Hall effects on MHD flow of heat generating/absorbing fluid through porous medium in a rotating parallel plate channel

Science.gov (United States)

Swarnalathamma, B. V.; Krishna, M. Veera

2017-07-01

We studied heat transfer on MHD convective flow of viscous electrically conducting heat generating/absorbing fluid through porous medium in a rotating channel under uniform transverse magnetic field normal to the channel and taking Hall current. The flow is governed by the Brinkman's model. The diagnostic solutions for the velocity and temperature are obtained by perturbation technique and computationally discussed with respect to flow parameters through the graphs. The skin friction and Nusselt number are also evaluated and computationally discussed with reference to pertinent parameters in detail.

Study of the strongly ionized medium in active galactic n ('Warm Absorber'): multi-wavelength modelling and plasma diagnostics in the X-ray spectral range

International Nuclear Information System (INIS)

Porquet, Delphine

1999-01-01

The so-called 'Warm Absorber' medium is observed in the central region of Active Galactic Nuclei and particularly in Seyfert l galaxies. lt is mainly characterized by O(VII) and O(VIII) absorption edges detected in the soft X-rays. Its study (modelization and observation) is an important key tool to understand Active Galactic Nuclei. The work presented here consists in modelling the Warm Absorber, and in developing X-ray spectroscopy diagnostics to constrain the physical parameters of any hot medium such as the Warm Absorber. The physical parameters of the Warm Absorber (density, temperature, ionization processes..) are difficult to determine only on the basis of present X-ray data. In particular, the value of the density cannot be derived only from the modelling of the resonance lines and of the soft X-ray absorption edges since there are almost insensitive to the density in the range of values expected for the Warm Absorber. lt is why we have developed diagnostic methods based on a multi-wavelength approach. The modelling is made with two complementary computational codes: PEGAS, and IRIS which takes into account the most accurate atomic data. With these two codes, we have modelled several types of plasma ionisation processes (photoionized plasmas and/or collisional). Results for the Warm Absorber were compared to multi-wavelength observations (mainly the optical iron coronal lines [Fe X] 6375 Angstroms, [Fe XI] 7892 Angstroms, and [Fe XIV] 5303 Angstroms). The proposed method has allowed to show that the Warm Absorber could be responsible of the emission of these lines totally or partially. All models of the Warm Absorber producing coronal line equivalent widths larger than observed were ruled out. This strongly constrains the physical parameters of the Warm Absorber, and particularly its density (n H ≥10 10 cm -3 ). The new generation of X-ray satellites (Chandra/AXAF, XMM...) will produce spectra at high spectral resolution and high sensitivity

Conceptual basis for calculations of absorbed-dose distributions

International Nuclear Information System (INIS)

Sinclair, W.K.; Rossi, H.H.; Alsmiller, R.G.; Berger, M.J.; Kellerer, A.M.; Roesch, W.C.; Spencer, L.V.; Zaider, M.A.

1991-01-01

The effects of radiation on matter are initiated by processes in which atoms and molecules of the medium are ionized or excited. Over a wide range of conditions, it is an excellent approximation to assume that the average number of ionizations and excitations is proportional to the amount of energy imparted to the medium by ionizing radiation in the volume of interest. The absorbed dose, that is, the average amount of energy imparted to the medium per unit mass, is therefore of central importance for the production of radiation effects, and the calculation of absorbed-dose distributions in irradiated media is the focus of interest of the present report. It should be pointed out, however, that even though absorbed dose is useful as an index relating absorbed energy to radiation effects, it is almost never sufficient; it may have to be supplemented by other information, such as the distributions of the amounts of energy imparted to small sites, the correlation of the amounts of energy imparted to adjacent sites, and so on. Such quantities are termed stochastic quantities. Unless otherwise stated, all quantities considered in this report are non-stochastic. 266 refs., 11 figs., 2 tabs

Review of Plasmonic Nanocomposite Metamaterial Absorber

Directory of Open Access Journals (Sweden)

Mehdi Keshavarz Hedayati

2014-02-01

Full Text Available Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon. These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented.

Experimental Study of Heat Energy Absorber with Porous Medium for Thermoelectric Conversion System

Directory of Open Access Journals (Sweden)

Tzer-Ming Jeng

2013-12-01

Full Text Available The thermoelectric conversion system usually consists of the heat absorber, the thermoelectric generator (TEG and the heat sink, while the heat absorber collects the heat to increase the temperature on the hot surface of TEG and enhances the generating electricity. This study experimentally investigated the performance of the brass-beads packed-bed heat absorber for the thermoelectric conversion system. The packed-bed heat absorber is installed in a square channel with the various flow orientation systems and the small ratio of channel width to bead diameter. The flow orientation systems included the straight flow and jet flow systems. This study showed the local and average heat transfer characteristics for various parameters. The experimental results can be the base of designs for the novel porous heat absorber of the thermoelectric conversion system.

MAGIICAT I. THE Mg II ABSORBER-GALAXY CATALOG

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Nikole M.; Churchill, Christopher W. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G.; Murphy, Michael T., E-mail: nnielsen@nmsu.edu [Swinburne University of Technology, Victoria 3122 (Australia)

2013-10-20

We describe the Mg II Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07 ≤ z ≤ 1.1) galaxies with measurements of Mg II λλ2796, 2803 absorption from their circumgalactic medium within projected distances of 200 kpc from background quasars. In this work, we present 'isolated' galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100 kpc and a line of sight velocity separation of 500 km s{sup –1}. We standardized all galaxy properties to the ΛCDM cosmology and galaxy luminosities, absolute magnitudes, and rest-frame colors to the B- and K-band on the AB system. We present galaxy properties and rest-frame Mg II equivalent width, W{sub r} (2796), versus galaxy redshift. The well-known anti-correlation between W{sub r} (2796) and quasar-galaxy impact parameter, D, is significant to the 8σ level. The mean color of MAGIICAT galaxies is consistent with an Sbc galaxy for all redshifts. We also present B- and K-band luminosity functions for different W{sub r} (2796) and redshift subsamples: 'weak absorbing' [W{sub r} (2796) < 0.3 Å], 'strong absorbing' [W{sub r} (2796) ≥ 0.3 Å], low redshift (z < (z)), and high redshift (z ≥ (z)), where (z) = 0.359 is the median galaxy redshift. Rest-frame color B – K correlates with M{sub K} at the 8σ level for the whole sample but is driven by the strong absorbing, high-redshift subsample (6σ). Using M{sub K} as a proxy for stellar mass and examining the luminosity functions, we infer that in lower stellar mass galaxies, Mg II absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.

Study of thermal neutron currents near cylindrical absorbers located in heavy water

International Nuclear Information System (INIS)

Simard, Y.N.

1973-01-01

The experiments reported involved determining the angular response of detectors to neutrons exterior to the surface of long cylindrical absorbers immersed in a scattering medium. The absorbers consisted of solid cylinders of copper, cadmium, or natural uranium in a fuel lattice, and combinations of copper and cadmium, as well as voided cylinders. The scattering (moderating) medium consisted of heavy water. (author)

Far-field Lorenz-Mie scattering in an absorbing host medium: Theoretical formalism and FORTRAN program

Science.gov (United States)

Mishchenko, Michael I.; Yang, Ping

2018-01-01

In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenz-Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.

Far-Field Lorenz-Mie Scattering in an Absorbing Host Medium: Theoretical Formalism and FORTRAN Program

Science.gov (United States)

Mishchenko, Michael I.; Yang, Ping

2018-01-01

In this paper we make practical use of the recently developed first-principles approach to electromagnetic scattering by particles immersed in an unbounded absorbing host medium. Specifically, we introduce an actual computational tool for the calculation of pertinent far-field optical observables in the context of the classical Lorenzâ€"Mie theory. The paper summarizes the relevant theoretical formalism, explains various aspects of the corresponding numerical algorithm, specifies the input and output parameters of a FORTRAN program available at https://www.giss.nasa.gov/staff/mmishchenko/Lorenz-Mie.html, and tabulates benchmark results useful for testing purposes. This public-domain FORTRAN program enables one to solve the following two important problems: (i) simulate theoretically the reading of a remote well-collimated radiometer measuring electromagnetic scattering by an individual spherical particle or a small random group of spherical particles; and (ii) compute the single-scattering parameters that enter the vector radiative transfer equation derived directly from the Maxwell equations.

Full-flow absorbers. Every centimetre counts

Energy Technology Data Exchange (ETDEWEB)

Berner, Joachim

2012-07-01

New absorbers with a maximised area for heat exchange with the thermal medium are significantly more efficient than the presently typical designs. Both the industry and researchers are working to revive an old idea. (orig.)

Scaling neutron absorbed dose distributions from one medium to another

International Nuclear Information System (INIS)

Awschalom, M.; Rosenberg, I.; Ten Haken, R.K.

1983-01-01

Central axis depth dose (CADD) and off-axis absorbed dose ratio (OAR) measurements were made in water, muscle and whole skeletal bone tissue-equivalent (TE) solutions, mineral oil, and glycerin with a clinical neutron therapy beam. These measurements show that, for a given neutron beam quality and field size, there is a universal CADD distribution at infinity if the depth in the phantom is expressed in terms of appropriate scaling lengths. These are essentially the kerma-weighted neutron mean free paths in the media. The method used in ICRU Report No. 26 to scale the CADD by the ratio of the densities is shown to give incorrect results. The OARs measured in different media at depths proportional to the respective mean free paths were also found to be independent of the media to a good approximation. Therefore, neutron beam CADDs and OARs may be measured in either TE solution (USA practice) or water (European practice), and having determined the respective scaling lengths, all measurements may be scaled from one medium to any other. It is recommended that for general treatment planning purposes, scaling be made to TE muscle with a density of 1.04 g cm -3 , since this value represents muscle and other soft tissues better than TE solution of density 1.07 g cm -3 . For such a transformation, relative measurements made in water are found to require very small corrections. Hence, it is further recommended that relative CADD and OAR measurements be performed in water because of its universality and convenience. Finally, a table of calculated scaling lengths is given for various neutron energy spectra and for various tissues and materials of practical importance in neutron dosimetry

An efficient absorbing system for spectrophotometric determination of nitrogen dioxide

Science.gov (United States)

Kaveeshwar, Rachana; Amlathe, Sulbha; Gupta, V. K.

A simple and sensitive spectrophotometric method for determination of atmospheric nitrogen dioxide using o-nitroaniline as an efficient absorbing, as well as diazotizing, reagent is described. o-Nitroaniline present in the absorbing medium is diazotized by the absorbed nitrite ion to form diazonium compound. This is later coupled with 1-amino-2-naphthalene sulphonic acid (ANSA) in acidic medium to give red-violet-coloured dye,having λmax = 545 nm. The isoamyl extract of the red azo dye has λmax = 530 nm. The proposed reagents has ≈ 100% collection efficiency and the stoichiometric ratio of NO 2:NO 2- is 0.74. The other important analytical parameters have been investigated. By employing solvent extraction the sensitivity of the reaction was increased and up to 0.03 mg m -3 nitrogen dioxide could be estimated.

Method for manufacture of neutron absorbing articles

International Nuclear Information System (INIS)

Owens, D.

1980-01-01

A one-step curing method for the manufacture of a neutron absorbing article which comprises irreversibly curing, in desired article form, a form-retaining mixture of boron carbide particles, curable phenolic resin in solid state and in particula te form and a minor proportion of a liquid medium, which boils at a temperature below 200*c., at an elevated temperature so as to obtain bonding of the irreversibly cured phenolic polymer resulting to the boron carbide particles and production of the neutron absorbing article in desired form

Measurement of beam driven hydrodynamic turbulence

International Nuclear Information System (INIS)

Norem, J.; Black, E.; Bandura, L.; Errede, D.; Cummings, M. A. C.

2003-01-01

Cooling intense muon beams in liquid hydrogen absorbers introduces kW of heating to the cold fluid, which will drive turbulent flow. The amount of turbulence may be sufficient to help cool the liquid, but calculations are difficult. We have used a 20 MeV electron beam in a water tank to look at the scale of the beam driven convection and turbulence. The density and flow measurements are made with schlieren and Ronchi systems. We describe the optical systems and the turbulence measured. These data are being used to calibrate hydrodynamic calculations of convection driven and forced flow cooling in muon cooling absorbers

Performance of an absorbing concentrating solar collectors

International Nuclear Information System (INIS)

Imadojemu, H.

1990-01-01

This paper reports on a comparison of the efficiency of an absorbing fluid parabolic trough concentrating solar collector and a traditional concentrating collector that was made. In the absorbing fluid collector, black liquid flows through a glass tube absorber while the same black liquid flows through a selective black coated copper tube absorber while the same black fluid flows through a selective black coated copper tube absorber in the traditional collector. After a careful study of the properties of available black liquids, a mixture of water and black ink was chosen as the black absorbing medium or transfer fluid. In the black liquid glass collector there is a slightly improved efficiency based on beam radiation as a result of the direct absorption process and an increase in the effective transmittance absorptance. At worst the efficiency of this collector equals that of the traditional concentrating collector when the efficiency is based on total radiation. The collector's reflecting surfaces were made of aluminum sheet, parabolic line focus and with cylindrical receivers. The ease of manufacture and reduced cost per unit energy collected, in addition to the clean and pollution free mode of energy conversion, makes it very attractive

In-phantom measurement of absorbed dose to water in medium energy x-ray beams

International Nuclear Information System (INIS)

Hohlfeld, K.

1996-01-01

Absorbed dose values in a water phantom derived by the formalism of the IAEA Code of Practice of Absorbed Dose Determination in Photon and Electron Beams are a few per cent higher than those based on the procedure following e.g. ICRU Report 23. The maximum deviation exceeds 10% at 100 kV tube potential. The correction factor needed to take into account the differences at the calibration in terms of air kerma free in air and at the measurement in the water phantom can be determined in different ways: In comparing the result of the absorbed dose measurement by means of the ionization chambers with an other, preferably fundamental method of measurement of absorbed dose in the water phantom or by evaluating all component parts of the correction factor separately. The values of the perturbation correction factor in the IAEA Code were determined in the former way by comparing against a graphite extrapolation chamber. A review is given on a recent re-evaluation using former values of the extrapolation chamber measurements and on new determinations using an absorbed dose water calorimeter, a method based on calculated and measured air kerma values and a method of combining the component factors to the overall correction factor. Recent results achieved by the different methods are compared and a change of the data of the IAEA Code is recommended. (author). 31 refs, 14 figs, 3 tabs

On the radiative effects of light-absorbing impurities on snowpack evolution

Science.gov (United States)

Dumont, M.; Tuzet, F.; Lafaysse, M.; Arnaud, L.; Picard, G.; Lejeune, Y.; Lamare, M.; Morin, S.; Voisin, D.; Di Mauro, B.

2017-12-01

The presence of light absorbing impurities in snow strongly decreases snow reflectance leading to an increase in the amount of solar energy absorbed by the snowpack. This effect is also known as impurities direct radiative effect. The change in the amount of energy absorbed by the snowpack modifies the temperature profile inside the snowpack and in turn snow metamorphism (impurities indirect radiative effects). In this work, we used the detailed snowpack model SURFEX/ISBA-Crocus with an explicit representation of snow light-absorbing impurities content (Tuzet et al., 2017) fed by medium-resolution ALADIN-Climate atmospheric model to represent dust and black carbon atmospheric deposition fluxes. The model is used at two sites: Col de Porte (medium elevation site in the French Alps) and Torgnon (high elevation site in the Italian Alps). The simulations are compared to in-situ observations and used to quantify the effects of light-absorbing impurities on snow melt rate and timing. The respective parts of the direct and indirect radiative effects of light-absorbing impurities in snow are also computed for the two sites, emphasizing the need to account for the interactions between snow metamorphism and LAI radiative properties, to accurately predict the effects of light-absorbing impurities in snow. Moreover, we describe how automated hyperspectral reflectance can be used to estimate effective impurities surface content in snow. Finally we demonstrate how these reflectances measurements either from in situ or satellite data can be used via an assimilation scheme to constrain snowpack ensemble simulations and better predict the snowpack state and evolution.

Electron scattering effects on absorbed dose measurements with LiF-dosemeters

International Nuclear Information System (INIS)

Bertilsson, G.

1975-10-01

The investigation deals with absorbed dose measurements with solid wall-less dosemeters. Electron scattering complicates both measurement of absorbed dose and its theoretical interpretation. The introduction of the dosemeter in a medium causes perturbations of the radiation field. This perturbation and its effect on the distribution of the absorbed dose inside the dosemeter is studied. Plane-parallel LiF-teflon dosemeters (0.005 - 0.1 g.cm -2 ) are irradiated by a photon beam ( 137 Cs) in different media. The investigation shows that corrections must be made for perturbations caused by electron scattering phenomena. Correction factors are given for use in accurate absorbed dose determinations with thermoluminescent dosemeters. (Auth.)

Advances in absorbed dose measurement standards at the australian radiation laboratory

International Nuclear Information System (INIS)

Boas, J.F.; Hargrave, N.J.; Huntley, R.B.; Kotler, L.H.; Webb, D.V.; Wise, K.N.

1996-01-01

The applications of ionising radiation in the medical and industrial fields require both an accurate knowledge of the amount of ionising radiation absorbed by the medium in question and the capability of relating this to National and International standards. The most useful measure of the amount of radiation is the absorbed dose which is defined as the energy absorbed per unit mass. For radiotherapy, the reference medium is water, even though the measurement of the absorbed dose to water is not straightforward. Two methods are commonly used to provide calibrations in absorbed dose to water. The first is the calibration of the chamber in terms of exposure in a Cobalt-60 beam, followed by the conversion by a protocol into dose to water in this and higher energy beams. The other route is via the use of a graphite calorimeter as a primary standard device, where the conversion from absorbed dose to graphite to absorbed dose in water is performed either by theoretical means making use of cavity ionisation theory, or by experiment where the graphite calorimeter and secondary standard ionisation chamber are placed at scaled distances from the source of the radiation beam (known as the Dose-Ratio method). Extensive measurements have been made at Cobalt-60 at ARL using both the exposure and absorbed dose to graphite routes. Agreement between the ARL measurements and those based on standards maintained by ANSTO and NPL is within ± 0.3%. Absorbed dose measurements have also been performed at ARL with photon beams of nominal energy 16 and 19 MeV obtained from the ARL linac. The validity of the protocols at high photon energies, the validity of the methods used to convert from absorbed dose in graphite to absorbed dose in water and the validity of the indices used to specify the beams are discussed. Brief mention will also be made of the establishment of a calibration facility for neutron monitors at ARL and of progress in the development of ERP dosimetry

Advances in absorbed dose measurement standards at the australian radiation laboratory

Energy Technology Data Exchange (ETDEWEB)

Boas, J.F.; Hargrave, N.J.; Huntley, R.B.; Kotler, L.H.; Webb, D.V.; Wise, K.N. [Australian Radiation Laboratory, Yallambie, VIC (Australia)

1996-12-31

The applications of ionising radiation in the medical and industrial fields require both an accurate knowledge of the amount of ionising radiation absorbed by the medium in question and the capability of relating this to National and International standards. The most useful measure of the amount of radiation is the absorbed dose which is defined as the energy absorbed per unit mass. For radiotherapy, the reference medium is water, even though the measurement of the absorbed dose to water is not straightforward. Two methods are commonly used to provide calibrations in absorbed dose to water. The first is the calibration of the chamber in terms of exposure in a Cobalt-60 beam, followed by the conversion by a protocol into dose to water in this and higher energy beams. The other route is via the use of a graphite calorimeter as a primary standard device, where the conversion from absorbed dose to graphite to absorbed dose in water is performed either by theoretical means making use of cavity ionisation theory, or by experiment where the graphite calorimeter and secondary standard ionisation chamber are placed at scaled distances from the source of the radiation beam (known as the Dose-Ratio method). Extensive measurements have been made at Cobalt-60 at ARL using both the exposure and absorbed dose to graphite routes. Agreement between the ARL measurements and those based on standards maintained by ANSTO and NPL is within {+-} 0.3%. Absorbed dose measurements have also been performed at ARL with photon beams of nominal energy 16 and 19 MeV obtained from the ARL linac. The validity of the protocols at high photon energies, the validity of the methods used to convert from absorbed dose in graphite to absorbed dose in water and the validity of the indices used to specify the beams are discussed. Brief mention will also be made of the establishment of a calibration facility for neutron monitors at ARL and of progress in the development of ERP dosimetry.

Quantification of Mycosphaerella fijiensis in vitro growth by absorbance readings

Directory of Open Access Journals (Sweden)

Mileidy Cruz-Martín

2013-10-01

Full Text Available The slow growth of Mycosphaerella fijiensis Morelet in synthetic and semi-synthetic media as well as the characteristics of their colonies makes the use of traditional methods for evaluating the fungal growth are inadequate and impractical. Therefore, it requires a method to quantify growth in small volumes of substance and in short periods of time. The aim of this study was to quantify the M. fijiensis growth, through absorbance readings on the time, of mycelial suspensions obtained from cultures in liquid medium. Mycelial dry weight of the pathogen grown in liquid culture in flasks of 250 ml capacity and the absorbance in 96 well plates was compared. Similar procedure was used to evaluate the effect of bacterial culture filtrates with in vitro antifungal activity against M. fijiensis. A linear relationship between absorbance at 595 nm of fungal growth in liquid culture medium with respect to the dry mass was found. Absorbance readings using 96-well plates were possible to quantify the M. fijiensis mycelial suspensions growth in liquid culture. Also, there may be applied to assess the growth inhibition of the pathogen for bacterial culture filtrates with results at 48 h incubation. Key words: antifungal activity assay, biomass, DO595

Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium

Energy Technology Data Exchange (ETDEWEB)

Rink, Alexandra; Lewis, David F.; Varma, Sangya; Vitkin, I. Alex; Jaffray, David A. [Princess Margaret Hospital/Ontario Cancer Institute, Department of Medical Biophysics and Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Advanced Materials Group, International Specialty Products, Inc., Wayne, New Jersey 07470 (United States); Princess Margaret Hospital/Ontario Cancer Institute, Department of Medical Biophysics and Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada)

2008-10-15

The effects of temperature on real time changes in optical density ({Delta}OD) of GAFCHROMIC EBT film were investigated. The spectral peak of maximum change in absorbance ({lambda}{sub max}) was shown to downshift linearly when the temperature of the film was increased from 22 to 38 degree sign C. The {Delta}OD values were also shown to decrease linearly with temperature, and this decrease could not be attributed to the shift in {lambda}{sub max}. A compensation scheme using {lambda}{sub max} and a temperature-dependent correction factor was investigated, but provided limited improvement. Part of the reason may be the fluctuations in hydration of the active component, which were found to affect both position of absorbance peaks and the sensitivity of the film. To test the effect of hydration, laminated and unlaminated films were desiccated. This shifted both the major and minor absorbance peaks in the opposite direction to the change observed with temperature. The desiccated film also exhibited reduced sensitivity to ionizing radiation. Rehydration of the desiccated films did not reverse the effects, but rather gave rise to another form of the polymer with absorbance maxima upshifted further 20 nm. Hence, the spectral characteristics and sensitivity of the film can be dependent on its history, potentially complicating both real-time and conventional radiation dosimetry.

Warm Absorber Diagnostics of AGN Dynamics

Science.gov (United States)

Kallman, Timothy

key for validating and testing models. New in this work is treatment of magnetically driven models, self-consistent calculation of the physical properties of the accretion flow and winds and their spectra. This will allow us to test the range of plausible physical origins for warm absorbers.

Kinetics of phototoxicity of Fischer's medium for L5178Y leukemic cells

International Nuclear Information System (INIS)

Griffin, F.M.; Ashland, G.; Capizzi, R.L.

1981-01-01

The uncontrolled exposure of Fischer's medium to cool white fluorescent (CWF) light or other sources emitting near-ultraviolet or visible light absorbance by riboflavin is a crucial random variable in experiments which utilize L5178Y cells and this medium. The radiation effects of CWF light result in the rapid development of toxic photoproducts in the medium which are cytostatic at lower doses of radiation and cytotoxic at higher doses. After a 24-hr suspension in medium irradiated for 3 or 48 hr, the cloning efficiencies of cells subsequently plated in light-protected medium were 87 and 3%, respectively. The corresponding near-ultraviolet doses for these periods of exposure to CWF light were 0.22 x 10(4) for a 3-hr exposure and 3.47 x 10(4) J/sq m for a 48-hr exposure. Cells incubated in lightly irradiated medium resumed growth at nearly normal rates following a 24- to 48-hr period in which no increase in cell numbers occurred. Exposure of medium containing riboflavin, but not tryptophan or tyrosine, to CWF light also produces toxic medium. Tryptophan enhances riboflavin-induced phototoxicity, whereas tyrosine diminishes this effect. As photosusceptibility of this system is very high, Fischer's medium must be fully protected from all sources of light absorbable by riboflavin

A linear analytical study of Soret-driven ferrothermohaline convection in an anisotropic porous medium

International Nuclear Information System (INIS)

Sekar, R.; Raju, K.; Vasanthakumari, R.

2013-01-01

The Soret-driven ferrothermoconvective instability of multi- component fluid in an anisotropic porous medium heated from below and salted from above has been analyzed using Brinkman model for various values of anisotropic parameter. The salinity effect is contained in magnetization and density of the ferrofluid and the system is assumed to have anisotropy in the vertical direction and isotropy in the horizontal direction. A small perturbation imparted on the basic state and a linear stability analysis is used for this model for which the normal mode technique is applied. The present analysis has been carried out through both stationary as well as oscillatory modes. The vertical anisotropy tends to destabilize the system. -- Highlights: ► We examine the effect of anisotropy and magnetization of convection in Soret effect. ► The system loses its stability for critical Rayleigh number for various parameters like R s and K 1 . ► The larger temperature difference is needed to guarantee the occurring of convection. ► The Soret effect plays a dominant role for the stability of the system

Photonic-resonant left-handed medium

International Nuclear Information System (INIS)

Shen Jianqi

2006-01-01

A new scheme to realize simultaneously negative permittivity and permeability in a coherent atomic vapor medium (photonic-resonant material) via a coherent driving mechanism is suggested. It is verified that the atomic system coherently driven by a strong optical field will give rise to a negative refractive index in certain probe frequency ranges. One of the most remarkable features of the present scheme is such that a slab fabricated by the left-handed vapor medium is an ideal candidate for designing perfect lenses since the photonic-resonant atomic vapor cannot only exhibit an isotropic negative refractive index, but also provide a good impedance match at the air-medium interfaces

Suppression of AGN-driven Turbulence by Magnetic Fields in a Magnetohydrodynamic Model of the Intracluster Medium

Science.gov (United States)

Bambic, Christopher J.; Morsony, Brian J.; Reynolds, Christopher S.

2018-04-01

We investigate the role of active galactic nucleus (AGN) feedback in turbulent heating of galaxy clusters. Specifically, we analyze the production of turbulence by g-modes generated by the supersonic expansion and buoyant rise of AGN-driven bubbles. Previous work that neglects magnetic fields has shown that this process is inefficient, with less than 1% of the injected energy ending up in turbulence. This inefficiency primarily arises because the bubbles are shredded apart by hydrodynamic instabilities before they can excite sufficiently strong g-modes. Using a plane-parallel model of the intracluster medium (ICM) and 3D ideal magnetohydrodynamics (MHD) simulations, we examine the role of a large-scale magnetic field that is able to drape around these rising bubbles, preserving them from hydrodynamic instabilities. We find that while magnetic draping appears better able to preserve AGN-driven bubbles, the driving of g-modes and the resulting production of turbulence is still inefficient. The magnetic tension force prevents g-modes from transitioning into the nonlinear regime, suppressing turbulence in our model ICM. Our work highlights the ways in which ideal MHD is an insufficient description for the cluster feedback process, and we discuss future work such as the inclusion of anisotropic viscosity as a means of simulating high β plasma kinetic effects. These results suggest the hypothesis that other mechanisms of heating the ICM plasma such as sound waves or cosmic rays may be responsible for the observed feedback in galaxy clusters.

Enhancing Localized Evaporation through Separated Light Absorbing Centers and Scattering Centers

Science.gov (United States)

Zhao, Dengwu; Duan, Haoze; Yu, Shengtao; Zhang, Yao; He, Jiaqing; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2015-01-01

This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems. PMID:26606898

Polydimethylsiloxane (PDMS) modulates CD38 expression, absorbs retinoic acid and may perturb retinoid signalling.

Science.gov (United States)

Futrega, Kathryn; Yu, Jianshi; Jones, Jace W; Kane, Maureen A; Lott, William B; Atkinson, Kerry; Doran, Michael R

2016-04-21

Polydimethylsiloxane (PDMS) is the most commonly used material in the manufacture of customized cell culture devices. While there is concern that uncured PDMS oligomers may leach into culture medium and/or hydrophobic molecules may be absorbed into PDMS structures, there is no consensus on how or if PDMS influences cell behaviour. We observed that human umbilical cord blood (CB)-derived CD34(+) cells expanded in standard culture medium on PDMS exhibit reduced CD38 surface expression, relative to cells cultured on tissue culture polystyrene (TCP). All-trans retinoic acid (ATRA) induces CD38 expression, and we reasoned that this hydrophobic molecule might be absorbed by PDMS. Through a series of experiments we demonstrated that ATRA-mediated CD38 expression was attenuated when cultures were maintained on PDMS. Medium pre-incubated on PDMS for extended durations resulted in a time-dependant reduction of ATRA in the medium and increasingly attenuated CD38 expression. This indicated a time-dependent absorption of ATRA into the PDMS. To better understand how PDMS might generally influence cell behaviour, Ingenuity Pathway Analysis (IPA) was used to identify potential upstream regulators. This analysis was performed for differentially expressed genes in primary cells including CD34(+) haematopoietic progenitor cells, mesenchymal stromal cells (MSC), and keratinocytes, and cell lines including prostate cancer epithelial cells (LNCaP), breast cancer epithelial cells (MCF-7), and myeloid leukaemia cells (KG1a). IPA predicted that the most likely common upstream regulator of perturbed pathways was ATRA. We demonstrate here that ATRA is absorbed by PDMS in a time-dependent manner and results in the concomitant reduced expression of CD38 on the cell surface of CB-derived CD34(+) cells.

The two-parametric scaling and new temporal asymptotic of survival probability of diffusing particle in the medium with traps.

Science.gov (United States)

Arkhincheev, V E

2017-03-01

The new asymptotic behavior of the survival probability of particles in a medium with absorbing traps in an electric field has been established in two ways-by using the scaling approach and by the direct solution of the diffusion equation in the field. It has shown that at long times, this drift mechanism leads to a new temporal behavior of the survival probability of particles in a medium with absorbing traps.

Self Absorbed Fraction for Electrons and Beta Particles in Small Spherical Volumes

International Nuclear Information System (INIS)

Grosev, D.

2003-01-01

Absorbed fraction and target organ mass are important parameters of internal dosimetry calculations that define the geometry of the system. Standard MIRD (Medical Internal Radiation Dosimetry) formalism assumes that the absorbed fraction for non-penetrating radiations (e.g., electrons, beta particles) is 1. This may not be correct in cases where dimensions of organs/tissues are comparable with the ranges of electrons/beta particles. Such is the case for example in radiodine ablation of thyroid remnant tissue. In this work the self-absorbed fraction (source and target volumes are the same) for monoenergetic electrons and beta particles is calculated for small spherical volumes of various sizes and unit density. Absorbed fraction can be expressed as an integral of the product of two quantities: (a) Scaled beta dose point kernel (mean absorbed dose rate per activity of the point source in infinite homogenous medium), F β ; (b) special geometrical reduction factor (GRF). F β is calculated using EGS4 Monte Carlo (MC) code for transport of electrons and photons. MC source code calculates the deposition of energy inside concentric spherical shells around the isotropic point source of electrons/beta particles in infinite medium (water). Shell thickness was δr=0.02·X 90 , where X 90 represents the radius of the sphere inside which 90% of the source energy is absorbed. Number of concentric spherical shells was 100, 10000 electron histories were started in each program run, and 10 runs were repeated for statistical reason. Numerical integration of the product of F β , calculated by MC program, and GRF for sphere was done using Simpson method. Absorbed fractions were calculated for spheres with mass from 0.01-20 g (r = 0.13 - 1.68 cm). Results are given for monoenergetic electrons with kinetic energy T=0.2, 0.4, 1.0 MeV, and for three beta emitters 1 31I , 3 2P , 9 0Y . For quantitative dosimetric protocols in radioiodine ablation therapy, results for 1 31I are of

Scaling neutron absorbed dose distributions from one medium to another

International Nuclear Information System (INIS)

Awschalom, M.; Rosenberg, I.; Ten Haken, R.K.

1982-11-01

Central axis depth dose (CADD) and off-axis absorbed dose ratio (OAR) measurements were made in water, muscle and whole skeletal bone TE-solutions, mineral oil and glycerin with a clinical neutron therapy beam. These measurements show that, for a given neutron beam quality and field size, there is a universal CADD distribution at infinity if the depth in the phantom is expressed in terms of appropriate scaling lengths. These are essentially the kerma-weighted neutron mean free paths in the media. The method used in ICRU No. 26 to scale the CADD by the ratio of the densities is shown to give incorrect results. the OAR's measured in different media at depths proportional to the respective mean free paths were also found to be independent of the media to a good approximation. It is recommended that relative CADD and OAR measurements be performed in water because of its universality and convenience. A table of calculated scaling lengths is given for various neutron energy spectra and for various tissues and materials of practical importance in neutron dosimetry

Wide band design on the scaled absorbing material filled with flaky CIPs

Science.gov (United States)

Xu, Yonggang; Yuan, Liming; Gao, Wei; Wang, Xiaobing; Liang, Zichang; Liao, Yi

2018-02-01

The scaled target measurement is an important method to get the target characteristic. Radar absorbing materials are widely used in the low detectable target, considering the absorbing material frequency dispersion characteristics, it makes designing and manufacturing scaled radar absorbing materials on the scaled target very difficult. This paper proposed a wide band design method on the scaled absorbing material of the thin absorption coating with added carbonyl iron particles. According to the theoretical radar cross section (RCS) of the plate, the reflection loss determined by the permittivity and permeability was chosen as the main design factor. Then, the parameters of the scaled absorbing materials were designed using the effective medium theory, and the scaled absorbing material was constructed. Finally, the full-size coating plate and scaled coating plates (under three different scale factors) were simulated; the RCSs of the coating plates were numerically calculated and measured at 4 GHz and a scale factor of 2. The results showed that the compensated RCS of the scaled coating plate was close to that of the full-size coating plate, that is, the mean deviation was less than 0.5 dB, and the design method for the scaled material was very effective.

Summary of the CERN Workshop on Materials for Collimators and Beam Absorbers

CERN Document Server

Schmidt, R; Bertarelli, A; Ferrari, A; Weterings, W; Mokhov, N V

2008-01-01

The main focus of the workshop was on collimators and beam absorbers for (mainly) High Energy Hadron Accelerators, with the energy stored in the beams far above damage limit. The objective was to better understand the technological limits imposed by mechanisms related to beam impact on materials. The idea to organise this workshop came up during the High Intensity High Brightness Hadron Beams, ICFA-HB2006 in Japan [1]. The workshop was organised 3-5 September 2007 at CERN, with about 60 participants, including 20 from outside CERN. About 30 presentations were given [2]. The event was driven by the LHC challenge, with more than 360 MJoule stored in each proton beam. The entire beam or its fraction will interact with LHC collimators and beam absorbers, and with the LHC beam dump blocks. Collimators and beam absorbers are also of the interest for other labs and accelerators: - CERN: for the CNGS target, for SPS beam absorbers (extraction protection) and collimators for protecting the transfer line between SPS an...

PHOTOIONIZATION OF HIGH-ALTITUDE GAS IN A SUPERNOVA-DRIVEN TURBULENT INTERSTELLAR MEDIUM

International Nuclear Information System (INIS)

Wood, Kenneth; Hill, Alex S.; Haffner, L. Matthew; Reynolds, R. J.; Joung, M. Ryan; Mac Low, Mordecai-Mark; Benjamin, Robert A.; Madsen, G. J.

2010-01-01

We investigate models for the photoionization of the widespread diffuse ionized gas (DIG) in galaxies. In particular, we address the long standing question of the penetration of Lyman continuum photons from sources close to the galactic midplane to large heights in the galactic halo. We find that recent hydrodynamical simulations of a supernova-driven interstellar medium (ISM) have low-density paths and voids that allow for ionizing photons from midplane OB stars to reach and ionize gas many kiloparsecs above the midplane. We find that ionizing fluxes throughout our simulation grids are larger than predicted by one-dimensional slab models, thus allowing for photoionization by O stars of low altitude neutral clouds in the Galaxy that are also detected in Hα. In previous studies of such clouds, the photoionization scenario had been rejected and the Hα had been attributed to enhanced cosmic ray ionization or scattered light from midplane H II regions. We do find that the emission measure distributions in our simulations are wider than those derived from Hα observations in the Milky Way. In addition, the horizontally averaged height dependence of the gas density in the hydrodynamical models is lower than inferred in the Galaxy. These discrepancies are likely due to the absence of magnetic fields in the hydrodynamic simulations and we discuss how magnetohydrodynamic effects may reconcile models and observations. Nevertheless, we anticipate that the inclusion of magnetic fields in the dynamical simulations will not alter our primary finding that midplane OB stars are capable of producing high-altitude DIG in a realistic three-dimensional ISM.

Gamma-ray energy absorption in absorbing homogeneous medium. Applications to Oceanography and Geophysics (Gamma-ray spectroscopy from 500 to 1500 keV)

International Nuclear Information System (INIS)

Lapicque, G.

1980-01-01

The aim of this study is to establish a general algebrical approach for the calculation, without any program, of the full energy peak efficiency of a detecting probe designed to measure the gamma activity of a radio-element in a (semi) infinite homogeneous absorbing medium such as the Sea. The radio-active source may be punctual or, most often, constitute an integral part of the medium. The proposed theory is valid for any purely absorptive process of particles moving along straight trajectories, diffusion effects being allowed for separately. The formulation assumes a spherical detector and calculations are made for models having the same volume as two standard phosphors (10 cm x8 cm and 5 cm x 4.5 cm) in the energy band 0.5 to 1.5 MeV. The parameters are the detector radius and, at energy E 0 , the absorption coefficients in the various media for gamma rays together with the 'peak/total' ratio in the detector. The fact that this latter factor, which varies with each trajectory, cannot be obtained with accuracy, constitutes the main limitation of the formulation. The comparison with experimental results obtained with a 10 cm x 8 cm phosphor at the C.F.R. (Centre des Faibles Radioactivites, Gif-sur-Yvette) and with various data indicates an error of about +-5% for a point source at contact and -30% for a homogeneously distributed source in an infinite medium. This latter value may be interpreted as a superiority of the spherical shape over the cylinder (used in practice), for detectors operating in infinite media. Calculations are made without allowing for the Compton effect, which is found to give an approximate correction of +5% in water for a band width of 10 keV in the MeV region. Finally, the shape of the detecting probe around the detector is shown to be indifferent in the assumption of a constant peak/total ratio [fr

Optimum performance characteristics of a solar-driven Stirling heat engine system

International Nuclear Information System (INIS)

Liao, Tianjun; Lin, Jian

2015-01-01

Graphical abstract: T–S diagram of the SHE cycle. - Highlights: • Based on Lagrange multiplier method, the optimal performance are investigated. • The energy balance between the absorber and the hot side of Stirling heat engine is considered. • The effects of major parameters on the optimal performance are investigated. - Abstract: A solar-driven Stirling heat engine system composed of a Stirling heat engine, a solar collector, and a heat sink is presented, in which the radiation and convection heat losses of the solar collector, the heat-leak between the thermal absorber and heat sink, the regenerative losses of the Stirling heat engine, and the energy balance between the thermal absorber and the high isothermal process of the Stirling heat engine are taken into consideration. Based on the irreversible thermodynamics and Lagrange multiplier method, the maximum power output and the corresponding optimal efficiency of the system are determined and the absorber temperature that maximizes the optimal system efficiency is calculated numerically. The influences of some system parameters such as the concentrating ratio, the volume ratio during the regenerative processes and irreversibilities of heat exchange processes on the optimal efficiency are analyzed in details. The results obtained here may provide a new idea to design practical solar-driven Stirling heat engine system

Shock absorber

International Nuclear Information System (INIS)

Housman, J.J.

1978-01-01

A shock absorber is described for use in a hostile environment at the end of a blind passage for absorbing impact loads. The shock absorber includes at least one element which occupies the passage and which is comprised of a porous brittle material which is substantially non-degradable in the hostile environment. A void volume is provided in the element to enable the element to absorb a predetermined level of energy upon being crushed due to impact loading

The Pneumatic Actuators As Vertical Dynamic Load Simulators On Medium Weighted Wheel Suspension Mechanism

Science.gov (United States)

Ka'ka, Simon; Himran, Syukri; Renreng, Ilyas; Sutresman, Onny

2018-02-01

Almost all of road damage can be caused by dynamic loads of vehicles that fluctuate according to the type of vehicle that passes through. This study aims to calculate the vertical dynamic load of the vehicle actually occurs on road construction by the mechanism of vehicle wheel suspension. Pneumatic cylinders driven by pressurized air directly load the spring and shock absorber installed on the wheels of the vehicle. The load fluctuations of the medium weight categorized vehicles are determined by the regulation of the amount of pressurized air that enters into the pneumatic cylinder chamber, pushing the piston and connecting rods. The displacement that occurs during compression on the spring and shock absorber, is substituted into the equation of vehicle dynamic load while taking into account the spring stiffness constant, and the fluid or damper gas coefficient. The results show that the magnitude of the displacement when the compression force works has significant influences to the amount of vertical dynamic load of the vehicle that overlies the road construction. The presence of dynamic load of vehicles that fluctuates and repeats, also affects on the reduction of road ability to receive the load. Experimental results using pneumatic actuators instead of real dynamic vehicle loads illustrate the characteristics of the relationship between work pressure and dynamic load. If the working pressure of P2 (bar) is greater, the vertical dynamic load Ft (N) that overloads the road structure is also greater. The associate graphs show that the shock absorber has a greater ability to reduce dynamic load vertically that burden the road structure when compared with the ability of screw spring.

Optimization on microwave absorbing properties of carbon nanotubes and magnetic oxide composite materials

Science.gov (United States)

Mingdong, Chen; Huangzhong, Yu; Xiaohua, Jie; Yigang, Lu

2018-03-01

Based on the physical principle of interaction between electromagnetic field and the electromagnetic medium, the relationship between microwave absorbing coefficient (MAC) and the electromagnetic parameters of materials was established. With the composite materials of nickel ferrite (NiFe2O4), carbon nanotubes (CNTs) and paraffin as an example, optimization on absorbing properties of CNTs/magnetic oxide composite materials was studied at the frequency range of 2-18 GHz, and a conclusion is drawn that the MAC is the biggest at the same frequency, when the CNTs is 10 wt% in the composite materials. Through study on the relationship between complex permeability and MAC, another interesting conclusion is drawn that MAC is obviously affected by the real part of complex permeability, and increasing real part of complex permeability is beneficial for improving absorbing properties. The conclusion of this paper can provide a useful reference for the optimization research on the microwave absorbing properties of CNTs/ferrite composite materials.

Shock absorbing structure

International Nuclear Information System (INIS)

Kojima, Naoki; Matsushita, Kazuo.

1992-01-01

Small pieces of shock absorbers are filled in a space of a shock absorbing vessel which is divided into a plurality of sections by partitioning members. These sections function to prevent excess deformation or replacement of the fillers upon occurrence of falling accident. Since the shock absorbing small pieces in the shock absorbing vessel are filled irregularly, shock absorbing characteristics such as compression strength is not varied depending on the direction, but they exhibit excellent shock absorbing performance. They surely absorb shocks exerted on a transportation vessel upon falling or the like. If existing artificial fillers such as pole rings made of metal or ceramic and cut pieces such as alumium extrusion molding products are used as the shock absorbing pieces, they have excellent fire-proofness and cold resistance since the small pieces are inflammable and do not contain water. (T.M.)

EM wave propagation analysis in plasma covered radar absorbing material

CERN Document Server

Singh, Hema; Rawat, Harish Singh

2017-01-01

This book focuses on EM propagation characteristics within multilayered plasma-dielectric-metallic media. The method used for analysis is impedance transformation method. Plasma covered radar absorbing material is approximated as a multi-layered dielectric medium. The plasma is considered to be bounded homogeneous/inhomogeneous medium. The reflection coefficient and hence return loss is analytically derived. The role of plasma parameters, such as electron density, collision frequency, plasma thickness, and plasma density profile in the absorption behavior of multi-layered plasma-RAM structure is described. This book provides a clearer picture of EM propagation within plasma. The reader will get an insight of plasma parameters that play significant role in deciding the absorption characteristics of plasma covered surfaces.

WARM GAS IN THE VIRGO CLUSTER. I. DISTRIBUTION OF Lyα ABSORBERS

International Nuclear Information System (INIS)

Yoon, Joo Heon; Putman, Mary E.; Bryan, Greg L.; Thom, Christopher; Chen, Hsiao-Wen

2012-01-01

The first systematic study of the warm gas (T = 10 4–5 K) distribution across a galaxy cluster is presented using multiple background QSOs in and around the Virgo Cluster. We detect 25 Lyα absorbers (N HI = 10 13.1–15.4 cm –2 ) in the Virgo velocity range toward 9 of 12 QSO sightlines observed with the Cosmic Origin Spectrograph, with a cluster impact parameter range of 0.36-1.65 Mpc (0.23-1.05 R vir ). Including 18 Lyα absorbers previously detected by STIS or GHRS toward 7 of 11 background QSOs in and around the Virgo Cluster, we establish a sample of 43 absorbers toward a total of 23 background probes for studying the incidence of Lyα absorbers in and around the Virgo Cluster. With these absorbers, we find (1) warm gas is predominantly in the outskirts of the cluster and avoids the X-ray-detected hot intracluster medium (ICM). Also, Lyα absorption strength increases with cluster impact parameter. (2) Lyα-absorbing warm gas traces cold H I-emitting gas in the substructures of the Virgo Cluster. (3) Including the absorbers associated with the surrounding substructures, the warm gas covering fraction (100% for N HI > 10 13.1 cm –2 ) is in agreement with cosmological simulations. We speculate that the observed warm gas is part of large-scale gas flows feeding the cluster both in the ICM and galaxies.

Multimodal tuned dynamic absorber for split Stirling linear cryocooler

Science.gov (United States)

Veprik, A.; Tuito, A.

2017-02-01

Forthcoming low size, weight, power and price split Stirling linear cryocoolers may rely on electro-dynamically driven single-piston compressors and pneumatically driven expanders interconnected by the configurable transfer line. For compactness, compressor and expander units may be placed in a side-by-side manner, thus producing tonal vibration export comprising force and moment components. In vibration sensitive applications, this may result in excessive angular line of sight jitter and translational defocusing affecting the image quality. The authors present Multimodal Tuned Dynamic Absorber (MTDA), having one translational and two tilting modes essentially tuned to the driving frequency. The dynamic reactions (force and moment) produced by such a MTDA are simultaneously counterbalancing force and moment vibration export produced by the cryocooler. The authors reveal the design details, the method of fine modal tuning and outcomes of numerical simulation on attainable performance.

Pneumatic Adaptive Absorber: Mathematical Modelling with Experimental Verification

Directory of Open Access Journals (Sweden)

Grzegorz Mikułowski

2016-01-01

Full Text Available Many of mechanical energy absorbers utilized in engineering structures are hydraulic dampers, since they are simple and highly efficient and have favourable volume to load capacity ratio. However, there exist fields of applications where a threat of toxic contamination with the hydraulic fluid contents must be avoided, for example, food or pharmacy industries. A solution here can be a Pneumatic Adaptive Absorber (PAA, which is characterized by a high dissipation efficiency and an inactive medium. In order to properly analyse the characteristics of a PAA, an adequate mathematical model is required. This paper proposes a concept for mathematical modelling of a PAA with experimental verification. The PAA is considered as a piston-cylinder device with a controllable valve incorporated inside the piston. The objective of this paper is to describe a thermodynamic model of a double chamber cylinder with gas migration between the inner volumes of the device. The specific situation considered here is that the process cannot be defined as polytropic, characterized by constant in time thermodynamic coefficients. Instead, the coefficients of the proposed model are updated during the analysis. The results of the experimental research reveal that the proposed mathematical model is able to accurately reflect the physical behaviour of the fabricated demonstrator of the shock absorber.

Absorbing Property of Multi-layered Short Carbon Fiber Absorbing Coating

OpenAIRE

Liu, Zhaohui; Tao, Rui; Ban, Guodong; Luo, Ping

2018-01-01

The radar absorbing coating was prepared with short carbon fiber asabsorbent and waterborne polyurethane (WPU) as matrix resin. The coating’s absorbing property was tested with vectornetwork analyzer, using aramid honeycomb as air layer which was matched withcarbon fiber coating. The results demonstrate that the single-layered carbonfiber absorbing coating presented relatively poor absorbing property when thelayer was thin, and the performance was slightly improved after the matched airlayer ...

A Q-Switched Erbium-Doped Fiber Laser with a Carbon Nanotube Based Saturable Absorber

International Nuclear Information System (INIS)

Harun, S. W.; Ismail, M. A.; Ahmad, F.; Ismail, M. F.; Nor, R. M.; Zulkepely, N. R.; Ahmad, H.

2012-01-01

We demonstrate a simple, compact and low cost Q-switched erbium-doped fiber laser (EDFL) using single-wall carbon nanotubes (CNTs) as a saturable absorber for possible applications in metrology, sensing, and medical diagnostics. The EDFL operates at around 1560 nm with repetition rates of 16.1 kHz and 6.4 kHz with saturable absorbers SA1 and SA2 at a pump power of 120 mW. The absorbers are constructed by optically driven deposition and normal deposition techniques. It is observed that the optical deposition method produces a Q-switched EDFL with a lower threshold of 70 mW and better Q-switching performance compared to that of the normal deposition method. The EDFL also has pulse energy of 90.3 nJ and pulse width of 11.6 μs at 120 mW pump power

Decay of correlations between cross-polarized electromagnetic waves in a two-dimensional random medium.

Science.gov (United States)

Gorodnichev, E E

2018-04-01

The problem of multiple scattering of polarized light in a two-dimensional medium composed of fiberlike inhomogeneities is studied. The attenuation lengths for the density matrix elements are calculated. For a highly absorbing medium it is found that, as the sample thickness increases, the intensity of waves polarized along the fibers decays faster than the other density matrix elements. With further increase in the sample thickness, the off-diagonal elements which are responsible for correlations between the cross-polarized waves disappear. In the asymptotic limit of very thick samples the scattered light proves to be polarized perpendicular to the fibers. The difference in the attenuation lengths between the density matrix elements results in a nonmonotonic depth dependence of the degree of polarization. In the opposite case of a weakly absorbing medium, the off-diagonal element of the density matrix and, correspondingly, the correlations between the cross-polarized fields are shown to decay faster than the intensity of waves polarized along and perpendicular to the fibers.

A POPULATION OF WEAK METAL-LINE ABSORBERS SURROUNDING THE MILKY WAY

International Nuclear Information System (INIS)

Richter, Philipp; Charlton, Jane C.; Fangano, Alessio P. M.; Bekhti, Nadya Ben; Masiero, Joseph R.

2009-01-01

We report on the detection of a population of weak metal-line absorbers in the halo or nearby intergalactic environment of the Milky Way. Using high-resolution ultraviolet absorption-line spectra of bright quasars (QSO) obtained with the Space Telescope Imaging Spectrograph (STIS), along six sight lines we have observed unsaturated, narrow absorption in O I and Si II, together with mildly saturated C II absorption at high radial velocities (|v LSR | = 100-320 km s -1 ). The measured O I column densities lie in the range N(O I) 14 cm -2 implying that these structures represent Lyman limit Systems and sub-Lyman limit System with H I column densities between 10 16 and 3 x 10 18 cm -2 , thus below the detection limits of current 21 cm all-sky surveys of high-velocity clouds (HVCs). The absorbers apparently are not directly associated with any of the large high column density HVC complexes, but rather represent isolated, partly neutral gas clumps embedded in a more tenuous, ionized gaseous medium situated in the halo or nearby intergalactic environment of the Galaxy. Photoionization modeling of the observed low ion ratios suggests typical hydrogen volume densities of n H > 0.02 cm -3 and characteristic thicknesses of a several parsec down to subparsec scales. For three absorbers, metallicities are constrained in the range of 0.1-1.0 solar, implying that these gaseous structures may have multiple origins inside and outside the Milky Way. Using supplementary optical absorption-line data, we find for two other absorbers Ca II/O I column-density ratios that correspond to solar Ca/O abundance ratios. This finding indicates that these clouds do not contain significant amounts of dust. This population of low column density gas clumps in the circumgalactic environment of the Milky Way is indicative of the various processes that contribute to the circulation of neutral gas in the extended halos of spiral galaxies. These processes include the accretion of gas from the

Time evolution of tunneling in a thermal medium: Environment-driven excited tunneling

International Nuclear Information System (INIS)

Matsumoto, Sh.; Yoshimura, M.

2004-01-01

Time evolution of tunneling phenomena proceeding in a thermal medium is studied using a standard model of environmental interaction. A semiclassical probability formula for the particle motion in a metastable state of a one-dimensional system put in a thermal medium is combined with the formula of the quantum penetration factor through a potential barrier to derive the tunneling rate in the medium. The effect of environment, its influence on time evolution in particular, is clarified in our real-time formalism. A nonlinear resonance effect is shown to enhance the tunneling rate at finite times of order 2/η, with η the friction coefficient unless η is too small. In the linear approximation this effect has relevance to the parametric resonance. This effect enhances the possibility of early termination of the cosmological phase transition much prior to the typical Hubble time

Method of absorbing UF6 from gaseous mixtures in alkamine absorbents

International Nuclear Information System (INIS)

Lafferty, R.H.; Smiley, S.H.; Radimer, K.J.

1976-01-01

A method is described for recovering UF 6 from gaseous mixtures by absorption in a liquid. The liquid absorbent must have a relatively low viscosity and at least one component of the absorbent is an alkamine having less than 3 carbon atoms bonded to the amino nitrogen, less than 2 of the carbon atoms other than those bonded to the amino nitrogen are free of the hydroxy radical and precipitate the absorbed uranium from the absorbent. At least one component of the absorbent is chosen from the group consisting of ethanolamine, diethanolamine, and 3-methyl-3-amino-propane-diol-1,2

Business Model Innovation for Small Medium Enterprises

OpenAIRE

Wirania Swasty

2015-01-01

Indonesian economy through Small Medium Enterprises (SMEs) is expected to absorb labor and contribute to the growth of Gross Domestic Product. However, SMEs lack both managerial and technical skills. This research is about business model innovation for SMEs especially in fashion and garment industry. Study used qualitative approach by mentoring four selected SMEs in Babakan Penghulu Village– Cinambo Sub-District, Eastern Bandung. The tools used to analyze them including PEST analysis, Porter’...

An online, energy-resolving beam profile detector for laser-driven proton beams

Energy Technology Data Exchange (ETDEWEB)

Metzkes, J.; Rehwald, M.; Obst, L.; Schramm, U. [Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Technische Universität Dresden, 01062 Dresden (Germany); Zeil, K.; Kraft, S. D.; Sobiella, M.; Schlenvoigt, H.-P. [Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Karsch, L. [OncoRay-National Center for Radiation Research in Oncology, Technische Universität Dresden, 01307 Dresden (Germany)

2016-08-15

In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ∼4 mm and the detector can resolve proton beam profiles for up to 9 proton threshold energies. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energy can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source, as well as the first detector application at a laser-driven proton source.

The Time Structure of Hadronic Showers in Highly Granular Calorimeters with Tungsten and Steel Absorbers

CERN Document Server

Adloff, C.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S.T.; Sosebee, M.; White, A.P.; Yu, J.; Eigen, G.; Thomson, M.A.; Ward, D.R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Arfaoui, A.; Benoit, M.; Dannheim, D.; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Roloff, P.; Sailer, A.; Schlatter, D.; Sicking, E.; Strube, J.; Uzhinskiy, V.; Carloganu, C.; Gay, P.; Manen, S.; Royer, L.; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Fagot, A.; Tytgat, M.; Zaganidis, N.; Hostachy, J.-Y.; Morin, L.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch.; Shen, W.; Stamen, R.; Chang, S.; Khan, A.; Kim, D.H.; Kong, D.J.; Oh, Y.D.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G.W.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Ueno, H.; Yoshioka, T.; Dauncey, P.D.; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Ete, R.; Grenier, G.; Han, R.; Ianigro, J-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kozlov, V.; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Popova, E.; Tikhomirov, V.; Gabriel, M.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M.S.; Bonis, J.; Conforti di Lorenzo, S.; Cornebise, P.; Fleury, J.; Frisson, T.; van der Kolk, N.; Richard, F.; Pöschl, R.; Rouene, J.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Ruan, M.; Tran, T.H.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; de la Taille, Ch.; Raux, L.; Seguin-Moreau, N.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Ono, H.; Takeshita, T.; Uozumi, S.; Chai, J.S.; Song, H.S.; Lee, S.H.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

2014-01-01

The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

Emittance of a finite scattering medium with refractive index greater than unity

International Nuclear Information System (INIS)

Crosbie, A.L.

1980-01-01

Refractive index and scattering can significantly influence the transfer of radiation in a semitransparent medium such as water, glass, plastics, or ceramics. In a recent article (1979), the author presented exact numerical results for the emittance of a semiinfinite scattering medium with a refractive index greater than unity. The present investigation extends the analysis to a finite medium. The physical situation consists of a finite planar layer. The isothermal layer emits, absorbs, and isotropically scatters thermal radiation. It is characterized by single scattering albedo, optical thickness, refractive index, and temperature. A formula for the directional emittance is derived, the directional emittance being the emittance of the medium multiplied by the interface transmittance. The ratio of hemispherical to normal emittance is tabulated and discussed

Density ratios in compressions driven by radiation pressure

International Nuclear Information System (INIS)

Lee, S.

1988-01-01

It has been suggested that in the cannonball scheme of laser compression the pellet may be considered to be compressed by the 'brute force' of the radiation pressure. For such a radiation-driven compression, an energy balance method is applied to give an equation fixing the radius compression ratio K which is a key parameter for such intense compressions. A shock model is used to yield specific results. For a square-pulse driving power compressing a spherical pellet with a specific heat ratio of 5/3, a density compression ratio Γ of 27 is computed. Double (stepped) pulsing with linearly rising power enhances Γ to 1750. The value of Γ is not dependent on the absolute magnitude of the piston power, as long as this is large enough. Further enhancement of compression by multiple (stepped) pulsing becomes obvious. The enhanced compression increases the energy gain factor G for a 100 μm DT pellet driven by radiation power of 10 16 W from 6 for a square pulse power with 0.5 MJ absorbed energy to 90 for a double (stepped) linearly rising pulse with absorbed energy of 0.4 MJ assuming perfect coupling efficiency. (author)

Is the intercloud medium pervasive

International Nuclear Information System (INIS)

Heiles, C.

1980-01-01

We consider the pervasiveness of the ''not strongly absorbing'' (NSA) H I gas, which is the intercloud medium in steady state theories of the interstellar medium. We study the question by analyzing wide emission components in nearby gas, and the absence of absorption components in distant gas. We conclude that the NSA material is deficient in the immediately local solar vicinity. In nearby regions it contains 38% of the interstellar H I; it is generally pervasive and often has internal motions which greatly increase its velocity dispersion above the 5 km s -1 minimum value. It contains large holes, perhaps ranging up to 400 pc diameter, which probably occupy 10--20% of the volume. In distant regions the NSA material seems to be pervasive outside 8 kpc galactic radius. For galactic radii between 8 and 10 kpc its thickness agrees with previous determinations of 370 pc for nearby regions. Outside 10 kpc the thickness increases dramatically. Inside 8 kpc there are no data

Quasars Probing Quasars: the Circumgalactic Medium Surrounding z ~ 2 Quasars

Science.gov (United States)

Lau, Marie; Quasars Probing Quasars survey

2018-01-01

Understanding the circumgalactic medium--the gaseous halo surrounding a galaxy, is an integral part to understanding galaxy evolution. The z ~ 2-3 universe is interesting as this is when the star formation rate and AGN activity peak. My thesis concludes the decade-long Quasars Probing Quasars survey designed for studying massive galaxy formation and quasar feedback. I use background quasar sightlines that pass close to foreground quasars to study the circumgalactic medium of quasar-host galaxies in absorption. My sample of 149 quasar pairs involve spectra taken with 17 different optical and near IR instruments. I present results on the statistical and physical properties of the circumgalactic medium. The circumgalactic medium is enriched even beyond the virial radius. The alpha/Fe abundance ratio is enhanced, suggesting enrichment from core-collapse supernovae. The cool gas mass within the virial radius is enough to fuel star formation for another Gyr, and may account for 1/3 of the baryonic budget of the galaxy halo. The ionization state increases with projected distance from the quasar, which implies the quasar does not dominate the ionizing radiation flux. However, detection of fluorescent Lyman-alpha emission and NV absorption imply these transverse absorbers are partially illuminated by the quasar. In one peculiar case, the absorbing clump has density >100 cm^-3 and sub-parsec size. The average absorption in the circumgalactic medium exhibits large velocity widths, and is asymmetric about the systemic redshift of the galaxies. The widths are consistent with gravitational motions and Hubble flow, and outflows are not required to explain them. The asymmetry can be explained if the ionizing radiation from the quasar is anisotropic or intermittent and the gas is not in inflow. My results pose challenges for cosmological hydrodynamic simulations to produce a substantial cool gas reservoir surrounding quasars, that is also enriched and shows extreme kinematics.

Frequency-dependent absorbance of broadband terahertz wave in dense plasma sheet

Science.gov (United States)

Peng, Yan; Qi, Binbin; Jiang, Xiankai; Zhu, Zhi; Zhao, Hongwei; Zhu, Yiming

2018-05-01

Due to the ability of accurate fingerprinting and low-ionization for different substances, terahertz (THz) technology has a lot of crucial applications in material analysis, information transfer, and safety inspection, etc. However, the spectral characteristic of atmospheric gas and ionized gas has not been widely investigated, which is important for the remote sensing application. Here, in this paper, we investigate the absorbance of broadband terahertz wave in dense plasma sheet generated by femtosecond laser pulses. It was found that as the terahertz wave transmits through the plasma sheet formed, respectively, in carbon dioxide, oxygen, argon and nitrogen, spectrum presents completely different and frequency-dependent absorbance. The reasons for these absorption peaks are related to the molecular polarity, electric charge, intermolecular and intramolecular interactions, and collisional absorption of gas molecules. These results have significant implications for the remote sensing of gas medium.

Absorber and regenerator models for liquid desiccant air conditioning systems. Validation and comparison using experimental data

Energy Technology Data Exchange (ETDEWEB)

Krause, M.; Heinzen, R.; Jordan, U.; Vajen, K. [Kassel Univ., Inst. of Thermal Engineering, Kassel (Germany); Saman, W.; Halawa, E. [Sustainable Energy Centre, Univ. of South Australia, Mawson Lakes, Adelaide (Australia)

2008-07-01

Solar assisted air conditioning systems using liquid desiccants represent a promising option to decrease high summer energy demand caused by electrically driven vapor compression machines. The main components of liquid desiccant systems are absorbers for dehumidifying and cooling of supply air and regenerators for concentrating the desiccant. However, high efficient and validated reliable components are required and the design and operation have to be adjusted to each respective building design, location, and user demand. Simulation tools can help to optimize component and system design. The present paper presents new developed numerical models for absorbers and regenerators, as well as experimental data of a regenerator prototype. The models have been compared with a finite-difference method model as well as experimental data. The data are gained from the regenerator prototype presented and an absorber presented in the literature. (orig.)

Aperiodic-metamaterial-based absorber

Directory of Open Access Journals (Sweden)

Quanlong Yang

2017-09-01

Full Text Available The periodic-metamaterial-based perfect absorber has been studied broadly. Conversely, if the unit cell in the metamaterial-based absorber is arranged aperiodically (aperiodic-metamaterial-based absorber, how does it perform? Inspired by this, here we present a systematic study of the aperiodic-metamaterial-based absorber. By investigating the response of metamaterial absorbers based on periodic, Fibonacci, Thue-Morse, and quasicrystal lattices, we found that aperiodic-metamaterial-based absorbers could display similar absorption behaviors as the periodic one in one hand. However, their absorption behaviors show different tendency depending on the thicknesses of the spacer. Further studies on the angle and polarization dependence of the absorption behavior are also presented.

Floquet prethermalization and regimes of heating in a periodically driven, interacting quantum system

Science.gov (United States)

Weidinger, Simon; Knap, Michael

We study the regimes of heating in the periodically driven O (N) -model, which represents a generic model for interacting quantum many-body systems. By computing the absorbed energy with a non-equilibrium Keldysh Green's function approach, we establish three dynamical regimes: at short times a single-particle dominated regime, at intermediate times a stable Floquet prethermal regime in which the system ceases to absorb, and at parametrically late times a thermalizing regime. Our simulations suggest that in the thermalizing regime the absorbed energy grows algebraically in time with an the exponent that approaches the universal value of 1 / 2 , and is thus significantly slower than linear Joule heating. Our results demonstrate the parametric stability of prethermal states in a generic many-body system driven at frequencies that are comparable to its microscopic scales. This paves the way for realizing exotic quantum phases, such as time crystals or interacting topological phases, in the prethermal regime of interacting Floquet systems. We acknowledge support from the Technical University of Munich - Institute for Advanced Study, funded by the German Excellence Initiative and the European Union FP7 under Grant agreement 291763, and from the DFG Grant No. KN 1254/1-1.

Absorbing rods for nuclear fast neutron reactor absorbing assembly

International Nuclear Information System (INIS)

Aji, M.; Ballagny, A.; Haze, R.

1986-01-01

The invention proposes a neutron absorber rod for neutron absorber assembly of a fast neutron reactor. The assembly comprises a bundle of vertical rods, each one comprising a stack of pellets made of a neutron absorber material contained in a long metallic casing with a certain radial play with regard to this casing; this casing includes traps for splinters from the pellets which may appear during reactor operation, at the level of contact between adjacent pellets. The present invention prevents the casing from rupture involved by the disintegration of the pellets producing pieces of boron carbide of high hardness [fr

Methods for absorbing neutrons

Science.gov (United States)

Guillen, Donna P [Idaho Falls, ID; Longhurst, Glen R [Idaho Falls, ID; Porter, Douglas L [Idaho Falls, ID; Parry, James R [Idaho Falls, ID

2012-07-24

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

The difference in backscatter factors of diagnostic X-rays by the difference in the scattering medium and in the objective dose

International Nuclear Information System (INIS)

Kato, Hideki; Sakai, Keita; Uchiyama, Mizuki; Suzuki, Kentaro

2016-01-01

The diagnostic reference levels (DRLs) of the general X-ray radiography are defined by the absorbed dose of air at the entrance surface with backscattered radiation from a scattering medium. Generally, the entrance surface dose of the general X-ray radiography is calculated from measured air kerma of primary X-ray multiplied by a backscatter factor (BSF). However, the BSF data employed at present used water for scattering medium, and was calculated based on the water-absorbed dose by incident primary photons and backscattered photons from the scattering medium. In the calculation of air dose at the entrance surface defined in DRLs, there are no theoretical consistencies for using BSF based on water dose, and this may be a cause of calculation error. In this paper, we verified the difference in BSF by the difference in the scattering medium and by the difference in the objective dose by means of the Monte Carlo simulation. In this calculation, the scattering medium was set as water and the soft-tissue, and the objective dose was set as air dose, water dose, soft-tissue dose, and skin dose. The difference in BSF calculated by the respective combination was at most about 1.3% and was less than 1% in most cases. In conclusion, even if the entrance surface dose defined by DRLs of general X-ray radiography is calculated using BSF, which set both the scattering medium and the object substance of the absorbed dose as water, a so big error doesn't show. (author)

Influence of absorption on the time of flight of the light going through a complex medium

Directory of Open Access Journals (Sweden)

M. Kervella

2011-09-01

Full Text Available The aim of this work is to evaluate the influence of absorption processes on the time of flight of light going through an absorbing and scattering thick medium (clouds, paints, gas cell, etc. In order to study statistical scattering and absorbing processes, we use a Monte-Carlo simulation code with temporal phase function and Debye modes. The main result is that absorption inside particles induces a decrease of the global time delay.

Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

Energy Technology Data Exchange (ETDEWEB)

Cheng, Yang; Xu, Yonggang, E-mail: xuyonggang221@163.com; Cai, Jun; Yuan, Liming; Zhang, Deyuan

2015-09-01

Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1–4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches −7.8 dB), and as the RL was less than −10 dB the absorption band was widest (2.1–3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band. - Graphical abstract: Morphology of composites filled with flaky CIPs and the bio-absorbent. The enhancement of bio-absorbent on the electromagnetic absorption property of composites filled with flaky carbonyl iron particles (CIPs) is attributed to the interaction of the two absorbents. The volume content of the FCMPs with the larger shape CIPs play an important role in this effects, the composites filled with irons and bio-absorbents can achieve wider-band and thinner-thickness absorbing materials. - Highlights: • Absorbers filled with bio-absorbents and CIPs was fabricated. • Bio-absorbents enhanced the permittivity and permeability of the composites. • The absorbent interactions play a key role in the enhancement mechanism. • Bio-absorbents enhanced the composite RL in 1–4 GHz.

Development of Zinc Tin Nitride for Application as an Earth Abundant Photovoltaic Absorber

Science.gov (United States)

Fioretti, Angela N.

In recent years, many new potential absorber materials based on earth-abundant and non-toxic elements have been predicted. These materials, often made in thin film form and known to absorb light 10-1000 times more e ciently than crystalline silicon, could lower module cost and enable broader solar deployment. One such material is zinc tin nitride (ZnSnN 2), a II-IV-nitride analog of the III-nitride materials, which was identified as a suitable solar absorber due to its direct bandgap, large absorption coefficient, and disorder-driven bandgap tunability. Despite these desirable properties, initial attempts at synthesis resulted in degenerate n-type carrier density. Computational work on the point defect formation energies for this material revealed three donor defects were likely the cause; specifically SnZn antisites, VN sites, and ON substitutions. Given this framework, a defect-driven hypothesis was proposed as a starting point for the present work: if each donor defect could be addressed by tuning deposition parameters, n-type degeneracy may be defeated. By using combinatorial co- sputtering to grow compositionally-graded thin film samples, n-type carrier density was reduced by two orders of magnitude compared to state-of-the-art. This reduction in carrier density was observed for zinc-rich samples, which supported the defect-driven hypothesis initially proposed. These results and their implications are the topic of Chapter 2. Further carrier density control in zinc-rich ZTN was achieved via hydrogen incorporation and post-growth annealing. This strategy was hypothesized to operate by passivating acceptor defects to avoid self-compensation, which were then activated by hydrogen drive- out upon annealing. Carrier density was reduced another order of magnitude using this technique, which is presented in Chapter 3. After defeating n-type degeneracy, a deeper understanding of the electronic structure was pursued. Photoluminescence (PL) was used to study electronic

[Absorbable coronary stents. New promising technology].

Science.gov (United States)

Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

2007-06-01

Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal. The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated. Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion

Absorbant materials

International Nuclear Information System (INIS)

Quetier, Monique.

1978-11-01

Absorbants play a very important part in the nuclear industry. They serve for the control, shut-down and neutron shielding of reactors and increase the capacity of spent fuel storage pools and of special transport containers. This paper surveys the usual absorbant materials, means of obtainment, their essential characteristics relating to their use and their behaviour under neutron irradiation [fr

Generator-absorber-heat exchange heat transfer apparatus and method and use thereof in a heat pump

Science.gov (United States)

Phillips, B.A.; Zawacki, T.S.

1998-07-21

Numerous embodiments and related methods for generator-absorber heat exchange (GAX) are disclosed, particularly for absorption heat pump systems. Such embodiments and related methods use, as the heat transfer medium, the working fluid of the absorption system taken from the generator at a location where the working fluid has a rich liquor concentration. 5 figs.

Absorbed dose optimization in the microplanar beam radiotherapy

International Nuclear Information System (INIS)

Company, F.Z.; Jaric, J.; Allen, B.J.

1996-01-01

Full text: Recent advances in synchrotron generated X-ray beams with high fluence rate, small divergence and sharply defined microbeam margins permit investigation of the application of an array of closely spaced, parallel or converging microbeams for radiotherapy. The proposed technique takes advantage of the repair mechanism hypothesis of capillary endothelial cells between alternate microbeam zones, which regenerates the lethally irradiated capillaries. Unlike a pencil beam, more accurate dose calculation, beam width and spacing are essential to minimise radiation damage to normal tissue cells outside the target. The absorbed dose between microbeam zones should be kept below the threshold for irreversible radiation damage. Thus the peak-to-valley ratio for the dose distribution should be optimized. The absorbed dose profile depends on the energy of the incident beam and the composition and density of the medium. Using Monte Carlo computations, the radial absorbed dose of single 24 x 24 μm 2 cross-section X-ray beams of different energies in a tissue/lung/tissue phantom was investigated. The results indicated that at 100 keV, closely spaced square cross-sectional microbeams can be applied to the lung. A bundle of parallel 24 μm-wide planar microbeams spaced at 200 μm intervals provides much more irradiation coverage of tissue than is provided by a bundle of parallel, square cross-sectional microbeam, although the former is associated with much smaller Peak (maximum absorbed dose on the beam axis) -to-Valley ( minimum interbeam absorbed dose ) ratios than the latter. In this study the lateral and depth dose of single and multiple microplanar beams with beam dimensions of width 24 μm and 48 μm and height 2-20 cm with energy of 100 keV in a tissue/lung/tissue phantom are investigated. The EGS4 Monte Carlo code is used to calculate dose profiles at different depths and bundles of beams (2 x 2 cm 2 to 20 x 20 cm 2 square cross section) with a 150 μm 200 μm and

Diffusion Driven Combustion Waves in Porous Media

Science.gov (United States)

Aldushin, A. P.; Matkowsky, B. J.

2000-01-01

Filtration of gas containing oxidizer, to the reaction zone in a porous medium, due, e.g., to a buoyancy force or to an external pressure gradient, leads to the propagation of Filtration combustion (FC) waves. The exothermic reaction occurs between the fuel component of the solid matrix and the oxidizer. In this paper, we analyze the ability of a reaction wave to propagate in a porous medium without the aid of filtration. We find that one possible mechanism of propagation is that the wave is driven by diffusion of oxidizer from the environment. The solution of the combustion problem describing diffusion driven waves is similar to the solution of the Stefan problem describing the propagation of phase transition waves, in that the temperature on the interface between the burned and unburned regions is constant, the combustion wave is described by a similarity solution which is a function of the similarity variable x/square root of(t) and the wave velocity decays as 1/square root of(t). The difference between the two problems is that in the combustion problem the temperature is not prescribed, but rather, is determined as part of the solution. We will show that the length of samples in which such self-sustained combustion waves can occur, must exceed a critical value which strongly depends on the combustion temperature T(sub b). Smaller values of T(sub b) require longer sample lengths for diffusion driven combustion waves to exist. Because of their relatively small velocity, diffusion driven waves are considered to be relevant for the case of low heat losses, which occur for large diameter samples or in microgravity conditions, Another possible mechanism of porous medium combustion describes waves which propagate by consuming the oxidizer initially stored in the pores of the sample. This occurs for abnormally high pressure and gas density. In this case, uniformly propagating planar waves, which are kinetically controlled, can propagate, Diffusion of oxidizer decreases

Absorber for terahertz radiation management

Science.gov (United States)

Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

2015-12-08

A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

Aspects of frequency redistribution for non-coherent scattering in a turbulent medium

International Nuclear Information System (INIS)

Magnan, C.

1975-01-01

The scattering of line phonons in a turbulent medium is re-examined. The fact is taken into account that a photon absorbed in a turbulent element having some velocity will be re-emitted by the same element and keeps in that way a certain 'memory' of its absorption. Adding the contributions of all turbulent elements at a given point new redistribution functions are constructed, describing this correlation. They give the probability that a photon with frequency x in the direction n is absorbed and re-emitted at frequency x' in the direction n'. A preliminary discussion of the problem is given in an astrophysical context. (author)

A quantitative modeling of the contributions of localized surface plasmon resonance and interband transitions to absorbance of gold nanoparticles

International Nuclear Information System (INIS)

Zhu, S.; Chen, T. P.; Liu, Y. C.; Liu, Y.; Fung, S.

2012-01-01

A quantitative modeling of the contributions of localized surface plasmon resonance (LSPR) and interband transitions to absorbance of gold nanoparticles has been achieved based on Lorentz–Drude dispersion function and Maxwell-Garnett effective medium approximation. The contributions are well modeled with three Lorentz oscillators. Influence of the structural properties of the gold nanoparticles on the LSPR and interband transitions has been examined. In addition, the dielectric function of the gold nanoparticles has been extracted from the modeling to absorbance, and it is found to be consistent with the result yielded from the spectroscopic ellipsometric analysis.

Absorbed dose determination in external beam radiotherapy. An international code of practice for dosimetry based on standards of absorbed dose to water

International Nuclear Information System (INIS)

2000-01-01

electron beams or are in the stage of developing the necessary techniques for these modalities. Following the recommendations in 1996 of the IAEA Standing Advisory Group Scientific Committee of the IAEA (WHO) SSDL Network, a Co-ordinated Research Project was undertaken during 1997-1999 with the task of producing a new international Code of Practice based on standards of absorbed dose to water. The Code is also endorsed by the World Health Organization, the Pan American Health Organization and the European Society of Therapeutic Radiology and Oncology (ESTRO). The final draft was reviewed by representatives of the organizations endorsing the Code and by a large number of scientists. This Code of Practice fulfils the need for a systematic and internationally unified approach to the calibration of ionization chambers in terms of absorbed dose to water and to the use of these detectors in determining the absorbed dose to water for the radiation beams used in radiotherapy. It provides a methodology for the determination of absorbed dose to water in the low, medium and high energy photon beams, electron beams, proton beams and heavy ion beams used for external radiation therapy. The officer at the IAEA responsible for this Code of Practice was P. Andreo of the Division of Human Health

Utilizing strongly absorbing materials for low-loss surface-wave nonlinear optics

Science.gov (United States)

Grosse, Nicolai B.; Franz, Philipp; Heckmann, Jan; Pufahl, Karsten; Woggon, Ulrike

2018-04-01

Optical media endowed with large nonlinear susceptibilities are highly prized for their employment in frequency conversion and the generation of nonclassical states of light. Although the presence of an optical resonance can greatly increase the nonlinear response (e.g., in epsilon-near-zero materials), the non-negligible increase in linear absorption often precludes the application of such materials in nonlinear optics. Absorbing materials prepared as thin films, however, can support a low-loss surface wave: the long-range surface exciton polariton (LRSEP). Its propagation lifetime increases with greater intrinsic absorption and reduced film thickness, provided that the film is embedded in a transparent medium (symmetric cladding). We explore LRSEP propagation in a molybdenum film by way of a prism-coupling configuration. Our observations show that excitation of the LRSEP mode leads to a dramatic increase in the yield of second-harmonic generation. This implies that the LRSEP mode is an effective vehicle for utilizing the nonlinear response of absorbing materials.

Calculations radiobiological using the quadratic lineal model in the use of the medium dose rate absorbed in brachytherapy. Pt. 3

International Nuclear Information System (INIS)

2002-01-01

Calculations with the quadratic lineal model for medium rate using the equation dose-effect. Several calculations for system of low dose rate brachytherapy plus teletherapy, calculations for brachytherapy with medium dose rate together with teletherapy, dose for fraction and the one numbers of fractions in medium rate

Implementation of a perfect metamaterial absorber into multi-functional sensor applications

Science.gov (United States)

Akgol, O.; Karaaslan, M.; Unal, E.; Sabah, C.

2017-05-01

Perfect metamaterial absorber (MA)-based sensor applications are presented and investigated in the microwave frequency range. It is also experimentally analyzed and tested to verify the behavior of the MA. Suggested perfect MA-based sensor has a simple configuration which introduces flexibility to sense the dielectric properties of a material and the pressure of the medium. The investigated applications include pressure and density sensing. Besides, numerical simulations verify that the suggested sensor achieves good sensing capabilities for both applications. The proposed perfect MA-based sensor variations enable many potential applications in medical or food technologies.

Power plant by deuteron beams using indirect-driven target

International Nuclear Information System (INIS)

Niu, Keishiro

1989-01-01

An indirect-driven target is proposed to be used for 6-beam nonuniform irradiation of deuteron particles. The target consists of 5 layers; tamper, radiator, smoother (radiation gap), absorber (pusher) and solid DT fuel. The fluctuation comes from nonuniform energy deposition in the radiator layer. Through the smoother layer, radiative energy transport from the radiator layer to the absorber layer is expected to smooth out the temperature fluctuation in the absorber layer. The total beam energy of 12 MJ is launched to the target by 6 beams. In order to delete the charge of the front edge of the propagating deuteron beam, the electron beam is proposed to be launched to the target with the same velocity and with the same number density at the same time of the deuteron extraction form the diode. To stabilize the beam propagation, the electron beam has a rotation velocity which induces the magnetic field in the propagation direction. The construction of the power supply system whose total stored energy is 12 MJ seems to be not difficult and to be economical. (author)

Electron absorbed dose comparison between MCNP5 and Penelope Monte Carlo code for microdosimetry

International Nuclear Information System (INIS)

Cintra, Felipe B. de; Yoriyaz, Helio

2009-01-01

The objective of the present work was to compare electron absorbed dose results between two widespread used codes in international scientific community: MCNP5 and Penelope-2003. Individual water spheres with masses between 10 -9 g up to 10 -3 g immersed in an infinite water medium (density of 1g/cm 3 ) and monoenergetic electron sources with energy from 0.002 MeV to 0.1 MeV have been considered. The absorbed dose in the spheres was evaluated by both codes and the relative differences have been quantified. The results shown that Penelope gives, in general, higher results that, in some cases saturate or reach a maximum point and then rapidly drops. Particularly, for the 40 keV electron source we have done additional tests in three different scenarios: more points in the region of lower masses to a better definition of the curve behavior; MCNP used 200 substeps and Penelope was set to a full detail history methodology, and almost same parameters of case B but with the density of exterior medium increased to 10 g/cm 3 . The three cases show the influence of the backscattering that contribute with an important fraction of absorbed dose, finally we can infer a range of reliability to use the codes in this kind of simulations: both codes can calculate close results for up to 10 -4 g.Even though MCNP5 uses the condensed history method, if simulation parameters are chosen carefully it can reproduce results very close to those obtained using detailed history mode. In some cases, the use of higher number of electron substeps causes significant differences in the result. (author)

Hydraulic shock absorbers

International Nuclear Information System (INIS)

Thatcher, G.; Davidson, D. F.

1984-01-01

A hydraulic shock absorber of the dash pot kind for use with electrically conducting liquid such as sodium, has magnet means for electro magnetically braking a stream of liquid discharged from the cylinder. The shock absorber finds use in a liquid metal cooled nuclear reactor for arresting control rods

Reflection measurements of microwave absorbers

Science.gov (United States)

Baker, Dirk E.; van der Neut, Cornelis A.

1988-12-01

A swept-frequency interferometer is described for making rapid, real-time assessments of localized inhomogeneities in planar microwave absorber panels. An aperture-matched exponential horn is used to reduce residual reflections in the system to about -37 dB. This residual reflection is adequate for making comparative measurements on planar absorber panels whose reflectivities usually fall in the -15 to -25 dB range. Reflectivity measurements on a variety of planar absorber panels show that multilayer Jaumann absorbers have the greatest inhomogeneity, while honeycomb absorbers generally have excellent homogeneity within a sheet and from sheet to sheet. The test setup is also used to measure the center frequencies of resonant absorbers. With directional couplers and aperture-matched exponential horns, the technique can be easily applied in the standard 2 to 40 GHz waveguide bands.

Circum-Galactic Medium in the Halo of Quasars

Directory of Open Access Journals (Sweden)

Riccardo Ottolina

2017-12-01

Full Text Available The properties of circum-galactic gas in the halo of quasar host galaxies are investigated analyzing Mg II 2800 and C IV 1540 absorption-line systems along the line of sight close to quasars. We used optical spectroscopy of closely aligned pairs of quasars (projected distance ≤ 200 kpc, but at very different redshift obtained at the VLT and Gran Telescopio Canarias to investigate the distribution of the absorbing gas for a sample of quasars at z ~1. Absorption systems of EW ≥0.3 associated with the foreground quasars are revealed up to 200 kpc from the centre of the host galaxy, showing that the structure of the absorbing gas is patchy with a covering fraction quickly decreasing beyond 100 kpc. In this contribution we use optical and near-IR images obtained at VLT to investigate the relations between the properties of the circum-galactic medium of the host galaxies and of the large scale galaxy environments of the foreground quasars.

Corrosion resistant neutron absorbing coatings

Science.gov (United States)

Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

2012-05-29

A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

PWR burnable absorber evaluation

International Nuclear Information System (INIS)

Cacciapouti, R.J.; Weader, R.J.; Malone, J.P.

1995-01-01

The purpose of the study was to evaluate the relative neurotic efficiency and fuel cycle cost benefits of PWR burnable absorbers. Establishment of reference low-leakage equilibrium in-core fuel management plans for 12-, 18- and 24-month cycles. Review of the fuel management impact of the integral fuel burnable absorber (IFBA), erbium and gadolinium. Calculation of the U 3 O 8 , UF 6 , SWU, fuel fabrication, and burnable absorber requirements for the defined fuel management plans. Estimation of fuel cycle costs of each fuel management plan at spot market and long-term market fuel prices. Estimation of the comparative savings of the different burnable absorbers in dollar equivalent per kgU of fabricated fuel. (author)

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping

2016-05-18

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping; Wu, Ying; Lai, Yun

2016-01-01

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Photon mass drag and the momentum of light in a medium

DEFF Research Database (Denmark)

Partanen, Mikko; Häyrynen, Teppo; Oksanen, Jani

2017-01-01

Conventional theories of electromagnetic waves in a medium assume that the energy propagating with the light pulse in the medium is entirely carried by the field. Thus, the possibility that the optical force field of the light pulse would drive forward an atomic mass density wave (MDW...... field. We show that a light pulse having a total electromagnetic energy (h) over bar omega propagating in a nondispersive medium transfers a mass equal to delta m = (n(2) - 1) (h) over bar omega/c(2), where n is the refractive index. MDW, which carries this mass, consists of atoms, which are more......) and the related kinetic and elastic energies is neglected. In this work, we present foundations of a covariant theory of light propagation in a medium by considering a light wave simultaneously with the dynamics of the medium atoms driven by optoelastic forces between the induced dipoles and the electromagnetic...

Feynman Integrals with Absorbing Boundaries

OpenAIRE

Marchewka, A.; Schuss, Z.

1997-01-01

We propose a formulation of an absorbing boundary for a quantum particle. The formulation is based on a Feynman-type integral over trajectories that are confined to the non-absorbing region. Trajectories that reach the absorbing wall are discounted from the population of the surviving trajectories with a certain weighting factor. Under the assumption that absorbed trajectories do not interfere with the surviving trajectories, we obtain a time dependent absorption law. Two examples are worked ...

Knowledge management driven leadership, culture and innovation success – an integrative model

OpenAIRE

Zieba, M.; Schivinski, Bruno

2015-01-01

Purpose - This article examines the relation between knowledge management (KM) driven leadership, culture and innovation success of knowledge-intensive small and medium sized companies. By building on the previously reported research on leadership, culture, innovation , and knowledge management, we synergistically integrate d KM-driven leadership and innovation success while exploring the meditational role of culture in that. Design/methodology/approach - A conceptual model comprising three c...

Light-powered micromotor driven by geometry-assisted, asymmetric photon-heating and subsequent gas convection

Science.gov (United States)

Han, Li-Hsin; Wu, Shaomin; Condit, J. Christopher; Kemp, Nate J.; Milner, Thomas E.; Feldman, Marc D.; Chen, Shaochen

2010-05-01

We report on the design, fabrication, and analysis of a light-driven micromotor. The micromotor was created from a nanoporous polymer with close-packed gold nanoparticles which generate heat by absorbing light. The blades of the micromotor were curved, forming convex and concave sides. Upon lateral irradiation, by geometric effect the convex side transfers more photon-generated heat to the surrounding gas molecules, causing a convective motion of gas and leading to the rotation of the micromotor. The light-driven motions of gas molecules were analyzed using molecular dynamics modeling.

Visible light broadband perfect absorbers

Energy Technology Data Exchange (ETDEWEB)

Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O., E-mail: wxo@hit.edu.cn [School of Science, Harbin Institute of Technology, Harbin 150001 (China)

2016-03-15

The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

VERTICAL STRUCTURE OF A SUPERNOVA-DRIVEN TURBULENT, MAGNETIZED INTERSTELLAR MEDIUM

International Nuclear Information System (INIS)

Hill, Alex S.; Matthew Haffner, L.; Ryan Joung, M.; Mac Low, Mordecai-Mark; Benjamin, Robert A.; Klingenberg, Christian; Waagan, Knut

2012-01-01

Stellar feedback drives the circulation of matter from the disk to the halo of galaxies. We perform three-dimensional magnetohydrodynamic simulations of a vertical column of the interstellar medium with initial conditions typical of the solar circle in which supernovae drive turbulence and determine the vertical stratification of the medium. The simulations were run using a stable, positivity-preserving scheme for ideal MHD implemented in the FLASH code. We find that the majority (≈90%) of the mass is contained in thermally stable temperature regimes of cold molecular and atomic gas at T 4.2 K, with strong peaks in probability distribution functions of temperature in both the cold and warm regimes. The 200-10 4.2 K gas fills 50%-60% of the volume near the plane, with hotter gas associated with supernova remnants (30%-40%) and cold clouds ( 5 K) gas accounts for most of the mass and volume, while hot gas dominates at |z| > 3 kpc. The magnetic field in our models has no significant impact on the scale heights of gas in each temperature regime; the magnetic tension force is approximately equal to and opposite the magnetic pressure, so the addition of the field does not significantly affect the vertical support of the gas. The addition of a magnetic field does reduce the fraction of gas in the cold ( 4 K) gas. However, our models lack rotational shear and thus have no large-scale dynamo, which reduces the role of the field in the models compared to reality. The supernovae drive oscillations in the vertical distribution of halo gas, with the period of the oscillations ranging from ≈30 Myr in the T 6 K gas, in line with predictions by Walters and Cox.

Optimization of sound absorbing performance for gradient multi-layer-assembled sintered fibrous absorbers

Science.gov (United States)

Zhang, Bo; Zhang, Weiyong; Zhu, Jian

2012-04-01

The transfer matrix method, based on plane wave theory, of multi-layer equivalent fluid is employed to evaluate the sound absorbing properties of two-layer-assembled and three-layer-assembled sintered fibrous sheets (generally regarded as a kind of compound absorber or structures). Two objective functions which are more suitable for the optimization of sound absorption properties of multi-layer absorbers within the wider frequency ranges are developed and the optimized results of using two objective functions are also compared with each other. It is found that using the two objective functions, especially the second one, may be more helpful to exert the sound absorbing properties of absorbers at lower frequencies to the best of their abilities. Then the calculation and optimization of sound absorption properties of multi-layer-assembled structures are performed by developing a simulated annealing genetic arithmetic program and using above-mentioned objective functions. Finally, based on the optimization in this work the thoughts of the gradient design over the acoustic parameters- the porosity, the tortuosity, the viscous and thermal characteristic lengths and the thickness of each samples- of porous metals are put forth and thereby some useful design criteria upon the acoustic parameters of each layer of porous fibrous metals are given while applying the multi-layer-assembled compound absorbers in noise control engineering.

STAR FORMATION FEEDBACK AND METAL-ENRICHMENT HISTORY OF THE INTERGALACTIC MEDIUM

International Nuclear Information System (INIS)

Cen Renyue; Chisari, Nora Elisa

2011-01-01

Using the state-of-the-art cosmological hydrodynamic simulations of the standard cold dark matter model with star formation feedback strength normalized to match the observed star formation history of the universe at z= 0-6, we compute the metal-enrichment history of the intergalactic medium (IGM). Overall we show that galactic superwind (GSW) feedback from star formation can transport metals to the IGM and that the properties of simulated metal absorbers match current observations. The distance of influence of GSW from galaxies is typically limited to about ≤0.5 Mpc and within regions of overdensity δ ≥ 10. Most C IV and O VI absorbers are located within shocked regions of elevated temperature (T ≥ 2 x 10 4 K), overdensity (δ ≥ 10), and metallicity ([Z/Z sun ] = [ - 2.5, - 0.5]), enclosed by double shocks propagating outward. O VI absorbers have typically higher metallicity, lower density, and higher temperature than C IV absorbers. For O VI absorbers, collisional ionization dominates over the entire redshift range z= 0-6, whereas for C IV absorbers the transition occurs at moderate redshift z ∼ 3 from collisionally dominated to photoionization dominated. We find that the observed column density distributions for C IV and O VI in the range log N cm 2 =12-15 are reasonably reproduced by the simulations. The evolution of mass densities contained in C IV and O VI lines, Ω CIV and Ω OVI , is also in good agreement with observations, which shows a near constancy at low redshifts and an exponential drop beyond redshift z= 3-4. For both C IV and O VI, most absorbers are transient and the amount of metals probed by C IV and O VI lines of column log N cm 2 =12-15 is only ∼2% of total metal density at any epoch. While gravitational shocks from large-scale structure formation dominate the energy budget (80%-90%) for turning about 50% of the IGM to the warm-hot intergalactic medium (WHIM) by z = 0, GSW feedback shocks are energetically dominant over

Neutron Absorbing Ability Variation in Neutron Absorbing Material Caused by the Neutron Irradiation in Spent Fuel Storage Facility

Energy Technology Data Exchange (ETDEWEB)

Sohn, Hee Dong; Han, Seul Gi; Lee, Sang Dong; Kim, Ki Hong; Ryu, Eag Hyang; Park, Hwa Gyu [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

2014-10-15

In spent fuel storage facility like high density spent fuel storage racks and dry storage casks, spent fuels are stored with neutron absorbing materials installed as a part of those facilities, and they are used for absorbing neutrons emitted from spent fuels. Usually structural material with neutron absorbing material of racks and casks are located around spent fuels, so it is irradiated by neutrons for long time. Neutron absorbing ability could be changed by the variation of nuclide composition in neutron absorbing material caused by the irradiation of neutrons. So, neutron absorbing materials are continuously faced with spent fuels with boric acid solution or inert gas environment. Major nuclides in neutron absorbing material are Al{sup 27}, C{sup 12}, B{sup 11}, B{sup 10} and they are changed to numerous other ones as radioactive decay or neutron absorption reaction. The B{sup 10} content in neutron absorbing material dominates the neutron absorbing ability, so, the variation of nuclide composition including the decrease of B{sup 10} content is the critical factor on neutron absorbing ability. In this study, neutron flux in spent fuel, the activation of neutron absorbing material and the variation of nuclide composition are calculated. And, the minimum neutron flux causing the decrease of B{sup 10} content is calculated in spent fuel storage facility. Finally, the variation of neutron multiplication factor is identified according to the one of B{sup 10} content in neutron absorbing material. The minimum neutron flux to impact the neutron absorbing ability is 10{sup 10} order, however, usual neutron flux from spent fuel is 10{sup 8} order. Therefore, even though neutron absorbing material is irradiated for over 40 years, B{sup 10} content is little decreased, so, initial neutron absorbing ability could be kept continuously.

Sound Absorbers

Science.gov (United States)

Fuchs, H. V.; Möser, M.

Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

Monte Carlo simulation of reflection spectra of random multilayer media strongly scattering and absorbing light

International Nuclear Information System (INIS)

Meglinskii, I V

2001-01-01

The reflection spectra of a multilayer random medium - the human skin - strongly scattering and absorbing light are numerically simulated. The propagation of light in the medium and the absorption spectra are simulated by the stochastic Monte Carlo method, which combines schemes for calculations of real photon trajectories and the statistical weight method. The model takes into account the inhomogeneous spatial distribution of blood vessels, water, and melanin, the degree of blood oxygenation, and the hematocrit index. The attenuation of the incident radiation caused by reflection and refraction at Fresnel boundaries of layers inside the medium is also considered. The simulated reflection spectra are compared with the experimental reflection spectra of the human skin. It is shown that a set of parameters that was used to describe the optical properties of skin layers and their possible variations, despite being far from complete, is nevertheless sufficient for the simulation of the reflection spectra of the human skin and their quantitative analysis. (laser applications and other topics in quantum electronics)

Study of molybdenum(VI) dimerization equilibrium in strongly acidic medium

International Nuclear Information System (INIS)

Esbelin, E.

2000-01-01

Molybdenum (VI) was investigated spectro-photometrically in non complexing and strongly acidic medium for the first time by Krumenacker. Cationic species of molybdenum were identified by electrophoresis on cellulose paper in highly acidic solutions. From these early results using absorption spectrophotometry, Krumenacker postulated the condensation of molybdenum in this medium. He studied the polymeric species by measuring diffusion coefficients and identified the polymeric form as a dimer. He described the system by equations (1) and (2). Cruywagen later added two equations (3) and (4) to supplement the description of the system. The aim of this work was to re-examine the conditional dimerization equilibrium between the various species of molybdenum(VI) in strongly acid medium by focussing on the influence of the medium. All Mo solution concentrations were analyzed by ICP-AES. Absorbance of the solutions were measured with a VARIAN model CARY5 spectrophotometer in double beam mode with air as reference; blank solutions contained all reagents except molybdenum. The quartz cell path length was 1 mm. The dimerization of monomeric molybdenum(VI) was investigated spectro-photometrically at perchloric acid concentrations of 0.5, 1.0, 2.0 and 3 M at 25 deg C. Two absorption bands at 215 and 245 nm were observed and attributed to monomeric and dimeric forms respectively. The variations in the conditional molar absorption coefficient of molybdenum with total molybdenum(VI) concentration is indicative of several molybdenum forms involved in the total absorbance. Dimerization equilibrium is defined by equation (5). By using the additivity of absorbance and mass conservation of molybdenum, a descriptive equation of the 'spectrochemical' system is developed. This equation is linearized into two forms (6) et (7). From them, two refinement methods were used to estimate the conditional dimerization constant K' d for various medium concentrations. This numerical procedure offers

Electrically Driven Photonic Crystal Nanocavity Devices

Science.gov (United States)

2012-01-01

material, here gallium arsenide and indium arsenide self- assembled quantum dots (QDs). QDs are preferred for the gain medium because they can have...blue points ) and 150 K (green points ). The black lines are linear fits to the above threshold output power of the lasers, which are used to find the...SHAMBAT et al.: ELECTRICALLY DRIVEN PHOTONIC CRYSTAL NANOCAVITY DEVICES 1707 Fig. 13. (a) Tilted SEM picture of a fabricated triple cavity device. The in

Neutron absorbing article

International Nuclear Information System (INIS)

Naum, R.G.; Owens, D.P.; Dooher, G.I.

1979-01-01

A neutron absorbing article, in flat plate form and suitable for use in a storage rack for spent fuel, includes boron carbide particles, diluent particles and a solid, irreversibly cured phenolic polymer cured to a continuous matrix binding the boron carbide and diluent particles. The total conent of boron carbide and diluent particles is a major proportion of the article and the content of cured phenolic polymer present is a minor proportion. By regulation of the ratio of boron carbide particles to diluent particles, normally within the range of 1:9 and 9:1 and preferably within the range of 1:5 to 5:1, the neutron absorbing activity of the product may be controlled, which facilitates the manufacture of articles of particular absorbing activities best suitable for specific applications

Hysteresis in pressure-driven DNA denaturation.

Directory of Open Access Journals (Sweden)

Enrique Hernández-Lemus

Full Text Available In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue.

Exhaust of plant oil fuelled cogeneration unit drives a two-stage refrigerating absorber; Abgas aus Pflanzenoel-BHKW treibt zweistufige Absorptionskaeltemaschine an

Energy Technology Data Exchange (ETDEWEB)

Schmid, W.

2008-05-15

Skating rinks are expensive to operate. In view of exploding energy prices, energetic optimisation is economically favourable even in more recent buildings. In the Hacker-Pschorr-Arena building at Bad Toelz, which was commissioned in 2004, the space HVAC system was modernized. A plant oil fuelled cogeneration unit and an exhaust-driven two-stage refrigerating absorber were installed. (orig.)

Radiation sterilization of absorbent cotton and of absorbent gauze

International Nuclear Information System (INIS)

Hosobuchi, Kazunari; Oka, Mitsuru; Kaneko, Akira; Ishiwata, Hiroshi.

1986-01-01

The bioburden of absorbent cotton and of absorbent gauze and their physical and chemical characteristics after irradiation are investigated. The survey conducted on contaminants of 1890 cotton samples from 53 lots and 805 gauze samples from 56 lots showed maximum numbers of microbes per g of the cotton and gauze were 859 (an average of 21.4) and 777 (an average of 42.2), respectively. Isolation and microbiological and biochemical tests of representative microbes indicated that all of them, except one, were bacilli. The sterilization dose at 10 -6 of sterlity assurance level was found to be 2.0 Mrad when irradiated the spores loaded on paper strips and examined populations having graded D values from 0.10 to 0.28 Mrad. The sterilization dose would be about 1.5 Mrad if subjected the average numbers of contaminants observed in this study to irradiation. No significant differences were found between the irradiated samples and control up to 2 Mrad in tensile strength, change of color, absorbency, sedimentation rate, soluble substances, and pH of solutions used for immersion and other tests conventionally used. These results indicate that these products can be sterilized by irradiation. (author)

Radiative and conductive heat transfer in a nongrey semitransparent medium. Application to fire protection curtains

Energy Technology Data Exchange (ETDEWEB)

Berour, Nacer; Lacroix, David E-mail: david.lacroix@lemta.uhp-nancy.fr; Boulet, Pascal; Jeandel, Gerard

2004-06-01

This paper deals with heat transfer in nongrey media which scatter, absorb and emit radiation. Considering a two dimensional geometry, radiative and conductive phenomena through the medium have been taken into account. The radiative part of the problem was solved using the discrete ordinate method with classical S{sub n} quadratures. The absorption and scattering coefficients involved in the radiative transfer equation (RTE) were obtained from the Mie theory. Conduction inside the medium was linked to the RTE through the energy conservation. Validation of the model has been achieved with several simulation of water spray curtains used as fire protection walls.

A preliminary investigation on the epithermal flux depression effect due to cadmium box in a multiplying medium

International Nuclear Information System (INIS)

Ahmad, A.

1983-01-01

Cadmium boxes are widely used as filter in Reactor Neutron Activation Analysis (RNAA) for the irradiation of samples in epithermal neutrons. By virtue of being an absorber the cadmium boxes produce epithermal flux depression in the medium surrounding them. A preliminary study of this effect was carried out (author)

Clinical outcomes of patients with diabetes mellitus treated with Absorb bioresorbable vascular scaffolds: a subanalysis of the European Multicentre GHOST-EU Registry.

Science.gov (United States)

Capranzano, Piera; Capodanno, Davide; Brugaletta, Salvatore; Latib, Azeem; Mehilli, Julinda; Nef, Holger; Gori, Tommaso; Lesiak, Maciej; Geraci, Salvatore; Pyxaras, Stelios; Mattesini, Alessio; Münzel, Thomas; Araszkiewicz, Aleksander; Caramanno, Giuseppe; Naber, Christoph; Di Mario, Carlo; Sabatè, Manel; Colombo, Antonio; Wiebe, Jens; Tamburino, Corrado

2018-02-15

Data on the clinical performance of bioresorbable scaffolds in patients with diabetes mellitus (DM) are still limited. The present study reported 1-year clinical outcomes associated with the use of everolimus-eluting bioresorbable vascular scaffolds (Absorb BVS; Abbott Vascular, Santa Clara, CA) in DM patients. This was a subanalysis from the GHOST-EU (Gauging coronary Healing with biOresorbable Scaffolding plaTforms in Europe) multicenter retrospective registry including patients treated with Absorb BVS between November 2011 and September 2014. In this study, a comparative analysis stratified according to DM was performed. The primary endpoint was target lesion failure (TLF), defined as the combination of cardiac death, target-vessel myocardial infarction (MI) and clinically-driven target-lesion revascularization (TLR). A total of 1,477 patients were treated with 2,224 Absorb BVS; 381 (25.8%) and 1,096 (74.2%) patients were with and without DM, respectively. The 1-year rate of TLF was higher among patients with DM (7.8%) than those without DM (4.3%); the increase in TLF was driven by TLR (6.5% vs. 3.3%, P = 0.009); no significant differences in cardiac death (1.1% vs. 0.9%, P = 0.68) and target-vessel MI (3.1% vs. 2.2%, P = 0.38) were observed, respectively. Definite/probable scaffold thrombosis rate tended to be higher among patients with DM than those without DM (3.0% vs. 1.7%, P = 0.14, respectively). Absorb BVS use in patients with DM was associated with increased 1-year TLF and scaffold thrombosis compared with non-diabetes patients. © 2017 Wiley Periodicals, Inc.

Preparation of Active Absorbent for Flue Gas Desulfurization From Coal Bottom Ash: Effect of Absorbent Preparation Variables

Directory of Open Access Journals (Sweden)

Chang Chin Li, Lee Keat Teong, Subhash Bhatia and Abdul Rahman Mohamed

2012-08-01

Full Text Available An active absorbent for flue gas desulfurization was prepared from coal bottom ash, calcium oxide (CaO and calcium sulfate by hydro-thermal process. The absorbent was examined for its micro-structural properties. The experiments conducted were based on Design Of Experiments (DOE according to 23 factorial design. The effect of various absorbent preparation variables such as ratio of CaO to bottom ash (A, hydration temperature (B and hydration period (C towards the BET (Brunauer-Emmett-Teller specific surface area of the absorbent were studied. At a CaO to bottom ash ratio = 2, hydration temperature = 200 ?C and hydration period = 10 hrs, absorbent with a surface area of 90.1 m2/g was obtained. Based on the analysis of the factorial design, it was concluded that factor A and C as well as the interaction of factors ABC and BC are the significant factors that effect the BET surface area of the absorbent. A linear mathematical model that describes the relation between the independent variables and interaction between variables towards the BET specific surface area of the absorbent was also developed. Analysis of variance (ANOVA showed that the model was significant at 1% level.Key Words: Absorbent, Bottom Ash, Design Of Experiments, Desulfurization, Surface Area.

Distribution of medium-chain FA in different lipid classes after administration of specific structured TAG in rats

DEFF Research Database (Denmark)

Mu, Huiling; Høy, Carl-Erik

2002-01-01

Structured TAG (STAG) containing medium-chain FA (MCFA) in the sn-1,3 positions and essential FA in the sn-2 position were synthesized by lipase-catalyzed acidolysis. In our previous studies we found that part of the MCFA from STAG could be absorbed in the small intestine; however, it was unclear...... how they were absorbed. In order to get a better understanding of the metabolism of STAG to improve future design and application of STAG, in the present study lymph lipids collected after feeding STAG were fractionated into different classes and the FA composition of each lipid class was studied...

Modeling Shocks Detected by Voyager 1 in the Local Interstellar Medium

Energy Technology Data Exchange (ETDEWEB)

Kim, T. K.; Pogorelov, N. V. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Burlaga, L. F. [NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 (United States)

2017-07-10

The magnetometer (MAG) on Voyager 1 ( V1 ) has been sampling the interstellar magnetic field (ISMF) since 2012 August. The V1 MAG observations have shown draped ISMF in the very local interstellar medium disturbed occasionally by significant enhancements in magnetic field strength. Using a three-dimensional, data-driven, multi-fluid model, we investigated these magnetic field enhancements beyond the heliopause that are supposedly associated with solar transients. To introduce time-dependent effects at the inner boundary at 1 au, we used daily averages of the solar wind parameters from the OMNI data set. The model ISMF strength, direction, and proton number density are compared with V1 data beyond the heliopause. The model reproduced the large-scale fluctuations between 2012.652 and 2016.652, including major events around 2012.9 and 2014.6. The model also predicts shocks arriving at V1 around 2017.395 and 2019.502. Another model driven by OMNI data with interplanetary coronal mass ejections (ICMEs) removed at the inner boundary suggests that ICMEs may play a significant role in the propagation of shocks into the interstellar medium.

COINCIDENCES BETWEEN O VI AND O VII LINES: INSIGHTS FROM HIGH-RESOLUTION SIMULATIONS OF THE WARM-HOT INTERGALACTIC MEDIUM

International Nuclear Information System (INIS)

Cen Renyue

2012-01-01

With high-resolution (0.46 h –1 kpc), large-scale, adaptive mesh-refinement Eulerian cosmological hydrodynamic simulations we compute properties of O VI and O VII absorbers from the warm-hot intergalactic medium (WHIM) at z = 0. Our new simulations are in broad agreement with previous simulations with ∼40% of the intergalactic medium being in the WHIM. Our simulations are in agreement with observed properties of O VI absorbers with respect to the line incidence rate and Doppler-width-column-density relation. It is found that the amount of gas in the WHIM below and above 10 6 K is roughly equal. Strong O VI absorbers are found to be predominantly collisionally ionized. It is found that (61%, 57%, 39%) of O VI absorbers of log N(O VI) cm 2 = (12.5-13, 13-14, > 14) have T 5 K. Cross correlations between galaxies and strong [N(O VI) > 10 14 cm –2 ] O VI absorbers on ∼100-300 kpc scales are suggested as a potential differentiator between collisional ionization and photoionization models. Quantitative prediction is made for the presence of broad and shallow O VI lines that are largely missed by current observations but will be detectable by Cosmic Origins Spectrograph observations. The reported 3σ upper limit on the mean column density of coincidental O VII lines at the location of detected O VI lines by Yao et al. is above our predicted value by a factor of 2.5-4. The claimed observational detection of O VII lines by Nicastro et al., if true, is 2σ above what our simulations predict.

Absorbed dose distributions in patients with bone metastases from hormone refractory prostate cancer treated with Re-186 HEDP

International Nuclear Information System (INIS)

Denis Bacelar, A.M.; Dearnaley, D.P.; Divoli, A.; Chittenden, S.; Du, Y.; Flux, G.D.; O'Sullivan, J.M.

2015-01-01

Full text of publication follows. Aim: intravenous administration of Re-186 hydroxyethylidene-diphosphonate (HEDP) is used for metastatic bone pain palliation in hormone refractory prostate cancer patients. Dosimetry for bone seeking radionuclides is challenging due to the complex structure with osteoblastic, osteolytic and mixed lesions. The aim of this study was to perform image-based patient-specific 3D convolution dosimetry to obtain a distribution of the absorbed doses to each lesion and estimate inter- and intra-patient variations. Materials and methods: 28 patients received a fixed 5 GBq activity of Re-186 HEDP followed by peripheral blood stem cell rescue at 14 days in a phase II trial. A FORTE dual-headed gamma camera was used to acquire sequential Single-Photon-Emission Computed Tomography (SPECT) data of the thorax and pelvis area at 1, 4, 24, 48 and 72 hours following administration. The projection data were reconstructed using filtered-back projection and were corrected for attenuation and scatter. Voxelised cumulated activity distributions were obtained with two different methods. First, the scans were co-registered and the time-activity curves were obtained on a voxel-by-voxel basis. Second, the clearance curve was obtained from the mean number of counts in each individual lesion and used to scale the uptake distribution taken at 24 hours. The calibration factors required for image quantification were obtained from a phantom experiment. An in-house developed EGSnrc Monte Carlo code was used for the calculation of dose voxel kernels for soft-tissue and cortical/trabecular bone used to perform convolution dosimetry. Cumulative dose-volume histograms were produced and mean absorbed doses calculated for each spinal and pelvic lesion. Results: preliminary results show that the lesion mean absorbed doses ranged from 25 to 55 Gy when the medium was soft tissue and decreased by 40% if bone was considered. The use of the cumulated activity distribution

Transport in coherently absorbing or amplifying media

International Nuclear Information System (INIS)

Sen, A.K.

1995-11-01

We study electronic transport in a one-dimensional ordered chain in the presence of either absorption or amplification at each site (the site-potential having an imaginary positive or negative part) within a single-band tightbinding Hamiltonian. The spectrum in either case for the isolated (closed) quantum system is found to become broader compared to the regular Bloch case where there is no absorption or amplification at any site. Interestingly for the transport through an infinitely long ordered chain (open quantum system), the reflectance saturates to a value greater (lesser) than unity in the amplifying (absorbing) case and the transmittance decays to zero in either case. This fact implies that the transmittance does not grow indefinitely even for an ordered, amplifying (active or lasing) medium and that it is not necessary to have any disorder or interaction induced confining mechanism on the transmitted wave, so as to achieve an amplification in the backscattered wave. (author). 8 refs, 2 figs

Dynamic Data-Driven Reduced-Order Models of Macroscale Quantities for the Prediction of Equilibrium System State for Multiphase Porous Medium Systems

Science.gov (United States)

Talbot, C.; McClure, J. E.; Armstrong, R. T.; Mostaghimi, P.; Hu, Y.; Miller, C. T.

2017-12-01

Microscale simulation of multiphase flow in realistic, highly-resolved porous medium systems of a sufficient size to support macroscale evaluation is computationally demanding. Such approaches can, however, reveal the dynamic, steady, and equilibrium states of a system. We evaluate methods to utilize dynamic data to reduce the cost associated with modeling a steady or equilibrium state. We construct data-driven models using extensions to dynamic mode decomposition (DMD) and its connections to Koopman Operator Theory. DMD and its variants comprise a class of equation-free methods for dimensionality reduction of time-dependent nonlinear dynamical systems. DMD furnishes an explicit reduced representation of system states in terms of spatiotemporally varying modes with time-dependent oscillation frequencies and amplitudes. We use DMD to predict the steady and equilibrium macroscale state of a realistic two-fluid porous medium system imaged using micro-computed tomography (µCT) and simulated using the lattice Boltzmann method (LBM). We apply Koopman DMD to direct numerical simulation data resulting from simulations of multiphase fluid flow through a 1440x1440x4320 section of a full 1600x1600x5280 realization of imaged sandstone. We determine a representative set of system observables via dimensionality reduction techniques including linear and kernel principal component analysis. We demonstrate how this subset of macroscale quantities furnishes a representation of the time-evolution of the system in terms of dynamic modes, and discuss the selection of a subset of DMD modes yielding the optimal reduced model, as well as the time-dependence of the error in the predicted equilibrium value of each macroscale quantity. Finally, we describe how the above procedure, modified to incorporate methods from compressed sensing and random projection techniques, may be used in an online fashion to facilitate adaptive time-stepping and parsimonious storage of system states over time.

Preliminary design of seawater and brackish water reverse osmosis desalination systems driven by low-temperature solar organic Rankine cycles (ORC)

International Nuclear Information System (INIS)

Delgado-Torres, Agustin M.; Garcia-Rodriguez, Lourdes

2010-01-01

In this paper, the coupling between the low-temperature solar organic Rankine cycle (ORC) and seawater and brackish water reverse osmosis desalination units has been carried out. Four substances have been considered as working fluids of the solar cycle (butane, isopentane, R245fa and R245ca). With these four fluids the volumetric flow of fresh water produced per unit of aperture area of stationary solar collector has been calculated. The former has been made with the optimized direct vapour generation (DVG) configuration and heat transfer fluid (HTF) configuration of the solar ORC. In the first one (DVG), working fluid of the ORC is directly heated inside the absorber of the solar collector. In the second one (HTF), a fluid different than the working fluid of the ORC (water in this paper) is heated without phase change inside the absorber of the solar collector. Once this fluid has been heated it is carried towards a heat exchanger where it is cooled. Thermal energy delivered in this cooling process is transferred to the working fluid of the ORC. Influence of condensation temperature of the ORC and regeneration's process effectiveness over productivity of the system has also been analysed. Finally, parameters of several preliminary designs of the low-temperature solar thermal driven RO desalination are supplied. R245fa is chosen as working fluid of the ORC in these preliminary designs. The information of the proposed preliminary designs can also be used, i.e., for the assessment of the use of thermal energy rejected by the solar cycle. Overall analysis of the efficiency of the solar thermal driven RO desalination technology is given with the results presented in this paper and the results obtained with the medium temperature solar thermal RO desalination system presented by the authors in previous papers. This work has been carried out within the framework of the OSMOSOL and POWERSOL projects.

Preliminary design of seawater and brackish water reverse osmosis desalination systems driven by low-temperature solar organic Rankine cycles (ORC)

Energy Technology Data Exchange (ETDEWEB)

Delgado-Torres, Agustin M. [Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas, Escuela Tecnica Superior de Ingenieria Civil e Industrial, Universidad de La Laguna (ULL), Avda. Astrofisico Francisco Sanchez s/n. 38206 La Laguna (Tenerife) (Spain); Garcia-Rodriguez, Lourdes [Dpto. Ingenieria Energetica, Universidad de Sevilla Escuela Tecnica Superior de Ingenieros, Camino de los Descubrimientos, s/n 41092 Sevilla (Spain)

2010-12-15

In this paper, the coupling between the low-temperature solar organic Rankine cycle (ORC) and seawater and brackish water reverse osmosis desalination units has been carried out. Four substances have been considered as working fluids of the solar cycle (butane, isopentane, R245fa and R245ca). With these four fluids the volumetric flow of fresh water produced per unit of aperture area of stationary solar collector has been calculated. The former has been made with the optimized direct vapour generation (DVG) configuration and heat transfer fluid (HTF) configuration of the solar ORC. In the first one (DVG), working fluid of the ORC is directly heated inside the absorber of the solar collector. In the second one (HTF), a fluid different than the working fluid of the ORC (water in this paper) is heated without phase change inside the absorber of the solar collector. Once this fluid has been heated it is carried towards a heat exchanger where it is cooled. Thermal energy delivered in this cooling process is transferred to the working fluid of the ORC. Influence of condensation temperature of the ORC and regeneration's process effectiveness over productivity of the system has also been analysed. Finally, parameters of several preliminary designs of the low-temperature solar thermal driven RO desalination are supplied. R245fa is chosen as working fluid of the ORC in these preliminary designs. The information of the proposed preliminary designs can also be used, i.e., for the assessment of the use of thermal energy rejected by the solar cycle. Overall analysis of the efficiency of the solar thermal driven RO desalination technology is given with the results presented in this paper and the results obtained with the medium temperature solar thermal RO desalination system presented by the authors in previous papers. This work has been carried out within the framework of the OSMOSOL and POWERSOL projects. (author)

Heat jettisoning from solar-thermal driven LiBr-H{sub 2}O absorber cooling units by pulsed spraying a dry cooler with water; Waermeabwurf aus einer solarthermisch getriebenen LiBr- H{sub 2}O Absorptionskaeltemaschine durch gepulstes Bespruehen eines Trockenkuehlers mit Wasser

Energy Technology Data Exchange (ETDEWEB)

Gantenbein, P.; Helfenberger, R.; Frank, E.

2010-07-01

This short, illustrated final report discusses the removal of heat from solar-thermal driven LiBr-H{sub 2}O absorber cooling units by pulsed spraying a dry cooler with water. The reduction of electricity consumption for room cooling using conventional chillers is examined. Heat dissipation using open cooling towers and the disadvantages encountered are compared with heat dissipation using a dry cooler with heat-exchanger and fans. Additional evaporation cooling achieved by spraying the heat exchanger with water is described and discussed. The results of measurements made at the Institute for Solar Technology in Rapperswil, Switzerland, are presented and discussed.

Burnable neutron absorbers

International Nuclear Information System (INIS)

Radford, K.C.; Carlson, W.G.

1983-01-01

A neutron-absorber body for use in burnable poison rods in a nuclear reactor. The body is composed of a matrix of Al 2 O 3 containing B 4 C, the neutron absorber. Areas of high density polycrystalline Al 2 O 3 particles are predominantly encircled by pores in some of which there are B 4 C particles. This body is produced by initially spray drying a slurry of A1 2 O 3 powder to which a binder has been added. The powder of agglomerated spheres of the A1 2 O 3 with the binder are dry mixed with B 4 C powder. The mixed powder is formed into a green body by isostatic pressure and the green body is sintered. The sintered body is processed to form the neutron-absorber body. In this case the B 4 C particles are separate from the spheres resulting from the spray drying instead of being embedded in the sphere

Neutron absorbers and methods of forming at least a portion of a neutron absorber

Energy Technology Data Exchange (ETDEWEB)

Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

2014-12-02

Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

Energy Technology Data Exchange (ETDEWEB)

Kumar, A; Verma, G S.P. [Ranchi Coll. (India). Dept. of Chemistry

1975-12-01

Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber.

Laser-driven polarized H/D sources and targets

International Nuclear Information System (INIS)

Clasie, B.; Crawford, C.; Dutta, D.; Gao, H.; Seely, J.; Xu, W.

2005-01-01

Traditionally, Atomic Beam Sources are used to produce targets of nuclear polarized hydrogen (H) or deuterium (D) for experiments using storage rings. Laser-Driven Sources (LDSs) offer a factor of 20-30 gain in the target thickness (however, with lower polarization) and may produce a higher overall figure of merit. The LDS is based on the technique of spin-exchange optical pumping where alkali vapor is polarized by absorbing circularly polarized laser photons. The H or D atoms are nuclear-polarized through spin-exchange collisions with the polarized alkali vapor and through subsequent hyperfine interactions during frequent H-H or D-D collisions

Radioactive iodine absorbing properties of tetrathiafulvalene

Energy Technology Data Exchange (ETDEWEB)

Ito, Tomiyasu; Nakamura, Asao (Ajinomoto Co. Inc., Kawasaki, Kanagawa (Japan). Central Research Labs.); Nogawa, Norio; Oohashi, Kunio; Morikawa, Naotake

1989-05-01

For the purpose of searching some effective absorbents of gaseous radioactive iodine, 16 substances considered as having an affinity for iodine were investigated with regular iodine and /sup 125/I. In a preliminary survey, only tetrathiafulvalene (TTF) was found to have satisfactory absorbing properties comparable to activated charcoal. A further detailed comparison of the properties between TTF and activated charcoal led us to the conclusion that the former has more preferable properties as absorbent of radioactive iodine than the latter in all points studied. The results are summarized as follows: (1) The absorption of iodine on TTF in atmosphere was about twice as much as that on activated charcoal. Desorption of iodine from saturatedly absorbed iodine on TTF was practically negligible except trace amount of initial desorption, while that on activated charcoal was considerable (3%/50h) even in the air at room temperature. (2) Absorbed amount of iodine on activated charcoal decreased with increasing gaseous iodine concentration, air flow rate, on humidity of flowing-air. On the other hand, those factors scarcely affected that on TTF. Under an air flow rate of 1m/s, activated charcoal absorbs only 80% of iodine, while TTF absorbs more than 99%. (3) In flowing-air saturated with water vapor, iodine absorbed on activated charcoal was gradually liberated although by small amount (0.08%/100h), while that on TTF was much more stable for a long period (0.004%/100h). As a conclusion, TTF is considered to be useful as a quite effective radioactive iodine absorbent, especially in the case where protection from radioactive iodine should be serious, though it is expensive now. (author).

Radioactive iodine absorbing properties of tetrathiafulvalene

International Nuclear Information System (INIS)

Ito, Tomiyasu; Nakamura, Asao; Nogawa, Norio; Oohashi, Kunio; Morikawa, Naotake.

1989-01-01

For the purpose of searching some effective absorbents of gaseous radioactive iodine, 16 substances considered as having an affinity for iodine were investigated with regular iodine and 125 I. In a preliminary survey, only tetrathiafulvalene (TTF) was found to have satisfactory absorbing properties comparable to activated charcoal. A further detailed comparison of the properties between TTF and activated charcoal led us to the conclusion that the former has more preferable properties as absorbent of radioactive iodine than the latter in all points studied. The results are summarized as follows: (1) The absorption of iodine on TTF in atmosphere was about twice as much as that on activated charcoal. Desorption of iodine from saturatedly absorbed iodine on TTF was practically negligible except trace amount of initial desorption, while that on activated charcoal was considerable (3%/50h) even in the air at room temperature. (2) Absorbed amount of iodine on activated charcoal decreased with increasing gaseous iodine concentration, air flow rate, on humidity of flowing-air. On the other hand, those factors scarcely affected that on TTF. Under an air flow rate of 1m/s, activated charcoal absorbs only 80% of iodine, while TTF absorbs more than 99%. (3) In flowing-air saturated with water vapor, iodine absorbed on activated charcoal was gradually liberated although by small amount (0.08%/100h), while that on TTF was much more stable for a long period (0.004%/100h). As a conclusion, TTF is considered to be useful as a quite effective radioactive iodine absorbent, especially in the case where protection from radioactive iodine should be serious, though it is expensive now. (author)

Neutron absorbing article

International Nuclear Information System (INIS)

Naum, R.G.; Owens, D.P.; Dooker, G.I.

1981-01-01

A neutron-absorbing article suitable for use in spent fuel racks is described. It comprises boron carbide particles, diluent particles, and a phenolic polymer cured to a continuous matrix. The diluent may be silicon carbide, graphite, amorphous carbon, alumina, or silica. The combined boron carbide-diluent phase contains no more than 2 percent B 2 O 3 , and the neutron-absorbing article contains from 20 to 40 percent phenol resin. The ratio of boron carbide to diluent particles is in the range 1:9 to 9:1

Mechanical shock absorber

International Nuclear Information System (INIS)

Vrillon, Bernard.

1973-01-01

The mechanical shock absorber described is made of a constant thickness plate pierced with circular holes regularly distributed in such a manner that for all the directions along which the strain is applied during the shock, the same section of the substance forming the plate is achieved. The shock absorber is made in a metal standing up to extensive deformation before breaking, selected from a group comprising mild steels and austenitic stainless steels. This apparatus is used for handling pots of fast neutron reactor fuel elements [fr

Low Absorbance Measurements

Science.gov (United States)

Harris, T. D.; Williams, A. M.

1983-10-01

The application of low absorption measurements to dilute solute determination requires specific instrumental characteristics. The use of laser intracavity absorption and thermal lens calorimetry to measure concentration is shown. The specific operating parameters that determine sensitivity are delineated along with the limits different measurement strategies impose. Finally areas of improvement in components that would result in improve sensitivity, accuracy, and reliability are discussed. During the past decade, a large number of methods have been developed for measuring the light absorbed by transparent materials. These include measurements on gases, liquids, and solids. The activity has been prompted by a variety of applications and a similar variety of disciplines. In Table 1 some representative examples of these methods is shown along with their published detection limits.1 It is clear that extraordinarily small absorbances can be measured. Most of the methods can be conveniently divided into two groups. These groups are those that measure the transmission of the sample and those that measure the light absorbed by the sample. The light absorbed methods are calorimetric in character. The advantages and disadvantages of each method varies depending on the principal application for which they were developed. The most prevalent motivation has been to characterize the bulk optical properties of transparent materials. Two examples are the development of extremely transparent glasses for use as fiber optic materials and the development of substrates for high power laser operation.

Structure-driven turbulence in ``No man's Land''

Science.gov (United States)

Kosuga, Yusuke; Diamond, Patrick

2012-10-01

Structures are often observed in many physical systems. In tokamaks, for example, such structures are observed as density blobs and holes. Such density blobs and holes are generated at the tokamak edge, where strong gradient perturbations generate an outgoing blob and an incoming hole. Since density holes can propagate from the edge to the core, such structures may play an important role in understanding the phenomenology of the edge-core coupling region, so-called ``No Man's Land.'' In this work, we discuss the dynamics of such structures in real space. In particular, we consider the dynamics of density blobs and holes in the Hasegawa-Wakatani system. Specific questions addressed here include: i) how these structures extract free energy and enhance transport? how different is the relaxation driven by such structures from that driven by linear drift waves? ii) how these structures interact with shear flows? In particular, how these structures interact with a shear layer, which can absorb structures resonantly? iii) how can we calculate the coupled evolution of structures and shear flows? Implications for edge-core coupling problem are discussed as well.

Average [O II] nebular emission associated with Mg II absorbers: dependence on Fe II absorption

Science.gov (United States)

Joshi, Ravi; Srianand, Raghunathan; Petitjean, Patrick; Noterdaeme, Pasquier

2018-05-01

We investigate the effect of Fe II equivalent width (W2600) and fibre size on the average luminosity of [O II] λλ3727, 3729 nebular emission associated with Mg II absorbers (at 0.55 ≤ z ≤ 1.3) in the composite spectra of quasars obtained with 3 and 2 arcsec fibres in the Sloan Digital Sky Survey. We confirm the presence of strong correlations between [O II] luminosity (L_{[O II]}) and equivalent width (W2796) and redshift of Mg II absorbers. However, we show L_{[O II]} and average luminosity surface density suffer from fibre size effects. More importantly, for a given fibre size, the average L_{[O II]} strongly depends on the equivalent width of Fe II absorption lines and found to be higher for Mg II absorbers with R ≡W2600/W2796 ≥ 0.5. In fact, we show the observed strong correlations of L_{[O II]} with W2796 and z of Mg II absorbers are mainly driven by such systems. Direct [O II] detections also confirm the link between L_{[O II]} and R. Therefore, one has to pay attention to the fibre losses and dependence of redshift evolution of Mg II absorbers on W2600 before using them as a luminosity unbiased probe of global star formation rate density. We show that the [O II] nebular emission detected in the stacked spectrum is not dominated by few direct detections (i.e. detections ≥3σ significant level). On an average, the systems with R ≥ 0.5 and W2796 ≥ 2 Å are more reddened, showing colour excess E(B - V) ˜ 0.02, with respect to the systems with R < 0.5 and most likely trace the high H I column density systems.

Shock absorber in Ignalina NPP

International Nuclear Information System (INIS)

Bulavas, A.; Muralis, J.

1996-09-01

Theoretical calculation and experimental analysis of models of shock absorber in Ignalina NPP is presented. The results obtained from the investigation with model of shock absorber coincide with the theoretical calculation. (author). 2 figs., 3 refs

Liquid metal reactor absorber technology

International Nuclear Information System (INIS)

Pitner, A.L.

1990-10-01

The selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts. 3 refs., 3 figs

On the definition of absorbed dose

International Nuclear Information System (INIS)

Grusell, Erik

2015-01-01

Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before. - Highlights: • A stringent definition of absorbed dose is given. • This requires the definition of an irradiation and a suitable probability space. • A stringent definition is important for an understanding of the concept absorbed dose

On the origin of highly ionized X-ray absorbers detected in the galactic X-ray binaries

International Nuclear Information System (INIS)

Luo, Yang; Fang, Taotao

2014-01-01

X-ray observations of the Galactic X-ray binaries (XRBs) revealed numerous highly ionized metal absorption lines. However, it is unclear whether such lines are produced by the hot interstellar medium (ISM) or the circumstellar medium intrinsic to the binaries. Here we present a Chandra X-ray absorption line study of 28 observations of 12 XRBs, with a focus on the Ne IX and Fe XVII lines. We report the first detections of these lines in a significant amount of observations. We do not find a significant dependence of the line equivalent width on the distance of the XRBs, but we do see a weak dependence on the source X-ray luminosity. We also find 2 out of 12 selected targets show strong temporal variation of the Ne IX absorbers. While the line ratio between the two ion species suggests a temperature consistent with the previous predictions of the ISM, comparing with two theoretical models of the ISM shows the observed column densities are significantly higher than predictions. On the other hand, photoionization by the XRBs provides a reasonably good fit to the data. Our findings suggest that a significant fraction of these X-ray absorbers may originate in the hot gas intrinsic to the XRBs, and that the ISM makes small, if not negligible, contribution. We briefly discuss the implications to the study of the Milky Way hot gas content.

Microcontroller-driven fluid-injection system for atomic force microscopy.

Science.gov (United States)

Kasas, S; Alonso, L; Jacquet, P; Adamcik, J; Haeberli, C; Dietler, G

2010-01-01

We present a programmable microcontroller-driven injection system for the exchange of imaging medium during atomic force microscopy. Using this low-noise system, high-resolution imaging can be performed during this process of injection without disturbance. This latter circumstance was exemplified by the online imaging of conformational changes in DNA molecules during the injection of anticancer drug into the fluid chamber.

Molecular cloud formation by gravitational instabilities in a clumpy interstellar medium

International Nuclear Information System (INIS)

Elmegreen, B.G.

1989-01-01

A dispersion relation is derived for gravitational instabilities in a medium with cloud collisional cooling, using a time-dependent energy equation instead of the adiabatic equation of state. The instability extends to much smaller length scales than in the conventional Jeans analysis, and, in regions temporarily without cloud stirring, it has a large growth rate down to the cloud collision mean free path. These results suggests that gravitational instabilities in a variety of environments, such as galactic density wave shocks, swept-up shells, and extended, quiescent regions of the interstellar medium, can form molecular clouds with masses much less than the conventional Jeans mass, e.g., from 100 to 10 million solar masses for the ambient medium, and they can do this even when the unperturbed velocity dispersion remains high. Similar processes operating inside existing clouds might promote gravitationally driven fragmentation. 29 refs

Design Considerations for an MEBT Chopper Absorber of 2.1 MeV H- at the Project X Injector Experiment at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Baffes, C.; Awida, M.; Chen, A.; Eidelman, Y.; Lebedev, V.; Prost, L.; Shemyakin, A.; Solyak, N.; Yakovlev, V.; /Fermilab

2012-05-14

The Project X Injector Experiment (PIXIE) will be a prototype of the Project X front end that will be used to validate the design concept and decrease technical risks. One of the most challenging components of PIXIE is the wide-band chopping system of the Medium Energy Beam Transport (MEBT) section, which will form an arbitrary bunch pattern from the initially CW 162.5 MHz 5mA beam. The present scenario assumes diverting 80% of the beam to an absorber to provide a beam with the average current of 1mA to SRF linac. This absorber must withstand a high level of energy deposition and high ion fluence, while being positioned in proximity of the superconductive cavities. This paper discusses design considerations for the absorber. Thermal and mechanical analyses of a conceptual design are presented, and future plans for the fabrication and testing of a prototype are described.

Effect of medium replenishment or composition on [3H] thymidine incorporation in uv-irradiated CHO-K1 cells

International Nuclear Information System (INIS)

Newman, C.N.; Miller, J.H.

1985-03-01

Because culture medium contains uv-absorbing material, it is usually removed just before uv-irradiation of tissue culture monolayers. However, medium removal and replenishment with fresh medium alone (sham-irradiation) causes up to a 10-fold reduction in the rate of [ 3 H]TdR incorporation in CHO-K1 cells which persists for several hours. This reduction, which is much smaller ( 3 H]TdR pulse-label in conditioned (spent) and in fresh medium; TdR in the former is converted by cells to thymine. When responses of uv-irradiated cells are normalized to responses of corresponding sham-irradiated cultures, considerable variation is observed in replicate experiments because fresh medium appears to induce transient metabolic imbalances in irradiated cells which are not readily controlled. This problem can, in part, be circumvented by replenishing treated cultures with the original spent medium; however, the presence of CdR in the growth medium still causes an anomalous 2-3-fold greater uv-induced reduction in [ 3 H]TdR incorporation than is observed in the absence of CdR. 17 refs., 3 figs., 1 tab

Burnable neutron absorbers

International Nuclear Information System (INIS)

Radford, K.C.; Carlson, W.G.

1985-01-01

This patent deals with the fabrication of pellets for neutron absorber rods. Such a pellet includes a matrix of a refractory material which may be aluminum or zirconium oxide, and a burnable poison distributed throughout the matrix. The neutron absorber material may consist of one or more elements or compounds of the metals boron, gadolinium, samarium, cadmium, europium, hafnium, dysprosium and indium. The method of fabricating pellets of these materials outlined in this patent is designed to produce pores or voids in the pellets that can be used to take up the expansion of the burnable poison and to absorb the helium gas generated. In the practice of this invention a slurry of Al 2 O 3 is produced. A hard binder is added and the slurry and binder are spray dried. This powder is mixed with dry B 4 C powder, forming a homogeneous mixture. This mixture is pressed into green tubes which are then sintered. During sintering the binder volatilizes leaving a ceramic with nearly spherical high-density regions of

Epileptogenesis in organotypic hippocampal cultures has limited dependence on culture medium composition.

Directory of Open Access Journals (Sweden)

Jing Liu

Full Text Available Rodent organotypic hippocampal cultures spontaneously develop epileptiform activity after approximately 2 weeks in vitro and are increasingly used as a model of chronic post-traumatic epilepsy. However, organotypic cultures are maintained in an artificial environment (culture medium, which contains electrolytes, glucose, amino acids and other components that are not present at the same concentrations in cerebrospinal fluid (CSF. Therefore, it is possible that epileptogenesis in organotypic cultures is driven by these components. We examined the influence of medium composition on epileptogenesis. Epileptogenesis was evaluated by measurements of lactate and lactate dehydrogenase (LDH levels (biomarkers of ictal activity and cell death, respectively in spent culture media, immunohistochemistry and automated 3-D cell counts, and extracellular recordings from CA3 regions. Changes in culture medium components moderately influenced lactate and LDH levels as well as electrographic seizure burden and cell death. However, epileptogenesis occurred in any culture medium that was capable of supporting neural survival. We conclude that medium composition is unlikely to be the cause of epileptogenesis in the organotypic hippocampal culture model of chronic post-traumatic epilepsy.

Epileptogenesis in organotypic hippocampal cultures has limited dependence on culture medium composition.

Science.gov (United States)

Liu, Jing; Saponjian, Yero; Mahoney, Mark M; Staley, Kevin J; Berdichevsky, Yevgeny

2017-01-01

Rodent organotypic hippocampal cultures spontaneously develop epileptiform activity after approximately 2 weeks in vitro and are increasingly used as a model of chronic post-traumatic epilepsy. However, organotypic cultures are maintained in an artificial environment (culture medium), which contains electrolytes, glucose, amino acids and other components that are not present at the same concentrations in cerebrospinal fluid (CSF). Therefore, it is possible that epileptogenesis in organotypic cultures is driven by these components. We examined the influence of medium composition on epileptogenesis. Epileptogenesis was evaluated by measurements of lactate and lactate dehydrogenase (LDH) levels (biomarkers of ictal activity and cell death, respectively) in spent culture media, immunohistochemistry and automated 3-D cell counts, and extracellular recordings from CA3 regions. Changes in culture medium components moderately influenced lactate and LDH levels as well as electrographic seizure burden and cell death. However, epileptogenesis occurred in any culture medium that was capable of supporting neural survival. We conclude that medium composition is unlikely to be the cause of epileptogenesis in the organotypic hippocampal culture model of chronic post-traumatic epilepsy.

Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

Science.gov (United States)

Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

1989-01-01

The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

Effect of. gamma. -radiation of /sup 60/Co on bacteria Sphaerotilus natans in nutrient medium containing calcium and lithium

Energy Technology Data Exchange (ETDEWEB)

Leonowicz-Babiak, K; Radziwolska, E; Widera, M

1980-01-01

The effect of ..gamma..-radiation of /sup 60/Co on an increase in dry matter of the polysaprobic zone bacteria Sphaerotilus natans was studied. Bacterial growth depended on the radiation dose absorbed. With a rise of the dose, the bacterial dry matter usually decreased. This relationship was not observed at a radiation dose of 72 krad. In the presence of calcium in the medium, the bacterial dry matter increased. An addition of lithium salt to the medium failed to increase the bacterial dry matter.

XMM-Newton Spectroscopy of the Accretion-driven Millisecond X-Ray Pulsar XTE J1751-305 in Outburst

NARCIS (Netherlands)

Miller, J. M.; Wijnands, R.; Méndez, M.; Kendziorra, E.; Tiengo, A.; van der Klis, M.; Chakrabarty, D.; Gaensler, B. M.; Lewin, W. H. G.

2003-01-01

We present an analysis of the first high-resolution spectra measured from an accretion-driven millisecond X-ray pulsar in outburst. We observed XTE J1751-305 with XMM-Newton on 2002 April 7 for approximately 35 ks. Using a simple absorbed blackbody plus power-law model, we measure an unabsorbed flux

Grid Filter Design for a Multi-Megawatt Medium-Voltage Voltage Source Inverter

DEFF Research Database (Denmark)

Rockhill, A.A.; Liserre, Marco; Teodorescu, Remus

2011-01-01

This paper describes the design procedure and performance of an LCL grid filter for a medium-voltage neutral point clamped (NPC) converter to be adopted for a multimegawatt wind turbine. The unique filter design challenges in this application are driven by a combination of the medium voltage...... converter, a limited allowable switching frequency, component physical size and weight concerns, and the stringent limits for allowable injected current harmonics. Traditional design procedures of grid filters for lower power and higher switching frequency converters are not valid for a multi......-megawatt filter connecting a medium-voltage converter switching at low frequency to the electric grid. This paper demonstrates a frequency domain model based approach to determine the optimum filter parameters that provide the necessary performance under all operating conditions given the necessary design...

Dynamic testing of airplane shock-absorbing struts

Science.gov (United States)

Langer, P; Thome, W

1932-01-01

Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

Liquid absorber experiments in ZED-2

International Nuclear Information System (INIS)

McDonnell, F.N.

1975-07-01

A set of liquid absorber experiments was performed in ZED-2 to provide data with which to test the adequacy of calculational methods for zone controller and refuelling studies associated with advanced reactor concepts. The absorber consisted of a full length aluminum tube, containing either i)H 2 O, ii)H 2 O + boron (2.5 mg/ml) or iii)H 2 O + boron (8.0 mg/ml). The tube was suspended vertically at interstitial or in-channel locations. A U-tube absorber was also simulated using two absorber tubes with appropriate spacers. Experiments were carried out at two different square lattice pitches, 22.86 and 27.94 cm. Measurements were made of the reactivity effects of the absorbers and, in some cases, of the detailed flux distribution near the perturbation. The results from one calculational method, the source-sink approach, were compared with the data from selected experiments. (author)

A chiral microwave absorbing absorbent of Fe–CoNiP coated on spirulina

Energy Technology Data Exchange (ETDEWEB)

Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yuan, Liming [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Zhang, Deyuan [School of Mechanical Engineering and Automation, Beihang University, Beijing, 100191 (China)

2015-11-15

A chiral bio-absorbent of Fe–CoNiP coated on the spirulina was fabricated by the electroless and chemical vapor decomposition. The scanning electron microscopy (SEM) was used to evaluate the spirulina cells particle morphology. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The permittivity and permeability was measured by a vector network analyzer in frequency 8–18 GHz, and the reflection loss (RL) was calculated. The results showed the carbonyl iron particles (CIPs) and CoNiP were bonded to the spirulina surface, the permittivity and permeability could be enlarged as Fe films coated on the particles compared with the CoNiP spirulina, it was attributed to the excellent electromagnetic property of CIPs. The chiral Fe–CoNiP composites had a better absorbing property at 8–18 GHz than the CoNiP spirulina composite, the RL was −16.26 dB at 10.48 GHz, the absorbing band was 9.5–11.5 GHz of RL less than −10 dB, which indicated the Fe–CoNiP spirulina could be an effective absorbent used in 8–18 GHz. - Highlights: • Absorbers filled with Fe–CoNiP coating on the spirulina were fabricated. • The permittivity and permeability increased as CIPs coated. • The Fe material enhanced the electromagnetic property. • The spirulina coated Fe–CoNiP was effective in 8–18 GHz.

Absorber rod drive for nuclear reactors

International Nuclear Information System (INIS)

Acher, H.

1985-01-01

The invention concerns a further addition to the invention of DE 33 42 830 A1. The free contact of the hollow piston with the nut due to hydraulic pressure is replaced by a hydraulic or spring attachment. The pressure system required to produce the hydraulic pressure is therefore omitted, and the electrical power required for driving the pump or the mass flow is also omitted. The absorber rod slotted along its longitudinal axis is replaced by an absorber rod, in the longitudinal axis of which a hollow piston is connected together with the absorber rod. This makes the absorber rod more stable, and assembly is simplified. (orig./HP) [de

Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

International Nuclear Information System (INIS)

Kumar, Arvind; Verma, G.S.P.

1975-01-01

Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber. (author)

Low-frequency observations of Galactic supernova remnants and the distribution of low-density ionized gas in the interstellar medium

International Nuclear Information System (INIS)

Kassim, N.E.

1989-01-01

New long-wavelength observations of Galactic SNRs at 30.9 and 57.5 MHz are used to derive detailed low-frequency radio spectra for 32 SNRs. Of these, about two-thirds show turnovers at low frequencies, implying the presence of a widespread, but inhomogeneous, ionized absorbing medium along the lines of sight. These observations are combined with other low-frequency data to derive free-free optical depths toward 457 SNRs and to constrain the physical properties of the ionized gas responsible for the absorption. These optical depths are consistent with the expected absorbing properties of extended H II region envelopes. 43 refs

Comparative studies of parameters based on the most probable versus an approximate linear extrapolation distance estimates for circular cylindrical absorbing rod

International Nuclear Information System (INIS)

Wassef, W.A.

1982-01-01

Estimates and techniques that are valid to calculate the linear extrapolation distance for an infinitely long circular cylindrical absorbing region are reviewed. Two estimates, in particular, are put into consideration, that is the most probable and the value resulting from an approximate technique based on matching the integral transport equation inside the absorber with the diffusion approximation in the surrounding infinite scattering medium. Consequently, the effective diffusion parameters and the blackness of the cylinder are derived and subjected to comparative studies. A computer code is set up to calculate and compare the different parameters, which is useful in reactor analysis and serves to establish a beneficial estimates that are amenable to direct application to reactor design codes

Study of neutron absorbing microspheres in research reactors - Neutronic analyse

International Nuclear Information System (INIS)

Gana Watkins, Ignacio A.; Prado, Miguel O.; Mazufri, Claudio; Tunon, Juan M

2012-01-01

Now-a-days, it is increasingly common for nuclear power plants, as well as research reactors, to be designed and built with an alternative safety system aside from control rods. The acids and/or salts in solution injection systems is most frequently used. However, these systems present several implementation and operation problems due to the physical and chemical properties of the used compounds. After analyzing these drawbacks, we developed a new alternative safety system that contains the absorbing element isolated from the aqueous medium. In this context, it's proposed the use of aluminum borosilicate microspheres. The current paper presents erosion wear experiments to determine under which conditions microspheres can be considered as a potential component of a secondary shut down system in a nuclear facility (author)

The causal effect of board size in the performance of small and medium-sized firms

DEFF Research Database (Denmark)

Bennedsen, Morten; Kongsted, Hans Christian; Meisner Nielsen, Kasper

2008-01-01

correlation between family size and board size and show this correlation to be driven by firms where the CEO's relatives serve on the board. Second, we find empirical evidence of a small adverse board size effect driven by the minority of small and medium-sized firms that are characterized by having......Empirical studies of large publicly traded firms have shown a robust negative relationship between board size and firm performance. The evidence on small and medium-sized firms is less clear; we show that existing work has been incomplete in analyzing the causal relationship due to weak...... identification strategies. Using a rich data set of almost 7000 closely held corporations we provide a causal analysis of board size effects on firm performance: We use a novel instrument given by the number of children of the chief executive officer (CEO) of the firms. First, we find a strong positive...

Toward a Singleton Undergraduate Computer Graphics Course in Small and Medium-Sized Colleges

Science.gov (United States)

Shesh, Amit

2013-01-01

This article discusses the evolution of a single undergraduate computer graphics course over five semesters, driven by a primary question: if one could offer only one undergraduate course in graphics, what would it include? This constraint is relevant to many small and medium-sized colleges that lack resources, adequate expertise, and enrollment…

THE SURPRISINGLY CONSTANT STRENGTH OF O VI ABSORBERS OVER COSMIC TIME

International Nuclear Information System (INIS)

Fox, Andrew J.

2011-01-01

O VI absorption is observed in a wide range of astrophysical environments, including the local interstellar medium, the disk and halo of the Milky Way, high-velocity clouds, the Magellanic Clouds, starburst galaxies, the intergalactic medium (IGM), damped Lyα systems, and gamma-ray-burst host galaxies. Here, a new compilation of 775 O VI absorbers drawn from the literature is presented, all observed at high resolution (instrumental FWHM ≤ 20 km s -1 ) and covering the redshift range z = 0-3. In galactic environments [log N(H I) ∼> 20], the mean O VI column density is shown to be insensitive to metallicity, taking a value log N(O VI) ∼ 14.5 for galaxies covering the range -1.6 ∼ 4 K) clouds and hot (∼10 6 K) plasma, although many such layers would have to be intersected by a typical galaxy-halo sight line to build up the characteristic galactic N(O VI). The alternative, widely used model of single-phase photoionization for intergalactic O VI is ruled out by kinematic evidence in the majority of IGM O VI components at low and high redshift.

A novel energy absorber based on magnetorheological gel

Science.gov (United States)

Pang, Haoming; Xuan, Shouhu; Sun, Chuanlin; Gong, Xinglong

2017-10-01

In this work, a novel magnetorheological energy absorber (MREA) was designed by using magnetorheological gel (MRG) as the damping medium. The proposed MREA had tunable piston gap distances and variable inner magnetic flux density distribution. The piston gap distance could be varied from 7-2 mm and the magnetic flux density at the gap increased from 120-860 mT, respectively. Under both low velocity compression and high speed impact, the damping could be divided into three parts. In the impact test, the velocity of a drop hammer could be reduced from to 3.4-0 m s-1 within a very short time (13 ms) and distance (17 mm). The maximum damping force of the MREA reached to as high as 8 kN. The damping force could also be adjusted by changing the current input. Under a 2 A current, the energy absorption ratio increased about 23% (from 4.13-5.07 J mm-1).

Multiband Negative Permittivity Metamaterials and Absorbers

Directory of Open Access Journals (Sweden)

Yiran Tian

2013-01-01

Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

Absorber materials in CANDU PHWR's

International Nuclear Information System (INIS)

Price, E.G.; Boss, C.R.; Novak, W.Z.; Fong, R.W.L.

1995-03-01

In a CANDU reactor the fuel channels are arranged on a square lattice in a calandria filled with heavy water moderator. This arrangement allows five types of tubular neutron absorber devices to be located in a relatively benign environment of low pressure, low temperature heavy water between neighbouring rows of columns of fuel channels. This paper will describe the roles of the devices and outline the design requirements of the absorber component from a reactor physics viewpoint. Nuclear heating and activation problems associated with the different absorbers will be briefly discussed. The design and manufacture of the devices will be also discussed. The control rod absorbers and shut off materials are cadmium and stainless steel. In the tubular arrangement, the cadmium is sandwiched between stainless steel tubes. This type of device has functioned well, but there is now concern over the availability and expense of cadmium which is used in two types of CANDU control devices. There are also concerns about the toxicity of cadmium during the fabrication of the absorbers. These concerns are prompting AECL to study alternatives. To minimize design changes, pure boron-10 alloyed in stainless steel is a favoured option. Work is underway to confirm the suitability of the boron-loaded steel and identify other encapsulated absorber materials for practical application. Because the reactivity devices or their guide tubes span the calandria vessel, the long slender components must be sufficiently rigid to resist operational vibration and also be seismically stable. Some of these components are made of Zircaloy to minimize neutron absorption. Slow irradiation growth and creep can reduce the spring tension, and periodic adjustments to the springs are required. Experience with the control absorber devices has generally been good. In one instance liquid zone controllers had a problem of vibration induced fretting but a designed back-fit resolved the problem. (author). 3 refs., 1

TPX/TFTR Neutral Beam energy absorbers

International Nuclear Information System (INIS)

Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

1993-01-01

The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET

Two-dimensional QR-coded metamaterial absorber

Science.gov (United States)

Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Zhang, Jieqiu; Qu, Shaobo

2016-01-01

In this paper, the design of metamaterial absorbers is proposed based on QR coding and topology optimization. Such absorbers look like QR codes and can be recognized by decoding softwares as well as mobile phones. To verify the design, two lightweight wideband absorbers are designed, which can achieve wideband absorption above 90 % in 6.68-19.30 and 7.00-19.70 GHz, respectively. More importantly, polarization-independent absorption over 90 % can be maintained under incident angle within 55°. The QR code absorber not only can achieve wideband absorption, but also can carry information such as texts and Web sites. They are of important values in applications such identification and electromagnetic protection.

Recycling Pig Slurry Solid Fraction Compost as a Sound Absorber

Directory of Open Access Journals (Sweden)

Niccolò Pampuro

2018-01-01

Full Text Available The aim of this investigation was to determine the physical and acoustical properties of compacts made from composted pig slurry solid fraction (SF in order to assess the potential to recycle this agricultural waste as a sound absorber. The compacts were obtained by compression. The physical parameters investigated were bulk density, durability, and particle size distribution. The acoustical features of the compacts were studied with an impedance tube device in order to verify the acoustic absorption coefficient. Two composts were prepared: pig SF compost without a bulking agent (SSFC and pig SF compost with wood chips as a bulking agent (WCC. The study’s results indicated that compost particles dimension played a key role in the physical and acoustical properties of the compacts: the smaller the particles, the higher the physical and acoustical properties of the compacts. The densification process increased the bulk density of the investigated composts up to 690 kg m−3 for SSFC and 660 kg m−3 for WWC, with, respectively, medium (77.9% and low (66.5% durability. The addition of woody bulking agent significantly reduced the absorption coefficient: the best results, in terms of potential use as a sound absorber, were observed for compacts made from composted pig slurry solid fraction without the addition of wood chips.

Measuring and slowing decoherence in Electromagnetically induced transparency medium

International Nuclear Information System (INIS)

Shuker, M.; Firstenberg, O.; Sagi, Y.; Ben-Kish, A.; Fisher, A.; Ron, A.; Davidson, N.

2005-01-01

Full Text:Electromagnetically induced transparency is a unique light-matter interaction that exhibits extremely narrow-band spectroscopic features along with low absorption. Recent interest in this phenomenon is driven by its possible applications in quantum information (slow light, storage of light), atomic clocks and precise magnetometers. The Electromagnetically induced transparency phenomenon takes place when an atomic ensemble is driven to a coherent superposition of its ground state sub-levels by two phase-coherent radiation fields. A key parameter of the Electromagnetically induced transparency medium, that limits its applicability, is the coherence lifetime of this superposition (decoherence rate). We have developed a simple technique to measure decay rates within the ground state of an atomic ensemble, and specifically the decoherence rate of the Electromagnetically induced transparency coherent superposition. Detailed measurements were performed in a Rubidium vapor cell at 60 - 80 with 30 Torr of Neon buffer gas. We have found that the Electromagnetically induced transparency decoherence is dominated by spin-exchange collisions between Rubidium atoms. We discuss the sensitivity of various quantum states of the atomic ensemble to spin exchange decoherence, and find a set of quantum states that minimize this effect. Finally, we demonstrate a unique quantum state which is both insensitive to spin exchange decoherence and constitutes an Electromagnetically induced transparency state of the medium

Estimation of Absorbed Dose in Occlusal Radiography

International Nuclear Information System (INIS)

Yoo, Young Ah; Choi, Karp Shick; Lee, Sang Han

1990-01-01

The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-210 Head and Neck Section R, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70 Kvp and 15 mA, 1/4 second (8 inch cone ) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In Mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

Photoelectron antibunching and absorber theory

International Nuclear Information System (INIS)

Pegg, D.T.

1980-01-01

The recently detected photoelectron antibunching effect is considered to be evidence for the quantised electromagnetic field, i.e. for the existence of photons. Direct-action quantum absorber theory, on the other hand, has been developed on the basis that the quantised field is illusory, with quantisation being required only for atoms. In this paper it is shown that photoelectron antibunching is readily explicable in terms of absorber theory and in fact is directly attributable to the quantum nature of the emitting and detecting atoms alone. The physical nature of the reduction of the wavepacket associated with the detection process is briefly discussed in terms of absorber theory. (author)

An omnidirectional electromagnetic absorber made of metamaterials

International Nuclear Information System (INIS)

Cheng Qiang; Cui Tiejun; Jiang Weixiang; Cai Bengeng

2010-01-01

In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.

Additive manufacturing of RF absorbers

Science.gov (United States)

Mills, Matthew S.

The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

Preparation of super absorbent by irradiation polymerization

International Nuclear Information System (INIS)

Hua Fengjun; Tan Chunhong; Qian Mengping

1995-01-01

A kind of absorbent is prepared by gamma-rays irradiated by reversed-phase suspension polymerization. Drying particles have 1400 (g/g) absorbency in de-ionic water. Effects of reactive conditions, e.g.: dose-rate, dose, monomer concentration, degree of monomer neutralization and crosslinking agents on absorbency in de-ionic water are discussed. The cause of absorbing de-ionic water by polymer is related to its network structure and ionic equilibrium in particle. Accordingly, a suit reactive condition is chosen for preparation of hydro gel spheres

Frequency Tuning of Vibration Absorber Using Topology Optimization

Science.gov (United States)

Harel, Swapnil Subhash

A tuned mass absorber is a system for reducing the amplitude in one oscillator by coupling it to a second oscillator. If tuned correctly, the maximum amplitude of the first oscillator in response to a periodic driver will be lowered, and much of the vibration will be 'transferred' to the second oscillator. The tuned vibration absorber (TVA) has been utilized for vibration control purposes in many sectors of Civil/Automotive/Aerospace Engineering for many decades since its inception. Time and again we come across a situation in which a vibratory system is required to run near resonance. In the past, approaches have been made to design such auxiliary spring mass tuned absorbers for the safety of the structures. This research focuses on the development and optimization of continuously tuned mass absorbers as a substitute to the discretely tuned mass absorbers (spring- mass system). After conducting the study of structural behavior, the boundary condition and frequency to which the absorber is to be tuned are determined. The Modal analysis approach is used to determine mode shapes and frequencies. The absorber is designed and optimized using the topology optimization tool, which simultaneously designs, optimizes and tunes the absorber to the desired frequency. The tuned, optimized absorber, after post processing, is attached to the target structure. The number of the absorbers are increased to amplify bandwidth and thereby upgrade the safety of structure for a wide range of frequency. The frequency response analysis is carried out using various combinations of structure and number of absorber cell.

COMPARISON OF ABSORBABLE EXTRA LONG TERM POLY HYDROXY BUTYRATE SUTURE VS NON ABSORBABLE (POLYPROPYLENE SUTURE FOR ABDOMINAL WALL CLOSURE

Directory of Open Access Journals (Sweden)

Mallikarjun

2015-07-01

Full Text Available PURPOSE: The aim of study is to compare Continuous technique with non - absorbable sutures, Interrupted technique with non - absorbable sutures and Continuous technique with slowly absorbable sutures Focusing mainly on incidence of incisional hernias, burst abdomen, wound infections, chronic wound pain, suture sinus, stitch granuloma, time for rectus closure. METHODOLOGY : Study was conducted for a period of one year on 271 randomized patients with primary elective midline laparotomy in our hospital . patients are divided into group I includes 102 patients with continuous technique using non absorbable polypropylene, group II includes 91 patients with interrupted technique using non absorbable polypropylene and group III includes 78 patients with continuous slowly absorbable polyhydroxybutyrate. RESULTS: No significant difference observed in incidence of wound infections and burst abdomen in all the 3 groups but relatively higher incidence of wound infections in noted our hospital. Incidence of stich granuloma suture sinus and chronic wound pain is more with interrupted technique than continuous technique and are more with non - absor bable suture material. CONCLUSION: Incidence of incisional hernias, suture complications like suture sinus, stitch granuloma can be more effectively reduced with slowly absorbable continuous sutures.

Authoring Data-Driven Videos with DataClips.

Science.gov (United States)

Amini, Fereshteh; Riche, Nathalie Henry; Lee, Bongshin; Monroy-Hernandez, Andres; Irani, Pourang

2017-01-01

Data videos, or short data-driven motion graphics, are an increasingly popular medium for storytelling. However, creating data videos is difficult as it involves pulling together a unique combination of skills. We introduce DataClips, an authoring tool aimed at lowering the barriers to crafting data videos. DataClips allows non-experts to assemble data-driven "clips" together to form longer sequences. We constructed the library of data clips by analyzing the composition of over 70 data videos produced by reputable sources such as The New York Times and The Guardian. We demonstrate that DataClips can reproduce over 90% of our data videos corpus. We also report on a qualitative study comparing the authoring process and outcome achieved by (1) non-experts using DataClips, and (2) experts using Adobe Illustrator and After Effects to create data-driven clips. Results indicated that non-experts are able to learn and use DataClips with a short training period. In the span of one hour, they were able to produce more videos than experts using a professional editing tool, and their clips were rated similarly by an independent audience.

Shock absorber

International Nuclear Information System (INIS)

Nemeth, J.D.

1981-01-01

A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

21 CFR 880.5300 - Medical absorbent fiber.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device...

Optical quantitation of absorbers in variously shaped turbid media based on the microscopic Beer-Lambert law. A new approach to optical computerized tomography.

Science.gov (United States)

Tsuchiya, Y; Urakami, T

1998-02-09

To determine the concentrations of an absorber in variously shaped turbid media such as human tissue, we propose analytical expressions for diffuse re-emission in time and frequency domains, based on the microscopic Beer-Lambert law that holds true when we trace a zigzag photon path in the medium. Our expressions are implicit for the scattering properties, the volume shape, and the source-detector separation. We show that three observables are sufficient to determine the changes in the concentration and the absolute concentrations of an absorber in scattering media as long as the scattering property remains constant. The three observables are: the re-emission, the mean pathlength or group delay, and the extinction coefficient of the absorber. We also show that our equations can be extended to describe photon migration in nonuniform media. The validity of the predictions is confirmed by measuring a tissue-like phantom.

An experimental investigation of performance of a double pass solar air heater with thermal storage medium

Directory of Open Access Journals (Sweden)

Ali Hafiz Muhammad

2015-01-01

Full Text Available The performance of a double pass solar air heater was experimentally investigated using four different configurations. First configuration contained only absorber plate whereas copper tubes filled with thermal storage medium (paraffin wax were added on the absorber plate in the second configuration. Aluminum and steel rods as thermal enhancer were inserted in the middle of paraffin wax of each tube for configurations three and four respectively. Second configuration provided useful heat for about 1.5 hours after the sunset compared to first configuration. Configurations three and four provided useful heat for about 2 hours after the sunset. The maximum efficiency of about 96% was achieved using configuration three (i.e. using Aluminum rods in the middle of copper tubes filled with paraffin wax.

An ultra-broadband multilayered graphene absorber

KAUST Repository

Amin, Muhammad; Farhat, Mohamed; Bagci, Hakan

2013-01-01

An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon

High-efficiency ventilated metamaterial absorber at low frequency

Science.gov (United States)

Wu, Xiaoxiao; Au-Yeung, Ka Yan; Li, Xin; Roberts, Robert Christopher; Tian, Jingxuan; Hu, Chuandeng; Huang, Yingzhou; Wang, Shuxia; Yang, Zhiyu; Wen, Weijia

2018-03-01

We demonstrate a ventilated metamaterial absorber operating at low frequency (90%) has been achieved in both simulations and experiments. This high-efficiency absorption under the ventilation condition originates from the weak coupling of two identical split tube resonators constituting the absorber, which leads to the hybridization of the degenerate eigenmodes and breaks the absorption upper limit of 50% for conventional transmissive symmetric acoustic absorbers. The absorber can also be extended to an array and work in free space. The absorber should have potential applications in acoustic engineering where both noise reduction and ventilation are required.

Thermal Shielding Effects of a Damaged Shock Absorber and an Intact Shock Absorber

Energy Technology Data Exchange (ETDEWEB)

Bang, K. S.; Lee, J. C.; Kim, K. Y.; Seo, C. S.; Seo, K. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

In order to safely transport the radioactive waste arising from the hot test of an ACP(Advanced Spent Fuel Conditioning Process) a shipping package is required. Therefore, KAERI is developing a shipping package to transport the radioactive waste arising from the ACPF during a hot test. The regulatory requirements for a Type B package are specified in the Korea Most Act 2009-37, IAEA Safety Standard Series No. TS-R-1, and US 10 CFR Part. These regulatory guidelines classify the hot cell cask as a Type B package, and state that the Type B package for transporting radioactive materials should be able to withstand a test sequence consisting of a 9 m drop onto an unyielding surface, a 1 m drop onto a puncture bar, and a 30 minute fully engulfing fire. Greiner et al. investigated the thermal protection provided by shock absorbers by using the CAFE computer code. To evaluate the thermal shielding effect of the shock absorber, the thermal test was performed by using a 1/2 scale model with a shock absorber which was damaged by both a 9 m drop test and a 1 m puncture test. For the purpose of comparison, the thermal test was also carried out by using a 1/2 scale model with the intact shock absorber

On (m, n)-absorbing ideals of commutative rings

Indian Academy of Sciences (India)

with respect to various ring theoretic constructions and study (m, n)-absorbing ideals in several commutative rings. For example, in a Bézout ring or a Boolean ring, an ideal is an (m, n)-absorbing ideal if and only if it is an n-absorbing ideal, and in an almost. Dedekind domain every (m, n)-absorbing ideal is a product of at ...

Solution of the transport problem for electrons generated by an accelerator in the three-dimensional space of an absorber

International Nuclear Information System (INIS)

Vinogradov, V.V.

1981-01-01

The purpose of the investigation is the development of the method for calculation of distribution function of particles in the medium irradiated by electron beams. The process of particle transport was considered for infinite isotropic medium under the condition that all the particles, are concentrated in the source at first. The obtained solution can be used for investigation of particle transport through the substance with account of geometry of electron beam, particle distribution by the beam cross section, energy and angular spectra. The suggested approach can be applied for the solution of transport problems in which geometry of irradiated surface, presence of the field in the absorber should be taken into account that is significant when using electron accelerators in applied purposes [ru

Risk and timing of clinical events according to diabetic status of patients treated with everolimus-eluting bioresorbable vascular scaffolds versus everolimus-eluting stent: 2-year results from a propensity score matched comparison of ABSORB EXTEND and SPIRIT trials.

Science.gov (United States)

Campos, Carlos M; Caixeta, Adriano; Franken, Marcelo; Bartorelli, Antonio L; Whitbourn, Robert J; Wu, Chiung-Jen; Li Paul Kao, Hsien; Rosli, Mohd Ali; Carrie, Didier; De Bruyne, Bernard; Stone, Gregg W; Serruys, Patrick W; Abizaid, Alexandre

2018-02-15

to compare the occurrence of clinical events in diabetics treated with the Absorb bioresorbable vascular scaffold (Absorb BVS; Abbott Vascular, Santa Clara, CA) versus everolimus-eluting metal stents (EES; XIENCE V; Abbott Vascular, Santa Clara, CA) BACKGROUND: There are limited data dedicated to clinical outcomes of diabetic patients treated with bioresorbable scaffolds (BRS) at 2-year horizon. The present study included 812 patients in the ABSORB EXTEND study in which a total of 215 diabetic patients were treated with Absorb BVS. In addition, 882 diabetic patients treated with EES in pooled data from the SPIRIT clinical program (SPIRIT II, SPIRIT III and SPIRIT IV trials) were used for comparison by applying propensity score matching using 29 different variables. The primary endpoint was ischemia driven major adverse cardiac events (ID-MACE), including cardiac death, myocardial infarction (MI), and ischemia driven target lesion revascularization (ID-TLR). After 2 years, the ID-MACE rate was 6.5% in the Absorb BVS vs. 8.9% in the Xience group (P = 0.40). There was no difference for MACE components or definite/probable device thrombosis (HR: 1.43 [0.24,8.58]; P = 0.69). The occurrence of MACE was not different for both diabetic status (insulin- and non-insulin-requiring diabetes) in all time points up to the 2-year follow-up for the Absorb and Xience groups. In this largest ever patient-level pooled comparison on the treatment of diabetic patients with BRS out to two years, individuals with diabetes treated with the Absorb BVS had a similar rate of MACE as compared with diabetics treated with the Xience EES. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The impact of the South African tax system on small and medium sized enterprises

OpenAIRE

2012-01-01

M.Comm. Since the April 1994 elections the issue of economic empowerment and growth have had a high priority on the agenda of the Government of National Unity of South Africa. Small and medium enterprises (SME's) represent an important vehicle to address the challenges of job creation, economic growth and equity in our country. Throughout the world one finds that SME's are playing a critical role in absorbing labour, penetrating new markets and generally expanding economies in creative and...

The Dispersion of Fast Radio Bursts from a Structured Intergalactic Medium at Redshifts z < 1.5

Science.gov (United States)

Shull, J. Michael; Danforth, Charles W.

2018-01-01

We analyze the sources of free electrons that produce the large dispersion measures, {DM}≈ 300{--}1600 (in units of cm‑3 pc), observed toward fast radio bursts (FRBs). Individual galaxies typically produce {DM}∼ 25{--}60 {{cm}}-3 {pc} from ionized gas in their disk, disk-halo interface, and circumgalactic medium. Toward an FRB source at redshift z, a homogeneous intergalactic medium (IGM) containing a fraction {f}{IGM} of cosmological baryons will produce {DM}=(935 {{cm}}-3 {pc}){f}{IGM} {h}70-1I(z), where I{(z)=(2/3{{{Ω }}}m)[\\{{{{Ω }}}m(1+z)}3+{{{Ω }}}{{Λ }}\\}{}1/2-1]. A structured IGM of photoionized Lyα absorbers in the cosmic web produces similar dispersion, modeled from the observed distribution, {f}b(N,z), of H I (Lyα-forest) absorbers in column density and redshift with ionization corrections and scaling relations from cosmological simulations. An analytic formula for DM(z) applied to observed FRB dispersions suggests that {z}{FRB}≈ 0.2{--}1.5 for an IGM containing a significant baryon fraction, {f}{IGM}=0.6+/- 0.1. Future surveys of the statistical distribution, DM(z), of FRBs identified with specific galaxies and redshifts can be used to calibrate the IGM baryon fraction and distribution of Lyα absorbers. Fluctuations in DM at the level ±10 cm‑3 pc will arise from filaments and voids in the cosmic web.

Design of a nonlinear torsional vibration absorber

Science.gov (United States)

Tahir, Ammaar Bin

Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

Attosecond control of electron beams at dielectric and absorbing membranes

Science.gov (United States)

Morimoto, Yuya; Baum, Peter

2018-03-01

Ultrashort electron pulses are crucial for time-resolved electron diffraction and microscopy of the fundamental light-matter interaction. In this work, we study experimentally and theoretically the generation and characterization of attosecond electron pulses by optical-field-driven compression and streaking at dielectric or absorbing interaction elements. The achievable acceleration and deflection gradient depends on the laser-electron angle, the laser's electric and magnetic field directions, and the foil orientation. Electric and magnetic fields have similar contributions to the final effect and both need to be considered. Experiments and theory agree well and reveal the optimum conditions for highly efficient, velocity-matched electron-field interactions in the longitudinal or transverse direction. We find that metallic membranes are optimum for light-electron control at mid-infrared or terahertz wavelengths, but dielectric membranes are excellent in the visible and near-infrared regimes and are therefore ideal for the formation of attosecond electron pulses.

An improved resonantly driven piezoelectric gas pump

International Nuclear Information System (INIS)

Wu, Yue; Liu, Yong; Liu, Jianfang; Jiao, Xiaoyang; Yang, Zhigang; Wang, Long

2013-01-01

Piezoelectric pumps have the potential to be used in a variety of applications, such as in air circulation and compression. However, piezoelectric membrane pumps do not have enough driving capacity, and the heat induced during the direct contact between the driving part and the gas medium cannot be dissipated smoothly. When the gas is blocked, the piezoelectric vibrator generates heat quickly, which may eventually lead to damage. Resonantly driven piezoelectric stack pumps have high performance but no price advantage. In this situation, a novel, resonantly driven piezoelectric gas pump with annular bimorph as the driver is presented. In the study, the working principle of the novel pump was analyzed, the vibration mechanics model was determined, and the displacement amplified theory was studied. The outcome indicates that the displacement amplification factor is related with the original displacement provided by the piezoelectric bimorph. In addition, the displacement amplification effect is related to the stiffness of the spring lamination, adjustment spring, and piezoelectric vibrator, as well as to the systematic damping factor and the driving frequency. The experimental prototypes of the proposed pump were designed, and the displacement amplification effect and gas output performance were measured. At 70 V of sinusoidal AC driving voltage, the improved pump amplified the piezoelectric vibrator displacement by 4.2 times, the maximum gas output flow rate reached 1685 ml/min, and the temperature of the bimorph remained normal after 2000 hours of operation when the gas medium was blocked.

Performance evaluation of CFRP-rubber shock absorbers

Science.gov (United States)

Lamanna, Giuseppe; Sepe, Raffaele

2014-05-01

In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers' safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

Performance evaluation of CFRP-rubber shock absorbers

Energy Technology Data Exchange (ETDEWEB)

Lamanna, Giuseppe, E-mail: giuseppe.lamanna@unina2.it; Sepe, Raffaele, E-mail: giuseppe.lamanna@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, via Roma, 29 - 81031 Aversa (Italy)

2014-05-15

In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers’ safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

Burnable absorber coated nuclear fuel

International Nuclear Information System (INIS)

Chubb, W.; Radford, K.C.; Parks, B.H.

1984-01-01

A nuclear fuel body which is at least partially covered by a burnable neutron absorber layer is provided with a hydrophobic overcoat generally covering the burnable absorber layer and bonded directly to it. In a method for providing a UO 2 fuel pellet with a zirconium diboride burnable poison layer, the fuel body is provided with an intermediate niobium layer. (author)

Precision test method by x-ray absorbent clay

International Nuclear Information System (INIS)

Nakadai, Toru; Matsukawa, Hideyuki; Sekita, Jun-ichiro; Murakoshi, Atsushi.

1982-01-01

In X-ray penetration photography of such as welds with reinforcing metal and castings of complex shape, the X-ray absorbent clay developed to eliminate various disadvantages of the conventional absorbents was further studied for better application. The results of the usage are as follows. Because the X-ray absorbent is clay, it is flexible in form, and gives good adhesion to test objects. In the welds and castings mentioned, it is effective for reducing the scattered ray, accordingly, it results in superior images. The following matters are described: contrast in radiographs, the required conditions for X-ray absorbents in general, the properties of the absorbent (absorption coefficient, consistency, density), improvement in radiographs by means of the X-ray absorbent clay (wall thickness compensation, masking, the application together with narrow-field irradiation photography). (Mori, K.)

An ultra-broadband multilayered graphene absorber

KAUST Repository

Amin, Muhammad

2013-01-01

An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

Energy Absorbing Effectiveness – Different Approaches

Directory of Open Access Journals (Sweden)

Kotełko Maria

2018-03-01

Full Text Available In the paper the study of different crashworthiness indicators used to evaluate energy absorbing effectiveness of thin-walled energy absorbers is presented. Several different indicators are used to assess an effectiveness of two types of absorbing structures, namely thin-walled prismatic column with flaws and thin-walled prismatic frustum (hollow or foam filled in both cases subjected to axial compressive impact load. The indicators are calculated for different materials and different geometrical parameters. The problem of selection of the most appropriate and general indicators is discussed.

Microwave absorbing property of a hybrid absorbent with carbonyl irons coating on the graphite

Energy Technology Data Exchange (ETDEWEB)

Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yan, Zhenqiang; Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

2015-11-30

Graphical abstract: The absorbing property could be enhanced as the CIPs coated on the graphite. - Highlights: • Absorbers filled with CIPs coating on the graphite was fabricated. • The permittivity and permeability increased as CIPs coated. • The CIP materials enhanced the electromagnetic property. • The graphite coated CIPs were effective in 2–18 GHz. - Abstract: The hybrid absorbent filled with carbonyl iron particles (CIPs) coating on the graphite was prepared using a chemical vapor decomposition (CVD) process. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2–18 GHz. The results showed that α-Fe appeared in the super-lattice diffraction peaks in XRD graph. The composites added CIPs coating on the graphite had a higher permittivity and imaginary permeability due to the superior microwave dielectric loss and magnetic loss of the CIPs. The reflection loss (RL) result showed that composites filled with 5 vol% Fe-graphite had an excellent absorbing property in the 2–18 GHz, the minimum RL was −25.14 dB at 6 mm and −26.52 dB at 8 mm, respectively.

Study of neutron absorbing microspheres in research reactors - Metal systems wear

International Nuclear Information System (INIS)

Gana Watkins, Ignacio A.; Silin, Nicolas; Prado, Miguel O.; Mazufri, Claudio

2012-01-01

Now-a-days, it is increasingly common for nuclear power plants, as well as research reactors, to be designed and built with an alternative safety system aside from control rods. The acids and/or salts in solution injection systems is most frequently used. However, these systems present several implementation and operation problems due to the physical and chemical properties of the used compounds. After analyzing these drawbacks, we developed a new alternative safety system that contains the absorbing element isolated from the aqueous medium. In this context, it's proposed the use of aluminum borosilicate microspheres. The current paper presents erosion wear experiments to determine under which conditions microspheres can be considered as a potential component of a secondary shut down system in a nuclear facility (author))

The cooling of confined ions driven by laser beams

International Nuclear Information System (INIS)

Reyna, L.G.

1993-01-01

We finalize the dynamics of confined ions driven by a quantized radiation field. The ions can absorb photons from an incident laser beam and relax back to the ground state by either induced emissions or spontaneous emissions. Here we assume that the absorption of photons is immediately followed by spontaneous emissions, resulting in single-level ions perturbed by the exchange of momentum with the radiation field. The probability distribution of the ions is calculated using singular expansions in the low noise asymptotic limit. The present calculations reproduce the quantum results in the limit of heavy particles in static traps, and the classical results of ions in radio-frequency confining wells

Adjustable Shock Absorbers

OpenAIRE

Adamiec, Radek

2012-01-01

Bakalářská práce obsahuje přehled používaných tlumičů osobních automobilů, závodních automobilů a motocyklů. Jsou zde popsány systémy t lumením, konstrukce tlumičů a vidlic používaných u motocyklů. Dále je zde přehled prvků používaných u podvozků automobilů. This bachelor´s thesis contains the survey of the shock absorbers of passenger cars, racing cars and motorcycles. Are described damping systems, the design used shock absorbers and forks for motorcycles. Then there is the list of the e...

Slow and Fast Light in an Electro-Absorber

DEFF Research Database (Denmark)

Öhman, Filip; Bermejo Ramirez, Andres; Sales, Salvador

2006-01-01

We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated.......We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated....

A contribution to the investigation of the heat load of shock absorbers of semi-active suspensions in motor vehicles

Directory of Open Access Journals (Sweden)

Miroslav D. Demić

2013-10-01

the given vehicle model  have been written using the "NEWEUL." software package. The data input has been done in accordance with the program requirements, and 24 coordinate systems (including inertial-OI1I2I3 global coordinate system have been used to define the dynamic vehicle model with seven degrees of freedom. Thermal load on the shock absorbers of the semi-active suspension system Due to the relative motion between sprunged and unsprunged masses, mechanical work in the absorbers is equivalent to the amount of heat Q, J. As the heat flux is of a random size, it was assessed as appropriate to calculate the average power (flux for each buffer separately, and the data are given in Table 1 Table 1 Medium heat flux during a movement of  20, s Medium flux, W Front left absorber Front right absorber Rear left absorber Rear right absorber Speed 30,m/s, Mass 100% 2.330434E-006   5.569178E-006 5.358273E-006 2.944404E-006 Speed  5, m/s Mass 100% 2.435122E-006   5.673833E-006 5.477176E-006 2.968751E-006 Mass 75%, Speed 5, m/s 2.431798E-006   4.518553E-006 4.263119E-006 2.748116E-006 For  illustration, Fig. 1 shows the work converted to heat amount in the  shock absorbers of the semi-active suspension system, for a vehicle speed of  5 m/s. The analysis of the heat amount data for a speed of 5 and 30, m/s,for an illustrative example of a speed of 5, m / s , given in Fig. 1 shows that the amount of heat production increases with the covered distance (time. If the vehicle speed increases, the amount of heat decreases. The example in  Fig. 2 shows the effect of the vehicle load on the heat amount generated in the semi-active suspension system absorbers. Namely, the figure shows mechanical work (converted into heat in the shock absorbers of a partially loaded vehicle (75% while moving at a speed of 5, m / s. It can be determined that the reduced load on a vehicle leads to reduced thermal shock loading of vehicles, which is in accordance with heat flux.ConclusionBased on

ABSORBENCY CHARACTERISTICS OF PESHTAMALS: TRADITIONAL TURKISH WOVEN CLOTHES

Directory of Open Access Journals (Sweden)

KESKIN Reyhan

2014-05-01

Full Text Available Absorbency of textiles is defined as the ability of taking in a fluid in the manner of a sponge. Absorbency is required for comfort properties in so me clothes such as sportswear and underwear clothing, for drying properties in napkins, towels and bathrobes, for health concerns in some medical textiles such as bandages, gauze and absorbent cotton, and for cleaning properties in washclothes and mops. In this study five different fabric samples (three woven 100% cotton fabrics A, B and P respectively at plain, twill, and peshtamal weaving patterns and two 100% cotton terry towels T1 and T2 were tested. The absorbency properties of the samples were evaluated according to the droplet test, sinking time test and wicking height tests (pottasium chromate test. Peshtamal samples showed better absorbency results than plain and twill weaves and lower but close results to towel samples according to the droplet test, sinking time test and wicking height tests. The absorbency properties of peshtamals showed results close to towel samples. The void content of peshtamals is higher than plain and twill samples but closer and lower than towel samples. The good absorbency results of peshtamals might be due to the void content of peshtamals which is higher than plain and twill samples but closer and lower than towel samples. Peshtamals which are good in absorbency and light in weight might be used widespreadly in daily life for their high absorbency, and on travel for weight saving purposes.

Comments on liquid hydrogen absorbers for MICE

International Nuclear Information System (INIS)

Green, Michael A.

2003-01-01

This report describes the heat transfer problems associated with a liquid hydrogen absorber for the MICE experiment. This report describes a technique for modeling heat transfer from the outside world, to the absorber case and in its vacuum vessel, to the hydrogen and then into helium gas at 14 K. Also presented are the equation for free convection cooling of the liquid hydrogen in the absorber

DYNAMICALLY DRIVEN EVOLUTION OF THE INTERSTELLAR MEDIUM IN M51

International Nuclear Information System (INIS)

Koda, Jin; Scoville, Nick; Potts, Ashley E.; Carpenter, John M.; Corder, Stuartt A.; Patience, Jenny; Sargent, Anneila I.; Sawada, Tsuyoshi; La Vigne, Misty A.; Vogel, Stuart N.; White, Stephen M.; Zauderer, B. Ashley; Pound, Marc W.; Wright, Melvyn C. H.; Plambeck, Richard L.; Bock, Douglas C. J.; Hawkins, David; Hodges, Mark; Lamb, James W.; Kemball, Athol

2009-01-01

Massive star formation occurs in giant molecular clouds (GMCs); an understanding of the evolution of GMCs is a prerequisite to develop theories of star formation and galaxy evolution. We report the highest-fidelity observations of the grand-design spiral galaxy M51 in carbon monoxide (CO) emission, revealing the evolution of GMCs vis-a-vis the large-scale galactic structure and dynamics. The most massive GMCs (giant molecular associations (GMAs)) are first assembled and then broken up as the gas flow through the spiral arms. The GMAs and their H 2 molecules are not fully dissociated into atomic gas as predicted in stellar feedback scenarios, but are fragmented into smaller GMCs upon leaving the spiral arms. The remnants of GMAs are detected as the chains of GMCs that emerge from the spiral arms into interarm regions. The kinematic shear within the spiral arms is sufficient to unbind the GMAs against self-gravity. We conclude that the evolution of GMCs is driven by large-scale galactic dynamics-their coagulation into GMAs is due to spiral arm streaming motions upon entering the arms, followed by fragmentation due to shear as they leave the arms on the downstream side. In M51, the majority of the gas remains molecular from arm entry through the interarm region and into the next spiral arm passage.

Study of the behaviour of inorganic ion exchangers in the treatment of medium active effluents. Part IV

International Nuclear Information System (INIS)

Beaven, G.W.; Cross, J.E.; Hooper, E.W.

1988-01-01

This report summarises some of the results from an ongoing experimental programme of work for the Department of the Environment on the potential use of inorganic ion exchangers for the treatment of medium active waste streams. Six different absorbers have been examined for their effectiveness in removing Am, Cs, Co, Sb, Ru, Eu, Ag, Zr, Nb, Zn and Mn ions from solutions varying from 4 M HNO 3 to 1 M NaNO 3 at pH 10. The ion exchangers tested were polyantimonic acid, hydrous titanium oxide, manganese dioxide, potassium copper hexacyanoferrate II, titanium phosphate and zirconium phosphate. The experimental results show that by suitable choice of absorber and operating conditions, good decontamination from all the radionuclides examined can be achieved. (author)

The turbulent life of dust grains in the supernova-driven, multiphase interstellar medium

Science.gov (United States)

Peters, Thomas; Zhukovska, Svitlana; Naab, Thorsten; Girichidis, Philipp; Walch, Stefanie; Glover, Simon C. O.; Klessen, Ralf S.; Clark, Paul C.; Seifried, Daniel

2017-06-01

Dust grains are an important component of the interstellar medium (ISM) of galaxies. We present the first direct measurement of the residence times of interstellar dust in the different ISM phases, and of the transition rates between these phases, in realistic hydrodynamical simulations of the multiphase ISM. Our simulations include a time-dependent chemical network that follows the abundances of H+, H, H2, C+ and CO and take into account self-shielding by gas and dust using a tree-based radiation transfer method. Supernova explosions are injected either at random locations, at density peaks, or as a mixture of the two. For each simulation, we investigate how matter circulates between the ISM phases and find more sizeable transitions than considered in simple mass exchange schemes in the literature. The derived residence times in the ISM phases are characterized by broad distributions, in particular for the molecular, warm and hot medium. The most realistic simulations with random and mixed driving have median residence times in the molecular, cold, warm and hot phase around 17, 7, 44 and 1 Myr, respectively. The transition rates measured in the random driving run are in good agreement with observations of Ti gas-phase depletion in the warm and cold phases in a simple depletion model. ISM phase definitions based on chemical abundance rather than temperature cuts are physically more meaningful, but lead to significantly different transition rates and residence times because there is no direct correspondence between the two definitions.

Electrically driven hybrid photonic metamaterials for multifunctional control

Science.gov (United States)

Kang, Lei; Liu, Liu; Campbell, Sawyer D.; Yue, Taiwei; Ren, Qiang; Mayer, Theresa S.; Werner, Douglas H.

2017-08-01

The unique light-matter interaction in metamaterials, a type of artificial medium in which the geometrical features of subunits dominate their optical responses, have been utilized to achieve exotic material properties that are rare or nonexistent in natural materials. Furthermore, to extend their behaviors, active materials have been introduced into metamaterial systems to advance tunability, switchability and nonlinearity. Nevertheless, practical examples of versatile photonic metamaterials remain exceedingly rare for two main reasons. On the one hand, in sharp contrast to the broad material options available at lower frequencies, it is less common to find active media in the optical regime that can provide pronounced dielectric property changes under external stimuli, such as electric and magnetic fields. Vanadium dioxide (VO2), offering a large refractive index variation over a broad frequency range due to its near room temperature insulator-to-metal transition (IMT), has been favored in recent studies on tunable metamaterials. On the other hand, it turns out that regulating responses of hybrid metamaterials to external forces in an integrated manner is not a straightforward task. Recently, metamaterial-enabled devices (i.e., metadevices) with `self-sufficient' or `self-contained' electrical and optical properties have enabled complex functionalities. Here, we present a design methodology along with the associated experimental validation of a VO2 thin film integrated optical metamaterial absorber as a hybrid photonic platform for electrically driven multifunctional control, including reflectance switching, a rewritable memory process and manageable localized camouflage. The nanoengineered topologically continuous metal structure simultaneously supports the optical resonance and electrical functionality that actuates the phase transition in VO2 through the process of Joule heating. This work provides a universal approach to creating self-sufficient and highly

Evidence for Pulsation-Driven Mass Loss from δ Cephei

Science.gov (United States)

Marengo, M.; Evans, N. R.; Matthews, L. D.; Bono, G.; Barmby, P.; Welch, D. L.; Romaniello, M.; Su, K. Y. L.; Fazio, G. G.; Huelsman, D.

We found the first direct evidence that the Cepheid class namesake, δ Cephei, is currently losing mass. These observations are based on data obtained with the Spitzer Space Telescope in the infrared, and with the Very Large Array in the radio. We found that δ Cephei is associated with a vast circumstellar structure, reminiscent of a bow shock. This structure is created as the wind from the star interacts with the local interstellar medium. We measure an outflow velocity of ≈ 35. 5 km s- 1 and a mass loss rate of ≈ 10- 7-10- 6 M ⊙ year- 1. The very low dust content of the outflow suggests that the wind is possibly pulsation-driven, rather than dust-driven as common for other classes of evolved stars.

In-silico-driven metabolic engineering of Pseudomonas putida for enhanced production of poly-hydroxyalkanoates

NARCIS (Netherlands)

Poblete-Castro, I.; Binger, D.; Rodrigues, A.; Becker, J.; Martins Dos Santos, V.A.P.; Wittmann, C.

2013-01-01

Here, we present systems metabolic engineering driven by in-silico modeling to tailor Pseudomonas putida for synthesis of medium chain length PHAs on glucose. Using physiological properties of the parent wild type as constraints, elementary flux mode analysis of a large-scale model of the metabolism

Method of absorbance correction in a spectroscopic heating value sensor

Science.gov (United States)

Saveliev, Alexei; Jangale, Vilas Vyankatrao; Zelepouga, Sergeui; Pratapas, John

2013-09-17

A method and apparatus for absorbance correction in a spectroscopic heating value sensor in which a reference light intensity measurement is made on a non-absorbing reference fluid, a light intensity measurement is made on a sample fluid, and a measured light absorbance of the sample fluid is determined. A corrective light intensity measurement at a non-absorbing wavelength of the sample fluid is made on the sample fluid from which an absorbance correction factor is determined. The absorbance correction factor is then applied to the measured light absorbance of the sample fluid to arrive at a true or accurate absorbance for the sample fluid.

Adaptive inertial shock-absorber

International Nuclear Information System (INIS)

Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

2016-01-01

This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated. (paper)

Microscopic analysis of saturable absorbers: Semiconductor saturable absorber mirrors versus graphene

Energy Technology Data Exchange (ETDEWEB)

Hader, J.; Moloney, J. V. [Nonlinear Control Strategies, Inc., 3542 N. Geronimo Ave., Tucson, Arizona 85705 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Yang, H.-J.; Scheller, M. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Koch, S. W. [Department of Physics and Materials Sciences Center, Philipps Universität Marburg, Renthof 5, 35032 Marburg (Germany)

2016-02-07

Fully microscopic many-body calculations are used to study the influence of strong sub-picosecond pulses on the carrier distributions and corresponding optical response in saturable absorbers used for mode-locking—semiconductor (quantum well) saturable absorber mirrors (SESAMs) and single layer graphene based saturable absorber mirrors (GSAMs). Unlike in GSAMs, the saturation fluence and recovery time in SESAMs show a strong spectral dependence. While the saturation fluence in the SESAM is minimal at the excitonic bandgap, the optimal recovery time and least pulse distortion due to group delay dispersion are found for excitation higher in the first subband. For excitation near the SESAM bandgap, the saturation fluence is about one tenth of that in the GSAM. At energies above the bandgap, the fluences in both systems become similar. A strong dependence of the saturation fluence on the pulse width in both systems is caused by carrier relaxation during the pulse. The recovery time in graphene is found to be about two to four times faster than that in the SESAMs. The occurrence of negative differential transmission in graphene is shown to be caused by dopant related carriers. In SESAMs, a negative differential transmission is found when exciting below the excitonic resonance where excitation induced dephasing leads to an enhancement of the absorption. Comparisons of the simulation data to the experiment show a very good quantitative agreement.

Memory bias for negative emotional words in recognition memory is driven by effects of category membership.

Science.gov (United States)

White, Corey N; Kapucu, Aycan; Bruno, Davide; Rotello, Caren M; Ratcliff, Roger

2014-01-01

Recognition memory studies often find that emotional items are more likely than neutral items to be labelled as studied. Previous work suggests this bias is driven by increased memory strength/familiarity for emotional items. We explored strength and bias interpretations of this effect with the conjecture that emotional stimuli might seem more familiar because they share features with studied items from the same category. Categorical effects were manipulated in a recognition task by presenting lists with a small, medium or large proportion of emotional words. The liberal memory bias for emotional words was only observed when a medium or large proportion of categorised words were presented in the lists. Similar, though weaker, effects were observed with categorised words that were not emotional (animal names). These results suggest that liberal memory bias for emotional items may be largely driven by effects of category membership.

A hot air driven thermoacoustic-Stirling engine

Energy Technology Data Exchange (ETDEWEB)

Tijani, M.E.H.; Spoelstra, S. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

2012-09-15

Significant energy savings can be obtained by implementing a thermally driven heat pump into industrial or domestic applications. Such a thermally driven heat pump uses heat from a high-temperature source to drive the system which upgrades an abundantly available heat source (industrial waste heat, air, water, geothermal). A way to do this is by coupling a thermoacoustic engine with a thermoacoustic heat pump. The engine is driven by a burner and produces acoustic power and heat at the required temperature. The acoustic power is used to pump heat in the heat pump to the required temperature. This system is attractive since it uses a noble gas as working medium and has no moving mechanical parts. This paper deals with the first part of this system: the engine. In this study, hot air is used to simulate the flue gases originating from a gas burner. This is in contrast with a lot of other studies of thermoacoustic engines that use an electrical heater as heat source. Using hot air resembles to a larger extent the real world application. The engine produces about 300W of acoustic power with a performance of 41% of the Carnot efficiency at a hot air temperature of 620C.

Adaptive Piezoelectric Absorber for Active Vibration Control

Directory of Open Access Journals (Sweden)

Sven Herold

2016-02-01

Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

Absorbent material for type a radioactive materials packaging containing liquids

International Nuclear Information System (INIS)

Saunders, G.A.

1989-11-01

The application of absorbent materials to the packaging and transport of liquid radioactive materials in Type A packages has not been reported in the literature. However, a significant body of research exists on absorbent materials for personal hygiene products such as diapers. Absorption capacity is dependent on both the absorbent material and the liquid being absorbed. Theoretical principles for capillary absorption in both the horizontal and the vertical plane indicate that small contact angle between the absorbent fibre and the liquid, and a small inter-fibre pore size are important. Some fluid parameters such as viscosity affect the rate of absorption but not the final absorption capacity. There appears to be little comparability between results obtained for the same absorbent and fluid using different test procedures. Test samples of materials from several classes of potential absorbents have been evaluated in this study, and shown to have a wide range of absorbent capacities. Foams, natural fibres, artificial fibres and granular materials are all potentially useful absorbents, with capacities ranging from as little as 0.86 to as much as 40.6 grams of distilled water per gram of absorbent. Two experimental procedures for evaluating the absorbent capacity of these materials have been detailed in this report, and found suitable for evaluating granular, fibrous or foam materials. Compression of the absorbent material reduces its capacity, but parameters such as relative humidity, pH, temperature, and viscosity appear to have little significant influence on capacity. When the materials were loaded to 50% of their one-minute absorbency, subsequent loss of the absorbed liquid was generally minimal. All of the absorbent materials rapidly lost their absorbed water through evaporation within twenty-four hours in still air at 21 degrees C and 50% relative humidity

A computational model of amoeboid cell swimming in unbounded medium and through obstacles

Science.gov (United States)

Campbell, Eric; Bagchi, Prosenjit

2017-11-01

Pseudopod-driven motility is commonly observed in eukaryotic cells. Pseudopodia are actin-rich protrusions of the cellular membrane which extend, bifurcate, and retract in cycles resulting in amoeboid locomotion. While actin-myosin interactions are responsible for pseudopod generation, cell deformability is crucial concerning pseudopod dynamics. Because pseudopodia are highly dynamic, cells are capable of deforming into complex shapes over time. Pseudopod-driven motility represents a multiscale and complex process, coupling cell deformation, protein biochemistry, and cytoplasmic and extracellular fluid motion. In this work, we present a 3D computational model of amoeboid cell swimming in an extracellular medium (ECM). The ECM is represented as a fluid medium with or without obstacles. The model integrates full cell deformation, a coarse-grain reaction-diffusion system for protein dynamics, and fluid interaction. Our model generates pseudopodia which bifurcate and retract, showing remarkable similarity to experimental observations. Influence of cell deformation, protein diffusivity and cytoplasmic viscosity on the swimming speed is analyzed in terms of altered pseudopod dynamics. Insights into the role of matrix porosity and obstacle size on cell motility are also provided. Funded by NSF CBET 1438255.

Selective solar absorber emittance measurement at elevated temperature

Science.gov (United States)

Giraud, Philémon; Braillon, Julien; Raccurt, Olivier

2017-06-01

Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The characterization of a material in such condition is complicated and requires advanced apparatuses, and different measurement methods exist for the determination of the two quantities of relevance regarding an absorber, which are its emittance and its solar absorbance. The objective is to develop new optical equipment for measure the emittance of this solar absorber at elevated temperature. In this paper, we present an optical bench developed for emittance measurement on absorbers is conditions of use. Results will be shown, with a discussion of some factors of influence over this measurement and how to control them.

A shock absorber model for structure-borne noise analyses

Science.gov (United States)

Benaziz, Marouane; Nacivet, Samuel; Thouverez, Fabrice

2015-08-01

Shock absorbers are often responsible for undesirable structure-borne noise in cars. The early numerical prediction of this noise in the automobile development process can save time and money and yet remains a challenge for industry. In this paper, a new approach to predicting shock absorber structure-borne noise is proposed; it consists in modelling the shock absorber and including the main nonlinear phenomena responsible for discontinuities in the response. The model set forth herein features: compressible fluid behaviour, nonlinear flow rate-pressure relations, valve mechanical equations and rubber mounts. The piston, base valve and complete shock absorber model are compared with experimental results. Sensitivity of the shock absorber response is evaluated and the most important parameters are classified. The response envelope is also computed. This shock absorber model is able to accurately reproduce local nonlinear phenomena and improves our state of knowledge on potential noise sources within the shock absorber.

Experimental and Numerical Studies of Particle Acceleration by an Active Microwave Medium

CERN Document Server

Schoessow, Paul

2005-01-01

There has been considerable theoretical work on the so-called PASER concept, in which a particle beam is accelerated directly by absorbing energy from an active medium, analogous to the amplification of an optical signal in a laser. Use of an active microwave (maser) medium would have the advantage of requiring relaxed beam quality (mm vs. nm characteristic beam dimensions). Recent work using electron paramagnetic resonance (EPR) techniques has demonstrated activity in the microwave regime (i.e. negative imaginary part of the magnetic susceptibility) for a class of organic compounds. A solution of fullerene (C60) in a liquid crystal solvent has been reported in the literature to possess a maser transition in the X-band region. An external DC magnetic field is required to obtain the effect; the frequency of the maser transition is adjustable by varying the magnetic field strength. We will report on the development of numerical and laboratory tools to evaluate the use of this material for accelerator applicatio...

The development of national quality performance standards for disposable absorbent products for adult incontinence.

Science.gov (United States)

Muller, Nancy; McInnis, Elaine

2013-09-01

evaluate absorbent products (medium adult size): Maximum Rewet Rate: 250 g for standard briefs or underwear and >400 g for premium briefs or underwear; and Breathability of Zones: Minimum of >100 cubic feet per minute. As these recommendations are implemented, research is needed to evaluate the impact on both cost and quality of care for further refinement and modifications, particularly as technology and knowledge is advanced.

The Cooling of a Liquid Absorber using a Small Cooler

International Nuclear Information System (INIS)

Baynham, D.E.; Bradshaw, T.W.; Green, M.A.; Ishimoto, S.; Liggins, N.

2005-01-01

This report discusses the use of small cryogenic coolers for cooling the Muon Ionization Cooling Experiment (MICE) liquid cryogen absorbers. Since the absorber must be able contain liquid helium as well liquid hydrogen, the characteristics of the available 4.2 K coolers are used here. The issues associated with connecting two-stage coolers to liquid absorbers are discussed. The projected heat flows into an absorber and the cool-down of the absorbers using the cooler are presented. The warm-up of the absorber is discussed. Special hydrogen safety issues that may result from the use of a cooler on the absorbers are also discussed

Gas cooled high temperature reactor with a heap of pebble shaped fuel elements and absorber rods which can be driven directly into the heap of pebbles

International Nuclear Information System (INIS)

Elter, C.; Schmitt, H.; Schoening, J.; Weicht, U.

1980-01-01

The absorber rod for the graphite moderated, helium cooled reactor is cylindrical and has a tip in the shape of the frustrum of a cone. It consists of three coaxially arranged sleeve tubes made of steel, the inner and centre sleeve tubes surrounding the absorber part (B4C) so as to be gastight. The inner sleeve tube represents the supporting tube and is cooled by cold gas, as is the annular gap between the centre and outer sleeve tube. (RW) [de

Design and development of radiation absorber for sighting beam line

International Nuclear Information System (INIS)

Sridhar, R.; Shukla, S.K.

2005-01-01

During the commissioning of Indus-2 , it is necessary to view the synchrotron radiation that will be emanating from the dipole exit ports. The 10 0 beam line from dipole 11 was earmarked for sighting beam line. The synchrotron radiation power density would be around 340 watts on the photon absorber inside the radiation absorber module, at the specified beam power of Indus-2. The beam striking on this photon absorber produces x-rays and Bremsstrahlung radiation. These are to be stopped and absorbed by radiation absorber. The photon absorber and the radiation absorber are integrated in a single vacuum chamber and actuated by a pneumatic cylinder connected using a bellow. Radiation absorber was needed to isolate the diagnostic components and to protect them from radiation a well as heat when they were not in use. The paper describes the design, calculation and development of the dynamic photon cum radiation absorber. The ultimate vacuum performance is also described. (author)

Thin absorbers for large-area soft X-ray microcalorimeters

Energy Technology Data Exchange (ETDEWEB)

Rocks, L. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)]. E-mail: rocks@wisp.physics.wisc.edu; Anderson, M.B. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Bilgri, N. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Brekosky, R. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gwynne Crowder, S. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Figueroa-Feliciano, E. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kelley, R. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kilbourne, C.A. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lai, T. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Lindeman, M.A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Man, J. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); McCammon, D. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Nelms, K.L. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Porter, F.S. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sivananthan, S. [University of Illinois at Chicago, Chicago, IL 60607 (United States); Vidugiris, G. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Zhao, J. [University of Illinois at Chicago, Chicago, IL 60607 (United States)

2006-04-15

The X-ray Quantum Calorimeter (XQC) sounding rocket experiment utilizes a microcalorimeter array for observing the diffuse soft X-ray background. Observations of such low surface-brightness targets require a large-area detector. We will be using an array of large absorbers. Good absorbers must rapidly and completely thermalize photons, have small heat capacity for high stopping efficiency and have good lateral thermal transport. For observing the soft X-ray background (energies <1 keV), the volume and heat capacity of absorber material can be kept to a minimum by making the absorbers only as thick as needed for high quantum efficiency at these low energies. These thin, large-area absorbers are not self-supporting and have poor lateral heat transport. Depositing the absorber material on a Si substrate provides support and improves lateral thermal conduction. We present heat capacity results for thin HgTe and thin Bi, each on Si substrates. We also describe the HgTe absorber fabrication.

Absorbed dose by a CMOS in radiotherapy

International Nuclear Information System (INIS)

Borja H, C. G.; Valero L, C. Y.; Guzman G, K. A.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R.; Paredes G, L. C.

2011-10-01

Absorbed dose by a complementary metal oxide semiconductor (CMOS) circuit as part of a pacemaker, has been estimated using Monte Carlo calculations. For a cancer patient who is a pacemaker carrier, scattered radiation could damage pacemaker CMOS circuits affecting patient's health. Absorbed dose in CMOS circuit due to scattered photons is too small and therefore is not the cause of failures in pacemakers, but neutron calculations shown an absorbed dose that could cause damage in CMOS due to neutron-hydrogen interactions. (Author)

GLOBAL GALACTIC DYNAMO DRIVEN BY COSMIC RAYS AND EXPLODING MAGNETIZED STARS

International Nuclear Information System (INIS)

Hanasz, Michal; Woltanski, Dominik; Kowalik, Kacper

2009-01-01

We report the first results of the first global galactic-scale cosmic ray (CR)-MHD simulations of CR-driven dynamo. We investigate the dynamics of magnetized interstellar medium (ISM), which is dynamically coupled with CR gas. We assume that exploding stars deposit small-scale, randomly oriented, dipolar magnetic fields into the differentially rotating ISM, together with a portion of CRs, accelerated in supernova shocks. We conduct numerical simulations with the aid of a new parallel MHD code PIERNIK. We find that the initial magnetization of galactic disks by exploding magnetized stars forms favorable conditions for the CR-driven dynamo. We demonstrate that dipolar magnetic fields supplied on small supernova remnant scales can be amplified exponentially by the CR-driven dynamo, to the present equipartition values, and transformed simultaneously to large galactic scales. The resulting magnetic field structure in an evolved galaxy appears spiral in the face-on view and reveals the so-called X-shaped structure in the edge-on view.

An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides

International Nuclear Information System (INIS)

Wang Ziming; Zhao Xin; Xu Xu; Wu Lijie; Su Rui; Zhao Yajing; Jiang Chengfei; Zhang Hanqi; Ma Qiang; Lu Chunmei; Dong Deming

2013-01-01

Highlights: ► An absorbing microwave μ-SPE device packed with activated carbon was used. ► Absorbing microwave μ-SPE device was made and used to enrich the analytes. ► Absorbing microwave μ-SPE device was made and used to heat samples directly. ► MAE-μ-SPE was applied to the extraction of OPPs with non-polar solvent only. - Abstract: A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction (μ-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave μ-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in μ-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave μ-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60 °C for 10 min. The extracts obtained by MAE-μ-SPE were directly analyzed by GC–MS without any clean-up process. The recoveries were in the range of 93.5–104.6%, and the relative standard deviations were lower than 8.7%.

Participation of cob tissue in the transport of medium components into maize kernels cultured in vitro

International Nuclear Information System (INIS)

Felker, F.C.

1990-01-01

Maize (Zea mays L.) kernels cultured in vitro while still attached to cob pieces have been used as a model system to study the physiology of kernel development. In this study, the role of the cob tissue in uptake of medium components into kernels was examined. Cob tissue was essential for in vitro kernel growth, and better growth occurred with larger cob/kernel ratios. A symplastically transported fluorescent dye readily permeated the endosperm when supplied in the medium, while an apoplastic dye did not. Slicing the cob tissue to disrupt vascular connections, but not apoplastic continuity, greatly reduced [ 14 C]sucrose uptake into kernels. [ 14 C]Sucrose uptake by cob and kernel tissue was reduced 31% and 68%, respectively, by 5 mM PCMBS. L-[ 14 C]glucose was absorbed much more slowly than D-[ 14 C]glucose. These and other results indicate that phloem loading of sugars occurs in the cob tissue. Passage of medium components through the symplast cob tissue may be a prerequisite for uptake into the kernel. Simple diffusion from the medium to the kernels is unlikely. Therefore, the ability of substances to be transported into cob tissue cells should be considered in formulating culture medium

Absorbed dose calculation of the energy deposition close to bone, lung and soft tissue interfaces in molecular radiotherapy

International Nuclear Information System (INIS)

Fernandez, M.; Lassman, M.

2015-01-01

Full text of publication follows. Aim: for voxel-based dosimetry in molecular radiotherapy (MRT) based on tabulated voxel S-values these values are usually obtained only for soft tissue. In order to study the changes in the dose deposition patterns at interfaces between different materials we have performed Monte Carlo simulations. Methods: the deposited energy patterns were obtained using the Monte-Carlo radiation code MCNPX v2.7 for Lu 177 (medium-energy) and Y 90 (high-energy). The following interfaces were studied: soft tissue-bone and soft tissue-lungs. For this purpose a volume of soft tissue homogeneously filled with Lu 177 or Y 90 was simulated at the interface to 3 different volumes containing no activity: soft tissue, lungs and bone. The emission was considered to be isotropic. The dimensions were chosen to ensure that the energy deposited by all generated particles was scored. The materials were defined as recommended by ICPR46; the decay schemes of Eckerman and Endo were used. With these data the absorbed dose patterns normalized to the maximum absorbed dose in the source region (soft tissue) were calculated. Results: the absorbed dose fractions in the boundary with soft tissue, bone and lungs are 50%, 47% and 57%, respectively, for Lu 177 and 50%, 47% and 51% for Y 90 . The distances to the interface at which the absorbed fractions are at 0.1% are 1.0, 0.6 and 3.0 mm for Lu 177 and 7.0, 4.0 and 24 mm for Y 90 , for soft tissue, bone and lungs respectively. Conclusions: in MRT, the changes in the absorbed doses at interfaces between soft tissue and bone/lungs need to be considered for isotopes emitting high energy particles. (authors)

Air box shock absorber for a nuclear reactor

International Nuclear Information System (INIS)

Pradhan, A.V.; George, J.A.

1977-01-01

Disclosed is an air box type shock absorber primarily for use in an ice condenser compartment of a nuclear reactor. The shock absorber includes a back plate member and sheet metal top, bottom, and front members. The front member is prefolded, and controlled clearances are provided among the members for predetermined escape of air under impact and compression. Prefolded internal sheet metal stiffeners also absorb a portion of the kinetic energy imparted to the shock absorber, and limit rebound. An external restraining rod guided by restraining straps insures that the sheet metal front member compresses inward upon impact. 6 claims, 11 figures

Absorber element for fast breeder reactor

International Nuclear Information System (INIS)

Verset, L.

1987-01-01

This absorber element is characterized by a new head which avoids an accident disconnection of the mobil absorber. This head is made by a superior piece which can take shore up an adjusting ring on an adjusting bearing on the inferior piece. The intermediate piece is catched at the superior piece by a link of chain [fr

Absorbed dose by a CMOS in radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Borja H, C. G.; Valero L, C. Y.; Guzman G, K. A.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L. C., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2011-10-15

Absorbed dose by a complementary metal oxide semiconductor (CMOS) circuit as part of a pacemaker, has been estimated using Monte Carlo calculations. For a cancer patient who is a pacemaker carrier, scattered radiation could damage pacemaker CMOS circuits affecting patient's health. Absorbed dose in CMOS circuit due to scattered photons is too small and therefore is not the cause of failures in pacemakers, but neutron calculations shown an absorbed dose that could cause damage in CMOS due to neutron-hydrogen interactions. (Author)

Semiconductor saturable absorbers for ultrafast terahertz signals

DEFF Research Database (Denmark)

Hoffmann, Matthias C.; Turchinovich, Dmitry

2010-01-01

states, due to conduction band onparabolicity and scattering into satellite valleys in strong THz fields. Saturable absorber parameters, such as linear and nonsaturable transmission, and saturation fluence, are extracted by fits to a classic saturable absorber model. Further, we observe THz pulse......We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

Graphene and Graphene Metamaterials for Terahertz Absorbers

DEFF Research Database (Denmark)

Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

2013-01-01

Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows...... for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present our recent experimental results on the graphene absorbers characterization....

Performance of a new carbon dioxide absorbent, Yabashi lime® as compared to conventional carbon dioxide absorbent during sevoflurane anesthesia in dogs.

Science.gov (United States)

Kondoh, Kei; Atiba, Ayman; Nagase, Kiyoshi; Ogawa, Shizuko; Miwa, Takashi; Katsumata, Teruya; Ueno, Hiroshi; Uzuka, Yuji

2015-08-01

In the present study, we compare a new carbon dioxide (CO2) absorbent, Yabashi lime(®) with a conventional CO2 absorbent, Sodasorb(®) as a control CO2 absorbent for Compound A (CA) and Carbon monoxide (CO) productions. Four dogs were anesthetized with sevoflurane. Each dog was anesthetized with four preparations, Yabashi lime(®) with high or low-flow rate of oxygen and control CO2 absorbent with high or low-flow rate. CA and CO concentrations in the anesthetic circuit, canister temperature and carbooxyhemoglobin (COHb) concentration in the blood were measured. Yabashi lime(®) did not produce CA. Control CO2 absorbent generated CA, and its concentration was significantly higher in low-flow rate than a high-flow rate. CO was generated only in low-flow rate groups, but there was no significance between Yabashi lime(®) groups and control CO2 absorbent groups. However, the CO concentration in the circuit could not be detected (≤5ppm), and no change was found in COHb level. Canister temperature was significantly higher in low-flow rate groups than high-flow rate groups. Furthermore, in low-flow rate groups, the lower layer of canister temperature in control CO2 absorbent group was significantly higher than Yabashi lime(®) group. CA and CO productions are thought to be related to the composition of CO2 absorbent, flow rate and canister temperature. Though CO concentration is equal, it might be safer to use Yabashi lime(®) with sevoflurane anesthesia in dogs than conventional CO2 absorbent at the point of CA production.

Ag-water nanofluid flow over an inclined porous plate embedded in a non-Darcy porous medium due to solar radiation

International Nuclear Information System (INIS)

Chakraborty, Tanmoy; Das, Kalidas; Kundu, Prabir Kumar

2017-01-01

The heat absorber uses in solar power plants have generally low energy adaptation owing to large emissive losses at high temperature. Recently, nanofluid based solar energy absorber have acknowledged immense scientific curiosity to competent share and store the thermal energy. Here we examine theoretically the natural convective flow of an Ag nanoparticle based nanofluid flow along an inclined flat sheet embedded in a Darcy-Forchheimer permeable medium coexistence of solar radiation. By use of similarity transformations, the fundamental partial differential system and boundary conditions are tackled numerically using Runge-Kutta Gill based shooting procedure. The impacts of governing parameters upon the flow, temperature, Nusselt number and skin friction coefficient are represented tabular as well as in graphical form.

Ag-water nanofluid flow over an inclined porous plate embedded in a non-Darcy porous medium due to solar radiation

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Tanmoy [Techno India College of Technology, Kolkata (India); Das, Kalidas [A.B.N.Seal College, Cooch Behar (India); Kundu, Prabir Kumar [Jadavpur University, Kolkata (India)

2017-05-15

The heat absorber uses in solar power plants have generally low energy adaptation owing to large emissive losses at high temperature. Recently, nanofluid based solar energy absorber have acknowledged immense scientific curiosity to competent share and store the thermal energy. Here we examine theoretically the natural convective flow of an Ag nanoparticle based nanofluid flow along an inclined flat sheet embedded in a Darcy-Forchheimer permeable medium coexistence of solar radiation. By use of similarity transformations, the fundamental partial differential system and boundary conditions are tackled numerically using Runge-Kutta Gill based shooting procedure. The impacts of governing parameters upon the flow, temperature, Nusselt number and skin friction coefficient are represented tabular as well as in graphical form.

Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels

Science.gov (United States)

Singh, Meenesh R.; Clark, Ezra L.; Bell, Alexis T.

2015-11-01

Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.

Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels.

Science.gov (United States)

Singh, Meenesh R; Clark, Ezra L; Bell, Alexis T

2015-11-10

Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.

Radar absorbing properties of carbon nanotubes/polymer ...

Indian Academy of Sciences (India)

This research is devoted to the study of radar absorbing properties of the composites, based on the epoxy binder and ... Radar absorbing materials; carbon nanotubes; nanocomposites; reflection loss. 1. ..... So, for example, the papers of [3–5 ...

GEOMETRICAL OPTIMIZATION OF VEHICLE SHOCK ABSORBERS WITH MR FLUID

OpenAIRE

ENGIN, Tahsin; PARLAK, Zekeriya; ŞAHIN, Ismail; ÇALLI, Ismail

2016-01-01

Magnetorheological (MR) shock absorber have received remarkable attention in the last decade due to being a potential technology to conduct semi-active control in structures and mechanical systems in order to effectively suppress vibration. To develop performance of MR shock absorbers, optimal design of the dampers should be considered. The present study deals with optimal geometrical modeling of a MR shock absorber. Optimal design of the present shock absorber was carried out by using Taguch...

Measurement of the Decay of Thermal Neutrons in Water Poisoned with the Non-1/v Neutron Absorber Cadmium

Energy Technology Data Exchange (ETDEWEB)

Larsson, L G; Moeller, E

1968-01-15

Measurements have been made of the decay constant of thermal neutrons in water poisoned with the non-1/v absorber cadmium. An experimental method has been used in which proper spatial integration of the neutron flux enables data, representative of the infinite medium to be accumulated without waiting for the establishment of a fundamental mode distribution. The change in effective cross section with concentration of the dissolved cadmium, d{sigma}{sub eff}/dN. has been determined for infinite medium at 20 deg C. Two- and three parameter fits of the decay constant yield -(0.32 {+-} 0.09) x 10{sup -17} barn cm{sup 3} and -(0.47 {+-} 0.10) x 10{sup -17} barn cm{sup 3}, respectively. Earlier published measurements have resulted in two to five times larger values, whereas a published calculated value of Nelkin's model is - 0.33 x 10{sup -17} barn cm{sup 3}.

Measurement of the Decay of Thermal Neutrons in Water Poisoned with the Non-1/v Neutron Absorber Cadmium

International Nuclear Information System (INIS)

Larsson, L.G.; Moeller, E.

1968-01-01

Measurements have been made of the decay constant of thermal neutrons in water poisoned with the non-1/v absorber cadmium. An experimental method has been used in which proper spatial integration of the neutron flux enables data, representative of the infinite medium to be accumulated without waiting for the establishment of a fundamental mode distribution. The change in effective cross section with concentration of the dissolved cadmium, dσ eff /dN. has been determined for infinite medium at 20 deg C. Two- and three parameter fits of the decay constant yield -(0.32 ± 0.09) x 10 -17 barn cm 3 and -(0.47 ± 0.10) x 10 -17 barn cm 3 , respectively. Earlier published measurements have resulted in two to five times larger values, whereas a published calculated value of Nelkin's model is - 0.33 x 10 -17 barn cm 3

Progress on the MICE Liquid Absorber Cooling and Cryogenic Distribution System

International Nuclear Information System (INIS)

Green, M.A.; Baynham, E.; Bradshaw, T.; Drumm, P.; Ivanyushenkov, Y.; Ishimoto, S.; Cummings, M.A.C.; Lau, W.W.; Yang, S.Q.

2005-01-01

This report describes the progress made on the design of the cryogenic cooling system for the liquid absorber for the international Muon Ionization Cooling Experiment (MICE). The absorber consists of a 20.7-liter vessel that contains liquid hydrogen (1.48 kg at 20.3 K) or liquid helium (2.59 kg at 4.2 K). The liquid cryogen vessel is located within the warm bore of the focusing magnet for the MICE. The purpose of the magnet is to provide a low beam beta region within the absorber. For safety reasons, the vacuum vessel for the hydrogen absorber is separated from the vacuum vessel for the superconducting magnet and the vacuum that surrounds the RF cavities or the detector. The absorber thin windows separate the liquid in the absorber from the absorber vacuum. The absorber vacuum vessel also has thin windows that separate the absorber vacuum space from adjacent vacuum spaces. Because the muon beam in MICE is of low intensity, there is no beam heating in the absorber. The absorber can use a single 4 K cooler to cool either liquid helium or liquid hydrogen within the absorber

Preparation and characterization of water-absorbing composite ...

African Journals Online (AJOL)

The present work introduces a novel method for the formation of water absorbing composite membrane. The prepared composite is based on chitosan, carboxymethyl cellulose (CMC), and Montmorillonite. Prepared composite membrane exhibits high water absorbing and holding capacity with increasing clay content.

Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

Energy Technology Data Exchange (ETDEWEB)

Stynes, J. K.; Ihas, B.

2012-04-01

As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

Evaluation of a flue gas driven open absorption system for heat and water recovery from fossil fuel boilers

International Nuclear Information System (INIS)

Wang, Zhenying; Zhang, Xiaoyue; Li, Zhen

2016-01-01

Highlights: • Flue gas driven open absorption system that efficiently recovers total heat. • Efficient heat and water recovery for various kinds of fossil fuel boilers. • Heat and water recovery efficiencies increase with moisture content of flue gas. • Temperature requirements for district heat supply and domestic hot water were met. • Experimental system surpasses conventional condensing system in total heat recovery. - Abstract: This paper presents an open absorption system for total heat recovery from fossil fuel boilers using the high temperature flue gas as the regeneration heat source. In this system, liquid desiccant serves as the recycling medium, which absorbs waste heat and moisture contained in the low temperature flue gas in the packed tower and then regenerates in the regenerator by the high temperature flue gas. Water vapor generated in the regenerator gets condensed after releasing heat to the heating water system and the condensing water also gets recycled. The return water collects heat from the solution water heat exchanger, the flue gas water heat exchanger and the condenser respectively and is then used for district heating. Driven by the vapor pressure difference between high humidity flue gas and the liquid desiccant, the heat recovery efficiency of the system is not limited by the dew point of the flue gas, enabling a warmer water to be heated up than the conventional condensing boiler. The performance of this system was analyzed theoretically and experimentally and the results showed that the system operated well for both district heat supply and domestic hot water supply. The system efficiency increased with the moisture content of flue gas and the total heat recovery was about 8.5%, 17.2%, 21.2%, and 9.2% higher than the conventional condensing system in the case of coal fired boiler, fuel oil boiler, natural gas boiler, and coke oven gas boiler, respectively.

Ni-Al Alloys as Alternative EUV Mask Absorber

Directory of Open Access Journals (Sweden)

Vu Luong

2018-03-01

Full Text Available Extreme ultraviolet (EUV lithography is being industrialized as the next candidate printing technique for high-volume manufacturing of scaled down integrated circuits. At mask level, the combination of EUV light at oblique incidence, absorber thickness, and non-uniform mirror reflectance through incidence angle, creates photomask-induced imaging aberrations, known as mask 3D (M3D effects. A possible mitigation for the M3D effects in the EUV binary intensity mask (BIM, is to use mask absorber materials with high extinction coefficient κ and refractive coefficient n close to unity. We propose nickel aluminide alloys as a candidate BIM absorber material, and characterize them versus a set of specifications that a novel EUV mask absorber must meet. The nickel aluminide samples have reduced crystallinity as compared to metallic nickel, and form a passivating surface oxide layer in neutral solutions. Composition and density profile are investigated to estimate the optical constants, which are then validated with EUV reflectometry. An oxidation-induced Al L2 absorption edge shift is observed, which significantly impacts the value of n at 13.5 nm wavelength and moves it closer to unity. The measured optical constants are incorporated in an accurate mask model for rigorous simulations. The M3D imaging impact of the nickel aluminide alloy mask absorbers, which predict significant M3D reduction in comparison to reference absorber materials. In this paper, we present an extensive experimental methodology flow to evaluate candidate mask absorber materials.

Growth of micro-crystals in solution by in-situ heating via continuous wave infrared laser light and an absorber

Science.gov (United States)

Pathak, Shashank; Dharmadhikari, Jayashree A.; Thamizhavel, A.; Mathur, Deepak; Dharmadhikari, Aditya K.

2016-01-01

We report on growth of micro-crystals such as sodium chloride (NaCl), copper sulphate (CuSO4), potassium di-hydrogen phosphate (KDP) and glycine (NH2CH2COOH) in solution by in-situ heating using continuous wave Nd:YVO4 laser light. Crystals are grown by adding single walled carbon nanotubes (SWNT). The SWNTs absorb 1064 nm light and act as an in-situ heat source that vaporizes the solvent producing microcrystals. The temporal dynamics of micro-crystal growth is investigated by varying experimental parameters such as SWNT bundle size and incident laser power. We also report crystal growth without SWNT in an absorbing medium: copper sulphate in water. Even though the growth dynamics with SWNT and copper sulphate are significantly different, our results indicate that bubble formation is necessary for nucleation. Our simple method may open up new vistas for rapid growth of seed crystals especially for examining the crystallizability of inorganic and organic materials.

Preparation and characterization of water-absorbing composite ...

African Journals Online (AJOL)

ABCO

2012-08-16

Aug 16, 2012 ... The present work introduces a novel method for the formation of water absorbing composite membrane. The prepared composite is based on chitosan, carboxymethyl cellulose (CMC), and. Montmorillonite. Prepared composite membrane exhibits high water absorbing and holding capacity with increasing ...

Quantitative neutron radiography using neutron absorbing honeycomb

International Nuclear Information System (INIS)

Tamaki, Masayoshi; Oda, Masahiro; Takahashi, Kenji; Ohkubo, Kohei; Tasaka, Kanji; Tsuruno, Akira; Matsubayashi, Masahito.

1993-01-01

This investigation concerns quantitative neutron radiography and computed tomography by using a neutron absorbing honeycomb collimator. By setting the neutron absorbing honeycomb collimator between object and imaging system, neutrons scattered in the object were absorbed by the honeycomb material and eliminated before coming to the imaging system, but the neutrons which were transmitted the object without interaction could reach the imaging system. The image by purely transmitted neutrons gives the quantitative information. Two honeycombs were prepared with coating of boron nitride and gadolinium oxide and evaluated for the quantitative application. The relation between the neutron total cross section and the attenuation coefficient confirmed that they were in a fairly good agreement. Application to quantitative computed tomography was also successfully conducted. The new neutron radiography method using the neutron-absorbing honeycomb collimator for the elimination of the scattered neutrons improved remarkably the quantitativeness of the neutron radiography and computed tomography. (author)

Methods for applying microchannels to separate methane using liquid absorbents, especially ionic liquid absorbents from a mixture comprising methane and nitrogen

Science.gov (United States)

Tonkovich, Anna Lee Y [Dublin, OH; Litt, Robert D [Westerville, OH; Dongming, Qiu [Dublin, OH; Silva, Laura J [Plain City, OH; Lamont, Micheal Jay [Plain City, OH; Fanelli, Maddalena [Plain City, OH; Simmons, Wayne W [Plain city, OH; Perry, Steven [Galloway, OH

2011-10-04

Methods of using microchannel separation systems including absorbents to improve thermal efficiency and reduce parasitic power loss. Energy is typically added to desorb methane and then energy or heat is removed to absorb methane using a working solution. The working solution or absorbent may comprise an ionic liquid, or other fluids that demonstrate a difference in affinity between methane and nitrogen in a solution.

Shock absorber system for nuclear reactor ice condenser compartment

International Nuclear Information System (INIS)

Meier, J.F.; Rudd, G.E.; Pradhan, A.V.; George, J.A.; Lippincott, H.W.; Sutherland, J.D.

1979-01-01

A shock absorber system was designed to absorb the energy imparted to doors in a nuclear reactor ice condenser compartment as they swing rapidly to an open position. Each shock absorber which is installed on a wall adjacent to each door is large and must absorb up to about 40,000 foot pounds of energy. The basic shock absorber component comprises foam enclosed in a synthetic fabric bag having a volume about twice the foam volume. A stainless steel knitted mesh bag of the same volume as the fabric bag, contains the fabric bag and its enclosed foam. To protect the foam and bags during construction activities at the reactor site and from the shearing action of the doors, a protective sheet metal cover is installed over the shock absorber ends and the surface to be contacted by the moving door. With the above shock absorber mounted on a wall behind each door, as the door is forcibly opened by steam pressure and air resulting from a pipe break in the reactor compartment, it swings at a high velocity into contact with the shock absorber, crushes the foam and forces it into the fabric bag excess material thus containing the foam fragmented particles, and minimizes build-up of pressure in the bag as a result of the applied compressive force

Pool fire upon a balsa-filled shock absorber

International Nuclear Information System (INIS)

Fry, C.J.

1990-07-01

When performing a safety assessment of a transport flask with balsa-filled shock absorbers it is important to know how the shock absorbers, which may have the outer skin punctured by an impact, will perform in a fire. A 30 minute pool test, which satisfied all the requirements of a thermal test under the IAEA regulations, was carried out upon a small, balsa-filled shock absorber. The outer steel shell was partly cut away exposing the wood to the fire and the air. The balsa wood prevented 90% of the heat from the fire from being transferred through the shock absorber, even though the balsa was only 133 mm thick. The maximum heat flux through to the inside of the shock absorber due to the burning of the balsa wood was relatively low, 2.8 kW/m 2 , and occurred 2 to 3 hours after the end of the pool fire. (author)

Fire Monitoring - The use of medium resolution satellites (AVHRR, MODIS, TET) for long time series processing and the implementation in User Driven Applications and Services

Science.gov (United States)

Fuchs, E.-M.; Stein, E.; Strunz, G.; Strobl, C.; Frey, C.

2015-04-01

This paper introduces fire monitoring works of two different projects, namely TIMELINE (TIMe Series Processing of Medium Resolution Earth Observation Data assessing Long -Term Dynamics In our Natural Environment) and PHAROS (Project on a Multi-Hazard Open Platform for Satellite Based Downstream Services). It describes the evolution from algorithm development from in applied research to the implementation in user driven applications and systems. Concerning TIMELINE, the focus of the work lies on hot spot detection. A detailed description of the choice of a suitable algorithm (round robin approach) will be given. Moreover, strengths and weaknesses of the AVHRR sensor for hot spot detection, a literature review, the study areas and the selected approach will be highlighted. The evaluation showed that the contextual algorithm performed best, and will therefore be used for final implementation. Concerning the PHAROS project, the key aspect is on the use of satellite-based information to provide valuable support to all phases of disaster management. The project focuses on developing a pre-operational sustainable service platform that integrates space-based EO (Earth Observation), terrestrial sensors and communication and navigation assets to enhance the availability of services and products following a multi-hazard approach.

A multicenter randomized controlled trial comparing absorbable barbed sutures versus conventional absorbable sutures for dermal closure in open surgical procedures.

Science.gov (United States)

Rubin, J Peter; Hunstad, Joseph P; Polynice, Alain; Gusenoff, Jeffrey A; Schoeller, Thomas; Dunn, Raymond; Walgenbach, Klaus J; Hansen, Juliana E

2014-02-01

Barbed sutures were developed to reduce operative time and improve security of wound closure. The authors compare absorbable barbed sutures (V-Loc, Covidien, Mansfield, Massachusetts) with conventional (smooth) absorbable sutures for soft tissue approximation. A prospective multicenter randomized study comparing barbed sutures with smooth sutures was undertaken between August 13, 2009, and January 31, 2010, in 241 patients undergoing abdominoplasty, mastopexy, and reduction mammaplasty. Each patient received barbed sutures on 1 side of the body, with deep dermal sutures eliminated or reduced. Smooth sutures with deep dermal and subcuticular closure were used on the other side as a control. The primary endpoint was dermal closure time. Safety was assessed through adverse event reporting through a 12-week follow-up. A total of 229 patients were ultimately treated (115 with slow-absorbing polymer and 114 with rapid-absorbing polymer). Mean dermal closure time was significantly quicker with the barbed suture compared with the smooth suture (12.0 vs 19.2 minutes; P<.001), primarily due to the need for fewer deep dermal sutures. The rapid-absorbing barbed suture showed a complication profile equivalent to the smooth suture, while the slow-absorbing barbed suture had a higher incidence of minor suture extrusion. Barbed sutures enabled faster dermal closure quicker than smooth sutures, with a comparable complication profile. 1.

Identifying the perfect absorption of metamaterial absorbers

Science.gov (United States)

Duan, G.; Schalch, J.; Zhao, X.; Zhang, J.; Averitt, R. D.; Zhang, X.

2018-01-01

We present a detailed analysis of the conditions that result in unity absorption in metamaterial absorbers to guide the design and optimization of this important class of functional electromagnetic composites. Multilayer absorbers consisting of a metamaterial layer, dielectric spacer, and ground plane are specifically considered. Using interference theory, the dielectric spacer thickness and resonant frequency for unity absorption can be numerically determined from the functional dependence of the relative phase shift of the total reflection. Further, using transmission line theory in combination with interference theory we obtain analytical expressions for the unity absorption resonance frequency and corresponding spacer layer thickness in terms of the bare resonant frequency of the metamaterial layer and metallic and dielectric losses within the absorber structure. These simple expressions reveal a redshift of the unity absorption frequency with increasing loss that, in turn, necessitates an increase in the thickness of the dielectric spacer. The results of our analysis are experimentally confirmed by performing reflection-based terahertz time-domain spectroscopy on fabricated absorber structures covering a range of dielectric spacer thicknesses with careful control of the loss accomplished through water absorption in a semiporous polyimide dielectric spacer. Our findings can be widely applied to guide the design and optimization of the metamaterial absorbers and sensors.

A wideband absorber for television studios

Science.gov (United States)

Baird, M. D. M.

The acoustic treatment in BBC television has taken various forms to date, all of which have been relatively expensive, some of which provide inadequate absorption. An investigation has been conducted into the possibilities of producing a new type of wideband absorber which would be more economic, also taking installation time into account, than earlier designs. This Report describes the absorption coefficient measurements made on various combinations of materials, from which a wideband sound absorber has been developed. The absorber works efficiently between 50 Hz and 10 kHz, is simple and easy to construct using readily available materials, and is fire resistant. The design lends itself, if necessary, to on-site fine tuning, and savings in the region of 50 percent can be achieved in terms of cost and space with respect to previous designs.

Absorbed dose in CT. Comparison by CT dose index

International Nuclear Information System (INIS)

Yamamoto, Kenji; Akazawa, Hiroshi; Andou, Takashi

2002-01-01

Few reports have discussed the absorbed dose on CT units with increased scanning capacity even with the current widespread adoption of multi-slice CT units. To compare and investigate the dose indexes among CT units, we measured the absorbed dose on CT units operating in Nagano Prefecture Japan. The measurements showed proportionality between phantom absorbed dose and the exposured mAs values in conventional scanning operation. Further, the measurements showed that the absorbed dose in the center of the phantom differed by about 2.1-fold between the highest and lowest levels on individual CT units. Within a single company, multi-slice CT units of the same company gave absorbed doses of about 1.3 to 1.5 times those of conventional single-slice CT units under the same exposured conditions of conventional scanning. When the scanning pitch was reduced in helical scanning, the absorbed dose at the center of the phantom increased. (author)

Analysis of combined conduction and radiation heat transfer in presence of participating medium by the development of hybrid method

International Nuclear Information System (INIS)

Mahapatra, S.K.; Dandapat, B.K.; Sarkar, A.

2006-01-01

The current study addresses the mathematical modeling aspects of coupled conductive and radiative heat transfer in the presence of absorbing, emitting and isotropic scattering gray medium within two-dimensional square enclosure. A blended method where the concepts of modified differential approximation employed by combining discrete ordinate method and spherical harmonics method, has been developed for modeling the radiative transport equation. The gray participating medium is bounded by isothermal walls of two-dimensional enclosure which are considered to be opaque, diffuse and gray. The effect of various influencing parameters i.e., radiation-conduction parameter, surface emissivity, single scattering albedo and optical thickness has been illustrated. The adaptability of the present method has also been addressed

TOMS Absorbing Aerosol Index

Data.gov (United States)

Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

21 CFR 880.6025 - Absorbent tipped applicator.

Science.gov (United States)

2010-04-01

... stick. The device is used to apply medications to, or to take specimens from, a patient. (b...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Miscellaneous Devices § 880.6025 Absorbent tipped applicator. (a) Identification. An absorbent tipped applicator is a...

Wideband aural acoustic absorbance predicts conductive hearing loss in children.

Science.gov (United States)

Keefe, Douglas H; Sanford, Chris A; Ellison, John C; Fitzpatrick, Denis F; Gorga, Michael P

2012-12-01

This study tested the hypothesis that wideband aural absorbance predicts conductive hearing loss (CHL) in children medically classified as having otitis media with effusion. Absorbance was measured in the ear canal over frequencies from 0.25 to 8 kHz at ambient pressure or as a swept tympanogram. CHL was defined using criterion air-bone gaps of 20, 25, and 30 dB at octaves from 0.25 to 4 kHz. A likelihood-ratio predictor of CHL was constructed across frequency for ambient absorbance, and across frequency and pressure for absorbance tympanometry. Performance was evaluated at individual frequencies and for any frequency at which a CHL was present. Absorbance and conventional 0.226-kHz tympanograms were measured in children of age three to eight years with CHL and with normal hearing. Absorbance was smaller at frequencies above 0.7 kHz in the CHL group than the control group. Based on the area under the receiver operating characteristic curve, wideband absorbance in ambient and tympanometric tests were significantly better predictors of CHL than tympanometric width, the best 0.226-kHz predictor. Accuracies of ambient and tympanometric wideband absorbance did not differ. Absorbance accurately predicted CHL in children and was more accurate than conventional 0.226-kHz tympanometry.

An absorbing microwave micro-solid-phase extraction device used in non-polar solvent microwave-assisted extraction for the determination of organophosphorus pesticides

Energy Technology Data Exchange (ETDEWEB)

Wang Ziming, E-mail: wangziming@jlu.edu.cn [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhao Xin; Xu Xu; Wu Lijie; Su Rui; Zhao Yajing; Jiang Chengfei; Zhang Hanqi [College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Ma Qiang [Chinese Academy of Inspection and Quarantine, Beijing 100123 (China); Lu Chunmei [College of Technology Center, Jilin Entry-Exit Inspection and Quarantine Bureau, Changchun 130062 (China); Dong Deming [College of Environment and Resources, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

2013-01-14

Highlights: Black-Right-Pointing-Pointer An absorbing microwave {mu}-SPE device packed with activated carbon was used. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to enrich the analytes. Black-Right-Pointing-Pointer Absorbing microwave {mu}-SPE device was made and used to heat samples directly. Black-Right-Pointing-Pointer MAE-{mu}-SPE was applied to the extraction of OPPs with non-polar solvent only. - Abstract: A single-step extraction-cleanup method, including microwave-assisted extraction (MAE) and micro-solid-phase extraction ({mu}-SPE), was developed for the extraction of ten organophosphorus pesticides in vegetable and fruit samples. Without adding any polar solvent, only one kind of non-polar solvent (hexane) was used as extraction solvent in the whole extraction step. Absorbing microwave {mu}-SPE device, was prepared by packing activated carbon with microporous polypropylene membrane envelope, and used as not only the sorbent in {mu}-SPE, but also the microwave absorption medium. Some experimental parameters effecting on extraction efficiency was investigated and optimized. 1.0 g of sample, 8 mL of hexane and three absorbing microwave {mu}-SPE devices were added in the microwave extraction vessel, the extraction was carried out under 400 W irradiation power at 60 Degree-Sign C for 10 min. The extracts obtained by MAE-{mu}-SPE were directly analyzed by GC-MS without any clean-up process. The recoveries were in the range of 93.5-104.6%, and the relative standard deviations were lower than 8.7%.

Proposal concerning the absorbed dose conversion factor

Energy Technology Data Exchange (ETDEWEB)

Shiragai, A [National Inst. of Radiological Sciences, Chiba (Japan)

1978-03-01

New definitions of the absorbed dose conversion factors Csub(lambda) and Csub(E) are proposed. The absorbed dose in water is given by the product of absorbed dose conversion factor, exposure calibration factor, ionisation chamber reading, cap displacement correction factor and perturbation correction factor. At exposure calibration the material of the build-up cap must be the same as that of the chamber wall. An ionisation chamber of which the wall material is water-equivalent or air-equivalent may be used. In the latter case the wall must be thin. For these two cases absorbed dose conversion factors are introduced and it is recommended that either of the two sets should be adopted. Furthermore, if the chamber wall is neither water- nor air-equivalent, the factor by which these currently defined values should be multiplied is also given: again the wall must be thin. The ICRU definitions of Csub(lambda) and Csub(E) are inconsistent, as recently pointed out, while the definitions presented here are consistent.

The MuCool/MICE LH2 Absorber Program

International Nuclear Information System (INIS)

Cummings, Mary Anne

2004-01-01

Hydrogen absorber R and D for the MuCool Collaboration is actively pushing ahead on two parallel and complementary fronts. The continuing LH2 engineering and technical developments by the MuCool group, conducted by ICAR institutions (NIU, IIT and UIUC), the University of Mississippi and Oxford University in cooperation with Fermilab, are summarized here, including plans for the first tests of an absorber prototype from Osaka University and KEK cooled by internal convection at the newly constructed FNAL MuCool Test Area (MTA). Designs for the high-power test of another absorber prototype (employing external heat exchange) are complete and the system will be installed by summer 2004. A convection-cooled absorber design is being developed for the approved MICE cooling demonstration at Rutherford Appleton Laboratory

[Study on absorbing volatile oil with mesoporous carbon].

Science.gov (United States)

Yan, Hong-mei; Jia, Xiao-bin; Zhang, Zhen-hai; Sun, E; Yang Nan

2014-11-01

Clove oil and turmeric oil were absorbed by mesoporous carbon. The absorption ratio of mesoporous carbon to volatile oil was optimized with the eugenol yield and curcumol yield as criteria Curing powder was characterized by scanning electron microscopy (SEM) and differential scanning calorietry (DSC). The effects of mesoporous carbon on dissolution in vitro and thermal stability of active components were studied. They reached high adsorption rate when the absorption ratio of mesoporous carbon to volatile oil was 1:1. When volatile oil was absorbed, dissolution rate of active components had a little improvement and their thermal stability improved after volatile oil was absorbed by the loss rate decreasing more than 50%. Absorbing herbal volatile oil with mesoporous carbon deserves further studying.

Influence of the medium on the reaction rate of the t-butoxyl radical with iron(II)

International Nuclear Information System (INIS)

Mihaljevic, B.; Razem, D.

2002-01-01

Complete text of publication follows. Tert-butoxyl radicals (t-BuO.) were generated by homolytic photodecomposition of di-tert-butylperoxide using ruby laser flashes at 347 nm. The reaction of t-BuO. radicals with Fe 2+ was studied under pseudo-first order conditions. The quantum yield Φ(Fe 3+ ) was determined by measuring the absorbance of Fe 3+ ion as [FeCl] 2+ complex at 360 nm 2 μs after the flash. According to the equation derived from the reaction scheme, the rate constant k 3 was obtained from the relative rate constant k r (k r =k 0 /k 3 ) and the value of k 0 ; the latter refers to the overall rate of the competing disappearance of t-BuO. radicals from the system (reaction 2), including the highest contribution of β-cleavage. The rate constant k 0 was determined using diphenylmethanol instead of Fe 2+ . The known rate constant of the reaction of t-BuO. radical with diphenylmethanol giving ketyl radicals (6.9 x 10 6 dm 3 mol -1 s -1 ) was applied. The quantum yield of ketyl radicals was determined by measuring the maximum of absorbance at 535 nm. At acid concentration of 0.023 mol dm -3 HCl the rate constant k 3 = 3.4 x 10 8 dm 3 mol -1 s -1 was determined. The relative rate constant increased with an increase of the hydrochloric acid concentration which has been ascribed to the lower stability of t-BuO. radical at higher acidity of the medium. The effect of polarity of the medium on the reaction rate was also determined. Decreasing k 3 in media of increasing polarity were explained by increasing of the β-scission rate of t-BuO. radical with increasing polarity of the medium

Diesel NO{sub x} reduction by plasma-regenerated absorbent beds

Science.gov (United States)

Wallman, P.H.; Vogtlin, G.E.

1998-02-10

Reduction of NO{sub x} from diesel engine exhaust by use of plasma-regenerated absorbent beds is described. This involves a process for the reduction of NO{sub x} and particulates from diesel engines by first absorbing NO{sub x} onto a solid absorbent bed that simultaneously acts as a physical trap for the particulate matter, and second regenerating said solid absorbent by pulsed plasma decomposition of absorbed NO{sub x} followed by air oxidation of trapped particulate matter. The absorbent bed may utilize all metal oxides, but the capacity and the kinetics of absorption and desorption vary between different materials, and thus the composition of the absorbent bed is preferably a material which enables the combination of NO{sub x} absorption capability with catalytic activity for oxidation of hydrocarbons. Thus, naturally occurring or synthetically prepared materials may be utilized, particularly those having NO{sub x} absorption properties up to temperatures around 400 C which is in the area of diesel engine exhaust temperatures. 1 fig.

Metals and dust in the neutral ISM: the Galaxy, Magellanic Clouds, and damped Lyman-α absorbers

Science.gov (United States)

De Cia, Annalisa

2018-05-01

Context. The presence of dust in the neutral interstellar medium (ISM) dramatically changes the metal abundances that we measure. Understanding the metal content in the neutral ISM, and a direct comparison between different environments, has been hampered to date because of the degeneracy to the observed ISM abundances caused by the effects of metallicity, the presence of dust, and nucleosynthesis. Aims: We study the metal and dust content in the neutral ISM consistently in different environments, and assess the universality of recently discovered sequences of relative abundances. We also intend to assess the validity of [Zn/Fe] as a tracer of dust in the ISM. This has recently been cast into doubt based on observations of stellar abundances, and needs to be addressed before we can safely use it to study the ISM. Methods: In this letter we present a simple comparison of relative abundances observed in the neutral ISM in the Galaxy, the Magellanic Clouds, and damped Lyman-α absorbers (DLAs). The main novelty in this comparison is the inclusion of the Magellanic Clouds. Results: The same sequences of relative abundances are valid for the Galaxy, Magellanic Clouds, and DLAs. These sequences are driven by the presence of dust in the ISM and seem "universal". Conclusions: The metal and dust properties in the neutral ISM appear to follow a similar behaviour in different environments. This suggests that a dominant fraction of the dust budget is built up from grain growth in the ISM depending of the physical conditions and regardless of the star formation history of the system. In addition, the DLA gas behaves like the neutral ISM, at least from a chemical point of view. Finally, despite the deviations in [Zn/Fe] observed in stellar abundances, [Zn/Fe] is a robust dust tracer in the ISM of different environments, from the Galaxy to DLAs.

Analysis of absorbing times of quantum walks

International Nuclear Information System (INIS)

Yamasaki, Tomohiro; Kobayashi, Hirotada; Imai, Hiroshi

2003-01-01

Quantum walks are expected to provide useful algorithmic tools for quantum computation. This paper introduces absorbing probability and time of quantum walks and gives both numerical simulation results and theoretical analyses on Hadamard walks on the line and symmetric walks on the hypercube from the viewpoint of absorbing probability and time

Release of UV-absorbing substances from maize coleoptiles during auxin-, fusicoccin- and acid-mediated elongation growth

International Nuclear Information System (INIS)

Miyamoto, K.; Schopfer, P.

1997-01-01

Isolated cell walls from maize coleoptiles prepared under conditions that preserve the ability for enzymatic hemicellulose autolysis release UV-absorbing substances into the incubation medium in a time-dependent reaction with an optimal rate at pH 6–7. The reaction can be inhibited by low temperature and protein-denaturing treatments, indicating an enzymatic process. Spectroscopic and chromatographic analyses showed that the liberated substances represent a complex mixture of free and bound (alkali-hydrolyzable) phenolic compounds with similar absorption spectra restricted to the range below 300 nm and thus excluding hydroxycinnamic acids from cell-wall esters. A spectroscopically and chromatographically similar mixture of soluble UV-absorbing substances is released if living (abraded) maize coleoptiles or coleoptile segments are incubated in water or buffer, suggesting that insoluble phenolic materials in the cell wall are metabolized also in vivo. This reaction can be promoted by anaerobic conditions and application of fusicoccin whereas auxin had a slightly inhibitory effect. No clear relationship to elongation growth could be demonstrated. We conclude from these results that polymeric phenolic constituents of the cell wall are subject to enzymatic degradation in muro similar to polysaccharide autolysis and that this process is under metabolic control

Studies in medium energy physics

International Nuclear Information System (INIS)

Green, A.; Hoffmann, G.W.; McDonough, J.; Purcell, M.J.; Ray, R.L.; Read, D.E.; Worn, S.D.

1991-12-01

This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

Absorber Materials for Transition-Edge Sensor X-ray Microcalorimeters

Science.gov (United States)

Brown, Ari-David; Bandler, Simon; Brekosky, Regis; Chervenak, James; Figueroa-Feliciano, Enectali; Finkbeiner, Fred; Sadleir, Jack; Iyomoto, Naoko; Kelley, Richard; Kilbourne, Caroline;

Dynamics of a multiple-pulse-driven x-ray laser plasma

International Nuclear Information System (INIS)

Wan, A.S.; Da Silva, L.B.; Moreno, J.C.; Cauble, R.; Celliers, P.; Dalhed, H.E. Jr.; Koch, J.A.; Nilsen, J.

1996-01-01

In this paper we describe experimental and computational studies of multiple-pulse-driven laser plasma, which is the gain medium for a neon-like yttrium x-ray laser. Near-field emission profiles have been measured both with and without reinjection of the x-ray laser photons to couple with the amplifying medium created by later pulses using an external multilayer mirror. From the temporal and spatial evolution of the near-field emission profiles we can examine the pulse-to-pulse variation of the x-ray laser plasma due to changes in the hydrodynamics, laser deposition, and the injecting of x-ray laser photons back into an amplifying x-ray laser plasma. Using a combination of radiation hydrodynamics, atomic kinetics, and ray propagation codes, reasonable agreement has been obtained between simulations and the experimental results. copyright 1996 American Institute of Physics

Non-gray gas radiation effect on mixed convection in lid driven square cavity

Energy Technology Data Exchange (ETDEWEB)

Cherifi, Mohammed, E-mail: production1998@yahoo.fr; Benbrik, Abderrahmane, E-mail: abenbrik@umbb.dz; Laouar-Meftah, Siham, E-mail: laouarmeftah@gmail.com [M’Hamed Bougara University, Faculty of Hydrocarbons and Chemistry, 35000 Boumerdes (Algeria); Lemonnier, Denis, E-mail: denis.lemonnier@ensma.fr [Institut Pprime, CNRS, ENSMA, University of Poitiers, Poitiers Futuroscope (France)

2016-06-02

A numerical study is performed to investigate the effect of non-gray radiation on mixed convection in a vertical two sided lid driven square cavity filled with air-H{sub 2}O-CO{sub 2} gas mixture. The vertical moving walls of the enclosure are maintained at two different but uniform temperatures. The horizontal walls are thermally insulated and considered as adiabatic walls. The governing differential equations are solved by a finite-volume method and the SIMPLE algorithm was adopted to solve the pressure–velocity coupling. The radiative transfer equation (RTE) is solved by the discrete ordinates method (DOM). The spectral line weighted sum of gray gases model (SLW) is used to account for non-gray radiation properties. Simulations are performed in configurations where thermal and shear forces induce cooperating buoyancy forces. Streamlines, isotherms, and Nusselt number are analyzed for three different values of Richardson’s number (from 0.1 to 10) and by considering three different medium (transparent medium, gray medium using the Planck mean absorption coefficient, and non-gray medium assumption).

Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels

Science.gov (United States)

Singh, Meenesh R.; Clark, Ezra L.; Bell, Alexis T.

2015-01-01

Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32–42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0–0.9 V, 0.9–1.95 V, and 1.95–3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices. PMID:26504215

Designing Efficient Solar-Driven Hydrogen Evolution Photocathodes Using Semitransparent MoQxCly(Q = S, Se) Catalysts on Si Micropyramids

KAUST Repository

Ding, Qi

2015-09-21

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Silicon micropyramids with n+pp+ junctions are demonstrated to be efficient absorbers for integrated solar-driven hydrogen production systems enabling significant improvements in both photocurrent and onset potential. When conformally coated with MoSxCly, a catalyst that has excellent catalytic activity and high optical transparency, the highest photocurrent density for Si-based photocathodes with earth-abundant catalysts is achieved.

Airborne and total gamma absorbed dose rates at Patiala - India

International Nuclear Information System (INIS)

Tesfaye, Tilahun; Sahota, H.S.; Singh, K.

1999-01-01

The external gamma absorbed dose rate due to gamma rays originating from gamma emitting aerosols in air, is compared with the total external gamma absorbed dose rate at the Physics Department of Punjabi University, Patiala. It has been found out that the contribution, to the total external gamma absorbed dose rate, of radionuclides on particulate matter suspended in air is about 20% of the overall gamma absorbed dose rate. (author)

Effects and mechanistic aspects of absorbing organic compounds by coking coal.

Science.gov (United States)

Ning, Kejia; Wang, Junfeng; Xu, Hongxiang; Sun, Xianfeng; Huang, Gen; Liu, Guowei; Zhou, Lingmei

2017-11-01

Coal is a porous medium and natural absorbent. It can be used for its original purpose after adsorbing organic compounds, its value does not reduce and the pollutants are recycled, and then through systemic circulation of coking wastewater zero emissions can be achieved. Thus, a novel method of industrial organic wastewater treatment using adsorption on coal is introduced. Coking coal was used as an adsorbent in batch adsorption experiments. The quinoline, indole, pyridine and phenol removal efficiencies of coal adsorption were investigated. In addition, several operating parameters which impact removal efficiency such as coking coal consumption, oscillation contact time, initial concentration and pH value were also investigated. The coking coal exhibited properties well-suited for organics' adsorption. The experimental data were fitted to Langmuir and Freundlich isotherms as well as Temkin and Redlich-Peterson (R-P) models. The Freundlich isotherm model provided reasonable models of the adsorption process. Furthermore, the purification mechanism of organic compounds' adsorption on coking coal was analysed.

Absorbed dose rate meter for β-ray

International Nuclear Information System (INIS)

Bingo, K.

1977-01-01

The absorbed dose of β-ray depends on the energy of β-rays and the epidermal thickness of tissue in interest. In order to measure the absorbed dose rate at the interested tissue directly, the ratio of counting rate to absorbed dose should be constant independent of β-ray energy. In this purpose, a thin plastic scintillator was used as a detector with a single channel analyzer. The pulse height distribution, obtained using the scintillator whose thickness is less than the range of β-rays, shows a peak at a particular pulse height depending on the thickness of scintillator used. This means an increase of the number of pulses at lower pulse height. The lower level of discrimination and window width of the single channel analyzer are chosen according to the epidermal thickness of the tissue. In the experiment, scintillators of 0.5, 1, 2, 3, 5 and 10 mm thick were tested. It was found that desirable pulse height distribution, to obtain a constant dose sensitivity, could be obtained using the 2 mm thick scintillator. The sensitivity of the absorbed dose rate meter is constant within +-15% for β-ray with maximum energy from 0.4 to 3.5 MeV, when the absorbed dose rate for skin (epidermal thickness 7mg/cm 2 ) is measured. In order to measure the dose rate for a hand (epithermal thickness 40mg/cm 2 ) the lower level of discrimination is changed to be higher and at the same time the window width is also changed. Combining these techniques, one can get an absorbed dose rate meter for the tissue dose of various thickness, which has the constant dose sensitivity within +-15% for β-rays with maximum energy from 0.4 to 3.5 MeV

An Absorbing Look at Terry-Cloth Towels

Science.gov (United States)

Moyer, Richard; Everett, Susan

2010-01-01

This article describes a lesson where students explore the absorbency of several towels with different weaves and weights. The lesson follows the 5E learning-cycle model and incorporates engineering in the sense of product testing with a focus on the relationship between the weave of a towel and its absorbency. The National Science Education…

A Wedge Absorber Experiment at MICE

Energy Technology Data Exchange (ETDEWEB)

Neuffer, David [Fermilab; Mohayai, Tanaz [IIT, Chicago; Rogers, Chris [Rutherford; Snopok, Pavel [IIT, Chicago; Summers, Don [Mississippi U.

2017-05-01

Emittance exchange mediated by wedge absorbers is required for longitudinal ionization cooling and for final transverse emittance minimization for a muon collider. A wedge absorber within the MICE beam line could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders, as well as configurations for low-energy muon sources. Parameters for this test are explored in simulation and possible experimental configurations with simulated results are presented.

UV-absorbing compounds in subarctic herbarium bryophytes

Energy Technology Data Exchange (ETDEWEB)

Huttunen, S. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)]. E-mail: satu.huttunen@oulu.fi; Lappalainen, N.M. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland); Turunen, J. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)

2005-01-01

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A{sub 280-320nm}) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time.

UV-absorbing compounds in subarctic herbarium bryophytes

International Nuclear Information System (INIS)

Huttunen, S.; Lappalainen, N.M.; Turunen, J.

2005-01-01

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A 280-320nm ) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time

Induced absorption and stimulated emission in a driven two-level atom

International Nuclear Information System (INIS)

Mavroyannis, C.

1992-01-01

We have considered the induced processes that occur in a driven two-level atom, where a laser photon is absorbed and emitted by the ground and by the excited states of the atom, respectively. In the low-intensity limit of the laser field, the induced spectra arising when a laser photon is absorbed by the ground state of the atom consist of two peaks describing induced absorption and stimulated-emission processes, respectively, where the former prevails over the latter. Asymmetry of the spectral lines occurs at off-resonance and its extent depends on the detuning of the laser field. The physical. process where a laser photon is emitted by the excited state is the reverse of that arising from the absorption of a laser photon by the ground state of the atom. The former differs from the latter in that the emission of a laser photon by the excited state occurs in the low frequency regime and that the stimulated-emission process prevails over that of the induced absorption. In this case, amplification of ultrashort pulses is likely to occur without the need of population inversion between the optical transitions. The computed spectra are graphically presented and discussed. (author)

Triplet-triplet energy transfer from a UV-A absorber butylmethoxydibenzoylmethane to UV-B absorbers.

Science.gov (United States)

Kikuchi, Azusa; Oguchi-Fujiyama, Nozomi; Miyazawa, Kazuyuki; Yagi, Mikio

2014-01-01

The phosphorescence decay of a UV-A absorber, 4-tert-butyl-4'-methoxydibenzolymethane (BMDBM) has been observed following a 355 nm laser excitation in the absence and presence of UV-B absorbers, 2-ethylhexyl 4-methoxycinnamate (octyl methoxycinnamate, OMC) and octocrylene (OCR) in ethanol at 77 K. The lifetime of the lowest excited triplet (T1) state of BMDBM is significantly reduced in the presence of OMC and OCR. The observed quenching of BMDBM triplet by OMC and OCR suggests that the intermolecular triplet-triplet energy transfer occurs from BMDBM to OMC and OCR. The T1 state of OCR is nonphosphorescent or very weakly phosphorescent. However, we have shown that the energy level of the T1 state of OCR is lower than that of the enol form of BMDBM. Our methodology of energy-donor phosphorescence decay measurements can be applied to the study of the triplet-triplet energy transfer between UV absorbers even if the energy acceptor is nonphosphorescent. In addition, the delayed fluorescence of BMDBM due to triplet-triplet annihilation was observed in the BMDBM-OMC and BMDBM-OCR mixtures in ethanol at 77 K. Delayed fluorescence is one of the deactivation processes of the excited states of BMDBM under our experimental conditions. © 2013 The American Society of Photobiology.

Effect of inclusions' distribution on microwave absorbing properties of composites

International Nuclear Information System (INIS)

Qin, Siliang; Wang, Qingguo; Qu, Zhaoming

2013-01-01

Effect of inclusions' spatial distributions on the permeability and permittivity of composites is studied using the generalized Maxwell-Garnett equations. The result indicates that inclusions' orientation distribution can increase the longitudinal electromagnetic parameters. For inclusions' random and orientation distribution, single and three-layer absorbers are designed and optimized using genetic algorithm. The result shows that under a given absorbing requirement, absorber with inclusions' orientation distribution is lighter and thinner than absorber with inclusions' random distribution.

Actual behaviour of a ball vibration absorber

Czech Academy of Sciences Publication Activity Database

Pirner, Miroš

2002-01-01

Roč. 90, č. 8 (2002), s. 987-1005 ISSN 0167-6105 R&D Projects: GA ČR(CZ) GV103/96/K034 Institutional support: RVO:68378297 Keywords : TV towers * wind-excited vibrations * vibration absorbers * pendulum absorber Subject RIV: JM - Building Engineering Impact factor: 0.513, year: 2002 http://www.sciencedirect.com/science/article/pii/S0167610502002155#

Physically absorbable reagents-collectors in elementary flotation

Energy Technology Data Exchange (ETDEWEB)

S.A. Kondrat' ev; I.G. Bochkarev [Russian Academy of Sciences, Novosibirsk (Russian Federation). Institute of Mining

2007-09-15

Based on the reviewed researches held at the Institute of Mining, Siberian Branch, Russian Academy of Sciences, the effect of physically absorbable reagents-collectors on formation of a flotation complex and its stability in turbulent pulp flows in flotation machines of basic types is considered. The basic requirements for physically absorbable reagents-collectors at different flotation stages are established.

Absorber transmissivities in 57Fe Moessbauer spectroscopy

International Nuclear Information System (INIS)

Ballet, O.

1985-01-01

Some useful relations are derived for the polarization dependent optical index of 57 Fe Moessbauer absorbers. Real rotation matrices are extensively used and, besides wave-direction dependence, their properties simplify also the treatment of texture and f-anisotropy. The derivation of absorber transmissivities from the optical index is discussed with a special emphasis on line overlapping. (Auth.)

Absorbed doses profiles vs Synovia tissue depth for the Y-90 and P-32 used in radiosynoviortesis treatment

International Nuclear Information System (INIS)

Torres B, M.B.; Ayra P, F.E.; Garcia R, E.; Cornejo D, N.; Yoriyaz, H.

2006-01-01

The radiosynoviortesis treatment has been used during more of 40 years as an alternative to the chemical and surgical synovectomy to alleviate the pain and to reduce the inflammation in suffered patients of rheumatic arthropathies, haemophilic arthropathies and other articulation disorders. It consists on the injection of radioactive isotopes inside a synovial cavity. For to evaluate the dosimetry of the radiosynoviortesis treatment is of great interest to know the absorbed dose in the volume of the target (synovia). The precise calculation of the absorbed dose in the inflamed synovia it is difficult, for numerous reasons, since the same one will depend on the thickness of the synovial membrane, the size of the articular space, the structure of the synovial membrane, the distribution in the articulation, the nature of the articular liquid, etc. Also the presence of the bone and the articular cartilage, components also of the articulation, it even complicated more the calculations. The method used to evaluate the dosimetry in radioactive synovectomy is known as the Monte Carlo method. The objective of our work consists on estimating with the Monte Carlo code MCNP4B the absorbed dose of the Y-90 and the P-32 in the depth of the synovial tissue. The results are presented as absorbed dose for injected millicurie (Gy/mCi) versus depth of synovial tissue. The simulation one carries out keeping in mind several synovia areas, of 50 cm 2 to 250 cm 2 keeping in mind three states of progression of the illness. Those obtained values of absorbed dose using the MCNP4B code will allow to introduce in our country an optimized method of dose prescription to the patient, to treat the rheumatic arthritis in medium and big articulations using the Y-90 and the P-32, eliminating the fixed doses and fixed radionuclides for each articulation like it happens in many clinics of Europe, as well as the empiric doses. (Author)

Capacity modulation of an inverter-driven multi-air conditioner using electronic expansion valves

International Nuclear Information System (INIS)

Choi, J.M.; Kim, Y.C.

2003-01-01

An inverter-driven multi-air conditioner provides the benefits of comfort, energy conservation and easy maintenance. Recently, the multi-air conditioner has been employed in small and medium-sized buildings. However, the performance data and control algorithm for multi-air conditioners are limited in literature due to complicated system parameters and operating conditions. In the present study, the performance of an inverter-driven multi-air conditioner having two indoor units with electronic expansion valves (EEV) was measured by varying indoor loads, EEV opening, and compressor speed. Based on the experimental results, the operating characteristics and capacity modulation of the inverter-driven multi-air conditioner are discussed. As a result, it is suggested that the superheats for both indoor units have to be maintained around 4 o C by utilizing the EEVs in this system, and consequently, the compressor speed needs to be adjusted to provide optimum cooling capacity for each indoor unit

Inferring absorbing organic carbon content from AERONET data

Science.gov (United States)

Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

2011-01-01

Black carbon, light-absorbing organic carbon (often called "brown carbon") and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light-absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South America and Africa are relatively high (about 15-20 mg m-2 during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 mg m-2 during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

A Stretchable Electromagnetic Absorber Fabricated Using Screen Printing Technology.

Science.gov (United States)

Jeong, Heijun; Lim, Sungjoon

2017-05-21

A stretchable electromagnetic absorber fabricated using screen printing technology is proposed in this paper. We used a polydimethylsiloxane (PDMS) substrate to fabricate the stretchable absorber since PDMS exhibits good dielectric properties, flexibility, and restoring capabilities. DuPont PE872 (DuPont, Wilmington, CT, USA), a stretchable silver conductive ink, was used for the screen printing technique. The reflection coefficient of the absorber was measured using a vector network analyzer and a waveguide. The proposed absorber was designed as a rectangular patch unit cell, wherein the top of the unit cell acted as the patch and the bottom formed the ground. The size of the patch was 8 mm × 7 mm. The prototype of the absorber consisted of two unit cells such that it fits into the WR-90 waveguide (dimensions: 22.86 mm × 10.16 mm) for experimental measurement. Before stretching the absorber, the resonant frequency was 11 GHz. When stretched along the x -direction, the resonant frequency shifted by 0.1 GHz, from 11 to 10.9 GHz, demonstrating 99% absorption. Furthermore, when stretched along the y -direction, the resonant frequency shifted by 0.6 GHz, from 11 to 10.4 GHz, demonstrating 99% absorption.

Energy deposition studies for the LBNE beam absorber

International Nuclear Information System (INIS)

Rakhno, Igor L.; Mokhov, Nikolai V.; Tropin, Igor S.

2015-01-01

Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system - all with corresponding radiation shielding - was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options. (authors)

A randomised controlled trial of absorbable versus non-absorbable sutures for skin closure after open carpal tunnel release.

LENUS (Irish Health Repository)

Theopold, C

2012-05-01

We compared the aesthetic outcome of scars after closure of open carpal tunnel incisions with either absorbable 4-0 Vicryl Rapide or non-absorbable 4-0 Novafil. Patients were recruited in a randomized controlled trial and scars were scored at 6 weeks using a modified Patient and Observer Scar Assessment Scale. Scores demonstrated differences only for pain, vascularity and cross-hatching between both groups, though none of these were statistically significant. The dissolving and falling out of Vicryl Rapide was significantly more comfortable than removal of 4-0 Novafil sutures, assessed on a numerical analogue scale. There was no difference in infection rate between both study groups, supporting overall the use of Vicryl Rapide for the closure of palmar hand incisions, in light of the convenience and cost savings associated with absorbable sutures.

Vibration mitigation for in-wheel switched reluctance motor driven electric vehicle with dynamic vibration absorbing structures

Science.gov (United States)

Qin, Yechen; He, Chenchen; Shao, Xinxin; Du, Haiping; Xiang, Changle; Dong, Mingming

2018-04-01

This paper presents a new approach for vibration mitigation based on a dynamic vibration absorbing structure (DVAS) for electric vehicles (EVs) that use in-wheel switched reluctance motors (SRMs). The proposed approach aims to alleviate the negative effects of vibration caused by the unbalanced electromagnetic force (UMEF) that arises from road excitations. The analytical model of SRMs is first formulated using Fourier series, and then a model of the coupled longitudinal-vertical dynamics is developed taking into consideration the external excitations consisting of the aerodynamic drag force and road unevenness. In addition, numerical simulations for a conventional SRM-suspension system and two novel DVASs are carried out for varying road levels specified by ISO standards and vehicle velocities. The results of the comparison reveal that a 35% improvement in ride comfort, 30% improvement of road handling, and 68% improvement in air gap between rotor and stator can be achieved by adopting the novel DVAS compared to the conventional SRM-suspension system. Finally, multi-body simulation (MBS) is performed using LMS Motion to validate the feasibility of the proposed DVAS. Analysis of the results shows that the proposed method can augment the effective application of SRMs in EVs.

Optimal design of MR shock absorber and application to vehicle suspension

International Nuclear Information System (INIS)

Nguyen, Quoc-Hung; Choi, Seung-Bok

2009-01-01

This paper presents an optimal design of a magnetorheological (MR) shock absorber based on finite element analysis. The MR shock absorber is constrained in a specific volume and the optimization problem identifies geometric dimensions of the shock absorber that minimize a multi-objective function. The objective function is proposed by considering the damping force, dynamic range and the inductive time constant of the shock absorber. After describing the configuration of the MR shock absorber, a quasi-static modeling of the shock absorber is performed based on the Bingham model of an MR fluid. The initial geometric dimensions of the shock absorber are then determined based on the assumption of constant magnetic flux density throughout the magnetic circuit. The objective function of the optimization problem is derived based on the solution of the initial shock absorber. An optimization procedure using a golden-section algorithm and a local quadratic fitting technique is constructed via a commercial finite element method parametric design language. Using the developed optimization tool, optimal solutions of the MR shock absorber, which is constrained in a specific cylindrical volume defined by its radius and height, are determined. Subsequently, a quarter-car suspension model with the optimized MR shock absorber is formulated and the vibration control performance of the suspension is evaluated under bump and sinusoidal road conditions

Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052

Energy Technology Data Exchange (ETDEWEB)

Sun, Luming; Zhou, Hongyan; Ji, Tuo; Jiang, Peng; Liu, Bo; Pan, Xiang; Shi, Xiheng; Zhang, Shaohua [Polar Research Institute of China, 451 Jinqiao Road, Shanghai (China); Liu, Wenjuan; Wang, Jianguo [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan (China); Wang, Tinggui; Yang, Chenwei [Department of Astronomy, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui (China); Miller, Lauren P., E-mail: lmsun@mail.ustc.edu.cn [Lehigh University, 27 Memorial Drive West, Bethlehem, PA 18015 (United States)

2017-04-01

In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ∼700 and ∼1400 km s{sup −1} relative to the quasar rest frame. The former component shows rare Balmer absorption, which is an indicator of high-density absorbing gas; thus, the quasar is worth follow-up spectroscopic observations. Our follow-up optical and near-infrared spectra using MMT, YFOSC, TSpec, and DBSP reveal that the strengths of the absorption lines vary for both components, while the velocities do not change. We reproduce all of the spectral data by assuming that only the ionization state of the absorbing gas is variable and that all other physical properties are invariable. The variation of ionization is consistent with the variation of optical continuum from the V -band light curve. Additionally, we cannot interpret the data by assuming that the variability is due to a movement of the absorbing gas. Therefore, our analysis strongly indicates that the absorption-line variability in LBQS 1206+1052 is photoionization driven. As shown from photoionization simulations, the absorbing gas with blueshift velocity of ∼700 km s{sup −1} has a density in the range of 10{sup 9} to 10{sup 10} cm{sup −3} and a distance of ∼1 pc, and the gas with blueshift velocity of ∼1400 km s{sup −1} has a density of 10{sup 3} cm{sup −3} and a distance of ∼1 kpc.

Evaluation of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh in a porcine model of ventral hernia repair.

Science.gov (United States)

Scott, Jeffrey R; Deeken, Corey R; Martindale, Robert G; Rosen, Michael J

2016-09-01

The objective of this study was to evaluate the mechanical and histological properties of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh (Phasix™ ST) compared to partially absorbable (Ventralight™ ST), fully absorbable (Phasix™), and biologically derived (Strattice™) meshes in a porcine model of ventral hernia repair. Bilateral abdominal surgical defects were created in twenty-four Yucatan pigs, repaired with intraperitoneal (Phasix™ ST, Ventralight™ ST) or retromuscular (Phasix™, Strattice™) mesh, and evaluated at 12 and 24 weeks (n = 6 mesh/group/time point). Prior to implantation, Strattice™ demonstrated significantly higher (p weeks, mesh/repair strength was significantly greater than NAW (p weeks (p > 0.05). Phasix™ mesh/repair strength was significantly greater than Strattice™ (p weeks, and Ventralight™ ST mesh/repair strength was significantly greater than Phasix™ ST mesh (p weeks. At 12 and 24 weeks, Phasix™ ST and Ventralight™ ST were associated with mild inflammation and minimal-mild fibrosis/neovascularization, with no significant differences between groups. At both time points, Phasix™ was associated with minimal-mild inflammation/fibrosis and mild neovascularization. Strattice™ was associated with minimal inflammation/fibrosis, with minimal neovascularization at 12 weeks, which increased to mild by 24 weeks. Strattice™ exhibited significantly less neovascularization than Phasix™ at 12 weeks and significantly greater inflammation at 24 weeks due to remodeling. Phasix™ ST demonstrated mechanical and histological properties comparable to partially absorbable (Ventralight™ ST) and fully resorbable (Phasix™) meshes at 12 and 24 weeks in this model. Data also suggest that fully absorbable meshes with longer-term resorption profiles may provide improved mechanical and histological properties compared to biologically derived scaffolds.

Are bio-absorbable stents the future of SFA treatment?

Science.gov (United States)

Peeters, P; Keirse, K; Verbist, J; Deloose, K; Bosiers, M

2010-02-01

Several limitations inherent to the implantation of a metallic device, such as the occurrence of in-stent re-stenosis, in an arterial lumen intuitively explain the interest for developing bio-absorbable stents. Two main types of bio-absorbable stents currently exist: polymer stents and metallic stents. To date, no studies with bio-absorbable stents have been conducted in the superficial femoral artery (SFA). Because of their strut thickness and lack of radial force, polymer stents are no good candidates for endovascular use. Absorbable metal stents (AMS) do have the potential to perform well for artery treatment, although current evidence from in-human coronary and infrapopliteal studies yield unsatisfactory results. Drastic technological improvements are mandatory before AMS can be considered for every day practice. Yet, it is our belief that further development of other metal and non-metal bio-absorbable stents, with or without drug-coating, may lead to the creation of the ultimate SFA stent.

New Technology in Hydrogen Absorbers for Muon Cooling Channels

CERN Document Server

Cummings, M A C

2005-01-01

Ionization cooling is the only technique fast enough to cool and focus muons for neutrino factories and muon colliders, and hydrogen is the optimal material for maximum cooling and minimal multiple scattering. Liquid hydrogen absorber R&D for the Muon Collaboration has proceeded on parallel and complementary fronts. The continuing LH2 absorber engineering and technical developments by the MuCool group conducted by ICAR* institutions (NIU, IIT and UIUC), the University of Mississippi and Oxford University, in cooperation with Fermilab, will be summarized, including results from the first hydrogen absorber tests at the newly constructed FNAL Mucool Test Area (MTA). The program includes designs for the high-powered test of an absorber prototype (external heat exchange) at the MTA which are nearing completion to be installed by summer 2005, an alternative absorber design (internal heat exchange) being finalized for the approved cooling experiment (MICE) at Rutherford-Appleton Laboratory, and a novel idea for ...

Absorber performance of a water/lithium-bromide absorption chiller

International Nuclear Information System (INIS)

Xie Guozhen; Sheng Guogang; Bansal, Pradeep Kumar; Li, Guang

2008-01-01

An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure

Optically Modulated Multiband Terahertz Perfect Absorber

DEFF Research Database (Denmark)

Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue

2014-01-01

response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented....... Utilizing photo-excited free carriers in silicon padsplaced in the capacitive gaps of split ring resonators, a dynamically modu-lated perfect absorber is designed and fabricated to operate in reflection.Large modulation depth (38% and 91%) in two absorption bands (with 97%and 92% peak absorption...

Preparation and characterization of super absorbent polymer from sugarcane bagasse

International Nuclear Information System (INIS)

Wiwien Andriyanti; Suyanti; Ngasifudin

2012-01-01

Sugarcane bagasse is a source of biomass which large enough numbers and has not been fully exploited. At this time has developed a super absorbent polymer material of sugarcane bagasse that can absorb water up to several times of its own weight and keep this water. Super absorbent polymers can be used as a soil conditioner that can be used as an absorber and storage of ground water, the giver of nutrients for plants, and can improve soil properties. The purpose of this study is to make and characterization of super absorbent polymer (PCS) from sugarcane bagasse. Preparation of super absorbent polymers (PCS) has been done by grafting method using ionizing radiation from Electron Beam Engineering (MBE) 350 mA keV/10. Irradiation process carried out with a dose variation of 20, 35, and 50 kGy. Increasing doses of radiation will increase the percentage fraction of transplantation (grafting) and the fraction of water absorption ability (swelling ratio). (author)

Design of broadband absorber using 2-D materials for thermo-photovoltaic cell application

Science.gov (United States)

Agarwal, Sajal; Prajapati, Y. K.

2018-04-01

Present study is done to analyze a nano absorber for thermo-photovoltaic cell application. Optical absorbance of two-dimensional materials is exploited to achieve high absorbance. It is found that few alternating layers of graphene/transition metal dichalcogenide provide high absorbance of electromagnetic wave in visible as well as near infrared region. Four transition metal dichalcogenides are considered and found that most of these provide perfect absorbance for almost full considered wavelength range i.e. 200-1000 nm. Demonstrated results confirm the extended operating region and improved absorbance of the proposed absorber in comparison to the existing absorbers made of different materials. Further, absorber performance is improved by using thin layers of gold and chromium. Simple geometry of the proposed absorber also ensures easy fabrication.

Magnetic-field-driven localization of light in a cold-atom gas.

Science.gov (United States)

Skipetrov, S E; Sokolov, I M

2015-02-06

We discover a transition from extended to localized quasimodes for light in a gas of immobile two-level atoms in a magnetic field. The transition takes place either upon increasing the number density of atoms in a strong field or upon increasing the field at a high enough density. It has many characteristic features of a disorder-driven (Anderson) transition but is strongly influenced by near-field interactions between atoms and the anisotropy of the atomic medium induced by the magnetic field.

Calculations in the Wheeler-Feynman absorber theory of radiation

International Nuclear Information System (INIS)

Balaji, K.S.

1986-01-01

One dimensional computer aided calculations were done to find the self consistent solutions for various absorber configurations in the context of the Wheeler-Feynman absorber theory, wherein every accelerating charge is assumed to produce a time symmetric combination of advanced and retarded fields. These calculations picked out the so called outerface solution for incomplete absorbers and showed that advanced as well as retarded signals interact with matter in the same manner as in the full retarded theory. Based on these calculations, the Partridge experiment and the Schmidt-Newman experiment were ruled out as tests of the absorber theory. An experiment designed to produce and detect advanced effects is proposed, based on more one-dimensional calculations

Effect of thermal-treatment sequence on sound absorbing and mechanical properties of porous sound-absorbing/thermal-insulating composites

Directory of Open Access Journals (Sweden)

Huang Chen-Hung

2016-01-01

Full Text Available Due to recent rapid commercial and industrial development, mechanical equipment is supplemented massively in the factory and thus mechanical operation causes noise which distresses living at home. In livelihood, neighborhood, transportation equipment, jobsite construction noises impact on quality of life not only factory noise. This study aims to preparation technique and property evaluation of porous sound-absorbing/thermal-insulating composites. Hollow three-dimensional crimp PET fibers blended with low-melting PET fibers were fabricated into hollow PET/low-melting PET nonwoven after opening, blending, carding, lapping and needle-bonding process. Then, hollow PET/low-melting PET nonwovens were laminated into sound-absorbing/thermal-insulating composites by changing sequence of needle-bonding and thermal-treatment. The optimal thermal-treated sequence was found by tensile strength, tearing strength, sound-absorbing coefficient and thermal conductivity coefficient tests of porous composites.

Medium-Energy Nuclear Data Library (MENDLIB): Phase 1

International Nuclear Information System (INIS)

Siciliano, E.R.; Arthur, E.D.

1987-10-01

This document describes an initial step towards the formation of a computerized on-line data library, which would contain published medium-energy experimental data, and which would serve the basic and applied needs of the medium-energy nuclear physics community. The data emphasized in this project will be from measured charged-particle and meson induced nuclear scattering and reactions; an area for which no such data base presently exists. Access to the data will be through a menu-driven program in a user-friendly environment. The project is divided into three phases: Phase 1 involves compilation of Clinton P. Anderson Meson Physics Facility (LAMPF) data from nucleon and pion induced reactions, Phase 2 includes nucleon and pion data from other medium-energy facilities, and Phase 3 includes electron, light-ion, and possibly kaon and anti-nucleon data. The initial goals, the manner in which they would be pursued, and the resources needed to implement Phase 1 (the pilot phase) are discussed in detail. Possible expansion of Phase 1 to attain the envisioned goals of Phase 2 and 3 are briefly outlined. During all stages of the project, input from the community will be sought via the various facility user groups and the American Physical Society Division of Nuclear Physics. It is proposed that the Applied Nuclear Science Group (T-2) of the Los Alamos National Laboratory oversees the development and implementation of this project, and the LAMPF VAX computers be used as the host computers for on-line access

Inferring absorbing organic carbon content from AERONET data

Directory of Open Access Journals (Sweden)

A. Arola

2011-01-01

Full Text Available Black carbon, light-absorbing organic carbon (often called "brown carbon" and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light–absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon levels in biomass burning regions of South America and Africa are relatively high (about 15–20 mg m⁻² during biomass burning season, while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30–35 mg m⁻² during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

Development of advanced boiling water reactor for medium capacity

International Nuclear Information System (INIS)

Kazuo Hisajima; Yutaka Asanuma

2005-01-01

This paper describes a result of development of an Advanced Boiling Water Reactor for medium capacity. 1000 MWe was selected as the reference. The features of the current Advanced Boiling Water Reactors, such as a Reactor Internal Pump, a Fine Motion Control Rod Drive, a Reinforced Concrete Containment Vessel, and three-divisionalized Emergency Core Cooling System are maintained. In addition, optimization for 1000 MWe has been investigated. Reduction in thermal power and application of the latest fuel reduced the number of fuel assemblies, Control Rods and Control Rod Drives, Reactor Internal Pumps, and Safety Relief Valves. The number of Main Steam lines was reduced from four to two. As for the engineered safety features, the Flammability Control System was removed. Special efforts were made to realize a compact Turbine Building, such as application of an in line Moisture Separator, reduction in the number of pumps in the Condensate and Feedwater System, and change from a Turbine-Driven Reactor Feedwater Pump to a Motor-Driven Reactor Feedwater Pump. 31% reduction in the volume of the Turbine Building is expected in comparison with the current Advanced Boiling Water Reactors. (authors)

LINEAR MODEL FOR NON ISOSCELES ABSORBERS.

Energy Technology Data Exchange (ETDEWEB)

BERG,J.S.

2003-05-12

Previous analyses have assumed that wedge absorbers are triangularly shaped with equal angles for the two faces. In this case, to linear order, the energy loss depends only on the position in the direction of the face tilt, and is independent of the incoming angle. One can instead construct an absorber with entrance and exit faces facing rather general directions. In this case, the energy loss can depend on both the position and the angle of the particle in question. This paper demonstrates that and computes the effect to linear order.

Microstructured extremely thin absorber solar cells

DEFF Research Database (Denmark)

Biancardo, Matteo; Krebs, Frederik C

2007-01-01

In this paper we present the realization of extremely thin absorber (ETA) solar cells employing conductive glass substrates functionalized with TiO2 microstructures produced by embossing. Nanocrystalline or compact TiO2 films on Indium doped tin oxide (ITO) glass substrates were embossed by press......In this paper we present the realization of extremely thin absorber (ETA) solar cells employing conductive glass substrates functionalized with TiO2 microstructures produced by embossing. Nanocrystalline or compact TiO2 films on Indium doped tin oxide (ITO) glass substrates were embossed...

Ferrite HOM Absorber for the RHIC ERL

Energy Technology Data Exchange (ETDEWEB)

Hahn,H.; Choi, E.M.; Hammons, L.

2008-10-01

A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

Perpetual pavement – absorbing stress and functional maintenance

Directory of Open Access Journals (Sweden)

Rong Gao

2017-03-01

Full Text Available Perpetual Pavement combines the well documented smoothness and safety advantages of asphalt with an advanced, multi-layer paving design process, that with routine maintenance, extends the useful life of a roadway. Perpetual provides long lasting road and smoothness for the construction purposes. This study has the design key points of perpetual pavement based on the idea of life cycle, which has a new direction for the new highway construction, reconstruction and expansion. First, the structure of long life pavement design is studied to analyze the effect of stress absorbing layer. Second, researches on stress absorbing layer from the aspects of raw materials, mix proportion are implemented. Third, the design index of stress absorbing layer is determined by the shear strength test. The results show that the design idea of composite perpetual pavement can be realized by reasonable design of the stress absorbing layer and carrying out the surface functional maintenance can ensure the pavement to avoid structural damage in the operation stage.

Selective wave-transmitting electromagnetic absorber through composite metasurface

Science.gov (United States)

Sun, Zhiwei; Zhao, Junming; Zhu, Bo; Jiang, Tian; Feng, Yijun

2017-11-01

Selective wave-transmitting absorbers which have one or more narrow transmission bands inside a wide absorption band are often demanded in wireless communication and radome applications for reducing the coupling between different systems, improving anti-jamming capability, and reducing antennas' radar cross section. Here we propose a feasible method that utilizing composite of two metasurfaces with different polarization dependent characteristics, one works as electromagnetic polarization rotator and the other as a wideband polarization dependent electromagnetic wave absorber. The polarization rotator produces a cross polarization output in the wave-transmitting band, while preserves the polarization of the incidence outside the band. The metasurface absorber works for certain linear polarization with a much wider absorption band covering the wave-transmitting frequency. When combining these two metasurfaces properly, the whole structure behaves as a wideband absorber with a certain frequency transmission window. The proposal may be applied in radome designs to reduce the radar cross section of antenna or improving the electromagnetic compatibility in communication devices.

Ultrathin triple-band polarization-insensitive wide-angle compact metamaterial absorber

International Nuclear Information System (INIS)

Shang, Shuai; Yang, Shizhong; Tao, Lu; Yang, Lisheng; Cao, Hailin

2016-01-01

In this study, the design, realization, and characterization of an ultrathin triple-band polarization-insensitive wide-angle metamaterial absorber are reported. The metamaterial absorber comprises a periodic array of modified six-fold symmetric snowflake-shaped resonators with strip spiral line load, which is printed on a dielectric substrate backed by a metal ground plane. It is shown that the absorber exhibits three distinct near-unity absorption peaks, which are distributed across C, X, Ku bands, respectively. Owing to the six-fold symmetry, the absorber is insensitive to the polarization of the incident radiation. In addition, the absorber shows excellent absorption performance over wide oblique incident angles for both transverse electric and transverse magnetic polarizations. Simulated surface current and field distributions at the three absorption peaks are demonstrated to understand the absorption mechanism. Particularly, the absorption modes come from the fundamental and high-order dipole resonances. Furthermore, the experimental verification of the designed absorber is conducted, and the measured results are in reasonable agreement with the simulated ones. The proposed ultrathin (∼0.018λ 0 , λ 0 corresponding to the lowest peak absorption frequency) compact (0.168λ 0 ×0.168λ 0 corresponding to the area of a unit cell) absorber enables potential applications such as stealth technology, electromagnetic interference and spectrum identification.

Gas-phase absorbents for trapping radioactive iodine and iodine compounds

International Nuclear Information System (INIS)

Anon.

1984-01-01

This standard covers granular absorbents (activated carbon, mineral base, polymer, etc.) for use in air and gas treatment systems. The absorbents are used in both thin-bed absorber cells and deep-bed systems. The standard includes docuent list, technical requirements, quality assurance requirements, and preparation for delivery. Test and sampling procedures are given

Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels

Energy Technology Data Exchange (ETDEWEB)

Singh, Meenesh R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint Center for Artificial Photosynthesis, Material Science Division; Clark, Ezra L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint Center for Artificial Photosynthesis, Material Science Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemical & Biomolecular Engineering; Bell, Alexis T. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint Center for Artificial Photosynthesis, Material Science Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemical & Biomolecular Engineering

2015-10-26

Thermodynamic, achievable, and realistic efficiency limits of solar-driven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32–42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0–0.9 V, 0.9–1.95 V, and 1.95–3.5 V, respectively. Achievable solar-to-fuel (STF) efficiencies are determined using ideal double- and triple-junction light absorbers and the electrochemical load curves for CO₂ reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H₂ and CO) and Hythane (H₂ and CH₄) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. Finally, we show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-to-PV area, and that the synthesis of liquid products and C₂H₄ have high profitability indices.

Absorbed energy for radiation crosslinking in stabilized PE systems

International Nuclear Information System (INIS)

Novakovic, Lj.; Gal, O.; Charlesby, A.

1990-01-01

A quantitative consideration on the absorbed energy consumption in various γ-irradiated polyethylene systems is given. On the base of the increased gel dose values for the PE systems containing antioxidant, relative to the gel doses for the pure polymers, the surplus of the absorbed energy due to the presence of the particular antioxidant is calculated. The increasing of the energy consumption in the stabilized systems depends on both the type and the content of the basic polymer. The surplus in the absorbed energy decreases with the radiation dose increasing, reflecting both the diminishing of the antioxidant concentration in the irradiating PE systems and the crosslinking level. The findings can be of interest in the estimation of the absorbed doses for the specific radiation crosslinking processes. (author)

Absorbed energy for radiation crosslinking in stabilized PE systems

Energy Technology Data Exchange (ETDEWEB)

Novakovic, Lj; Gal, O [Institut za Nuklearne Nauke Boris Kidric, Belgrade (Yugoslavia); Charlesby, A

1990-01-01

A quantitative consideration on the absorbed energy consumption in various {gamma}-irradiated polyethylene systems is given. On the base of the increased gel dose values for the PE systems containing antioxidant, relative to the gel doses for the pure polymers, the surplus of the absorbed energy due to the presence of the particular antioxidant is calculated. The increasing of the energy consumption in the stabilized systems depends on both the type and the content of the basic polymer. The surplus in the absorbed energy decreases with the radiation dose increasing, reflecting both the diminishing of the antioxidant concentration in the irradiating PE systems and the crosslinking level. The findings can be of interest in the estimation of the absorbed doses for the specific radiation crosslinking processes. (author).

Absorption systems at z ˜ 2 as a probe of the circum galactic medium: a probabilistic approach

Science.gov (United States)

Mongardi, C.; Viel, M.; D'Odorico, V.; Kim, T.-S.; Barai, P.; Murante, G.; Monaco, P.

2018-05-01

We characterize the properties of the intergalactic medium (IGM) around a sample of galaxies extracted from state-of-the-art hydrodynamical simulations of structure formation in a cosmological volume of 25 Mpc comoving at z ˜ 2. The simulations are based on two different sub-resolution schemes for star formation and supernova feedback: the MUlti-Phase Particle Integrator (MUPPI) scheme and the Effective Model. We develop a quantitative and probabilistic analysis based on the apparent optical depth method of the properties of the absorbers as a function of impact parameter from their nearby galaxies: in such a way we probe different environments from circumgalactic medium (CGM) to low density filaments. Absorbers' properties are then compared with a spectroscopic observational data set obtained from high resolution quasar spectra. Our main focus is on the NCIV - NHI relation around simulated galaxies: the results obtained with MUPPI and the Effective model are remarkably similar, with small differences only confined to regions at impact parameters b = [1 - 3] × rvir. Using {C IV} as a tracer of the metallicity, we obtain evidence that the observed metal absorption systems have the highest probability to be confined in a region of 150-400 kpc around galaxies. Near-filament environments have instead metallicities too low to be probed by present-day telescopes, but could be probed by future spectroscopical studies. Finally we compute {C IV} covering fractions which are in agreement with observational data.

14 CFR 29.475 - Tires and shock absorbers.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 29.475 Section 29.475 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise...

Simulated mixed absorbers and effective atomic numbers for γ ...

Indian Academy of Sciences (India)

Keywords. γ-rays; γ attenuation; simulated mixed absorbers; effective atomic ... We have tried to simulate composite (mixed) absorbers ... Experimental method .... puter, Program manual, Centre for Radiation Research, National Bureau of ...

Semiconductor saturable absorbers for ultrafast THz signals

DEFF Research Database (Denmark)

Hoffmann, Matthias C.; Turchinovich, Dmitry

We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths.......We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths....

Microgravity Investigation of Capillary Driven Imbibition

Science.gov (United States)

Dushin, V. R.; Nikitin, V. F.; Smirnov, N. N.; Skryleva, E. I.; Tyurenkova, V. V.

2018-05-01

The goal of the present paper is to investigate the capillary driven filtration in porous media under microgravity conditions. New mathematical model that allows taking into account the blurring of the front due to the instability of the displacement that is developing at the front is proposed. The constants in the mathematical model were selected on the basis of the experimental data on imbibition into unsaturated porous media under microgravity conditions. The flow under the action of a combination of capillary forces and a constant pressure drop or a constant flux is considered. The effect of capillary forces and the type of wettability of the medium on the displacement process is studied. A criterion in which case the capillary effects are insignificant and can be neglected is established.

Polarization insensitive metamaterial absorber based on E-shaped all-dielectric structure

Directory of Open Access Journals (Sweden)

Liyang Li

2015-03-01

Full Text Available In this paper, we designed a metamaterial absorber performed in microwave frequency band. This absorber is composed of E-shaped dielectrics which are arranged along different directions. The E-shaped all-dielectric structure is made of microwave ceramics with high permittivity and low loss. Within about 1 GHz frequency band, more than 86% absorption efficiency was observed for this metamaterial absorber. This absorber is polarization insensitive and is stable for incident angles. It is figured out that the polarization insensitive absorption is caused by the nearly located varied resonant modes which are excited by the E-shaped all-dielectric resonators with the same size but in the different direction. The E-shaped dielectric absorber contains intensive resonant points. Our research work paves a way for designing all-dielectric absorber.

The anti-bat strategy of ultrasound absorption: the wings of nocturnal moths (Bombycoidea: Saturniidae) absorb more ultrasound than the wings of diurnal moths (Chalcosiinae: Zygaenoidea: Zygaenidae).

Science.gov (United States)

Ntelezos, Athanasios; Guarato, Francesco; Windmill, James F C

2017-01-15

The selection pressure from echolocating bats has driven the development of a diverse range of anti-bat strategies in insects. For instance, several studies have proposed that the wings of some moths absorb a large portion of the sound energy contained in a bat's ultrasonic cry; as a result, the bat receives a dampened echo, and the moth becomes invisible to the bat. To test the hypothesis that greater exposure to bat predation drives the development of higher ultrasound absorbance, we used a small reverberation chamber to measure the ultrasound absorbance of the wings of nocturnal (Bombycoidea: Saturniidae) and diurnal moths (Chalcosiinae: Zygaenoidea: Zygaenidae). The absorption factor of the nocturnal saturniids peaks significantly higher than the absorption factor of the diurnal chalcosiines. However, the wings of the chalcosiines absorb more ultrasound than the wings of some diurnal butterflies. Following a phylogenetic analysis on the character state of diurnality/ nocturnality in the Zygaenidae, we propose that diurnality in the Chalcosiinae is plesiomorphic (retained); hence, the absorbance of their wings is probably not a vestigial trait from an ancestral, nocturnal form but an adaptation to bat activity that overlaps their own. On a within-species level, females of the saturniids Argema mittrei and Samia cynthia ricini have significantly higher absorption factors than the males. In the female S. c. ricini, the higher absorption factor corresponds to a detection distance by bats that is at best 20-30% shorter than that of the male. © 2017. Published by The Company of Biologists Ltd.

RackSaver neutron absorbing device development and testing

International Nuclear Information System (INIS)

Lambert, R.; O'Leary, P.; Roberts, P.

1996-01-01

Siemens Power Corporation (SPC), in cooperation with the Electric Power Research Institute (EPRI), has developed the RackSaver neutron absorbing insert. The RackSaver insert can be installed onto spent nuclear fuel assemblies to replace deteriorating Boraflex neutron absorbing material installed in some spent-fuel storage racks. This paper describes results of a development and in-pool demonstration program performed to support potential utilization of the RackSaver neutron absorbing insert by affected utilities. The program objective was to advance the RackSaver concept into a field-demonstrated product. This objective was accomplished through three phases: design, licensing and criticality evaluations, and demonstration testing

Development of UV absorbing PET through Electron Irradiation

International Nuclear Information System (INIS)

Kim, Jung Woo; Lee, Na Eun; Lim, Hyung San; Park, Yang Jeong; Cho, Sung Oh

2017-01-01

Experiment to increase UV absorbance through electron beam irradiation on PET was performed. Moreover, surface hardness and roughness of each sample were observed to find the key factor increasing UV absorbance. PET sheets were irradiated with an electron beam at various fluences. The irradiated samples, as well as pristine sample, were subjected to UV-visible spectral study(UV-Vis), pencil hardness test, and scanning electron microscopy(SEM) experiment. In this study, PET samples irradiated at several conditions were analyzed through various measurements. UV absorbance-another meaning of transmittance in this study- of irradiated PET sample increased compared with pristine sample as fluence was increased in UV-Visible spectroscopy experiment.

Investigations on laser transmission welding of absorber-free thermoplastics

Science.gov (United States)

Mamuschkin, Viktor; Olowinsky, Alexander; Britten, Simon W.; Engelmann, Christoph

2014-03-01

Within the plastic industry laser transmission welding ranks among the most important joining techniques and opens up new application areas continuously. So far, a big disadvantage of the process was the fact that the joining partners need different optical properties. Since thermoplastics are transparent for the radiation of conventional beam sources (800- 1100 nm) the absorbance of one of the joining partners has to be enhanced by adding an infrared absorber (IR-absorber). Until recently, welding of absorber-free parts has not been possible. New diode lasers provide a broad variety of wavelengths which allows exploiting intrinsic absorption bands of thermoplastics. The use of a proper wavelength in combination with special optics enables laser welding of two optically identical polymer parts without absorbers which can be utilized in a large number of applications primarily in the medical and food industry, where the use of absorbers usually entails costly and time-consuming authorization processes. In this paper some aspects of the process are considered as the influence of the focal position, which is crucial when both joining partners have equal optical properties. After a theoretical consideration, an evaluation is carried out based on welding trials with polycarbonate (PC). Further aspects such as gap bridging capability and the influence of thickness of the upper joining partner are investigated as well.

14 CFR 27.475 - Tires and shock absorbers.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section 27.475 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed...

21 CFR 878.4830 - Absorbable surgical gut suture.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbable surgical gut suture. 878.4830 Section 878.4830 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... surgical gut suture. (a) Identification. An absorbable surgical gut suture, both plain and chromic, is an...

Wind-driven angular momentum loss in binary systems. I - Ballistic case

Science.gov (United States)

Brookshaw, Leigh; Tavani, Marco

1993-01-01

We study numerically the average loss of specific angular momentum from binary systems due to mass outflow from one of the two stars for a variety of initial injection geometries and wind velocities. We present results of ballistic calculations in three dimensions for initial mass ratios q of the mass-losing star to primary star in the range q between 10 exp -5 and 10. We consider injection surfaces close to the Roche lobe equipotential surface of the mass-losing star, and also cases with the mass-losing star underfilling its Roche lobe. We obtain that the orbital period is expected to have a negative time derivative for wind-driven secular evolution of binaries with q greater than about 3 and with the mass-losing star near filling its Roche lobe. We also study the effect of the presence of an absorbing surface approximating an accretion disk on the average final value of the specific angular momentum loss. We find that the effect of an accretion disk is to increase the wind-driven angular momentum loss. Our results are relevant for evolutionary models of high-mass binaries and low-mass X-ray binaries.

The Australian Commonwealth standard of measurement for absorbed radiation dose

International Nuclear Information System (INIS)

Sherlock, S.L.

1990-06-01

This report documents the absorbed dose standard for photon beams in the range from 1 to 25 MeV. Measurements of absorbed dose in graphite irradiated by a beam of cobalt-60 gamma rays from an Atomic Energy of Canada Limited (AECL) E1 Dorado 6 teletherapy unit are reported. The measurements were performed using a graphite calorimeter, which is the primary standard for absorbed dose. The measurements are used to calibrate a working standard ion chamber in terms of absorbed dose in graphite. Details of the methods, results and correction factors applied are given in Appendices. 13 refs., 6 tabs., 6 figs

Mechanochemically Driven Syntheses of Boride Nanomaterials

Science.gov (United States)

Blair, Richard G.

Solid state metathesis reactions have proven to be a viable route to the production of unfunctionalized nanomaterials. However, current implementations of this approach are limited to self-propagating reactions. We have been investigating mechanically driven metathesis reactions. The use of high-energy ball mills allows control of crystallite sizes without the use of a capping group. Reinforcement materials with crystallite sizes on the order of 5-30 nm can be produced in such a manner. Borides are of particular interest due to their strength, high melting point, and electrical conductivity. The ultimate goal of this work is to prepare oxide and capping group-free nanoparticles suitable for incorporation in thermoelectric, polymer, and ceramic composites. Ultimately this work will facilitate the production of improved thermoelectric materials that will provide robust, deployable, power generation modules to supplement or replace fuel cell, Stirling, and battery-derived power sources. It will also result in scalable, bulk syntheses of tough, refractory, conductive nanomaterials for polymer composites with improved electrical properties, ceramic composites with enhanced fracture toughness, and composites with enhanced neutron reflectance and/or absorbance.

Tribology Aspect of Rubber Shock Absorbers Development

Directory of Open Access Journals (Sweden)

M. Banić

2013-09-01

Full Text Available Rubber is a very flexible material with many desirable properties Which enable its broad use in engineering practice. Rubber or rubber-metal springs are widely used as anti-vibration or anti-shock components in technical systems. Rubber-metal springs are usually realized as a bonded assembly, however especially in shock absorbers, it is possible to realize free contacts between rubber and metal parts. In previous research it authors was observed that friction between rubber and metal in such case have a significant influence on the damping characteristics of shock absorber. This paper analyzes the development process of rubber or rubber-metal shock absorbers realized free contacts between the constitutive parts, starting from the design, construction, testing and operation, with special emphasis on the development of rubber-metal springs for the buffing and draw gear of railway vehicles.

THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z {approx}< 1

Energy Technology Data Exchange (ETDEWEB)

Lehner, N.; Howk, J. C. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Tripp, T. M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Tumlinson, J.; Thom, C.; Fox, A. J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Prochaska, J. X.; Werk, J. K. [UCO/Lick Observatory, University of California, Santa Cruz, CA (United States); O' Meara, J. M. [Department of Physics, Saint Michael' s College, Vermont, One Winooski Park, Colchester, VT 05439 (United States); Ribaudo, J. [Department of Physics, Utica College, 1600 Burrstone Road, Utica, New York 13502 (United States)

2013-06-20

We assess the metal content of the cool ({approx}10{sup 4} K) circumgalactic medium (CGM) about galaxies at z {approx}< 1 using an H I-selected sample of 28 Lyman limit systems (LLS; defined here as absorbers with 16.2 {approx}< log N{sub H{sub I}} {approx}< 18.5) observed in absorption against background QSOs by the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The N{sub H{sub I}} selection avoids metallicity biases inherent in many previous studies of the low-redshift CGM. We compare the column densities of weakly ionized metal species (e.g., O II, Si II, Mg II) to N{sub H{sub I}} in the strongest H I component of each absorber. We find that the metallicity distribution of the LLS (and hence the cool CGM) is bimodal with metal-poor and metal-rich branches peaking at [X/H] {approx_equal} -1.6 and -0.3 (or about 2.5% and 50% solar metallicities). The cool CGM probed by these LLS is predominantly ionized. The metal-rich branch of the population likely traces winds, recycled outflows, and tidally stripped gas; the metal-poor branch has properties consistent with cold accretion streams thought to be a major source of fresh gas for star forming galaxies. Both branches have a nearly equal number of absorbers. Our results thus demonstrate there is a significant mass of previously undiscovered cold metal-poor gas and confirm the presence of metal enriched gas in the CGM of z {approx}< 1 galaxies.

Study on the millimeter-wave scale absorber based on the Salisbury screen

Science.gov (United States)

Yuan, Liming; Dai, Fei; Xu, Yonggang; Zhang, Yuan

2018-03-01

In order to solve the problem on the millimeter-wave scale absorber, the Salisbury screen absorber is employed and designed based on the RL. By optimizing parameters including the sheet resistance of the surface resistive layer, the permittivity and the thickness of the grounded dielectric layer, the RL of the Salisbury screen absorber could be identical with that of the theoretical scale absorber. An example is given to verify the effectiveness of the method, where the Salisbury screen absorber is designed by the proposed method and compared with the theoretical scale absorber. Meanwhile, plate models and tri-corner reflector (TCR) models are constructed according to the designed result and their scattering properties are simulated by FEKO. Results reveal that the deviation between the designed Salisbury screen absorber and the theoretical scale absorber falls within the tolerance of radar Cross section (RCS) measurement. The work in this paper has important theoretical and practical significance in electromagnetic measurement of large scale ratio.

Comparative technical-economical analysis of solar systems with liquid absorbent

International Nuclear Information System (INIS)

Kaloyanov, N.; Popova, I.

2005-01-01

An analyses of solar water heating systems with two types liquid absorbent is presented. A system with classic collector design is used for comparison. The dependence between the value of the collectors active area and the absorbent type, collectors slope and design parameters is discussed. Two economic indexes (payback period and index of actual net value, based on the electricity price) are used for comparison of the different variants of the system. The presented results shown that: 1) the payback period can be reduced twice if the collectors with liquid absorbent are used; 2) the index of actual net value of the systems using the collectors with fluid absorbent is about four times higher than this one with classic collectors; 3) the systems using distilled water like a liquid absorbent can not fulfil the requirements for the positive economic indicators

Air-Leak Effects on Ear-Canal Acoustic Absorbance

Science.gov (United States)

Rasetshwane, Daniel M.; Kopun, Judy G.; Gorga, Michael P.; Neely, Stephen T.

2015-01-01

Objective: Accurate ear-canal acoustic measurements, such as wideband acoustic admittance, absorbance, and otoacoustic emissions, require that the measurement probe be tightly sealed in the ear canal. Air leaks can compromise the validity of the measurements, interfere with calibrations, and increase variability. There are no established procedures for determining the presence of air leaks or criteria for what size leak would affect the accuracy of ear-canal acoustic measurements. The purpose of this study was to determine ways to quantify the effects of air leaks and to develop objective criteria to detect their presence. Design: Air leaks were simulated by modifying the foam tips that are used with the measurement probe through insertion of thin plastic tubing. To analyze the effect of air leaks, acoustic measurements were taken with both modified and unmodified foam tips in brass-tube cavities and human ear canals. Measurements were initially made in cavities to determine the range of critical leaks. Subsequently, data were collected in ears of 21 adults with normal hearing and normal middle-ear function. Four acoustic metrics were used for predicting the presence of air leaks and for quantifying these leaks: (1) low-frequency admittance phase (averaged over 0.1–0.2 kHz), (2) low-frequency absorbance, (3) the ratio of compliance volume to physical volume (CV/PV), and (4) the air-leak resonance frequency. The outcome variable in this analysis was the absorbance change (Δabsorbance), which was calculated in eight frequency bands. Results: The trends were similar for both the brass cavities and the ear canals. ΔAbsorbance generally increased with air-leak size and was largest for the lower frequency bands (0.1–0.2 and 0.2–0.5 kHz). Air-leak effects were observed in frequencies up to 10 kHz, but their effects above 1 kHz were unpredictable. These high-frequency air leaks were larger in brass cavities than in ear canals. Each of the four predictor variables

Complex absorbing potentials within EOM-CC family of methods: Theory, implementation, and benchmarks

Energy Technology Data Exchange (ETDEWEB)

Zuev, Dmitry; Jagau, Thomas-C.; Krylov, Anna I. [Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482 (United States); Bravaya, Ksenia B. [Department of Chemistry, Boston University, Boston, Massachusetts 02215-2521 (United States); Epifanovsky, Evgeny [Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Q-Chem, Inc., 6601 Owens Drive, Suite 105 Pleasanton, California 94588 (United States); Shao, Yihan [Q-Chem, Inc., 6601 Owens Drive, Suite 105 Pleasanton, California 94588 (United States); Sundstrom, Eric; Head-Gordon, Martin [Department of Chemistry, University of California, Berkeley, California 94720 (United States)

2014-07-14

A production-level implementation of equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) for electron attachment and excitation energies augmented by a complex absorbing potential (CAP) is presented. The new method enables the treatment of metastable states within the EOM-CC formalism in a similar manner as bound states. The numeric performance of the method and the sensitivity of resonance positions and lifetimes to the CAP parameters and the choice of one-electron basis set are investigated. A protocol for studying molecular shape resonances based on the use of standard basis sets and a universal criterion for choosing the CAP parameters are presented. Our results for a variety of π{sup *} shape resonances of small to medium-size molecules demonstrate that CAP-augmented EOM-CCSD is competitive relative to other theoretical approaches for the treatment of resonances and is often able to reproduce experimental results.

Galactic Winds Driven by Supernovae and Radiation Pressure: Theory and Simulations

Science.gov (United States)

Zhang, Dong; Davis, Shane

2018-01-01

Galactic winds are ubiquitous in most rapidly star-forming galaxies. They are crucial to the process of galaxy formation and evolution, regulating star formation, shaping the stellar mass function and the mass-metallicity relation, and enriching the intergalactic medium with metals. Although important, the physics of galactic winds is still unclear. Winds may be driven by many mechanisms including overlapping supernovae explosions, radiation pressure of starlight on dust grains, and cosmic rays. However, the growing observations of multiphase structure in galactic winds in a large number of galaxies have not been well explained by any models. In this talk I will focus on the models of supernova- and radiation-pressure-driven winds. Using the state-of-the-art numerical simulations, I will assess the relative merits of these driving mechanisms for accelerating cold and warm clouds to observed velocities, and momentum flux boost during wind propagation.

Torsion of the central pair microtubules in eukaryotic flagella due to bending-driven lateral buckling

International Nuclear Information System (INIS)

Li, C.; Ru, C.Q.; Mioduchowski, A.

2006-01-01

Inspired by recent interest in torsion of the central pair microtubules in eukaryotic flagella, a novel thin-walled elastic beam model is suggested to study critical condition under which uniform bending of a flagellum will cause lateral/torsional buckling of the central pair. The model is directed to the central pair itself and the role of all surrounding cross-linkings inside the flagellum is modeled as an equivalent surrounding elastic medium. The model predicts that bending-driven torsion of the central pair does occur when the radius of curvature of the bent flagellum reduces to a moderate critical value typically of tens of microns. In particular, this critical value is almost independent of the flagellum length, and more sensitive to the parameters defining the surrounding elastic medium than the shear modulus of microtubules. The predicted wavelengths of the torsional buckling mode are insensitive to the flagellum length and comparable to some known related experimental data. These results indicate that torsion of the central pair microtubules in flagella is inevitable as a result of bending-driven lateral buckling. This offers an entirely new insight into the ongoing research on the mechanism of the central pair torsion

How Do Inflows and Outflows from Galaxies Create Their Inner Circumgalactic Medium?

Science.gov (United States)

Bowen, David

2017-08-01

We propose using COS to observe 7 QSO sightlines within half a virial radius each of two galaxies in order to probe their circumgalactic mediums (CGMs) along multiple sightlines. Results from higher redshift QSO absorption line surveys suggest that this is the region where most metal line absorbing gas clouds reside, but their origin remains controversial. The two spiral galaxies studied in this proposal are NGC 4565 (the Needle Galaxy) which is highly inclined (i=86 degrees), and NGC 3184, which has a very low inclination (i=9 degrees). Their orientation makes them ideal targets for looking for kinematic and metallicity signatures from outflows along the minor axis, or inflows into the disk along the major axis. For both galaxies, we will measure how HI and metal line column densities change globally with radius, and how the ionzation structure of the absorbers varies with position. We predict that the HI column densities we detect will be similar to the Lyman Limit, or partial-Lyman Limit systems, and that we will be able to measure the gas metallicity in these clouds. These measurements can be used to infer whether the absorbing gas is flowing into the galaxy from the IGM (where the metallicity is lower than in the galaxy) or out of the galaxy (which should be metal enriched). Given that LLS and pLLS have been shown to have a bimodal distribution in their metallicity, we will see which of the two regimes the gas in our galaxies belong to, and even whether the bimodality can be seen in a single galaxy towards different sightlines.

Spacesuit Evaporator-Absorber-Radiator (SEAR)

Data.gov (United States)

National Aeronautics and Space Administration — The primary goal is to build and test a rigid Lithium Chloride Absorber Radiator (LCAR) coupon based on honeycomb geometry that would be applicable for EVA and...

Nanoparticles generated by laser in liquids as contrast medium and radiotherapy intensifiers

Science.gov (United States)

Restuccia, Nancy; Torrisi, Lorenzo

2018-01-01

The synthesis of Au and Ag nanoparticles (NP) though laser ablation in liquids as a function the laser parameters is presented. Spherical NPs with diameter distribution within 1 and 100 nm were prepared by laser ablation in water. The nanoparticles characterization was performed using optical spectroscopy and electronic microscopy (SEM and TEM) measurements. Studies of the possible use of metallic nanoparticles as intensifier of diagnostics imaging contrast medium and absorbing dose from ionizing radiations in traditional radiotherapy and protontherapy are presented. Examples of in vitro (in tissue equivalent materials) and in vivo (in mice), were conducted thank to simulation programs permitting to evaluate the enhancement of efficiency in imaging and therapy as a function of the NPs concentrations and irradiation conditions.

Nanoparticles generated by laser in liquids as contrast medium and radiotherapy intensifiers

Directory of Open Access Journals (Sweden)

Restuccia Nancy

2018-01-01

Full Text Available The synthesis of Au and Ag nanoparticles (NP though laser ablation in liquids as a function the laser parameters is presented. Spherical NPs with diameter distribution within 1 and 100 nm were prepared by laser ablation in water. The nanoparticles characterization was performed using optical spectroscopy and electronic microscopy (SEM and TEM measurements. Studies of the possible use of metallic nanoparticles as intensifier of diagnostics imaging contrast medium and absorbing dose from ionizing radiations in traditional radiotherapy and protontherapy are presented. Examples of in vitro (in tissue equivalent materials and in vivo (in mice, were conducted thank to simulation programs permitting to evaluate the enhancement of efficiency in imaging and therapy as a function of the NPs concentrations and irradiation conditions.

Diffuse X-ray Background Constraints on Models of the Local Interstellar Medium

International Nuclear Information System (INIS)

Snowden, S L

2015-01-01

There is a flux of soft X-rays (0.07–0.284 keV) of diffuse origin observable over the entire sky. As X-rays of this energy are strongly absorbed by the interstellar medium (ISM), one optical depth is 10 19 – 10 20 H cm −2 , they provide a unique probe of neutral material in the solar vicinity. However, to be an effective probe requires that the distribution of emission be well understood, a requirement that is currently unfulfilled (although progress is being made), with unclear fractions originating in the Galactic halo, Local Hot Bubble, heliosphere, and Earth's magnetosheath. The various available data, their consistency (or lack thereof), and their implications for understanding the very local ISM are briefly discussed

A high absorbance material for solar collectors' applications

International Nuclear Information System (INIS)

Oliva, A I; Maldonado, R D; Díaz, E A; Montalvo, A I

2013-01-01

In this work, we proposed a low cost material to be used as an excellent absorber for solar collectors, to increase its thermal efficiency by the high capacity to absorb solar radiation. The material, known as 'smoke black' (soot) can be obtained by the incomplete combustion of organic materials, such as the oxygen-acetylene, paraffin, or candles. A comparative analysis between the optical properties (reflectance, absorbance, and emissivity) measured on three covered copper surfaces (without paint, with a commercial matte black paint, and with smoke black) shows amazing optical results for the smoke black. Reflectance values of the smoke black applied over copper surfaces improves 56 times the values obtained from commercial black paints. High values of emissivity (E=0.9988) were measured on the surface covered with smoke black by spectrophotometry in the UV-VIS range, which represents about 7% of increment as compared with the value obtained for commercial black paints (E=0.938). The proposed high absorbance material can be easily applied on any kind of surfaces at low cost.

Absorbers in the Transactional Interpretation of Quantum Mechanics

Science.gov (United States)

Boisvert, Jean-Sébastien; Marchildon, Louis

2013-03-01

The transactional interpretation of quantum mechanics, following the time-symmetric formulation of electrodynamics, uses retarded and advanced solutions of the Schrödinger equation and its complex conjugate to understand quantum phenomena by means of transactions. A transaction occurs between an emitter and a specific absorber when the emitter has received advanced waves from all possible absorbers. Advanced causation always raises the specter of paradoxes, and it must be addressed carefully. In particular, different devices involving contingent absorbers or various types of interaction-free measurements have been proposed as threatening the original version of the transactional interpretation. These proposals will be analyzed by examining in each case the configuration of absorbers and, in the special case of the so-called quantum liar experiment, by carefully following the development of retarded and advanced waves through the Mach-Zehnder interferometer. We will show that there is no need to resort to the hierarchy of transactions that some have proposed, and will argue that the transactional interpretation is consistent with the block-universe picture of time.

Photothermally Driven Refreshable Microactuators Based on Graphene Oxide Doped Paraffin.

Science.gov (United States)

Hou, Sichao; Wang, Miao; Guo, Shouwu; Su, Ming

2017-08-09

Actuators based on phase change materials (paraffin) can simultaneously produce large stroke length and large force due to thermal expansion, but the low thermal conductivity of paraffin requires high power input and long actuation time. The graphene oxide (GO) doped paraffin dynamic actuator addresses the key challenges in the design of thermal phase change actuators: Thermal conductivity and light absorbing are increased, and the response time is reduced compared to the standard phase change actuator designed with metal heating resistors. The thermal properties of GO-paraffin composites with varied loading amount are characterized to confirm the optimal loading amount of 1.0%. A multicell phase change actuator was integrated into a digital micromirror controlled optical system. A series of photothermally driven refreshable patterns were generated and confirmed with infrared imaging.

Efficacy and Safety of the Absorb Everolimus-Eluting Bioresorbable Scaffold for Treatment of Patients With Diabetes Mellitus: Results of the Absorb Diabetic Substudy.

Science.gov (United States)

Kereiakes, Dean J; Ellis, Stephen G; Kimura, Takeshi; Abizaid, Alexandre; Zhao, Weiying; Veldhof, Susan; Vu, Minh-Thien; Zhang, Zhen; Onuma, Yoshinobu; Chevalier, Bernard; Serruys, Patrick W; Stone, Gregg W

2017-01-09

The study sought to evaluate the efficacy and safety of the Absorb everolimus-eluting bioresorbable vascular scaffold (BVS) (Abbott Vascular, Abbott Park, Illinois) in patients with diabetes mellitus. Randomized, controlled trials have demonstrated comparable clinical outcomes following percutaneous coronary intervention with either Absorb BVS or metallic Xience everolimus-eluting stent. However, these trials lack power required to provide reliable treatment effect estimates in this high-risk population. In a pre-specified, powered analysis, patients with diabetes who received ≥1 Absorb were pooled from the ABSORB II, III, and JAPAN randomized trials and from the single arm ABSORB EXTEND registry. The study composite primary endpoint was target lesion failure (TLF) at 1 year following Absorb BVS compared with a performance goal of 12.7%. Among 754 diabetic patients included in analysis (27.3% insulin treated), the 1-year TLF rate was 8.3% (upper 1-sided 95% confidence limit: 10.1%; p = 0.0001 vs. performance goal). Scaffold thrombosis (definite or probable) was observed in 2.3% of patients. Multivariable regression identified older age, insulin treatment, and smaller pre-procedure reference vessel diameter as significant independent predictors of 1-year TLF. The Absorb diabetic substudy suggests efficacy and safety of the Absorb BVS for treatment of patients with diabetes mellitus. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Characteristics of NaNO3-Promoted CdO as a Midtemperature CO2 Absorbent.

Science.gov (United States)

Kim, Kang-Yeong; Kwak, Jin-Su; An, Young-In; Oh, Kyung-Ryul; Kwon, Young-Uk

2017-06-28

In this study, we explored the reaction system CdO(s) + CO 2 (g) ⇄ CdCO 3 (s) as a model system for CO 2 capture agent in the intermediate temperature range of 300-400 °C. While pure CdO does not react with CO 2 at all up to 500 °C, CdO mixed with an appropriate amount of NaNO 3 (optimal molar ratio NaNO 3 /CdO = 0.14) greatly enhances the conversion of CdO into CdCO 3 up to ∼80% (5.68 mmol/g). These NaNO 3 -promoted CdO absorbents can undergo many cycles of absorption and desorption by temperature swing between 300 and 370 °C under a 100% CO 2 condition. Details of how NaNO 3 promotes the CO 2 absorption of CdO have been delineated through various techniques using thermogravimetry, coupled with X-ray diffraction and electron microscopy. On the basis of the observed data, we propose a mechanism of CO 2 absorption and desorption of NaNO 3 -promoted CdO. The absorption proceeds through a sequence of events of CO 2 adsorption on the CdO surface covered by NaNO 3 , dissolution of so-formed CdCO 3 , and precipitation of CdCO 3 particles in the NaNO 3 medium. The desorption occurs through the decomposition of CdCO 3 in the dissolved state in the NaNO 3 medium where CdO nanoparticles are formed dispersed in the NaNO 3 medium. The CdO nanoparticles are aggregated into micrometer-large particles with smooth surfaces and regular shapes.

A concentrated solar cavity absorber with direct heat transfer through recirculating metallic particles

Energy Technology Data Exchange (ETDEWEB)

Sarker, M. R. I., E-mail: islamrabiul@yahoo.com; Saha, Manabendra, E-mail: manabendra.saha@adelaide.edu.au, E-mail: manab04me@gmail.com; Beg, R. A. [Department of Mechanical Engineering, Rajshahi University of Engineering and Technology, Rajshahi-6204 (Bangladesh)

2016-07-12

A recirculating flow solar particle cavity absorber (receiver) is modeled to investigate the flow behavior and heat transfer characteristics of a novel developing concept. It features a continuous recirculating flow of non-reacting metallic particles (black silicon carbide) with air which are used as a thermal enhancement medium. The aim of the present study is to numerically investigate the thermal behavior and flow characteristics of the proposed concept. The proposed solar particle receiver is modeled using two phase discrete particle model (DPM), RNG k-flow model and discrete ordinate (DO) radiation model. Numerical analysis is carried out considering a solar receiver with only air and the mixture of non-reacting particles and air as a heat transfer as well as heat carrying medium. The parametric investigation is conducted considering the incident solar flux on the receiver aperture and changing air flow rate and recirculation rate inside the receiver. A stand-alone feature of the recirculating flow solar particle receiver concept is that the particles are directly exposed to concentrated solar radiation monotonously through recirculating flow inside the receiver and results in efficient irradiation absorption and convective heat transfer to air that help to achieve high temperature air and consequently increase in thermal efficiency. This paper presents, results from the developed concept and highlights its flow behavior and potential to enhance the heat transfer from metallic particles to air by maximizing heat carrying capacity of the heat transfer medium. The imposed milestones for the present system will be helpful to understand the radiation absorption mechanism of the particles in a recirculating flow based receiver, the thermal transport between the particles, the air and the cavity, and the fluid dynamics of the air and particle in the cavity.

Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets.

Science.gov (United States)

Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

2015-09-10

Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

Phase Space Exchange in Thick Wedge Absorbers

Energy Technology Data Exchange (ETDEWEB)

Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2017-01-01

The problem of phase space exchange in wedge absorbers with ionization cooling is discussed. The wedge absorber exchanges transverse and longitudinal phase space by introducing a position-dependent energy loss. In this paper we note that the wedges used with ionization cooling are relatively thick, so that single wedges cause relatively large changes in beam phase space. Calculation methods adapted to such “thick wedge” cases are presented, and beam phase-space transformations through such wedges are discussed.

Insight into magnetorheological shock absorbers

CERN Document Server

Gołdasz, Janusz

2015-01-01

This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston.

Quantum walk with one variable absorbing boundary

International Nuclear Information System (INIS)

Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli

2017-01-01

Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks. - Highlights: • A novel scheme about quantum walk with variable boundary is proposed. • The analytical results of the survival probability from the absorbing boundary. • The behavior of survival probability under different boundary conditions. • The influence of different initial coin states on the survival probability.

Absorber rod driving into a gas-cooled nuclear reactor

International Nuclear Information System (INIS)

Elter, C.; Schmitt, H.; Schoening, J.

1987-01-01

The absorber rod consists of a hollow cylinder which has a layer of absorber material applied on its inside circumferential surface. The absorber rod is held via a guide sleeve, which is supported centrally in a hole in the side reflector. The guidance within the sleeve is provided by flanges on the hollow cylinder. The movement of the hollow cylinder is carried out hydraulically or pneumatically. A flow of cooling gas is used for cooling, which is passed through the inner central areas of the hollow cylinder and the guide sleeve. (DG) [de

Broadband near-infrared metamaterial absorbers utilizing highly lossy metals

DEFF Research Database (Denmark)

Ding, Fei; Dai, Jin; Chen, Yiting

2016-01-01

Radiation absorbers have increasingly been attracting attention as crucial components for controllable thermal emission, energy harvesting, modulators, etc. However, it is still challenging to realize thin absorbers which can operate over a wide spectrum range. Here, we propose and experimentally...... demonstrate thin, broadband, polarization-insensitive and omnidirectional absorbers working in the near-infrared range. We choose titanium (Ti) instead of the commonly used gold (Au) to construct nano-disk arrays on the top of a silicon dioxide (SiO2) coated Au substrate, with the quality (Q) factor...

Convection-type LH2 absorber R and D for muon ionization cooling

International Nuclear Information System (INIS)

Ishimoto, S.; Bandura, L.; Black, E.L.; Boghosian, M.; Cassel, K.W.; Cummings, M.A.; Darve, C.; Dyshkant, A.; Errede, D.; Geer, S.; Haney, M.; Hedin, D.; Johnson, R.; Johnstone, C.J.; Kaplan, D.M.; Kubik, D.; Kuno, Y.; Majewski, S.; Popovic, M.; Reep, M.; Summers, D.; Suzuki, S.; Yoshimura, K.

2003-01-01

A feasibility study on liquid hydrogen (LH 2 ) absorbers for muon ionization cooling is reported. In muon ionization cooling, an LH 2 absorber is required to have a high cooling power greater than 100 W to cool heat deposited by muons passing through. That heat in LH 2 can be removed at either external or internal heat exchangers, which are cooled by cold helium gas. As one of the internal heat exchanger types, a convection-type absorber is proposed. In the convection-type absorber, heat is taken away by the convection of LH 2 in the absorber. The heat exchanger efficiency for the convection-type absorber is calculated. A possible design is presented

Design and analysis of lumped resistor loaded metamaterial absorber with transmission band.

Science.gov (United States)

Chen, Xi; Li, Youquan; Fu, Yunqi; Yuan, Naichang

2012-12-17

A new type of multi-layer metamaterial (MM) absorber is represented in this paper, which behave as a dielectric slab in transmission band and act as an absorber in another lower band. The equivalent circuit model of each layer in this MM absorber has been established. The transmission line (TL) model is introduced to analysis the mechanism of electromagnetic wave traveling through this MM absorber. Both theoretical and experimental results indicate this MM absorber has a transmission band at 21GHz and an absorptive band from 5GHz to 13GHz. A good match of TL model results and measurement results verified the validity of TL model in analyzing and optimizing the performances of this kind of absorber.

Mathematical solutions of rate equations of a laser-diode end-pumped passively Q-switched and mode locked Nd-laser with Cr4+:YAG polarized saturable absorber

International Nuclear Information System (INIS)

Abdul Ghani, B.; Hammadi, M.

2012-01-01

The intracavity frequency-doubling (IFD) of a simultaneous passively Q-switched mode-locked diode-pumped Nd 3 + - laser is studied with a polarized isotropic Cr 4 +: YAG saturable absorber. A general recurrence formula for the mode-locked pulses under the Q-switched envelope at fundamental wavelength has been reconstructed in order to analyze the temporal shape behavior of a single Q-switched envelope with mode-locking pulse trains. This formula has been derived taking into account the impact of the IFD and polarized Cr 4 +: YAG saturable absorber.The presented mathematical model describes the self-induced anisotropy appeared in the polarized Cr 4 +: YAG in the nonlinear stage of the giant pulse formation. For the anisotropic Nd 3 +: YVO 4 active medium, the generated polarized waves are assumed to be fixed through the lasing cycle. Besides, the maximum absorber initial transmission and the minimum mirror reflectivity values have been determined from the second threshold criterion. The calculated numerical results demonstrate the impact of the variation of the input laser parameters (rotational angle of the polarized crystal, absorber initial transmission and the output mirror reflectivity) on the characteristics of the output laser pulse (SH peak power, pulse width, pulse duration and shift pulse position of central mode). The calculated numerical results in this work is in good qualitative and quantitative agreement with the available experimental data reported in the references. (author)

Self-assembly of highly efficient, broadband plasmonic absorbers for solar steam generation.

Science.gov (United States)

Zhou, Lin; Tan, Yingling; Ji, Dengxin; Zhu, Bin; Zhang, Pei; Xu, Jun; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

2016-04-01

The study of ideal absorbers, which can efficiently absorb light over a broad range of wavelengths, is of fundamental importance, as well as critical for many applications from solar steam generation and thermophotovoltaics to light/thermal detectors. As a result of recent advances in plasmonics, plasmonic absorbers have attracted a lot of attention. However, the performance and scalability of these absorbers, predominantly fabricated by the top-down approach, need to be further improved to enable widespread applications. We report a plasmonic absorber which can enable an average measured absorbance of ~99% across the wavelengths from 400 nm to 10 μm, the most efficient and broadband plasmonic absorber reported to date. The absorber is fabricated through self-assembly of metallic nanoparticles onto a nanoporous template by a one-step deposition process. Because of its efficient light absorption, strong field enhancement, and porous structures, which together enable not only efficient solar absorption but also significant local heating and continuous stream flow, plasmonic absorber-based solar steam generation has over 90% efficiency under solar irradiation of only 4-sun intensity (4 kW m(-2)). The pronounced light absorption effect coupled with the high-throughput self-assembly process could lead toward large-scale manufacturing of other nanophotonic structures and devices.

Investigation of the Klinkenberg effect in a micro/nanoporous medium by direct simulation Monte Carlo method

Science.gov (United States)

Yang, Guang; Weigand, Bernhard

2018-04-01

The pressure-driven gas transport characteristics through a porous medium consisting of arrays of discrete elements is investigated by using the direct simulation Monte Carlo (DSMC) method. Different porous structures are considered, accounting for both two- and three-dimensional arrangements of basic microscale and nanoscale elements. The pore scale flow patterns in the porous medium are obtained, and the Knudsen diffusion in the pores is studied in detail for slip and transition flow regimes. A new effective pore size of the porous medium is defined, which is a function of the porosity, the tortuosity, the contraction factor, and the intrinsic permeability of the porous medium. It is found that the Klinkenberg effect in different porous structures can be fully described by the Knudsen number characterized by the effective pore size. The accuracies of some widely used Klinkenberg correlations are evaluated by the present DSMC results. It is also found that the available correlations for apparent permeability, most of which are derived from simple pipe or channel flows, can still be applicative for more complex porous media flows, by using the effective pore size defined in this study.

A biomimetic absorbent for removal of trace level persistent organic pollutants from water

International Nuclear Information System (INIS)

Liu Huijuan; Qu Jiuhui; Dai Ruihua; Ru Jia; Wang Zijian

2007-01-01

A novel biomimetic absorbent containing the lipid triolein was developed for removing persistent organic pollutants (POPs) from water. The structural characteristics of the absorbent were obtained by SEM and a photoluminescence method. Under optimum preparation conditions, triolein was perfectly embedded in the cellulose acetate (CA) spheres, the absorbent was stable and no triolein leaked into the water. Dieldrin, endrin, aldrin and heptachlor epoxide were effectively removed by the CA-triolein absorbent in laboratory batch experiments. This suggests that CA-triolein absorbent may serve as a good absorbent for those selected POPs. Triolein in the absorbent significantly increased the absorption capacity, and lower residual concentrations of POPs were achieved when compared to the use of cellulose acetate absorbent. The absorption rate for lipophilic pollutants was very fast and exhibited some relationship with the octanol-water partition coefficient of the analyte. The absorption mechanism is discussed in detail. - Triolein-embedded absorbent was developed and it could remove lipophilic pollutants from water effectively

Medium-Based Design: Extending a Medium to Create an Exploratory Learning Environment

Science.gov (United States)

Rick, Jochen; Lamberty, K. K.

2005-01-01

This article introduces "medium-based" design -- an approach to creating "exploratory learning environments" using the method of "extending a medium". First, the characteristics of exploratory learning environments and medium-based design are described and grounded in related work. Particular attention is given to "extending a medium" --…

Thermal expansion absorbing structure for pipeline

International Nuclear Information System (INIS)

Nagata, Takashi; Yamashita, Takuya.

1995-01-01

A thermal expansion absorbing structure for a pipeline is disposed to the end of pipelines to form a U-shaped cross section connecting a semi-circular torus shell and a short double-walled cylindrical tube. The U-shaped longitudinal cross-section is deformed in accordance with the shrinking deformation of the pipeline and absorbs thermal expansion. Namely, since the central lines of the outer and inner tubes of the double-walled cylindrical tube deform so as to incline, when the pipeline is deformed by thermal expansion, thermal expansion can be absorbed by a simple configuration thereby enabling to contribute to ensure the safety. Then, the entire length of the pipeline can greatly be shortened by applying it to the pipeline disposed in a high temperature state compared with a method of laying around a pipeline using only elbows, which has been conducted so far. Especially, when it is applied to a pipeline for an FBR-type reactor, the cost for the construction of a facility of a primary systems can greater be reduced. In addition, it can be applied to a pipeline for usual chemical plants and any other structures requiring absorption of deformation. (N.H.)

Effects of medium-chain fatty acids and oleic acid on blood lipids, lipoproteins, glucose, insulin, and lipid transfer protein activities

DEFF Research Database (Denmark)

Tholstrup, T.; Ehnholm, C.; Jauhiainen, M.

2004-01-01

Background: Dietary medium-chain fatty acids (MCFAs) are of nutritional interest because they are more easily absorbed from dietary medium-chain triacylglycerols (MCTs) than are long-chain fatty acids from, for example, vegetable oils. It has generally been claimed that MCFAs do not increase plasma...... cholesterol, although this claim is poorly documented. Objective: We compared the effects of a diet rich in either MCFAs or oleic acid on fasting blood lipids, lipoproteins, glucose, insulin, and lipid transfer protein activities in healthy men. Design: In a study with a double-blind, randomized, crossover...... plasma total triacylglycerol (P = 0.0361), and higher plasma glucose (P = 0.033). Plasma HDL-cholesterol and insulin concentrations and activities of cholesterol ester transfer protein and phospholipid transfer protein did not differ significantly between the diets. Conclusions: Compared with fat high...

Fast neutron radiation inactivation of Bacillus subtilis: Absorbed dose determination

International Nuclear Information System (INIS)

Song Lingli; Zheng Chun; Ai Zihui; Li Junjie; Dai Shaofeng

2011-01-01

In this paper, fast neutron inactivation effects of Bacillus subtilis were investigated with fission fast neutrons from CFBR-II reactor of INPC (Institute of Nuclear Physics and Chemistry) and mono-energetic neutrons from the Van de Graaff accelerator at Peking University. The method for determining the absorbed dose in the Bacillus subtilis suspension contained in test tubes is introduced. The absorbed dose, on account of its dependence on the volume and the form of confined state, was determined by combined experiments and Monte Carlo method. Using the calculation results of absorbed dose, the fast neutron inactivation effects on Bacillus subtilis were studied. The survival rates and absorbed dose curve was constructed. (authors)

Low fluid level in pulse rod shock absorber

Energy Technology Data Exchange (ETDEWEB)

Aderhold, H. C.

1974-07-01

On various occasions during pulse mode operation the shim and regulating control rods would drop when the pulse rod was withdrawn. Subsequent investigation traced the problem to the pulse rod shock absorber which was found to be low in hydraulic fluid. The results of the investigation, the corrective action taken, and a method for measuring the shock absorber fluid level are presented. (author)

Low fluid level in pulse rod shock absorber

International Nuclear Information System (INIS)

Aderhold, H.C.

1974-01-01

On various occasions during pulse mode operation the shim and regulating control rods would drop when the pulse rod was withdrawn. Subsequent investigation traced the problem to the pulse rod shock absorber which was found to be low in hydraulic fluid. The results of the investigation, the corrective action taken, and a method for measuring the shock absorber fluid level are presented. (author)

Reflection and Refraction of Light in Absorbing Media

Science.gov (United States)

Katsumata, Koichi; Sasaki, Shosuke

2018-05-01

The results of a rigorous calculation of optical phenomena in absorbing media based on Maxwell's equations are reported. In the case of an absorbing dielectric, we assume a complex dielectric constant. We find an expression for the angle of refraction as a function of the incident angle and the real and imaginary parts of the complex dielectric constant, all of which are real. The amplitudes of the reflected and transmitted waves are calculated on the same footing. These amplitudes are shown to be complex, from which we deduce the magnitude and phase change of the reflection and transmission coefficients. The same argument applies to an absorbing magnetic material if we replace the complex dielectric constant by a complex magnetic permeability.

Analysis of buffering process of control rod hydraulic absorber

International Nuclear Information System (INIS)

Bao Jishi; Qin Benke; Bo Hanliang

2011-01-01

Control Rod Hydraulic Drive Mechanism(CRHDM) is a newly invented build-in control rod drive mechanism. Hydraulic absorber is the key part of this mechanism, and is used to cushion the control rod when the rod scrams. Thus, it prevents the control rod from being deformed and damaged. In this paper dynamics program ANSYS CFX is used to calculate all kinds of flow conditions in hydraulic absorber to obtain its hydraulic characteristics. Based on the flow resistance coefficients obtained from the simulation results, fluid mass and momentum equations were developed to get the trend of pressure change in the hydraulic cylinder and the displacement of the piston rod during the buffering process of the control rod. The results obtained in this paper indicate that the hydraulic absorber meets the design requirement. The work in this paper will be helpful for the design and optimization of the control rod hydraulic absorber. (author)

Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS

Directory of Open Access Journals (Sweden)

Kyeongseob Kim

2016-04-01

Full Text Available A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS. To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm to 6.4 cm.

Recent developments of smart electromagnetic absorbers based polymer-composites at gigahertz frequencies

International Nuclear Information System (INIS)

Idris, Fadzidah Mohd.; Hashim, Mansor; Abbas, Zulkifly; Ismail, Ismayadi; Nazlan, Rodziah; Ibrahim, Idza Riati

2016-01-01

The rapid increase in electromagnetic interference has received a serious attention from researchers who responded by producing a variety of radar absorbing materials especially at high gigahertz frequencies. Ongoing investigation is being carried out in order to find the best absorbing materials which can fulfill the requirements for smart absorbing materials which are lightweight, broad bandwidth absorption, stronger absorption etc. Thus, to improve the absorbing capability, several important parameters need to be taken into consideration such as filler type, loading level, type of polymer matrix, physical thickness, grain sizes, layers and bandwidth. Therefore, this article introduces the electromagnetic wave absorption mechanisms and then reveals and reviews those parameters that enhance the absorption performance. - Highlights: • Development variety of radar absorbing materials especially at high gigahertz frequencies. • Best absorbing materials which can fulfill the requirements for smart absorbing materials which are lightweight, broad bandwidth absorption, stronger absorption etc. • Important parameters need to be taken into consideration to obtain stronger absorption and better performances.

Neutron absorbing article and method for manufacture of such article

International Nuclear Information System (INIS)

Hortman, M.T.; Mcmurtry, C.H.; Naum, R.G.; Owens, D.P.

1980-01-01

A neutron absorbing article, preferably in long, thin, flat form , suitable for but not necessarily limited to use in storage racks for spent nuclear fuel at locations between volumes of such stored fuel, to absorb neutrons from said spent fuel and prevent uncontrolled nuclear reaction of the spent fuel material, is composed of finely divided boron carbide particles and a solid, irreversibly cured phenolic polymer, forming a continuous matrix about the boron carbide particles, in such proportions that at least 6% of b10 from the boron carbide content is present therein. The described articles withstand thermal cycling from repeated spent fuel insertions and removals, withstand radiation from said spent nuclear fuel over long periods of time without losing desirable neutron absorbing and physical properties, are sufficiently chemically inert to water so as to retain neutron absorbing properties if brought into contact with it, are not galvanically corrodible and are sufficiently flexible so as to withstand operational basis earthquake and safe shutdown earthquake seismic events, without loss of neutron absorbing capability and other desirable properties, when installed in storage racks for spent nuclear fuel. The disclosure also relates to a plurality of such neutron absorbing articles in a storage rack for spent nuclear fuel and to a method for the manufacture of the articles

Neutron absorbed dose in a pacemaker CMOS

International Nuclear Information System (INIS)

Borja H, C. G.; Guzman G, K. A.; Valero L, C.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R.; Paredes G, L.

2012-01-01

The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor (CMOS), has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1.522 x 10 -17 Gy per neutron emitted by the source. (Author)

Neutron absorbed dose in a pacemaker CMOS

Energy Technology Data Exchange (ETDEWEB)

Borja H, C. G.; Guzman G, K. A.; Valero L, C.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: fermineutron@yahoo.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2012-06-15

The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor (CMOS), has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1.522 x 10{sup -17} Gy per neutron emitted by the source. (Author)

Aluminum alloy excellent in neutron absorbing performance

International Nuclear Information System (INIS)

Iida, Tetsuya; Tamamura, Tadao; Morimoto, Hiroyuki; Ouchi, Ken-ichiro.

1987-01-01

Purpose: To obtain structural materials made of aluminum alloys having favorable neutron absorbing performance and excellent in the performance as structural materials such as processability and strength. Constitution: Powder of Gd 2 O 3 as a gadolinium compound or metal gadolinium is uniformly mixed with the powder of aluminum or aluminum alloy. The amount of the gadolinium compound added is set to 0.1 - 30 % by weight. No sufficient neutron absorbing performance can be obtained if it is less than 0.1 % by weight, whereas the processability and mechanical property of the alloy are degraded if it exceeds 30 % by weight. Further, the grain size is set to less about 50 μm. Further, since the neutron absorbing performance varies greatly if the aluminum powder size exceeds 100 μm, the diameter is set to less than about 100 μm. These mixtures are molded in a hot press. This enables to obtain aimed structural materials. (Takahashi, M.)

Integration of regenerative shock absorber into vehicle electric system

Science.gov (United States)

Zhang, Chongxiao; Li, Peng; Xing, Shaoxu; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

2014-03-01

Regenerative/Energy harvesting shock absorbers have a great potential to increase fuel efficiency and provide suspension damping simultaneously. In recent years there's intensive work on this topic, but most researches focus on electricity extraction from vibration and harvesting efficiency improvement. The integration of electricity generated from regenerative shock absorbers into vehicle electric system, which is very important to realize the fuel efficiency benefit, has not been investigated. This paper is to study and demonstrate the integration of regenerative shock absorber with vehicle alternator, battery and in-vehicle electrical load together. In the presented system, the shock absorber is excited by a shaker and it converts kinetic energy into electricity. The harvested electricity flows into a DC/DC converter which realizes two functions: controlling the shock absorber's damping and regulating the output voltage. The damping is tuned by controlling shock absorber's output current, which is also the input current of DC/DC converter. By adjusting the duty cycles of switches in the converter, its input impedance together with input current can be adjusted according to dynamic damping requirements. An automotive lead-acid battery is charged by the DC/DC converter's output. To simulate the working condition of combustion engine, an AC motor is used to drive a truck alternator, which also charges the battery. Power resistors are used as battery's electrical load to simulate in-vehicle electrical devices. Experimental results show that the proposed integration strategy can effectively utilize the harvested electricity and power consumption of the AC motor is decreased accordingly. This proves the combustion engine's load reduction and fuel efficiency improvement.

Analysis of solar water heater with parabolic dish concentrator and conical absorber

Science.gov (United States)

Rajamohan, G.; Kumar, P.; Anwar, M.; Mohanraj, T.

2017-06-01

This research focuses on developing novel technique for a solar water heating system. The novel solar system comprises a parabolic dish concentrator, conical absorber and water heater. In this system, the conical absorber tube directly absorbs solar radiation from the sun and the parabolic dish concentrator reflects the solar radiations towards the conical absorber tube from all directions, therefore both radiations would significantly improve the thermal collector efficiency. The working fluid water is stored at the bottom of the absorber tubes. The absorber tubes get heated and increases the temperature of the working fluid inside of the absorber tube and causes the working fluid to partially evaporate. The partially vaporized working fluid moves in the upward direction due to buoyancy effect and enters the heat exchanger. When fresh water passes through the heat exchanger, temperature of the vapour decreases through heat exchange. This leads to condensation of the vapour and forms liquid phase. The working fluid returns to the bottom of the collector absorber tube by gravity. Hence, this will continue as a cyclic process inside the system. The proposed investigation shows an improvement of collector efficiency, enhanced heat transfer and a quality water heating system.

Digital Alloy Absorber for Photodetectors

Science.gov (United States)

Hill, Cory J. (Inventor); Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor)

2016-01-01

In order to increase the spectral response range and improve the mobility of the photo-generated carriers (e.g. in an nBn photodetector), a digital alloy absorber may be employed by embedding one (or fraction thereof) to several monolayers of a semiconductor material (insert layers) periodically into a different host semiconductor material of the absorber layer. The semiconductor material of the insert layer and the host semiconductor materials may have lattice constants that are substantially mismatched. For example, this may performed by periodically embedding monolayers of InSb into an InAsSb host as the absorption region to extend the cutoff wavelength of InAsSb photodetectors, such as InAsSb based nBn devices. The described technique allows for simultaneous control of alloy composition and net strain, which are both key parameters for the photodetector operation.

Design of absorber assemblies with intentional pellet-cladding mechanical interaction

International Nuclear Information System (INIS)

Hollenberg, G.W.; Birney, K.R.; Pitner, A.L.; Basmajian, J.A.

1980-04-01

A number of improvements in absorber assembly performance characteristics can be achieved through implementation of absorber cladding mechanical interaction (ACMI). Benefits include lower operating temperatures, less potential for material relocation, longer lifetime, and increased reactivity worth. Analyses indicate that substantial cladding strains may be attainable without significant risk of breach. However, actual in-reactor testing of ACMI in absorber elements will be required before design criteria can be revised to accept ACMI

Transmission line model and fields analysis of metamaterial absorber in the terahertz band.

Science.gov (United States)

Wen, Qi-Ye; Xie, Yun-Song; Zhang, Huai-Wu; Yang, Qing-Hui; Li, Yuan-Xun; Liu, Ying-Li

2009-10-26

Metamaterial (MM) absorber is a novel device to provide near-unity absorption to electromagnetic wave, which is especially important in the terahertz (THz) band. However, the principal physics of MM absorber is still far from being understood. In this work, a transmission line (TL) model for MM absorber was proposed, and with this model the S-parameters, energy consumption, and the power loss density of the absorber were calculated. By this TL model, the asymmetric phenomenon of THz absorption in MM absorber is unambiguously demonstrated, and it clarifies that strong absorption of this absorber under studied is mainly related to the LC resonance of the split-ring-resonator structure. The distribution of power loss density in the absorber indicates that the electromagnetic wave is firstly concentrated into some specific locations of the absorber and then be strongly consumed. This feature as electromagnetic wave trapper renders MM absorber a potential energy converter. Based on TL model, some design strategies to widen the absorption band were also proposed for the purposes to extend its application areas.

Energy Analysis of Solar Collector With perforated Absorber Plate

Directory of Open Access Journals (Sweden)

Ammar A. Farhan

2017-09-01

Full Text Available The thermal performance of three solar collectors with 3, 6 mm and without perforation absorber plate was assessed experimentally. The experimental tests were implemented in Baghdad during the January and February 2017. Five values of airflow rates range between 0.01 – 0.1 m3/s were used through the test with a constant airflow rate during the test day. The variation of the following parameters air temperature difference, useful energy, absorber plate temperature, and collector efficiency was recorded every 15 minutes. The experimental data reports that the increases the number of absorber plate perforations with a small diameter is more efficient rather than increasing the hole diameter of the absorber plate with decreasing the perforation numbers. Maximum air temperature difference throughout the solar collector with 3, 6 mm perforations and without perforations are 17, 15, and 12 oC, respectively. Also, it can be concluded that the energy gained from the solar collector with 3 mm perforation absorber plate is 28.2 % more than the energy gained from solar collector without holes per day for 0.1 m3/s airflow rate. The maximum values of the thermal performance curves are 0.67, 0.64, and 0.56 for the solar collector with 3, 6 mm, and without perforations, respectively.

Parameter optimization method for longitudinal vibration absorber of ship shaft system

Directory of Open Access Journals (Sweden)

LIU Jinlin

2017-05-01

Full Text Available The longitudinal vibration of the ship shaft system is the one of the most important factors of hull stern vibration, and it can be effectively minimized by installing a longitudinal vibration absorber. In this way, the vibration and noise of ships can be brought under control. However, the parameters of longitudinal vibration absorbers have a great influence on the vibration characteristics of the shaft system. As such, a certain shafting testing platform was studied as the object on which a finite model was built, and the relationship between longitudinal stiffness and longitudinal vibration in the shaft system was analyzed in a straight alignment state. Furthermore, a longitudinal damping model of the shaft system was built in which the parameters of the vibration absorber were non-dimensionalized, the weight of the vibration absorber was set as a constant, and an optimizing algorithm was used to calculate the optimized stiffness and damping coefficient of the vibration absorber. Finally, the longitudinal vibration frequency response of the shafting testing platform before and after optimizing the parameters of the longitudinal vibration absorber were compared, and the results indicated that the longitudinal vibration of the shafting testing platform was decreased effectively, which suggests that it could provide a theoretical foundation for the parameter optimization of longitudinal vibration absorbers.

Treatability study of absorbent polymer waste form for mixed waste treatment

International Nuclear Information System (INIS)

Herrmann, S. D.; Lehto, M. A.; Stewart, N. A.; Croft, A. D.; Kern, P. W.

2000-01-01

A treatability study was performed to develop and characterize an absorbent polymer waste form for application to low level (LLW) and mixed low level (MLLW) aqueous wastes at Argonne National Laboratory-West (ANL-W). In this study absorbent polymers proved effective at immobilizing aqueous liquid wastes in order to meet Land Disposal Restrictions for subsurface waste disposal. Treatment of aqueous waste with absorbent polymers provides an alternative to liquid waste solidification via high-shear mixing with clays and cements. Significant advantages of absorbent polymer use over clays and cements include ease of operations and waste volume minimization. Absorbent polymers do not require high-shear mixing as do clays and cements. Granulated absorbent polymer is poured into aqueous solutions and forms a gel which passes the paint filter test as a non-liquid. Pouring versus mixing of a solidification agent not only eliminates the need for a mixing station, but also lessens exposure to personnel and the potential for spread of contamination from treatment of radioactive wastes. Waste minimization is achieved as significantly less mass addition and volume increase is required of and results from absorbent polymer use than that of clays and cements. Operational ease and waste minimization translate into overall cost savings for LLW and MLLW treatment

Ribonucleic artefacts: are some extracellular RNA discoveries driven by cell culture medium components?

Science.gov (United States)

Tosar, Juan Pablo; Cayota, Alfonso; Eitan, Erez; Halushka, Marc K; Witwer, Kenneth W

2017-01-01

In a recently published study, Anna Krichevsky and colleagues raise the important question of whether results of in vitro extracellular RNA (exRNA) studies, including extracellular vesicle (EV) investigations, are confounded by the presence of RNA in cell culture medium components such as foetal bovine serum (FBS). The answer, according to their data, is a resounding "yes". Even after lengthy ultracentrifugation to remove bovine EVs from FBS, the majority of exRNA in FBS remained. Although technical factors may affect the degree of depletion, residual EVs and exRNA in FBS could influence the conclusions of in vitro studies: certainly, for secreted RNA, and possibly also for cell-associated RNA. In this commentary, we critically examine some of the literature in this field, including a recent study from some of the authors of this piece, in light of the Wei et al. study and explore how cell culture-derived RNAs may affect what we think we know about EV RNAs. These findings hold particular consequence as the field moves towards a deeper understanding of EV-RNA associations and potential functions.

'That proves my point': How mediums reconstrue disconfirmation in medium-sitter interactions.

Science.gov (United States)

Enoksen, Anette Einan; Dickerson, Paul

2018-04-01

Previous research has examined how the talk of mediums attends to the epistemological status of their readings. Such work has identified that mediums frequently use question-framed propositions that are typically confirmed by the sitter, thereby conferring epistemological status on the medium. This study seeks to investigate what happens when the sitter disconfirms the propositions of the medium. The study focuses on the ways in which such disconfirmation can be responded to such that it is reconstrued as evidence of the psychic nature of the medium's reading. Televised demonstrations of psychic readings involving British and US mediums and their sitters are analysed. The results suggest that mediums rework disconfirmation as proof in several ways: first, by emphasizing the different access that sitter and medium have to knowledge (e.g., about the future); second, as evidence that the medium has access to the actual voice of the deceased (and may therefore mishear what the deceased has said to them); and third, as revealing an important truth that has hitherto been concealed from the sitter. The implications of these findings are considered for cases where speakers bring different and potentially competing, epistemological resources to an interaction. © 2018 The British Psychological Society.

Development of simulation approach for two-dimensional chiral molecular self-assembly driven by hydrogen bond at the liquid/solid interface

Science.gov (United States)

Qin, Yuan; Yao, Man; Hao, Ce; Wan, Lijun; Wang, Yunhe; Chen, Ting; Wang, Dong; Wang, Xudong; Chen, Yonggang

2017-09-01

Two-dimensional (2D) chiral self-assembly system of 5-(benzyloxy)-isophthalic acid derivative/(S)-(+)-2-octanol/highly oriented pyrolytic graphite was studied. A combined density functional theory/molecular mechanics/molecular dynamics (DFT/MM/MD) approach for system of 2D chiral molecular self-assembly driven by hydrogen bond at the liquid/solid interface was thus proposed. Structural models of the chiral assembly were built on the basis of scanning tunneling microscopy (STM) images and simplified for DFT geometry optimization. Merck Molecular Force Field (MMFF) was singled out as the suitable force field by comparing the optimized configurations of MM and DFT. MM and MD simulations for hexagonal unit model which better represented the 2D assemble network were then preformed with MMFF. The adhesion energy, evolution of self-assembly process and characteristic parameters of hydrogen bond were obtained and analyzed. According to the above simulation, the stabilities of the clockwise and counterclockwise enantiomorphous networks were evaluated. The calculational results were supported by STM observations and the feasibility of the simulation method was confirmed by two other systems in the presence of chiral co-absorbers (R)-(-)-2-octanol and achiral co-absorbers 1-octanol. This theoretical simulation method assesses the stability trend of 2D enantiomorphous assemblies with atomic scale and can be applied to the similar hydrogen bond driven 2D chirality of molecular self-assembly system.

Development of Coatings for Radar Absorbing Materials at X-band

Science.gov (United States)

Kumar, Abhishek; Singh, Samarjit

2018-03-01

The present review gives a brief account on some of the technical features of radar absorbing materials (RAMs). The paper has been presented with a concentrated approach towards the material aspects for achieving enhanced radar absorption characteristics for its application as a promising candidate in stealth technology and electromagnetic interference (EMI) minimization problems. The effect of metal particles doping/dispersion in the ferrites and dielectrics has been discussed for obtaining tunable radar absorbing characteristics. A short theoretical overview on the development of absorber materials, implementation of genetic algorithm (GA) in multi-layering and frequency selective surfaces (FSSs) based multi-layer has also been presented for the development of radar absorbing coatings for achieving better absorption augmented with broadband features in order to counter the radar detection systems.

Tunable enhanced optical absorption of graphene using plasmonic perfect absorbers

Energy Technology Data Exchange (ETDEWEB)

Cai, Yijun [Institute of Optoelectronic Technology, Department of Electronic Engineering, Xiamen University, Xiamen 361005 (China); Institute of Electromagnetics and Acoustics, Department of Electronic Science, Xiamen University, Xiamen 361005 (China); Zhu, Jinfeng, E-mail: nanoantenna@hotmail.com [Institute of Electromagnetics and Acoustics, Department of Electronic Science, Xiamen University, Xiamen 361005 (China); Liu, Qing Huo [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)

2015-01-26

Enhancement and manipulation of light absorption in graphene is a significant issue for applications of graphene-based optoelectronic devices. In order to achieve this purpose in the visible region, we demonstrate a design of a graphene optical absorber inspired by metal-dielectric-metal metamaterial for perfect absorption of electromagnetic waves. The optical absorbance ratios of single and three atomic layer graphene are enhanced up to 37.5% and 64.8%, respectively. The graphene absorber shows polarization-dependence and tolerates a wide range of incident angles. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

An experimental study of an energy absorbing restrainer for piping systems

International Nuclear Information System (INIS)

Sone, A.; Suzuki, K.

1989-01-01

Recently, in the seismic design methodology of the piping systems in nuclear power plants, new and improved design criteria and calculation techniques which will lead to more reliable and cost saving design products have been investigated. For instance, problems for reducing the snubbers in nuclear power plants which provide high costs for their inspections and maintenances and related flexible design problems for the dynamic piping systems have been investigated. Thus, in order to replace snubbers, various types of alternative supporting devices such as dynamic absorbers, gapped support and energy absorbing support devices have been proposed. A number of energy absorbing restrainers have been designed in Japan and United-States by allowing yield to occur during strong earthquakes. Advantages and disadvantages of these restrainers were examined analytically and experimentally. In order to overcome the disadvantages, the authors introduced new absorbing material LSPZ (laminated super plastic zinc) in which SPZ is expected to have reliable ductility and also efficient energy absorbability still under the normal temperature condition. This paper is devoted to an experimental works for this updated absorbing restrainer

Origami-inspired metamaterial absorbers for improving the larger-incident angle absorption

International Nuclear Information System (INIS)

Shen, Yang; Pang, Yongqiang; Wang, Jiafu; Ma, Hua; Pei, Zhibin; Qu, Shaobo

2015-01-01

When a folded resistive patch array stands up on a metallic plane, it can exhibit more outstanding absorption performance. Our theoretical investigations and simulations demonstrated that the folded resistive patch arrays can enhance the absorption bandwidth progressively with the increase of the incident angle for the oblique transverse magnetic incidence, which is contrary to the conventional resistive frequency selective surface absorber. On illumination, we achieved a 3D structure metamaterial absorber with the folded resistive patches. The proposed absorber is obtained from the inspiration of the origami, and it has broadband and lager-incident angle absorption. Both the simulations and the measurements indicate that the proposed absorber achieves the larger-incident angle absorption until 75° in the frequency band of 3.6–11.4 GHz. In addition, the absorber is extremely lightweight. The areal density of the fabricated sample is about 0.023 g cm −2 . Due to the broadband and lager-incident angle absorption, it is expected that the absorbers may find potential applications such as stealth technologies and electromagnetic interference. (paper)

THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z ∼< 1

International Nuclear Information System (INIS)

Lehner, N.; Howk, J. C.; Tripp, T. M.; Tumlinson, J.; Thom, C.; Fox, A. J.; Prochaska, J. X.; Werk, J. K.; O'Meara, J. M.; Ribaudo, J.

2013-01-01

We assess the metal content of the cool (∼10 4 K) circumgalactic medium (CGM) about galaxies at z ∼ H I ∼ H I selection avoids metallicity biases inherent in many previous studies of the low-redshift CGM. We compare the column densities of weakly ionized metal species (e.g., O II, Si II, Mg II) to N H I in the strongest H I component of each absorber. We find that the metallicity distribution of the LLS (and hence the cool CGM) is bimodal with metal-poor and metal-rich branches peaking at [X/H] ≅ –1.6 and –0.3 (or about 2.5% and 50% solar metallicities). The cool CGM probed by these LLS is predominantly ionized. The metal-rich branch of the population likely traces winds, recycled outflows, and tidally stripped gas; the metal-poor branch has properties consistent with cold accretion streams thought to be a major source of fresh gas for star forming galaxies. Both branches have a nearly equal number of absorbers. Our results thus demonstrate there is a significant mass of previously undiscovered cold metal-poor gas and confirm the presence of metal enriched gas in the CGM of z ∼< 1 galaxies.

Design and testing of a shock absorber for a type I container

International Nuclear Information System (INIS)

Sappok, M.; Beine, B.; Rittscher, D.; Jais, M.

1994-01-01

A simple method of designing a shock absorber to protect a type B cast-iron container is developed. The results of deformation tests of the structural material (steel pipes) used for the shock absorber are presented. The accelerations and strains measured during the 9m drop tests of the container with the shock absorber are compared with the theoretical results of the calculations for the shock absorber design. ((orig.))

Absorbed dose modeled for a liquid circulating around a Co-60 irradiator

International Nuclear Information System (INIS)

Mangussi, J.

2013-01-01

A model for the distribution of the absorbed dose in a volume of liquid circulating into an active tank containing a Co-60 irradiator is presented. The absorbed dose, the stir process and the liquid recirculation into the active tank are modeled. The absorbed dose for different fractions of the volume is calculated. The necessary irradiation times for the achievement of the required absorbed dose are evaluated. (author)

Specification of absorbed dose for reporting a therapeutic irradiation

International Nuclear Information System (INIS)

Wambersie, A.; Chassagne, D.

1981-01-01

The problem of dose specification in external beam therapy with photons and electrons has been dealt with in ICRU Report 29 (1978). This problem arises from the fact that the absorbed dose distribution is usually not uniform in the target volume and that for the purpose of treatment reporting a nominal absorbed dose - which will be called target absorbed dose - has to be selected. When comparing the clinical results obtained between radiotherapy centres, the differences in the reported target absorbed doses which can be introduced by differences in the methods of dose specification often are much larger than the differences related to the dosimetric procedures themselves. This shows the importance of the problem. In this paper, some definitions of terms and concepts currently used in radiotherapy are first recalled: tumour volume, target volume, treatment volume, etc. These definitions have been proposed in ICRU Report 29 for photon and electron beams; they can be extended to any kind of irradiation. For external beam therapy with photons and electrons, the target absorbed dose is defined as the absorbed dose at selected point(s) (specification point(s)) having a meaningful relation to the target volume and/or the irradiation beams. Examples are discussed for typical cases. As far as interstitial and intracavitary therapy is concerned, the problem is more complex and no recommendations have so far been made by the ICRU Commission. A major difficulty arises from the sharp dose gradient as a function of the distance to the sources. The particular case of the treatment of cervix carcinoma is considered and some possible methods of specification are discussed: (1) the indication of the sources (in adequate units) and the duration of the application, (2) the absorbed doses at selected reference points (bladder, rectum, bony structures) and (3) the description of the tissue volume (height, width, thickness) encompassed by a given isodose surface (60Gy). (author)

Visualization and simulation of density driven convection in porous media using magnetic resonance imaging

Science.gov (United States)

Montague, James A.; Pinder, George F.; Gonyea, Jay V.; Hipko, Scott; Watts, Richard

2018-05-01

Magnetic resonance imaging is used to observe solute transport in a 40 cm long, 26 cm diameter sand column that contained a central core of low permeability silica surrounded by higher permeability well-sorted sand. Low concentrations (2.9 g/L) of Magnevist, a gadolinium based contrast agent, produce density driven convection within the column when it starts in an unstable state. The unstable state, for this experiment, exists when higher density contrast agent is present above the lower density water. We implement a numerical model in OpenFOAM to reproduce the observed fluid flow and transport from a density difference of 0.3%. The experimental results demonstrate the usefulness of magnetic resonance imaging in observing three-dimensional gravity-driven convective-dispersive transport behaviors in medium scale experiments.

Generalized pin factor methodology for LWR reload cores with discrete burnable absorbers

International Nuclear Information System (INIS)

Hah, C.J.; Hideki Matsumoto; Toshikazu Ida; Lee, C.; Chao, Y.A.

2005-01-01

Discrete burnable absorbers are used to suppress excess reactivity as well as peak pin power in an assembly. After the burn-out of absorption material, discrete burnable absorbers are usually removed from assembly guide tubes for the next cycle. For that case, the pin factors with discrete burnable absorbers cannot be used since the assembly configuration is physically changed. The pin factors without discrete burnable absorbers also have noticeable deviation from the actual case because they do not take into account the history effect due to the residence of discrete burnable absorbers for the previous cycle. In this paper, the generalized pin factor (GPF) method is developed to accurately predict pin powers by considering the history effect. The method uses a second-order polynomial function to approximate the history effect which builds up during the residence of burnable absorber material and employs a linear approximation to simulate the decay of the history effect after discrete burnable absorbers are removed. The verification results from Westinghouse Vantage- 5H assemblies with WABAs showed that pin power errors were significantly reduced by using the GPF. (authors)

Absorbed Energy in Ship Collisions and Grounding

DEFF Research Database (Denmark)

Pedersen, Preben Terndrup; Zhang, Shengming

1998-01-01

is that the absorbed energy does not depend on the arrangement of the structure, the material properties, and the damage mode.The purpose of the present paper is to establish a new simple relation between the absorbed energy and the destroyed material volume, which can be used as a design tool for analysis of ship...... collisions and grounding. The developed expressions reflect the structural arrangement, the material properties and different damage patterns.The present method is validated against a large number of existing experimental results and detailed numerical simulation results. Applications to full-sale ship...

Neutron absorbers, and the production method

International Nuclear Information System (INIS)

Kayano, Hideo; Yajima, Seishi; Oono, Hironori.

1979-01-01

Purpose: To integrally sinter a metal powder and a metal network material thereby to obtain a material having a high neutron absorbing function, an excellent corrosion resistance and an excellent oxidation resistance. Method: An element having a high neutron absorbing function, such as Gd, or a compound thereof and a powder of a metal having excellent corrosion resistance, oxidation resistance and ductility, such as Fe, Cr or the like are uniformly mixed with each other. In a case where a substance having a neutron absorbing function is a hydroxide an organic complex or the like, it is formed into a gel-like substance and mixed uniformly with the metal powder, the gel-like substance being pasted, and covered on the surface of the metal powder and dried. Then, the mixture or the dry coated material is extended and the metal network material having excellent corrosion resistance, oxidation resistance and ductility is covered or interposed or between at least one layer of upper, intermediate or lower layers of said laminated material, and thereafter is subjected to cold or hot rolling, and then sintered and furthermore rolled, if necessary, the thus treated material being burned in vacuum or a non-oxidizing atmosphere. (Kamimura, M.)

Calirimeter/absorber optimization for a RHIC dimuon experiment

Energy Technology Data Exchange (ETDEWEB)

Aronson, S.H.; Murtagh, M.J.; Starks, M. [Brookhaven National Lab., Upton, NY (United States); Liu, X.T.; Petitt, G.A.; Zhang, Z. [Georgia State Univ., Atlanta (United States); Ewell, L.A.; Hill, J.C.; Wohn, F.K. [Iowa State Univ., Ames (United States); Costales, J.B.; Namboodiri, M.N., Sangster, T.C.; Thomas, J.H. [Lawrence Livermore National Lab., CA (United States); Gavron, A.; Waters, L. [Los Alamos National Lab., NM (United States); Kehoe, W.L.; Steadman, S.G. [Massachusetts Institute of Technology, Cambridge (United States); Awes, T.C.; Obenshain, F.E.; Saini, S.; Young, G.R. [Oak Ridge National Lab., TN (United States); Chang, J.; Fung, S.Y.; Kang, J.H. [Univ. of California, Riverside, CA (United States); Kreke, J.; He, Xiaochun, Sorensen, S.P. [Univ. of Tennessee, Knoxville (United States); Cornell, E.C.; Maguire, C.F. [Vanderbilt Univ., Nashville, TN (United States)

1991-12-31

The RD-10 R&D effort on calorimeter/absorber optimization for a RHIC experiment had an extended run in 1991 using the A2 test beam at the AGS. Measurements were made of the leakage of particles behind various model hadron calorimeters. Behavior of the calorimeter/absorber as a muon-identifier was studied. First comparisons of results from test measurements to calculated results using the GHEISHA code were made

A reflective-backing-free metamaterial absorber with broadband response

Directory of Open Access Journals (Sweden)

Cuilian Xu

2017-06-01

Full Text Available In this paper, we propose a polarization-independent and broadband perfect infrared (IR metamaterial absorber (MA without reflective backing. The proposed absorber is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones which can absorb 80% EM wave from 50.70 to 81.87THz, while transmit 80% EM wave from 0 to 37.71THz. With the decreasing of frequency, the transmissivity increases, which is close to 100% from 0 to 5THz. We can broaden the absorption bandwidth of the MA by cascading multi-layers truncated cones. Furthermore, the proposed IR MA promises to be one desirable stealth material for radar-IR compatibility.

A neutron-absorbing porcelain enamel for coating nuclear equipment

International Nuclear Information System (INIS)

Iverson, D.C.

1988-01-01

In 1985, nuclear safety analyses showed that under upset conditions, strict administrative controls were necessary to limit access to a new processing vessel for enriched uranium service at the Savannah River Plant (SRP). In order to increase the level of nuclear safety associated with that vessel, the traditional methods of incorporating neutron absorbers (borated stainless steel, boral, cadmium foil, etc.) were reviewed, however, process conditions did not permit their use. A neutron-absorbing porcelain enamel containing large amounts of cadmium and boron was developed as a safe, cost-effective alternative to traditional neutron-absorbing methods. Several pieces of coated process equipment have been installed or are planned for installation at SRP

Parotid-Absorbed Doses: A Comparison Between Spiral Tomography and Panoramic

Directory of Open Access Journals (Sweden)

Ehsan Hekmatian

2016-07-01

Full Text Available Background Jaws spiral tomography and panoramic radiography have wide applications in dentistry, and the parotid gland is one of the most sensitive organs of the head and neck. Objectives The aim of this study was to evaluate and compare the parotid-absorbed dose in spiral tomography and panoramic radiographs using a thermoluminescent dosimeter. Materials and Methods A radiation analog dosimetry phantom was placed in a Cranex Tome radiograph device, and a parotid absorbed dose was measured in both techniques. Thermoluminescent dosimeters were placed bilaterally in the parotid region (on the tube side and the opposite side. Spiral tomography dosimetry was done for the upper and lower jaws in the anterior and posterior regions. Each region contained four slices of 2 mm and four slices of 4 mm in thickness. The results were analyzed by a Wilcoxon test. Results For the tube side parotid, the average absorbed doses in spiral tomography of the anterior and posterior parts of the maxilla and mandible, with the 2 mm slice thickness, were 1.70/1.40 and 1.65/1.60 mGy, respectively. The average absorbed doses with the 4mm slices were 1.65/1.70 and 1.75/1.57 mGy, respectively. For the opposite parotid, the average absorbed dose in spiral tomography of the anterior and posterior parts of the maxilla and mandible, with the 2 mm slice thickness, were 1.40/1.30 and 1.40/1.67 mGy, respectively. The average absorbed doses with the 4mm slices were 1.50/1.66 and 1.40/1.50 mGy, respectively. The average absorbed dose of the panoramic radiograph was 1.40 mGy. Conclusions There was no statistically significant difference in the parotid absorbed dose between spiral tomography and a panoramic radiograph (P value = 0.18. The overall results of this study were similar to other studies.

The measurement of the indoor absorbed dose rate in air in Beijing

International Nuclear Information System (INIS)

Guo Mingqiang; Pan Ziqiang; Yi Nanchang; Wei Zemin; Zhang Chao; Wang Huamin; Zhu Wencai

1985-01-01

This paper describes the indoor absorbed dose rate in air in Beijing. The average indoor absorbed dose rate in air is 8.29 μrad/h. The ratio of indoor to outdoor absorbed dose rate for 849 buildings is 1.51

Simulated mixed absorbers and effective atomic numbers for γ ...

Indian Academy of Sciences (India)

The total -ray interaction crosss-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for -ray absorption under narrow beam good geometry set-up. The measurements were taken for the combination of metallic absorbers like aluminium, copper, lead and mercury ...

Fabrication of selective solar absorbers using pulsed laser deposition

CSIR Research Space (South Africa)

Yalisi, B

2009-06-01

Full Text Available Selective solar absorbers are devices that have been designed to absorb as much as possible of the solar radiation which is in the wavelength range of 0.3 to 2.5 µm and to minimise thermal emittance in the wavelength range from 2.5µm to the far...

Properties of InGaAs quantum dot saturable absorbers in monolithic mode-locked lasers

DEFF Research Database (Denmark)

Thompson, M.G.; Marinelli, C.; Chu, Y.

Saturable absorbers properties are characterised in monolithic mode-locked InGaAs quantum dot lasers. We analyse the impact of weak quantum confined Stark effect, fast absorber recovery time and low absorber saturation power on the mode-locking performance.......Saturable absorbers properties are characterised in monolithic mode-locked InGaAs quantum dot lasers. We analyse the impact of weak quantum confined Stark effect, fast absorber recovery time and low absorber saturation power on the mode-locking performance....

Development of highly effective neutron shields and neutron absorbing materials

International Nuclear Information System (INIS)

Tsuda, K.; Matsuda, F.; Taniuchi, H.; Yuhara, T.; Iida, T.

1993-01-01

A wide range of materials, including polymers and hydrogen-occluded alloys that might be usable as the neutron shielding material were examined. And a wide range of materials, including aluminum alloys that might be usable as the neutron-absorbing material were examined. After screening, the candidate material was determined on the basis of evaluation regarding its adaptabilities as a high-performance neutron-shielding and neutron-absorbing material. This candidate material was manufactured for trial, after which material properties tests, neutron-shielding tests and neutron-absorbing tests were carried out on it. The specifications of this material were thus determined. This research has resulted in materials of good performance; a neutron-shielding material based on ethylene propylene rubber and titanium hydride, and a neutron-absorbing material based on aluminum and titanium hydride. (author)

Effectiveness of KNIFC-PAN Resin in Absorbing Radiocesium in Seawater

International Nuclear Information System (INIS)

Nurrul Assyikeen Mohd Jaffary; Abdul Kadir Ishak; Zal Uyun Wan Mahmood; Wo, Y.M.; Norfaizal Mohamed; Mohd Tarmizi Ishak

2016-01-01

The effectiveness of KNiFC-PAN absorber, potassium-nickel hexacyanoferrate (II) (KNiFC) bound into modified polyacrylonitrile (PAN) have been tested for capability in absorbing radiocesium in seawater samples. The efficiency of the KNiFC-PAN were measured by the different activity of the radiocesium measured using Hyper Pure Germanium Detector (HPGe) in initial spiked seawater and eluent seawater after passed through 5 ml of KNiFC absorber. Study showed 87 % effectiveness of the KNiFC-PAN in absorbing radiocesium. Further study conducted to illustrate relation between spiked seawater and activity measured for 5 ml of KniFC passed through spiked seawater in packed column. This study suggested this relative 15L cubitainer method can be used to monitor the radiocesium in emergency situation for the fast and reliable result. (author)

Effect of the time spent by the photon in the absorbed state on the time-dependent transfer of radiation

International Nuclear Information System (INIS)

Rao, D.M.; Rangarajan, K.E.; Peraiah, A.

1990-01-01

The time-dependent transfer equation is derived for a two-level atomic model which takes both bound-bound and bound-free transitions into account. A numerical scheme is proposed for solving the monochromatic time-dependent transfer equation when the time spent by the photon in the absorbed state is significant. The method can be easily extended to solve the problem of time-dependent line formation of the bound-free continuum. It is used here to study three types of boundary conditions of the incident radiation incident on a scattering atmosphere. The quantitative results show that the relaxation of the radiation field depends on the optical depth of the medium and on the ray's angle of emergence. 21 refs

Absorbed fractions for alpha particles in ellipsoidal volumes

International Nuclear Information System (INIS)

Amato, Ernesto; Baldari, Sergio; Italiano, Antonio

2013-01-01

Internal dosimetry of alpha particles is gaining attention due to the increasing applications in cancer treatment and also for the assessment of environmental contamination from radionuclides. We developed a Monte Carlo simulation in GEANT4 in order to calculate the absorbed fractions for monoenergetic alpha particles in the energy interval between 0.1 and 10 MeV, uniformly distributed in ellipsoids made of soft tissue. For each volume, we simulated a spherical shape, three oblate and three prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a ‘generalized radius’ was found; and the dependence of the fit parameters on the alpha energy is discussed and fitted by parametric functions. With the proposed formulation, the absorbed fraction for alpha particles in the energy range explored can be calculated for volumes and for ellipsoidal shapes of practical interest. This method can be applied to the evaluation of absorbed fraction from alpha-emitting radionuclides. The contribution to the deposited energy coming from electron and photon emissions can be accounted for exploiting the specific formulations previously introduced. As an example of application, the dosimetry of 213 Bi and its decay chain in ellipsoids is reported. (paper)

MAGIICAT III. Interpreting self-similarity of the circumgalactic medium with virial mass using Mg II absorption

International Nuclear Information System (INIS)

Churchill, Christopher W.; Trujillo-Gomez, Sebastian; Nielsen, Nikole M.; Kacprzak, Glenn G.

2013-01-01

In Churchill et al., we used halo abundance matching applied to 182 galaxies in the Mg II Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean Mg II λ2796 equivalent width follows a tight inverse-square power law, W r (2796)∝(D/R vir ) –2 , with projected location relative to the galaxy virial radius and that the Mg II absorption covering fraction is effectively invariant with galaxy virial mass, M h , over the range 10.7 ≤ log M h /M ☉ ≤ 13.9. In this work, we explore multivariate relationships between W r (2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T = 10 4 -10 4.5 K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the Mg II absorbing gas such that the mean W r (2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D ≅ 0.3 R vir , independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3 < D/R vir ≤ 1, the mean W r (2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W r (2796) and virial mass. We discuss how simulations and theory constrained by observations support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.

MAGIICAT III. Interpreting self-similarity of the circumgalactic medium with virial mass using Mg II absorption

Energy Technology Data Exchange (ETDEWEB)

Churchill, Christopher W.; Trujillo-Gomez, Sebastian; Nielsen, Nikole M. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia)

2013-12-10

In Churchill et al., we used halo abundance matching applied to 182 galaxies in the Mg II Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean Mg II λ2796 equivalent width follows a tight inverse-square power law, W{sub r} (2796)∝(D/R {sub vir}){sup –2}, with projected location relative to the galaxy virial radius and that the Mg II absorption covering fraction is effectively invariant with galaxy virial mass, M {sub h}, over the range 10.7 ≤ log M {sub h}/M {sub ☉} ≤ 13.9. In this work, we explore multivariate relationships between W{sub r} (2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T = 10{sup 4}-10{sup 4.5} K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the Mg II absorbing gas such that the mean W{sub r} (2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D ≅ 0.3 R {sub vir}, independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3 < D/R {sub vir} ≤ 1, the mean W{sub r} (2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W{sub r} (2796) and virial mass. We discuss how simulations and theory constrained by observations support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.

Superlattice photonic crystal as broadband solar absorber for high temperature operation.

Science.gov (United States)

Rinnerbauer, Veronika; Shen, Yichen; Joannopoulos, John D; Soljačić, Marin; Schäffler, Friedrich; Celanovic, Ivan

2014-12-15

A high performance solar absorber using a 2D tantalum superlattice photonic crystal (PhC) is proposed and its design is optimized for high-temperature energy conversion. In contrast to the simple lattice PhC, which is limited by diffraction in the short wavelength range, the superlattice PhC achieves solar absorption over broadband spectral range due to the contribution from two superposed lattices with different cavity radii. The superlattice PhC geometry is tailored to achieve maximum thermal transfer efficiency for a low concentration system of 250 suns at 1500 K reaching 85.0% solar absorptivity. In the high concentration case of 1000 suns, the superlattice PhC absorber achieves a solar absorptivity of 96.2% and a thermal transfer efficiency of 82.9% at 1500 K, amounting to an improvement of 10% and 5%, respectively, versus the simple square lattice PhC absorber. In addition, the performance of the superlattice PhC absorber is studied in a solar thermophotovoltaic system which is optimized to minimize absorber re-emission by reducing the absorber-to-emitter area ratio and using a highly reflective silver aperture.

Convection-type LH{sub 2} absorber R and D for muon ionization cooling

Energy Technology Data Exchange (ETDEWEB)

Ishimoto, S. E-mail: shigeru.ishimoto@kek.jp; Bandura, L.; Black, E.L.; Boghosian, M.; Cassel, K.W.; Cummings, M.A.; Darve, C.; Dyshkant, A.; Errede, D.; Geer, S.; Haney, M.; Hedin, D.; Johnson, R.; Johnstone, C.J.; Kaplan, D.M.; Kubik, D.; Kuno, Y.; Majewski, S.; Popovic, M.; Reep, M.; Summers, D.; Suzuki, S.; Yoshimura, K

2003-05-01

A feasibility study on liquid hydrogen (LH{sub 2}) absorbers for muon ionization cooling is reported. In muon ionization cooling, an LH{sub 2} absorber is required to have a high cooling power greater than 100 W to cool heat deposited by muons passing through. That heat in LH{sub 2} can be removed at either external or internal heat exchangers, which are cooled by cold helium gas. As one of the internal heat exchanger types, a convection-type absorber is proposed. In the convection-type absorber, heat is taken away by the convection of LH{sub 2} in the absorber. The heat exchanger efficiency for the convection-type absorber is calculated. A possible design is presented.

Design and measuring of a tunable hybrid metamaterial absorber for terahertz frequencies

Science.gov (United States)

Zhong, Min; Liu, Shui Jie; Xu, Bang Li; Wang, Jie; Huang, Hua Qing

2018-04-01

A tunable hybrid metamaterial absorber is designed and experimentally produced in THz band. The hybrid metamaterial absorber contains two dielectric layers: SU-8 and VO2 layers. An absorption peak reaching to 83.5% is achieved at 1.04 THz. The hybrid metamaterial absorber exhibits high absorption when the incident angle reaches to 45°. Measured results indicate that the absorption amplitude and peak frequency of the hybrid metamaterial absorber is tunable in experiments. It is due to the insulator-to-metal phase transition is achieved when the measured temperature reaches to 68 °C. Moreover, the hybrid metamaterial absorber reveals high figure of merit (FOM) value when the measured temperature reaches to 68 °C.

Investigation of a Shock Absorber for Safeguard of Fuel Assemblies Failure

International Nuclear Information System (INIS)

Karalevicius, Renatas; Dundulis, Gintautas; Rimkevicius, Sigitas; Uspuras, Eugenijus

2006-01-01

The Ignalina NPP has two reactors. The Unit 1 was shut down, therefore the special equipment was designed for transportation of the fuel from Unit 1 to Unit 2. The fuel-loaded basket can drop during transportation. The special shock absorber was designed in order to avoid failure of fuel assemblies during transportation. In case of drop of fuel loaded basket, the failure of fuel assemblies can occur. This shock absorber was studied by scaled experiments at Lithuanian Energy Institute. Static and dynamic investigations of shock absorber are presented in this paper, including dependency of axial force versus axial compression. The finite element codes BRIGADE/Plus and ABAQUS/Explicit were used for analysis. Static simulation was used to optimize the dimensions of shock absorber. Dynamic analysis shows that shock absorber is capable to withstand the dynamic load for successful force suppression function in case of an accident. (authors)

The Magnetically Driven Direct Drive Approach to Ignition: Responses to Questions by Panel 1 of the FY15 ICF Program Review.

Energy Technology Data Exchange (ETDEWEB)

Sinars, Daniel [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2015-07-01

The long-term goal of the pulsed-­power based, magnetically driven target approach is to achieve high single­shot yields (0.5-­1 GJ per shot). This goal may take decades to achieve, but if successful we believe it would be a key capability for the Stockpile Stewardship program, as noted as far back as 1988 in the Laboratory Microfusion Capability Phase 1 (U) study. If this approach is successful, it may be possible to achieve these yields from targets absorbing up to 10 MJ in a laboratory pulsed power facility with a stored energy of roughly 130 MJ. Such a facility would be substantially cheaper, and not as complex, than the corresponding pulsed power facility required for producing comparable yields from x-ray driven capsule targets.

The Anatomy of Medium-Scale Farm Growth in Zambia: What Are the Implications for the Future of Smallholder Agriculture?

Directory of Open Access Journals (Sweden)

Nicholas Sitko

2015-09-01

Full Text Available Lost in the debates about the appropriate scale of production to promote agricultural growth in Africa is the rapid expansion of medium-scale farmers. Using Zambia as a case study, this article explores the causes and consequences of this middle-tier transformation on the future of small-scale agriculture. Combining political economic analysis with household survey data, this article examines the relationships between the growth in medium-scale farmers and changing conditions of land access, inequality, and alienation for small-scale farmers. Growth of medium-scale farmers is associated with high land inequality and rapid land alienation in high potential agricultural areas. This growth is shown to be partially driven by wage earner investment in land acquisition and is leading to substantial under-utilization of agricultural land. These processes are both limiting agricultural growth potential and foreclosing future options for an inclusive agricultural development strategy.

Finite volume method for radiative heat transfer in an unstructured flow solver for emitting, absorbing and scattering media

International Nuclear Information System (INIS)

Gazdallah, Moncef; Feldheim, Véronique; Claramunt, Kilian; Hirsch, Charles

2012-01-01

This paper presents the implementation of the finite volume method to solve the radiative transfer equation in a commercial code. The particularity of this work is that the method applied on unstructured hexahedral meshes does not need a pre-processing step establishing a particular marching order to visit all the control volumes. The solver simply visits the faces of the control volumes as numbered in the hexahedral unstructured mesh. A cell centred mesh and a spatial differencing step scheme to relate facial radiative intensities to nodal intensities is used. The developed computer code based on FVM has been integrated in the CFD solver FINE/Open from NUMECA Int. Radiative heat transfer can be evaluated within systems containing uniform, grey, emitting, absorbing and/or isotropically or linear anisotropically scattering medium bounded by diffuse grey walls. This code has been validated for three test cases. The first one is a three dimensional rectangular enclosure filled with emitting, absorbing and anisotropically scattering media. The second is the differentially heated cubic cavity. The third one is the L-shaped enclosure. For these three test cases a good agreement has been observed when temperature and heat fluxes predictions are compared with references taken, from literature.

Neutron absorbing room temperature vulcanizable silicone rubber compositions

International Nuclear Information System (INIS)

Zoch, H.L.

1979-01-01

A neutron absorbing composition is described and consists of a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide. 20 claims

Process and device for exchanging neutron absorber rods

International Nuclear Information System (INIS)

Baero, G.; Kraus, W.; Stindt, W.

1987-01-01

The control element repair device contains lifting equipment for inserting the control element in the accommodation device. Due to the case position assigned to each absorber rod of a control element, after removing the carrier with the absorber rods fixed to it, the defective rods can be replaced by new ones. The accommodation device has a support to support the carrier. Turning the control element for the PWR through 180 0 is prevented. (DG) [de

Optical architecture design for detection of absorbers embedded in visceral fat.

Science.gov (United States)

Francis, Robert; Florence, James; MacFarlane, Duncan

2014-05-01

Optically absorbing ducts embedded in scattering adipose tissue can be injured during laparoscopic surgery. Non-sequential simulations and theoretical analysis compare optical system configurations for detecting these absorbers. For absorbers in deep scattering volumes, trans-illumination is preferred instead of diffuse reflectance. For improved contrast, a scanning source with a large area detector is preferred instead of a large area source with a pixelated detector.

Carbon Nanomaterials for Optical Absorber Applications

Directory of Open Access Journals (Sweden)

Anupama KAUL

2011-12-01

Full Text Available Optical absorbers based on vertically aligned multi-walled carbon nanotubes (MWCNTs, synthesized using electric-field assisted growth, are described here that show an ultra-low reflectance, 100X lower compared to the benchmark, a diffuse metal black - Au-black - from wavelength l ~ 350 nm – 2500 nm. The reflectance of the MWCNT arrays was measured to be as low as 0.02 % at 2 mm in the infra-red (IR. Growth conditions were optimized for the realization of high-areal density arrays of MWCNTs using a plasma-based chemical vapor deposition (CVD process. Such high efficiency absorbers are particularly attractive for radiometry, as well as energy harnessing applications. Optical modeling calculations were conducted that enabled a determination of the extinction coefficient in the films.

Fault Detection for Automotive Shock Absorber

Science.gov (United States)

Hernandez-Alcantara, Diana; Morales-Menendez, Ruben; Amezquita-Brooks, Luis

2015-11-01

Fault detection for automotive semi-active shock absorbers is a challenge due to the non-linear dynamics and the strong influence of the disturbances such as the road profile. First obstacle for this task, is the modeling of the fault, which has been shown to be of multiplicative nature. Many of the most widespread fault detection schemes consider additive faults. Two model-based fault algorithms for semiactive shock absorber are compared: an observer-based approach and a parameter identification approach. The performance of these schemes is validated and compared using a commercial vehicle model that was experimentally validated. Early results shows that a parameter identification approach is more accurate, whereas an observer-based approach is less sensible to parametric uncertainty.

Use of Wedge Absorbers in MICE

Energy Technology Data Exchange (ETDEWEB)

Neuffer, D. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Summers, D. [Univ. of Mississippi, Oxford, MS (United States); Mohayai, T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); IIT, Chicago, IL (United States); Snopok, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); IIT, Chicago, IL (United States); Rogers, C. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL)

2017-03-01

Wedge absorbers are needed to obtain longitudinal cooling in ionization cooling. They also can be used to obtain emittance exchanges between longitudinal and transverse phase space. There can be large exchanges in emittance, even with single wedges. In the present note we explore the use of wedge absorbers in the MICE experiment to obtain transverse–longitudinal emittance exchanges within present and future operational conditions. The same wedge can be used to explore “direct” and “reverse” emittance exchange dynamics, where direct indicates a configuration that reduces momentum spread and reverse is a configuration that increases momentum spread. Analytical estimated and ICOOL and G4BeamLine simulations of the exchanges at MICE parameters are presented. Large exchanges can be obtained in both reverse and direct configurations.

Fluid-driven origami-inspired artificial muscles

Science.gov (United States)

Li, Shuguang; Vogt, Daniel M.; Rus, Daniela; Wood, Robert J.

2017-12-01

Artificial muscles hold promise for safe and powerful actuation for myriad common machines and robots. However, the design, fabrication, and implementation of artificial muscles are often limited by their material costs, operating principle, scalability, and single-degree-of-freedom contractile actuation motions. Here we propose an architecture for fluid-driven origami-inspired artificial muscles. This concept requires only a compressible skeleton, a flexible skin, and a fluid medium. A mechanical model is developed to explain the interaction of the three components. A fabrication method is introduced to rapidly manufacture low-cost artificial muscles using various materials and at multiple scales. The artificial muscles can be programed to achieve multiaxial motions including contraction, bending, and torsion. These motions can be aggregated into systems with multiple degrees of freedom, which are able to produce controllable motions at different rates. Our artificial muscles can be driven by fluids at negative pressures (relative to ambient). This feature makes actuation safer than most other fluidic artificial muscles that operate with positive pressures. Experiments reveal that these muscles can contract over 90% of their initial lengths, generate stresses of ˜600 kPa, and produce peak power densities over 2 kW/kg—all equal to, or in excess of, natural muscle. This architecture for artificial muscles opens the door to rapid design and low-cost fabrication of actuation systems for numerous applications at multiple scales, ranging from miniature medical devices to wearable robotic exoskeletons to large deployable structures for space exploration.

Effects of Burnable Absorbers on PWR Spent Nuclear Fuel

International Nuclear Information System (INIS)

O'Leary, P.M.; Pitts, M.L.

2000-01-01

Burnup credit is an ongoing issue in designing and licensing transportation and storage casks for spent nuclear fuel (SNF). To address this issue, in July 1999, the U.S. Nuclear Regulatory Commission (NRC), Spent Fuel Project Office, issued Interim Staff Guidance-8 (ISG-8), Revision 1 allowing limited burnup credit for pressurized water reactor (PWR) spent nuclear fuel (SNF) to be used in transport and storage casks. However, one of the key limitations for a licensing basis analysis as stipulated in ISG-8, Revision 1 is that ''burnup credit is restricted to intact fuel assemblies that have not used burnable absorbers''. Because many PWR fuel designs have incorporated burnable-absorber rods for more than twenty years, this restriction places an unnecessary burden on the commercial nuclear power industry. This paper summarizes the effects of in-reactor irradiation on the isotopic inventory of PWR fuels containing different types of integral burnable absorbers (BAs). The work presented is illustrative and intended to represent typical magnitudes of the reactivity effects from depleting PWR fuel with different types of burnable absorbers

Parametrization of complex absorbing potentials for time-dependent quantum dynamics

International Nuclear Information System (INIS)

Vibok, A.; Balint-Kurti, G.G.

1992-01-01

Five different forms of complex absorbing potentials are examined and compared. Such potentials are needed to absorb wavepackets near the edges of grids in time-dependent quantum dynamical calculations. The extent to which the different potentials transmit or reflect an incident wavepacket is quantified, and optimal potential parameters to minimize both the reflection and transmission for each type of potential are derived. A rigorously derived scaling procedure, which permits the derivation of optimal potential parameters for use with any chosen mass or kinetic energy from those optimized for different conditions, is described. Tables are also presented which permit the immediate selection of the parameters for an absorbing potential of a particular form so as to allow a preselected (very small) degree of transmitted plus reflected probability to be attained. It is always desirable to devote a minimal region to the absorbing potential, while at the same time effectively absorbing all of the wavepacket and neither transmitting nor reflecting any of it. The tables presented here enable the use to easily select the potential parameters he will require to attain these goals. 23 refs., 7 figs., 4 tabs

Study on 'Tannix' an absorbent for heavy metals including uranium

International Nuclear Information System (INIS)

Nakamura, Yasuo

1997-01-01

To treat radioactive wastes including uranium and transuranic elements such as plutonium, americium etc., development of an absorbent which can be used to absorb and isolate these elements without producing secondary wastes after treatment was attempted. And an absorbent has been successfully developed by polymerizing tannin, a natural product. It is known that tannin binds heavy metals including uranium resulting to produce their precipitates. There are some reports suggesting its absorption ability for uranium. However, tannin has not been used to isolate a heavy metal from a solution because it is soluble in water. Here, insolubilization of tannin was attempted and a manufacturing method for a gelatinized insoluble tannin named as ''Tannix'' was established. Wattle tannin extracted from Mimosa pudica produced in Africa was dissolved in an alkaline solution and gelatinized by heating after the addition of formalin. Thus obtained insoluble tannin was used after crushing and sieving. This product, ''Tannix'' was able to absorb more than 99% of uranium in the waste. And the absorbed Tannin could be degraded by incineration even at a low temperature, leaving only uranium, but not producing any secondary product. (M.N.)

Study on `Tannix` an absorbent for heavy metals including uranium

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Yasuo [Mitsubishi Nuclear Fuel Co. Ltd., Tokyo (Japan)

1997-09-01

To treat radioactive wastes including uranium and transuranic elements such as plutonium, americium etc., development of an absorbent which can be used to absorb and isolate these elements without producing secondary wastes after treatment was attempted. And an absorbent has been successfully developed by polymerizing tannin, a natural product. It is known that tannin binds heavy metals including uranium resulting to produce their precipitates. There are some reports suggesting its absorption ability for uranium. However, tannin has not been used to isolate a heavy metal from a solution because it is soluble in water. Here, insolubilization of tannin was attempted and a manufacturing method for a gelatinized insoluble tannin named as ``Tannix`` was established. Wattle tannin extracted from Mimosa pudica produced in Africa was dissolved in an alkaline solution and gelatinized by heating after the addition of formalin. Thus obtained insoluble tannin was used after crushing and sieving. This product, ``Tannix`` was able to absorb more than 99% of uranium in the waste. And the absorbed Tannin could be degraded by incineration even at a low temperature, leaving only uranium, but not producing any secondary product. (M.N.)

Resonant passive–active vibration absorber with integrated force feedback control

International Nuclear Information System (INIS)

Høgsberg, Jan; Brodersen, Mark L; Krenk, Steen

2016-01-01

A general format of a two-terminal vibration absorber is constructed by placing a passive unit in series with a hybrid unit, composed of an active actuator in parallel with a second passive element. The displacement of the active actuator is controlled by an integrated feedback control with the difference in force between the two passive elements as input. This format allows passive and active contributions to be combined arbitrarily within the hybrid unit, which results in a versatile absorber format with guaranteed closed-loop stability. This is demonstrated for resonant absorbers with inertia realized passively by a mechanical inerter or actively by the integrated force feedback. Accurate calibration formulae are presented for two particular absorber configurations and the performance is subsequently demonstrated with respect to both equal modal damping and effective response reduction. (technical note)

Broadband infrared metamaterial absorber based on anodic aluminum oxide template

Science.gov (United States)

Yang, Jingfan; Qu, Shaobo; Ma, Hua; Wang, Jiafu; Yang, Shen; Pang, Yongqiang

2018-05-01

In this work, a broadband infrared metamaterial absorber is proposed based on trapezoid-shaped anodic aluminum oxide (AAO) template. Unlike traditional metamaterial absorber constructed from metal-dielectric-metal sandwich structure, our proposed absorber is composed of trapezoid-shaped AAO template with metallic nanowires inside. The infrared absorption efficiency is numerically calculated and the mechanism analysis is given in the paper. Owing to the superposition of multiple resonances produced by the nanowires with different heights, the infrared metamatrial absorber can keep high absorption efficiency during broad working wavelength band from 3.4 μm to 6.1 μm. In addition, the resonance wavelength is associated with the height of nanowires, which indicates that the resonance wavelength can be modulated flexibly through changing the heights of nanowires. This kind of design can also be adapted to other wavelength regions.

A review on the performance of conventional and energy-absorbing rockbolts

Directory of Open Access Journals (Sweden)

Charlie C. Li

2014-08-01

Full Text Available This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load–displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.

The MIRD method of estimating absorbed dose

International Nuclear Information System (INIS)

Weber, D.A.

1991-01-01

The estimate of absorbed radiation dose from internal emitters provides the information required to assess the radiation risk associated with the administration of radiopharmaceuticals for medical applications. The MIRD (Medical Internal Radiation Dose) system of dose calculation provides a systematic approach to combining the biologic distribution data and clearance data of radiopharmaceuticals and the physical properties of radionuclides to obtain dose estimates. This tutorial presents a review of the MIRD schema, the derivation of the equations used to calculate absorbed dose, and shows how the MIRD schema can be applied to estimate dose from radiopharmaceuticals used in nuclear medicine

Optimization of Perfect Absorbers with Multilayer Structures

Science.gov (United States)

Li Voti, Roberto

2018-02-01

We study wide-angle and broadband perfect absorbers with compact multilayer structures made of a sequence of ITO and TiN layers deposited onto a silver thick layer. An optimization procedure is introduced for searching the optimal thicknesses of the layers so as to design a perfect broadband absorber from 400 nm to 750 nm, for a wide range of angles of incidence from 0{°} to 50{°}, for both polarizations and with a low emissivity in the mid-infrared. We eventually compare the performances of several optimal structures that can be very promising for solar thermal energy harvesting and collectors.

Device for absorbing seismic effects on buildings

International Nuclear Information System (INIS)

Xercavins, Pierre; Pompei, Michel.

1979-01-01

Device for absorbing seismic effects. The construction or structure to be protected rests on its foundations through at least one footing formed of a stack of metal plates interlinked by layers of adhesive material, over at least a part of their extent, this material being an elastomer that can distort, characterized in that at least part of the area of some metal plates works in association with components which are able to absorb at least some of the energy resulting from friction during the relative movements of the metal plates against the distortion of the elastomer [fr

Graphene Based Terahertz Absorber Designed With Effective Surface Conductivity Approach

DEFF Research Database (Denmark)

Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

Young field of terahertz (THz) science and technology demands new materials and devices, such as filters, modulators, polarization converters and absorbers. Graphene, a recently discovered single-atom-thick material, provides exciting properties for functional terahertz applications. Graphene...... conductivity and how to use it in optical design. We demonstrate a tunable THz perfect absorber, which consists of continuous graphene various structured graphene metamaterials above a metal mirror. Changing the Fermi level from 0 eV to 0.5 eV allows for drastic changes in absorbance from less than 0.1 to 1...

Applying an overstress principle in accelerated testing of absorbing mechanisms

Science.gov (United States)

Tsyss, V. G.; Sergaeva, M. Yu; Sergaev, A. A.

2018-04-01

The relevance of using overstress test as a forced one to determine the pneumatic absorber lifespan was studied. The obtained results demonstrated that at low load overstress the relative error for the absorber lifespan evaluation is no more than 3%. This means that the test results spread has almost no effect on the lifespan evaluation, and this effect is several times less than that at high load overstress tests. Accelerated testing of absorbers with low load overstress is more acceptable since the relative error for the lifespan evaluation is negligible.

Neutron physics calculation for WWER-1000 absorber element lifetime determination

International Nuclear Information System (INIS)

Kurakin, K.Yu.; Kushmanov, S.A.

2009-01-01

Absorber element with compound absorber has been operating in WWER-1000 power units since 1995. AE design meets operating organizations requirements for reliability, service life (to 10 years) and safety functions. Extension of AE service life up to 20 - 30 years by the complex of calculation and experimental work is an important problem of WWER new designs development. The paper deals with the issues related to calculation determination of main factors that influence AE service life limitation - neutron flux and fluence onto absorbing and structural materials during extended service life. (Authors)

Local synaptic signaling enhances the stochastic transport of motor-driven cargo in neurons

KAUST Repository

Newby, Jay

2010-08-23

The tug-of-war model of motor-driven cargo transport is formulated as an intermittent trapping process. An immobile trap, representing the cellular machinery that sequesters a motor-driven cargo for eventual use, is located somewhere within a microtubule track. A particle representing a motor-driven cargo that moves randomly with a forward bias is introduced at the beginning of the track. The particle switches randomly between a fast moving phase and a slow moving phase. When in the slow moving phase, the particle can be captured by the trap. To account for the possibility that the particle avoids the trap, an absorbing boundary is placed at the end of the track. Two local signaling mechanisms-intended to improve the chances of capturing the target-are considered by allowing the trap to affect the tug-of-war parameters within a small region around itself. The first is based on a localized adenosine triphosphate (ATP) concentration gradient surrounding a synapse, and the second is based on a concentration of tau-a microtubule-associated protein involved in Alzheimer\\'s disease-coating the microtubule near the synapse. It is shown that both mechanisms can lead to dramatic improvements in the capture probability, with a minimal increase in the mean capture time. The analysis also shows that tau can cause a cargo to undergo random oscillations, which could explain some experimental observations. © 2010 IOP Publishing Ltd.

The Development of 6061-Aluminum Windows for the MICE Liquid Absorber

International Nuclear Information System (INIS)

Lau, W.; Yang, S.Q.; Green, M.A.; Ishimoto, S.; Swanson, J.

2005-01-01

The thin windows for the Muon Ionization Cooling Experiment (MICE) liquid Absorber will be fabricated from 6061-T6-aluminum. The absorber and vacuum vessel thin windows are 300-mm in diameter and are 180 mm thick at the center. The windows are designed for an internal burst pressure of 0.68 MPa (100 psig) when warm. The MICE experiment design calls for changeable windows on the absorber, so a bolted window design was adopted. Welded windows offer some potential advantages over bolted windows when they are on the absorber itself. This report describes the bolted window and its seal. This report also describes an alternate window that is welded directly to the absorber body. The welded window design presented permits the weld to be ground off and re-welded. This report presents a thermal FEA analysis of the window seal-weld, while the window is being welded. Finally, the results of a test of a welded-window are presented

A Comprehensive Review of the Techniques on Regenerative Shock Absorber Systems

Directory of Open Access Journals (Sweden)

Ran Zhang

2018-05-01

Full Text Available In this paper, the current technologies of the regenerative shock absorber systems have been categorized and evaluated. Three drive modes of the regenerative shock absorber systems, namely the direct drive mode, the indirect drive mode and hybrid drive mode are reviewed for their readiness to be implemented. The damping performances of the three different modes are listed and compared. Electrical circuit and control algorithms have also been evaluated to maximize the power output and to deliver the premium ride comfort and handling performance. Different types of parameterized road excitations have been applied to vehicle suspension systems to investigate the performance of the regenerative shock absorbers. The potential of incorporating nonlinearity into the regenerative shock absorber design analysis is discussed. The research gaps for the comparison of the different drive modes and the nonlinearity analysis of the regenerative shock absorbers are identified and, the corresponding research questions have been proposed for future work.

Design of a five-band terahertz perfect metamaterial absorber using two resonators

Science.gov (United States)

Meng, Tianhua; Hu, Dan; Zhu, Qiaofen

2018-05-01

We present a polarization-insensitive five-band terahertz perfect metamaterial absorber composed of two metallic circular rings and a metallic ground film separated by a dielectric layer. The calculated results show that the absorber has five distinctive absorption bands whose peaks are greater than 99% on average. The physical origin of the absorber originates from the combination of dipolar, hexapolar, and surface plasmon resonance of the patterned metallic structure, which is different from the work mechanism of previously reported absorbers. In addition, the influence of the structural parameters on the absorption spectra is analyzed to further confirm the origin of the five-band absorption peaks. The proposed absorber has potential applications in terahertz imaging, refractive index sensing, and material detecting.

A checkerboard selective absorber with excellent spectral selectivity

Energy Technology Data Exchange (ETDEWEB)

Yang, Liu, E-mail: optyang@zju.edu.cn [Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058 (China); School of Electrical, Computer, and Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Mo, Lei; Chen, Tuo [Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058 (China); Department of Physics, Zhejiang University, Hangzhou 310027 (China); Forsberg, Erik [Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058 (China); He, Sailing [Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058 (China); Department of Electromagnetic Engineering, JORCEP, Roy Institute of Technology (KTH), S-100 44 Stockholm (Sweden)

2015-11-14

A selective absorber with excellent spectral selectivity is proposed and analyzed. The absorber is based on a germanium (Ge) checkerboard on top of a tantalum (Ta) substrate. At wavelengths shorter than the 1.2 μm cutoff, a very high absorption is achieved due to strong cavity resonances in the Ge nanosquares, and their interactions with adjacent nanocavities and the bottom Ta substrate. At longer wavelengths, absorption is greatly suppressed due to destructive interference between the transparent checkerboard layer and the highly reflective Ta substrate. To better describe the superior selectivity of our configuration, a new figure of merit (FOM) is introduced. We observe a FOM value of 0.88 compared to 0.69 for its planar counterpart. We also conduct a thermal analysis to verify the excellent selectivity of our absorber. A high temperature can be achieved and maintained, promising good potential for applications in solar thermophotovoltaic systems.

Cross connecting absorber module inlets of multiple boiler units

International Nuclear Information System (INIS)

Cirillo, A.J.; Sperber, P.K.; Belavadi, V.N.; Mukherji, A.

1991-01-01

The retrofitting of scrubbers downstream of existing balanced draft boilers is often accomplished by the addition of induced draft (ID) booster fans. By creating a common plenum between the ID fans and the ID booster fans of two or more boiler-absorber trains, absorber module capacity may be shared among multiple boiler units. At Harrison Power Station, three (3) 4,900,000 lb/hour boilers (640 MWe Gross) will be linked through a common plenum. This sharing capability precludes the need to add standby module capacity, thereby saving capital dollars and keeping project critical path schedules, which typically run through absorber procurement and construction, to a minimum. Through damper placement in the ductwork cross connections, unitized boiler-absorber module operation or common plenum operation may be obtained, thus providing both operational flexibility and reliability. Additionally, open plenum operation allows the removal of an absorber unit from service, while keeping its associated boiler on line, thereby precluding 'cold starts' and maintaining overall unit availabilities. As either unitized or common plenum operation is possible with the cross connection, the furnace draft control systems of each boiler must be examined for varying load operation and trip conditions. This paper addresses the means by which to analyze such cross connection operational scenarios while maintaining compliance with furnace flame out safety guidelines, and will discuss the physical design considerations, ramifications and benefits of same, with select emphasis on what is being implemented at the Harrison Power Station

Robust optimization of a tandem grating solar thermal absorber

Science.gov (United States)

Choi, Jongin; Kim, Mingeon; Kang, Kyeonghwan; Lee, Ikjin; Lee, Bong Jae

2018-04-01

Ideal solar thermal absorbers need to have a high value of the spectral absorptance in the broad solar spectrum to utilize the solar radiation effectively. Majority of recent studies about solar thermal absorbers focus on achieving nearly perfect absorption using nanostructures, whose characteristic dimension is smaller than the wavelength of sunlight. However, precise fabrication of such nanostructures is not easy in reality; that is, unavoidable errors always occur to some extent in the dimension of fabricated nanostructures, causing an undesirable deviation of the absorption performance between the designed structure and the actually fabricated one. In order to minimize the variation in the solar absorptance due to the fabrication error, the robust optimization can be performed during the design process. However, the optimization of solar thermal absorber considering all design variables often requires tremendous computational costs to find an optimum combination of design variables with the robustness as well as the high performance. To achieve this goal, we apply the robust optimization using the Kriging method and the genetic algorithm for designing a tandem grating solar absorber. By constructing a surrogate model through the Kriging method, computational cost can be substantially reduced because exact calculation of the performance for every combination of variables is not necessary. Using the surrogate model and the genetic algorithm, we successfully design an effective solar thermal absorber exhibiting a low-level of performance degradation due to the fabrication uncertainty of design variables.

Heaving buoys, point absorbers and arrays.

Science.gov (United States)

Falnes, Johannes; Hals, Jørgen

2012-01-28

Absorption of wave energy may be considered as a phenomenon of interference between incident and radiated waves generated by an oscillating object; a wave-energy converter (WEC) that displaces water. If a WEC is very small in comparison with one wavelength, it is classified as a point absorber (PA); otherwise, as a 'quasi-point absorber'. The latter may be a dipole-mode radiator, for instance an immersed body oscillating in the surge mode or pitch mode, while a PA is so small that it should preferably be a source-mode radiator, for instance a heaving semi-submerged buoy. The power take-off capacity, the WEC's maximum swept volume and preferably also its full physical volume should be reasonably matched to the wave climate. To discuss this matter, two different upper bounds for absorbed power are applied in a 'Budal diagram'. It appears that, for a single WEC unit, a power capacity of only about 0.3 MW matches well to a typical offshore wave climate, and the full physical volume has, unfortunately, to be significantly larger than the swept volume, unless phase control is used. An example of a phase-controlled PA is presented. For a sizeable wave-power plant, an array consisting of hundreds, or even thousands, of mass-produced WEC units is required.

Performance Comparison of Mode-Locked Erbium-Doped Fiber Laser with Nonlinear Polarization Rotation and Saturable Absorber Approaches

International Nuclear Information System (INIS)

Ismail, M. A.; Tan, S. J.; Shahabuddin, N. S.; Harun, S. W.; Arof, H.; Ahmad, H.

2012-01-01

A mode-locked erbium-doped fiber laser (EDFL) is demonstrated using a highly concentrated erbium-doped fiber (EDF) as the gain medium in a ring configuration with and without a saturable absorber (SA). Without the SA, the proposed laser generates soliton pulses with a repetition rate of 12 MHz, pulse width of 1.11 ps and energy pulse of 1.6 pJ. By incorporating SA in the ring cavity, the optical output of the laser changes from soliton to stretched pulses due to the slight change in the group velocity dispersion. With the SA, a cleaner pulse is obtained with a repetition rate of 11.3 MHz, a pulse width of 0.58 ps and a pulse energy of 2.3 pJ. (fundamental areas of phenomenology(including applications))

Multi-Speed Transmission For Commercial Delivery Medium Duty PEDVs

Energy Technology Data Exchange (ETDEWEB)

Chavdar, Bulent [Eaton Corp., Menomonee Falls, WI (United States)

2017-12-31

Successful completion of the proposed project will set a course for improving quality of life by overcoming key challenges in the gearbox for commercial-delivery, medium-duty, plug-in electric drive vehicles: It will reduce US dependency on foreign oil through the use of electric driven propulsion instead of fuel driven. It will reduce health risks by replacing tailpipe emissions in densely populated city centers. Finally, it will improve the performance-cost basis to meet or exceed the expectations of the targeted medium duty vehicle fleet owners and the independent customers. The proposed multi-speed transmission will narrow motor operation to the peak efficiency region, thereby increasing the electric powertrain efficiency to help close the range gap. Further, it will enhance customer satisfaction by improving vehicle acceleration, top speed and gradeability over the baseline. The project was conducted in three budget periods: In BP1: Technology Development, High-level vehicle powertrain models were used to optimize candidate transmission architectures and ratios along with a variety of traction motor characteristics for concept selection. The detailed driveline designs and component dynamics were investigated to meet medium-duty EV requirements; In BP2: Technology Development and Prototype Demonstration, The modeling and simulations with multi-speed transmissions were extended to other MD and HD EV platforms. Clean sheet design of a compact, lightweight, flexible, and modular, four-speed transmission was completed. Development of novel shifting and controls strategies were started and procurement of the prototype transmission and the controller hardware was begun; In BP3: Technology Integration, Testing, and Demonstration, Prototyping the four-speed automated mechanical transmission was completed. The transmission controls system and software development and preliminary gearbox dyno tests were done at Eaton. ORNL conducted integrated powertrain HIL tests. One

Writable and erasable PPV medium by irradiation at 365 nm

Energy Technology Data Exchange (ETDEWEB)

Mochizuki, Hiroyuki [Photonics Research Institutes, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)], E-mail: h-mochizuki@aist.go.jp; Mizokuro, Toshiko; Tanigaki, Nobutaka; Hiraga, Takashi [Photonics Research Institutes, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

2008-03-03

Dopings of vaporized cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl) ethane (CMTE) into poly(methyl methacrylate) (PMMA), polystyrene, and polycarbonate were performed by a vacuum process, and the doping behaviors of CMTE were evaluated. Among the matrix polymers, PMMA was dispersed CMTE densely in its surface region. By using the CMTE-doped PMMA, we could fabricate a novel rewritable medium: a multi-layered film was prepared from over-coating of CMTE-doped PMMA onto poly(p-phenylene vinylene) (PPV) film, which set on a transparent substrate. Image storage could be performed upon irradiation at 365 nm at the side of CMTE/PMMA layer: color of the irradiated area changed a light yellow to a red due to photo-isomerization of CMTE. Next, upon irradiation at 365 nm at the side of the transparent substrate, PPV emitted a green fluorescence at around 530 nm, and the CMTE absorbed the emission from PPV causing image-erasure based on back-isomerization of CMTE.

A study of the effect on human mesenchymal stem cells of an atmospheric pressure plasma source driven by different voltage waveforms

Science.gov (United States)

Laurita, R.; Alviano, F.; Marchionni, C.; Abruzzo, P. M.; Bolotta, A.; Bonsi, L.; Colombo, V.; Gherardi, M.; Liguori, A.; Ricci, F.; Rossi, M.; Stancampiano, A.; Tazzari, P. L.; Marini, M.

2016-09-01

The effect of an atmospheric pressure non-equilibrium plasma on human mesenchymal stem cells was investigated. A dielectric barrier discharge non-equilibrium plasma source driven by two different high-voltage pulsed generators was used and cell survival, senescence, proliferation, and differentiation were evaluated. Cells deprived of the culture medium and treated with nanosecond pulsed plasma showed a higher mortality rate, while higher survival and retention of proliferation were observed in cells treated with microsecond pulsed plasma in the presence of the culture medium. While a few treated cells showed the hallmarks of senescence, unexpected delayed apoptosis ensued in cells exposed to plasma-treated medium. The plasma treatment did not change the expression of OCT4, a marker of mesenchymal stem cell differentiation.

Absorbable and biodegradable polymers

CERN Document Server

Shalaby, Shalaby W

2003-01-01

INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

THE MORPHOLOGY AND DYNAMICS OF JET-DRIVEN SUPERNOVA REMNANTS: THE CASE OF W49B

Energy Technology Data Exchange (ETDEWEB)

González-Casanova, Diego F.; De Colle, Fabio [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A. P. 70-543, 04510 D. F. (Mexico); Ramirez-Ruiz, Enrico [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Lopez, Laura A. [MIT-Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-664H, Cambridge, MA 02139 (United States)

2014-02-01

The circumstellar medium (CSM) of a massive star is modified by its winds before a supernova (SN) explosion occurs, and thus the evolution of the resulting supernova remnant (SNR) is influenced by both the geometry of the explosion as well as the complex structure of the CSM. Motivated by recent work suggesting the SNR W49B was a jet-driven SN expanding in a complex CSM, we explore how the dynamics and the metal distributions in a jet-driven explosion are modified by the interaction with the surrounding environment. In particular, we perform hydrodynamical calculations to study the dynamics and explosive nucleosynthesis of a jet-driven SN triggered by the collapse of a 25 M {sub ☉} Wolf-Rayet star and its subsequent interaction with the CSM up to several hundred years following the explosion. We find that although the CSM has small-scale effects on the structure of the SNR, the overall morphology and abundance patterns are reflective of the initial asymmetry of the SN explosion. Thus, we predict that jet-driven SNRs, such as W49B, should be identifiable based on morphology and abundance patterns at ages up to several hundred years, even if they expand into a complex CSM environment.

Micropropagation of Alstroemeria in liquid medium using slow release of medium components

NARCIS (Netherlands)

Klerk, de G.J.M.; Brugge, ter J.

2010-01-01

Alstroemeria rhizomes were micropropagated on semi-solid medium (AM) and in liquid medium (LM). In LM, growth was much enhanced (ca. 70%). Adequate gas exchange was crucial. This was obtained by agitation and in static medium by a sufficient large contact area of the explant and the gaseous

Dual-band absorber for multispectral plasmon-enhanced infrared photodetection

International Nuclear Information System (INIS)

Yu, Peng; Ashalley, Eric; Wang, Zhiming; Wu, Jiang; Govorov, Alexander

2016-01-01

For most of the reported metamaterial absorbers, the peak absorption only occurs at one single wavelength. Here, we investigated a dual-band absorber which is based on simple gold nano-rings. Two absorption peaks can be readily achieved in 3–5 µ m and 8–14 µ m via tuning the width and radius of gold nano-rings and dielectric constant. The average maximum absorption of two bands can be as high as 95.1% (−0.22 dB). Based on the simulation results, the perfect absorber with nano-rings demonstrates great flexibility to create dual-band or triple-band absorption, and thus holds potential for further applications in thermophotovoltaics, multicolor infrared focal plane arrays, optical filters, and biological sensing applications. (paper)

Development of an innovative solar absorber

Science.gov (United States)

Goodchild, Gavin

Solar thermal systems have great potential to replace or reduce the dependence of conventional fossil fuel based heating technologies required for space and water heating. Specifically solar domestic hot water systems can contribute 50-75% of the annual thermal load. To date residential users have been slow to purchase and install systems, primarily due to the large monetary investment required to purchase and install a system. Recent innovations in materials design and manufacturing techniques, offer opportunities for the development of absorber plate designs that have the potential to reduce cost, increase efficiency and reduce payback periods. Consequently, this design study was conducted in conjunction with industrial partners to develop an improved absorber based on roll bond manufacturing that can be produced at reduced cost with comparable or greater thermal efficiency.

Ground-plane-less bidirectional terahertz absorber based on omega resonators

NARCIS (Netherlands)

Balmakou, Alexei; Podalov, Maxim; Khakhomov, Sergei; Stavenga, Doekele; Semchenko, Igor

2015-01-01

We present a new ultrathin metamaterial that acts as a frequency-selective absorber of terahertz radiation. The absorber is a square array of pairs of omega-shaped micro-resonators made of high-ohmic-loss metal. The metamaterial provides significant suppression of transmitted and reflected radiation

RF electromagnetic wave absorbing properties of ferrite polymer composite materials

International Nuclear Information System (INIS)

Dosoudil, Rastislav; Usakova, Marianna; Franek, Jaroslav; Slama, Jozef; Olah, Vladimir

2006-01-01

The frequency dispersion of complex initial (relative) permeability (μ * =μ ' -jμ ' ') and the electromagnetic wave absorbing properties of composite materials based on NiZn sintered ferrite and a polyvinylchloride (PVC) polymer matrix have been studied in frequency range from 1MHz to 1GHz. The complex permeability of the composites was found to increase as the ferrite content increased, and was characterized by frequency dispersion localized above 50MHz. The variation of return loss (RL) of single-layer RF absorbers using the prepared composite materials has been investigated as a function of frequency, ferrite content and the thickness of the absorbers

Broadband polarization-independent and low-profile optically transparent metamaterial absorber

Science.gov (United States)

Li, Long; Xi, Rui; Liu, Haixia; Lv, Zhiyong

2018-05-01

A transparent metamaterial absorber with simultaneously high optical transparency and broadband microwave absorption is presented in this paper. Consisting of a two-layer soda-lime glass substrate and three-layer patch-shaped indium tin oxide (ITO) films, the proposed absorber has advantages of broadband absorption with an absorptivity higher than 85% in the range from 6.1 to 22.1 GHz, good polarization insensitiveness, a high transparency, a low profile, and wide-incident-angle stability. A prototype of the proposed absorber is fabricated and experimentally measured to demonstrate its excellent performance. The measured results agree well with the theoretical design and numerical simulations.

An absorbed dose calorimeter for IMRT dosimetry

International Nuclear Information System (INIS)

Duane, S.; Aldehaybes, M.; Bailey, M.; Lee, N.D.; Thomas, C.G.; Palmans, H.

2012-01-01

A new calorimeter for dosimetry in small and complex fields has been built. The device is intended for the direct determination of absorbed dose to water in moderately small fields and in composite fields such as IMRT treatments, and as a transfer instrument calibrated against existing absorbed dose standards in conventional reference conditions. The geometry, materials and mode of operation have been chosen to minimize detector perturbations when used in a water phantom, to give a reasonably isotropic response and to minimize the effects of heat transfer when the calorimeter is used in non-reference conditions in a water phantom. The size of the core is meant to meet the needs of measurement in IMRT treatments and is comparable to the size of the air cavity in a type NE2611 ionization chamber. The calorimeter may also be used for small field dosimetry. Initial measurements in reference conditions and in an IMRT head and neck plan, collapsed to gantry angle zero, have been made to estimate the thermal characteristics of the device, and to assess its performance in use. The standard deviation (estimated repeatability) of the reference absorbed dose measurements was 0.02 Gy (0.6%). (authors)

High-Capacity Spacesuit Evaporator Absorber Radiator (SEAR)

Science.gov (United States)

Izenson, Michael G.; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Quinn, Gregory

2015-01-01

Future human space exploration missions will require advanced life support technology that can operate across a wide range of applications and environments. Thermal control systems for space suits and spacecraft will need to meet critical requirements for water conservation and multifunctional operation. This paper describes a Space Evaporator Absorber Radiator (SEAR) that has been designed to meet performance requirements for future life support systems. A SEAR system comprises a lithium chloride absorber radiator (LCAR) for heat rejection coupled with a space water membrane evaporator (SWME) for heat acquisition. SEAR systems provide heat pumping to minimize radiator size, thermal storage to accommodate variable environmental conditions, and water absorption to minimize use of expendables. We have built and tested a flight-like, high-capacity LCAR, demonstrated its performance in thermal vacuum tests, and explored the feasibility of an ISS demonstration test of a SEAR system. The new LCAR design provides the same cooling capability as prior LCAR prototypes while enabling over 30% more heat absorbing capacity. Studies show that it should be feasible to demonstrate SEAR operation in flight by coupling with an existing EMU on the space station.

Multi-Absorber Transition-Edge Sensors for X-Ray Astronomy Applications

Science.gov (United States)

Smith, S. J.; Adams, J. S.; Bandler, S. R.; Busch, S. E.; Chervenak, J. A.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kelly, D. P.;