric field distributions of tightly focused laser beams with different polarizations and show that the experimentally measured data agrees well with the theoretical predictions from a dipole-dipole interaction model, thereby validating our approach. We further validate the proposed technique by evaluating the optical electric field scattered by a spherical nanoparticle by measuring the optical forces between the nanoparticle and gold coated AFM probe. The technique allows for wavelength independent, background free, thermal noise limited mechanical imaging of optical phenomenon with sensitivity limited by AFM performance. Optical forces due to both electric and magnetic dipole-dipole interactions can be measured using this technique.

  5. Study of Near Field Communication Technology in University Scenarios

    Science.gov (United States)

    Ruiz, Irene Luque; Miraz, Guillermo Matas; Gómez-Nieto, Miguel Ángel

    2009-08-01

    In this paper we present an introduction to the possibilities of NFC (Near Field Communication) technology in the University environment. NFC is the key for the development of interactive systems where "intelligent" objects interact with the user just only by touching the objects with a NFC device. We support that a University environment with active objects dispatching information and services to the users (students and teachers) can introduce an appropriate environment for the fulfillment of the new Educational European directives. Here, we briefly describe some of the possibilities of the NFC technology and we include an example of the use of NFC through a Smart Poster for a scenario where a Department directory is considered.

  6. Use of pressure insoles to calculate the complete ground reaction forces

    NARCIS (Netherlands)

    Forner Cordero, A.; Koopman, H.F.J.M.; Helm, van der F.C.T.

    2004-01-01

    A method to calculate the complete ground reaction force (GRF) components from the vertical GRF measured with pressure insoles is presented and validated. With this approach it is possible to measure several consecutive steps without any constraint on foot placement and compute a standard inverse dy

  7. Electronic and Mechanical Properties of Tetragonal Nb2Al Under High Pressure: First-Principles Calculations

    Science.gov (United States)

    Jiao, Zhen; Liu, Qi-Jun; Liu, Fu-Sheng; Wang, Wen-Peng; Wang, Yi-Gao; Li, Yong; Liu, Zheng-Tang

    2016-04-01

    We have investigated the structure, density of states, mechanical stability, elastic properties, and Debye temperature of tetragonal Nb2Al under high pressure using the generalized gradient approximation WC (GGA-WC) functional within density functional theory (DFT). Our obtained lattice constants were in good agreement with the reported experimental and theoretical data at zero pressure. The volume decreased with the increasing pressure. The effects of pressure on the electronic properties have been discussed. The elastic constants under pressure have been calculated, which all satisfied the stability criterion, meaning that tetragonal Nb2Al was mechanical stability from 0 to 100 GPa. Then, the mechanical properties including bulk modulus B, shear modulus G, Young's modulus E, G/B, and Poisson's ratio ν under pressure were determined using the Voigt-Reuss-Hill method. The G/B value suggested that tetragonal Nb2Al exhibited ductile behavior under pressure. Poisson's ratio indicated that the interatomic forces in tetragonal Nb2Al were mainly central forces. Finally, the transverse, longitudinal, and average sound velocities and Debye temperature of tetragonal Nb2Al under pressure have been estimated.

  8. Laser-induced cantilever behaviour in apertureless scanning near-field optical microscopes

    International Nuclear Information System (INIS)

    The laser-induced deformation of a typical commercial cantilever commonly used for scanning near-field optical microscopes was investigated by means of a software package based on the finite element method. The thermo-mechanical behaviour of such a cantilever whose tip was irradiated by a laser beam was calculated in the temperature regime between room temperature and 850 K. The spatial tip displacement was simulated at timescales <0.1 ms, since feedback-based constant force measurements exhibit reaction times in this range. It could be shown that in addition to former tip-based thermal expansion calculations the cantilever deformation is already significant at moderate temperatures, particularly when a reflective coating is present. The experimental and calculated results suggest that tip scanning in cantilever-based scanning probe microscopes for laser-based surface modification applications should be performed in thermal equilibrium. (paper)

  9. High-pressure elastic properties of cubic Ir2P from ab initio calculations

    Science.gov (United States)

    Sun, Xiao-Wei; Bioud, Nadhira; Fu, Zhi-Jian; Wei, Xiao-Ping; Song, Ting; Li, Zheng-Wei

    2016-10-01

    A study of the high-pressure elastic properties of new synthetic Ir2P in the anti-fluorite structure is conducted using ab initio calculations based on density functional theory. The elastic constants C11, C12 and C44 for the cubic Ir2P are obtained by the stress-strain method and the elastic stability calculations under pressure indicate that it is stable at least 100 GPa. Additionally, the electronic density of states, the aggregate elastic moduli, that is bulk modulus, shear modulus, and Young's modulus along with the Debye temperature, Poisson's ratio, and elastic anisotropy factor are all successfully obtained. Moreover, the pressure dependence of the longitudinal and shear wave velocities in three different directions [100], [110], and [111] for Ir2P are also predicted for the first time.

  10. AB INITIO CALCULATIONS OF ELASTIC CONSTANTS OF BCC V-NB SYSTEM AT HIGH PRESSURES

    Energy Technology Data Exchange (ETDEWEB)

    Landa, A; Klepeis, J; Soderlind, P; Naumov, I; Velikokhatnyi, O; Vitos, L; Ruban, A

    2005-05-02

    First-principles total energy calculation based on the exact muffin-tin orbital and full potential linear muffin-tin orbital methods were used to calculate the equation of state and shear elastic constants of bcc V, Nb, and the V{sub 95}Nb{sub 05} disordered alloy as a function of pressure up to 6 Mbar. We found a mechanical instability in C{sub 44} and a corresponding softening in C at pressures {approx} 2 Mbar for V. Both shear elastic constants show softening at pressures {approx} 0.5 Mbar for Nb. Substitution of 5 at. % of V with Nb removes the instability of V with respect to trigonal distortions in the vicinity of 2 Mbar pressure, but still leaves the softening of C{sub 44} in this pressure region. We argue that the pressure induced shear instability (softening) of V (Nb) originates from the electronic system and can be explained by a combination of the Fermi surface nesting, electronic topological transition, and band Jahn-Teller effect.

  11. On sparse reconstructions in near-field acoustic holography using the method of superposition

    CERN Document Server

    Abusag, Nadia M

    2016-01-01

    The method of superposition is proposed in combination with a sparse $\\ell_1$ optimisation algorithm with the aim of finding a sparse basis to accurately reconstruct the structural vibrations of a radiating object from a set of acoustic pressure values on a conformal surface in the near-field. The nature of the reconstructions generated by the method differs fundamentally from those generated via standard Tikhonov regularisation in terms of the level of sparsity in the distribution of charge strengths specifying the basis. In many cases, the $\\ell_1$ optimisation leads to a solution basis whose size is only a small fraction of the total number of measured data points. The effects of changing the wavenumber, the internal source surface and the (noisy) acoustic pressure data in general will all be studied with reference to a numerical study on a cuboid of similar dimensions to a typical loudspeaker cabinet. The development of sparse and accurate reconstructions has a number of advantageous consequences includin...

  12. Modeling of coastal effluent transport: an approach to linking far-field and near-field models

    Institute of Scientific and Technical Information of China (English)

    YANG Zhaoqing; KHANGAOKAR Tarang

    2008-01-01

    One of the challenges in effluent transport modeling in coastal tidal environments is the proper specification of initial dilution in connection with the far-field transport phenomena. An approach of external linkage of far-field and near-field effluent transport models is presented, and applied to simulating the effluent transport in the Port Angeles Harbor, Washington in the Strait of Juan de Fuea. A near-field plume model was used to calculate the effluent initial dilution and a three-dimensional (3-D) hydrodynamic model was developed to simulate the tidal circulation and far-field effluent transport in the Port Angeles Harbor. The hydrodynamic model was driven by tides and surface winds. Observed water surface elevation and velocity data were used to calibrate the model over a period covering the neap-spring tidal cycle. The model was also validated with observed surface drogue trajectory data. The model successfully reproduced the tidal dynamics in the study area and good agreements between model results and observed data were obtained. It is demonstrated that the linkage between the near-field and far-field models in effluent transport modeling can be achieved through iteratively adjusting the model grid sizes such that the dilution ratio and effluent concentration in the circulation model grid cell match the concentration calculated by the near-field plume model.

  13. Near-field chemistry of the spent nuclear fuel repository; Kemialliset vuorovaikutukset kaeytetyn ydinpolttoaineen loppusijoitustilan laehialueella

    Energy Technology Data Exchange (ETDEWEB)

    Kumpulainen, H.; Lehikoinen, J.; Muurinen, A.; Ollila, K. [VTT Chemical Technology, Espoo (Finland). Industrial Physics

    1998-07-01

    Factors affecting near-field chemistry of the spent nuclear fuel repository as well as the involved mutual interactions are described on the basis of literature. The most important processes in the near-field (spent-fuel, canister and bentonite) are presented. The related examples on near-field chemistry models shed light on the extensive problematics of near-field chemistry. (authors) 80 refs.

  14. Near-field radiative heat transfer between arbitrarily shaped objects and a surface

    Science.gov (United States)

    Edalatpour, Sheila; Francoeur, Mathieu

    2016-07-01

    A fluctuational electrodynamics-based formalism for calculating near-field radiative heat transfer between objects of arbitrary size and shape and an infinite surface is presented. The surface interactions are treated analytically via Sommerfeld's theory of electric dipole radiation above an infinite plane. The volume integral equation for the electric field is discretized using the thermal discrete dipole approximation (T-DDA). The framework is verified against exact results in the sphere-surface configuration and is applied to analyze near-field radiative heat transfer between a complex-shaped probe and an infinite plane, both made of silica. It is found that, when the probe tip size is approximately equal to or smaller than the gap d separating the probe and the surface, coupled localized surface phonon (LSPh)-surface phonon-polariton (SPhP) mediated heat transfer occurs. In this regime, the net spectral heat rate exhibits four resonant modes due to LSPhs along the minor axis of the probe, while the net total heat rate in the near field follows a d-0.3 power law. Conversely, when the probe tip size is much larger than the separation gap d , heat transfer is mediated by SPhPs, resulting in two resonant modes in the net spectral heat rate, corresponding to those of a single emitting silica surface, while the net total heat rate approaches a d-2 power law. It is also demonstrated that a complex-shaped probe can be approximated by a prolate spheroidal electric dipole when the thermal wavelength is larger than the major axis of the spheroidal dipole and when the separation gap d is much larger than the radius of curvature of the dipole tip facing the surface.

  15. Methodology for Calculation of Pressure Impulse Distribution at Gas-Impulse Regeneration of Water Well Filters

    Directory of Open Access Journals (Sweden)

    V. V. Ivashechkin

    2010-01-01

    Full Text Available The paper considers a mathematical model for process of pressure impulse distribution in a water well which appear as a result of underwater gas explosions in cylindrical and spherical explosive chambers with elastic shells and in a rigid cylindrical chamber which is open from the bottom. The proposed calculation methodology developed on the basis of the mathematical model makes it possible to determine pressure in the impulse on a filter wall and at any point of a water well pre-filter zone. 

  16. Recommended Practice for Pressure Measurements and Calculation of Effective Pumping Speeds During Electric Propulsion Testing

    Science.gov (United States)

    Dankanich, John W.; Walker, Mitchell; Swiatek, Michael W.; Yim, John T.

    2013-01-01

    The electric propulsion community has been implored to establish and implement a set of universally applicable test standards during the research, development, and qualification of electric propulsion systems. Variability between facility-to-facility and more importantly ground-to-flight performance can result in large margins in application or aversion to mission infusion. Performance measurements and life testing under appropriate conditions can be costly and lengthy. Measurement practices must be consistent, accurate, and repeatable. Additionally, the measurements must be universally transportable across facilities throughout the development, qualification, spacecraft integration, and on-orbit performance. A recommended practice for making pressure measurements, pressure diagnostics, and calculating effective pumping speeds with justification is presented.

  17. Measurement of High Reynolds Number Near-Field Turbulent Sphere Wakes under Stratified Conditions

    Science.gov (United States)

    Kalumuck, Kenneth; Brandt, Alan; Decker, Kirk; Shipley, Kara

    2015-11-01

    To characterize the near-field of a stratified wake at Reynolds numbers, Re = 2 x 105 - 106, experiments were conducted with a large diameter (0.5 m) sphere towed through a thermally stratified fresh water lake. Stratification produced BV frequencies, N, up to 0.07/s (42 cph) resulting in Froude numbers F = U/ND >= 15. The submerged sphere and associated instrumentation including two Acoustic Doppler Velocimeters (ADVs) and an array of fast response thermistors were affixed to a common frame towed over a range of speeds. Three components of the instantaneous wake velocities were obtained simultaneously at two cross-wake locations with the ADVs while density fluctuations were inferred from temperature measurements made by the thermistors. These measurements were used to determine the mean, rms, and spectra of all three components of the turbulent velocity field and density fluctuations at multiple locations. The turbulence power spectra follow the expected -5/3 slope with wavenumber. Existing stratified near-field wake data for spheres are for Re =104 and less, and only a very limited set of data under unstratified conditions exists at these large values of Re. Those data are primarily measurements of the sphere drag, surface pressure distribution, and separation rather than in wake turbulence. Advances in CFD modeling have enabled simulations at these high Reynolds numbers without quantitative data available for validation. Sponsored by ONR Turbulence and Wakes program.

  18. Photocurrent mapping of near-field optical antenna resonances

    KAUST Repository

    Barnard, Edward S.

    2011-08-21

    An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data. Here, we demonstrate a photodetector platform that uses a silicon-on-insulator substrate to spectrally and spatially map the absolute values of enhanced fields near any type of optical antenna by transducing local electric fields into photocurrent. We are able to quantify the resonant optical and materials properties of nanoscale (∼50nm) and wavelength-scale (∼1μm) metallic antennas as well as high-refractive-index semiconductor antennas. The data agree well with light-scattering measurements, full-field simulations and intuitive resonator models. © 2011 Macmillan Publishers Limited. All rights reserved.

  19. Entropic and Near-Field Improvements of Thermoradiative Cells

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan K.; Liao, Bolin; Huang, Yi; Boriskina, Svetlana V.; Chen, Gang

    2016-10-01

    A p-n junction maintained at above ambient temperature can work as a heat engine, converting some of the supplied heat into electricity and rejecting entropy by interband emission. Such thermoradiative cells have potential to harvest low-grade heat into electricity. By analyzing the entropy content of different spectral components of thermal radiation, we identify an approach to increase the efficiency of thermoradiative cells via spectrally selecting long-wavelength photons for radiative exchange. Furthermore, we predict that the near-field photon extraction by coupling photons generated from interband electronic transition to phonon polariton modes on the surface of a heat sink can increase the conversion efficiency as well as the power generation density, providing more opportunities to efficiently utilize terrestrial emission for clean energy. An ideal InSb thermoradiative cell can achieve a maximum efficiency and power density up to 20.4% and 327 Wm‑2, respectively, between a hot source at 500 K and a cold sink at 300 K. However, sub-bandgap and non-radiative losses will significantly degrade the cell performance.

  20. Near-Field Cosmology with Local Group Dwarf Spheroidals

    CERN Document Server

    Grebel, E K

    2005-01-01

    The Local Group offers an excellent laboratory for near-field cosmology by permitting us to use the resolved stellar content of its constituent galaxies as probes of galaxy formation and evolution, which in turn is an important means for testing cosmological models of hierarchical structure formation. In this review, we discuss the the least massive, yet most numerous type of galaxy in the Local Group, the dwarf spheroidal galaxies, and compare their properties to cosmological predictions. In particular, we point out problems found with a simple building block scenario and with effects expected from reionization. We show that the star formation histories of dSphs are inconsistent with the predicted cessation of star formation after reionization; instead, extended star formation episodes are observed. The Galactic dSphs contain in part prominent intermediate-age populations, whereas the Galactic halo does not. Conversely, the M31 dSphs are almost entirely old, while the M31 halo contains a substantial intermed...

  1. Application of Near Field Communication Technology for Mobile Airline Ticketing

    Directory of Open Access Journals (Sweden)

    Wayan Suparta

    2012-01-01

    Full Text Available Problem statement: Near Field Communication (NFC technology opens up exciting new usage scenarios for mobile devices based platform. Users of NFC-enabled devices can simply point or touch their devices to other NFC-enabled elements in the environment to communicate with them (‘contactless’, making application and data usage easy and convenient. Approach: The study describes the characteristics and advantages of NFC technology offers for the development of mobile airline ticketing. This scenario describes the potential to overcome the conventional systems that are not gated and use study tickets. In such a system, today a transport application can be loaded on a NFC-enabled phone. To study such a case, Yogyakarta International Airport was taken as an example for a discussion. Results: NFC technology which consisting of three modes of operation and with international standardization can be applied as contactless to simplicity transactions, content delivery and information sharing on a mobile based platform. Conclusion: The idea of NFC application for mobile airline ticketing has been discussed for Yogyakarta International Airport."

  2. 3D manipulation with a scanning near field optical nanotweezers

    CERN Document Server

    Berthelot, J; Juan, M L; Kreuzer, M P; Renger, J; Quidant, R

    2013-01-01

    Recent advances in Nanotechnologies have prompted the need for tools to accurately and non-invasively manipulate individual nano-objects. Among possible strategies, optical forces have been foreseen to provide researchers with nano-optical tweezers capable to trap a specimen and move it in 3D. In practice though, the combination of weak optical forces involved and photothermal issues have thus far prevented their experimental realization. Here, we demonstrate first 3D optical manipulation of single 50 nm dielectric objects with near field nano-tweezers. The nano-optical trap is built by engineering a bowtie plasmonic aperture at the extremity of a tapered metal-coated optical fiber. Both the trapping operation and monitoring are performed through the optical fiber making these nano-tweezers totally autonomous and free of bulky optical elements. The achieved trapping performances allow for the trapped specimen to be moved over tens of micrometers during several minutes with very low in-trap intensities. This n...

  3. A Calculation Approach to Elastic Constants of Crystallines at High Pressure and Finite Temperature

    Institute of Scientific and Technical Information of China (English)

    向士凯; 蔡灵仓; 张林; 经福谦

    2002-01-01

    Elastic constants of Na and Li metals are calculated successfully for temperatures up to 350K and pressures up to 30 GPa using a scheme without involving any adjustable parameter. Elastic constants are assumed to depend only on an effective pair potential that is only determined by the average interatomic distance. Temperature has an effect on elastic constants by way of charging the equilibrium. The elastic constants can be obtained by fitting the relationship between total energy and strain tensor using the new set of lattice parameters obtained by calculating displacement of atoms at the finite temperature and at a fixed pressure. The relationship between the effective pair potential and the interatomic distance is fitted by using a series of data of cohesive energy corresponding to lattice parameters.

  4. Numerical calculations of pressure oscillations in a side-dump ramjet engine

    OpenAIRE

    Yang, V.; Culick, F. E. C.

    1984-01-01

    Pressure oscillations in a side-dump ramjet engine have been studied, using a one-dimensional numerical analysis. The engine is treated in two parts; the inlet section, including a region of two-phase flow downstream of fuel injection, and a dump combustor. Each region is treated separately and matched with the other. Following calculation of the mean flow field, the oscillatory characteristics of the engine are determined by its reponse to a disturbance imposed on the...

  5. First-principles calculations of structure and high pressure phase transition in gallium nitride

    Institute of Scientific and Technical Information of China (English)

    Tan Li-Na; Hu Cui-E; Yu Bai-Ru; Chen Xiang-Rong

    2007-01-01

    The phase transitions of semiconductor GaN from the Wurtzite (WZ) structure and the zinc-blende (ZB) structure to the rocksalt (RS) structure are investigated by using the first-principles plane-wave pseudopotential density functional method combined with the ultrasoft pseudopotential scheme in the generalized gradient approximation (GGA)correction. It is found that the phase transitions from the WZ structure and the ZB structure to the RS structure occur at pressures of 46.1 GPa and 45.2 GPa, respectively. The lattice parameters, bulk moduli and their pressure derivatives of these structures of GaN are also calculated. Our results are consistent with available experimental and other theoretical results. The dependence of the normalized formula-unit volume V/Vo on pressure P is also successfully obtained.

  6. An ab-initio coupled mode theory for near field radiative thermal transfer.

    Science.gov (United States)

    Chalabi, Hamidreza; Hasman, Erez; Brongersma, Mark L

    2014-12-01

    We investigate the thermal transfer between finite-thickness planar slabs which support surface phonon polariton modes (SPhPs). The thickness-dependent dispersion of SPhPs in such layered materials provides a unique opportunity to manipulate and enhance the near field thermal transfer. The key accomplishment of this paper is the development of an ab-initio coupled mode theory that accurately describes all of its thermal transfer properties. We illustrate how the coupled mode parameters can be obtained in a direct fashion from the dispersion relation of the relevant modes of the system. This is illustrated for the specific case of a semi-infinite SiC substrate placed in close proximity to a thin slab of SiC. This is a system that exhibits rich physics in terms of its thermal transfer properties, despite the seemingly simple geometry. This includes a universal scaling behavior of the thermal conductance with the slab thickness and spacing. The work highlights and further increases the value of coupled mode theories in rapidly calculating and intuitively understanding near-field transfer. PMID:25606933

  7. Strains of scattering of near-field of a point source

    Indian Academy of Sciences (India)

    M D Sharma

    2004-06-01

    Three dimensional scattering of near-field is studied for dilatation and rotation in the time domain. The perturbation method is applied to solve the equation of motion for the first order scattering from a weak inhomogeneity in an otherwise homogeneous medium. The inhomogeneity is assumed close enough to the point source so that the near-field intermediate wave is dominating over the far-field spherical and pulses. The integral expressions are derived to relate dilatation and rotation of scattering to the radial fluctuations of velocities and density in the inhomogeneity. These integrals are solved to calculate the strains of scattering from (a part of) an inhomogeneous spherical shell of arbitrary curvature. Variable curvature may allow the shape of inhomogeneity volume element to change uniformly from spherical to rectangular. Rotation of scattering from a spherical shell is independent of wave velocity inhomogeneity. Dilatation of scattering does not involve wave velocity inhomogeneity but its gradient. The back scattering results are obtained as a special case. Strains are computed numerically, for hypothetical models to study the effects of various parameters viz., velocity inhomogeneity, distance of source from inhomogeneity and from receiver, and thickness of inhomogeneity. The curvature of the spherical shell is varied to study the effects of the shape of inhomogeneous volume element on scattering.

  8. Near-field nonuniformities in angularly multiplexed KrF fusion lasers with induced spatial incoherence

    Science.gov (United States)

    Lehmberg, Robert H.; Chan, Yung

    2005-05-01

    Induced spatial incoherence (ISI) has been proposed for KrF laser drivers to achieve the high degree of spatial beam uniformity required for direct-drive inertial confinement fusion. Although ISI provides ultrasmooth illumination at the far field of the laser, where the target is located, it can still allow the beams in the quasi-near field to develop a time-averaged spatial structure. This speckle, which arises primarily from random-phase aberration, builds up as the laser beams propagate away from the pupil plane located at the final amplifier stage; it is distinct from any structure imposed by gain nonuniformities in the amplifiers. Because of the spatial incoherence, the speckle is significantly smaller than that experienced by coherent beams. Nevertheless, it remains a damage issue, especially for the long beam delay paths required in angularly multiplexed KrF lasers. We develop a novel algorithm for calculating the time-integrated intensities; compare simulations and measurements of the near-field speckle in the Nike KrF laser; and explore options, such as aberration reduction and optical relaying, for controlling the problem in future angularly multiplexed KrF drivers. © Optical Society of America

  9. Near-field radiative heat transfer between arbitrarily-shaped objects and a surface

    CERN Document Server

    Edalatpour, Sheila

    2016-01-01

    A fluctuational electrodynamics-based formalism for calculating near-field radiative heat transfer between objects of arbitrary size and shape and an infinite surface is presented. The surface interactions are treated analytically via Sommerfeld's theory of electric dipole radiation above an infinite plane. The volume integral equation for the electric field is discretized using the thermal discrete dipole approximation (T-DDA). The framework is verified against exact results in the sphere-surface configuration, and is applied to analyze near-field radiative heat transfer between a complex-shaped probe and an infinite plane both made of silica. It is found that when the probe tip size is approximately equal to or smaller than the gap d separating the probe and the surface, coupled localized surface phonon (LSPh)-surface phonon-polariton (SPhP) mediated heat transfer occurs. In this regime, the net spectral heat rate exhibits four resonant modes due to LSPhs along the minor axis of the probe while the net tota...

  10. Development of Spherical Near Field Model for Geological Radioactive Waste Repository

    International Nuclear Information System (INIS)

    Modeling for geological radioactive waste repository can be divided into 3 parts. They are near field modeling related to engineered barrier, far field modeling related to natural barrier and biosphere modeling. In order to make the general application for safety assessment of geological waste repository, spherical geometry near field model has been developed. This model can be used quite extensively when users calculate equivalent spherical geometry for specific engineered barrier like equivalent waste radius, equivalent barrier radius and etc. Only diffusion was considered for general purpose but advection part can be updated. Goldsim and Goldsim Radionuclide Transport (RT) module were chosen and used as developing tool for the flexible modeling. Developer can freely make their own model with developer friendly graphic interface by using Goldsim. Furthermore, model with user friendly graphic interface can be developed by using Goldsim Dashboard Authoring module. The model has been validated by comparing the result with that of another model, inserting similar inputs and conditions. The model has been proved to be reasonably operating from the comparison result by validation process. Cylindrical model can be developed as a further work based on the knowledge and experience from this research

  11. Higher-order elastic constants and megabar pressure effects of bcc tungsten: Ab initio calculations

    Science.gov (United States)

    Vekilov, Yu. Kh.; Krasilnikov, O. M.; Lugovskoy, A. V.; Lozovik, Yu. E.

    2016-09-01

    The general method for the calculation of n th (n ≥2 ) order elastic constants of the loaded crystal is given in the framework of the nonlinear elasticity theory. For the crystals of cubic symmetry under hydrostatic compression, the two schemes of calculation of the elastic constants of second, third, and fourth order from energy-finite strain relations and stress-finite strain relations are implemented. Both techniques are applied for the calculation of elastic constants of orders from second to fourth to the bcc phase of tungsten at a 0-600 GPa pressure range. The energy and stress at the various pressures and deformations are obtained ab initio in the framework of projector augmented wave+generalized gradient approximation (PAW+GGA) method, as implemented in Vienna Ab initio Simulation Package (VASP) code. Using the obtained results, we found the pressure dependence of Grüneisen parameters for long-wave acoustic modes in this interval. The Lamé constants of second and third order were estimated for polycrystalline tungsten. The proposed method is applicable for crystals with arbitrary symmetry.

  12. Modeling the Optical Response to a Near-Field Probe Tip from a Generalized Multilayer Thin Film

    Science.gov (United States)

    Lawrence, A. J.

    The contrast mechanism in Kerr imaging is the apparent angle through which the plane of polarization is rotated upon reflection from a magnetic surface. This can be calculated for a well characterized surface given the polarization state of the incident light. As in traditional optical microscopy, the spatial resolution is limited by diffraction to roughly half the wavelength of the illumination light. The diffraction limit can be circumvented through the use of near-field scanning optical microscopy, in which the illumination source is an evanescent field at the tip of a tapered optical fiber. A novel probe design for near-field optical imaging in reflection mode will be proposed, and experimental work on the development of a near-field Kerr microscope performed up to this point will be presented. The complication in merging these two techniques arises from the complex polarization profile of the evanescent field. This profile can be characterized for a given probe geometry with the use of electromagnetic field modeling software, allowing for subsequent modeling of the polarization profile of the optical response. An algorithm for predicting the optical response to a near-field probe tip from a generalized multilayer thin-film is presented.

  13. The near field acoustic holography technique for cyclostationary sound field and its experimental research

    Institute of Scientific and Technical Information of China (English)

    WAN Quan; JIANG Weikang

    2005-01-01

    One near field acoustic holography (NAH) technique is proposed for analyzing cyclostationary sound field. The signal of this kind of sound field has very serious modulation phenomenon generally, in spectrum of which obvious sidebands exist. It is difficult for the traditional NAH to possess demodulation function, so virtual power of sidebands exists in its hologram. Replacing the Fourier's transform with the second-order cyclic statistics, the proposed NAH technique uses the cyclic spectrum density (CSD) function as reconstructed physical quantity, instead of the spectrum or power spectrum density of sound pressure signal.The CSD function can demodulate cyclostationary signals, which makes no virtual power of sidebands in its hologram. The results of simulation and experiment show that the proposed NAH can extract more information about cyclostationary sound field than traditional NAH, by which sound field can be known more clearly.

  14. Near-Field Characterization of Radial and Axial Blast Waves From a Cylindrical Explosive Charge

    Science.gov (United States)

    McNesby, Kevin; Homan, Barrie

    This paper uses experiment (high speed imaging) and simulation (ALE-3D) to investigate radial and axial blast waves produced by uncased, cylindrical charges of TNT (trinitrotoluene). Recently there has been work reported on predicting secondary blast waves in the explosive mid-field (approximately 1 meter from charge center of mass) for cylindrical charges of RDX (trimethylenetrinitramine)/binder formulations. The work we will present seeks to provide complementary information in the explosive near-field, including the approach to chemical ``freeze out'', for end-detonated, right circular cylinders of TNT. Additionally, this work attempts to retrieve state variables (temperature, pressure, velocities) from high-definition images of the explosive event. Keywords: cylindrical charges, blast, shock waves

  15. Single layer planar near-field acoustic holography for compact sources and a parallel reflector

    Science.gov (United States)

    Zea, Elias; Lopez Arteaga, Ines

    2016-10-01

    We consider the problem of planar near-field acoustic holography (PNAH) and introduce a new reconstruction method that can be used to process single layer pressure measurements performed in the presence of a reflective surface that is parallel to the measurement plane. The method is specially tailored for compact sources, or for problems in which the scattered field due to the source can be neglected. The approach consists in formulating a seismic model (WRW model) in wavenumber-space and employ it for sound source reconstructions. The proposed method is validated with numerical and experimental data, and, although the most accurate results are obtained when an estimate of the surface impedance is known beforehand, we show that it can substantially improve the reconstruction performance with respect to that of free-field PNAH.

  16. Design of Scattering Scanning Near-Field Optical Microscope

    Science.gov (United States)

    Schrecongost, Dustin

    The primary objective of this work is to construct a fully functional scattering type Scanning Near-field Optical Microscope (s-SNOM), and to understand the working mechanisms behind it. An s-SNOM is an instrument made up of two separate instruments working in unison. One instrument is a scanning optical microscope focusing light onto a raster scanning sample surface combined with an interferometer set up. The second instrument is an Atomic Force Microscope (AFM) operating in noncontact mode. The AFM uses a small probe that interacts with the raster scanning sample surface to map out the topography of the of the sample surface. An s-SNOM uses both of these instruments simultaneously by focusing the light of the optical microscope onto the probe of the AFM. This probe acts as a nano-antenna and confines the light allowing for light-matter interaction to be inferred far below the resolution of the diffraction limit of light. This specific s-SNOM system is unique to others by having a controllable environment. It is high vacuum compatible and variable temperature. In addition, it is efficient at collecting scattered light due to the focusing objective being a partial elliptical mirror which collects 360° of light around the major axis. This s-SNOM system will be used for direct imaging of surface plasmons. Intended works are inducing surface plasmons on InSe thin films, and seeing the enhancement effect of introducing Au nano-rods. Also dielectric properties of materials will be interpreted such as the metal to insulator phase transition of NbO2.

  17. LOCA- and ATWS-calculations for homogeneous and heterogeneous advanced pressurized water reactors

    International Nuclear Information System (INIS)

    LOCA and ATWS calculations have been performed for the two KfK reference designs (homogeneous with p/d=1.2 and heterogeneous reactor) of APWR and for a homogeneous reactor with a tighter fuel rod lattice (p/d=1.123) as well as for a reference PWR. The calculations have been performed with the Ispra version of the code RELAP5/Mod.1. New correlations have been introduced in the code to account for the core geometry, which is different from that of a PWR. The results of the calculations show that during the LOCA the fuel rod cladding hot spot temperatures in the seed of the heterogeneous reactor reach values which are about 2500C higher than the corresponding temperatures for a PWR, and that during the ATWS the pressure inside the primary circuit exceeds the maximal allowable pressure in the case of the homogeneous reactor with p/d=1.123. On the basis of the present calculations only the homogeneous reactor with p/d=1.2 appears to be acceptable from a safety point of view. These results need of course experimental confirmation. (orig.)

  18. Designing and calculating the pressure loses for different geometries of CANDU type fuel clusters

    International Nuclear Information System (INIS)

    It is well known that circulation of the coolant through the pressure tube of a CANDU type reactor must ensure, through its flow rate values, the optimal conditions of heat transfer from the fuel clusters towards the heavy water. The flow rate through fuel channels differs from one another (up to 24 kg/s) depending on the fuel element sheath temperature, the latter depending in turn one the channels/clusters positions in the calandria vessel. In these conditions, one of the main problem of design in the CANDU type reactor plants is related to the hydraulic resistance represented by the fuel clusters loading the pressure tube or, in other words, the problem of pressure losses (pressure drops) over the length of the fuel cluster column. More precisely, this hydraulic resistance should not exceed a given value imposed by the performance calculations for the pumps used. A sustained activity of analysing comparatively the different geometry types of the fuel clusters was developed at INR Pitesti, a special attention being paid to their behavior as hydraulic resistances. The paper presents a set of computation programs devoted on one hand to the design of fuel clusters of different types and to an estimating computation of the pressure losses resulting from loading these clusters into a specific fuel channel of the CANDU type reactor, on the other hand. During the presentation of the work, different computing codes will be run for demonstration

  19. Qualification of a Method to Calculate the Irrecoverable Pressure Loss in High Reynolds Number Piping Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sigg, K. C.; Coffield, R. D.

    2002-09-01

    High Reynolds number test data has recently been reported for both single and multiple piping elbow design configurations at earlier ASME Fluid Engineering Division conferences. The data of these studies ranged up to a Reynolds number of 42 x 10[sup]6 which is significantly greater than that used to establish design correlations before the data was available. Many of the accepted design correlations, based on the lower Reynolds number data, date back as much as fifty years. The new data shows that these earlier correlations are extremely conservative for high Reynolds number applications. Based on the recent high Reynolds number information a new recommended method has been developed for calculating irrecoverable pressure loses in piping systems for design considerations such as establishing pump sizing requirements. This paper describes the recommended design approach and additional testing that has been performed as part of the qualification of the method. This qualification testing determined the irrecoverable pressure loss of a piping configuration that would typify a limiting piping section in a complicated piping network, i.e., multiple, tightly coupled, out-of-plane elbows in series under high Reynolds number flow conditions. The overall pressure loss measurements were then compared to predictions, which used the new methodology to assure that conservative estimates for the pressure loss (of the type used for pump sizing) were obtained. The recommended design methodology, the qualification testing and the comparison between the predictions and the test data are presented. A major conclusion of this study is that the recommended method for calculating irrecoverable pressure loss in piping systems is conservative yet significantly lower than predicted by early design correlations that were based on the extrapolation of low Reynolds number test data.

  20. Control of near-field radiative heat transfer via surface phonon-polariton coupling in thin films

    OpenAIRE

    Francoeur, M.; Mengüç, M. Pınar; Vaillon, R.

    2010-01-01

    The possibily of controlling near-field radiative heat transfer via thin films supporting surface phonon-polaritons (SPhPs) is explored. Local density of electromagnetic states (LDOS) within the nanometric gap formed between two silicon carbide (SiC) films and the radiative heat flux exchanged between the thin layers are calculated. Using this information, engineering of desired heat transfer profiles can be obtained, which can be used for the next generation energy harvesting device. Kent...

  1. Mean Blood Pressure Assessment during Post-Exercise: Result from Two Different Methods of Calculation

    Directory of Open Access Journals (Sweden)

    Gianmarco Sainas, Raffaele Milia, Girolamo Palazzolo, Gianfranco Ibba, Elisabetta Marongiu, Silvana Roberto, Virginia Pinna, Giovanna Ghiani, Filippo Tocco, Antonio Crisafulli

    2016-09-01

    Full Text Available At rest the proportion between systolic and diastolic periods of the cardiac cycle is about 1/3 and 2/3 respectively. Therefore, mean blood pressure (MBP is usually calculated with a standard formula (SF as follows: MBP = diastolic blood pressure (DBP + 1/3 [systolic blood pressure (SBP – DBP]. However, during exercise this proportion is lost because of tachycardia, which shortens diastole more than systole. We analysed the difference in MBP calculation between the SF and a corrected formula (CF which takes into account changes in the diastolic and systolic periods caused by exercise-induced tachycardia. Our hypothesis was that the SF potentially induce a systematic error in MBP assessment during recovery after exercise. Ten healthy males underwent two exercise-recovery tests on a cycle-ergometer at mild-moderate and moderate-heavy workloads. Hemodynamics and MBP were monitored for 30 minutes after exercise bouts. The main result was that the SF on average underestimated MBP by –4.1 mmHg with respect to the CF. Moreover, in the period immediately after exercise, when sustained tachycardia occurred, the difference between SF and CF was large (in the order of -20-30 mmHg. Likewise, a systematic error in systemic vascular resistance assessment was present. It was concluded that the SF introduces a substantial error in MBP estimation in the period immediately following effort. This equation should not be used in this situation.

  2. Elastic Properties of Tricalcium Aluminate from High-Pressure Experiments and First-Principles Calculations

    KAUST Repository

    Moon, Juhyuk

    2012-06-04

    The structure and elasticity of tricalcium aluminate (C 3A) have been experimentally and theoretically studied. From high-pressure X-ray diffraction experiments, the bulk modulus of 102(6) and 110(3) GPa were obtained by fitting second- and third-order finite strain equation of state, respectively. First-principles calculations with a generalized gradient approximation gave an isotropic bulk modulus of 102.1 GPa and an isothermal bulk modulus of 106.0 GPa. The static calculations using the exchange-correlation functional show an excellent agreement with the experimental measurements. Based on the agreement, accurate elastic constants and other elastic moduli were computed. The slight difference of behavior at high pressure can be explained by the infiltration of pressure-transmitting silicone oil into structural holes in C 3A. The computed elastic and mechanical properties will be useful in understanding structural and mechanical properties of cementitious materials, particularly with the increasing interest in the advanced applications at the nanoscale. © 2012 The American Ceramic Society.

  3. Calculation of the wall pressure field generated on a group of buildings by an external explosion

    International Nuclear Information System (INIS)

    The aim is to work out a three-dimensional code calculating the over-pressure distribution on any structure when an air shock wave arrives, especially in the case of a geometry providing multiple waves reflection. The computer code ZEPHIR was written under the assumption that the phenomena agree with the acoustic laws. An integral formulation leads infinite three-dimensional problems to a bidimensional one on a surface S limiting the real D. The surface S is discretized with triangular elements and replaced by the polyedron constituted by the mesh. The pressure is calculated at the barycenter of the triangular elements, with interpolation between several time-steps. The ZEPHIR code has been validated at first againt analytical solutions obtained for simple obstacle geometries. Test were performed with models of PWR buildings at a scale of 1/40, a cylinder for the reactor building and a parallelepiped for the fuel building, used adjacent or separated by a gap. Plastic explosive permits to obtain the pressure-time history of a hydrocarbon explosion at that scale. The results are in good agreement with the computation. The code ZEPHIR is characterized by a relatively cheap utilization

  4. Near field scanning optical microscopy of polycrystalline semiconductors

    Science.gov (United States)

    Herndon, Mary Kay

    1999-09-01

    Photovoltaic devices are commonly used for space applications and remote terrestrial power requirements. Polycrystalline solar cell devices often have much lower efficiencies than their crystalline counterparts, but because they can be fabricated much more cheaply, they can still be cost-effective when compared to single crystal devices. The long term goal of this work is to provide information that will lead to higher quality devices with improved cost efficiency. In order to do this, a better understanding of the mechanisms that take place in these materials is needed. The goal of this thesis was to improve our understanding of these devices by adapting a novel characterization technique, Near Field Scanning Optical Microscopy (NSOM), to the study of polycrystalline films. Visible light NSOM is a relatively new technique that allows for optical characterization of materials with resolution beyond the far-field diffraction limit. By using NSOM to study the physical and electrical properties of polycrystalline solar cells, individual grains can be studied and more insight can be gained as to how various properties of the thin films affect the device efficiency. For this research, an NSOM was designed and built to be versatile enough to handle the sorts of samples and measurements required for studying a variety of photovoltaic devices. As a first step, the NSOM was used to characterize single crystal GaAs solar cell devices. Measurements of topography and NSOM-induced photocurrent were obtained simultaneously on cross sections of the material, allowing the p-n junction to be probed. Because the NSOM data could be compared to an expected result, this allowed verification of the new microscope's imaging capabilities and ensured accurate data interpretation. Effects of surface recombination were detected on the cleaved edges. The NSOM was used to characterize surface quality and study the effects of surface passivation treatments. Of the polycrystalline materials

  5. Response of marine composites subjected to near field blast loading

    Science.gov (United States)

    LiVolsi, Frank

    Experimental studies were performed to understand the explosive response of composite panels when exposed to near-field explosive loading in different environments. The panel construction under consideration was an E-glass fiber-reinforced composite laminate infused with vinyl ester resin (Derakane 8084). The panel was layered bi-axially with plain-woven fiber orientations at 0° and 90°. Panel dimensions were approximately 203 mm x 203 mm x 1 mm (8 in x 8 in x 0.04 in). Experiments were carried out with the panel fully clamped in a holding fixture, which was in turn fastened inside a water tank. The fixture was fastened in such a way as to allow for explosive loading experiments in the following environments: water submersion with water backing, water submersion with air backing, and air immersion with air backing. Experiments were performed in room temperature conditions, and additional experiments in the submerged environments were also performed at high and low water temperatures of 40°C and 0°C, respectively. A stereo Digital Image Correlation (DIC) system was employed to capture the full-field dynamic behavior of the panel during the explosive event. Results indicated that the immersion environment contributes significantly to the blast response of the material and to the specimens' appreciable damage characteristics. The water submersion with air backing environment was found to encourage the greatest panel center point deflection and the most significant damage mechanisms around the boundary. The air immersion with air backing environment was found to encourage less center point deflection and exhibited significant impact damage from the explosive capsule. The water submersion with water backing environment encouraged the least panel deflection and minimal interlaminate damage around the panel boundary and center. Water temperature was found to influence the panel center point deflection, but not damage mechanisms. Maximum positive center point

  6. Resonant Spin Wave Excitation by Terahertz Magnetic Near-field Enhanced with Split Ring Resonator

    CERN Document Server

    Mukai, Y; Yamamoto, T; Kageyama, H; Tanaka, K

    2014-01-01

    Excitation of antiferromagnetic spin waves in HoFeO$_{3}$ crystal combined with a split ring resonator (SRR) is studied using terahertz (THz) electromagnetic pulses. The magnetic field in the vicinity of the SRR induced by the incident THz electric field component excites and the Faraday rotation of the polarization of a near-infrared probe pulse directly measures oscillations that correspond to the antiferromagnetic spin resonance mode. The good agreement of the temperature-dependent magnetization dynamics with the calculation using the two-lattice Landau-Lifshitz-Gilbert equation confirms that the spin wave is resonantly excited by the THz magnetic near-field enhanced at the LC resonance frequency of the SRR, which is 20 times stronger than the incident magnetic field.

  7. Near-field properties of a shell nanocylinder pair with gain materials

    Institute of Scientific and Technical Information of China (English)

    Wang Qiao; Wu Shi-Fa; Wang Xiao-Gang

    2012-01-01

    We study the near-field response of a shell nanocylinder pair,with its core filled by gain materials,using a twodimensional finite-difference time-domain method.It is shown that the gain materials in the core of the cylinder can compensate for the intrinsic absorption of the metal shell,leading to local-field enhancement in the gap of the active pair.A linear dependence is found between the field enhancement and the gain coefficient at resonance.The detailed physics is studied by calculating the electrical-field distribution of the shell pair filled with different gain materials.The influence of the gap width and the shell thickness on the interaction of two adjacent active shell cylinders is also investigated.

  8. On the horizontal wobbling of an object levitated by near-field acoustic levitation.

    Science.gov (United States)

    Kim, Cheol-Ho; Ih, Jeong-Guon

    2007-11-01

    A circular planar object can be levitated with several hundreds of microns by ultrasonic near-field acoustic levitation (NFAL). However, when both the sound source and the levitated object are circularly shaped and the center of the levitated object does not coincide with the source center, instability problem often occurs. When this happens, it becomes difficult to pick up or transport the object for the next process. In this study, when the center of the levitated object was offset from the source center, the moving direction of the levitated object was predicted by using the time averaged potential around the levitated object. The wobbling frequency of the levitated object was calculated by analyzing the nonlinear wobbling motion of the object. It was shown that the predicted wobbling frequencies agreed with measured ones well. Finally, a safe zone was suggested to avoid the unstable movement of an object. PMID:17590402

  9. Modeling and experimental study on near-field acoustic levitation by flexural mode.

    Science.gov (United States)

    Liu, Pinkuan; Li, Jin; Ding, Han; Cao, Wenwu

    2009-12-01

    Near-field acoustic levitation (NFAL) has been used in noncontact handling and transportation of small objects to avoid contamination. We have performed a theoretical analysis based on nonuniform vibrating surface to quantify the levitation force produced by the air film and also conducted experimental tests to verify our model. Modal analysis was performed using ANSYS on the flexural plate radiator to obtain its natural frequency of desired mode, which is used to design the measurement system. Then, the levitation force was calculated as a function of levitation distance based on squeeze gas film theory using measured amplitude and phase distributions on the vibrator surface. Compared with previous fluid-structural analyses using a uniform piston motion, our model based on the nonuniform radiating surface of the vibrator is more realistic and fits better with experimentally measured levitation force. PMID:20040404

  10. Real-time target recognition system simulation based on laser near-field detection

    Institute of Scientific and Technical Information of China (English)

    YU Xiao-liang; MA Hui-min; XIAO Jian

    2009-01-01

    This paper constructs a simulation system of near-field laser imaging for 3D grid model of target, provides some methods for the key problems, such as the modeling of target and laser transceiver, the calculation of laser echo power, the imaging algorithms and so on. A target image h'brary is established by a new imaging method in any rendezvous conditions. The four real-time recognition algorithms which are efficient and suitable for hardware implementation are presented at the condi-tions of the image incompleteness, intensive noise and arbitrary attitude of target. The experimental results show that all the four algorithms can independently recognize the target effectively and a better recognition effect is obtained by the integra-tion of four algorithms.

  11. Light Irradiation through Small Particles and Its Applications for Surface Nanostructuring in Near Field

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yi; HONG Ming-Hui; FUH Ying-Hsi Jerry; LU Li; TAN Leng Seow; Luk(y)anchuk B S

    2007-01-01

    We investigate the light scattering through small particles and its applications in nanostructuring, such as nanobumping, nanopatterning and dry laser cleaning. The theoretical calculation based on Mie theory provides an exact solution for sphere cavity resonance and plasmon resonance, which are two mechanisms for dielectric and metallic particles assisted surface nanostructuring in near field. The experimental results indicate that nanobumps on glass surface and subwavelength holes array on silicon surface can be formed without cracks with the self-assembly of 1 μm silica particle mask under laser irradiation. It is also found that the scattering wave by 40 nm gold particles can propagate 200 times away in terms of particle radius as recorded by photoresist under the UV light irradiation. Meanwhile, dry laser cleaning of 40 nm gold particle on silicon wafer is demonstrated at plasmonic resonance frequency. The total cleaning efficiency is estimated to be 80%.

  12. High pressurized CO2 release CFD calculations from onshore pipeline leakages

    Science.gov (United States)

    Herzog, Nicoleta; Gorenz, Paul; Egbers, Christoph

    2013-04-01

    Emissions from high pressurized pipelines can be determined on the basis of hydrodynamical and thermophysical calculations of the escaped fluid. If a rupture occurs when CO2 is onshore transported in liquid form there will be initially a large pressure drop in the pipeline, the pressure will fall until the liquid becomes a mixture of saturated vapor/liquid. In the vicinity of the rupture, liquid CO2 will escape and immediately vaporize and expand, some of the liquid will desublimate into dry ice, which will precipitate onto the ground [1, 2]. The period of time taken for a large amount of carbon dioxide to be discharged would be short. Initially CO2 will escape by pushing the overlying soil upwards at an explosion-like speed. After the pressure in the pipe fell the flow profile of the escaping gas will almost be as described for gaseous material transport. The expansion of carbon dioxide will occur at sonic speed and will continue to do so until the pressure ratio between the CO2 and the ambient air is lower than about 1.9 [3]. As a result of the expansion also the temperature of the escaping gas will fall drastically and a cloud of cold gas will form which is then dispersed and slowly mixed with ambient air. The rate of emptying the pipeline is controlled by the pipe cross-section area and the speed of the escaping gas, or by the pressure difference between the pipeline and the atmosphere. Therefore the mass flow will be largest immediately after the accident with an exponential decay in time. In this study a two-phase model is applied to a high pressurized pipeline through which liquid carbon dioxide flows. A leakage is considered to be at different positions along the pipeline and the release pressure is calculated over several parameter ranges. It is also intended to characterize from hydrodynamical point of view the dispersion of released CO2 in the ambient medium by means of CFD simulations which includes multiphase flow treatment. For that a turbulent two

  13. Model for the calculation of pressure loss through heavy fuel oil transfer pipelines

    Directory of Open Access Journals (Sweden)

    Hector Luis Laurencio-Alfonso,

    2012-10-01

    Full Text Available Considering the limitations of methodologies and empirical correlations in the evaluation of simultaneous effects produced by viscous and mix strength during the transfer of fluids through pipelines, this article presents the functional relationships that describe the pressure variations for the non-Newtonian fuel oil flowrate. The experimental study was conducted based on a characterization of the rheological behavior of fuel oil and modeling for a pseudoplastic behavior. The resulting model describes temperature changes, viscous friction effects and the effects of blending flow layers; which is therefore the basis of calculation for the selection, evaluation and rationalization of transport of heavy fuel oil by pipelines.

  14. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    OpenAIRE

    Xiang Wan; Ben Geng Cai; Yun Bo Li; Tie Jun Cui

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the met...

  15. Review of near-field optics and superlenses for sub-diffraction-limited nano-imaging

    Directory of Open Access Journals (Sweden)

    Wyatt Adams

    2016-10-01

    Full Text Available Near-field optics and superlenses for imaging beyond Abbe’s diffraction limit are reviewed. A comprehensive and contemporary background is given on scanning near-field microscopy and superlensing. Attention is brought to recent research leveraging scanning near-field optical microscopy with superlenses for new nano-imaging capabilities. Future research directions are explored for realizing the goal of low-cost and high-performance sub-diffraction-limited imaging systems.

  16. Calculation and analysis of thermal–hydraulics fluctuations in pressurized water reactors

    International Nuclear Information System (INIS)

    Highlights: • Single-phase thermal–hydraulics noise equations are originally derived in the frequency domain. • The fluctuations of all the coolant parameters are calculated, without any simplifying assumptions. • The radial distribution of the temperature fluctuations in the fuel, gap and cladding are taken into account. • The closed-loop calculations are performed by means of the point kinetics noise theory. • Both the space- and frequency-dependence of the thermal–hydraulics fluctuations are analyzed. - Abstract: Analysis of thermal–hydraulics fluctuations in pressurized water reactors (e.g., local and global temperature or density fluctuations, as well as primary and charging pumps fluctuations) has various applications in calculation or measurement of the core dynamical parameters (temperature or density reactivity coefficients) in addition to thermal–hydraulics surveillance and diagnostics. In this paper, the thermal–hydraulics fluctuations in PWRs are investigated. At first, the single-phase thermal–hydraulics noise equations (in the frequency domain) are originally derived, without any simplifying assumptions. The fluctuations of all the coolant parameters, as well as the radial distribution of the temperature fluctuations in the fuel, gap and cladding are taken into account. Then, the derived governing equations are discretized using the finite volume method (FVM). Based on the discretized equations and the proposed algorithm of solving, a single heated channel noise calculation code (SHC-Noise) is developed, by which the steady-state and fluctuating parameters of PWR fuel assemblies can be calculated. The noise sources include the inlet coolant temperature and velocity fluctuations, in addition to the power density noises. The developed SHC-Noise code is benchmarked in different cases and scenarios. Furthermore, to show the effects of the power feedbacks, the closed-loop calculations are performed by means of the point kinetics noise

  17. Very high-accuracy calibration of radiation pattern and gain of a near-field probe

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Nielsen, Jeppe Majlund; Breinbjerg, Olav

    2014-01-01

    In this paper, very high-accuracy calibration of the radiation pattern and gain of a near-field probe is described. An open-ended waveguide near-field probe has been used in a recent measurement of the C-band Synthetic Aperture Radar (SAR) Antenna Subsystem for the Sentinel 1 mission of the Europ......In this paper, very high-accuracy calibration of the radiation pattern and gain of a near-field probe is described. An open-ended waveguide near-field probe has been used in a recent measurement of the C-band Synthetic Aperture Radar (SAR) Antenna Subsystem for the Sentinel 1 mission...

  18. Polarization resolved imaging with a reflection near-field optical microscope

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Xiao, Mufei; Hvam, Jørn Märcher

    1999-01-01

    Using a rigorous microscopic point-dipole description of probe-sample interactions, we study imaging with a reflection scanning near-field optical microscope. Optical content, topographical artifacts, sensitivity window-i.e., the scale on which near-field optical images represent mainly optical...... configuration is preferable to the cross-linear one, since it ensures more isotropic (in the surface plane) near-field imaging of surface features. The numerical results are supported with experimental near-field images obtained by using a reflection microscope with an uncoated fiber tip....

  19. Super-Resolution Imaging on Microfluidic Super-Resolution Near-Field Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Pei; TANG Lin; ZHANG Dou-Guo; LU Yong-Hua; JIAO Xiao-Jin; XIE Jian-Ping; MING Hai

    2005-01-01

    @@ We present a new concept of the microfluidic super-resolution near-field structure (MSRENS) based on a microfluidic structure and a super-resolution near-field structure. The near-field distance control, "nano-probe"and scanning can be realized simultaneously using the MSRENS, which is similar to a near-field scanning optical microscope. The design and simulation results are presented. Numerical simulation has demonstrated that the MSRENS with spatial resolution beyond the diffraction limit could be applicable in chemistry, biologics, and many other fields.

  20. k-space Imaging of the Eigenmodes of Sharp Gold Tapers for Scanning Near-Field Optical Microscopy

    CERN Document Server

    Esmann, Martin; da Cunha, Bernard B; Brauer, Jens H; Vogelgesang, Ralf; Gross, Petra; Lienau, Christoph

    2013-01-01

    We investigate the radiation patterns of sharp conical gold tapers, designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM). Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the generation of strongly enhanced near-field signals. Higher order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate between the lowest and higher order eigenmodes of such a metallic taper by filtering in the spatial frequency domain. Our approach has the potential to considerably improve the signal-to-background ratio in spectroscopic experiments on the nanoscale.

  1. Survey of near-field flow calculations for nuclear waste repositories NMA L21

    International Nuclear Information System (INIS)

    A survey of methods and codes which describe the flow of groundwater and the migration of radioactive waste in and about nuclear repositories was performed. A number of laboratories engaged in studies of waste migration and groundwater flow were visited in order to discuss the general problem and obtain reports of work being performed. The results of this survey are discussed

  2. Aspects of geochemical evolution of the SKB near field in the frame of SR-Site

    International Nuclear Information System (INIS)

    The concept for the final disposal of high level nuclear waste (HLNW) developed by the Swedish Nuclear Waste Management Company (SKB) entails a multi-barrier system that surrounds the HLNW, which is also known as the near-field. In the near-field, the buffer is initially subject to a high thermal gradient induced by the heat generated by the radioactive decay of the HLNW. During this period, the buffer is also subject to a hydrodynamic pressure induced by the surrounding water saturated rock massif which progressively leads to the saturation of the buffer. After saturation and cooling of the near-field, the interaction of groundwater with the bentonite buffer may result in an evolving distribution of some aqueous species in the bentonite porewater, as well as the redistribution of accessory minerals and the cation exchanger composition in the montmorillonite interlayer. The distribution of aqueous and solid species in the buffer can affect, directly or indirectly, some of the relevant safety function indicators defined by. In this context, the work developed by Arcos et al is revisited in the present work and, based on new data from SKB, additional models are developed for the SR-Site Safety Assessment. The work presented here represents an update of the model conducted within the SR-Can exercise and, therefore, similar simulation cases are developed. Three aspects must be considered regarding the geochemical evolution of the near field: (1) the effect of the thermal period; (2) the processes during the saturation of bentonite; and, (3) the interaction of the water-saturated bentonite with the local groundwater. In this numerical exercise, two types of bentonite are analysed: the MX-80 and the Deponit CA-N. The effect of the thermal period and the water saturation are analysed in a series of one-dimensional radial-symmetric simulations performed using TOUGHREACT which is a reactive transport code that accounts for variably saturated multi-phase flow under non

  3. Calculation of Local Stress and Fatigue Resistance due to Thermal Stratification on Pressurized Surge Line Pipe

    International Nuclear Information System (INIS)

    Thermal stratification introduces thermal shock effect which results in local stress and fatigue problems that must be considered in the design of nuclear power plant components. Local stress and fatigue calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343 deg. C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.

  4. Near-Field Tsunami Early Warning and Preparedeness in the Mediterranean: the EU NEARTOWARN Project

    Science.gov (United States)

    Papadopoulos, Gerasimos; Karastathis, Vasilis; Novikova, Tatyana; Fokaefs, Anna; Minadakis, George; Papageorgiou, Antonia; Tinti, Stefano; Armigliato, Alberto; Ausilia Paparo, Maria; Zaniboni, Filippo; Georgiou, George; Aniel Quiroga, Inigo; Gonzalez, Mauricio; Alvarez-Gomez, Jose Antonio; Lesne, Olivia; Renou, Camille; Mangin, Antoine; Schindele, Francois; Argyris, Ilias

    2014-05-01

    The Mediterranean Sea region is characterized by near-field tsunamis (travel times less than 30 min.). An efficient end-to-end warning system should fulfill the condition that the time needed from an earthquake detection to evacuation is less than the arrival time of the first wave, which is a very hard task in the Mediterranean. The project NEARTOWARN, which is supported by the EU DG-ECHO prevention program aims, among others, to establish a pilot system in Rhodes island, SE Aegean Sea, Greece, with the purpose to meet needs for local tsunami early warning but applicable in other coastal zones of the Mediterranean and beyond. To minimize emergency time in less than 30 sec, seismic alert devices (SEDs) make the core component of alerting. SEDs are activated and send alerting signals as soon as a P- phase of seismic wave is detected in the near-field domain and for a predetermined threshold of ground motion. Then, emergency starts while SEDs activate remotely other devices, such as computers with data bases of pre-calculated tsunami simulations, surveillance cameras etc. The system is completed with tide- gauges, simulated tsunami scenarios and emergency planning supported by a Geographical Management System. Rhodes island in Dodecanese, Greece, has been selected as a test- area for the development of the prototype system. To promote the future development of such local systems in other coastal zones of the Mediterranean the NEARTOWARN partners review current status of early warning systems, produce digital inventories of wave travel times from several tsunami sources to a number of forecasting points, standardize data bases for pre-simulated tsunami scenarios and optimize triggering thresholds for the SED alerting networks. A local system such as the one developed by NEARTOWARN is expected to function in synergy with national and regional warning systems such as the one coordinated NEAMTWS.

  5. Chemically-doped graphene with improved surface plasmon characteristics: an optical near-field study.

    Science.gov (United States)

    Zheng, Zebo; Wang, Weiliang; Ma, Teng; Deng, Zexiang; Ke, Yanlin; Zhan, Runze; Zou, Qionghui; Ren, Wencai; Chen, Jun; She, Juncong; Zhang, Yu; Liu, Fei; Chen, Huanjun; Deng, Shaozhi; Xu, Ningsheng

    2016-10-01

    One of the most fascinating and important merits of graphene plasmonics is their tunability over a wide range. While chemical doping has proven to be a facile and effective way to create graphene plasmons, most of the previous studies focused on the macroscopic behaviors of the plasmons in chemically-doped graphene and little was known about their nanoscale responses and related mechanisms. Here, to the best of our knowledge, we present the first experimental near-field optical study on chemically-doped graphene with improved surface plasmon characteristics. By using a scattering-type scanning near-field optical microscope (s-SNOM), we managed to show that the graphene plasmons can be tuned and improved using a facile chemical doping method. Specifically, the plasmon interference patterns near the edge of the monolayer graphene were substantially enhanced via nitric acid (HNO3) exposure. The plasmon-related characteristics can be deduced by analyzing such plasmonic fringes, which exhibited a longer plasmon wavelength and reduced plasmon damping rate. In addition, the local carrier density and therefore the Fermi energy level (EF) of graphene can be obtained from the plasmonic nano-imaging, which indicated that the enhanced plasmon oscillation originated from the injection of free holes into graphene by HNO3. These findings were further corroborated by theoretical calculations using density functional theory (DFT). We believe that our findings provide a clear nanoscale picture on improving graphene plasmonics by chemical doping, which will be helpful for optimizing graphene plasmonics and for elucidating the mechanisms of two-dimensional light confinement by atomically thick materials.

  6. Indirect interband transition induced by optical near fields with large wave numbers

    Science.gov (United States)

    Yamaguchi, Maiku; Nobusada, Katsuyuki

    2016-05-01

    Optical near fields (ONFs) have Fourier components with large wave numbers that are two or three orders of magnitude larger than those of far-field propagating light owing to their nonuniformity in space. By utilizing these large wave numbers, the ONF is expected to induce an indirect interband transition between Bloch states having different wave numbers and directly generate an electron-hole pair without electron-phonon coupling. We perform time-dependent dynamics calculations of a one-dimensional periodic potential with an indirect band-gap structure and demonstrate that the ONF definitely induces an indirect interband transition. Instead of using the general Bloch boundary condition, which is usually imposed in conventional band structure calculations, we adopt an alternative boundary condition, the Born-von Kármán boundary condition, to appropriately treat indirect interband transitions. The calculated absorption spectra for the far-field and ONF excitations show different absorption edges and spectral patterns. We argue that this difference can be experimentally measured as evidence of the effects of the large wave numbers of the ONF.

  7. Cementitious Near-Field Sorption Data Base for Performance Assessment of an ILW Repository in Opalinus Clay

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, E.; Van Loon, L. R

    2003-08-01

    The present report describes a cement sorption database (SDB) for the safety-relevant radionuclides to be disposed of in the planned Swiss repository for long-lived intermediate-level radioactive wastes (ILW). This report is an update on earlier SDBs, which were compiled for the cementitious near field of a repository for low- and intermediate-level radioactive wastes (L/ILW) by BRADBURY + SAROTT (1995) and BRADBURY + VAN LOON (1998). The radionuclide inventories are determined by the waste streams to be disposed of in the ILW repository. A list of the safety-relevant radionuclides was provided based on the currently available information on ILW inventories. The compositions of the cement porewaters in the near fields of the L/ILW and ILW repositories, which had been calculated using well-established codes for modelling cement degradation, were compared to identify any differences in the near-field conditions and to assess their influence on radionuclide sorption. Sorption values were selected based on the previously reported SDBs for the near field of the L/ILW repository. Sorption values were revised if new information and/or data were available which allowed changes to or re-appraisals of the data to be made. The sorption values recommended in this report were either selected on the basis of data from in-house experimental studies or from literature data. For some key radioelements, i.e., Cs(l), Sr(II), Ni(II), Eu(lll), Th(IV) and Sn(IV), new data were available from in-house measurements. These elements had been selected for experimental studies due to their relevance to safety assessment and/or their importance as appropriate chemical analogues. Degradation products of bitumen and cellulose, concrete admixtures and cement-derived near-field colloids were taken into account as the main potential perturbations, which could reduce radionuclide sorption in the near field. Possible impacts of the perturbing factors on radionuclide mobility were considered and

  8. First-Principles Calculations of Structural, Elastic and Electronic Properties of Tetragonal HfO2 under Pressure

    Institute of Scientific and Technical Information of China (English)

    刘其军; 刘正堂; 冯丽萍

    2011-01-01

    Structural, elastic and electronic properties of tetragonal Hf02 at applied hydrostatic pressure up to 50 GPa have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first-principles density- functional theory (DFT). The calculated ground-state properties are in good agreement with previous theoretical and experimental data. Six independent elastic constants of tetragonal Hf02 have been calculated at zero pressure and high pressure. From the obtained elastic constants, the bulk, shear and Young's modulus, Poisson's coefficients, acoustic velocity and Debye temperature have been calculated at the applied pressure. Band structure shows that tetragonal Hf02 is an indirect band gap. The variation of the gap versus pressure is well fitted to a quadratic function.

  9. Pressure Calculation in Polar and Charged Systems using Ewald Summation Results for the Extended Simple Point Charge Model of Water

    CERN Document Server

    Hummer, G; Neumann, M; Hummer, Gerhard; Gr{ø}nbech-Jensen, Niels; Neumann, Martin

    1998-01-01

    Ewald summation and physically equivalent methods such as particle-mesh Ewald, kubic-harmonic expansions, or Lekner sums are commonly used to calculate long-range electrostatic interactions in computer simulations of polar and charged substances. The calculation of pressures in such systems is investigated. We find that the virial and thermodynamic pressures differ because of the explicit volume dependence of the effective, resummed Ewald potential. The thermodynamic pressure, obtained from the volume derivative of the Helmholtz free energy, can be expressed easily for both ionic and rigid molecular systems. For a system of rigid molecules, the electrostatic energy and the forces at the atom positions are required, both of which are readily available in molecular dynamics codes. We then calculate the virial and thermodynamic pressures for the extended simple point charge (SPC/E) water model at standard conditions. We find that the thermodynamic pressure exhibits considerably less system size dependence than t...

  10. Panel discussion on near-field coupled processes with emphasis on performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    Codell, R.B.; Baca, R.G.; Ahola, M.P. [and others

    1996-04-01

    The presentations in this panel discussion involve the general topic of near-field coupled processes and postclosure performance assessment with an emphasis on rock mechanics. The potential impact of near-field rock mass deformation on repository performance was discussed, as well as topics including long term excavation deterioration, the performance of geologic seals, and coupled processes concerning rock mechanics in performance assessments.

  11. Plasmonic Antennas Nanocoupler for Telecom Range: Simulation, Fabrication and Near-Field Characterization

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Lavrinenko, Andrei;

    2014-01-01

    We report simulation, fabrication and, for the first time, full amplitude-phase near-field optical characterization in telecom range of the compact and efficient plasmonic nanoantenna based couplers. Near-field data allowed characterizing the subwavelength slot waveguide’s propagation losses...

  12. Calculation of Internal Energy and Pressure of Dense hydrogen Plasma by Direct Path Integral Monte Carlo Approach

    Institute of Scientific and Technical Information of China (English)

    刘松芬; 胡北来

    2003-01-01

    The internal energy and pressure of dense hydrogen plasma are calculated by the direct path integral Monte Carlo approach. The Kelbg potential is used as interaction potentials both between electrons and between protons and electrons in the calculation. The complete formulae for internal energy and pressure in dense hydrogen plasma derived for the simulation are presented. The correctness of the derived formulae are validated by the obtained simulation results. The numerical results are discussed in details.

  13. Near field in quantum electrodynamics: Green functions, Lorentz condition, "nonlocality in the small", frustrated total reflection

    CERN Document Server

    Perel'man, M E

    2006-01-01

    Investigation of near field of QED requires the refuse from an averaging of the Lorentz condition that smooths out some field peculiarities. Instead of it Schwinger decomposition of the 4-potential with the Bogoliubov method of interaction switching in time and in space regions is considered. At such approach near field is describable by the part of covariant Green function of QED, the fast-damping Schwinger function formed by longitudinal and scalar components of Aμ none restricted by light cone. This description reveals possibility of superluminal phenomena within the near field zone as a "nonlocality in the small". Some specification of Bogoliubov method allows, as examples, descriptions of near fields of point-like charge and at FTIR phenomena. Precisely such possibilities of nonlocal interactions are revealed in the common QED expressions for the Van-der-Waals and Casimir interactions and in the F\\"{o}rster law. Key words: Lorentz condition, near field, propagators, superluminal, FTIR. PACS: 03....

  14. A Novel Algorithm Based on 3D-MUSIC Algorithm for Localizing Near-Field Source

    Institute of Scientific and Technical Information of China (English)

    SHAN Zhi-yong; ZHOU Xi-lang; PEN Gen-jiang

    2005-01-01

    A novel 3-D MUSIC algorithm based on the classical 3D-MUSIC algorithm for the location of near-field source was presented. Under the far-field assumption of actual near-field, two algebraic relations of the location parameters between the actual near-field sources and the far-field ones were derived. With Fourier transformation and polynomial-root methods, the elevation and the azimuth of the far-field were obtained, the tracking paths can be developed, and the location parameters of the near-field source can be determined, then the more accurate results can be estimated using an optimization method. The computer simulation results p rove that the algorithm for the location of the near-fields is more accurate, effective and suitable for real-time applications.

  15. Pressure Vessel Fluence Calculations for the Hungarian VVER-440 Units for the Power Uprate and the Llifetime Extension

    Directory of Open Access Journals (Sweden)

    Hordósy Gábor

    2016-01-01

    Full Text Available A major project was launched at Paks NPP, Hungary, to investigate the possibility of lifetime extension up to 60 years. At the same time, new fuel types with higher enrichment and containing pins with gadolinium have been introduced. Due to these plans, the radiation load of the pressure vessel was evaluated up to 60 years irradiation, taking into account the past and planned future cycles. The computational procedure, elaborated and validated earlier for the fast flux calculation in the pressure vessel was modified for the new fuel types. The neutron source at the core boundaries was taken from core design calculations and the neutron transport from the source to and through the pressure vessel was followed by Monte Carlo calculations. A number of calculations were performed to adequately follow the change of the neutron source. The paper details this procedure, the used Monte Carlo model, the influence of the different reloading schemes on the radiation load and the calculated results.

  16. Pressure Vessel Fluence Calculations for the Hungarian VVER-440 Units for the Power Uprate and the Llifetime Extension

    Science.gov (United States)

    Hordósy, Gábor; Hegyi, György; Keresztúri, András; Maráczy, Csaba; Temesvári, Emese; Zsolnay, Éva M.

    2016-02-01

    A major project was launched at Paks NPP, Hungary, to investigate the possibility of lifetime extension up to 60 years. At the same time, new fuel types with higher enrichment and containing pins with gadolinium have been introduced. Due to these plans, the radiation load of the pressure vessel was evaluated up to 60 years irradiation, taking into account the past and planned future cycles. The computational procedure, elaborated and validated earlier for the fast flux calculation in the pressure vessel was modified for the new fuel types. The neutron source at the core boundaries was taken from core design calculations and the neutron transport from the source to and through the pressure vessel was followed by Monte Carlo calculations. A number of calculations were performed to adequately follow the change of the neutron source. The paper details this procedure, the used Monte Carlo model, the influence of the different reloading schemes on the radiation load and the calculated results.

  17. Theoretical Calculations for Structural, Elastic and Thermodynamic Properties of γTiA1 Under High Pressure

    Institute of Scientific and Technical Information of China (English)

    FU Hong-Zhi; LI De-Hua; PENG Feng; GAO Tao; CHENG Xin-Lu

    2008-01-01

    We investigate the structural and elastic properties of γTiAl under high pressures using the norm-conserving pseudopotentials within the local density approximation (LDA) in the frame of density functional theory. The calculated pressure dependence of the elastic constants is in excellent agreement with the experimentM results. The elastic constants and anisotropy as a function of applied pressure axe presented. Through the quasi-harmonic Debye model, we also investigate the thermodynamic properties of γTiAl.

  18. Red-Shift Effects in Surface Enhanced Raman Spectroscopy: Spectral or Intensity Dependence of the Near-Field?

    KAUST Repository

    Colas, Florent

    2016-06-06

    Optimum amplification in Surface Enhanced Raman Scattering (SERS) from individual nanoantennas is expected when the excitation is slightly blue-shifted with respect to the Localized Surface Plasmon Resonance (LSPR), so that the LSPR peak falls in the middle between the laser and the Stokes Raman emission. Recent experiments have shown when moving the excitation from the visible to the near-infrared that this rule of thumb is no more valid. The excitation has to be red-shifted with respect to the LSPR peak, up to 80nm, to obtain highest SERS. Such discrepancy is usually attributed to a Near-Field (NF) to Far-Field (FF) spectral shift. Here we critically discuss this hypothesis for the case of gold nanocylinders. By combining multi-wavelength excitation SERS experiments with numerical calculations, we show that the red-shift of the excitation energy does not originate from a spectral shift between the extinction (FF) and the near-field distribution (NF), which is found to be not larger than 10nm. Rather, it can be accounted for by looking at the peculiar spectral dependence of the near-field intensity on the cylinders diameter, characterized by an initial increase, up to 180nm diameter, followed by a decrease and a pronounced skewness.

  19. Retrieving the spatial distribution of cavity modes in dielectric resonators by near-field imaging and electrodynamics simulations.

    Science.gov (United States)

    Goñi, Alejandro R; Güell, Frank; Pérez, Luis A; López-Vidrier, Julian; Ossó, J Oriol; Coronado, Eduardo A; Morante, Joan R

    2012-03-01

    For good performance of photonic devices whose working principle is based on the enhancement of electromagnetic fields obtained by confining light into dielectric resonators with dimensions in the nanometre length scale, a detailed knowledge of the optical mode structure becomes essential. However, this information is usually lacking and can only be indirectly obtained by conventional spectroscopic techniques. Here we unraveled the influence of wire size, incident wavelength, degree of polarization and the presence of a substrate on the optical near fields generated by cavity modes of individual hexagonal ZnO nanowires by combining scanning near-field optical microscopy (SNOM) with electrodynamics calculations within the discrete dipole approximation (DDA). The near-field patterns obtained with very high spatial resolution, better than 50 nm, exhibit striking size and spatial-dispersion effects, which are well accounted for within DDA, using a wavevector-dependent dipolar interaction and considering the dielectric anisotropy of ZnO. Our results show that both SNOM and DDA simulations are powerful tools for the design of optoelectronic devices able to manipulate light at the nanoscale.

  20. Pressure-induced semimetallic behavior of calcium from ab initio calculations

    International Nuclear Information System (INIS)

    A loss of metallic properties in fcc calcium under high pressure is studied ab initio using the density functional theory (DFT) and GW approximation. It is found that a more correct description of many-electron effects given by GW method does not provide significant changes in the behavior of electronic spectrum in comparison with DFT approach. We note that the obtained width of (pseudo)gap is highly sensitive to the k-point sampling used for density of states calculation. The analysis of fcc calcium's band structure at p ∼ 20 GPa shows that the crossing of bands at the Fermi level is removed if the spin-orbit coupling is taken into account.

  1. Generalized spectral method for near-field optical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, B.-Y.; Zhang, L. M.; Basov, D. N.; Fogler, M. M. [Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States); Castro Neto, A. H. [Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States); Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore 117542 (Singapore)

    2016-02-07

    Electromagnetic interaction between a sub-wavelength particle (the “probe”) and a material surface (the “sample”) is studied theoretically. The interaction is shown to be governed by a series of resonances corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe as well as on the surface reflectivity of the material. Calculation of such resonances is carried out for several types of axisymmetric probes: spherical, spheroidal, and pear-shaped. For spheroids, an efficient numerical method is developed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. Application of the method to highly resonant materials, such as aluminum oxide (by itself or covered with graphene), reveals a rich structure of multi-peak spectra and nonmonotonic approach curves, i.e., the probe-sample distance dependence. These features also strongly depend on the probe shape and optical constants of the model. For less resonant materials such as silicon oxide, the dependence is weak, so that the spheroidal model is reliable. The calculations are done within the quasistatic approximation with radiative damping included perturbatively.

  2. Evolution of near-field physico-chemical characteristics of the SFR repository

    Energy Technology Data Exchange (ETDEWEB)

    Savage, D. [Quintessa Ltd., Nottingham (United Kingdom); Stenhouse, M. [Monitor Scientific LLC, Denver, CO (United States); Benbow, S. [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2000-08-01

    The evaluation of the post-closure performance of the SFR repository needs to consider time dependent evolution of the repository environment. Time-dependent reaction of near-field barriers (cement, steel, bentonite) with saturating groundwater will lead to the development of hyper alkaline repository pore fluids, chemically reducing conditions, and ultimately, the generation of gas through anaerobic corrosion of metals. Cement and concrete will act as chemical conditioning agents to minimise metal corrosion and ultimately, maximise radioelement sorption. The chemical and physical evolution of cement and concrete through reaction with ambient groundwater will thus affect sorption processes through changes in pH, complexing ligands, and solid surface properties. It is desirable that these changes be incorporated into the safety assessment. The sorption behaviour of radionuclides in cementitious systems has been reviewed in detail. The available evidence from experimental work carried out on the influence of organic materials on the sorption behaviour of radionuclides, indicates that most organic degradation products will not affect sorption significantly at the concentrations expected in a cementitious repository. The notable exception to this conclusion involves the degradation products of cellulose and, in particular, polycarboxylic acids represented by iso-saccharinic acid (ISA). Results using ISA indicate a significant reduction in sorption of Pu, by several orders of magnitude, for an ISA concentration of about 10{sup -3} M. More recent data indicate that the negative effect is not as great, though still significant. Therefore, some scoping calculations are advisable to determine how realistic an ISA concentration of about 10{sup -3} M would be for the SFR repository and to estimate concentrations of other relevant organic compounds, in particular EDTA, for comparison. Scoping calculations relevant to the longevity of hyper alkaline pore fluid conditions at SFR

  3. Stability and toe pressure calculation of a reactor building subject to seismic disturbance

    International Nuclear Information System (INIS)

    At the present time, the stability and toe pressure calculation of a reactor building subject to seismic disturbance is still based on the equivalent inertial force method applied statically. A numerical scheme is introduced to handle this nonlinear dynamic problem with reasonable computation cost. A set of nonlinear differential equations is derived by coupling the modal information of a free-free building model with the compression only nonlinear force displacement curve representing the soil. This formulation has several advantages. Rigid body large displacement rotational mode is included in the analysis to account for the uplift; the compression only nonlinear force displacement curve can be defined at several control points along the building soil interface; the mode shapes used in the analysis are free-free. This allows for a better estimate of the importance of the building flexibility effects on soil pressure since the rigid body modes and flexible modes are separated, and the boundary restraints imposed on the rigid body or free-free modes are a function of the relative motion between the structure and soil. The set of nonlinear differential equations are solved using a digital computer code that functions as an analog computer. By using this code, the compression only nonlinear force displacement curve for the soil can easily be handled. A parametric study is conducted to evaluate the importance of uplift, building flexibility and the nonlinear force displacement curve. The results obtained are also compared with the conventional linear dynamic analysis

  4. Stability and toe pressure calculation of a reactor building subject to seismic disturbance

    International Nuclear Information System (INIS)

    At the present time, the stability and toe pressure calculations of a reactor building subject to seismic disturbance is still based on the equivalent inertial force method applied statically. This paper introduces a numerical scheme to handle this nonlinear dynamic problem with reasonable computation cost. A set of nonlinear differential equations is derived by coupling the modal information of a free-free building model with the compression only nonlinear force displacement curve representing the soil. This formulation has several advantages. These are (1) rigid body large displacement rotational mode is included in the analysis to account for the uplift, (2) the compression only nonlinear force displacement curve can be defined at several control points along the building soil interface, (3) the mode shapes used in the analysis are free-free. This allows for a better estimate of the importance of the building flexibility effects on soil pressure since the rigid body modes and flexible modes are separated, and (4) the boundary restraints imposed on the rigid body or free-free modes are a function of the relative motion between the structure and soil. The set of nonlinear differential equations are solved using a digital computer code that functions as an analog computer. By using this code, the compression only nonlinear force displacement curve for the soil can easily be handled. A parametric study is conducted to evaluate the importance of uplift, building flexibility and the nonlinear force displacement curve. The results obtained are also compared with the conventional linear dynamic analysis. (Auth.)

  5. Review of high pressure phases of calcium by first-principles calculations

    Science.gov (United States)

    Ishikawa, T.; Nagara, H.; Suzuki, N.; Tsuchiya, J.; Tsuchiya, T.

    2010-03-01

    We review high pressure phases of calcium which have obtained by recent experimental and first-principles studies. In this study, we investigated the face-centered cubic (fcc) structure, the body-centered cubic (bcc) structure, the simple cubic (sc) structure, a tetragonal P43212 [Ishikawa T et al. 2008 Phys. Rev. B 77 020101(R)], an orthorhombic Cmca [Ishikawa T et al. 2008 Phys. Rev. B 77 020101(R)], an orthorhombic Cmcm [Teweldeberhan A M and Bonev S A 2008 Phys. Rev. B 78 140101(R)], an orthorhombic Pnma [Yao Y et al. 2008 Phys. Rev. B 78 054506] and a tetragonal I4/mcm(00) [Arapan S et al. 2008 Proc. Natl. Acad. Sci. USA 105 20627]. We compared the enthalpies among the structures up to 200 GPa and theoretically determined the phase diagram of calcium. The sequence of the structural transitions is fcc (0- 3.5 GPa) → bcc (3.5 - 35.7 GPa) → Cmcm (35.7- 52GPa) → P43212 (52-109 GPa) → Cmca (109-117.4GPa) → Pnma (117.4-134.6GPa) → I4/mcm(00) (134.6 GPa -). The sc phase is experimentally observed in the pressure range from 32 to 113 GPa but, in our calculation, there is no pressure region where the sc phase is the most stable. In addition, we found that the enthalpy of the hexagonal close-packed (hcp) structure is lower than that of I4/mcm(00) above 495 GPa.

  6. Contrast analysis of near-field scanning microscopy using a metal slit probe at millimeter wavelengths

    Science.gov (United States)

    Nozokido, Tatsuo; Ishino, Manabu; Seto, Ryosuke; Bae, Jongsuck

    2015-09-01

    We describe an analytical method for investigating the signal contrast obtained in near-field scanning microscopy using a metal slit probe. The probe has a slit-like aperture at the open end of a rectangular or a parallel plate waveguide. In our method, the electromagnetic field around the metal slit aperture at the probe tip is calculated from Maxwell's equations in the Fourier domain in order to derive the electrical admittance of a sample system consisting of layered dielectrics as seen from the probe tip. A simple two-port electrical circuit terminated by this admittance is then established to calculate the complex reflection coefficient of the probe as a signal. The validity of the method is verified at millimeter wavelengths by a full-wave high frequency 3-D finite element modeler and also by experiment. The signal contrast when varying the short dimension of the slit aperture, the separation between the probe tip and the sample, and the sample thickness are successfully explained in terms of the variation in the product of the admittance and the characteristic impedance of the waveguide at the probe tip. In particular, the cause of the local minimum in the signal intensity when varying the separation is clarified.

  7. Near-field entrainment in black smoker plumes

    Science.gov (United States)

    Smith, J. E.; Germanovich, L. N.; Lowell, R. P.

    2013-12-01

    In this work, we study the entrainment rate of the ambient fluid into a plume in the extreme conditions of hydrothermal venting at ocean floor depths that would be difficult to reproduce in the laboratory. Specifically, we investigate the flow regime in the lower parts of three black smoker plumes in the Main Endeavour Field on the Juan de Fuca Ridge discharging at temperatures of 249°C, 333°C, and 336°C and a pressure of 21 MPa. Such flow conditions are typical for ocean floor hydrothermal venting but would be difficult to reproduce in the laboratory. The centerline temperature was measured at several heights in the plume above the orifice. Using a previously developed turbine flow meter, we also measured the mean flow velocity at the orifice. Measurements were conducted during dives 4452 and 4518 on the submersible Alvin. Using these measurements, we obtained a range of 0.064 - 0.068 for values of the entrainment coefficient α, which is assumed constant near the orifice. This is half the value of α ≈ 0.12 - 0.13 that would be expected for plume flow regimes based on the existing laboratory results and field measurements in lower temperature and pressure conditions. In fact, α = 0.064 - 0.068 is even smaller than the value of α ≈ 0.075 characteristic of jet flow regimes and appears to be the lowest reported in the literature. Assuming that the mean value α = 0.066 is typical for hydrothermal venting at ocean floor depths, we then characterized the flow regimes of 63 black smoker plumes located on the Endeavor Segment of the Juan de Fuca Ridge. Work with the obtained data is ongoing, but current results indicate that approximately half of these black smokers are lazy in the sense that their plumes exhibit momentum deficits compared to the pure plume flow that develops as the plume rises. The remaining half produces forced plumes that show the momentum excess compared to the pure plumes. The lower value of the entrainment coefficient has important

  8. Apertureless scanning near-field optical microscopy and manipulation of nanostructures at electrified interfaces

    International Nuclear Information System (INIS)

    The introduction of lithographic processes based on the use of masks allowed a tremendous step forward in miniaturisation and commercialisation of high-end electronic components. Although the advantages of mask based lithographic processes are overwhelming, they all have to deal with the same restriction, known as the Abbe Limit, which limits the highest possible resolution to the half of the wavelength of the used light. To overcome this constriction a new method was investigated, which is based on nonpropagating waves at the end of a pointed probe to produce surface features with minimal size smaller than 10 nm. The so called apertureless near-field microscope, deals with a laser illuminated tip located at small distance (several nanometres) to a substrate. Therefore classical diffraction (Frauenhofer) doesn't come into account but near-field diffraction (Fresnel) is getting important. The achievable resolution limit is then given by the radius of curvature of the used tip (typ. ∼ 10 nm). If the geometry and illumination properties are chosen carefully, extremely high field enhancement (up to 106) can be realised at the end of the tip, due to the antenna effect, geometrical singularities and surface plasmon resonance. This work started with theoretical investigations, based on a specially designed Matlab toolbox, using the Boundary Element Method to calculate the influence of various experimental parameters e.g. polarisation, dielectric properties etc. on the field enhancement factor. Moreover thermo-mechanical studies were performed to understand the behaviour of the heated cantilever system due to laser illumination and rule out awkward experimental setups. The calculated results could be verified experimentally. The mechanism of surface modification was studied with three different AFM (Atomic Force Microscope) working modes (contact, semi-contact, non-contact) at different laser parameters (repetition rate, polarisation, energy, angle of incidence etc

  9. Engine jet entrainment in the near field of an aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, F.; Jacquin, L.; Laverdant, A. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France)

    1997-12-31

    A simplified approach has been applied to analyse the mixing and entrainment processes of the engine exhaust through their interaction with the vortex wake of an aircraft. These investigations are focused on the near filed, extending from exit nozzle to the beginning of the vortex phase (i.e. to about twenty seconds after the wake is generated). This study is performed using an integral model and a numerical simulation for a two-engine large civil aircraft. The properties of the wing-tip vortices on the calculation of the dilution ratio (defined as a tracer concentration) have been shown. The mixing process is also affected by the buoyancy effect, but only after the jet regime, when the trapping in the vortex core has occurred. Qualitative comparison with contrail photography shows similar features. Finally the distortion and stretching of the plume streamlines inside the vortices can be observed, and the role of the descent of the vortices on the maximum tracer concentration has been discussed. (author) 19 refs.

  10. EARLY DETECTION OF NEAR-FIELD TSUNAMIS USING UNDERWATER SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    L. E. Freitag

    2012-01-01

    Full Text Available We propose a novel approach for near-field tsunami detection, specifically for the area near the city of Padang, Indonesia. Padang is located on the western shore of Sumatra, directly across from the Mentawai segment of the Sunda Trench, where accumulated strain has not been released since the great earthquake of 1797. Consequently, the risk of a major tsunamigenic earthquake on this segment is high. Currently, no ocean-bottom pressure sensors are deployed in the Mentawai basin to provide a definitive tsunami warning for Padang. Timely warnings are essential to initiate evacuation procedures and minimize loss of human life. Our approach augments existing technology with a network of underwater sensors to detect tsunamis generated by an earthquake or landslide fast enough to provide at least 15 minutes of warning. Data from the underwater sensor network would feed into existing decision support systems that accept input from land and sea-based sensors and provide warning information to city and regional authorities.

  11. Surface accuracy measurement of a deployable mesh reflector by planar near-field scanning

    Science.gov (United States)

    Chujo, Wataru; Ito, Takeo; Hori, Yoshiaki; Teshirogi, Tasuku

    1988-06-01

    Using a near-field antenna measurement facility, it is possible to simultaneously evaluate the surface accuracy of a reflector antenna as well as the far-field pattern of the antenna for a short time. The surface errors of a 2-m deployable mesh reflector for satellite use were measured by a planar near-field system. As a result, the influence of periodic structures, due to the antenna ribs, has been clearly observed. Also, the surface accuracy obtained with the near-field scanning technique has coincided well with that obtained by an optical measurement technique.

  12. Supersonic acoustic intensity with statistically optimized near-field acoustic holography

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn

    2011-01-01

    The concept of supersonic acoustic intensity was introduced some years ago for estimating the fraction of the flow of energy radiated by a source that propagates to the far field. It differs from the usual (active) intensity by excluding the near-field energy resulting from evanescent waves...... to the information provided by the near-field acoustic holography technique. This study proposes a version of the supersonic acoustic intensity applied to statistically optimized near-field acoustic holography (SONAH). The theory, numerical results and an experimental study are presented. The possibility of using...

  13. Near-field to far-field characterization of speckle patterns generated by disordered nanomaterials

    CERN Document Server

    Parigi, Valentina; Binard, Guillaume; Bourdillon, Céline; Maître, Agnès; Carminati, Rémi; Krachmalnicoff, Valentina; De Wilde, Yannick

    2016-01-01

    We study the intensity spatial correlation function of optical speckle patterns above a disordered dielectric medium in the multiple scattering regime. The intensity distributions are recorded by scanning near-field optical microscopy (SNOM) with sub-wavelength spatial resolution at variable distances from the surface in a range which spans continuously from the near-field (distance $ \\ll \\lambda $) to the far-field regime (distance $\\gg \\lambda $). The non-universal behavior at sub-wavelength distances reveals the connection between the near-field speckle pattern and the internal structure of the medium.

  14. Near-field to far-field characterization of speckle patterns generated by disordered nanomaterials.

    Science.gov (United States)

    Parigi, Valentina; Perros, Elodie; Binard, Guillaume; Bourdillon, Céline; Maître, Agnès; Carminati, Rémi; Krachmalnicoff, Valentina; De Wilde, Yannick

    2016-04-01

    We study the intensity spatial correlation function of optical speckle patterns above a disordered dielectric medium in the multiple scattering regime. The intensity distributions are recorded by scanning near-field optical microscopy (SNOM) with sub-wavelength spatial resolution at variable distances from the surface in a range which spans continuously from the near-field (distance ≪ λ) to the far-field regime (distance ≫ λ). The non-universal behavior at sub-wavelength distances reveals the connection between the near-field speckle pattern and the internal structure of the medium. PMID:27136995

  15. Enhanced near-field heat flow of a monolayer dielectric island.

    Science.gov (United States)

    Worbes, Ludwig; Hellmann, David; Kittel, Achim

    2013-03-29

    We have investigated the influence of thin films of a dielectric material on the near-field mediated heat transfer at the fundamental limit of single monolayer islands on a metallic substrate. We present spatially resolved measurements by near-field scanning thermal microscopy showing a distinct enhancement in heat transfer above NaCl islands compared to the bare Au(111) film. Experiments at this subnanometer scale call for a microscopic theory beyond the macroscopic fluctuational electrodynamics used to describe near-field heat transfer today. The method facilitates the possibility of developing designs of nanostructured surfaces with respect to specific requirements in heat transfer down to a single atomic layer.

  16. Surface Plasmon mediated near-field imaging and optical addressing in nanoscience

    CERN Document Server

    Drezet, A; Krenn, J R; Brun, M; Huant, S

    2007-01-01

    We present an overview of recent progress in plasmonics. We focus our study on the observation and excitation of surface plasmon polaritons (SPPs) with optical near-field microscopy. We discuss in particular recent applications of photon scanning tunnelling microscope (PSTM) for imaging of SPP propagating in metal and dielectric wave guides. We show how near-field scanning optical microscopy (NSOM) can be used to optically and actively address remotely nano-objects such as quantum dots. Additionally we compare results obtained with near-field microscopy to those obtained with other optical far-field methods of analysis such as leakage radiation microscopy (LRM).

  17. The optical near-field speckles and their first order statistics on the basis of the integral equations of electromagnetic field

    Institute of Scientific and Technical Information of China (English)

    CHENG Chuanfu; SONG Hongsheng; LIU Chunxiang; REN Xiaorong; ZHANG Ningyu; TENG Shuyun; XU Zhizhan

    2004-01-01

    From Helmholtz equation of the harmonic electromagnetic waves, the integral equations of the light field at the medium boundaries are obtained by use of the Green's theorem and are discretized into linear equation set with the values of the light field and its derivative as the unknowns. On solving the linear equation set, we realize the rigorous computations of the light fields at the boundaries. Then the intensities of the light waves scattered by the random self-affine fractal surfaces in the optical near-field are calculated, and the propagation characteristics, the evolutions of the contrast and the intensity probability density function of the near-field speckles are studied in detail. The near-field speckles are much different from the conventional speckles in the diffraction regions and in the imaging systems. There are obvious local fluctuations in the intensity distributions of the near-field speckles and such fluctuations disappear after propagating a distance of one wavelength from the medium surfaces. For the random surfaces with smaller lateral correlation lengths, the speckle contrasts approach the saturation values and the speckle fields approach Gaussian distribution within the near-field, while for the random surfaces with larger lateral correlation lengths, such evolutions become comparatively slow.

  18. Mapping the radiative and non-radiative local density of states in the near-field of a gold nanoantenna

    CERN Document Server

    Cao, D; Calabrese, M; Pierrat, R; Bardou, N; Collin, S; Carminati, R; Krachmalnicoff, V; De Wilde, Y

    2014-01-01

    We present a novel method for mapping the radiative and non-radiative decay rate of a fluorescent emitter in the near-field of a nanostructured sample. The approach is based on the simultaneous mapping of the fluorescence intensity and decay rate and on the rigorous application of the reciprocity theorem. Data analysis is based on an analytical calculation which is detailed in the paper. Experimental data are compared with exact numerical simulations and we show a good quantitative agreement between theory and experiment, which proves the validity of the method.

  19. The exact solution of self-consistent equations in the scanning near-field optic microscopy problem

    DEFF Research Database (Denmark)

    Lozovski, Valeri; Bozhevolnyi, Sergey I.

    1999-01-01

    for solving the self-consistent integral equation. The method developed is applied to calculations of near-field optical images obtained in illumination mode. It is assumed that the system under consideration consists of an object illuminated by the field scattered by a small probe. This assumption allows us...... to consider multiple scattering between a (point-like) probe and an extended object as well as inside the object. The exact solution for the self-consistent field is then obtained in terms of effective susceptibility of the probe-object system. Application of our method to the description of orientation...

  20. HYDROSTATIC PRESSURE CALCULATION AND OPTIMIZATION FOR DESIGN OF BEAM & SLIDE-REST GUIDEWAYS IN HEAVY DUTY CNC VERTICAL TURNING MILL

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming; HUANG Zhengdong; LI Bin; CHEN Liping

    2007-01-01

    Aiming at the approximate error of commonly used methods on calculation of hydrostatic pressures of closed hydrostatic guideways with multiple pockets, a more accurate solution is proposed. Taking design of beam & slide-rest guideways for a heavy duty CNC vertical turning mill as an example, under an assumption that stiffnesses of guideways and their jointing structure are sufficiently large, the pressures of the pockets can be attained by adding a co-planarity equation that con strains pocket centers. Then, an optimization model is built to minimize the highest pocket pressure under additional constraints that are posed on the highest seal margin pressure, the highest levitating pressure of the pockets, and the maximum deformation of the guideways. The optimization problem is solved sequentially by using the methods of design of experiments and adaptive simulated annealing on iSIGHT software platform. The results show significant improvements to the original design. Optimized maximum hydrostatic pressure meets the requirement of hydraulic system.

  1. Dielectric properties of concrete at S and X bands: a near-field investigation

    Science.gov (United States)

    Bois, Karl J.; Benally, Aaron D.; Nowak, Paul S.; Zoughi, Reza

    1999-10-01

    When inspecting concrete structures with microwaves (radars, embedded microwave sensors, modulated scattering techniques, etc.) the dielectric properties of the concrete are considered as a ground truth data and must be known. During the past three years, extensive microwave near-field measurements of the reflection properties of concrete specimens with varying water-to-cement (w/c) ratios, sand-to-cement (s/c) ratios and coarse aggregate-to-cement (ca/c) ratios have been conducted. These experiments were conducted using open-ended rectangular waveguide probes radiating into a half-space of these concrete specimens. These measurements were conducted at S- (2.6 - 3.95 GHz) and X-bands (8.2 - 12.4 GHz). Moreover, an electromagnetic model, which took into account the presence of higher-order modes at the waveguide aperture, was also used to model this process. Finally, a root finding technique was applied to calculate the effective dielectric properties of the concrete specimens. This paper presents the results of these measurements and calculations as they related to determining the dielectric properties of concrete. Since concrete is a heterogeneous material, the results from many locations in a specimen are reported rendering effective dielectric properties showing the mean and standard deviation of the measurements and calculations at these frequency bands. The results of the dielectric constant can also be used to predict the reflection properties of concrete when using a standoff distance (i.e. non-contact measurements) or when using other types of microwave sensors.

  2. NEARTOWARN: A new EU-DG ECHO-supported project for the near-field tsunami early warning

    Science.gov (United States)

    Papadopoulos, G. A.

    2012-04-01

    the near-field but for a predetermined threshold of ground motion. Then, emergency starts while SED's activate remotely other devices, such as computers with data bases of pre-calculated tsunami simulations, surveillance cameras etc. The system is completed with tide-gauges, simulated tsunami scenarios and emergency planning supported by a Geographical Management System. Rhodes island in Dodecanese, South Aegean Sea, Greece, has been selected as a test-area for the development of the prototype system.

  3. Application of Near-Field Emission Processing for Microwave Circuits under Ultra-Short Duration Perturbations

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2012-10-01

    Full Text Available This paper is dealing with a time-frequency modeling method of electromagnetic (EM near-field (NF radiated by electronic devices excited by transient pulse signals. The model developed enables to calculate the EM NF maps at different distances from the given device and also the synthesis of radiation sources enabling to reproduce the field maps. The method proposed is based on the ultra wide band (UWB frequency model of EM NF maps. The number of EM NF maps can be reduced by considering an innovative algorithm in order to establish simply the dipole model. Then, the transient model can be realized by considering the convolution between the transient excitation signals and the dipole-array model. The method proposed was validated by a standard 3D EM tool with a planar microstrip device excited by microwave signal modulating 1.25-GHz-carrier with 0.5-GHz-bandwidth. As expected, good correlation is found between results from simulation and the investigated modelling method.  The method introduced in this paper is particularly useful for the investigation of time-domain emissions for EMC applications by considering transient EM interferences (EMIs.

  4. Analysis of point fabrication model for near-field photolithography with experimental study.

    Science.gov (United States)

    Lin, Zone-Ching; Yang, Ching-Been

    2006-01-01

    For the Gaussian beam, the power density distribution of the aluminum-coated optical tapered fiber probe is discussed and a theoretical fixed-point fabrication model for near-field photolithography is established. The energy density theorem is used to explore the surface exposure of photoresist, which is divided into multiple grids to evaluate the changes in the concentration of photoactive compounds at specific nodes of the interior layer. The full width at half maximum (FWHM) and the contour of the photolithograph following development are then calculated. The fixed-point lithographic experiment and aperture verification of the optic fiber probe are performed to confirm the reliability of the present model, and Dill A, B, C parameters are first measured in this article. According to the experimental results, a better image of the probe aperture can be achieved by increasing the conductivity of the measured articles and reducing the electric charges during the image taken by field-emission scanning electron microscope. The FWHM measured is 166.6 nm, while the measured average probe aperture size is 317.4 nm and the FWHM simulated by the proposed model is 151.3 nm. The error between experiment and simulation is <-9.2%. It is thus concluded that the proposed theoretical model is reasonable and acceptable. PMID:16502624

  5. Concentration statistics of solute transport for the near field zone of an estuary

    Science.gov (United States)

    Galesic, Morena; Andricevic, Roko; Gotovac, Hrvoje; Srzic, Veljko

    2016-08-01

    Rivers are considered as one of the most influential hydrological pathways for the waterborne transport and therefore estuaries are critical areas for a pollution hazard that might lead to eutrophication and general water quality deterioration. This paper is investigating the near field mixing in the estuary as the result of a combination of small scale turbulent diffusion and a larger scale variation of the advective mean velocities. In this work concentration moments were developed directly from the fundamental advection-diffusion equation for the case of continuous, steady, conservative solute transport with the dominant stream flow mean velocity. The concentration statistics were developed considering depth integrated velocity field with mean velocity attenuation due to the wind induced currents and sea tides. In order to perform further studies of developed concentration moments, a set of velocity measurements in the local river Žrnovnica estuary near Split, Croatia, was conducted and numerical random walk particle tracking model was used to run the transport simulations based on measured velocity fields. The numerical model has confirmed quantitatively first two concentration moments, which are utilized to calculate the point concentration probability density function (pdf) often needed to assess the risk of exceeding the allowed concentration values in the estuary.

  6. Hybrid modelling of near-field coupling onto grounded wire under ultra-short duration perturbation

    Science.gov (United States)

    Ravelo, B.; Liu, Y.

    2014-10-01

    A time-frequency (TF) hybrid model (HM) for investigating the interaction between EM near-field (NF) aggression and grounded wire is addressed. The HM is based on the combination of techniques for extracting the EM NF radiated by electronic structures and the calculation of electrical disturbances across the wire due to EM coupling. The computation method is fundamentally inspired from transmission line (TL) theory under EM illumination. The methodology including flow chart interpreting the routine algorithm based on the combination of frequency and time domain approaches is featured. An experimental result showing the EM coupling between patch antenna-wire from 1.5-3.5GHz reveals the efficiency of the HM in frequency domain. The relevance of this HM was illustrated with a structure comprised of 20cm aggressor and 5cm victim I-shaped wires placed above a planar ground plane. The aggressor was excited with 40ns duration perturbation signal. After Matlab implementation of the HM, the disturbance voltages across the extremity of the victim wire were extracted. This simple and fast HM is useful for the EMC engineering during the design and fabrication phases of electrical and electronic systems.

  7. Near-field thermal emission between corrugated surfaces separated by nano-gaps

    Science.gov (United States)

    Didari, Azadeh; Pinar Mengüç, M.

    2015-06-01

    Near-field thermal radiation with its many potential applications in different fields requires a thorough understanding for the development of new devices. In this paper, we report that near-field thermal emission between two parallel SiC thin films separated by a nano-gap, supporting surface phonon polaritons, as modeled via Finite Difference Time Domain Method (FDTD), can be enhanced when structured nanoparticles of different shapes and sizes are present on the surface of the emitting films. We compare different nano-particle shapes and discuss the configurations, which have the highest impact on the enhancement of near-field thermal emission and on the near-field heat flux. Convolutional Perfectly Matched Layer (CPML) boundary condition is used as the boundary condition of choice as it was determined to give the most accurate results compared against the other methodologies when working with sub-wavelength structures.

  8. Modulating the Near Field Coupling through Resonator Displacement in Planar Terahertz Metamaterials

    Science.gov (United States)

    Mohan Rao, S. Jagan; Kumar, Deepak; Kumar, Gagan; Chowdhury, Dibakar Roy

    2016-10-01

    We present the effect of vertical displacements between the resonators inside the unit cell of planar coupled metamaterials on their near field coupling and hence on the terahertz (THz) wave modulation. The metamolecule design consists of two planar split- ring resonators (SRRs) in a unit cell which are coupled through their near fields. The numerically simulated transmission spectrum is found to have split resonances due to the resonance mode hybridization effect. With the increase in displacement between the near field coupled SRRs, this metamaterial system shows a transition from coupled to uncoupled state through merging of the split resonances to the single intrinsic resonance. We have used a semi-analytical model describing the effect of displacements between the resonators and determine that it can predict the numerically simulated results. The outcome could be useful in modulating the terahertz waves employing near field coupled metamaterials, hence, can be useful in the development of terahertz modulators and frequency tunable devices in future.

  9. Infrared near-field imaging and spectroscopy based on thermal or synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Peragut, Florian; De Wilde, Yannick, E-mail: yannick.dewilde@espci.fr [ESPCI ParisTech, PSL Research University, CNRS, Institut Langevin, 1 rue Jussieu, F-75005, Paris (France); Brubach, Jean-Blaise; Roy, Pascale [Société Civile Synchrotron SOLEIL, L' Orme des Merisiers, St-Aubin BP48, 91192 Gif-sur-Yvette Cedex (France)

    2014-06-23

    We demonstrate the coupling of a scattering near-field scanning optical microscope combined with a Fourier transform infrared spectrometer. The set-up operates using either the near-field thermal emission from the sample itself, which is proportional to the electromagnetic local density of states, or with an external infrared synchrotron source, which is broadband and highly brilliant. We perform imaging and spectroscopy measurements with sub-wavelength spatial resolution in the mid-infrared range on surfaces made of silicon carbide and gold and demonstrate the capabilities of the two configurations for super-resolved near-field mid-infrared hyperspectral imaging and that the simple use of a properly chosen bandpass filter on the detector allows one to image the spatial distribution of materials with sub-wavelength resolution by studying the contrast in the near-field images.

  10. Nanohybrids Near-Field Optical Microscopy: From Image Shift to Biosensor Application

    Directory of Open Access Journals (Sweden)

    Nayla El-Kork

    2016-01-01

    Full Text Available Near-Field Optical Microscopy is a valuable tool for the optical and topographic study of objects at a nanometric scale. Nanoparticles constitute important candidates for such type of investigations, as they bear an important weight for medical, biomedical, and biosensing applications. One, however, has to be careful as artifacts can be easily reproduced. In this study, we examined hybrid nanoparticles (or nanohybrids in the near-field, while in solution and attached to gold nanoplots. We found out that they can be used for wavelength modulable near-field biosensors within conditions of artifact free imaging. In detail, we refer to the use of topographic/optical image shift and the imaging of Local Surface Plasmon hot spots to validate the genuineness of the obtained images. In summary, this study demonstrates a new way of using simple easily achievable comparative methods to prove the authenticity of near-field images and presents nanohybrid biosensors as an application.

  11. Calculations of High-Pressure Properties of Beryllium: Construction of a Multiphase Equation of State

    Energy Technology Data Exchange (ETDEWEB)

    Benedict, L; Ogitsu, T

    2008-07-24

    We describe the construction of a three-phase equation of state (EOS) for elemental beryllium. The phases considered are: the ambient hcp phase, the high-temperature bcc phase, and the liquid. The free energies of the solid phases are constructed from cold, ion-thermal, and electron-thermal components derived from ab initio electronic structure-based calculations. We find that the bcc phase is unstable near ambient conditions, and that even at high pressures at which the bcc phase is stable, the bcc-hcp energy barrier can be as small as a few hundred Kelvins. The liquid free energy is based on a model of Chisolm and Wallace and is constrained by using the melt curve (determined by ab initio 2-phase simulations) as a reference. The high-temperature plasma limit is addressed with an average-atom-in-jellium model. Comparisons to experimental results, both for the ambient hcp phase, and for the phase diagram as a whole, are discussed.

  12. Application of modified yield criteria for calculation of safe pressures on the subgrade soil

    Directory of Open Access Journals (Sweden)

    A.L. Kalinin

    2013-06-01

    Full Text Available The article deals with design the road constructions by ensuring the shear resistance of the subgrade soil and pavement layers made of weakly cohesive materials. The analysis of Mohr–Coulomb plasticity criterion was performed and it was found, that in case of a limiting condition state by this criterion pavement smoothness goes out of the limits regulated by normative documents. On the basis of analysis of Drucker-–Prager yield criterion there were obtained formulas connecting ultimate strength uniaxial compression and tension with the parameters of Mohr-Coulomb failure envelope. Substitution of these expressions into the original criteria for the strength of materials, that are continuums, allowed modifying certain conditions so that the tensile strength changed the angle of internal friction and cohesion. A number of dependencies for calculating safe pressure on discrete material of half-space is obtained from the modified conditions of plasticity. Comparison of the numerical results to experimental data allowed determining the most suitable formula for the design of road constructions.

  13. Diverse radiofrequency sensitivity and radiofrequency effects of mobile or cordless phone near fields exposure in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Styliani Geronikolou

    Full Text Available INTRODUCTION: The impact of electromagnetic fields on health is of increasing scientific interest. The aim of this study was to examine how the Drosophila melanogaster animal model is affected when exposed to portable or mobile phone fields. METHODS/RESULTS: Two experiments have been designed and performed in the same laboratory conditions. Insect cultures were exposed to the near field of a 2G mobile phone (the GSM 2G networks support and complement in parallel the 3G wide band or in other words the transmission of information via voice signals is served by the 2G technology in both mobile phones generations and a 1880 MHz cordless phone both digitally modulated by human voice. Comparison with advanced statistics of the egg laying of the second generation exposed and non-exposed cultures showed limited statistical significance for the cordless phone exposed culture and statistical significance for the 900 MHz exposed insects. We calculated by physics, simulated and illustrated in three dimensional figures the calculated near fields of radiation inside the experimenting vials and their difference. Comparison of the power of the two fields showed that the difference between them becomes null when the experimental cylinder radius and the height of the antenna increase. CONCLUSIONS/SIGNIFICANCE: Our results suggest a possible radiofrequency sensitivity difference in insects which may be due to the distance from the antenna or to unexplored intimate factors. Comparing the near fields of the two frequencies bands, we see similar not identical geometry in length and height from the antenna and that lower frequencies tend to drive to increased radiofrequency effects.

  14. Hyperbolic waveguide for long-distance transport of near-field heat flux

    Science.gov (United States)

    Messina, Riccardo; Ben-Abdallah, Philippe; Guizal, Brahim; Antezza, Mauro; Biehs, Svend-Age

    2016-09-01

    Heat flux exchanged between two hot bodies at subwavelength separation distances can exceed the limit predicted by the blackbody theory. However, this super-Planckian transfer is restricted to these separation distances. Here we demonstrate the possible existence of a super-Planckian transfer at arbitrary large separation distances if the interacting bodies are connected in the near field with weakly dissipating hyperbolic waveguides. This result opens the way to long-distance transport of near-field thermal energy.

  15. Three-dimensional mapping of optical near field of a nanoscale bowtie antenna

    OpenAIRE

    Guo, Rui; Kinzel, Edward C; Li, Yan; Uppuluri, Sreemanth M. V.; Raman, Arvind; Xu, Xianfan

    2010-01-01

    Ridge nanoscale aperture antennas have been shown to be a high transmission nanoscale light source. They provide a small, polarization-dependent near-field optical spot with much higher transmission efficiency than circularly-shaped apertures with similar field confinement. This provides significant motivations to understand the electromagnetic fields in the immediate proximity to the apertures. This paper describes an experimental three-dimensional optical near-field mapping of a bowtie nano...

  16. Phonon-Polaritons enhance near field thermal transfer across the phase transition of VO2

    OpenAIRE

    Van Zwol, Pieter; Joulain, Karl; Ben-Abdallah, Philippe; Chevrier, Joël

    2011-01-01

    International audience We show numerically that near field heat flux can be modulated by orders of magnitude upon switching from the metallic to the insulating phase of vanadium dioxide. Furthermore the resonant phonon polariton interaction for the insulating phase enhances near field thermal transfer by 3 orders of magnitude. The effect should therefore be measureable with existing experimental setups and could find broad applications for systems where thermal control at the nanoscale is ...

  17. Near-Field Radiative Heat Transfer between Metamaterials coated with Silicon Carbide Film

    OpenAIRE

    Basu, Soumyadipta; Yang, Yue; Wang, Liping

    2014-01-01

    In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC.By careful tuning of the optical properties of metamaterial it is possible to excite electrical and magnetic resonance for the meta...

  18. Quantification of source-term profiles from near-field geochemical models

    International Nuclear Information System (INIS)

    A geochemical model of the near-field is described which quantitatively treats the processes of engineered barrier degradation, buffering of aqueous chemistry by solid phases, nuclide solubilization and transport through the near-field and release to the far-field. The radionuclide source-terms derived from this model are compared with those from a simpler model used for repository safety analysis. 10 refs., 2 figs., 2 tabs

  19. Unidirectional light propagation through two-layer nanostructures based on optical near-field interactions

    CERN Document Server

    Naruse, Makoto; Ishii, Satoshi; Drezet, Aurélien; Huant, Serge; Hoga, Morihisa; Ohyagi, Yasuyuki; Matsumoto, Tsutomu; Tate, Naoya; Ohtsu, Motoichi

    2014-01-01

    We theoretically demonstrate direction-dependent polarization conversion efficiency, yielding unidirectional light transmission, through a two-layer nanostructure by using the angular spectrum representation of optical near-fields. The theory provides results that are consistent with electromagnetic numerical simulations. This study reveals that optical near-field interactions among nanostructured matter can provide unique optical properties, such as the unidirectionality observed here, and offers fundamental guiding principles for understanding and engineering nanostructures for realizing novel functionalities.

  20. The near-field acoustic levitation of high-mass rotors

    Science.gov (United States)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  1. Prediction and near-field observation of skull-guided acoustic waves

    OpenAIRE

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2016-01-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field properties unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoaco...

  2. The near-field acoustic levitation of high-mass rotors

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-10-15

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  3. The near-field acoustic levitation of high-mass rotors.

    Science.gov (United States)

    Hong, Z Y; Lü, P; Geng, D L; Zhai, W; Yan, N; Wei, B

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope. PMID:25362441

  4. Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM

    OpenAIRE

    Dongshi Guan; Zhi Hong Hang; Zsolt Marcet; Hui Liu; I. I. Kravchenko; Chan, C. T.; Chan, H. B.; Penger Tong

    2015-01-01

    Plasmonic nanostructures have attracted much attention in recent years because of their potential applications in optical manipulation through near-field enhancement. Continuing experimental efforts have been made to develop accurate techniques to directly measure the near-field optical force induced by the plasmonic nanostructures in the visible frequency range. In this work, we report a new application of dynamic mode atomic force microscopy (DM-AFM) in the measurement of the enhanced optic...

  5. Effect of plasmonic near field on the emittance of plasmon-enhanced photocathode

    CERN Document Server

    Jiang, Zeng-gong; Li, Xu-dong; Zhang, Meng; Gu, Duan

    2016-01-01

    The introduction of the surface plasmon polarizations makes the emittance of the photocathode complicated. In this paper, the emittance of plasmon-enhanced photocathode is analyzed. It is first demonstrated that the plasmonic near field can increase the emittance of the plasmon-enhanced photocathode. A simulation method has been used to estimate the emittance caused by plasmonic near field, and the suppression method also has been discussed, both of which are significant for the design of high performance plasmon-enhanced photocathode.

  6. PCB current identification based on near-field measurements using preconditioning and regularization

    Science.gov (United States)

    Rinas, Denis; Ahl, Patrick; Frei, Stephan

    2016-09-01

    Radiated electromagnetic fields from a PCB can be estimated when the source current distribution is known. From a measured near-field distribution, the PCB source current distribution can be found. Accuracy depends on the measurement method and its limitations, the radiation model and the choice of the observation area. Many known methods are based on optimization algorithms for inverse problems that vary a set of elementary radiation sources and create a radiation model. However, apart from the time-consuming optimization process, such methods find one possible solution for a near-field distribution. As this distribution might not reflect the real current distribution, accuracy outside of near-field scan area can be low. Furthermore numerical problems can often be observed. Solving the given inverse problem with a system of linear equations and complex near-field data it can be very sensitive to noise. Regularization methods and an adjusted preconditioning can increase the accuracy. In this paper, an improved radiation model creation approach based on complex near-field data is presented. This approach is based on regularization methods and extended by current estimations from near-field data. Preconditioning is done considering some physical properties of the PCB and its possible current paths. Accuracy and stability of the method are investigated in the presence of noisy data.

  7. Vibrational near-field mapping of planar and buried three-dimensional plasmonic nanostructures.

    Science.gov (United States)

    Dregely, Daniel; Neubrech, Frank; Duan, Huigao; Vogelgesang, Ralf; Giessen, Harald

    2013-01-01

    Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light-matter coupling and is of special interest for applications such as radiation engineering, attomolar sensing and nonlinear optics. Most experimental approaches to measure near-fields employ either diffraction-limited far-field methods or intricate near-field scanning techniques. Here, using diffraction-unlimited far-field spectroscopy in the infrared, we directly map the intensity of the electric field close to plasmonic nanoantennas. We place a patch of probe molecules with 10 nm accuracy at different locations in the near-field of a resonant antenna and extract the molecular vibrational excitation. We map the field intensity along a dipole antenna and gap-type antennas. Moreover, this method is able to assess the near-field intensity of complex buried plasmonic structures. We demonstrate this by measuring for the first time the near-field intensity of a three-dimensional plasmonic electromagnetically induced transparency structure.

  8. Characterization of viscous biofuel sprays using digital imaging in the near field region

    International Nuclear Information System (INIS)

    Highlights: • Biodiesel, vegetable oil and glycerin sprays have been studied using PDIA. • The study is focused on the effect of fuel viscosity on the spray characteristics. • Viscosity has a strong effect on the breakup length in pressure-swirl atomization. • The results are compared to combustion experiments with a micro gas turbine. • The penetration depth of ligaments can be a critical factor in burning viscous fuel. - Abstract: The atomization of biodiesel, vegetable oil and glycerin has been studied in an atmospheric spray rig by using digital imaging (PDIA). Images of the spray were captured in the near field, just 18 mm downstream of the atomizer, and processed to automatically determine the size of both ligaments and droplets. The effect of the spray structure in this region is of major interest for the combustion of biofuels in gas turbines. The sprays were produced by a pressure-swirl atomizer that originates from the multifuel micro gas turbine (MMGT) setup. Various injection conditions have been tested to investigate the influence of viscosity on the spray characteristics and to assess the overall performance of the atomizer. The spray measurements have been compared to combustion experiments with biodiesel and vegetable oil in the micro gas turbine at similar injection conditions. The results show that the primary breakup process rapidly deteriorates when the viscosity is increased. A higher viscosity increases the breakup length, which becomes visible at the measurement location in the form of ligaments. This effect leads to an unacceptable spray quality once the viscosity slightly exceeds the typical range for conventional gas turbine fuels. The SMD in the investigated spray region was not significantly affected by viscosity, but mainly influenced by injection pressure. The data furthermore indicate an increase in SMD with surface tension. It was found that the penetration depth of ligaments can have major impact on the combustion process

  9. First-principles calculations of elasticity and thermodynamic properties of LaNi5 crystal under pressure

    Institute of Scientific and Technical Information of China (English)

    Chen Dong; Chen Jing-Dong; Zhao Li-Hua; Wang Chun-Lei; Yu Ben-Hai; Shi De-Heng

    2009-01-01

    This paper investigates the equilibrium lattice parameters, heat capacity, thermal expansion coefficient, bulk modulus and its pressure derivative of LaNi5 crystal by using the first-principles plane-wave pseudopotential method in the GGA-PBE generalized gradient approximation as well as the quasi-harmonic Debye model. The dependences of bulk modulus on temperature and on pressure are investigated. For the first time it analyses the relationships between bulk modulus B and temperature T up to 1000 K, the relationship between bulk modulus B and pressure at different temperatures are worked out. The pressure dependences of heat capacity Cv and thermal expansion α atvarious temperatures are also analysed. Finally, the Debye temperatures of LaNi5 at different pressures are successfully obtained. The calculated results are in excellent agreement with the experimental data.

  10. In situ measurement of reaction volume and calculation of pH of weak acid buffer solutions under high pressure.

    Science.gov (United States)

    Min, Stephen K; Samaranayake, Chaminda P; Sastry, Sudhir K

    2011-05-26

    Direct measurements of reaction volume, so far, have been limited to atmospheric pressure. This study describes a method for in situ reaction volume measurements under pressure using a variable volume piezometer. Reaction volumes for protonic ionization of weak acid buffering agents (MES, citric acid, sulfanilic acid, and phosphoric acid) were measured in situ under pressure up to 400 MPa at 25 °C. The methodology involved initial separation of buffering agents within the piezometer using gelatin capsules. Under pressure, the volume of the reactants was measured at 25 °C, and the contents were heated to 40 °C to dissolve the gelatin and allow the reaction to occur, and cooled to 25 °C, where the volume of products was measured. Reaction volumes were used to calculate pH of the buffer solutions as a function of pressure. The results show that the measured reaction volumes as well as the calculated pH values generally quite agree with their respective theoretically predicted values up to 100 MPa. The results of this study highlight the need for a comprehensive theory to describe the pressure behavior of ionization reactions in realistic systems especially at higher pressures. PMID:21542618

  11. Formation and near-field dynamics of a wing tip vortex

    Science.gov (United States)

    Zuhal, Lavi Rizki

    2001-12-01

    The search for a more efficient method to destroy aircraft trailing vortices requires a good understanding of the early development of the vortices. For that purpose, an experimental investigation has been conducted to study the formation and near-field dynamics of a wing tip vortex. Two versions of the Digital Particle Image Velocimetry (DPIV) technique were used in the studies. Planar DPIV was used to obtain velocity fields adjacent to the wing surface. Stereoscopic DPIV, which allows instantaneous measurements of all three components of velocity within a planar slice, was used to measure velocity fields behind the wing. The trailing vortex was produced by a rectangular half-wing model with an NACA 0012 profile. All measurements were made at Reynolds number, based on chord length, of 9040. The present study has found that the wing sheds multiple vortices. A structure that closely resembles a wing tip vortex is first observed on the suction side of the wing near the tip at the mid-chord section of the wing. At the trailing edge of the wing, a smaller vortex with an opposite sense of rotation is observed next to the tip vortex. In addition to the two vortices, two vortex layers with opposite sense of rotation, one on the pressure side and one on the suction side, are apparent at the trailing edge. Farther downstream, most of the vorticity in the vortex layer, with the same sense of rotation as the tip vortex, rolls up into the wing tip vortex. The vortices, with opposite sense of rotation, break up into smaller vortices which orbit around the tip vortex. At least one relatively strong satellite vortex appears in some of the instantaneous fields. The studies found that the interaction of the tip vortex and satellite vortices give rise to the unsteady motion of the wing tip vortex. In addition, the studies also examined the effects of the boundary layer and the tip geometry to the strength and motion of the trailing vortex.

  12. A mapping relationship based near-field acoustic holography with spherical fundamental solutions for Helmholtz equation

    Science.gov (United States)

    Wu, Haijun; Jiang, Weikang; Zhang, Haibin

    2016-07-01

    In the procedure of the near-field acoustic holography (NAH) based on the fundamental solutions for Helmholtz equation (FS), the number of FS and the measurement setup to obtain their coefficients are two crucial issues to the successful reconstruction. The current work is motivated to develop a framework for the NAH which supplies a guideline to the determination of the number of FS as well as an optimized measurement setup. A mapping relationship between modes on surfaces of boundary and hologram is analytically derived by adopting the modes as FS in spherical coordinates. Thus, reconstruction is converted to obtain the coefficients of participant modes on holograms. In addition, an integral identity is firstly to be derived for the modes on convex surfaces, which is useful in determining the inefficient or evanescent modes for acoustic radiation in free space. To determine the number of FS adopted in the mapping relationship based NAH (MRS-based NAH), two approaches are proposed to supply reasonable estimations with criteria of point-wise pressure and energy, respectively. A technique to approximate a specific degree of mode on patches by a set of locally orthogonal patterns is explored for three widely used holograms, such as planar, cylindrical and spherical holograms, which results in an automatic determinations of the number and position of experimental setup for a given tolerance. Numerical examples are set up to validate the theory and techniques in the MRS-based NAH. Reconstructions of a cubic model demonstrate the potential of the proposed method for regular models even with corners and shapers. Worse results for the elongated cylinder with two spherical caps reveal the deficiency of the MRS-based NAH for irregular models which is largely due to the adopted modes are FS in spherical coordinates. The NAH framework pursued in the current work provides a new insight to the reconstruction procedure based on the FS in spherical coordinates.

  13. Ab Initio Calculations of Elastic Constants of Li2O under Pressure

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Feng; CHEN Xiang-Rong; JI Guang-Fu; MENG Chuan-Min

    2006-01-01

    @@ We investigate the equilibrium lattice constant, bulk modulus, elastic constants and Debye temperature of Li2 O under pressure by using ab initio unrestricted Hartree-Fock (HF) linear combination of atomic orbital (LCAO) periodic approach. The obtained results at zero pressure are well consistent with the available experimental data and other theoretical results. It is found that the elastic constants C11, C12 and C44 and bulk modulus B increase monotonously as pressure increases. Also, the anisotropy will weaken and the Debye temperature will rise with pressure increasing.

  14. Investigation of structure and hydrogen bonding of superhydrous phase B (HT) under pressure using first-principles density functional calculations

    Science.gov (United States)

    Poswal, H. K.; Sharma, Surinder M.; Sikka, S. K.

    2010-03-01

    High-pressure behaviour of superhydrous phase B (high temperature; HT) of Mg10Si3O14(OH)4 (Shy B) is investigated with the help of density functional theory-based first-principles calculations. In addition to the lattice parameters and equation of state, we use these calculations to determine the positional parameters of atoms as a function of pressure. Our results show that the compression induced structural changes involve cooperative distortions in the full geometry of the hydrogen bonds. The bond-bending mechanism proposed by Hofmeister et al. (Vibrational spectra of dense hydrous magnesium silicates at high pressure: Importance of the hydrogen bond angle, Am. Miner. 84 (1999), pp. 454-464) for hydrogen bonds to relieve the heightened repulsion due to short H- - -H contacts is not found to be effective in Shy B. The calculated O-H bond contraction is consistent with the observed blue shift in the stretching frequency of the hydrogen bond. These results establish that one can use first-principles calculations to obtain reliable insights into the pressure-induced bonding changes of complex minerals.

  15. Calculation Analysis of Pressure Wave Velocity in Gas and Drilling Mud Two-Phase Fluid in Annulus during Drilling Operations

    Directory of Open Access Journals (Sweden)

    Yuanhua Lin

    2013-01-01

    Full Text Available Investigation of propagation characteristics of a pressure wave is of great significance to the solution of the transient pressure problem caused by unsteady operations during management pressure drilling operations. With consideration of the important factors such as virtual mass force, drag force, angular frequency, gas influx rate, pressure, temperature, and well depth, a united wave velocity model has been proposed based on pressure gradient equations in drilling operations, gas-liquid two-fluid model, the gas-drilling mud equations of state, and small perturbation theory. Solved by adopting the Runge-Kutta method, calculation results indicate that the wave velocity and void fraction have different values with respect to well depth. In the annulus, the drop of pressure causes an increase in void fraction along the flow direction. The void fraction increases first slightly and then sharply; correspondingly the wave velocity first gradually decreases and then slightly increases. In general, the wave velocity tends to increase with the increase in back pressure and the decrease of gas influx rate and angular frequency, significantly in low range. Taking the virtual mass force into account, the dispersion characteristic of the pressure wave weakens obviously, especially at the position close to the wellhead.

  16. Temperature and pressure effects on GFP mutants: explaining spectral changes by molecular dynamics simulations and TD-DFT calculations.

    Science.gov (United States)

    Jacchetti, Emanuela; Gabellieri, Edi; Cioni, Patrizia; Bizzarri, Ranieri; Nifosì, Riccardo

    2016-05-14

    By combining spectroscopic measurements under high pressure with molecular dynamics simulations and quantum mechanics calculations we investigate how sub-angstrom structural perturbations are able to tune protein function. We monitored the variations in fluorescence output of two green fluorescent protein mutants (termed Mut2 and Mut2Y, the latter containing the key T203Y mutation) subjected to pressures up to 600 MPa, at various temperatures in the 280-320 K range. By performing 150 ns molecular dynamics simulations of the protein structures at various pressures, we evidenced subtle changes in conformation and dynamics around the light-absorbing chromophore. Such changes explain the measured spectral tuning in the case of the sizable 120 cm(-1) red-shift observed for pressurized Mut2Y, but absent in Mut2. Previous work [Barstow et al., Proc. Natl. Acad. Sci. U. S. A., 2008, 105, 13362] on pressure effects on GFP also involved a T203Y mutant. On the basis of cryocooling X-ray crystallography, the pressure-induced fluorescence blue shift at low temperature (77 K) was attributed to key changes in relative conformation of the chromophore and Tyr203 phenol ring. At room temperature, however, a red shift was observed at high pressure, analogous to the one we observe in Mut2Y. Our investigation of structural variations in compressed Mut2Y also explains their result, bridging the gap between low-temperature and room-temperature high-pressure effects. PMID:27102429

  17. Modeling of the 2011 Tohoku Near-field Tsunami from Finite-fault Inversion of Seismic Waves

    Science.gov (United States)

    Yamazaki, Y.; Cheung, K.; Lay, T.

    2012-12-01

    The Mw 9.0 March 11, 2011 Tohoku earthquake ruptured the megathrust fault offshore of northeastern Honshu and generated a devastating near-field tsunami that caused over 24,000 casualties in Japan. While both the earthquake and tsunami caused extensive infrastructure damage in the region, most of the casualties were caused by inundation of coastal towns and villages. The extensive global seismic networks, dense geodetic instruments, well-positioned water level stations, and comprehensive post-event surveys along the northeast Japan coasts provide datasets of unprecedented quality and coverage for investigation of the tsunami source mechanism and near-field wave characteristics. We utilize the shock-capturing, dispersive wave model NEOWAVE (Non-hydrostatic Evolution of Ocean WAVEs) to reconstruct the tsunami from a finite-fault solution based on teleseismic P-wave inversion. The depth-integrated model describes dispersive waves through non-hydrostatic pressure and vertical velocity, which also account for tsunami generation from time histories of seafloor deformation and transfer of kinetic energy to the water mass. These model capabilities are important for the timing and evolution of the tsunami waves near the earthquake source. The finite-fault model produces seafloor uplift patches at the epicenter and near the trench that are crucial in reproducing the near-field tsunami recorded by coastal and deep-water buoys around the source as well as runup variation along east Japan coasts. The model tsunami allows investigation of the generation mechanism in terms of the rupture process and the ocean wave dynamics over the continental margin. A confluence of physical processes associated with the rupture and the bathymetry and topography led to the devastating impact of the 2011 Tohoku tsunami along the northeastern Japan coasts. The large slip near the trench produced a long-crested wave directed toward the continental shelf. The superposition of this long-crested wave

  18. High-pressure powder x-ray diffraction experiments and ab initio calculation of Ti3AlC2

    Science.gov (United States)

    Zhang, Haibin; Wu, Xiang; Nickel, Klaus Georg; Chen, Jixin; Presser, Volker

    2009-07-01

    The structural stability of the layered ternary carbide Ti3AlC2 was studied up to 35 GPa using x-ray diffraction with a Merrill-Basset-type diamond anvil cell and ab initio calculations. The structure (P63/mmc) was stable in the present pressure range without any phase transition. The Birch-Murnaghan equation of state was employed to fit the experimental pressure-volume date, from which the isothermal bulk modulus of Ti3AlC2 was determined as 156±5 GPa, which was also supported by theoretical results. In addition, theoretical calculations described anisotropic pressure dependences of the lattice parameters, electronic structure, and bonding properties of Ti3AlC2.

  19. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction

    Science.gov (United States)

    Wang, Le; Xu, Xiaoji G.

    2015-11-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures.

  20. Resonance hybridization and near field properties of strongly coupled plasmonic ring dimer-rod nanosystem

    Energy Technology Data Exchange (ETDEWEB)

    Koya, Alemayehu Nana; Ji, Boyu; Hao, Zuoqiang; Lin, Jingquan, E-mail: linjingquan@cust.edu.cn [School of Science, Changchun University of Science and Technology, Changchun 130022 (China)

    2015-09-21

    Combined effects of polarization, split gap, and rod width on the resonance hybridization and near field properties of strongly coupled gold dimer-rod nanosystem are comparatively investigated in the light of the constituent nanostructures. By aligning polarization of the incident light parallel to the long axis of the nanorod, introducing small split gaps to the dimer walls, and varying width of the nanorod, we have simultaneously achieved resonance mode coupling, huge near field enhancement, and prolonged plasmon lifetime. As a result of strong coupling between the nanostructures and due to an intense confinement of near fields at the split and dimer-rod gaps, the extinction spectrum of the coupled nanosystem shows an increase in intensity and blueshift in wavelength. Consequently, the near field lifespan of the split-nanosystem is prolonged in contrast to the constituent nanostructures and unsplit-nanosystem. On the other hand, for polarization of the light perpendicular to the long axis of the nanorod, the effect of split gap on the optical responses of the coupled nanosystem is found to be insignificant compared to the parallel polarization. These findings and such geometries suggest that coupling an array of metallic split-ring dimer with long nanorod can resolve the huge radiative loss problem of plasmonic waveguide. In addition, the Fano-like resonances and immense near field enhancements at the split and dimer-rod gaps imply the potentials of the nanosystem for practical applications in localized surface plasmon resonance spectroscopy and sensing.

  1. Engineering kinematic theory of the contact earth pressure and its application to the static calculation of thin quay walls

    Directory of Open Access Journals (Sweden)

    V.S. Korovkin

    2013-10-01

    Full Text Available Construction of deep-water thrust berthing structures requires using new and more perfect methods of calculation containing fewer assumptions. A version of the engineering kinematic theory of contact earth pressure in the application to the water-transport and offshore structures was suggested in the article. A dimensionless static “compression – tension” diagram of the soil, presented by curvilinear function, was used in the method. In this case, the displacement of the limit point of the diagram is determined with the account of the plastic deformation modulus in the earth contact point. Practical application of engineering theory was implemented in the proposed method of the mirroring with respect to anchored thin walls. In this method different lateral pressure profiles depending on the rated scheme were used. This method consists in three steps’ loading of anchored wall. The first stage – the normal calculation of the wall in the form of beam loaded by active earth pressure and bearing on the anchor pole and partly on the base ground. The second stage – the anchor reaction and the foundation earth reactive pressure are mirrored in the form of external loads acting on the part of the water area on the beam bearing on the backfill and foundation soil. Third stage – repeating the first external load in the form of the earth pressure profile behind the wall derived in the second calculation step. Suggested calculation as distinct from existing methods, which are using active earth pressure, defines more exactly the strains in retaining wall upward or downward.

  2. Calculation and analysis of velocity and viscous drag in an artery with a periodic pressure gradient

    Science.gov (United States)

    Alizadeh, M.; Seyedpour, S. M.; Mozafari, V.; Babazadeh, Shayan S.

    2012-07-01

    Blood as a fluid that human and other living creatures are dependent on has been always considered by scientists and researchers. Any changes in blood pressure and its normal velocity can be a sign of a disease. Whatever significant in blood fluid's mechanics is Constitutive equations and finding some relations for analysis and description of drag, velocity and periodic blood pressure in vessels. In this paper, by considering available experimental quantities, for blood pressure and velocity in periodic time of a thigh artery of a living dog, at first it is written into Fourier series, then by solving Navier-Stokes equations, a relation for curve drawing of vessel blood pressure with rigid wall is obtained. Likewise in another part of this paper, vessel wall is taken in to consideration that vessel wall is elastic and its pressure and velocity are written into complex Fourier series. In this case, by solving Navier-Stokes equations, some relations for blood velocity, viscous drag on vessel wall and blood pressure are obtained. In this study by noting that vessel diameter is almost is large (3.7 mm), and blood is considered as a Newtonian fluid. Finally, available experimental quantities of pressure with obtained curve of solving Navier-Stokes equations are compared. In blood analysis in rigid vessel, existence of 48% variance in pressure curve systole peak caused vessel blood flow analysis with elastic wall, results in new relations for blood flow description. The Resultant curve is obtained from new relations holding 10% variance in systole peak.

  3. Monopole antenna in quantitative near-field microwave microscopy of planar structures

    Science.gov (United States)

    Reznik, Alexander N.; Korolyov, Sergey A.

    2016-03-01

    We have developed an analytical model of a near-field microwave microscope based on a coaxial resonator with a sharpened tip probe. The probe interacts with a layered sample that features an arbitrary depth distribution of permittivity. The microscopic tip end with the accumulated charge is regarded as a monopole antenna radiating an electric field in near zone. The impedance of such an antenna is determined within a quasi-static approximation. The proposed model is used for calculating the sample-sensitive parameters of the microscope, specifically, resonance frequency f0 and quality factor Q0, as a function of probe-sample distance h. The theory has been verified experimentally in studies of semiconductor structures, both bulk and thin films. For measurements, we built a ˜2.1 GHz microscope with an effective tip radius of about 100 μm. The theoretical and experimental dependences f0(h) and Q0(h) were found to be in a good agreement. The developed theory underlies the method for determining sheet resistance Rsh of a semiconductor film on a dielectric substrate proposed in this article. Studies were performed on doped n-GaN films on an Al2O3 substrate. The effective radius and height of the probe determined from calibration measurements of etalon samples were used as the model fitting parameters. For etalon samples, we employed homogeneous sapphire and doped silicon plates. We also performed four-probe dc measurements of Rsh. The corresponding values for samples with Rsh > 1 kΩ were found to be 50% to 100% higher than the microwave results, which are attributed to the presence of microdefects in semiconductor films.

  4. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    Science.gov (United States)

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-11-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes.

  5. Near Field Radiation Characteristics of Implantable Square Spiral Chip Inductor Antennas for Bio-Sensors

    Science.gov (United States)

    Nessel, James A.; Simons, Rainee N.; Miranda, Felix A.

    2007-01-01

    The near field radiation characteristics of implantable Square Spiral Chip Inductor Antennas (SSCIA) for Bio-Sensors have been measured. Our results indicate that the measured near field relative signal strength of these antennas agrees with simulated results and confirm that in the near field region the radiation field is fairly uniform in all directions. The effects of parameters such as ground-plane, number of turns and microstrip-gap width on the performance of the SSCIA are presented. Furthermore, the SSCIA antenna with serrated ground plane produce a broad radiation pattern, with a relative signal strength detectable at distances within the range of operation of hand-held devices for self-diagnosis.

  6. Natural geochemical analogues of the near field of high-level nuclear waste repositories

    Energy Technology Data Exchange (ETDEWEB)

    Apps, J.A. [Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    United States practice has been to design high-level nuclear waste (HLW) geological repositories with waste densities sufficiently high that repository temperatures surrounding the waste will exceed 100{degrees}C and could reach 250{degrees}C. Basalt and devitrified vitroclastic tuff are among the host rocks considered for waste emplacement. Near-field repository thermal behavior and chemical alteration in such rocks is expected to be similar to that observed in many geothermal systems. Therefore, the predictive modeling required for performance assessment studies of the near field could be validated and calibrated using geothermal systems as natural analogues. Examples are given which demonstrate the need for refinement of the thermodynamic databases used in geochemical modeling of near-field natural analogues and the extent to which present models can predict conditions in geothermal fields.

  7. Optical Field Measurement of Nano-Apertures with a Scanning Near-Field Optical Microscope

    Institute of Scientific and Technical Information of China (English)

    XU Tie-Jun; XU Ji-Ying; WANG Jia; TIAN Qian

    2004-01-01

    @@ We investigate optical near-field distributions of the unconventional C-apertures and the conventional square apertures in preliminary experiment with an aperture scanning near-field optical microscope. These nano-apertures are fabricated in Au film on a glass substrate with focused ion beam technology. The experimental results indicate the uptrend of output light intensity that a C-aperture enables the intensity maximum to increase at least 10times more than a square aperture with same unit length. The measured near-field light spot sizes of C-apertureand square aperture with 200-nm unit length are 439nm × 500nm and 245nm × 216nm, respectively.

  8. Proceedings from the technical workshop on near-field performance assessment for high-level waste

    International Nuclear Information System (INIS)

    This report contains the proceedings of 'Technical workshop of near-filed performance assessment for high-level waste' held in Madrid October 15-17, 1990. It includes the invited presentations and summaries of the scientific discussions. The workshop covered several topics: * post-emplacement environment, * benchmarking of computer codes, * glass release, * spent-fuel release, * radionuclide solubility, * near-field transport processes, * coupled processes in the near-field, * integrated assessments, * sensitivity analyses and validation. There was an invited presentation on each topic followed by an extensive discussion. One of the points highlighted in the closing discussion of the workshop was the need for international cooperation in the field of near-field performance assessment. The general opinion was that this was best achieved in smaller groups discussing specific questions. (au) Separate abstracts were prepared for 9 papers in this volume

  9. Near-field properties of diffraction through a circular subwavelength-size aperture

    Institute of Scientific and Technical Information of China (English)

    Wang Zheng-Ling; Zhou Ming; Gao Chuan-Yu; Zhang Wei

    2012-01-01

    Analytical nonparaxial vectorial electric field expressions for both Gaussian beams and plane waves diffracted through a circular aperture are derived by using the vector plane angular spectrum method for the first time,which is suitable for the subwavelength aperture and the near-field region.The transverse properties of intensity distributions and their evolutions with the propagating distance,and the power transmission functions for diffracted fields containing the whole field,the evanescent field and the propagating field are investigated in detail,which is helpful for understanding the relationship between evanescent and propagating components in the near-field region and can be applied to apertured near-field scanning optical microscopy.

  10. Near-field lithography on the azobenzene polymer liquid crystal films

    Institute of Scientific and Technical Information of China (English)

    Douguo Zhang; Jian Liu; Zebo Zhang; Li Cao; Anlian Pan; Pei Wang; Yonghua Lu; Ming Bai; Jun Yang; Lin Tang; Jiangying Zhang; Hai Ming; Qijin Zhang

    2005-01-01

    @@ In this article, we reported near-field research on azobenzene polymer liquid crystal films using scanning near-field optical microscopy (SNOM). Optical writing and subsequently topographic reading of the patterns with subwavelength resolution were carried out in our experiments. Nanometer scale dots and lines were successfully fabricated on the films and the smallest dot diameter is about 120 nm. The width of the line fabricated is about 250 nm. This method is also a choice for nanolithography. The mechanism of the surface deformation on the polymer films was briefly analyzed from the viewpoint of gradient force in the optical near field. The intensity distribution of the electric field near the tip aperture was numerically simulated using finite-difference time-domain (FDTD) method and the numerical simulation results were consistent with the experimental results.

  11. High energy photoelectron emission from gases using plasmonics enhanced near-fields

    CERN Document Server

    Ciappina, M F; Guichard, R; Pérez-Hernández, J A; Roso, L; Arnold, M; Siegel, T; Zaïr, A; Lewenstein, M

    2013-01-01

    We study theoretically the photoelectron emission in noble gases using plasmonic enhanced near-fields. We demonstrate that these fields have a great potential to generate high energy electrons by direct mid-infrared laser pulses of the current femtosecond oscillator. Typically, these fields appear in the surroundings of plasmonic nanostructures, having different geometrical shape such as bow-ties, metallic waveguides, metal nanoparticles and nanotips, when illuminated by a short laser pulse. In here, we consider metal nanospheres, in which the spatial decay of the near-field of the isolated nanoparticle can be approximated by an exponential function according to recent attosecond streaking measurements. We establish that the strong nonhomogeneous character of the enhanced near-field plays an important role in the above threshold ionization (ATI) process and leads to a significant extension in the photoelectron spectra. In this work, we employ the time dependent Schr\\"odinger equation in reduced dimensions to ...

  12. Optical probing of sample heating in scanning near-field experiments with apertured probes

    International Nuclear Information System (INIS)

    We have used the inherent thermochromism of conjugated polymers to investigate substrate heating effects in scanning near-field experiments with metal-coated 'apertured' probes. Chemically etched and pulled fibers were used to provide near-field excitation of fully converted films of poly(p-phenylene vinylene), PPV, and of poly(4,4'-diphenylene diphenylvinylene). We detect no significant blueshift of the photoluminescence spectra generated with near-field excitation, in comparison to those collected with far-field excitation. We conclude that polymer heating in the region contributing to the luminescence is less than 40 K. We also demonstrate that thermolithography of the PPV precursor is not significant by comparing UV (325 nm) and red (670 nm) illumination

  13. Near-field mapping of plasmonic antennas by multiphoton absorption in poly(methyl methacrylate).

    Science.gov (United States)

    Volpe, Giorgio; Noack, Monika; Aćimović, Srdjan S; Reinhardt, Carsten; Quidant, Romain

    2012-09-12

    Mapping the optical near-field response around nanoantennas is a challenging yet indispensable task to engineer light-matter interaction at the nanometer scale. Recently, photosensitive molecular probes, which undergo morphological or chemical changes induced by the local optical response of the nanostructures, have been proposed as a handy alternative to more cumbersome optical and electron-based techniques. Here, we report four-photon absorption in poly(methyl methacrylate) (PMMA) as a very promising tool for nanoimaging the optical near-field around nanostructures over a broad range of near-infrared optical wavelengths. The high performance of our approach is demonstrated on single-rod antennas and coupled gap antennas by comparing experimental maps with 3D numerical simulations of the electric near-field intensity.

  14. Electromagnetic Simulation of the Near-Field Distribution around a Wind Farm

    Directory of Open Access Journals (Sweden)

    Shang-Te Yang

    2013-01-01

    Full Text Available An efficient approach to compute the near-field distribution around and within a wind farm under plane wave excitation is proposed. To make the problem computationally tractable, several simplifying assumptions are made based on the geometry problem. By comparing the approximations against full-wave simulations at 500 MHz, it is shown that the assumptions do not introduce significant errors into the resulting near-field distribution. The near fields around a 3×3 wind farm are computed using the developed methodology at 150 MHz, 500 MHz, and 3 GHz. Both the multipath interference patterns and the forward shadows are predicted by the proposed method.

  15. Noise analysis for near field 3-D FM-CW radar imaging systems

    Energy Technology Data Exchange (ETDEWEB)

    Sheen, David M.

    2015-06-19

    Near field radar imaging systems are used for several applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit the performance in several ways including reduction in system sensitivity and reduction of image dynamic range. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

  16. First-Principle Calculations of Elastic Properties of Wurtzite-Type Aluminum Nitride Under Pressure

    Institute of Scientific and Technical Information of China (English)

    REN Ji-Rong; WANG Yong-Liang; WEI Shao-Wen; CUI Hong-Ling; XU Dong-Hui; YU Bai-Ru; DUAN Yi-Shi; CHEN Xiang-Rong

    2008-01-01

    The elastic properties of the wurtzite-type aluminum nitride (w-AIN) are investigated by ab initio plane-wave pseudopotential density functional theory method. The pressure dependences of the normalized primitive cell volume V/V0, the elastic constants cij, the aggregate elastic modulus (B, G, E), the Poisson's ratio (v), and the Debye temperature θD are successfully obtained. From the elastic constants of the w-A1N under pressure, we find that the w-AIN should be unstable at higher pressure than 61.33 GPa.

  17. High-pressure crystal structures of TaAs from first-principles calculations

    Science.gov (United States)

    Lu, Mingchun; Guo, Yanan; Zhang, Miao; Liu, Hanyu; Tse, John S.

    2016-08-01

    In this work, we systematically studied the phase transition of TaAs under high pressures and reported three high-pressure structures P-6m2 (hexagonal, stable at 13-32 GPa), P21/c (monoclinic, stable at 32-103 GPa) and Pm-3m (cubic, stable above 103 GPa), by using particle swarm optimization in combination with first principles electronic structure methodology. All predicted structures are dynamically stable, since there is no imaginary mode to be found in the whole Brillouin zone. At high pressures, the TaAs was found to become superconductor with the superconducting critical temperature of ~1 K at about 100 GPa.

  18. Thermodynamic properties of cubic ZrC under high pressure from first-principles calculations

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The elastic and thermodynamic properties of Zirconium carbide (ZrC) are investigated by ab initio plane-wave pseudopotential density function theory method. The obtained lattice constant, elastic constant and bulk modulus B are consistent with the experimental and theoretical data. Through the quasi-harmonic Debye model, the dependences of the normalized volume V/V0 and the bulk modulus B on pressure P, as well as the specific heat CV on the temperature T are obtained successfully. The relationships of the thermal expansion α with temperature and pressure are also investigated, which indicate the temperature hardly has any effect on the thermal expansion α at high pressure.

  19. First-principles calculations for elastic properties of rutile TiO2 under pressure

    Institute of Scientific and Technical Information of China (English)

    Zhu Jun; Yu Jing-Xin; Wang Yan-Ju; Chen Xiang-Rong; Jing Fu-Qian

    2008-01-01

    This paper studies the equilibrium structure parameters "and the dependences of the elastic properties on pressure for rutile TiO2 by using the Cambridge Serial Total Energy Package (CASTEP) program in the frame of density functionaltheory. The obtained equilibrium structure parameters, bulk modulus B0 and its pressure derivative B'0 are in good agreement with experiments and the theoretical results. The six independent elastic constants of rutile TiO2 under pressure are theoretically investigated for the first time. It is found that, as pressure increases, the elastic constants C11,C33, C66, C12 and C13 increase, the variation of elastic constant C44 is not obvious and the anisotropy will weaken.

  20. Near-Field Ultrasonic Phased Array Deflection Focusing Based CFRP Wing Box Structural Health Monitoring

    OpenAIRE

    Yajie Sun; Yonghong Zhang; Chengshan Qian; Zijia Zhang

    2013-01-01

    Near-field ultrasonic phased array theory is researched and utilized in the carbon-fiber wing box to identify the damage in the structure. Near-field ultrasonic phased array based structural health monitoring is researched to overcome the limitation of the far-field ultrasonic phased array in monitoring scope. The time delay of the theory and the process of the damage identification method are researched in detail. The recognition result is shown in a mapped image. The proposed method is appl...

  1. Temporal and Spectral Properties of Subcycle THz Pulses in Near-Field Zone

    Institute of Scientific and Technical Information of China (English)

    YANG Yu-Ping; YAN Wei; XU Xin-Long; SHI Yu-Lei; WANG Li

    2005-01-01

    @@ In a novel generation and detection configuration of terahertz (THz) radiation, we investigate experimentally and numerically the properties of sub-cycle THz pulses in the near field. It is found that the sub-cycle THz pulses experience significant spectral and temporal deformation in the near-field zone. The variations of both the pulse waveform and spectral distribution of the THz electric field are clearly observed in our experiments when the spot size of source is changed. Numerical simulations based on Gaussian distribution are performed to explain the details of the data and lead to an excellent agreement with the experimental results.

  2. Properties of Speckle Intensities in Near-Field Optical Regions by Numerical Solutions of Wave Equations

    Institute of Scientific and Technical Information of China (English)

    CHENG Chuan-Fu; REN Xiao-Rong; LIU Chun-Xiang; ZHANG Ning-Yu; TENG Shu-Yun; XU Zhi-Zhan

    2004-01-01

    @@ Starting from the electromagnetic wave equations and boundary conditions and using Green's integral theorem,we implement the rigorous numerical solutions of the speckle field produced by scattering of dielectric random surfaces in the optical near-field. The average sizes of speckle granules are enlarged very quickly with the increase of the distance in the range less than a wavelength. It is found that the speckle contrast in the near-field and in the neighbourhood region is inversely proportional to the square of lateral correlation length at its large values and linearly decreases with the roughness exponent.

  3. A Novel Metal-Dielectric Antenna for Terahertz Near-Field Imaging

    OpenAIRE

    N. Klein; Lahl, P.; Poppe, U.; Kadlec, F.; Kuzel, P.

    2005-01-01

    We present an antenna-based approach to near-field imaging and spectroscopy, which can be used for both continuous-wave and pulsed broadband electromagnetic radiations from microwave to terahertz frequencies. Our near-field antenna consists. of a rectangular-shaped block of low-loss dielectric material sharpened to a pyramidal tip which is partially metallized and terminated by a micron-sized plane facet. At this facet the entire energy of the incident wave is concentrated as a very high but ...

  4. Optical near-field lithography on hydrogen-passivated silicon surfaces

    DEFF Research Database (Denmark)

    Madsen, Steen; Müllenborn, Matthias; Birkelund, Karen;

    1996-01-01

    optical near field, were observed after etching in potassium hydroxide. The uncoated fibers can also induce oxidation without light exposure, in a manner similar to an atomic force microscope, and linewidths of 50 nm have been achieved this way. (C) 1996 American Institute of Physics.......We report on a novel lithography technique for patterning of hydrogen-passivated amorphous silicon surfaces. A reflection mode scanning near-field optical microscope with uncoated fiber probes has been used to locally oxidize a thin amorphous silicon layer. Lines of 110 nm in width, induced by the...

  5. Control of scattering from probes for near-field antenna measurements by use of skirt

    DEFF Research Database (Denmark)

    Frandsen, A.; Pivnenko, Sergiy; Breinbjerg, Olav

    2004-01-01

    A novel approach to reducing the multiple reflections between the test antenna and the probe in near-field antenna measurements is proposed. Instead of absorbers, this approach makes use of a skirt on the probe to shield against the mounting structure behind the probe.......A novel approach to reducing the multiple reflections between the test antenna and the probe in near-field antenna measurements is proposed. Instead of absorbers, this approach makes use of a skirt on the probe to shield against the mounting structure behind the probe....

  6. Near-field ablation threshold of cellular samples at mid-IR wavelengths

    CERN Document Server

    Raghu, Deepa; Gamari, Benjamin; Reeves, M E

    2012-01-01

    We report the near-field ablation of material from cellulose acetate coverslips in water and my- oblast cell samples in growth media, with a spot size as small as 1.5 {\\mu}m under 3 {\\mu}m wavelength radiation. The power dependence of the ablation process has been studied and comparisons have been made to models of photomechanical and plasma-induced ablation. The ablation mechanism is mainly dependent on the acoustic relaxation time and optical properties of the materials. We find that for all near-field experiments, the ablation thresholds are very high, pointing to plasma-induced ablation as the dominant mechanism.

  7. CdSe-single-nanoparticle based active tips for near-field optical microscopy

    CERN Document Server

    Chevalier, N; Woehl, J C; Reiss, P; Bleuse, J; Chandezon, F; Huant, S

    2005-01-01

    We present a method to realize active optical tips for use in near-field optics that can operate at room temperature. A metal-coated optical tip is covered with a thin polymer layer stained with CdSe nanocrystals or nanorods at low density. The time analysis of the emission rate and emission spectra of the active tips reveal that a very small number of particles - possibly down to only one - can be made active at the tip apex. This opens the way to near-field optics with a single inorganic nanoparticle as a light source.

  8. Polarization contrast in reflection near-field optical microscopy with uncoated fibre tips

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Langbein, Wolfgang; Hvam, Jørn Märcher

    1999-01-01

    Using cross-hatched, patterned semiconductor surfaces and round 20-nm-thick gold pads on semiconductor wafers, we investigate the imaging characteristics of a reflection near-field optical microscope with an uncoated fibre tip for different polarization configurations and light wavelengths....... Is is shown that cross-polarized detection allows one to effectively suppress far-field components in the detected signal and to realise imaging of optical contrast on the sub-wavelength scale. The sensitivity window of our microscope, i.e. the scale on which near-field optical images represent mainly optical...

  9. Millimeter-wave near-field imaging with bow-tie antennas.

    Science.gov (United States)

    Omarouayache, Rachid; Payet, Pierre; Raoult, Jérémy; Chusseau, Laurent

    2015-05-01

    A near-field reflectometry experiment operating at 60 GHz is built in view of material and circuit inspection. Experiments are always obtained in constant height mode of operation. The bow-tie near-field probe acts mostly as a linearly-polarized electric dipole and allows strongly subwavelength resolution of ≈ λ/130. Its interaction with sample is shown polarization dependent and sensitive to both the local topography and the local dielectric constant or metal conductivity. Resonant and non-resonant probes are both evaluated. PMID:25969302

  10. Near field and altered zone environmental report Volume I: technical bases for EBS design

    Energy Technology Data Exchange (ETDEWEB)

    Wilder, D. G., LLNL

    1997-08-01

    This report presents an updated summary of results for the waste package (WP) and engineered barrier system (EBS) evaluations, including materials testing, waste-form characterization, EBS performance assessments, and near-field environment (NFE) characterization. Materials testing, design criteria and concept development, and waste-form characterization all require an understanding of the environmental conditions that will interact with the WP and EBS. The Near-Field Environment Report (NFER) was identified in the Waste Package Plan (WPP) (Harrison- Giesler, 1991) as the formal means for transmitting and documenting this information.

  11. Wideband Phase Retrieval Technique from Amplitude-Only Near-Field Data

    Directory of Open Access Journals (Sweden)

    G. D. Massa

    2008-12-01

    Full Text Available A wideband frequency behavior is demonstrated for a phaseless near-field technique of basically interferometric approach, which uses two identical probes interfering each other through a microstrip circuit and performing amplitude-only near-field measurements on a single scanning surface. The phase retrieval procedure is properly formulated to take into account the frequency dependence without changing neither the microstrip circuit nor the distance between the probes. Numerical simulations on a linear array of elementary sources are presented to validate the theoretical results.

  12. Persistent Directional Current at Equilibrium in Nonreciprocal Many-Body Near Field Electromagnetic Heat Transfer

    Science.gov (United States)

    Zhu, Linxiao; Fan, Shanhui

    2016-09-01

    We consider the consequence of nonreciprocity in near-field heat transfer by studying systems consisting of magneto-optical nanoparticles. We demonstrate that, in thermal equilibrium, a nonreciprocal many-body system in heat transfer can support a persistent directional heat current, without violating the second law of thermodynamics. Such a persistent directional heat current cannot occur in reciprocal systems, and can only arise in many-body systems in heat transfer. The use of nonreciprocity therefore points to a new regime of near-field heat transfer for the control of heat flow in the nanoscale.

  13. Thermal supercurrent in non-reciprocal many-body near field electromagnetic heat transfer

    CERN Document Server

    Zhu, Linxiao

    2016-01-01

    We consider the consequence of non-reciprocity in near-field heat transfer by studying systems consisting of magneto-optical nanoparticles. We demonstrate that in thermal equilibrium, non-reciprocal many-body system can support a persistent directional heat current, i.e. thermal supercurrent, without violating the second law of thermodynamics. Such a thermal supercurrent can not occur in reciprocal systems, and can only arise in many-body systems. The use of non-reciprocity therefore points to a new regime of near-field heat transfer for the control of heat flow in the nanoscale.

  14. Frequency-domain electromagnetic sounding with combination wave in near-field zone

    Institute of Scientific and Technical Information of China (English)

    苏发; 何继善

    1996-01-01

    By analysing the propagation law of electromagnetic wave,the distribution pattern of the field and the theory of frequency electromagnetic sounding,the physical mechanisms that make the frequency electromagnetic sounding in near-field zone difficult are discussed.Based on the theory of near source field,a new method of dual-frequency electromagnetic sounding of combination wave in near-field zone is advanced.Meanwhile,the method of measurement of fields,the definition of apparent resistivity and the numerical algorithm are approached.

  15. Near-field to far-field transition of photonic crystal fibers symmetries and interference phenomena

    CERN Document Server

    Mortensen, N A

    2002-01-01

    The transition from the near to the far field of the fundamental mode radiating out of a photonic crystal fiber is investigated experimentally and theoretically. It is observed that the hexagonal shape of the near field rotates two times by pi/6 when moving into the far field, and eventually six satellites form around a nearly gaussian far-field pattern. A semi-empirical model is proposed, based on describing the near field as a sum of seven gaussian distributions, which qualitatively explains all the observed phenomena and quantitatively predicts the relative intensity of the six satellites in the far field.

  16. The 2D Linearly Polarized Near-Field Focusing Based on Angularly Discretized Slot Arrays

    CERN Document Server

    Chen, Menglin; Ma, Zilong; Jiang, Lijun

    2014-01-01

    A 2-D near-field focusing design is proposed based on the circular slot array waveguide structures, synthesized using the array-factor theory, and demonstrated by full-wave simulations. The principle of beam-focusing is extended to the 2-D angularly discretized configuration using regular center-fed linear slots arranged in a circular pattern. By the mirror image arrangement of the slots, a linearly polarized focus in the near-field of the antenna, with negligible cross-polarization is achieved. Its beam-focusing properties are discussed in details and demonstrated by simulations.

  17. Near-field x-ray phase contrast imaging and phase retrieval algorithm

    Institute of Scientific and Technical Information of China (English)

    Zhu Hua-Feng; Xie Hong-Lan; Gao Hong-Yi; Chen Jian-Wen; Li Ru-Xin; Xu Zhi-Zhan

    2005-01-01

    Theoretical analyses of x-ray diffraction phase contrast imaging and near field phase retrieval method are presented.A new variant of the near field intensity distribution is derived with the optimal phase imaging distance and spatial frequency of object taken into account. Numerical examples of phase retrieval using simulated data are also given. On the above basis, the influence of detecting distance and polychroism of radiation on the phase contrast image and the retrieved phase distribution are discussed. The present results should be useful in the practical application of in-line phase contrast imaging.

  18. Calculating the optimum pressure and temperature for vacancy minimization from theory; Niobium is an example

    OpenAIRE

    Garai József (1951-) (építőmérnök)

    2010-01-01

    Self-resonance in the atomic vibration occurs when the average wavelength of the phonon thermal vibration is equivalent or harmonic of the diameters of the atoms. It is suggested that applying pressure at temperature corresponding to the self-resonance should effectively reduce the number of vacancies. This theoretical prediction is tested on Niobium by measuring the magnetic susceptibility of the untreated and treated samples. The applied pressure-temperature treatment increased the critical...

  19. Pressure surge in a rapid shutdown system: update of calculations by measurement results-a procedure within periodical controls

    International Nuclear Information System (INIS)

    A rapid shutdown system of a BWR consists of four tank pipes (ND 250) and two ring pipes (ND 150). The tank pipes connect three pressure tanks with the ring pipes which distribute the hydraulic pressure to the so-called scram pipes. The scram pipes drive the steering rods. Beyond the normal operation conditions shutdowns represent the main loading. Within the concept for periodical examinations of the rapid shutdown system different testing methods as well as calculations are established. The major portion of the welding seams in this system is examined by non-destructive testing like ultrasonic measurement. For completion of the information about the integrity of the piping system mechanical measurements as well as numerical calculations are carried out. At first measurements were performed during pressure surge at boundary conditions (20 bar reactor pressure) which are expected to result in increased loading for the system. The measurements are focused on positions at the test pipes outside the containment because with respect to the plant experience the two ring pipes are expected to remain in their static position during pressure surge. With the measurements the real accelerations, displacements and especially strains are documented at positions which are supposed to be representative for the whole system as well as near welding seams which cannot be examined by ultrasonic measurements. Calculations were done after the measurements. In the calculation model the complete piping with ND 250 and ND 150 is included with the different supporting facilities like fixed points at the tanks, shock absorbers, sliding contacts, transitions at the containment shell and sliding contacts of the two ring pipes. Two load cases are investigated: normal operation and pressure surge. The pressure surge loading of the pipe is input to the piping code from compatible data files of a separate hydraulic code. First a linear dynamic calculation gives some insight in the motion as well

  20. A unified equation for calculating methane vapor pressures in the CH4-H2O system with measured Raman shifts

    Science.gov (United States)

    Lu, W.; Chou, I.-Ming; Burruss, R.C.; Song, Y.

    2007-01-01

    A unified equation has been derived by using all available data for calculating methane vapor pressures with measured Raman shifts of C-H symmetric stretching band (??1) in the vapor phase of sample fluids near room temperature. This equation eliminates discrepancies among the existing data sets and can be applied at any Raman laboratory. Raman shifts of C-H symmetric stretching band of methane in the vapor phase of CH4-H2O mixtures prepared in a high-pressure optical cell were also measured at temperatures between room temperature and 200 ??C, and pressures up to 37 MPa. The results show that the CH4 ??1 band position shifts to higher wavenumber as temperature increases. We also demonstrated that this Raman band shift is a simple function of methane vapor density, and, therefore, when combined with equation of state of methane, methane vapor pressures in the sample fluids at elevated temperatures can be calculated from measured Raman peak positions. This method can be applied to determine the pressure of CH4-bearing systems, such as methane-rich fluid inclusions from sedimentary basins or experimental fluids in hydrothermal diamond-anvil cell or other types of optical cell. ?? 2007 Elsevier Ltd. All rights reserved.

  1. Theoretical Calculation of the Real Vapor Pressure of Al during ISM Processing of Ni-xAl (at.pct)(x=25~50) Alloy

    Institute of Scientific and Technical Information of China (English)

    Jingjie GUO; Guizhong LIU; Yanqing SU; Jun JIA; Hengzhi FU

    2004-01-01

    A new model was established to calculate the real vapor pressure of Al in the molten Ni-xAI (at. Pct) (x=25~50)alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature on the real vapor pressure of Al in the vacuum chamber were analyzed. Because of the impeding effect of the real vapor pressure on the evaporation loss rate, within a short time (less than 10 s), the real vapor pressure tends to a constant value.When the chamber pressure is less than the saturated vapor pressure of Al, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is higher than the saturated vapor pressure, the real vapor pressure of Al approaches to the saturated vapor pressure of Al of the same condition.

  2. Large eddy simulation of the near-field vortex dynamics in starting square jet transitioning into steady state

    Science.gov (United States)

    Ghasemi, A.; Roussinova, V.; Barron, R. M.; Balachandar, R.

    2016-08-01

    Large eddy simulation (LES) is carried out to study the vortex dynamics in the near-field of a starting turbulent square jet as well as its evolution into a developed steady jet. Simulations are conducted at Reynolds numbers (Re = UjD/υ) of 8000 and 45 000 based on the nozzle hydraulic diameter (" separators=" D ) and jet velocity (Uj). A Reynolds stress model was used to simulate the internal flow in the nozzle which provided the inlet conditions for the LES of the jet. To validate the simulations, turbulence statistics are compared with experimental results available for a steady square jet. Evaluation of the probability density function, skewness, and flatness of the centerline streamwise velocity (Uc) shows deviation from the Gaussian distribution in the near-field. Evolution of the self-induced deformation of the leading vortex ring is investigated to further clarify the role of axis-switching. The axis-switching is initiated earlier at low Reynolds number while the completion of the axis-switching process occurred at the same dimensionless time for both Reynolds numbers. The role of pressure distribution on vortex ring deformation is investigated. It is shown that the influence of pressure-induced azimuthal instability tends to deform a two-dimensional vortex ring topology into a three-dimensional one and revert back to a two-dimensional character again. The break-down and diffusion of the tip of the vortex are also studied. Evolution of the shear layer from a starting jet to a developed jet is studied in terms of the vorticity field. For a starting jet, entrainment is shown to occur in the presence of corner hairpin vortices.

  3. FP-APW+lo calculations of the electronic and optical properties of alkali metal sulfides under pressure

    International Nuclear Information System (INIS)

    The electronic and optical properties of M2S (M = Li, Na, K and Rb) compounds in the cubic antifluorite structure have been calculated, using a full relativistic version of the full-potential augmented plane-wave plus local orbitals method based on density functional theory, within both the local density approximation (LDA) and the generalized gradient approximation (GGA). Moreover, the Engel-Vosko GGA formalism (EV-GGA) is applied so as to optimize the corresponding potential for band structure calculations. The calculated equilibrium lattices and bulk moduli are in good agreement with the available data. Band structure, density of states, electron charge density and pressure coefficients of energy gaps are given. Results obtained for band structure using EV-GGA are larger than those with LDA and GGA. It is found that the spin-orbit coupling lifts the triple degeneracy at the Γ point and the double degeneracy at the X point. The analysis of the electron charge density shows that the M-S bonds have a significant ionic character. The complex dielectric functions ε2(ω) for alkali metal sulfides were calculated for radiation up to 30 eV and the assignment of the critical points to the band structure energy differences at various points of the Brillouin zone was made. The pressure and volume dependence of the static dielectric constant and the refractive index are calculated.

  4. Calculation of a leak in the bottom of a bwr-pressure vessel using THYDE-B1

    International Nuclear Information System (INIS)

    The present report describes the modelling of a boiling water reactor of the Gemeinschaftskraftwerk Tullnerfeld (GKT) plant type. The corresponding input data set for the Japanese computer code THYDE-B1 allows the simulation of the thermohydraulic transient within the reactor coolant system during a loss of coolant accident. The initiating event 'Leak in the Reactor Pressure Vessel Bottom' has been calculated as an application exercise. The results are discussed using graphic representation, where one should be aware that the calculated data do not correspond with any specific plant configuration of the boiling water reactor generic design. 1 ref., 7 figs. (Author)

  5. Mean-field potential calculations of high-pressure equation of state for BeO

    Institute of Scientific and Technical Information of China (English)

    Zhang Qi-Li; Zhang Ping; Song Hai-Feng; Liu Hai-Feng

    2008-01-01

    A systematic study of the Hugoniot equation of state, phase transition, and the other thermodynamic properties including the Hugoniot temperature, the electronic and ionic heat capacities, and the Griineisen parameter for shockcompressed BeO, has been carried out by calculating the total free energy. The method of calculations combines first-principles treatment for 0 K and finite-T electronic contribution and the mean-field-potential approach for the vibrational contribution of the lattice ion to the total energy. Our calculated Hugoniot is in good agreement with the experimental data.

  6. Thermodynamic properties of cubic ZrC under high pressure from first-principles calculations

    Institute of Scientific and Technical Information of China (English)

    ZHU Jun; ZHU Bo; QU JianYing; GOU QingQuan; CHEN Fang

    2009-01-01

    The elastic and thermodynamic properties of Zirconium carbide (ZrC) are investigated by ab initio plane-wave pseudopotential density function theory method. The obtained lattice constant, elastic constant and bulk modulus B are consistent with the experimental and theoretical data. Through the quasi-harmonic Debye model, the dependences of the normalized volume V/V0 and the bulk modulus B on pressure P, as well as the specific heat CV on the temperature T are obtained successfully. The rela-tionships of the thermal expansion α with temperature and pressure are also investigated, which indi-cate the temperature hardly has any effect on the thermal expansion α at high pressure.

  7. Characterization of aniosotropic nano-particles by using depolarized dynamic light scattering in the near field

    NARCIS (Netherlands)

    Brogioli, D.; Salerno, D.; Cassina, V.; Sacanna, S.; Philipse, A.P.; Croccolo, F.; Mantegazza, F.

    2009-01-01

    Light scattering techniques are widely used in many fields of condensed and soft matter physics. Usually these methods are based on the study of the scattered light in the far field. Recently, a new family of near field detection schemes has been developed, mainly for the study of small angle light

  8. Near-field light focusing by wavelength-sized dielectric spheroids for photovoltaic applications

    OpenAIRE

    Moura Dias Mendes, Manuel Joao de; Tobías Galicia, Ignacio; Martí Vega, Antonio; Luque López, Antonio

    2011-01-01

    We explore the near-field concentration properties of dielectric spheroidal scatterers with sizes close to the wavelength, using an analytical separation-of-variables method. Such particles act as mesoscopic lenses whose physical parameters are optimized here for maximum scattered light enhancement in photovoltaic applications.

  9. Three-dimensional mapping of optical near field of a nanoscale bowtie antenna.

    Science.gov (United States)

    Guo, Rui; Kinzel, Edward C; Li, Yan; Uppuluri, Sreemanth M; Raman, Arvind; Xu, Xianfan

    2010-03-01

    Ridge nanoscale aperture antennas have been shown to be a high transmission nanoscale light source. They provide a small, polarization-dependent near-field optical spot with much higher transmission efficiency than circularly-shaped apertures with similar field confinement. This provides significant motivations to understand the electromagnetic fields in the immediate proximity to the apertures. This paper describes an experimental three-dimensional optical near-field mapping of a bowtie nano-aperture. The measurements are performed using a home-built near-field scanning optical microscopy (NSOM) system. An aluminum coated Si(3)N(4) probe with a 150 nm hole at the tip is used to collect optical signals. Both contact and constant-height scan (CHS) modes are used to measure the optical intensity at different longitudinal distances. A force-displacement curve is used to determine the tip-sample separation distance allowing the optical intensities to be mapped at distances as small as 50 nm and up to micrometer level. The experimental results also demonstrate the polarization dependence of the transmission through the bowtie aperture. Numerical simulations are also performed to compute the aperture's electromagnetic near-field distribution and are shown to agree with the experimental results. PMID:20389507

  10. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements

    Science.gov (United States)

    de Graaf, S. E.; Danilov, A. V.; Adamyan, A.; Kubatkin, S. E.

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 {μ V}, approaching low enough photon population (N ˜ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10-20 F/sqrt{Hz}, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy.

  11. The long term behaviour of the near-field barrier surrounding a deep underground repository

    International Nuclear Information System (INIS)

    This report describes research to identify the factors which govern or influence the long-term behaviour of the near-field of a nuclear waste repository. The near-field components include the engineered barriers and the natural rock mass although the behaviour of the rock mass is of greater significance over the long-term. The factors which govern the near-field behaviour consist of the processes which operate, and the properties or parameters of the rock mass which might be modified by them. The methods which are available for the prediction of the near-field behaviour have been identified, and the emphasis on computer based methods is noted. Summary details of generic computer techniques are provided for different process modelling requirements. An attempt is made to indicate how different processes will be important at various stages during the life of the repository and how the evaluation of performance assessment process modelling requires input from empirical models and the results of other process predictions. (Author)

  12. Fluorescence in situ hybridization on human metaphase chromosomes detected by near-field scanning optical microscopy

    NARCIS (Netherlands)

    Moers, M.H.P.; Kalle, W.H.J.; Ruiter, A.G.T.; Wiegant, J.C.A.G.; Raap, A.K.; Greve, J.; Grooth, de B.G.; Hulst, van N.F.

    1996-01-01

    Fluorescence in situ hybridization o­n human metaphase chromosomes is detected by near-field scanning optical microscopy. This combination of cytochemical and scanning probe techniques enables the localization and identification of several fluorescently labelled genomic DNA fragments o­n a single ch

  13. Polarization contrast in fluorescence scanning near-field optical microscopy in reflection

    NARCIS (Netherlands)

    Jalocha, A.; Hulst, van N.F.

    1995-01-01

    Polarization contrast is presented in fluorescence images of a Langmuir-Blodgett monolayer obtained with a scanning near-field optical microscope operated in reflection. A tapered optical fiber is used both to excite and to collect the fluorescence. The lateral resolution in the reflection fluoresce

  14. Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation.

    Science.gov (United States)

    Hermann, Peter; Hoehl, Arne; Patoka, Piotr; Huth, Florian; Rühl, Eckart; Ulm, Gerhard

    2013-02-11

    We demonstrate scanning near-field optical microscopy with a spatial resolution below 100 nm by using low intensity broadband synchrotron radiation in the IR regime. The use of such a broadband radiation source opens up the possibility to perform nano-Fourier-transform infrared spectroscopy over a wide spectral range. PMID:23481749

  15. Single molecule mapping of the optical field distribution of probes for near-field microscopy

    NARCIS (Netherlands)

    Veerman, J.A.; Garcia-Parajo, M.F.; Kuipers, L.; Hulst, van N.F.

    1999-01-01

    The most difficult task in near-field scanning optical microscopy (NSOM) is to make a high quality subwavelength aperture probe, Recently we have developed high definition NSOM probes by focused ion beam (FIB) milling. These probes have a higher brightness, better polarization characteristics, bette

  16. Hybridized plasmon modes and near-field enhancement of metallic nanoparticle-dimer on a mirror

    Science.gov (United States)

    Huang, Yu; Ma, Lingwei; Hou, Mengjing; Li, Jianghao; Xie, Zheng; Zhang, Zhengjun

    2016-07-01

    For the attractive plasmonic structure consisting of metal nanoparticles (NPs) on a mirror, the coexistence of near-field NP-NP and NP-mirror couplings is numerically studied at normal incidence. By mapping their 3D surface charge distributions directly, we have demonstrated two different kinds of mirror-induced bonding dipole plasmon modes and confirmed the bonding hybridizations of the mirror and the NP-dimer which may offer a much stronger near-field enhancement than that of the isolated NP dimers over a broad wavelength range. Further, it is revealed that the huge near-field enhancement of these two modes exhibit different dependence on the NP-NP and NP-mirror hot spots, while both of their near-field resonance wavelengths can be tuned to the blue exponentially by increasing the NP-NP gaps or the NP-mirror separation. Our results here benifit significantly the fundamental understanding and practical applications of metallic NPs on a mirror in plasmonics.

  17. Near-field imaging of interference pattern of counterpropagating evanescent waves

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Bozhevolnaya, Elena A.

    1999-01-01

    It is generally accepted that measurement of of the contrast of the intensity interference pattern formed by two counterpropagating evanescent waves can be used to characterize the resolving power of a collection near-field microscope. We argue that, if the light collected by a fiber probe...... be equal to the contrast of the interference pattern....

  18. The influence of organic materials on the near field of an intermediate level radioactive waste repository

    International Nuclear Information System (INIS)

    The influence of organic materials which are present in some intermediate level wastes on the chemistry of the near field of a radioactive waste repository is discussed. Particular attention is given to the possible formation of water soluble complexing agents as a result of the radiation field and chemical conditions. The present state of the research is reviewed. (author)

  19. RADIATION EFFECTS ON MATERIALS IN THE NEAR-FIELD OF NUCLEAR WASTE REPOSITORY

    Science.gov (United States)

    Successful, demonstrated containment of radionuclides in the near-field can greatly reduce the complexity of the performance assessment analysis of a geologic repository. The chemical durability of the waste form, the corrosion rate of the canister, and the physical and chemical ...

  20. Modal symmetries at the nanoscale : A route toward a complete vectorial near-field mapping

    NARCIS (Netherlands)

    Feber, Boris Le; Rotenberg, Nir; Van Oosten, Dries; Kuipers, L.

    2014-01-01

    We use symmetry considerations to understand and unravel near-field measurements, ultimately showing that we can spatially map three distinct fields using only two detectors. As an example, we create 2D field maps of the outof- plane magnetic field and two in-plane fields for a silicon ridge wavegui

  1. Near-field imaging of light propagation in photonic crystal waveguides: Explicit role of Bloch harmonics

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Volkov, V.S.; Søndergaard, Thomas;

    2002-01-01

    We employ a collection scanning near-field optical microscope (SNOM) to image the propagation of light at telecommunication wavelengths along straight and bent regions of silicon-on-insulator photonic crystal waveguides (PCWs) formed by removing a single row of holes in the triangular 410-nm-peri...

  2. Characterization of viscous biofuel sprays using digital imaging in the near field region

    NARCIS (Netherlands)

    Sallevelt, J.L.H.P.; Pozarlik, A.K.; Brem, G.

    2015-01-01

    The atomization of biodiesel, vegetable oil and glycerin has been studied in an atmospheric spray rig by using digital imaging (PDIA). Images of the spray were captured in the near field, just 18 mm downstream of the atomizer, and processed to automatically determine the size of both ligaments and d

  3. Induced Light Emission from Quantum Dots: The Directional Near-Field Pattern

    DEFF Research Database (Denmark)

    Iezhokin, Igor; Keller, Ole; Lozovski, Valeri

    2010-01-01

    The optical Lippmann-Schwinger equation, supplemented by the microscopic conductivity tensor, is used to establish a near-field radiation theory for a mesoscopic particle. The present theory deviates from previous ones in that it allows one to take into account the finite size of the particle in ...

  4. Hybridized plasmon modes and near-field enhancement of metallic nanoparticle-dimer on a mirror

    Science.gov (United States)

    Huang, Yu; Ma, Lingwei; Hou, Mengjing; Li, Jianghao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    For the attractive plasmonic structure consisting of metal nanoparticles (NPs) on a mirror, the coexistence of near-field NP-NP and NP-mirror couplings is numerically studied at normal incidence. By mapping their 3D surface charge distributions directly, we have demonstrated two different kinds of mirror-induced bonding dipole plasmon modes and confirmed the bonding hybridizations of the mirror and the NP-dimer which may offer a much stronger near-field enhancement than that of the isolated NP dimers over a broad wavelength range. Further, it is revealed that the huge near-field enhancement of these two modes exhibit different dependence on the NP-NP and NP-mirror hot spots, while both of their near-field resonance wavelengths can be tuned to the blue exponentially by increasing the NP-NP gaps or the NP-mirror separation. Our results here benifit significantly the fundamental understanding and practical applications of metallic NPs on a mirror in plasmonics. PMID:27418039

  5. Room-temperature near-field reflection spectrocopy of semiconductor nanostructures

    DEFF Research Database (Denmark)

    Langbein, Wolfgang; Hvam, Jørn Märcher; Madsen, Steen

    1999-01-01

    We investigate the properties of near-field reflection spectroscopy in different polarization and detection modes using uncoated fiber probes. The results show, that cross-polarized detection suppresses to a large extent far-field contributions. Using the fiber dithering as a modulation source fo...

  6. Neutronic modelling of the reflector for the calculation of pressurized water reactors: application to EPR

    International Nuclear Information System (INIS)

    This PhD Thesis aims to achieve a method for the modelling of the reflector surrounding the core for neutronics core calculations. This method should consider the EPR reactor specificities (steel reflector) and the increased demand in precision. In neutronics core calculations, the reflector can be represented either by albedos boundary conditions (current ratios) or by one or several media, surrounding the core, characterised by homogenized parameters. Those parameters (cross sections and diffusion coefficients) should be obtained using equivalence so that they allow a good reproduction of the reference albedos in a representative situation. During this PhD, such an equivalence method has been developed in the APOLLO-2 code with the minimization of a functional of the differences between the reference albedos and those computed with the equivalent parameters. Because of the positiveness constraints, a local minimization, such as Newton-like methods, is not always possible and we have therefore also implemented a Particle Swarm Optimization Algorithm for more than two energy groups' problems. The parameters obtained have been used in two dimensions EPR core calculations with the CRONOS-2 code for various fuel loadings in two to eight groups diffusion. Those core calculation have been validated against reference Monte-Carlo calculations and against core calculations with albedos boundary conditions. In addition to the increased easiness of utilization, the implemented equivalence method has yielded an improvement of the results for the two groups calculation. With a higher energy groups number, the use of a unique equivalent reflector does not account correctly for the two dimensions effects; a modelling with different reflector meshes has improved the results. The modelling of the reflector by two dimensions albedos boundary conditions is the more suited for the representation of the boundary conditions and, therefore, should the two dimensions albedos calculation

  7. In situ high-pressure X-ray diffraction experiments and ab initio calculations of Co2P

    Institute of Scientific and Technical Information of China (English)

    Zhang Qian; Wu Xiang; Qin Shan

    2011-01-01

    In situ high-pressure experiments of Co2P are carried out by means of angle dispersive X-ray diffraction with diamond anvil cell technique. No phase transition is observed in the present pressure range up to 15 GPa at room temperature2 even at high temperature and 15 GPa. Results of compression for Co2P are well presented by the second-order Birch-Murnaghan equation of state with VO = 130.99(2) (A)3 (1 (A)=0.1 nm) and KO = 160(3) GPa. Axial compressibilities are described by compressional modulus of the axis: Ka = 123(2) GPa, Kb = 167(8) GPa and Kc = 220(7) GPa. Theoretical calculations further support the experimental results and indicate that C23-type Co2P is stable at high pressure compared with the C22-type phase.

  8. Calculation and Correlation of the Unsteady Flowfield in a High Pressure Turbine

    Science.gov (United States)

    Bakhle, Milind A.; Liu, Jong S.; Panovsky, Josef; Keith, Theo G., Jr.; Mehmed, Oral

    2002-01-01

    Forced vibrations in turbomachinery components can cause blades to crack or fail due to high-cycle fatigue. Such forced response problems will become more pronounced in newer engines with higher pressure ratios and smaller axial gap between blade rows. An accurate numerical prediction of the unsteady aerodynamics phenomena that cause resonant forced vibrations is increasingly important to designers. Validation of the computational fluid dynamics (CFD) codes used to model the unsteady aerodynamic excitations is necessary before these codes can be used with confidence. Recently published benchmark data, including unsteady pressures and vibratory strains, for a high-pressure turbine stage makes such code validation possible. In the present work, a three dimensional, unsteady, multi blade-row, Reynolds-Averaged Navier Stokes code is applied to a turbine stage that was recently tested in a short duration test facility. Two configurations with three operating conditions corresponding to modes 2, 3, and 4 crossings on the Campbell diagram are analyzed. Unsteady pressures on the rotor surface are compared with data.

  9. First-Principles Calculations for Elastic Properties of ZnS under Pressure

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiang-Rong; HU Cui-E; ZENG Zhao-Yi; CAI Ling-Cang

    2008-01-01

    @@ The pressure dependence of elastic properties of ZnS in zinc-blende (ZB) and wurtzite (WZ) structures are investigated by the generalized gradient approximation (GGA) within the plane-wave pseudopotential density functional theory (DFT).Our results are in good agreement with the available experimental data and other theoretical results.

  10. Burnup calculations of light water-cooled pressure tube blanket for a fusion-fission hybrid reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zu, Tiejun, E-mail: tiejun@mail.xjtu.edu.cn; Wu, Hongchun; Zheng, Youqi; Cao, Liangzhi

    2014-06-15

    Highlights: • Detailed burnup calculations are performed on pressurized water cooled blankets with pressure tube assemblies. • The blanket is fueled with simple fuel, namely spent nuclear fuel discharged from light water reactors or natural uranium oxide. • The refueling strategies are proposed, and the uranium resource utilization rate can reach 5–6%. - Abstract: A fusion-fission hybrid reactor (FFHR) with pressure tube blanket has recently been proposed based on an ITER-type tokamak fusion neutron source and the well-developed pressurized water cooling technologies. In this paper, detailed burnup calculations are carried out on an updated blanket. Two different blankets respectively fueled with the spent nuclear fuel (SNF) discharged from light water reactors (LWRs) or natural uranium oxide is investigated. In the first case, a three-batch out-to-in refueling strategy is designed. In the second case, some SNF assemblies are loaded into the blanket to help achieve tritium self-sufficiency. And a three-batch in-to-out refueling strategies is adopted to realize direct use of natural uranium oxide fuel in the blanket. The results show that only about 80 tonnes of SNF or natural uranium are needed every 1500 EFPD (Equivalent Full Power Day) with a 3000 MWth output and tritium self-sufficiency (TBR > 1.15), while the required maximum fusion powers are lower than 500 MW for both the two cases. Based on the proposed refueling strategies, the uranium utilization rate can reach about 4.0%.

  11. Primary pressure standard based on piston-cylinder assemblies. Calculation of effective cross sectional area based on rarefied gas dynamics

    Science.gov (United States)

    Sharipov, Felix; Yang, Yuanchao; Ricker, Jacob E.; Hendricks, Jay H.

    2016-10-01

    Currently, the piston-cylinder assembly known as PG39 is used as a primary pressure standard at the National Institute of Standards and Technology (NIST) in the range of 20 kPa to 1 MPa with a standard uncertainty of 3× {{10}-6} as evaluated in 2006. An approximate model of gas flow through the crevice between the piston and sleeve contributed significantly to this uncertainty. The aim of this work is to revise the previous effective cross sectional area of PG39 and its uncertainty by carrying out more exact calculations that consider the effects of rarefied gas flow. The effective cross sectional area is completely determined by the pressure distribution in the crevice. Once the pressure distribution is known, the elastic deformations of both piston and sleeve are calculated by finite element analysis. Then, the pressure distribution is recalculated iteratively for the new crevice dimension. As a result, a new value of the effective area is obtained with a relative difference of 3× {{10}-6} from the previous one. Moreover, this approach allows us to reduce significantly the standard uncertainty related to the gas flow model so that the total uncertainty is decreased by a factor of three.

  12. Ultrafast nanoelectronics: steering electrons in infrared near-fields (Presentation Recording)

    Science.gov (United States)

    Herink, Georg; Ropers, Claus

    2015-09-01

    Plasmonic nanostructures can break the diffraction limit and confine optical fields on the nanoscale. The coupling of intense femtosecond transients to the apex of metallic nanotips enables ultrafast electron point sources which find applications in ultrafast electron microscopy and time-resolved diffraction instruments. In this contribution, we demonstrate the impact of near-field localization onto strong-field photoemission and present the control of electron trajectories via the momentary electric near-field. The photoemission dynamics at single gold and tungsten nanotips are experimentally studied over a broad range of excitation frequencies, spanning from 1 - 400 Terahertz (THz). The transition from oscillatory electron acceleration to a field-driven interaction is presented as a result of intense, long-wavelength and localized excitation. The high field enhancement at lower frequencies is demonstrated to induce localized field emission from a nanotip with moderate incident fields as provided by table-top THz sources. Such THz-induced cold field emission can be used, e.g., for the temporal tracking of optically excited hot-electron dynamics in nanostructures. Moreover, the field-driven electron acceleration in the enhanced THz near-field is employed in a pump-probe scheme to temporally map the local THz-response of the nanostructure by projecting the momentary apex near-field onto the kinetic energy of femtosecond electron pulses. Besides the electrical characterization of nanostructures at THz-frequencies, the temporally and spatially confined interaction of free electrons with ultrashort near-fields is expected to enable a novel class of ultrafast vacuum micro- and nanoelectronic devices, and first applications are presented in this talk.

  13. The ultrasonic velocity profile measurement of flow structure in the near field of a square free jet

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Y.; Yamashita, S. [Department of Mechanical and Systems Engineering, Gifu University (Japan); Kondo, K. [Department of Mechanical Engineering, Suzuka National College of Technology Shiroko, Mie (Japan)

    2002-02-01

    Coherent structures in the near field of a three-dimensional jet have been investigated. Experiments were carried out for a free jet issuing from a square nozzle using a water channel. Instantaneous velocity profiles were obtained in the axial and radial directions by using an ultrasonic velocity profile (UVP) monitor. Axial variations of dominant time-scales of vortex structures were examined from one-dimensional wavelet spectra. Wavenumber-frequency spectra were calculated by two-dimensional Fourier transform along the axial direction in a mixing layer, and it was found that a convective velocity of flow structures was nearly constant independently of their scales in space and time. Coherent structures in the axial direction were investigated in terms of proper orthogonal decomposition (POD). Eigenfunctions are similar to a sinusoidal wave, and reconstructed velocity fields by the lower-order and higher-order POD modes demonstrate large-scale and smaller-scale coherent structures, respectively. (orig.)

  14. The ultrasonic velocity profile measurement of flow structure in the near field of a square free jet

    Science.gov (United States)

    Inoue, Y.; Yamashita, S.; Kondo, K.

    Coherent structures in the near field of a three-dimensional jet have been investigated. Experiments were carried out for a free jet issuing from a square nozzle using a water channel. Instantaneous velocity profiles were obtained in the axial and radial directions by using an ultrasonic velocity profile (UVP) monitor. Axial variations of dominant time-scales of vortex structures were examined from one-dimensional wavelet spectra. Wavenumber-frequency spectra were calculated by two-dimensional Fourier transform along the axial direction in a mixing layer, and it was found that a convective velocity of flow structures was nearly constant independently of their scales in space and time. Coherent structures in the axial direction were investigated in terms of proper orthogonal decomposition (POD). Eigenfunctions are similar to a sinusoidal wave, and reconstructed velocity fields by the lower-order and higher-order POD modes demonstrate large-scale and smaller-scale coherent structures, respectively.

  15. Study on calculation of rock pressure for ultra-shallow tunnel in poor surrounding rock and its tunneling procedure

    Institute of Scientific and Technical Information of China (English)

    Xiaojun Zhou; Jinghe Wang; Bentao Lin

    2014-01-01

    A computational method of rock pressure applied to an ultra-shallow tunnel is presented by key block theory, and its mathematical formula is proposed according to a mechanical tunnel model with super-shallow depth. Theoretical analysis shows that the tunnel is subject to asymmetric rock pressure due to oblique topography. The rock pressure applied to the tunnel crown and sidewall is closely related to the surrounding rock bulk density, tunnel size, depth and angle of oblique ground slope. The rock pressure applied to the tunnel crown is much greater than that to the sidewalls, and the load applied to the left side-wall is also greater than that to the right sidewall. Mean-while, the safety of the lining for an ultra-shallow tunnel in strata with inclined surface is affected by rock pressure and tunnel support parameters. Steel pipe grouting from ground surface is used to consolidate the unfavorable surrounding rock before tunnel excavation, and the reinforcing scope is proposed according to the analysis of the asymmetric load induced by tunnel excavation in weak rock with inclined ground surface. The tunneling procedure of bench cut method with pipe roof protection is still discussed and carried out in this paper according to the special geological condition. The method and tunneling procedure have been successfully utilized to design and drive a real expressway tunnel. The practice in building the super-shallow tunnel has proved the feasibility of the calculation method and tunneling procedure presented in this paper.

  16. Lattice Boltzmann equation calculation of internal, pressure-driven turbulent flow

    CERN Document Server

    Hammond, L A; Care, C M; Stevens, A

    2002-01-01

    We describe a mixing-length extension of the lattice Boltzmann approach to the simulation of an incompressible liquid in turbulent flow. The method uses a simple, adaptable, closure algorithm to bound the lattice Boltzmann fluid incorporating a law-of-the-wall. The test application, of an internal, pressure-driven and smooth duct flow, recovers correct velocity profiles for Reynolds number to 1.25 x 10 sup 5. In addition, the Reynolds number dependence of the friction factor in the smooth-wall branch of the Moody chart is correctly recovered. The method promises a straightforward extension to other curves of the Moody chart and to cylindrical pipe flow.

  17. An intercomparison of POLARIS measurement results from the DTU-ESA Facility and from the ESTEC Near-Field Range

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Breinbjerg, Olav

    This report documents an intercomparison of measurement results of the POLARIS antenna from measurement at the DTU-ESA Spherical Near-Field Antenna Test Facility in August 2011 and from measurement at the ESTEC Near-Field Range in the fall 2012. The comparison was carried out at the DTU-ESA Facil......This report documents an intercomparison of measurement results of the POLARIS antenna from measurement at the DTU-ESA Spherical Near-Field Antenna Test Facility in August 2011 and from measurement at the ESTEC Near-Field Range in the fall 2012. The comparison was carried out at the DTU...

  18. Design of a Class of Antennas Utilizing MEMS, EBG and Septum Polarizers including Near-field Coupling Analysis

    Science.gov (United States)

    Kim, Ilkyu

    Recent developments in mobile communications have led to an increased appearance of short-range communications and high data-rate signal transmission. New technologies provides the need for an accurate near-field coupling analysis and novel antenna designs. An ability to effectively estimate the coupling within the near-field region is required to realize short-range communications. Currently, two common techniques that are applicable to the near-field coupling problem are 1) integral form of coupling formula and 2) generalized Friis formula. These formulas are investigated with an emphasis on straightforward calculation and accuracy for various distances between the two antennas. The coupling formulas are computed for a variety of antennas, and several antenna configurations are evaluated through full-wave simulation and indoor measurement in order to validate these techniques. In addition, this research aims to design multi-functional and high performance antennas based on MEMS (Microelectromechanical Systems) switches, EBG (Electromagnetic Bandgap) structures, and septum polarizers. A MEMS switch is incorporated into a slot loaded patch antenna to attain frequency reconfigurability. The resonant frequency of the patch antenna can be shifted using the MEM switch, which is actuated by the integrated bias networks. Furthermore, a high gain base-station antenna utilizing beam-tilting is designed to maximize gain for tilted beam applications. To realize this base-station antenna, an array of four dipole-EBG elements is constructed to implement a fixed down-tilt main beam with application in base station arrays. An improvement of the operating range with the EBG-dipole array is evaluated using a simple linkbudget analysis. The septum polarizer has been widely used in circularly polarized antenna systems due to its simple and compact design and high quality of circularity. In this research, the sigmoid function is used to smoothen the edge in the septum design, which

  19. Thermal-hydraulic calculations for a fuel assembly in a European Pressurized Reactor using the RELAP5 code

    Directory of Open Access Journals (Sweden)

    Skrzypek Maciej

    2015-09-01

    Full Text Available The main object of interest was a typical fuel assembly, which constitutes a core of the nuclear reactor. The aim of the paper is to describe the phenomena and calculate thermal-hydraulic characteristic parameters in the fuel assembly for a European Pressurized Reactor (EPR. To perform thermal-hydraulic calculations, the RELAP5 code was used. This code allows to simulate steady and transient states for reactor applications. It is also an appropriate calculation tool in the event of a loss-of-coolant accident in light water reactors. The fuel assembly model with nodalization in the RELAP5 (Reactor Excursion and Leak Analysis Program code was presented. The calculations of two steady states for the fuel assembly were performed: the nominal steady-state conditions and the coolant flow rate decreased to 60% of the nominal EPR flow rate. The calculation for one transient state for a linearly decreasing flow rate of coolant was simulated until a new level was stabilized and SCRAM occurred. To check the correctness of the obtained results, the authors compared them against the reactor technical documentation available in the bibliography. The obtained results concerning steady states nearly match the design data. The hypothetical transient showed the importance of the need for correct cooling in the reactor during occurrences exceeding normal operation. The performed analysis indicated consequences of the coolant flow rate limitations during the reactor operation.

  20. Heating rate and spin flip lifetime due to near field noise in layered superconducting atom chips

    CERN Document Server

    Fermani, Rachele; Zhang, Bo; Lim, Michael J; Dumke, Rainer

    2009-01-01

    We theoretically investigate the heating rate and spin flip lifetimes due to near field noise for atoms trapped close to layered superconducting structures. In particular, we compare the case of a gold layer deposited above a superconductor with the case of a bare superconductor. We study a niobium-based and a YBCO-based chip. For both niobium and YBCO chips at a temperature of 4.2 K, we find that the deposition of the gold layer can have a significant impact on the heating rate and spin flip lifetime, as a result of the increase of the near field noise. At a chip temperature of 77 K, this effect is less pronounced for the YBCO chip.

  1. Strong Near-Field Enhancement of Radiative Heat Transfer between Metallic Surfaces

    Science.gov (United States)

    Kralik, Tomas; Hanzelka, Pavel; Zobac, Martin; Musilova, Vera; Fort, Tomas; Horak, Michal

    2012-11-01

    Near-field heat transfer across a gap between plane-parallel tungsten layers in vacuo was studied experimentally with the temperature of the cold sample near 5 K and the temperature of the hot sample in the range 10-40 K as a function of the gap size d. At gaps smaller than one-third of the peak wavelength λm given by Wien’s displacement law, the near-field effect was observed. In comparison with blackbody radiation, hundred times higher values of heat flux were achieved at d≈1μm. Heat flux normalized to the radiative power transferred between black surfaces showed scaling (λm/d)n, where n≈2.6. This Letter describes the results of experiment and a comparison with present theory over 4 orders of magnitude of heat flux.

  2. Novel microwave near-field sensors for material characterization, biology, and nanotechnology

    CERN Document Server

    Joffe, R; Shavit, R

    2015-01-01

    The wide range of interesting electromagnetic behavior of contemporary materials requires that experimentalists working in this field master many diverse measurement techniques and have a broad understanding of condensed matter physics and biophysics. Measurement of the electromagnetic response of materials at microwave frequencies is important for both fundamental and practical reasons. In this paper, we propose a novel near-field microwave sensor with application to material characterization, biology, and nanotechnology. The sensor is based on a subwavelength ferrite-disk resonator with magnetic-dipolar-mode (MDM) oscillations. Strong energy concentration and unique topological structures of the near fields originated from the MDM resonators allow effective measuring material parameters in microwaves, both for ordinary structures and objects with chiral properties.

  3. Dynamic near-field nanofocusing by V-shaped metal groove via a femtosecond laser excitation

    Science.gov (United States)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Ou, Yan; Yong, Jiale; Hou, Xun

    2016-03-01

    The ultrafast dynamics of plasmonic near-field nanofocusing by a V-shaped groove milled on Au film via a femtosecond laser excitation is theoretically studied based on finite element method. The spatiotemporal evolution of the focused e-fields around the V-groove geometry is obtained. It is revealed that the strong nanofocusing at the V-shaped groove occurs at the moderate electron temperature of 3000 K in the electron-phonon uncoupled state via a femtosecond laser pulse excitation. The phenomenon is explained as the electron thermal dynamics manipulation of plasmon resonances due to femtosecond laser fluence modifications. This study provides basic understanding of ultrafast dynamics of near-field nanofocusing in V-shaped geometry for wide applications in the fields such as super-resolution imaging, SERS, and photothermal therapy.

  4. Prediction and near-field observation of skull-guided acoustic waves

    CERN Document Server

    Estrada, Héctor; Razansky, Daniel

    2016-01-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field properties unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  5. Electrically tunable near-field radiative heat transfer via ferroelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yi; Boriskina, Svetlana V.; Chen, Gang, E-mail: gchen2@mit.edu [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-12-15

    We explore ways to actively control near-field radiative heat transfer between two surfaces that relies on electrical tuning of phonon modes of ferroelectric materials. Ferroelectrics are widely used for tunable electrical devices, such as capacitors and memory devices; however, their tunable properties have not yet been examined for heat transfer applications. We show via simulations that radiative heat transfer between two ferroelectric materials can be enhanced by over two orders of magnitude over the blackbody limit in the near field, and can be tuned as much as 16.5% by modulating the coupling between surface phonon polariton modes at the two surfaces via varying external electric fields. We then discuss how to maximize the modulation contrast for tunable thermal devices using the studied mechanism.

  6. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

    Science.gov (United States)

    Li, Peining; Lewin, Martin; Kretinin, Andrey V.; Caldwell, Joshua D.; Novoselov, Kostya S.; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-06-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications.

  7. Observation of nanostructure by scanning near-field optical microscope with small sphere probe

    Directory of Open Access Journals (Sweden)

    Yasushi Oshikane, Toshihiko Kataoka, Mitsuru Okuda, Seiji Hara, Haruyuki Inoue and Motohiro Nakano

    2007-01-01

    Full Text Available Step and terrace structure has been observed in an area of 1 μm×1 μm on the cleaved surface of KCl–KBr solid-solution single crystal by scanning near-field optical microscope (SNOM with a small sphere probe of 500 nm diameter. Lateral spatial resolution of the SNOM system was estimated to be 20 nm from the observation of step width and the scanning-step interval. Vertical spatial resolution was estimated to be 5–2 nm from the observation of step height and noise level of photomultiplier tube (PMT. With applying a dielectric dipole radiation model to the probe surface, the reason why such a high spatial resolution was obtained in spite of the 500 nm sphere probe, was understood as the effect of the near-field term appeared in the radiation field equations.

  8. Decision making based on optical excitation transfer via near-field interactions between quantum dots

    CERN Document Server

    Naruse, Makoto; Aono, Masashi; Ohtsu, Motoichi; Sonnefraud, Yannick; Drezet, Aurélien; Huant, Serge; Kim, Song-Ju

    2014-01-01

    Optical near-field interactions between nanostructured matter, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain.

  9. Polymer nanofibers prepared by low-voltage near-field electrospinning

    Institute of Scientific and Technical Information of China (English)

    Zheng Jie; Long Yun-Ze; Sun Bin; Zhang Zhi-Hua; Shao Feng; Zhang Hong-Di; Zhang Zhi-Ming; Huang Jia-Yin

    2012-01-01

    Electrospinning is a straightforward method to produce micro/nanoscale fibers from polymer solutions typically using an operating voltage of 10 kV-30 kV and spinning distance of 10 cm-20 cm.In this paper,polyvinyl pyrrolidone (PVP) non-woven nanofibers with diameters of 200 nm-900 nm were prepared by low-voltage near-field electrospinning with a working voltage of less than 2.8 kV and a spinning distance of less than 10 mm.Besides the uniform fibers,beaded-fibers were also fabricated and the formation mechanism was discussed.Particularly,a series of experiments were carried out to explore the influence of processing variables on the formation of near-field electrospun PVP nanofibers,including concentration,humidity,collecting position,and spinning distance.

  10. Far-field and near-field investigation of plasmonic-photonic hybrid laser mode

    CERN Document Server

    Zhang, Taiping; Callard, Ségolène; jamois, Cecile; Letartre, Xavier; Chevalier, Celine; Rojo-Romeo, Pedro; Devif, Brice; Viktorovitch, Pierre

    2014-01-01

    We report an approach to achieve this goal via build a plasmonic-dielectric photonic hybrid system. We induce a defect mode based photonic crystal (PC) cavity to work as a intermedium storage as well as a near-field light source to excite a plasmonic nanoantenna (NA). In this way, a plasmonic-photonic nano-laser source is created in present experiment. The coupling condition between the two elements is investigated in far-field and near-field level. We found that the NA reduces the Q-factor of the PC-cavity. Meanwhile, the NA concentrates and enhances the laser emission of the PC-cavity. This novel hybrid dielectric-plasmonic structure may open a new avenue in the generation of nano-light sources, which can be applied in areas such as optical information storage, non-linear optics, optical trapping and detection, integrated optics, etc.

  11. Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes

    Science.gov (United States)

    Mendes, Manuel J.; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2011-08-01

    This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles' physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaics.

  12. Near-field radiative heat transfer between metamaterials coated with silicon carbide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Soumyadipta, E-mail: soumya.005@gmail.com; Yang, Yue; Wang, Liping, E-mail: liping.wang@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States)

    2015-01-19

    In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC. By careful tuning of the optical properties of metamaterial, it is possible to excite electrical and magnetic resonances for the metamaterial and surface phonon polaritons for SiC at different spectral regions, resulting in the enhanced heat transfer. The effect of the SiC film thickness at different vacuum gaps is investigated. Results obtained from this study will be beneficial for application of thin film coatings for energy harvesting.

  13. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    Science.gov (United States)

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-01

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  14. Reduction of truncation errors in planar, cylindrical, and partial spherical near-field antenna measurements

    DEFF Research Database (Denmark)

    Cano-Fácila, Francisco José; Pivnenko, Sergey; Sierra-Castaner, Manuel

    2012-01-01

    A method to reduce truncation errors in near-field antenna measurements is presented. The method is based on the Gerchberg-Papoulis iterative algorithm used to extrapolate band-limited functions and it is able to extend the valid region of the calculatedfar-field pattern up to the whole forward...... hemisphere. The extension of the valid region is achieved by the iterative application of atransformation between two different domains. After each transformation, a filtering process that is based on known information at each domain is applied. The first domain is the spectral domain in which the plane wave......, cylindrical, and partial spherical near-field measurements are considered. Several simulation and measurement examples are presented to verify the effectiveness of the method....

  15. The Mathematical Basis of the Inverse Scattering Problem for Cracks from Near-Field Data

    Directory of Open Access Journals (Sweden)

    Yao Mao

    2015-01-01

    Full Text Available We consider the acoustic scattering problem from a crack which has Dirichlet boundary condition on one side and impedance boundary condition on the other side. The inverse scattering problem in this paper tries to determine the shape of the crack and the surface impedance coefficient from the near-field measurements of the scattered waves, while the source point is placed on a closed curve. We firstly establish a near-field operator and focus on the operator’s mathematical analysis. Secondly, we obtain a uniqueness theorem for the shape and surface impedance. Finally, by using the operator’s properties and modified linear sampling method, we reconstruct the shape and surface impedance.

  16. Energy modulation of nonrelativistic electrons in an optical near field on a metal microslit

    Science.gov (United States)

    Ishikawa, R.; Bae, J.; Mizuno, K.

    2001-04-01

    Energy modulation of nonrelativistic electrons with a laser beam using a metal microslit as an interaction circuit has been investigated. An optical near field is induced in the proximity of the microslit by illumination of the laser beam. The electrons passing close to the slit are accelerated or decelerated by an evanescent wave contained in the near field whose phase velocity is equal to the velocity of the electrons. The electron-evanescent wave interaction in the microslit has been analyzed theoretically and experimentally. The theory has predicted that electron energy can be modulated at optical frequencies. Experiments performed in the infrared region have verified theoretical predictions. The electron-energy changes of more than ±5 eV with a 10 kW CO2 laser pulse at the wavelength of 10.6 μm has been successfully observed for an electron beam with an energy of less than 80 keV.

  17. Near-field manipulation of spectroscopic selection rules on the nanoscale.

    Science.gov (United States)

    Jain, Prashant K; Ghosh, Debraj; Baer, Roi; Rabani, Eran; Alivisatos, A Paul

    2012-05-22

    In conventional spectroscopy, transitions between electronic levels are governed by the electric dipole selection rule because electric quadrupole, magnetic dipole, and coupled electric dipole-magnetic dipole transitions are forbidden in a far field. We demonstrated that by using nanostructured electromagnetic fields, the selection rules of absorption spectroscopy could be fundamentally manipulated. We also show that forbidden transitions between discrete quantum levels in a semiconductor nanorod structure are allowed within the near-field of a noble metal nanoparticle. Atomistic simulations analyzed by an effective mass model reveal the breakdown of the dipolar selection rules where quadrupole and octupole transitions are allowed. Our demonstration could be generalized to the use of nanostructured near-fields for enhancing light-matter interactions that are typically weak or forbidden.

  18. Near-field optical microscopy and spectroscopy of few-layer black phosphorous

    Science.gov (United States)

    Frenzel, A. J.; Tran, S.; Hinton, J. P.; Sternbach, A. J.; Yang, J.; Gillgren, N.; Lau, C. N.; Basov, D. N.

    Few-layer black phosphorous is a recent addition to the family of two-dimensional (2D) materials which exhibits strongly anisotropic transport and optical properties due to its puckered honeycomb structure. It was recently predicted that this intrinsic anisotropy should manifest in the plasmon dispersion. Additionally, tuning layer number and carrier density can control the dispersion of these collective modes. Scanning near-field optical microscopy (SNOM) has been demonstrated as a powerful method to probe electronic properties, including propagating collective modes, in layered 2D materials. We used SNOM to investigate anisotropic carrier response in few-layer black phosphorous encapsulated by hexagonal boron nitride. In addition to exploring gate-voltage tunability of the electronic response, we demonstrate effective modulation of the near-field signal by ultrafast photoexcitation.

  19. Direct Measurement of Evanescent Wave Interference with a Scanning Near-field Optical Microscope

    Institute of Scientific and Technical Information of China (English)

    HONG Tao; WANG Jia; XU Tie-Jun; SUN Li-Qun

    2004-01-01

    @@ Evanescent wave interference is studied theoretically and experimentally. The interference patterns were directly measured with a scanning near-field optical microscope. The acquired image of the interference pattern is clear and has better contrast than that previously acquired with a photon-scanning tunnelling microscope or lasertrapped particles. The spatial period of the interference fringes is 180nm, which agrees with the theoretical value.The results indicate that the probe of the scanning near-field optical microscope has a resolution beyond 100 nm.The relation between the evanescent field intensity and the distance is also measured. When the separation between the probe and the interface is up to 180nm, the intensity can decrease to 1/e of the maximum.

  20. Electromagnetically induced transparency and absorption in plasmonic metasurfaces based on near-field coupling

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Ming-li, E-mail: mlwan@pdsu.edu.cn [College of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467000 (China); He, Jin-na [College of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467000 (China); Song, Yue-li [College of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467000 (China); New PV-energy Engineering Research Center, Pingdingshan University, Pingdingshan 467000 (China); Zhou, Feng-qun [College of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467000 (China)

    2015-09-04

    We theoretically investigate optical properties of a plasmonic metasurface consisting of a dipolar wire as the bright antenna stacked above a quadrupolar wire as the dark antenna. It is demonstrated that by adjusting the lateral displacement between the two resonators, the spectral feature of the metasurface can be evolved from the plasmonic electromagnetically-induced transparency to electromagnetically-induced absorption. The extracted physical parameters based on the two-coupled-oscillator model reveal that the near-field coupling strength plays a key role for the transition behavior in the plasmonic metasurface. - Highlights: • We study spectral response of metamaterial in dependence on near-field coupling. • Coupled two-oscillator is adopted to explain the spectral behavior. • For weak coupling, metamaterials exhibit an EIA-like feature. • For strong coupling, metamaterials exhibit an EIT-like profile.

  1. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Roy Chowdhury, Dibakar, E-mail: dibakar.roychowdhury@anu.edu.au [Center for Sustainable Energy Systems, College of Engineering and Computer Science, Australian National University, Canberra 0200 (Australia); College of Engineering, Mahindra Ecole Centrale, Jeedimetla, Hyderabad, 500043 (India); Xu, Ningning; Zhang, Weili [School of Electrical Engineering and Computer Science, Oklahoma State University, Stillwater, Oklahoma 87074 (United States); Singh, Ranjan, E-mail: ranjans@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2015-07-14

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  2. Polarization Properties in Apertureless-Type Scanning Near-Field Optical Microscopy.

    Science.gov (United States)

    Ishibashi, Takayuki; Cai, Yongfu

    2015-12-01

    Polarization properties of apertureless-type scanning near-field optical microscopy (a-SNOM) were measured experimentally and were also analyzed using a finite-difference time-domain (FDTD) simulation. Our study reveals that the polarization properties in the a-SNOM are maintained and the a-SNOM works as a wave plate expressed by a Jones matrix. The measured signals obtained by the lock-in detection technique could be decomposed into signals scattered from near-field region and background signals reflected by tip and sample. Polarization images measured by a-SNOM with an angle resolution of 1° are shown. FDTD analysis also reveals the polarization properties of light in the area between a tip and a sample are p-polarization in most of cases. PMID:26415540

  3. Microwave and Millimeter Wave Near-Field Methods for Evaluation of Radome Composites

    Science.gov (United States)

    Ravuri, M.; Abou-Khousa, M.; Kharkovsky, S.; Zoughi, R.; Austin, R.

    2008-02-01

    Radomes are used to protect critical communications and radar hardware from exposure to adverse environmental conditions while providing the necessary aerodynamic characteristics for airborne systems. Near-field microwave and millimeter wave nondestructive evaluation methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as disbond, delamination, moisture and oil intrusion, impact damage, etc. This paper presents the results of a comprehensive experimental effort using near-field imaging techniques (producing images with high spatial resolutions) at several frequency bands in the microwave and millimeter wave regions as well as electromagnetic simulations for detecting and evaluating the presence of disbonds in such structures.

  4. Information Content of the Near-Field I: Two-Dimensional Samples

    Science.gov (United States)

    Frazin, Richard A.; Fischer, David G.; Carney, P. Scott

    2004-01-01

    Limits on the effective resolution of many optical near-field experiments are investigated. The results are applicable to variants of total-internal-reflection microscopy (TIRM), photon-scanning-tunneling microscopy (PSTM), and near-field-scanning-optical microscopy (NSOM) in which the sample is weakly scattering and the direction of illumination may be controlled. Analytical expressions for the variance of the estimate of the complex susceptibility of an unknown two-dimensional object as a function of spatial frequency are obtained for Gaussian and Poisson noise models, and a model-independent measure is examined. The results are used to explore the transition from near-zone to far-zone detection. It is demonstrated that the information content of the measurements made at a distance of even one wavelength away from the sample is already not much different from the information content of the far field. Copyright 2004 Optical Society of America

  5. Near-field imaging of interacting nano objects with metal and metamaterial superlenses

    International Nuclear Information System (INIS)

    Employing rigorous electromagnetic theory we investigate optical the near-field imaging of two interacting dipole-like objects with metal and slightly lossy metamaterial nanoslab superlenses. Our analysis indicates that the dipole emission is suppressed by near-field interactions when the objects are close to the lens or each other. This strongly influences the image quality, in particular with objects of small size and high polarizability. The interference from two nearby objects also affects the resolution and subwavelength definition can only be obtained for objects with dipole moments predominantly orthogonal to the slab. Such an optimal imaging condition is achieved with excitation by total internal reflection. With simulations we show that in these circumstances, subwavelength resolutions of about λ/5 for silver superlens and λ/10 for metamaterial slab are reached. (paper)

  6. Near-Field Radiative Heat Transfer between Metamaterials coated with Silicon Carbide Film

    CERN Document Server

    Basu, Soumyadipta; Wang, Liping

    2014-01-01

    In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC.By careful tuning of the optical properties of metamaterial it is possible to excite electrical and magnetic resonance for the metamaterial and surface phonon polaritons for SiC at different spectral regions, resulting in the enhanced heat transfer. The effect of the SiC film thickness at different vacuum gaps is investigated. Results obtained from this study will be beneficial for application of thin film coatings for energy harvesting.

  7. Near-field aperture-probe as a magnetic dipole source and optical magnetic field detector

    CERN Document Server

    Denkova, Denitza; Silhanek, Alejandro V; Van Dorpe, Pol; Moshchalkov, Victor V

    2014-01-01

    Scanning near-field field optical microscopy (SNOM) is a technique, which allows sub-wavelength optical imaging of photonic structures. While the electric field components of light can be routinely obtained, imaging of the magnetic components has only recently become of interest. This is so due to the development of artificial materials, which enhance and exploit the typically weak magnetic light-matter interactions to offer extraordinary optical properties. Consequently, both sources and detectors of the magnetic field of light are now required. In this paper, assisted by finite-difference time-domain simulations, we suggest that the circular aperture at the apex of a metal coated hollow-pyramid SNOM probe can be approximated by a lateral magnetic dipole source. This validates its use as a detector for the lateral magnetic near-field, as illustrated here for a plasmonic nanobar sample. Verification for a dielectric sample is currently in progress. We experimentally demonstrate the equivalence of the reciproc...

  8. Study on the Optically Transparent Near-Field and Far-Field RFID Reader Antenna

    Directory of Open Access Journals (Sweden)

    Yuan Yao

    2014-01-01

    Full Text Available A study on the optically transparent RFID reader antenna which can operate in both near-field and far-field is proposed in this paper. The antenna with a dimension of 45 mm × 45 mm is fabricated using Indium tin oxide film and can operate from 915 to 935 MHz covering the China UHF RFID band. The strong and uniform magnetic field is excited by magnetic dipole source. Both simulation and measurement results are shown to illustrate the performance of the proposed antenna. The measured reading distances are up to 40 mm and 100 mm for near-field and far-field applications, respectively.

  9. Statistical mechanics of light elements at high pressure. VI - Liquid-state calculations with Thomas-Fermi-Dirac theory

    Science.gov (United States)

    Macfarlane, J. J.

    1984-01-01

    A model free energy is developed for hydrogen-helium mixtures based on solid-state Thomas-Fermi-Dirac calculations at pressures relevant to the interiors of giant planets. Using a model potential similar to that for a two-component plasma, effective charges for the nuclei (which are in general smaller than the actual charges because of screening effects) are parameterized, being constrained by calculations at a number of densities, compositions, and lattice structures. These model potentials are then used to compute the equilibrium properties of H-He fluids using a charged hard-sphere model. The results find critical temperatures of about 0 K, 500 K, and 1500 K, for pressures of 10, 100, and 1000 Mbar, respectively. These phase separation temperatures are considerably lower (approximately 6,000-10,000 K) than those found from calculations using free electron perturbation theory, and suggest that H-He solutions should be stable against phase separation in the metallic zones of Jupiter and Saturn.

  10. Structure and elasticity of Cmcm CaIrO3 and their pressure dependences: Ab initio calculations

    Science.gov (United States)

    Tsuchiya, Taku; Tsuchiya, Jun

    2007-10-01

    Cmcm CaIrO3 is isostructural to the newly discovered high-pressure postperovskite polymorph of MgSiO3 . Due to the high transition pressure in MgSiO3 over 100GPa , low-pressure analoglike CaIrO3 is substantial to investigate physical properties of the postperovskite phase experimentally. Here we perform ab initio density functional calculations of structural and elastic properties of CaIrO3 phases and compare them with the results reported for MgSiO3 phases in detail. Local spin density approximation produces a Pauli-paramagnetic metallic ground state for Pbnm CaIrO3 , while a very weak but finite antiferromagnetic moment appears in Cmcm phase at 0GPa . We also find that each component of the normalized elastic stiffness constants of CaIrO3 is largely discrepant from that of MgSiO3 particularly in shear components, though CaIrO3 shows the compression behavior roughly similar to MgSiO3 . Those contrasts in shear constants cause the different shear wave anisotropy style. Results suggest that at least regarding shear wave polarization anisotropy, CaIrO3 is unlikely to be a good low-pressure analog of MgSiO3 , and care must be taken when one extrapolates the elastic property of Cmcm CaIrO3 to the MgSiO3 postperovskite.

  11. Characterization of anisotropic nano-particles by using depolarized dynamic light scattering in the near field

    OpenAIRE

    D. Brogioli; Salerno, D; Cassina, V.; Sacanna, S.; Philipse, A. P.; F. Croccolo; Mantegazza, F.

    2009-01-01

    Light scattering techniques are widely used in many fields of condensed and sof t matter physics. Usually these methods are based on the study of the scattered light in the far field. Recently, a new family of near field detection schemes has been developed, mainly for the study of small angle light scattering. These techniques are based on the detection of the light intensity near to the sample, where light scattered at different directions overlaps but can be distinguished by Fourier transf...

  12. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

    OpenAIRE

    Li, Peining; Lewin, Martin; Kretinin, Andrey V.; Caldwell, Joshua D.; Novoselov, Kostya S.; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-01-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength d...

  13. Near Field Radiation Patterns for an Ultra-Wide-Band Antenna

    OpenAIRE

    Blackledge, Jonathan; Babajanov, Bazar

    2013-01-01

    We present a three-dimensional time dependent model for simulating the electromagnetic radiation field patterns generated by Ultra-Wide- Band (UWB) antennas. UWB antennas are pulsed mode radiators used to communicate information at high bit rates over short distance. This affects the spatial characteristics of the field patterns assumed to be generated when a Continuous Wave (CW) model is used and this paper investigates the difference between the near field intensity patterns generated when ...

  14. Near-field investigation of a plasmonic-photonic hybrid nanolaser

    CERN Document Server

    Zhang, Taiping; Callard, Ségolène; jamois, Cecile; Letartre, Xavier; Chevalier, Celine; Rojo-Romeo, Pedro; Devif, Brice; Viktorovitch, Pierre

    2014-01-01

    We report an approach of realization and characterization of a novel plasmonic-photonic hybrid nanodevice. The device comprises a plasmonic nano-antenna (NA) and a defect mode based PC cavity, and were fabricated based on a multi-step electron-beam lithography. The laser emission of the devices was demonstrated and the coupling conditions between the NA and PC cavity were investigated in near-field level.

  15. Mechanical and hydrological characterization of the near-field surrounding excavations in a geologic salt formation

    Energy Technology Data Exchange (ETDEWEB)

    Howard, Clifford L. [Sandia National Laboratories, Albuquerque, NM (United States)

    2014-09-01

    The technical basis for salt disposal of nuclear waste resides in salt’s favorable physical, mechanical and hydrological characteristics. Undisturbed salt formations are impermeable. Upon mining, the salt formation experiences damage in the near-field rock proximal to the mined opening and salt permeability increases dramatically. The volume of rock that has been altered by such damage is called the disturbed rock zone (DRZ).

  16. Scanning near-field optical microscopy utilizing silicon nitride probe photoluminescence

    OpenAIRE

    Lulevich, V.; Ducker, W. A.

    2005-01-01

    We describe a simple method for performing high-resolution scanning near-field optical microscopy (SNOM). A commercial Si3N4 tip is illuminated by an intense light source, which causes the tip to emit redshifted (inelastically scattered) light. Part of the redshifted light passes through a sample, allowing transmission light microscopy. By simple modification of a commercial atomic force microscopes (AFM), we are able to image many different samples with high-resolution optical microscopy, ac...

  17. Transfer of arbitrary quantum emitter states to near-field photon superpositions in nanocavities

    OpenAIRE

    Thijssen, Arthur C. T.; Martin J. Cryan; Rarity, John G.; Oulton, Ruth

    2012-01-01

    We present a method to analyze the suitability of particular photonic cavity designs for information exchange between arbitrary superposition states of a quantum emitter and the near-field photonic cavity mode. As an illustrative example, we consider whether quantum dot emitters embedded in "L3" and "H1" photonic crystal cavities are able to transfer a spin superposition state to a confined photonic superposition state for use in quantum information transfer. Using an established dyadic Green...

  18. Near-field nonlinear optical spectroscopy of Langmuir-Blodgett films

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Geisler, T.

    1998-01-01

    . The spatial resolution of similar to 100 nm is achieved in near-field SH images that are not correlated with either the topographical or the FH images. It is directly demonstrated that SH generation is most concentrated inside submicrometer-sized (800-500 nm) crystallike domains, which are oriented...... differently but predominantly in the dipping direction and whose SH efficiency is maximum for pump wavelengths in the range of 770-800 nm. (C) 1998 Optical Society of America....

  19. Development of the near field geochemistry model; Desarrollo de un modelo geoquimico de campo proximo

    Energy Technology Data Exchange (ETDEWEB)

    Arcos, D.; Bruno, J.; Duro, L.; Grive, M.

    2000-07-01

    This report discusses in a quantitative manner the evolution of the near field geochemistry as a result of the interactions between two different introducing granitic groundwaters and the FEBEX bentonite as a buffer material. The two granitic groundwaters considered are: SR-5 water, sampled in a borehole at 500 m depth in Mina Ratones, and a mean composition of different granitic groundwaters from the iberian Massif. The steel canister has also been introduced by considering the iron corrosion in anoxic conditions. (Author)

  20. Atomic resolution imaging at 2.5 GHz using near-field microwave microscopy

    OpenAIRE

    Lee, Jonghee; Long, Christian J.; Yang, Haitao; Xiang, Xiao-Dong; Takeuchi, Ichiro

    2010-01-01

    Atomic resolution imaging is demonstrated using a hybrid scanning tunneling/near-field microwave microscope (microwave-STM). The microwave channels of the microscope correspond to the resonant frequency and quality factor of a coaxial microwave resonator, which is built in to the STM scan head and coupled to the probe tip. We find that when the tip-sample distance is within the tunneling regime, we obtain atomic resolution images using the microwave channels of the microwave-STM. We attribute...

  1. Anomalous near-field heat transfer between a cylinder and a perforated surface

    OpenAIRE

    Rodriguez, Alejandro W.; Reid, M. T. Homer; Varela, Jaime; Joannopoulos, John D.; Capasso, Federico; Johnson, Steven G.

    2012-01-01

    We predict that the radiative heat-transfer rate between a cylinder and a perforated surface depends non-monotonically on their separation. This anomalous behavior, which arises due to near-field effects, is explained using a heuristic model based on the interaction of a dipole with a plate. We show that nonmonotonicity depends not only on geometry and temperature but also on material dispersion - for micron and submicron objects, nonmonotonicity is present in polar dielectrics but absent in ...

  2. Thermodynamics and energy conversion of near-field thermal radiation: Maximum work and efficiency bounds

    Directory of Open Access Journals (Sweden)

    Latella Ivan

    2014-01-01

    Full Text Available We analyse the process of conversion of near-field thermal radiation into usable work by considering the radiation emitted between two planar sources supporting surface phonon-polaritons. The maximum work flux that can be extracted from the radiation is obtained taking into account that the spectral flux of modes is mainly dominated by these surface modes. The thermodynamic efficiencies are discussed and an upper bound for the first law efficiency is obtained for this process.

  3. Tracking Cancer Patients Medical History Using Wireless Emerging Technology : Near Field Communication

    Directory of Open Access Journals (Sweden)

    Shivang Bhagat

    2015-02-01

    Full Text Available The principal objective of this paper is to present an effective solution for storing and retrieving a cancer patient’s medical history in hospitals, clinics and wherever else need be. We have used latest technologies like Near Field Communication (NFC as a medium for communication, MySQL server for storing the database i.e. EHR (Electronic Health Record of patients and lastly an Android application which will provide the interface for the same.

  4. Concept study of radar sensors for near-field tsunami early warning

    OpenAIRE

    Börner, Thomas; Galletti, Michele; Marquart, Nicolas Pascal; Krieger, Gerhard

    2010-01-01

    Off-shore detection of tsunami waves is a critical component of an effective tsunami early warning system (TEWS). Even more critical is the off-shore detection of local tsunamis, namely tsunamis that strike coastal areas within minutes after generation. In this paper we propose new concepts for near-field tsunami early detection, based on innovative and up-to-date microwave remote sensing techniques. We particularly introduce the NESTRAD (NEar-Space Tsunami RADar) concept, which consists of a...

  5. Thermodynamics and energy conversion of near-field thermal radiation: maximum work and efficiency bounds

    OpenAIRE

    Latella Ivan; Pérez-Madrid Agustín; Rubi J. Miguel

    2015-01-01

    We analyse the process of conversion of near-field thermal radiation into usable work by considering the radiation emitted between two planar sources supporting surface phonon-polaritons. The maximum work flux that can be extracted from the radiation is obtained taking into account that the spectral flux of modes is mainly dominated by these surface modes. The thermodynamic efficiencies are discussed and an upper bound for the first law efficiency is obtained for this process.

  6. Near-field/far-field interface of a near-surface low level radioactive waste site

    OpenAIRE

    Beadle, Ian R.; S. Boult; Graham, J.; Hand, V. L.; Humphreys, Paul; Trivedi, D. P.; Warwick, P.

    2004-01-01

    Experimental and Modelling studies have been used to investigate the biogeochemical processes occurring at the interface zone between the near-field and far-field of the Drigg Low- Level radioactive Waste (LLW) trenches. These have led to a conceptual model of interface biogeochemistry, which has subsequently been modelled by the BNFL code known as the Generalised Repository Model (GRM). GRM simulations suggest that as organic rich leachate migrates into the far-field, iron III minerals such ...

  7. Micromechanical effective elastic moduli of continuous fiber-reinforced composites with near-field fiber interactions

    OpenAIRE

    Ju, J. W.; Yanase, K

    2011-01-01

    A higher-order micromechanical framework is presented to predict the overall elastic deformation behavior of continuous fiber-reinforced composites with high-volume fractions and random-fiber distributions. By taking advantage of the probabilistic pair-wise near-field interaction solution, the interacting eigenstrain is analytically derived. Subsequently, by making use of the Eshelby equivalence principle, the perturbed strain within a continuous circular fiber is accounted for. Further, base...

  8. Level-Set Shape Reconstruction of Binary Permittivity Distributions from Near-Field Focusing Capacitance Measurements

    OpenAIRE

    Taylor, S H; Garimella, S V

    2014-01-01

    A near-field focusing capacitance sensor consists of an array of long, coplanar electrodes offset by a small interface gap from an identical orthogonal array of electrodes. The sensor may be used to characterize permittivity inhomogeneities in thin dielectric layers. The sensor capacitance measurements represent a tessellated matrix of integral-averaged values describing void content in a series of zones corresponding to the electrode crossing points (junctions) of the sensor. The sensor does...

  9. Photon sorting in the near field using subwavelength cavity arrays in the near-infrared

    Energy Technology Data Exchange (ETDEWEB)

    Mandel, Isroel M., E-mail: imandel@gc.cuny.edu; Lansey, Eli [Department of Physics, Graduate Center and City College of the City University of New York, New York 10016 (United States); Gollub, Jonah N.; Sarantos, Chris H.; Akhmechet, Roman [Phoebus Optoelectronics, New York, New York 10013 (United States); Golovin, Andrii B.; Crouse, David T. [Department of Electrical Engineering, The City College of New York, New York, New York 10031 (United States)

    2013-12-16

    A frequency selective metasurface capable of sorting photons in the near-infrared spectral range is designed, fabricated, and characterized. The metasurface, a periodic array of dielectric cylindrical cavities in a gold film, localizes and transmits light of two spectral frequency bands into spatially separated cavities, resulting in near-field light splitting. The design and fabrication methodologies of the metasurface are discussed. The transmittance and photon sorting properties of the designed structure is simulated numerically and the measured transmission is presented.

  10. Cost-Effective, Cognitive Undersea Network for Timely and Reliable Near-Field Tsunami Warning

    Directory of Open Access Journals (Sweden)

    X. Xerandy

    2015-07-01

    Full Text Available The focus of this paper is on developing an early detection and warning system for near-field tsunami to mitigate its impact on communities at risk. This a challenging task, given the stringent reliability and timeliness requirements, the development of such an infrastructure entails. To address this challenge, we propose a hybrid infrastructure, which combines cheap but unreliable undersea sensors with expensive but highly reliable fiber optic, to meet the stringent constraints of this warning system. The derivation of a low-cost tsunami detection and warning infrastructure is cast as an optimization problem, and a heuristic approach is used to determine the minimum cost network configuration that meets the targeted reliability and timeliness requirements. To capture the intrinsic properties of the environment and model accurately the main characteristics of the sound wave propagation undersea, the proposed optimization framework incorporates the Bellhop propagation model and accounts for significant environment factors, including noise, varying undersea sound speed and sea floor profile. We apply our approach to a region which is prone to near-field tsunami threats to derive a cost-effective under sea infrastructure for detection and warning. For this case study, the results derived from the proposed framework show that a feasible infrastructure, which operates with a carrier frequency of 12-KHz, can be deployed in calm, moderate and severe environments and meet the stringent reliability and timeliness constraints, namely 20 minutes warning time and 99 % data communication reliability, required to mitigate the impact of a near-field tsunami. The proposed framework provides useful insights and guidelines toward the development of a realistic detection and warning system for near-field tsunami.

  11. Development of Near-Field Microwave Microscope with the Functionality of Scanning Tunneling Spectroscopy

    Science.gov (United States)

    Machida, Tadashi; Gaifullin, Marat B.; Ooi, Shuuich; Kato, Takuya; Sakata, Hideaki; Hirata, Kazuto

    2010-11-01

    We describe the details of an original near-field scanning microwave microscope, developed for simultaneous measurements of local density-of-states (LDOS) and local ohmic losses (LOL). Improving microwave detection systems, we have succeeded in distinguishing the LDOS and LOL even between two low resistance materials; gold and highly orientated pyrolitic graphite. The experimental data indicate that our microscope holds a capability to investigate both LDOS and LOL in nanoscale.

  12. Rupture Process of the April 18, 1906 California Earthquake from near-field Tsunami Waveform Inversion

    OpenAIRE

    Lorito, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Piatanesi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Lomax, A.; ALomax Scientific

    2007-01-01

    The April 18, 1906 M8 California earthquake generated a small local tsunami that was recorded in the near-field by the Presidio, San Francisco tide-gage, located near the Golden Gate. We investigate the causative, tsunamigenic seismic source by forward modeling and nonlinear inversion of the Presidio marigram. We use existing seismological and geological observations to fix the fault system geometry and the surface slip on the onland portions of the San Andreas fault (SAF). We perform synthe...

  13. Near-field aperture-probe as a magnetic dipole source and optical magnetic field detector

    OpenAIRE

    Denkova, Denitza; Verellen, Niels; Silhanek, Alejandro V.; Van Dorpe, Pol; Moshchalkov, Victor V.

    2014-01-01

    Scanning near-field field optical microscopy (SNOM) is a technique, which allows sub-wavelength optical imaging of photonic structures. While the electric field components of light can be routinely obtained, imaging of the magnetic components has only recently become of interest. This is so due to the development of artificial materials, which enhance and exploit the typically weak magnetic light-matter interactions to offer extraordinary optical properties. Consequently, both sources and det...

  14. HEXANN-EVALU - a Monte Carlo program system for pressure vessel neutron irradiation calculation

    International Nuclear Information System (INIS)

    The Monte Carlo program HEXANN and the evaluation program EVALU are intended to calculate Monte Carlo estimates of reaction rates and currents in segments of concentric angular regions around a hexagonal reactor-core region. The report describes the theoretical basis, structure and activity of the programs. Input data preparation guides and a sample problem are also included. Theoretical considerations as well as numerical experimental results suggest the user a nearly optimum way of making use of the Monte Carlo efficiency increasing options included in the program

  15. High-pressure-high-temperature phase relations of MgGeO3 : First-principles calculations

    Science.gov (United States)

    Tsuchiya, Taku; Tsuchiya, Jun

    2007-09-01

    The high-pressure-high-temperature behavior of MgGeO3 has been investigated by first-principles computations. It is found that at 300K , the first transformation from ilmenite to orthorhombic perovskite at 24-38GPa is followed by the second one to the CaIrO3 structure at 51-56GPa . Quasiharmonic free energy calculations suggest that the first transformation has a negative Clapeyron slope ( -9.3MPa/K at 1000K ), whereas the second one has a less temperature-sensitive positive Clapeyron slope ( +7.8MPa/K at 1000K ). It is also confirmed that the LiNbO3 structure does not have its own stability P,T conditions. Pressure dependence of the Goldschmidt tolerance factor indicates a clear correlation between distortion of the perovskite structure and relative stability of perovskite and postperovskite structures.

  16. Design and methodology for calculating the environmental pressure index as a tool for environmental land planning: the case of Cundinamarca

    International Nuclear Information System (INIS)

    The aim of this work is to provide a practical tool to carry out environmental planning and management processes regarding the use of space, in a complex way including not only biophysical but socioeconomic criteria. In the context of river basin management the Environmental Social Pressure Index was created. This paper presents an Environmental Planning and Management definition, based on the Ecological Supporting Structure, as well as one of sustainability, worked out of several authors. This work offers the methodological sequence to design and calculate a customized Environmental Social Pressure Index according to the specific features of any given territory, using the conceptual framework developed earlier and the multivariate analysis and power laws tools. Finally we present an exercise to illustrate this process, developed for Cundinamarca for 1995

  17. Plant Explosion--Calculation of Pressure Relief%厂房的防爆--泄压面积计算

    Institute of Scientific and Technical Information of China (English)

    陆莺

    2014-01-01

    This paper analyzed the overal layout of explosi-on-proof plant and requirements needing at ention of monomer design, and discussed factors should be considered in the des-ign of pressure relief facilities that should be set in A or B class plant with explosion risk. In this paper, by the actual case, the author chose the vent to calculate the pressure relief area.%本文针对防爆厂房的整体布局及单体设计时需注意的要求进行了分析,对有爆炸危险的甲、乙类厂房应设置泄压设施在设计时应考虑的主要因素进行了阐述。本文以实际案例,选择泄爆口来计算泄压面积。

  18. Light transport in dense composite media: role of near-field coupling

    Science.gov (United States)

    Rezvani Naraghi, Roxana; Sukhov, Sergey; Sáenz, Juan José; Dogariu, Aristide

    In scattering media, optical waves comprise both homogeneous and evanescent components. At very high concentrations of scatterers, particles are located in close proximity and interact through evanescent near fields. Thus, in this regime the energy is not only carried by propagating waves but it also evolves through evanescent coupling between individual scatterers. We have shown that in dense composite media additional transmission channels open because of these near-field interactions between close proximity scatters and, consequently, a new regime of transport emerges. This is clearly beyond simple descriptions of scatterers acting independently of their environment and framed in terms of far-field characteristics such as Mie cross-sections. We will show that, because in the dense media the energy can transfer through both diffusion and evanescent channels, the total transmittance is T =TCS +TNF = 1 1 L (lCS* +lNF*) L (lCS* +lNF*) . Correcting the total transmission in this manner is appealing because it is done in terms of physically meaningful and measurable quantities such a near-field (NF) scattering cross-section σNF.

  19. Integrating electron and near-field optics: dual vision for the nanoworld

    Science.gov (United States)

    Haegel, Nancy M.

    2014-04-01

    The integration of near-field scanning optical microscopy (NSOM) with the imaging and localized excitation capabilities of electrons in a scanning electron microscope (SEM) offers new capabilities for the observation of highly resolved transport phenomena in the areas of electronic and optical materials characterization, semiconductor nanodevices, plasmonics and integrated nanophotonics. While combined capabilities for atomic force microscopy (AFM) and SEM are of obvious interest to provide localized surface topography in concert with the ease and large spatial dynamic range of SEM and dual beam imaging (e.g., in-situ AFM following focused ion beam modification), integration with near-field optical imaging capability can also provide access to localized transport phenomena beyond the reach of far-field systems. In particular, the flexibility that is achieved with the capability for independent, high resolution placement of an electron source, providing localized excitation in the form of free carriers, photons or plasmons, with scanning of the optical collecting tip allows for unique types of "dual-probe" experiments that directly image energy transfer. We review integrated near-field and electron optics systems to date, highlight applications in a variety of fields and suggest future directions.

  20. Near-field testing of the 15-meter model of the hoop column antenna

    Science.gov (United States)

    Hoover, J.; Kefauver, N.; Cencich, T.; Osborn, J.; Osmanski, J.

    1986-03-01

    The technical results from near-field testing of the 15-meter model of the hoop column antenna at the Martin Marietta Denver Aerospace facility are documented. The antenna consists of a deployable central column and a 15 meter hoop, stiffened by cables into a structure with a high tolerance repeatable surface and offset feed location. The surface has been configured to have four offset parabolic apertures, each about 6 meters in diameter, and is made of gold plated molybdenum wire mesh. Pattern measurements were made with feed systems radiating at frequencies of 7.73, 11.60, 2.27, 2.225, and 4.26 (all in GHz). This report (Volume 1) covers the testing from an overall viewpoint and contains information of generalized interest for testing large antennas. This volume discusses the deployment of the antenna in the Martin Facility and the measurements to determine mechanical stability and trueness of the reflector surface, gives the test program outline, and gives a synopsis of antenna electromagnetic performance. Three techniques for measuring surface mechanical tolerances were used (theodolites, metric cameras, and near-field phase), but only the near-field phase approach is included. The report also includes an error analysis. A detailed listing of the antenna patterns are provided for the 2.225 Ghz feed in Volume 3 of this report, and for all other feeds in Volume 2.

  1. Surface plasmon near-field resonance characteristics of silver shell nanocylinders arranged in triangular geometry.

    Science.gov (United States)

    Jacob, Jesly; R, Ajith; Mathew, Vincent

    2011-11-20

    The optical near-field surface plasmon effects of a triangular system of silver nanoshell cylinders are numerically studied using the two-dimensional finite difference time domain method. The dependence of interparticle distance, shell thickness of the cylinder, dielectric constant of shell core as well as embedding medium, and orientation of the optical source plane on the plasmonic resonances of the nanocylinder shells is studied. The plasmonic resonances are found to have strong dependence on the interparticle distance. As the size of the particle is increased, the field intensity peak shows a redshift. The resonance condition varies with the dielectric constant of the environment as well as the core. In addition, the orientation of the incident source plane has a significant role in the near-field intensity distribution. Since the near-field intensity has the same trend as that of the scattering cross section, the results can be used in the design of various applications like sensing, antennas, and waveguides. PMID:22108888

  2. Vortex rings and jets recent developments in near-field dynamics

    CERN Document Server

    Yu, Simon

    2015-01-01

    In this book, recent developments in our understanding of fundamental vortex ring and jet dynamics will be discussed, with a view to shed light upon their near-field behaviour which underpins much of their far-field characteristics. The chapters provide up-to-date research findings by their respective experts and seek to link near-field flow physics of vortex ring and jet flows with end-applications in mind. Over the past decade, our knowledge on vortex ring and jet flows has grown by leaps and bounds, thanks to increasing use of high-fidelity, high-accuracy experimental techniques and numerical simulations. As such, we now have a much better appreciation and understanding on the initiation and near-field developments of vortex ring and jet flows under many varied initial and boundary conditions. Chapter 1 outlines the vortex ring pinch-off phenomenon and how it relates to the initial stages of jet formations and subsequent jet behaviour, while Chapter 2 takes a closer look at the behaviour resulting from vor...

  3. Near-field focus steering along arbitrary trajectory via multi-lined distributed nanoslits.

    Science.gov (United States)

    Lee, Gun-Yeal; Lee, Seung-Yeol; Yun, Hansik; Park, Hyeonsoo; Kim, Joonsoo; Lee, Kyookeun; Lee, Byoungho

    2016-01-01

    The modulation of near-field signals has recently attracted considerable interest because of demands for the development of nano-scale optical devices that are capable of overcoming the diffraction limit of light. In this paper, we propose a new type of tuneable plasmonic lens that permits the foci of surface plasmon polariton (SPP) signals to be continuously steered by adjusting the input polarization state. The proposed structure consists of multi-lined nanoslit arrays, in which each array is tilted at a different angle to provide polarization sensitivity and the nanoslit size is adjusted to balance the relative amplitudes of the excited SPPs from each line. The nanoslits of each line are designed to focus SPPs at different positions; hence, the SPP focal length can be tuned by modifying the incident polarization state. Unlike in previously reported studies, our method enables plasmonic foci to be continuously varied with a smooth change in the incident linear polarization state. The proposed structures provide a novel degree of freedom in the multiplexing of near fields. Such characteristics are expected to enable the realization of active SPP modulation that can be applied in near-field imaging, optical tweezing systems, and integrated nano-devices. PMID:27620281

  4. High-fidelity spatial addressing of 43Ca+ qubits using near-field microwave control

    Science.gov (United States)

    Prado Lopes Aude Craik, Diana; Linke, Norbert; Allcock, David; Sepiol, Martin; Harty, Thomas; Ballance, Christopher; Stacey, Derek; Steane, Andrew; Lucas, David

    2016-05-01

    Individual addressing of qubits is essential for scalable quantum computation. Spatial addressing allows unlimited numbers of qubits to share the same frequency, whilst enabling arbitrary parallel operations. We present the latest experimental results obtained using a two-zone microfabricated surface trap designed to perform spatial, near-field microwave addressing of long-lived 43Ca+ ``atomic clock'' qubits held in separate trap zones (each of which feature four integrated microwave electrodes). Microwave near fields generated by multi-electrode chip ion traps are often difficult to faithfully simulate and a simple method of characterizing and testing trap chips before placement under ultra-high vacuum would significantly speed up trap design optimization. We describe a printed circuit board antenna for use in mapping microwave near-fields generated by ion-trap electrodes. The antenna is designed to measure fields down to 100 μ m away from trap electrodes and to be impedance matched at a desired spot frequency for an improved signal to noise ratio in field measurements. This work is supported by the US Army Research Office, EPSRC (UK) and the UK National Quantum Technologies Programme.

  5. FGG-NUFFT-Based Method for Near-Field 3-D Imaging Using Millimeter Waves

    Directory of Open Access Journals (Sweden)

    Yingzhi Kan

    2016-09-01

    Full Text Available In this paper, to deal with the concealed target detection problem, an accurate and efficient algorithm for near-field millimeter wave three-dimensional (3-D imaging is proposed that uses a two-dimensional (2-D plane antenna array. First, a two-dimensional fast Fourier transform (FFT is performed on the scattered data along the antenna array plane. Then, a phase shift is performed to compensate for the spherical wave effect. Finally, fast Gaussian gridding based nonuniform FFT (FGG-NUFFT combined with 2-D inverse FFT (IFFT is performed on the nonuniform 3-D spatial spectrum in the frequency wavenumber domain to achieve 3-D imaging. The conventional method for near-field 3-D imaging uses Stolt interpolation to obtain uniform spatial spectrum samples and performs 3-D IFFT to reconstruct a 3-D image. Compared with the conventional method, our FGG-NUFFT based method is comparable in both efficiency and accuracy in the full sampled case and can obtain more accurate images with less clutter and fewer noisy artifacts in the down-sampled case, which are good properties for practical applications. Both simulation and experimental results demonstrate that the FGG-NUFFT-based near-field 3-D imaging algorithm can have better imaging performance than the conventional method for down-sampled measurements.

  6. Near-field radiation between graphene-covered carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Richard Z.; Liu, Xianglei; Zhang, Zhuomin M., E-mail: zhuomin.zhang@me.gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2015-05-15

    It has been shown that at small separation distances, thermal radiation between hyperbolic metamaterials is enhanced over blackbodies. This theoretical study considers near-field radiation when graphene is covered on the surfaces of two semi-infinite vertically aligned carbon nanotube (VACNT) arrays separated by a sub-micron vacuum gap. Doped graphene is found to improve photon tunneling in a broad hyperbolic frequency range, due to the interaction with graphene-graphene surface plasmon polaritons (SPP). In order to elucidate the SPP resonance between graphene on hyperbolic substrates, vacuum-suspended graphene sheets separated by similar gap distances are compared. Increasing the Fermi energy through doping shifts the spectral heat flux peak toward higher frequencies. Although the presence of graphene on VACNT does not offer huge near-field heat flux enhancement over uncovered VACNT, this study identifies conditions (i.e., gap distance and doping level) that best utilize graphene to augment near-field radiation. Through the investigation of spatial Poynting vectors, heavily doped graphene is found to increase penetration depths in hyperbolic modes and the result is sensitive to the frequency regime. This study may have an impact on designing carbon-based vacuum thermophotovoltaics and thermal switches.

  7. Near-field radiation between graphene-covered carbon nanotube arrays

    Directory of Open Access Journals (Sweden)

    Richard Z. Zhang

    2015-05-01

    Full Text Available It has been shown that at small separation distances, thermal radiation between hyperbolic metamaterials is enhanced over blackbodies. This theoretical study considers near-field radiation when graphene is covered on the surfaces of two semi-infinite vertically aligned carbon nanotube (VACNT arrays separated by a sub-micron vacuum gap. Doped graphene is found to improve photon tunneling in a broad hyperbolic frequency range, due to the interaction with graphene-graphene surface plasmon polaritons (SPP. In order to elucidate the SPP resonance between graphene on hyperbolic substrates, vacuum-suspended graphene sheets separated by similar gap distances are compared. Increasing the Fermi energy through doping shifts the spectral heat flux peak toward higher frequencies. Although the presence of graphene on VACNT does not offer huge near-field heat flux enhancement over uncovered VACNT, this study identifies conditions (i.e., gap distance and doping level that best utilize graphene to augment near-field radiation. Through the investigation of spatial Poynting vectors, heavily doped graphene is found to increase penetration depths in hyperbolic modes and the result is sensitive to the frequency regime. This study may have an impact on designing carbon-based vacuum thermophotovoltaics and thermal switches.

  8. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials.

    Science.gov (United States)

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S; Zhang, Lin

    2016-10-14

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate.

  9. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials

    Science.gov (United States)

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S.; Zhang, Lin

    2016-10-01

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate.

  10. Degradation of silver near-field optical probes and its electrochemical reversal

    Science.gov (United States)

    Opilik, Lothar; Dogan, Üzeyir; Szczerbiński, Jacek; Zenobi, Renato

    2015-08-01

    Deterioration of the outstanding optical properties of elemental silver due to atmospheric corrosion compromises its use in the field of plasmonics. Therefore, more chemically inert, but more lossy, metals (e.g., gold) are often used as a compromise. Silver tips for near-field optical microscopy are only utilized by specialized laboratories with in-house tip production facilities. This article presents a time-dependent study of the effect of atmospheric corrosion on the electromagnetic enhancement of solid silver tips. It was found that chemical degradation renders them unusable for tip-enhanced Raman spectroscopy (TERS) within the first two days after production. Furthermore, we present a simple electrochemical method for recovering the enhancing effect of corroded silver tips, as well as for storing freshly prepared probes, for example, for easy shipment. The present work greatly simplifies the experimental aspects of near-field optical microscopy, which should make near-field optical techniques, and, in particular, TERS, more accessible to the scientific community.

  11. Near-field radiation between graphene-covered carbon nanotube arrays

    International Nuclear Information System (INIS)

    It has been shown that at small separation distances, thermal radiation between hyperbolic metamaterials is enhanced over blackbodies. This theoretical study considers near-field radiation when graphene is covered on the surfaces of two semi-infinite vertically aligned carbon nanotube (VACNT) arrays separated by a sub-micron vacuum gap. Doped graphene is found to improve photon tunneling in a broad hyperbolic frequency range, due to the interaction with graphene-graphene surface plasmon polaritons (SPP). In order to elucidate the SPP resonance between graphene on hyperbolic substrates, vacuum-suspended graphene sheets separated by similar gap distances are compared. Increasing the Fermi energy through doping shifts the spectral heat flux peak toward higher frequencies. Although the presence of graphene on VACNT does not offer huge near-field heat flux enhancement over uncovered VACNT, this study identifies conditions (i.e., gap distance and doping level) that best utilize graphene to augment near-field radiation. Through the investigation of spatial Poynting vectors, heavily doped graphene is found to increase penetration depths in hyperbolic modes and the result is sensitive to the frequency regime. This study may have an impact on designing carbon-based vacuum thermophotovoltaics and thermal switches

  12. Novel Scanning Near-Field Microwave Microscopes Capable of Imaging Semiconductors and Metals

    Science.gov (United States)

    Imtiaz, Atif; Tselev, Alexander; Anlage, Steven

    2003-03-01

    To study novel physics in condensed matter and materials science, experimental techniques of probing the high frequency electrical properties of materials are limited in resolution to the wavelength of the incident electromagnetic wave. We report here a novel near-field microscope that is capable of operation at radio and microwave frequencies[1]. The spatial resolution is comparable to NSOM in the scanning capacitance mode of the microscope[2]. Our objective is to image materials contrast at microwave frequencies and improve the spatial resolution. The microscope is sensitive to losses in materials, and we will present evidence of sheet resistance contrast in a Boron-doped Silicon sample. These experiments are performed with two versions of the near-field microwave microscope: one has integrated STM-feedback for distance control and the second one maintains a constant frequency shift through Distance Following technique. We will discuss the data on these films in light of a transmission line and lumped element model of the microscope. The microscope is an attractive platform for measuring local losses and local nonlinear properties of a rich variety of semiconducting and correlated-electron materials. [1] D.E. Steinhauer, et.al, "Quantitative Imaging of Sheet Resistance with a Scanning Near-Field Microwave Microscope", Appl. Phys. Lett. 72, 861 (1998) [2] Atif Imtiaz and Steven M. Anlage, "A novel STM-assisted microwave microscope with capacitance and loss imaging capability", Ultramicroscopy (in press); cond-mat/0203540

  13. A Novel Scanning Near-Field Microwave Microscope Capable of High Resolution Loss Imaging

    Science.gov (United States)

    Imtiaz, Atif

    2005-03-01

    To study novel physics in condensed matter and materials science, experimental techniques need to be pushed for better sensitivity and higher spatial resolution. Classical techniques of probing the high frequency electrical properties of materials are limited in resolution to the wavelength of the incident electromagnetic wave. We report here a novel near-field microwave microscope to image materials contrast, with 2.5 nm spatial resolution in capacitance. Our objective is to improve the spatial resolution in local loss imaging. We will present evidence of sheet resistance contrast in a Boron-doped Silicon sample on sub- micron length scales. We will present quantitative analysis of the data on the Boron-doped Silicon sample in light of evanescent wave model of the microscope that we have developed. In addition, the probe to sample interaction on nanometer length scales will be discussed [1]. This work has been supported by an NSF IMR Grant DMR-9802756, and the University of Maryland/Rutgers NSF-MRSEC through the Near Field Microwave Microscope Shared Experimental Facility Grant DMR-00-80008. [1] Atif Imtiaz, Marc Pollak, Steven M. Anlage, John D. Barry and John Melngailis, ``Near-Field Microwave Microscopy on nanometer length scales'', to be published in J. Appl. Phys. (Feb. 1, 2005).

  14. Fast IR imaging with sub-wavelength resolution using a transient near-field probe

    Energy Technology Data Exchange (ETDEWEB)

    Palanker, D.V.; Knippels, G.M.H.; Smith, T.I.; Alan Schwettman, H. [Picosecond FEL Center, W.W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States)

    1998-09-02

    We present a method for the remote generation of a transient near-field probe using conventional IR microscopy optics. Photo-induced reflectivity generated by picosecond pulses of visible light incident on the surface of a semiconductor substrate is used to create transient mirrors with dimensions determined by the spot size of the visible light. The IR light scattered by such sub-wavelength-size mirror is collected after propagating through the sample. As the sample is located on the semiconductor substrate, no near-field distance control is required, and the image can be taken at the speed of typical laser scanning microscope. And since the near-field probe is generated remotely - using light - the sample to be imaged can be covered by, or encased in, a transparent liquid or solid. The resolution of such an IR microscope is determined by the dimensions of the transient mirror, i.e., by the spot size of the visible light and its penetration depth into the substrate. To prevent resolution degradation due to diffusion of the photo-excited carriers in the substrate, the probe (IR) pulse duration should not exceed a few tens of picoseconds. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  15. Thermal management in MoS{sub 2} based integrated device using near-field radiation

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Jiebin [Department of Physics, National University of Singapore, Singapore 117546 (Singapore); Zhang, Gang, E-mail: zhangg@ihpc.a-star.edu.sg [Institute of High Performance Computing, A*STAR, Singapore 138632 (Singapore); Li, Baowen [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States)

    2015-09-28

    Recently, wafer-scale growth of monolayer MoS{sub 2} films with spatial homogeneity is realized on SiO{sub 2} substrate. Together with the latest reported high mobility, MoS{sub 2} based integrated electronic devices are expected to be fabricated in the near future. Owing to the low lattice thermal conductivity in monolayer MoS{sub 2}, and the increased transistor density accompanied with the increased power density, heat dissipation will become a crucial issue for these integrated devices. In this letter, using the formalism of fluctuation electrodynamics, we explored the near-field radiative heat transfer from a monolayer MoS{sub 2} to graphene. We demonstrate that in resonance, the maximum heat transfer via near-field radiation between MoS{sub 2} and graphene can be ten times higher than the in-plane lattice thermal conduction for MoS{sub 2} sheet. Therefore, an efficient thermal management strategy for MoS{sub 2} integrated device is proposed: Graphene sheet is brought into close proximity, 10–20 nm from MoS{sub 2} device; heat energy transfer from MoS{sub 2} to graphene via near-field radiation; this amount of heat energy then be conducted to contact due to ultra-high lattice thermal conductivity of graphene. Our work sheds light for developing cooling strategy for nano devices constructing with low thermal conductivity materials.

  16. NEAR-FIELD SOURCE LOCALIZATION METHOD AND APPLICATION USING THE TIME REVERSAL MIRROR TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Fu Yongqing; Jiang Yulei; Liu Zhanya

    2011-01-01

    In order to develop the acoustic keyboard for Personal Computer (PC),it is necessary to seek high-precision near-field source localization algorithm for identifying the keyboard characters.First of all,the focusing property of Time Reversal Mirror (TRM) is introduced,and then a mathematical model of microphone array receiving typing sound is established according to the realization of acoustic keyboard from which the TRM localization algorithm is carried out.The results through computer simulation show that the localization Root Mean Square Error (RMSE) performance of the algorithm can reach 10-3,which demonstrates that the algorithm possesses a high accuracy for the actual near-field acoustic source localization,with potential of developing the computer acoustic keyboard.Furthermore,for the purpose of testing its effect on actual near-field source localization,we organize three experiments for acoustic keyboard characters localization.The experiment results show that the positioning error of TRM algorithm is less than 1 cm within a provided acoustic keyboard region.This will provide theoretical guidance for the further research of computer acoustic keyboard.

  17. Comparison of void fraction profiles in subcooled boiling of low pressure by 3D measurement and MARS calculation

    International Nuclear Information System (INIS)

    The radial and axial characteristics of void fraction were measured in vertical concentric annulus for the subcooled boiling flow by two-conductivity probe. Experiments were carried at different levels of heat flux, mass flux, subcooling. The exit pressure of system is near the atmosphere. The range of average void fraction was up to 18% and that of the average liquid velocity were less than 0.85 m/sec. And area average void fractions measured at L/Dh=90.5, 80.1, 71.4 were compared with the calculation of MARS. Some subcooled boiling models were evaluated

  18. Calculation of the thermodynamic properties of a mixture of gases as a function of temperature and pressure

    Science.gov (United States)

    Colon, G.

    1981-01-01

    The evaluation of the thermodynamic properties of a gas mixture can be performed using a generalized correlation which makes use of the second virial coefficient. This coefficient is based on statistical mechanics and is a function of temperature and composition, but not of pressure. The method provides results accurate to within 3 percent for gases which are nonpolar or only slightly polar. When applied to highly polar gases, errors of 5 to 10 percent may result. For gases which associate, even larger errors are possible. The sequences of calculations can be routinely programmed for a digital computer. The thermodynamic properties of a mixture of neon, argon and ethane were calculated by such a program. The result will be used for the design of the gas replenishment system for the Energetic Gamma Ray Experiment Telescope.

  19. The Effects of Consistent Chemical Kinetics Calculations on the Pressure-Temperature Profiles and Emission Spectra of Hot Jupiters

    CERN Document Server

    Drummond, Benjamin; Baraffe, Isabelle; Amundsen, David S; Mayne, Nathan J; Venot, Olivia; Goyal, Jayesh

    2016-01-01

    In this work we investigate the impact of calculating non-equilibrium chemical abundances consistently with the temperature structure for the atmospheres of highly-irradiated, close-in gas giant exoplanets. Chemical kinetics models have been widely used in the literature to investigate the chemical compositions of hot Jupiter atmospheres which are expected to be driven away from chemical equilibrium via processes such as vertical mixing and photochemistry. All of these models have so far used pressure--temperature (P-T) profiles as fixed model input. This results in a decoupling of the chemistry from the radiative and thermal properties of the atmosphere, despite the fact that in nature they are intricately linked. We use a one-dimensional radiative-convective equilibrium model, ATMO, which includes a sophisticated chemistry scheme to calculate P-T profiles which are fully consistent with non-equilibrium chemical abundances, including vertical mixing and photochemistry. Our primary conclusion is that, in case...

  20. Offsite dose calculation manual guidance: Standard radiological effluent controls for pressurized water reactors

    International Nuclear Information System (INIS)

    This report contains guidance which may be voluntarily used by licensees who choose to implement the provision of Generic Letter 89-01, which allows Radiological Effect Technical Specifications (RETS) to be removed from the main body of the Technical Specifications and placed in the Offsite Dose Calculation Manual (ODCM). Guidance is provided for Standard Effluent Controls definitions, Controls for effluent monitoring instrumentation, Controls for effluent releases, Controls for radiological environmental monitoring, and the basis for Controls. Guidance on the formulation of RETS has been available in draft from (NUREG-0471 and -0473) for a number of years; the current effort simply recasts those RETS into Standard Radiological Effluent Controls for application to the ODCM. Also included for completeness are: (1) radiological environmental monitoring program guidance previously which had been available as a Branch Technical Position (Rev. 1, November 1979); (2) existing ODCM guidance; and (3) a reproduction of generic Letter 89-01