Efficient Calculation of Near Fields in the FDTD Method
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...
Project-90 Near-field calculations using CALIBRE
A comprehensive set of near-field calculations for the Swedish Nuclear Power Inspectorates Project-90 safety assessment has been performed using the CALIBRE model. In the majority of cases considered the redox front migrates through the bentonite buffer and into the rock, where it becomes effectively immobilised. The fracture remains in a reducing state, which means that for solubility-limited nuclides, the concentration at the bentonite/fracture interface can never be greater than the reducing solubility limit. The calculations also show that significant retardation occurs for nuclides which are even moderately sorbed. The effect is less pronounced in the wider fracture and high flow cases, as the opportunity for diffusion from the fracture to the rock matrix is reduced. In contrast, the release from the near-field of poorly-sorbed nuclides which are not solubility limited is governed by the release rate from the fuel, the diffusive mass transfer resistance of the buffer, rock matrix and fracture, the initial inventories and the nuclide half-lives. In the reference case, the maximum dose potential of nuclides emerging from the near-field occur for I-129 and was 3.2 x 10-7 Sv per canister-year, assuming the flux to be discharged directly into the wall receptor biosphere. The parameters which have the most impact on the reference base results are high flow, wide aperture and poor chemistry (i.e. high solubility limits and low sorption distribution coefficients). The effects of combining extreme values of parameters does not give results which are in proportion to their effect when applied in isolation. In the worst case variant (early canister failure high flow, wide aperture and poor chemistry) the maximum dose potential is 1.0 x 10-4 Sv per canister-year, compared with 8.9 x 10-6 Sv in the high flow case, 4.5 x 10-7 in the wide aperture case, 2.3 x 10-6 in the poor chemistry case and 3.9 x 10-6 in the early failure, wide aperture and high flow case. (au)
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.
Models for calculating radionuclide release from the near field
Radionuclides released from a damaged canister for spent fuel will leak out through a damage in the canister wall and spread through the surrounding backfill. They will further migrate into water bearing fractures in the rock, up through the backfill into the damaged zone around the drift and into the drift itself. Some substances may also diffuse through the rock to adjacent fracture zones. Underway the nuclides will sorb on the materials along the transport paths. This paper reports that this complex and variable transport geometry has been modelled using a technique where we use the advantage of the Integrated Finite Difference method combined with analytical solution at location where the numerical technique would need a very detailed discretization. Also, another model which is limited for transport calculations at steady state has been developed using the advantages of a network of transport resistance, coupled together in the same way as an electrical circuit network
Fast Near-Field Calculation for Volume Integral Equations for Layered Media
Kim, Oleksiy S.; Meincke, Peter; Breinbjerg, Olav
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...
Accurate near-field calculation in the rigorous coupled-wave analysis method
Weismann, Martin; Panoiu, Nicolae C
2015-01-01
The rigorous coupled-wave analysis (RCWA) is one of the most successful and widely used methods for modeling periodic optical structures. It yields fast convergence of the electromagnetic far-field and has been adapted to model various optical devices and wave configurations. In this article, we investigate the accuracy with which the electromagnetic near-field can be calculated by using RCWA and explain the observed slow convergence and numerical artifacts from which it suffers, namely unphysical oscillations at material boundaries due to the Gibb's phenomenon. In order to alleviate these shortcomings, we also introduce a mathematical formulation for accurate near-field calculation in RCWA, for one- and two-dimensional straight and slanted diffraction gratings. This accurate near-field computational approach is tested and evaluated for several representative test-structures and configurations in order to illustrate the advantages provided by the proposed modified formulation of the RCWA.
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....
Fast near-field calculation for volume integral equations for layered media
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 nea...
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).
Near-field acoustic holography with sound pressure and particle velocity measurements
Fernandez Grande, Efren
. 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......, and studied under the light of different measurement principles. A direct formulation in space domain has been proposed, and the experimental validity of the quantity has been demonstrated. Additionally, the use of rigid spherical microphone arrays in near-field acoustic holography has been examined...
Near-field ray calculation for multiple knife-edge diffraction
Whitteker, J. H.
1984-08-01
A new ray approximation for calculating the diffraction attenuation due to several knife edges takes into account the wave-normal direction of the diffracted wave in the near field, using the Fresnel approximation. The theory is intended for terrestrial radio wave propagation and for other situations where obstructions are nearly collinear. The far-field form of the wave is adopted, as in asymptotic theories, but the focal line of the diffracted ray pencil coincides with the diffracting edge only in the limit as the field point moves deep into the geometric shadow. In general, the ray passes above the diffracting edges rather than through them. The theory is developed for knife edges only, but may be adaptable to other shapes of diffracting obstruction. In the examples given, the calculated attenuations are much more accurate than if the far-field approximation is assumed, but less accurate than if the complete Fresnel integration is done. In a comparison with the complete Fresnel integration, the difference turns out to be less than 1 dB for five or fewer knife edges.
Direct calculation of energy streamlines in near-field thermal radiation
Accurate prediction of the energy propagation direction and the associated lateral shift is very important for the design of efficient energy conversion devices and sensors based on nanoscale thermal radiation. This paper concerns the direction of energy flow during near-field radiative transfer between two parallel plates separated by a vacuum gap. An improved formulation, fully consistent with fluctuational electrodynamics, is developed to correctly trace the energy streamlines inside the emitter, receiver, and the vacuum gap. The influence of surface waves on the direction of energy propagation as well as on the lateral shift of energy streamlines is elucidated. An important finding with the improved formulation is that the lateral shift in the emitter may exceed that in the vacuum gap. The method can be extended for tracing the energy streamlines in multilayered structures.
Direct analysis of dispersive wave fields from near-field pressure measurements
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
A new method to calculate near-field radiation excited by heterogeneous fault rupture
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.
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
Water vapor pressure calculation.
Hall, J R; Brouillard, R G
1985-06-01
Accurate calculation of water vapor pressure for systems saturated with water vapor can be performed using the Goff-Gratch equation. A form of the equation that can be adapted for computer programming and for use in electronic databases is provided. PMID:4008425
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)
Hydraulic calculation of pressure pipes
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.
Brogioli, Doriano
2008-01-01
Elastic light scattering has been extensively used to study samples showing a non uniform refraction index on lengthscales from a fraction of a micrometer to a fraction of a millimeter. Typically, a wide laser beam is sent through the sample, and the light scattered at any angle is measured by a detector in the far field. In this Ph. D. thesis, I describe three new techniques, which allow to measure the scattering intensities, working in the near field: hOmoyne Near Field Speckles (ONFS), hEterodyne Near Field Speckles (ENFS) and Schlieren-like Near Field Speckles (SNFS). Basically, the experimental setup consists in a wide laser beam passing through the sample; a lens forms an image of a plane at a given distance from the cell on a CCD sensor. The image, in the near field, shows speckles, since it is formed by the stochastical interference of the light coming from a random sample. I show that, under suitable conditions, the correlation function of such a field closely mirrors the correlation function of the ...
The calculation of pressure vessels
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)
ITER Port Interspace Pressure Calculations
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.
Near Field Communication Applications
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...
Gutierrez, Cristian E
2013-01-01
We present an abstract method in the setting of compact metric spaces which is applied to solve a number of problems in geometric optics. In particular, we solve the one source near field refraction problem. That is, we construct surfaces separating two homogenous media with different refractive indices that refract radiation emanating from the origin into a target domain contained in an n-1 dimensional hypersurface. The input and output energy are prescribed. This implies the existence of lenses focusing radiation in a prescribed manner.
Near field communications handbook
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
Near field heat transfer in superlattices
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.
Joseph, P.; Elliott, S. J.; Nelson, P. A.
1994-05-01
This paper examines the consequences of driving a single secondary loudspeaker to cancel the pressure due to some primary source at a point in its near field. This simple technique has been applied to the sound field in a highly reverberant room to produce zones of quiet in the vicinity of the loudspeaker, which have diameters that are typically equal to one-tenth of the acoustic wavelength, within which the sound pressure level is attenuated by at least 10 dB. The principal advantage gained with this strategy over other active techniques for controlling the sound field in rooms is that the sound pressure level well away from the control point is largely unaffected, an increase of only a small fraction of one dB being typical. Such a loudspeaker-microphone configuration could be located, for example, in the head rests of cars or aeroplanes, or indeed anywhere where the listener is seated for significant lengths of time and subjected to high ambient noise levels such that auditory comfort may be disturbed.
Thermal infrared near-field spectroscopy.
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
A comparison of inverse boundary element method and near-field acoustical holography
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...
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
Terahertz near-field microspectroscopy
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
TBM pressure models: calculation tools
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...
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 container
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
Heterodyne Near-Field Scattering
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.
Enthalpy Calculation for Pressurized Oxy- coal Combustion
Weihong Wu
2012-08-01
Full Text Available Oxy-fuel combustion is recognizing one of the most promising available technologies that zero emission accomplishment may be in the offing. With coal burned under the pressure of 6MPa and oxygen-enriched conditions, the high temperature and high pressure gaseous combustion product is composed of 95% CO2 and water-vapor, with the rest of O2, N2 and so on. However, once lauded as classic approach of resolving fuel gas enthalpy calculation pertaining to ideal gas at atmospheric pressure was restrained by pressure limitations. In this paper, the flue gas was assumed by an ideal mixture of four real gases system, and the equations for calculating the flue gas enthalpy were derived by using the cofunction method incorporating with the Dalton’s law of pressure summation based on the Virial equation. Consequently, the results showed that the calculation method on the basis of the Dalton’s law of pressure summation appears to be a reasonable enthalpy values for the 6MPa oxygen-enriched coal combustion as opposed to the inferior cofunction method.
Enthalpy Calculation for Pressurized Oxy- coal Combustion
Weihong Wu; Jingli Huang
2012-01-01
Oxy-fuel combustion is recognizing one of the most promising available technologies that zero emission accomplishment may be in the offing. With coal burned under the pressure of 6MPa and oxygen-enriched conditions, the high temperature and high pressure gaseous combustion product is composed of 95% CO2 and water-vapor, with the rest of O2, N2 and so on. However, once lauded as classic approach of resolving fuel gas enthalpy calculation pertaining to ideal gas at atmospheric pressure was rest...
Some applications of pressure distribution calculation
Pressure distribution calculations are used to evaluate the increase in pressure caused by synchrotron orbit radiation from the Trinstan accelerating ring. A study is also made to evaluate the local gas emission and leak from the accelerating and main rings. To determine the pressure distribution in a circular accelerator, an equation is generally derived by combining the mass conservation law and a law concerning the conductance for a given gas emission rate and evacuation rate of the vacuum pump, and it is solved under appropriate periodic boundary conditions. In the present study, the pressure distribution is calculated from a function based on the evacuation rate of the pump and the conductance of the conduit. The function, β (R) (where R is the 'resistance [s/l]' of the conduit, and used as the position coordinates), has the dimension of s/l, and its inverse represents the local evacuation rate. With this method, a reasonable value of about 1x10-5 molecules/photon is obtained for the gas emission rate at the arc portion. Reasonable results are also obtained for the change in average pressure and change in pressure distribution due to leak. It is demonstrated that the amount of leak can be easily determined by this method. (N.K.)
Pressure Calculations in Nanochannel Gas Flows
In this research, pressure driven flow within a nanochannel is studied for argon in rarefied gas states. A Molecular Dynamics simulation is used to resolve the density and stress variations. Normal stress calculations are based on Irving-Kirkwood method, which divides the stress tensor into its kinetic and virial parts. The kinetic component recovers pressure based on the ideal-gas law. The particle-particle virial increases with increased density. The kinetic part and the virial part of the pressure is studied from Kn = 0.1 to Kn = 0.5 at 300 K. This pressure calculation was also compared with a simulation for a static fluid. Pressure driven gas flow gives a different result compared to static situation, which has a uniform particle distribution across the system. For a flow situation, the virial part is no longer the same. This can also be predicted from the virial equation and by the fact that the compressible fluid flow causes a temperature and density difference along the flow direction. The relation between the virial and distribution of particles has been studied further to understand the nature of virial component along the flow direction in compressible flows.
Pressure Correction in Density Functional Theory Calculations
Lee, S H
2008-01-01
First-principles calculations based on density functional theory have been widely used in studies of the structural, thermoelastic, rheological, and electronic properties of earth-forming materials. The exchange-correlation term, however, is implemented based on various approximations, and this is believed to be the main reason for discrepancies between experiments and theoretical predictions. In this work, by using periclase MgO as a prototype system we examine the discrepancies in pressure and Kohn-Sham energy that are due to the choice of the exchange-correlation functional. For instance, we choose local density approximation and generalized gradient approximation. We perform extensive first-principles calculations at various temperatures and volumes and find that the exchange-correlation-based discrepancies in Kohn-Sham energy and pressure should be independent of temperature. This implies that the physical quantities, such as the equation of states, heat capacity, and the Gr\\"{u}neisen parameter, estimat...
Near field optics and nanoscopy
Fillard, J P
1996-01-01
This book contains the most recent information on optical nanoscopy. Far-Field and Near-Field properties on e.m. waves are presented which illustrate how optical images can be obtained from sub-micron objects. Scanning Probe techniques and computer processing are covered here. An explanation is given on how propagating photons or evanescent waves can behave over distances shorter than the wavelength, taking into account the presence of small objects. Quantum tunneling of photons is explained comparatively with the electron mechanism. Technical details are given on photon tunneling microscopes.
Experimental determinations of the solubilities of americium, plutonium, neptunium, protactinium, thorium, radium, lead, tin, palladium and zirconium are reported. These elements have radioactive isotopes of concern in assessments of radioactive waste disposal. All measurements were made under the highly alkaline conditions typical of the near field of a radioactive waste repository which uses cementitious materials for many of the immobilisation matrices, the backfill and the engineered structures. Low redox potentials, typical of those resulting from the corrosion of iron and steel, were simulated for those elements having more than one accessible oxidation state. The dissolved concentrations of the elements were defined using ultrafiltration. In addition, the corrosion of iron and stainless steel was shown to generate low redox potentials in solution and the solubility of iron(II) at high pH was measured and found to be sufficient for it to act as a redox buffer with respect to neptunium and plutonium. (author)
Calculation of plantar pressure time integral, an alternative approach.
Melai, Tom; IJzerman, T Herman; Schaper, Nicolaas C; de Lange, Ton L H; Willems, Paul J B; Meijer, Kenneth; Lieverse, Aloysius G; Savelberg, Hans H C M
2011-07-01
In plantar pressure measurement, both peak pressure and pressure time integral are used as variables to assess plantar loading. However, pressure time integral shows a high concordance with peak pressure. Many researchers and clinicians use Novel software (Novel GmbH Inc., Munich, Germany) that calculates this variable as the summation of the products of peak pressure and duration per time sample, which is not a genuine integral of pressure over time. Therefore, an alternative calculation method was introduced. The aim of this study was to explore the relevance of this alternative method, in different populations. Plantar pressure variables were measured in 76 people with diabetic polyneuropathy, 33 diabetic controls without polyneuropathy and 19 healthy subjects. Peak pressure and pressure time integral were obtained using Novel software. The quotient of the genuine force time integral over contact area was obtained as the alternative pressure time integral calculation. This new alternative method correlated less with peak pressure than the pressure time integral as calculated by Novel. The two methods differed significantly and these differences varied between the foot sole areas and between groups. The largest differences were found under the metatarsal heads in the group with diabetic polyneuropathy. From a theoretical perspective, the alternative approach provides a more valid calculation of the pressure time integral. In addition, this study showed that the alternative calculation is of added value, along peak pressure calculation, to interpret adapted plantar pressures patterns in particular in patients at risk for foot ulceration. PMID:21737281
Near-field acoustical holography of military jet aircraft noise
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.
Sampling Criterion for EMC Near Field Measurements
Franek, Ondrej; Sørensen, Morten; Ebert, Hans; Pedersen, Gert Frølund
An alternative, quasi-empirical sampling criterion for EMC near field measurements intended for close coupling investigations is proposed. The criterion is based on maximum error caused by sub-optimal sampling of near fields in the vicinity of an elementary dipole, which is suggested as a worst...
Near Field Communication: Introduction and Implications
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,…
Dynamic calculations of pressurized water reactor internals
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.)
Spherical wave rotation in spherical near-field antenna measurements
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...
Infrared spectroscopic near-field mapping of single nanotransistors.
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
Infrared spectroscopic near-field mapping of single nanotransistors
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.
Evaluation of seismic stability of near field
For the buffer material of geological disposal of high-level radioactive waste (HLW) in Japan, it is considered to use a compacted bentonite or a compacted sand-mixture bentonite that is one kind of clay. The buffer material is expected to maintain long-term mechanical stability, to hold the waste in designated place, and to avoid the effects on the radionuclides migration. It is considered that the cyclic load due to seismic activities affects long-term mechanical stability in Japan, where many earthquakes have been occurring. In this report, aseismic mechanical stability of engineered barrier of HLW is studied by dynamic analysis based on equation of vibration, mainly in the view point of mechanical stability of the buffer. The analytical computer code that has been developed by JNC in cooperative project with National Research Institute for Earth Science and Disaster Prevention Science and Technology Agency is used in this study. Seismic wave at the disposal depth in the assumed geological environment is established by multiple reflection theory analysis, and then seismic wave at the disposal depth is used for the aseismic mechanical stability analysis. For the aseismic mechanical stability, total stress analyses (single-phase system) with the target field of near field are conducted to evaluate the shear failure of the buffer, the displacement of overpack, and vibrational behavior of the engineered barrier, and then effective stress analyses (two-phase system) with the target field of the engineered barrier are conducted to evaluate excursion in the pore water pressure within the buffer (i. e. liquefaction), concerning the non-linear dynamic properties of the buffer material. From the results, the following conclusions are obtained. (1) From the results of the total stress analyses, it is confirmed that the buffer must not reach a shear failure condition from the stresses caused by an earthquake and the overpack must not move significantly due to the inertial
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)
Development of a statistical procedure for rod internal pressure calculation
A statistical procedure which checks rod internal pressure criterion is developed. Variations in fuel fabrication and model parameters are considered statistically to obtain rod internal pressure. A sample calculation is presented using the numerical values for 17x17 rod array fuel assemblies. The results indicate that the statistical procedure predicts much smaller value of rod internal pressure(RIP) than the deterministic procedure which uses the worst combination of fuel fabrication and model parameters in the sense of rod internal pressure
Methodological problems in pressure profile calculations for lipid bilayers
Sonne, Jacob; Hansen, Flemming Yssing; Peters, Günther H.J.
2005-01-01
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......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...... and H profiles are calculated in order to test the uniqueness of the profile. The second problem is how to include electrostatic interactions in pressure profile calculations when the simulations are conducted without truncating the electrostatic potential, i.e., using the Ewald summation technique...
Measurements of near-field blast effects using kinetic plates
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.
Near-field characterization of plasmonic waveguides
Zenin, Volodymyr
2014-01-01
range simply by changing geometric parameters of the waveguide, keeping in mind the trade-off between confinement and propagation losses. A broad variety of plasmonic waveguides and waveguide components, including antennas for coupling the light in/out of the waveguide, requires correspondent...... characterization capabilities, especially on experimental side. The most straight-forward and powerful technique for such purpose is scanning near-field optical microscopy, which allows to probe and map near-field distribution and therefore becomes the main tool in this project. The detailed description of the...
Attosecond nanoscale near-field sampling
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.
Near-field/altered-zone models report
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
Near-field/altered-zone models report
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
Patch near field acoustic holography based on particle velocity measurements
Zhang, Yong-Bin; Jacobsen, Finn; Bi, Chuan-Xing; Chen, Xin-Zhao
2009-01-01
Patch near field acoustic holography (PNAH) based on sound pressure measurements makes it possible to reconstruct the source field near a source by measuring the sound pressure at positions on a surface. that is comparable in size to the source region of concern. Particle velocity is an alternative...... examines the use of particle velocity as the input of PNAH. Because the particle velocity decays faster toward the edges of the measurement aperture than the pressure does and because the wave number ratio that enters into the inverse propagator from pressure to velocity amplifies high spatial frequencies......, PNAH based on particle velocity measurements can give better results than the pressure-based PNAH with a reduced number of iterations. A simulation study, as well as an experiment carried out with a pressure-velocity sound intensity probe, demonstrates these findings....
Near-field compact dielectric optics
Feuermann, Daniel; Gordon, Jeffrey M.; Ng, Tuck Wah
2006-08-01
Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle.
Characterization of near-field optical probes
Vohnsen, Brian; Bozhevolnyi, Sergey I.
1999-01-01
Radiation and collection characteristics of four different near-field optical-fiber probes, namely, three uncoated probes and an aluminium-coated small-aperture probe, are investigated and compared. Their radiation properties are characterized by observation of light-induced topography changes in a...... characterization....
Antenna Near-Field Probe Station Scanner
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.
Computational lens for the near field
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...
Pore pressure calculation of the UO2 high burnup structure
Highlights: • Pore pressure is calculated based on local burnup, density and porosity. • Ronchi's equations of state are used instead of van der Waals’ equation. • Pore pressure increases as HBS transformation begins and then stays constant. • A best approximated parameter used for pore pressure calculation is recommended. -- Abstract: UO2 high burnup structure has an important impact on fuel behavior, especially in case of reactivity initiated accident (RIA). Pore relaxation enhances local fuel swelling and puts additional load to the fuel cladding, which makes fuel more susceptible to pellet–cladding mechanical interaction induced failure. Therefore, pore pressure calculation becomes vital when evaluating the fuel failure. In this paper pore pressure is calculated as a function of pellet radial local burnup based on the basic characteristics of HBS using Ronchi's correlation. The results indicate that pore pressure will approach a stable value as HBS is developing. A best approximated C value of 55 N/m is recommended for pore pressure calculation
Analytical stress tensor and pressure calculations with the CRYSTAL code
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 ...
Measurement of incident sound power using near field acoustic holography
Jacobsen, Finn; Tiana Roig, Elisabet
2009-01-01
The conventional method of measuring the insertion loss of a partition relies on an assumption of the sound field in the source room being diffuse and the classical relation between the spatial average of the mean square pressure in the source room and the incident sound power per unit area; and it...... has always been regarded as impossible to measure the sound power that is incident on a wall directly. This paper examines a new method of determining this quantity from sound pressure measurements at positions on the wall using ‘statistically optimised near field acoustic holography’ (SONAH). The...
Impeller response calculation due to complex pressure loading
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.
Near-field mapping by laser ablation of PMMA coatings
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...
Near-field effects of asteroid impacts in deep water
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.
A near-field optical microscopy nanoarray
Semin, D.J.; Ambrose, W.P.; Goodwin, P.M.; Kwller, A. [Los Alamos National Lab., NM (United States); Wendt, J.R. [Sandia National Labs., Albuquerque, NM (United States)
1996-12-31
Multiplexing near-field scanning optical microscopy (NSOM) by the use of a nanoarray with parallel imaging is studied. The fabrication, characterization, and utilization of nanoarrays with {approximately} 100 nm diameter apertures spaced 500 nm center-to- center is presented. Extremely uniform nanoarrays with {approximately} 10{sup 8} apertures were fabricated by electron beam lithography and reactive ion etching. The nanoarrays were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In this paper we utilize these nanoarrays in a laser-illuminated microscope with parallel detection on a charge- coupled device (CCD). Detection of B-phycoerythrin (B-PE) molecules using near-field illumination is presented. In principle, our system can be used to obtain high lateral resolution NSOM images over a wide-field of view (e.g. 50-100 {mu}m) within seconds.
Review of near-field optical microscopy
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.
Near-field thermal electromagnetic transport
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...
The geochemistry of the near-field
This report describes a study of the Swiss disposal concept used in 'Project Gewaehr 1985' safety analysis. The main components of the near-field of a high level waste repository are the waste glass matrix, the thick steel canister and the surrounding backfill of compressed bentonite. In this report it is concluded that mineralogical alteration of the backfill will be negligibly small over the million year period considered. Its physical and chemical properties can thus be relied on for such a period. The canister will retain its integrity for > 10/sup 3/ y and thereafter will act as an Eh/pH buffer. The near-field buffers ensure more alkaline and reducing conditions than in the far-field. Complete degradation of the glass matrix will take > 10/sup 5/ years and nuclide release will be limited by their congruent dissolution although it may be further constrained by low solubility. Diffusion of dissolved nuclides through the backfill is so slow that many species decay to insignificance within it. The large uptake capacity of the bentonite also significantly extends the release duration for longer lived, non-solubility limited nuclides thus decreasing output mixima. Possible perturbing factors such as radiolysis and hydrogen production by anoxic corrosion are of little importance but modelling of speciation/solubility in the near-field and, in particular, colloid formation and mobility are identified as areas in which more work is required. Although the main analysis aims to err on the side of conservatism, the extent of such pessimism is assessed in a 'realistic' appraisal of the near-field. This suggests that the engineered barriers will prevent any radiologically significant releases over periods in excess of a million years which would strengthen their role in the multiple barrier safety concept. (author)
Evaluation of near-field earthquake effects
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.
THz Near-Field Microscopy and Spectroscopy
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...
Near Field Communication: Technology and Market Trends
Gabriella Arcese; Giuseppe Campagna; Serena Flammini; Olimpia Martucci
2014-01-01
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 paymen...
Development of the near field geochemistry model
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)
On the pressure calculation for polarizable models in computer simulation.
Kiss, Péter T; Baranyai, András
2012-03-14
We present a short overview of pressure calculation in molecular dynamics or Monte Carlo simulations. The emphasis is given to polarizable models in order to resolve the controversy caused by the paper of M. J. Louwerse and E. J. Baerends [Chem. Phys. Lett. 421, 138 (2006)] about pressure calculation in systems with periodic boundaries. We systematically derive expressions for the pressure and show that despite the lack of explicit pairwise additivity, the pressure formula for polarizable models is identical with that of nonpolarizable ones. However, a strict condition for using this formula is that the induced dipole should be in perfect mechanical equilibrium prior to pressure calculation. The perfect convergence of induced dipoles ensures conservation of energy as well. We demonstrate using more cumbersome but exact methods that the derived expressions for the polarizable model of water provide correct numerical results. We also show that the inaccuracy caused by imperfect convergence of the induced dipoles correlates with the inaccuracy of the calculated pressure. PMID:22423830
Calculation of transitional boundary layer under pressure gradient
A modified κ-ε model is proposed for calculation of transitional boundary-layer flows under pressure gradient with high freestream turbulence intensity. In order to develop the model for this problem, the flow is divided into three regions; pre-transition region, transition region and fully turbulent region. The effect of pressure gradient is taken into account in a stream-wise intermittency factor, bridging the eddy-viscosities between in the pre-transition region and in the fully turbulent region. From intermittency data in various flows, Narashima's intermittency function, F(γ), has been found to be proportional to xn according to the extent of pressure gradient. Three empirical correlations of intermittency factor being analyzed, the best one was chosen to calculate three benchmark cases of bypass transition under pressure gradient. It was found that the variations of skin friction and shape factor as well as the profiles of mean velocity in the transition region were very satisfactorily predicted
Two benchmarks for qualification of pressure vessel fluence calculational methodology
Two benchmarks for the qualification of the pressure vessel fluence calculational methodology were formulated and are briefly described. The Pool Critical Assembly (PCA) benchmark is based on the experiments performed at the PCA in Oak Ridge. The measured quantities to be compared against the calculated values are the equivalent fission fluxes at several locations in front, behind, and inside the pressure-vessel wall simulator. This benchmark is particularly suitable to test the capabilities of the calculational methodology and cross-section libraries to predict in-vessel gradients because only a few approximations are necessary in the analysis. The HBR-2 benchmark is based on the data for the H.B. Robinson-2 plant, which is a 2,300 MW (thermal) pressurized light-water reactor. The benchmark provides the reactor geometry, the material compositions, the core power distributions, and the power historical data. The quantities to be calculated are the specific activities of the radiometric monitors that were irradiated in the surveillance capsule and in the cavity location during one fuel cycle. The HBR-2 benchmark requires modeling approximations, power-to-neutron source conversion, and treatment of time dependant variations. It can therefore be used to test the overall performance and adequacy of the calculational methodology for power-reactor pressure-vessel flux calculations. Both benchmarks were analyzed with the DORT code and the BUGLE-96 cross-section library that is based on ENDF/B-VI evaluations. The calculations agreed with the measurements within 10%, and the calculations underpredicted the measurements in all the cases. This indicates that the ENDF/B-VI cross sections resolve most of the discrepancies between the measurements and calculations. The decrease of the CIM ratios with increased thickness of iron, which was typical for pre-ENDF/B-VI libraries, is almost completely removed
Near-field chemistry of the spent nuclear fuel repository
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)
Near-field radiative heat transfer in mesoporous alumina
The thermal conductivity of mesoporous material has aroused the great interest of scholars due to its wide applications such as insulation, catalyst, etc. Mesoporous alumina substrate consists of uniformly distributed, unconnected cylindrical pores. Near-field radiative heat transfer cannot be ignored, when the diameters of the pores are less than the characteristic wavelength of thermal radiation. In this paper, near-field radiation across a cylindrical pore is simulated by employing the fluctuation dissipation theorem and Green function. Such factors as the diameter of the pore, and the temperature of the material are further analyzed. The research results show that the radiative heat transfer on a mesoscale is 2∼4 orders higher than on a macroscale. The heat flux and equivalent thermal conductivity of radiation across a cylindrical pore decrease exponentially with pore diameter increasing, while increase with temperature increasing. The calculated equivalent thermal conductivity of radiation is further developed to modify the thermal conductivity of the mesoporous alumina. The combined thermal conductivity of the mesoporous alumina is obtained by using porosity weighted dilute medium and compared with the measurement. The combined thermal conductivity of mesoporous silica decreases gradually with pore diameter increasing, while increases smoothly with temperature increasing, which is in good agreement with the experimental data. The larger the porosity, the more significant the near-field effect is, which cannot be ignored. (paper)
Calculations of pressure wave bursts in steam pipes
Using as an example the live steam system of a boiling water reactor, the pressure wave propagation phenomena resulting from turbine trips in response to the by-pass system are described. The results of a previous calculation, using linearised characteristics methods are compared with those of a calculation using a differential procedure based on results of measurements. In a second example the periodic operation of safety valves of the steam generating system of a sodium cooled reactor is studied. (orig.)
Preliminary near-field environment report
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
Effective Algorithm for Calculation of Minimum Miscibility Pressure
Jessen, Kristian; Michelsen, Michael Locht; Stenby, Erling Halfdan
1998-01-01
This paper describes a new algorithm developed for calculation of the minimum miscibility pressure (MMP) for the displacement of oil by a multicomponent injection gas. The algorithm is based on the key tie line identification approach initially studied by Wang and Orr . A new global formulation i...
Effective Algorithm for Calculation of Minimum Miscibility Pressure
Jessen, Kristian; Michelsen, Michael Locht; Stenby, Erling Halfdan
This paper describes a new algorithm developed for calculation of the minimum miscibility pressure (MMP) for the displacement of oil by a multicomponent injection gas. The algorithm is based on the key tie line identification approach initially studied by Wang and Orr . A new global formulation i...
Calculation of vapor pressure of fission product fluorides and oxyfluorides
The equilibrium diagrams of the condensed phases - solid and liquid - and vapor phase are collected for the principal fluorides and oxyfluorides of fission product elements (atomic number from 30 to 66). These diagrams are used more particularly in fuel reprocessing by fluoride volatility process. Calculations and curves (vapor pressure in function of temperature) are processed using a computer program given in this report
Wind turbine sound pressure level calculations at dwellings.
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
Pressure calculation in hybrid particle-field simulations.
Milano, Giuseppe; Kawakatsu, Toshihiro
2010-12-01
In the framework of a recently developed scheme for a hybrid particle-field simulation techniques where self-consistent field (SCF) theory and particle models (molecular dynamics) are combined [J. Chem. Phys. 130, 214106 (2009)], we developed a general formulation for the calculation of instantaneous pressure and stress tensor. The expressions have been derived from statistical mechanical definition of the pressure starting from the expression for the free energy functional in the SCF theory. An implementation of the derived formulation suitable for hybrid particle-field molecular dynamics-self-consistent field simulations is described. A series of test simulations on model systems are reported comparing the calculated pressure with those obtained from standard molecular dynamics simulations based on pair potentials. PMID:21142296
Pressure calculation in hybrid particle-field simulations
In the framework of a recently developed scheme for a hybrid particle-field simulation techniques where self-consistent field (SCF) theory and particle models (molecular dynamics) are combined [J. Chem. Phys. 130, 214106 (2009)], we developed a general formulation for the calculation of instantaneous pressure and stress tensor. The expressions have been derived from statistical mechanical definition of the pressure starting from the expression for the free energy functional in the SCF theory. An implementation of the derived formulation suitable for hybrid particle-field molecular dynamics-self-consistent field simulations is described. A series of test simulations on model systems are reported comparing the calculated pressure with those obtained from standard molecular dynamics simulations based on pair potentials.
Near Field Communication: Technology and Market Trends
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.
Fourier optics and near-field superlens
Sheng, Yunlong; Tremblay, Guillaume; Gravel, Yann
2011-10-01
Fundamental Fourier optics is applied to metallic near-field superlens, whose transfer function is computed with the transfer matrix, the Surface Plasmon Polariton (SPP) resonance and the SPP waveguide theory. However, when the object nano-structure consists of feature nano-slits and nano-holes etc, which are as the basic object elements to scatter the light, especially when the objects are metal, the electrical dipoles are induced at the nano-slits and nano-holes by the illuminating light, the space invariance condition can be not respected within the dimension of the nano-meter scale objects, so that the point spread function becomes approximate and the superlens is usually characterized by the image of a two nano-slit pattern. The superlens is designed and optimized based on the transfer function. Improvement in the transfer function can improve significantly the image quality. The real image of the near-field superlens can be computed with numerical simulation using the FDTD method.
Convergence analysis in near-field imaging
This paper is devoted to the mathematical analysis of the direct and inverse modeling of the diffraction by a perfectly conducting grating surface in the near-field regime. It is motivated by our effort to analyze recent significant numerical results, in order to solve a class of inverse rough surface scattering problems in near-field imaging. In a model problem, the diffractive grating surface is assumed to be a small and smooth deformation of a plane surface. On the basis of the variational method, the direct problem is shown to have a unique weak solution. An analytical solution is introduced as a convergent power series in the deformation parameter by using the transformed field and Fourier series expansions. A local uniqueness result is proved for the inverse problem where only a single incident field is needed. On the basis of the analytic solution of the direct problem, an explicit reconstruction formula is presented for recovering the grating surface function with resolution beyond the Rayleigh criterion. Error estimates for the reconstructed grating surface are established with fully revealed dependence on such quantities as the surface deformation parameter, measurement distance, noise level of the scattering data, and regularity of the exact grating surface function. (paper)
Near Field Environment Process Model Report
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.
Chemistry of the near field environment
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
Lift-Off Acoustics Prediction of Clustered Rocket Engines in the Near Field
Vu, Bruce; Plotkin, Ken
2010-01-01
This slide presentation presents a method of predicting acoustics during lift-off of the clustered rocket engines in the near field. Included is a definition of the near field, and the use of deflectors and shielding. There is discussion about the use of PAD, a software system designed to calculate the acoustic levels from the lift of of clustered rocket enginee, including updates to extend the calculation to directivity, water suppression, and clustered nozzles.
Magnetic dipole moment determination by near-field analysis
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.
Calculation of reactor pressure vessel fluence using TORT code
TORT is employed for fast neutron fluence calculation at the reactor pressure vessel. KORI Unit 1 reactor at cycle 1 is modeled for this calculation. Three-dimensional cycle averaged assembly power distributions for KORI Unit 1 at cycle 1 are calculated by using the core physics code, NESTLE 5.0. The root mean square error is within 4.3% compared with NDR (Nuclear Design Report) for all burnup steps. The C/E (Calculated/Experimental) values for the in-vessel dosimeters distribute between 0.98 and 1.36. The most updated cross-section library, BUGLE-96 based on ENDF/B-VI is used for the neutron fluence calculation. The maximum fast neutron fluence calculated on reactor pressure vessel for KORI Unit 1 operated for 411.41 effective full power days is 1.784x1018n/cm2. The position of the maximum neutron fluence in RPV wall 1/4 T is nearby 60 cm below the midplane at zero degree
Near-Field Microscopy Studies of Lung Surfactant Collapse
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.
Calculations of plastic collapse load of pressure vessel using FEA
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.
Multiple-correlations improve well pressure-loss calculations
Mawla, A.M.A.; Darwich, T.; Sayyouh, M.H.; Abdel-Fattah, K. [Cairo Univ. (Egypt)
1996-09-09
Different correlations applied to each segment of a well bore provide better pressure-loss estimates than a single-correlation for the entire well. Four widely used multiphase-flow correlations have been defined on superficial velocities maps. No correlation can be satisfactorily applied in the transition region from bubble to slug regimes. To develop and verify this approach, actual field multiphase-flow data points were obtained from different naturally flowing and gas lifted oil wells in four different Gulf of Suez fields. After testing various pressure-volume-temperature (PVT) correlations against actual PVT data, the best correlations for different PVT properties for each particular field were identified. These best correlations, subsequently were used to calculate multiphase-flow pressure drop. The error analysis of different multiphase-flow correlations has been related to the in situ flowing conditions. The applicable ranges of the most widely used correlations have been defined on two-dimensional superficial velocity maps.
Numerical Calculation on Cavitation Pressure Pulsation in Centrifugal Pump
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...
Evaluation of long-term mechanical stability of near field
In the near field, as tunnels and pits are excavated, a redistribution of stresses in the surrounding rock will occur. For a long period of time after the emplacement of waste packages various events will take place, such as the swelling of the buffer, sinking of the overpack under its own weight, deformation arising from expansion of overpack corrosion products and the creep deformation of the rock mass. The evaluation of what effects these changes in the stress-state will have on the buffer and rock mass is a major issue from the viewpoint of safety assessment. Therefore, rock creep analysis, overpack corrosion expansion analysis and overpack sinking analysis have been made in order to examine the long-term mechanical stability of the near field and the interaction of various events that may affect the stability of the near field over a long period of time. As the results, rock creep behavior, the variations of the stress-state and the range of the influence zone differ from the rock strength, strength of buffer in the tunnel and side pressure coefficient etc. about the hard rock system and soft rock system established as basic cases. And the magnitude of the stress variations for buffer by the overpack sinking and rock creep deformation is negligible compared with it by the overpack corrosion expansion. Furthermore, though very limited zone of buffer around the overpack is close to the critical state by the overpack corrosion expansion, the engineered barrier system attains a comparatively stable state for a long period of time. (author)
A subdivision algorithm for phase equilibrium calculations at high pressures
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.
A Study of a Powder Coating Gun near Field: A Case of Staggered Concentric Jet Flow
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.
An investigation of in-flight near-field propeller noise generation and transmission
Bonneau, H.; Wilford, D. F.; Wood, L. K.
1985-02-01
In flight near field propeller noise measurements, made on a General Aviation turboprop aircraft, are reported for a range of propeller operating conditions, and are shown to be well defined and reproducible. Measurements have been made at 8 exterior microphones, 2 located on a wing mounted boom, and 6 embedded in, and flush with the aircraft fuselage. Interior noise levels are also presented. Measured propeller harmonic levels are compared to first principle calculations of near field noise, using a modified version of the Farassat computer program, in which the blade surface pressure is described using the known aerodynamic properties of the blade (NACA 16) airfoil sections. The first few; i.e., the dominant harmonic levels of propeller noise are shown to be well predicted, while higher harmonic levels are underpredicted. The transmission loss between exterior and interior noise levels is shown to be relatively constant for varying propeller operating conditions and at two different locations along the length of the fuselage. Interior noise levels are also shown for the aircraft in gliding flight at various forward velocities, with both engines at idle and propellers feathered. A method of interpolating these measurements is discussed, which allows the interior noise due only to the forward velocity of the aircraft, to be determined. The transmission loss for this component is also discussed. Finally, interior noise levels are presented for a series of ground static tests with engine mounts of various different stiffnessses.
The Survey on Near Field Communication
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.
The role of pressure flattening in calculating tearing mode stability
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
Improving convergence rates for low pressure material processing calculations
Moen, C.D.
1996-12-01
An enhanced solution strategy for the SIMPLER algorithm is presented for low pressure heat and mass transport calculations with applications in material processing. The accurate solution of highly diffusive flows requires an inflow boundary condition that preserves chemical species mass fluxes. The flux-preserving inflow boundary condition contains a scaling problem that causes the species equations to converge very slowly when using the standard SIMPLER algorithm. A gradient algorithm, coupled to a line-relaxation method, accelerates the convergence of the linear problem. Reformulation of the pressure-correction boundary conditions ensures that continuity is preserved in each finite volume at each iteration. The boundary condition scaling problem is demonstrated with a simple linear model problem. The enhanced solution strategy is implemented in a baseline computer code that is used to solve the multicomponent Navier-Stokes equations on a generalized, multiple-block grid system. Convergence rate acceleration factors of up to 100 are demonstrated for several material processing example problems.
Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane
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.
Signal of microstrip scanning near-field optical microscope in far- and near-field zones.
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
Theoretical and experimental examination of near-field acoustic levitation.
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
Uncertainty analysis of two-phase flow pressure drop calculations
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)
Popa, Paula Irina; Pivnenko, Sergey; Breinbjerg, Olav
2015-01-01
antenna diagnostics and perform a detailed systematic study of the extreme near-field of a standard gain horn at 60GHz from planar and spherical near-field measurement data. The magnitude and phase of all three rectangular components of the electric and the magnetic aperture fields are calculated, as is......We previously demonstrated that 60 GHz planarnear-field antenna measurements without external frequency conversion can provide far-field radiation patterns in good agreement with spherical near-field antenna measurements in spite of thecable flexing and thermal drift effects [P.I.Popa, S. Pivnenko......,J.M. Nielsen, O. Breinbjerg, 60 GHz Antenna Measurement Setup using a VNA without External Frequency Conversion,36th Annual Symposium of the Antenna Measurement Technique Association ,October 12-17,Tucson, Arizona, 2014]. In this work we extend the validation of this 60 GHz planar near-field (PNF) set-up to...
Distinct element method modeling of fracture behavior in near field rock
This report concerns the numerical calculations of the behavior of the near field of a nuclear waste repository. The calculations were performed using the two-dimensional distinct element code UDEC. The distinct element method accounts specifically for discontinuities, e.g. fractures that intersect the model region. It is shown that, if an appropriate joint constitutive relation is applied, the calculated joint behavior can be brought in close agreement with empirically derived stress-strain relations. Three basic geometries are studied, namely a vertical tunnel section, a horizontal borehole section and a combination, i.e. a vertical section of tunnel and deposition hole. The effects of different processes and activities are investigated, e.g. effects of excavations, of thermal loads, of internal tunnel pressures and of pore pressures and fracture flow resulting from the hydraulic ground water pressure. The interpretation of the results concerns in particular joint behavior, especially joint openings, in the nearest surroundings of excavations and of thermally affected regions. The calculations show that joint shear and joint normal displacements induced by excavation and by thermal processes may be considerable, and that thermal cycles may result in residual joint aperture changes, especially in systems with loosely bound rock blocks. It is concluded that the UDEC code, when applied to problems that have a two-dimensional character, gives results that are probably quantitatively correct. The results appear to be strongly dependant on the detailed joint structure close to free boundaries such as tunnel walls, which indicated that the 3-D situation regarding joint orientation might have to be considered. It is recommended that 3-D calculations should be performed to verify and quantitatively interpret the 2-D results and to analyze situations that are actually three-dimensional. (au)
Novel concepts in near-field optics: from magnetic near-field to optical forces
Yang, Honghua
Driven by the progress in nanotechnology, imaging and spectroscopy tools with nanometer spatial resolution are needed for in situ material characterizations. Near-field optics provides a unique way to selectively excite and detect elementary electronic and vibrational interactions at the nanometer scale, through interactions of light with matter in the near-field region. This dissertation discusses the development and applications of near-field optical imaging techniques, including plasmonic material characterization, optical spectral nano-imaging and magnetic field detection using scattering-type scanning near-field optical microscopy (s-SNOM), and exploring new modalities of optical spectroscopy based on optical gradient force detection. Firstly, the optical dielectric functions of one of the most common plasmonic materials---silver is measured with ellipsometry, and analyzed with the Drude model over a broad spectral range from visible to mid-infrared. This work was motivated by the conflicting results of previous measurements, and the need for accurate values for a wide range of applications of silver in plasmonics, optical antennas, and metamaterials. This measurement provides a reference for dielectric functions of silver used in metamaterials, plasmonics, and nanophotonics. Secondly, I implemented an infrared s-SNOM instrument for spectroscopic nano-imaging at both room temperature and low temperature. As one of the first cryogenic s-SNOM instruments, the novel design concept and key specifications are discussed. Initial low-temperature and high-temperature performances of the instrument are examined by imaging of optical conductivity of vanadium oxides (VO2 and V2O 3) across their phase transitions. The spectroscopic imaging capability is demonstrated on chemical vibrational resonances of Poly(methyl methacrylate) (PMMA) and other samples. The third part of this dissertation explores imaging of optical magnetic fields. As a proof-of-principle, the magnetic
Metrology of Electromagnetic Intensity Measurement in Near Field
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
Dielectric versus topographic contrast in near-field microscopy
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)....
Point-by-point near-field optical energy deposition around plasmonic nanospheres in absorbing media.
Harrison, R K; Ben-Yakar, Adela
2015-08-01
Here we investigate the effects of absorbing media on plasmon-enhanced near-field optical energy deposition. We find that increasing absorption by the medium results in increased particle scattering at the expense of particle absorption, and that much of this increased particle scattering is absorbed by the medium close to the particle surface. We present an analytical method for evaluating the spatial distribution of near-field enhanced absorption surrounding plasmonic metal nanospheres in absorbing media using a new point-by-point method. We propose criteria to define relevant near-field boundaries and calculate the properties of the local absorption enhancement, which redistributes absorption to the near-field and decays asymptotically as a function of the distance from the particle to background levels. Using this method, we performed a large-scale parametric study to understand the effect of particle size and wavelength on the near-field absorption for gold nanoparticles in aqueous media and silicon, and identified conditions that are relevant to enhanced local infrared absorption in silicon. The presented approach provides insight into the local energy transfer around plasmonic nanoparticles for predicting near-field effects for advanced concepts in optical sensing, thin-film solar cells, nonlinear imaging, and photochemical applications. PMID:26367296
Calculations of quasi-particle spectra of semiconductors under pressure
Christensen, Niels Egede; Svane, Axel; Cardona, M.;
2011-01-01
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 and the...... QSGW and LDA+U approximations are compared. For PbX the spinorbit coupling is included, and it is shown that although LDA gives a reasonable magnitude of the gap at L, only QSGW predicts the correct order of the L+6 and L-6 states and thus the correct sign (negative) of the gap pressure coefficient...
Ultrafast infrared near-field molecular nano-spectroscopy
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.
Near-Field Optical Microscopy of Fractal Structures
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...
Heat flux splitter for near-field thermal radiation
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.
Heat flux splitter for near-field thermal radiation
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.
Near field imaging from multilayer lens.
Li, Guixin; Li, Jensen; Tam, H L; Chan, C T; Cheah, K W
2011-12-01
Multilayer superlens has been reported that it had advantages over the single metal layer superlens. In this work, single silver layer and Ag-SiO2 multilayer superlens devices working at wavelength of 365 nm were fabricated using standard photolithography method. Grating objects with line/space (190 nm/190 nm) resolution could be resolved through both kinds of lens structures with working distance up to 128 nm. However, Ag-SiO2 multilayer lens shows higher transmittance and image contrast than the single silver layer device, the experimental result proves the theoretical calculation. PMID:22408982
Near field characteristics of buoyant helium plumes
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.
Improved image quality of a Ag slab near-field superlens with intrinsic loss of absorption.
Lee, Kwangchil; Park, Haesung; Kim, Jaehoon; Kang, Gumin; Kim, Kyoungsik
2008-02-01
Intrinsic loss of absorption in the Ag slab near-field superlens turned out to add a blurring effect to the ideal image reconstruction for the impedance match case. By optimizing the real part of the permittivity (epsilon') of Ag, our FDTD calculation predicts approximately 69% enhancement of visibility and approximately 138% increased depth of field for the intensity contrast of 0.5 with similar focal spot size. For a near-field superlens with the higher absorption loss, the optimized image quality is obtained with a larger impedance mismatch, which can be realized by changing the wavelength of incident light for imaging. PMID:18542250
Intracavity near-field optical imaging of a mid-infrared quantum cascade laser mode
We report the direct imaging of Fabry-Perot standing waves inside the cavity of a mid-infrared quantum cascade laser via apertureless scanning near-field optical microscopy. The quantum cascade devices employed present an evanescent wave at the top surface, whose magnitude is directly proportional to the cavity mode intensity in the device core region. Apertureless scanning near-field optical microscopy measurements provide experimental results about the nature of this evanescent field in good agreement with calculations (effective index and electric field decay length)
Intracavity near-field optical imaging of a mid-infrared quantum cascade laser mode
Lemoine, Paul-Arthur [Laboratoire d' Optique Physique, CNRS-UPR A0005, ESPCI, 75005 Paris (France); Moreau, Virginie; Bahriz, Michael [Institut d' Electronique Fondamentale, Universite Paris Sud, CNRS, 91405 Orsay (France); De Wilde, Yannick [Laboratoire d' Optique Physique, CNRS-UPR A0005, ESPCI, 75005 Paris (France)], E-mail: dewilde@optique.espci.fr; Colombelli, Raffaele [Institut d' Electronique Fondamentale, Universite Paris Sud, CNRS, 91405 Orsay (France)], E-mail: colombel@ief.u-psud.fr; Wilson, Luke R. [Department of Physics and Astronomy, University of Sheffield, Sheffield (United Kingdom); Krysa, Andrey B. [EPSRC National Centre for III-V Technologies, Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield (United Kingdom)
2008-04-15
We report the direct imaging of Fabry-Perot standing waves inside the cavity of a mid-infrared quantum cascade laser via apertureless scanning near-field optical microscopy. The quantum cascade devices employed present an evanescent wave at the top surface, whose magnitude is directly proportional to the cavity mode intensity in the device core region. Apertureless scanning near-field optical microscopy measurements provide experimental results about the nature of this evanescent field in good agreement with calculations (effective index and electric field decay length)
Near-field thermodynamics and nanoscale energy harvesting
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.
Near field enhancement in silver nanoantenna-superlens systems
Liu, Zhengtong; Li, Erping; Shalaev, Vladimir M.; Kildishev, Alexander V.
2012-07-01
We demonstrate near field enhancement generation in silver nanoantenna-superlens systems via numerical modeling. Using near-field interference and global optimization algorithms, we can design nanoantenna-superlens systems with mismatched permittivities, whose performance can match those with matched permittivities. The systems studied here may find broad applications in the fields of sensing, such as field-enhanced fluorescence and surface-enhanced Raman scattering, and the methodology used here can be applied to the designing and optimization of other devices, such as two-dimensional near field focusing lens.
Near-field microscopy through a SiC superlens.
Taubner, Thomas; Korobkin, Dmitriy; Urzhumov, Yaroslav; Shvets, Gennady; Hillenbrand, Rainer
2006-09-15
The wave nature of light limits the spatial resolution in classical microscopy to about half of the illumination wavelength. Recently, a new approach capable of achieving subwavelength spatial resolution, called superlensing, was invented, challenging the already established method of scanning near-field optical microscopy (SNOM). We combine the advantages of both techniques and demonstrate a novel imaging system where the objects no longer need to be in close proximity to a near-field probe, allowing for optical near-field microscopy of subsurface objects at sub-wavelength-scale lateral resolution. PMID:16973871
Resolution of objects within subwavelength range by using the near field of a dipole
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...
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.
The Basic Principle of the Near-Field Superlens
Kim, Kyoungsik
To overcome the diffraction limit in the optical imaging, the superlens with superresolution are developed using negative index materials. In this part, the basic principle of the near-field superlens is explained in details.
Principles of planar near-field antenna measurements
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.
Transfer functions in collection scanning near-field optical microscopy
Bozhevolnyi, Sergey I.; Vohnsen, Brian; Bozhevolnaya, Elena A.
1999-01-01
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....
Near-field and far-field goniophotometry of focused LED arrays
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.
Wideband scalable probe for Spherical Near-Field Antenna measurements
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 enable...... high-accuracy wideband antenna measurements at the DTU-ESA Spherical Near-Field Antenna Test Facility at frequencies down to 400 MHz....
Near field enhancement in silver nanoantenna-superlens systems
Liu, Zhengtong; Li, Erping; Shalaev, Vladimir M.; Kildishev, Alexander V.
2012-01-01
We demonstrate near field enhancement generation in silver nanoantenna-superlens systems via numerical modeling. Using near-field interference and global optimization algorithms, we can design nanoantenna-superlens systems with mismatched permittivities, whose performance can match those with matched permittivities. The systems studied here may find broad applications in the fields of sensing, such as field-enhanced fluorescence and surface-enhanced Raman scattering, and the methodology used ...
Non-contact transportation using near-field acoustic levitation
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
Near-field optics: The nightmare of the photon
Keller, Ole
2000-05-01
A first-quantized theory describing the birth process of a single photon in the near-field zone of a pointlike particle (atom, molecule, etc.) is established. The space-time description of the photon energy wave function embryo is shown to be useful for the understanding of the role played by (unborn) photons in near-field interactions where the spatial confinement of light plays a crucial role.
Near-Field Microwave Microscopy of Materials Properties
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 ...
Modeling Magnetic Near-Field Injection at Silicon Die Level
Boyer, Alexandre; Vrignon, Bertrand; Cavarroc, Manuel
2015-01-01
Near-field injection at silicon die level is a promising application for various area such as the analyses of integrated circuit (IC) susceptibility to electromagnetic interferences and security for cryptographic applications. This paper presents a first attempt to simulate the voltage induced on integrated circuit interconnects by a magnetic field probe. The validation of the simulation results is based on near-field injection performed on a test chip containing various types of interconnect...
Pan, Zhao; Whitehead, Jared; Thomson, Scott; Truscott, Tadd
2016-01-01
Obtaining pressure field data from particle image velocimetry (PIV) is an attractive technique in fluid dynamics due to its noninvasive nature. The application of this technique generally involves integrating the pressure gradient or solving the pressure Poisson equation using a velocity field measured with PIV. However, very little research has been done to investigate the dynamics of error propagation from PIV-based velocity measurements to the pressure field calculation. Rather than measur...
Scanning near-field infrared microscopy on semiconductor structures
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
Scanning near-field infrared microscopy on semiconductor structures
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
High energy photoelectron emission from gases using plasmonic enhanced near-fields
We study theoretically 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 excitation from mid-infrared laser pulses of current femtosecond oscillators. Typically, these fields appear in the surroundings of plasmonic nanostructures with various geometrical shapes, such as bow-ties, metallic waveguides, metal nanoparticles and nanotips, when illuminated by a short laser pulse. 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 spatial inhomogeneous 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 one-dimensional time-dependent Schrödinger equation to calculate the photoelectron emission of xenon atoms in such enhanced near-fields. Our findings are supported by classical calculations. (letter)
Near-field thermal emission between corrugated surfaces separated by nano-gaps
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. - Highlights: • FDTD calculations of LDOS are given for corrugated surfaces. • FDTD calculations of heat flux are given for corrugated surfaces. • CPML is used as the optimum boundary condition for this type of work. • Rectangular, elliptical and triangular shapes were used to form corrugated surfaces. • Rectangles proved to have the highest impact on enhancement of LDOS and heat flux
Study on Transient Properties of Levitated Object in Near-Field Acoustic Levitation
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.
Study on Transient Properties of Levitated Object in Near-Field Acoustic Levitation
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.
Calculation of minimum miscibility pressure using fast slimtube simulation
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 of st...... strategy is poroposed to reduce the number of slimtube simulations needed. In addition, it is also discussed how to parallelize slimtube simulations for modem computers with multiple CPU cores to further chop the computation time. Copyright 2012, Society of Petroleum Engineers....
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...
Modelling and closed loop control of near-field acoustically levitated objects
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...
THz near-field imaging of biological tissues employing synchrotronradiation
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.
Effects of a Near Field Pyroshock on the Performance of a Nitramine Nitrocellulose Propellant
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.
Effects of Near Field Pyroshock on the Performance of a Nitramine Nitrocellulose Propellant
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.
EARLY DETECTION OF NEAR-FIELD TSUNAMIS USING UNDERWATER SENSOR NETWORKS
L. E. Freitag; Xerandy,; M. Voortman; Znati, T.; L. K. Comfort
2012-01-01
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 d...
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.
A cascaded plasmonic superlens for near field imaging with magnification
Fu, Liwei; Schau, Philipp; Frenner, Karsten; Osten, Wolfgang
2015-06-01
In this report we exploit numerically a novel cascaded plasmonic superlens system for far field subwavelength imaging, which is a promising solution to the current existing problem with near field superlenses. In our approach, a metamaterial composed of a double layer metallic meander cavity (DLMC) structure is used to support the propagation of waves with large transverse wave vectors. Then a planar plasmonic lens (PPL) cascaded with the DLMC is used to couple the near field waves into free space to form an image with magnification via phase compensation. We study numerically the whole coupled system in the near and far field regime to demonstrate the functionality of such a superlens and near field interaction among them is discussed.
Near-field second-harmonic generation from gold nanoellipsoids
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.)
Near-Field Cross Section Imaging of Wideband Millimeter Wave
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.
Field of view for near-field aperture synthesis imaging
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.
LPA Beamformer for Tracking Nonstationary Accelerated Near-Field Sources
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.
Lang, Erhard W; Kasprowicz, Magdalena; Smielewski, Peter; Santos, Edgar; Pickard, John; Czosnyka, Marek
2016-01-01
This study investigates the outcome prediction and calculation of optimal cerebral perfusion pressure (CPPopt) in 307 patients after severe traumatic brain injury (TBI) based on cerebrovascular reactivity calculation of a moving correlation correlation coefficient, named PRx, between mean arterial pressure (ABP) and intracranial pressure (ICP). The correlation coefficient was calculated from simultaneously recorded data using different frequencies. PRx was calculated from oscillations between 0.008 and 0.05Hz and the longPRx (L-PRx) was calculated from oscillations between 0.0008 and 0.016 Hz. PRx was a significant mortality predictor, whereas L-PRx was not. CPPopt for pooled data was higher for L-PRx than for PRx, with no statistical difference. Mortality was associated with mean CPP below CPPopt. Severe disability was associated with CPP above CPPopt (PRx). These relationships were not statistically significant for CPPopt (L-PRx). We conclude that PRx and L-PRx cannot be used interchangeably. PMID:27165910
Near field communication recent developments and library implications
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
Near-field measurement of microwave active devices
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...
Percolation of optical excitation mediated by near-field interactions
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.
Near-field environment/processes working group summary
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.
Near-field mapping by laser ablation of PMMA coatings
Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter
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 subdiffractional topographic modifications on the surface which are quantified via scanning electron microscopy and atomic force microscopy...... the different stages in the ablation process can be controlled and characterized making the technique suitable for characterizing optical near-fields of metal nanostructures....
A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters
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.
Near-field thermal radiation between homogeneous dual uniaxial electromagnetic metamaterials
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.
Calculation of pressure wave inside the steam line with turbine trip
After turbine trip, a pressure wave phenomenon happens inside the steam lines and has disadvantageous effects on the steam generator and steam lines. To study this effect, the mathematical models for pressure wave calculation are developed and the calculating results are analyzed
Comparison of calculated and observed hydrostatic pressure measurements at borehole DC-8
Static water-level and fluid-pressure measurements are commonly converted in hydrologic studies to formation pressure and hydraulic head, which are used to determine groundwater flow characteristics of aquifer systems. For hydrologic studies that use hydraulic head and formation pressure data obtained from surface-based and downhole instruments, the relationship between water-level and downhole-pressure measurements must be established. This report presents the results of a field evaluation of 30 quartz pressure probes, which were used in the reference repository location baseline monitoring program. The pressure probes were field tested at a depth of 2,700.23 ft within borehole DC-8 between December 1984 and April 1985. Water-level measurements corrected for instrumental and noninstrumental errors were used in the HEADCO program to calculate the hydrostatic pressure at the fixed probe depth setting. HEADCO-calculated pressure values were then compared to the fluid-column pressure measured with each probe. Results of the field evaluation at the borehole DC-8 test facility indicate that recently calibrated pressure probes give consistent and comparable pressure measurements. In all cases, the difference between measured and calculated pressure values was less than the stated manufacturer accuracy range of +-1.2 lbf/in2. For the majority of the probes evaluated (i.e., 77%), the difference between observed and calculated pressures was 0.3 lbf/in2 or less. The close comparison of calculated and measured pressures also indicates that accurate downhole pressures can be calculated using water-level measurements and the HEADCO program, provided that systematic errors, due to borehole deviation, and thermal expansion and elastic deformation have been accounted for in the water-level measurements
Approximation for maximum pressure calculation in containment of PWR reactors
A correlation was developed to estimate the maximum pressure of dry containment of PWR following a Loss-of-Coolant Accident - LOCA. The expression proposed is a function of the total energy released to the containment by the primary circuit, of the free volume of the containment building and of the total surface are of the heat-conducting structures. The results show good agreement with those present in Final Safety Analysis Report - FSAR of several PWR's plants. The errors are in the order of ± 12%. (author)
A modified statistical methodology for rod internal pressure calculation
An existing statistical methodology for the nuclear fuel rod internal pressure(RIP) of the Korean PWR fuel has been modified in order to both reduce over-conservatism of the current KAERI deterministic methodology and simplify the complicated procedure of the existing statistical methodology which employs the response surface method and Monte Carlo simulation. The modified statistical methodology employs the system moment method combined with a deterministic approach in determining a maximum variance of RIP distribution. This approach makes the modified statistical methodology much more efficient in the routine reload design analysis since it eliminates the numerous processes required for the power history-dependent RIP variance derivations
Prediction of near field overpressure from quarry blasting
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...
Photon-induced near-field electron microscopy.
Barwick, Brett; Flannigan, David J; Zewail, Ahmed H
2009-12-17
In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved in both space (nanometre and below) and time (femtosecond). Here we report the development of photon-induced near-field electron microscopy (PINEM), and the associated phenomena. We show that the precise spatiotemporal overlap of femtosecond single-electron packets with intense optical pulses at a nanostructure (individual carbon nanotube or silver nanowire in this instance) results in the direct absorption of integer multiples of photon quanta (nhomega) by the relativistic electrons accelerated to 200 keV. By energy-filtering only those electrons resulting from this absorption, it is possible to image directly in space the near-field electric field distribution, obtain the temporal behaviour of the field on the femtosecond timescale, and map its spatial polarization dependence. We believe that the observation of the photon-induced near-field effect in ultrafast electron microscopy demonstrates the potential for many applications, including those of direct space-time imaging of localized fields at interfaces and visualization of phenomena related to photonics, plasmonics and nanostructures. PMID:20016598
COUPLEX2 test case modeling the near field
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)
Planar Near-Field Measurements of Ground Penetrating Radar Antennas
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...
Study of responsiveness of near-field terahertz imaging probes
Berta, Milan; Kužel, Petr; Kadlec, Filip
2009-01-01
Roč. 42, č. 15 (2009), 15550/1-15550/6. ISSN 0022-3727 R&D Projects: GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : microwave simulations * terahertz spectroscopy * near-field probe Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.083, year: 2009
Polarization singularities in near-field of Gaussian vortex beam diffracted by a circular aperture
Polarization singularities in the near-field of Gaussian vortex beams diffracted by a circular aperture are studied by a rigorous electromagnetic theory. It is shown that there exist C-points and L-lines, which depend on off-axis displacement parameters along the x and y directions, waist width, wavelength, and topological charge of the diffracted Gaussian vortex beam, as well as on propagation distance. The results are illustrated by numerical calculations. (classical areas of phenomenology)
Propagation of the electromagnetic field in fully coated near-field optical probes
Vaccaro, L; Aeschimann, L.; Staufer, U.; Herzig, Hans-Peter; Dändliker, René
2007-01-01
Fully metal-coated near-field optical probes, based on a cantilever design, have been studied theoretically and experimentally. Numerical simulations prove that these structures allow nonzero modal emission of the electromagnetic field through a 60-nm-thick metallic layer, that is opaque when deposited on flat substrates. The far-field intensity patterns recorded experimentally correspond to the ones calculated for the fundamental and first excited LP modes. Moreover, this study demonstrates ...
Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers
Jensen, Jørgen Arendt; Svendsen, Niels Bruun
1992-01-01
A method for simulation of pulsed pressure fields from arbitrarily shaped, apodized and excited ultrasound transducers is suggested. It relies on the Tupholme-Stepanishen method for calculating pulsed pressure fields, and can also handle the continuous wave and pulse-echo case. The field is calculated by dividing the surface into small rectangles and then Summing their response. A fast calculation is obtained by using the far-field approximation. Examples of the accuracy of the approach and a...
Cesium under pressure: First-principles calculation of the bcc-to-fcc phase transition
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.
Laminar and turbulent nozzle-jet flows and their acoustic near-field
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.
Karlsen, Andreas Grav
2014-01-01
Pressure changes due to Surge and Swabs has in many years been a big concern in the industry. If the pressure changes become too high, the formation can fracture, and formation influx can lead to a kick. In worst case scenarios this kick can lead on to blow out and put human life in danger. This thesis focuses the fundamental theory and on a program that can calculate the pressure changes in turbulent and laminar flow conditions for non-Newtonian fluids. The program lets you choose what secti...
Near-field tsunami forecasting using offshore tsunami data from the 2011 Tohoku earthquake
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
Numerical simulations of near-field blast effects using kinetic plates
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.
Flowing Bottomhole Pressure Calculation for a Pumped Well under Multiphase Flow
Bikbulatov, S; Zagurenko, A
2005-01-01
The ability to monitore bottomhole flowing pressure in pumping oil wells provides important information regarding both reservoir and artificial lift performance. Converting surface pressure measurements to bottomhole is currently accomplished by locating the fluid level in the annulus using a sonic device and then applying a correlation to estimate the density of the gas-cut liquid column above the perforations. This work proposes a flowing bottomhole pressure calculation procedure from fluid level measurements. The model is developed from experimental work and from theoretical arguments. The calculation procedure developed allows to calculate BHP without shutting the well, which is common for fluid level casinghead pressure measurements. Also this method allows to take into account real geometry of the The comparison of the calculated and measured pump intake pressure shows good accuracy of a technique. It allows to draw a conclusion for an opportunity to use this method in practice.
Calculation of coolant flow in a nuclear reactor pressure collector
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
First-principles calculations of a high-pressure synthesized compound PtC
Li, L. Y.; Yu, W; Jin, C. Q.
2005-01-01
First-principles density-functional method is used to study the recently high-pressure synthesized compound PtC. It is confirmed by our calculations that the platinum carbide has a zinc-blende ground-state phase at zero pressure and the rock-salt structure is a high-pressure phase. The theoretical transition pressure from zinc-blende to rock-salt is determined to be 52GPa. Furthermore, our calculation shows the possibility that the experimentally synthesized PtC by Ono et al. under high press...
An improved model for interface pressure calculations in free-surface flows
A new three-dimensional method for the calculation of interface pressure in the computational modeling of free surfaces and interfaces which use volume tracking methods is developed. This method is based on the calculation of the pressure force at the interfacial cell faces. The pressure forces at the interfacial cell faces are calculated according to the pressure imposed by each fluid on the portion of the cell face that is occupied by that fluid. Special formulations for the pressure in the interfacial cells are derived for different orientations of an interface. The present method, referred to as Pressure Calculation based on the Interface Location (PCIL), is applied to a three-dimensional motionless drop of liquid in an initially stagnant fluid with no gravity force. A two-fluid, PLIC-VOF method is used for numerical simulation of the flow. Both the Continuum Surface Force (CSF) and the Continuum Surface Stress (CSS) methods are used for surface tension calculations. A wide range of Ohnesorge numbers and density and viscosity ratios of the two fluids are tested. It is shown that the presence of spurious currents (artificial velocities present in case of considerable capillary forces) is mainly due to the inaccurate calculation of pressure forces on the interfacial cells. The new model reduces the spurious currents up to more than two orders of magnitude for the cases tested. (author)
Numerical Simulations of Blast Loads from Near-Field Ground Explosions in Air
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.
Near field and exit wave computations for electron microscopy
The partial wave phase shift formalism of atomic scattering is applied to compute exit wave functions for isolated Au and Si atoms under both plane wave and focused probe illumination. Connections between the far field and near field (exit) waves are clarified. This approach treats the Coulomb singularity properly though at 100 keV large numbers of phase shifts are required. In principle any form of incident wave can be handled so it may provide a means for testing traditional scattering theories used in electron microscopy. By applying the analysis to an atom embedded in a constant potential rather than free space, exit spheres of radius half the interatomic spacing can be used. - Highlights: • Critique of current theories of electron scattering in EM. • Near field and far field relationship. • Phase shift scattering theory adapted for exit wave computation. • Exit wave computations for an Au atom with plane and focused wave illumination
Active thermal extraction of near-field thermal radiation
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.
Transfer function and near-field detection of evanescent waves
Radko, Ylia P.; Bozhevolnyi, Sergey I.; Gregersen, Niels
2006-01-01
We consider characterization of a near-field optical probe in terms of detection efficiency of different spatial frequencies associated with propagating and evanescent field components. The former are both detected with and radiated from an etched single-mode fibertip, showing reciprocity of...... collection and illumination modes. Making use of a collection near-field microscope with a similar fiber tip illuminated by an evanescent field, we measure the collected power as a function of the field spatial frequency in different polarization configurations. Considering a two-dimensional probe...... configuration, numerical simulations of detection efficiency based on the eigenmode expansion technique are carried out for different tip apex angles. The detection roll-off for high spatial frequencies observed in the experiment and obtained during the simulations is fitted using a simple expression for the...
Nanorod near-field radiative heat exchange analysis
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.
Generation and near-field imaging of Airy surface plasmons
Minovich, Alexander; Janunts, Norik; Pertsch, Thomas; Neshev, Dragomir N; Kivshar, Yuri S
2011-01-01
We demonstrate experimentally the generation and near-field imaging of nondiffracting surface waves - plasmonic Airy beams, propagating on the surface of a gold metal film. The Airy plasmons are excited by an engineered nanoscale phase grating, and demonstrate significant beam bending over their propagation. We show that the observed Airy plasmons exhibit self-healing properties, suggesting novel applications in plasmonic circuitry and surface optical manipulation.
A near field 3D radar imaging technique
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
Photon-induced near-field electron microscopy
Barwick, Brett; Flannigan, David J.; Zewail, Ahmed H.
2009-01-01
In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved in both space (nanometre and below) a...
Use of Near Field Communication in emergency Rescue situations
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....
Acceleration of electrons in the near field of LH grills
Following experimental observations of localised heat flux on components magnetically connected to the radiating waveguides, the acceleration of electrons near Lower Hybrid antennas is investigated. A simple analytical model is developed to compute the dynamics of the particles in the near field approximation. It is found that Landau damping of the very high N// (20 // 2, the heat flux along the field lines (3.5 MW/m2) is easily manageable for the components connected to the antenna. (author)
Near-Field Photothermal Heating with a Plasmonic Nanofocusing Probe
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.
Baumeister, K. J.
1979-01-01
Direct calculation of the internal structure of a ducted noise source from farfield pressure measurements is regarded as an initial value problem, where the pressure and pressure gradient (farfield impedance) are assumed to be known along a line in the farfield. If pressure and impedance are known at the boundary of the farfield, the pressure can be uniquely determined in the vicinity of the inlet and inside the inlet ducting. A marching procedure is developed which, with this information obtained from measurements, enables a description of a ducted noise source. The technique uses a finite difference representation of the homogeneous Helmholtz equation.
Active Extraction of Near-field Thermal Radiation
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.
Near-field thermal electromagnetic transport: An overview
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.
Near-Field Source Localization by Using Focusing Technique
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.
Short presentation on some researches activities about near field earthquakes
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)
Near-field photometry for organic light-emitting diodes
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.
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.
Near-field mapping of three-dimensional surface charge poles for hybridized plasmon modes
Yu Huang
2015-10-01
Full Text Available We describe a new computational approach to mapping three-dimensional (3D surface charge poles and thus to determine complicated and hybridized plasmon modes in metallic nanostructures via finite element method (FEM calculations. 3D surface charge distributions at the near-field resonance energies are calculated directly using Gauss’ law. For a nanosphere dimer, we demonstrate that higher-order hybridized plasmon modes can be addressed clearly. As an improvement to conventional mapping approaches, this new approach provides a better understanding of comprehensive physical image of plasmonic systems necessary for fundamental studies and spectroscopy applications.
REFREP: a near-field model for a spent fuel repository
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
On the slow dynamics of near-field acoustically levitated objects under High excitation frequencies
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.
Pore pressure calculation of the UO{sub 2} high burnup structure
Gao, Lijun, E-mail: lijungaothu@gmail.com [Tsinghua University, 100084 Beijing (China); Science and Technology on Reactor System Design Technology Laboratory, P.O. Box 622-500, 610041 Chengdu (China); Chen, Bingde [Nuclear Power Institute of China, 610041 Chengdu (China); Xiao, Zhong [National Energy R and D Center on Advanced Nuclear Fuel, 610041 Chengdu (China); Jiang, Shengyao; Yu, Jiyang [Tsinghua University, 100084 Beijing (China)
2013-07-15
Highlights: • Pore pressure is calculated based on local burnup, density and porosity. • Ronchi's equations of state are used instead of van der Waals’ equation. • Pore pressure increases as HBS transformation begins and then stays constant. • A best approximated parameter used for pore pressure calculation is recommended. -- Abstract: UO{sub 2} high burnup structure has an important impact on fuel behavior, especially in case of reactivity initiated accident (RIA). Pore relaxation enhances local fuel swelling and puts additional load to the fuel cladding, which makes fuel more susceptible to pellet–cladding mechanical interaction induced failure. Therefore, pore pressure calculation becomes vital when evaluating the fuel failure. In this paper pore pressure is calculated as a function of pellet radial local burnup based on the basic characteristics of HBS using Ronchi's correlation. The results indicate that pore pressure will approach a stable value as HBS is developing. A best approximated C value of 55 N/m is recommended for pore pressure calculation.
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.
Flowing Bottomhole Pressure Calculation for a Pumped Well under Multiphase Flow
Bikbulatov, S.; Khasanov, M.; Zagurenko, A.
2005-01-01
The ability to monitore bottomhole flowing pressure in pumping oil wells provides important information regarding both reservoir and artificial lift performance. Converting surface pressure measurements to bottomhole is currently accomplished by locating the fluid level in the annulus using a sonic device and then applying a correlation to estimate the density of the gas-cut liquid column above the perforations. This work proposes a flowing bottomhole pressure calculation procedure from fluid...
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.
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 in...
Tecnique for probabilistic calculation of brittle fracture of power plant pressure vessels
Technique for probabilistic calculation of brittle fracture of power plant pressure vessels is presented. Effect of static spread in data on mechanical material properties, defect sizes and errors of nondestructive test means on the accuracy of brittle fracture time prediction is taken account of. Example of probabilistic calculation of nuclear reactor vessel fracture during its operation is given
P.Orea
2003-01-01
Full Text Available We have performed Monte Carlo simulations in the canonical ensemble of a hard-sphere fluid adsorbed in microporous media. The pressure of the adsorbed fluid is calculated by using an original procedure that includes the calculations of the pressure tensor components during the simulation. In order to confirm the equivalence of bulk and adsorbed fluid pressures, we have exploited the mechanical condition of equilibrium and performed additional canonical Monte Carlo simulations in a super system "bulk fluid + adsorbed fluid". When the configuration of a model porous media permits each of its particles to be in contact with adsorbed fluid particles, we found that these pressures are equal. Unlike the grand canonical Monte Carlo method, the proposed calculation approach can be used efficiently to obtain adsorption isotherms over a wide range of fluid densities and porosities of adsorbent.
Plasmonic lithography modeling and measurement of near-field distribution of plasmonic nano-aperture
Kim, Yongwoo; Kim, Seok; Jung, Howon; Jang, Jinhee; Lee, Jae Yong; Hahn, Jae W.
2012-03-01
In plasmonic nano lithography, a photoresist responds to the localized electric field which decays evanescently in the direction of depth. A simple analytic model is suggested to predict profiles of exposed and finally developed pattern with a finite contrast of photoresist. In this model, the developing process is revisited by accounting the variation of dissolution rate with respect to expose dose distribution. We introduce the concept of nominal developing thickness (NDT) to determine the optimized developing process fitting to the isointensity profile. Based on this model, we obtained three dimensional distribution of near-field of bowtie shaped plasmonic nano aperture in a metal film from the near-field lithography pattern profile. For the near-field exposure, we fabricated a nano aperture in a aluminum metal film which is coated on the contact probe tip. By illuminating 405 nm diode laser source, the positive type photoresist is exposed by the localized electric field produced by nano aperture. The exposed photoresist is developed by the TMAH based solution with a optimum NDT, which leads the developing march encounters the isoexposure contour at threshold dose. From the measurement of developed pattern profile with a atomic force microscope (AFM), the three-dimensional isoexposure (or iso-intensity) surface at the very near region from the exit plane of an aperture (depth: 5 ~ 50 nm) is profiled. Using the threshold dose of photoresist and exposure time, the absolute intensity level is also measured. The experimental results are quantitatively compared with the calculation of FDTD (finite- difference time-domain) method. Concerning with the error in exposure time and threshold dose value, the error in measurement of profile and intensity are less than 6% and 1%, respectively. We expect the lithography model described in this presentation allows more elaborated expectation of developed pattern profile. Furthermore, a methodology of mapping is useful for the
Comparison between centrifuge near-field model test and its numerical analysis
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)
无
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.
Near-Field Characterization of Optical Micro/Nanofibres
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.
Enhanced near-field resolution in midinfrared using metamaterials
Korobkin, Dmitriy; Urzhumov, Yaroslav; Shvets, Gennady
2006-03-01
We demonstrate that a negative-permittivity material (silicon carbide) sandwiched between two layers of positive-permittivity material (silicon oxide) can be used for enhancement of the resolution of near-field imaging via the superlensing effect. The resulting three-layer metamaterial is also shown to exhibit an enhanced transmission when its effective dielectric permittivity matches that of the vacuum. Experimental far-field diagnostics of the superlensing based on measuring transmission coefficients through the metal-coated superlens is implemented using Fourier-transformed infrared microscopy. Superlensing is shown to be a highly resonant phenomenon manifested in a narrow frequency range.
On the near field behavior of inclined negatively buoyant jets
Besalduch L.A.
2014-03-01
Full Text Available We have performed an experimental campaign in the laboratory on the near field behavior of inclined negatively buoyant jets, issuing from a circular sharp-edged orifice, in order to investigate the symmetry properties of this phenomenon. The velocity measurements were obtained via a non intrusive image analysis technique, namely Feature Tracking Velocimetry. We present here both first and second order statistics, showing that the asymmetry of inclined negatively buoyant jets cannot be considered only a far field feature of this phenomenon, as it arises very close to the release point.
Near field communication (NFC) from theory to practice
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
Simulation study of 'perfect lens' for near-field nanolithography
Guo, Xiaowei; Dong, Qiming; Liu, Yong
2011-09-01
The near-field perfect lens (NFPL) in imaging chrome gratings is investigated by using finite difference time domain (FDTD) method. The surface plasmon focused effect in and beneath the NFPL layer is demonstrated. The effects of the grating parameters and NFPL permittivity on image fidelity are explored. It is found that the excitation of surface plasmons results in frequency-increased images at large duty cycles and small imaginary part of NFPL permittivities. It is also shown that maximum intensity distributions on image plane occur at some specified pitches and duty cycles. The physics mechanisms are presented to explain these phenomena.
Wide angle near-field diffraction and Wigner distribution
Almeida, J B
2003-01-01
Free-space propagation can be described as a shearing of the Wigner distribution function in the spatial coordinate; this shearing is linear in paraxial approximation but assumes a more complex shape for wide-angle propagation. Integration in the frequency domain allows the determination of near-field diffraction, leading to the well known Fresnel diffraction when small angles are considered and allowing exact prediction of wide-angle diffraction. The authors use this technique to demonstrate evanescent wave formation and diffraction elimination for very small apertures.
Near-Field Optical control of Doughnut-Shaped Nanostructures
Dubrovkin, A M; Ortyl, E; Zielinska, S
2014-01-01
The application of a local near-field optical excitation can be used to control step-by-step the reshape of individual doughnut-shaped azopolymer nano-objects by varying the time of illumination demonstrating its promising performance as a functional nano-object. The possibility to provide both photoinduced reshaping opens a way to the fundamental study of size-dependent scaling laws of optical properties, photoinduced reshaping efficiency and nanoreactor or nanoresonator behavior at nanometer scale. As an example the nano-object is used to self-assembly polystyrene nanospheres in a supraball.
Laboratory measurement of a long term behavior in HLW near-field by centrifugal model test
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)
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.
Analytical evaluation of special numerical calculations of pressure waves in the fluid. Pt. 1
The practise of applying control calculations to the results of extensive numerical calculations in the field of scientific engineering is indispensable, especially with regard to safety assessments. Analytical methods are often best suited for this purpose. Furthermore, they allow developing a sound understanding of the physical processes involved. This also applies to several methods for determining the pressure behavior inside a fluid. In the present report, the results of calculations are checked by the method of the so-called one-dimensional wave propagation. It is presumed that the propagation of the pressure wave in a fluid-filled system can be closely approximated by a function which, in addition to time and other parameters depends only on the coordinate of the direction of wave propagation. Satisfactory approximations are obtained wherever the averaging of certain parameters in the direction perpendicular to the direction of propagation is sufficient with regard to the mathematical evaluation of essential effects. The examples presented in this report start with approximative descriptions of non-linear effects in pressure waves. Starting from a certain location and point in time, the pressure waves have a linear characteristic. This is because pressure pulses introduced into the fluid are usually dampened to a considerable extent. Going backward in time, perturbation calculations can then be carried out. Certain aspects of the resulting approximation are well suited to check the results of extensive numerical calculations. The comparisons presented show good to reasonable results. (orig./GL)
Real-time terahertz near-field microscope
Blanchard, F; Tanaka, T; Hirori, H; Tanaka, H; Kadoya, Y; Tanaka, K
2011-01-01
Terahertz (THz) waves have been significantly developed in the last fifteen years because of their great potential for applications in industrial and scientific communities1,2. The unique properties of THz waves as transparency for numerous materials and strong absorption for water-based materials are expected to broadly impact biosensing3 such as medical imaging4, chemical identifications5, and DNA recognition6. In particular, for accessing information within a scale comparable to the cell size where interactions between cell membrane and other organelle structures occur, micron size spatial resolution is required. Due to the large wavelength, however, the joint capability of THz near-field imaging with real-time acquisition, which is a highly desirable ability for observing real-time changes of in vivo sample, remains undone. Here, we report a real-time THz near-field microscope with a high dynamic range that can capture images of a 370 x 740 {\\mu}m2 area at 35 frames per second. We achieve high spatial res...
Near-field NanoThermoMechanical memory
In this letter, we introduce the concept of NanoThermoMechanical Memory. Unlike electronic memory, a NanoThermoMechanical memory device uses heat instead of electricity to record, store, and recover data. Memory function is achieved through the coupling of near-field thermal radiation and thermal expansion resulting in negative differential thermal resistance and thermal latching. Here, we demonstrate theoretically via numerical modeling the concept of near-field thermal radiation enabled negative differential thermal resistance that achieves bistable states. Design and implementation of a practical silicon based NanoThermoMechanical memory device are proposed along with a study of its dynamic response under write/read cycles. With more than 50% of the world's energy losses being in the form of heat along with the ever increasing need to develop computer technologies which can operate in harsh environments (e.g., very high temperatures), NanoThermoMechanical memory and logic devices may hold the answer
Surface wave multipath signals in near-field microwave imaging.
Meaney, Paul M; Shubitidze, Fridon; Fanning, Margaret W; Kmiec, Maciej; Epstein, Neil R; Paulsen, Keith D
2012-01-01
Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations. PMID:22566992
Unidirectional wireless power transfer using near-field plates
One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency
Unidirectional wireless power transfer using near-field plates
Imani, Mohammadreza F.; Grbic, Anthony
2015-05-01
One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency.
Unidirectional wireless power transfer using near-field plates
Imani, Mohammadreza F., E-mail: mohamad.imani@gmail.com [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Grbic, Anthony [Radiation Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)
2015-05-14
One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency.
Near-field thermoacoustic tomography of small animals
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.
Literature survey of redox reactions in the near field
This report presents a summary of literature survey about geochemical reactions which are important to evaluate the redox conditions in the near field rock mass and buffer. The results of literature survey are summarized as follows; Minerals including ferrous iron and organic materials in the rock mass are important reductants. Initial stage after closure of repository, oxygen will be consumed by pyrite, because the reaction rate between pyrite and oxygen is relatively fast. It is possible to estimate the redox capacity for reductants by rock (mineral)-water interaction experiment in a laboratory. And it is expected that the ferrous iron-rich rock and higher porosity rock may have bigger redox capacity. It is impossible to estimate the oxygen consumption rate by reductants such as minerals including ferrous iron. The rate law and rate constant for the oxidation reaction of ferrous iron in the solution are also determined. As a conclusion, it seems that we can evaluate kinetically the evolution of geochemical conditions in the near field rock mass and buffer by excavation of drifts, based on data derived from these existing literatures. (author)
Aerosol dynamics in near-field aircraft plumes
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.
Measurement of the depletion beam focal spot using near-field scanning optical microscopy probes
The submicron size doughnut shape focal spot, which is traditionally measured by scattering off a nanoparticle or a fluorescent bead, is measured for the first time by a near-field scanning optical microscopy (NSOM) fiber probe. Measurement results agree very well with calculations. This method offers superior repeatability, better control and is less time-consuming than the traditional method as the probes are mechanically protected by their insertion into fiber optic ferrules, which also greatly facilitates the alignment of the tip to the focal spot. (paper)
Abasi, Reza; Markley, Loïc; Eleftheriades, George V
2011-12-01
A linear array of closely spaced sound transducers is presented that can produce a subwavelength-focused intensity profile at a distance of a quarter wavelength. This work is related to research on super-resolution using metamaterials in both the acoustic and optical domains. It is designed using the principle of shifted beams, a near-field antenna array theory developed for the subwavelength focusing of electromagnetic waves. Once the spatial sound pattern is characterized for each source, the optimal weights for a minimum beam width can be calculated. An experiment operating at 4 kHz was able to successfully construct a super-focused beam. PMID:22225134
Calculation of coolant flow profile, pressure and temperature behind a blockage in a fuel assembly
Refinements of calculational technique for fluid profiles and pressure in fuel assemblies using the model of an anisotropic porous body are presented. Introduced are correction functions taking account of the dependence of components of resistance volume force on a local attack angle and anisotropy coefficient. By means of developed programs of calculating hydrodynamics and heat exchange behind a blockage determined are distributions of coolant Velocity, pressure and temperature when blocking the pass opening of the fuel assembly. Calculational results are presented in figures, where experimental curves are also given for comparison. The programs permit to determine coolant fluid profile with approximately 5 % accuracy, pressure profile with approximately 15 %, coolant temperature profile with approximately 10 %
High-pressure physical properties of magnesium silicate post-perovskite from ab initio calculations
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.
Wierzcholski, Krzysztof
2011-01-01
The paper deals with the calculations of the unsteady, impulsive pressure distributions, carrying capacities and friction forces under unsteady conditions in a super-thin layer of biological synovial fluid inside the slide biobearing gap limited by a spherical bone head. Unsteady and random flow conditions for the biobearing lubrication are given. Moreover, the numerical topology of pressure calculation for a difference method is applied. From a mathematical viewpoint the present method for the solution of the modified Reynolds equation allows this problem to be resolved by the partial recurrence nonhomogeneous equation of the second order with variable coefficients. To the best of the author knowledge, an adaptation of the known numerical difference method to the spherical boundary conditions applied during the pressure calculations for a human hip bonehead seems to be decisive. PMID:21500763
Stochastic impulsive pressure calculations for time dependent human hip joint lubrication.
Wierzcholski, Krzysztof
2012-01-01
The present paper is concerned with the calculation of the stochastic unsteady, impulsive pressure distributions and load carrying capacities in human hip joint for unsteady stochastic conditions, various standard deviations and Gaussian probability density function. The total changes of hydrodynamic pressure caused by viscoelastic synovial fluid properties are completely estimated. Calculations are performed in a super thin layer of biological synovial fluid inside the slide hip joint gap limited by a spherical bone head. Using a new unified operator of summation (UOS) method, the numerical topology of pressure calculation for a difference method is applied. From numerical standpoint the proposed method of solving modified hydrodynamic equations reduces this problem to resolving the partial recurrence non-homogeneous equation of second order with variable coefficients. PMID:23394099
In view of the problems of SDR and Tim-Coates models in calculating permeability using nuclear magnetic resonance logging data, based on the fact that nuclear magnetic resonance T2 distribution and capillary pressure curves reflect the reservoir pore structure, a method was presented to calculate reservoir permeability using nuclear magnetic resonance logging and capillary pressure data. The correlation between Swanson parameter and permeability was established by comparing 31 core samples which were measured by mercury penetration and nuclear magnetic resonance logging. Considering the problem that capillary pressure data are limited by their quantity, the good correlativity between T2 geometric mean value of lateral relaxation time of nuclear magnetic resonance and Swanson parameter can be used to determine the Swanson parameter and to calculate reservoir permeability consecutively. The processing of the data in well A yields a permeability closer to the result of core analysis, and this indicates the accuracy of the method. (authors)