WorldWideScience

Sample records for far-field radiation pattern

  1. EM modeling of far-field radiation patterns for antennas on the GMA-TT UAV

    Science.gov (United States)

    Mackenzie, Anne I.

    2015-05-01

    To optimize communication with the Generic Modular Aircraft T-Tail (GMA-TT) unmanned aerial vehicle (UAV), electromagnetic (EM) simulations have been performed to predict the performance of two antenna types on the aircraft. Simulated far-field radiation patterns tell the amount of power radiated by the antennas and the aircraft together, taking into account blockage by the aircraft as well as radiation by conducting and dielectric portions of the aircraft. With a knowledge of the polarization and distance of the two communicating antennas, e.g. one on the UAV and one on the ground, and the transmitted signal strength, a calculation may be performed to find the strength of the signal travelling from one antenna to the other and to check that the transmitted signal meets the receiver system requirements for the designated range. In order to do this, the antenna frequency and polarization must be known for each antenna, in addition to its design and location. The permittivity, permeability, and geometry of the UAV components must also be known. The full-wave method of moments solution produces the appropriate dBi radiation pattern in which the received signal strength is calculated relative to that of an isotropic radiator.

  2. EM Modeling of Far-Field Radiation Patterns for Antennas on the GMA-TT UAV

    Science.gov (United States)

    Mackenzie, Anne I.

    2015-01-01

    To optimize communication with the Generic Modular Aircraft T-Tail (GMA-TT) unmanned aerial vehicle (UAV), electromagnetic (EM) simulations have been performed to predict the performance of two antenna types on the aircraft. Simulated far-field radiation patterns tell the amount of power radiated by the antennas and the aircraft together, taking into account blockage by the aircraft as well as radiation by conducting and dielectric portions of the aircraft. With a knowledge of the polarization and distance of the two communicating antennas, e.g. one on the UAV and one on the ground, and the transmitted signal strength, a calculation may be performed to find the strength of the signal travelling from one antenna to the other and to check that the transmitted signal meets the receiver system requirements for the designated range. In order to do this, the antenna frequency and polarization must be known for each antenna, in addition to its design and location. The permittivity, permeability, and geometry of the UAV components must also be known. The full-wave method of moments solution produces the appropriate dBi radiation pattern in which the received signal strength is calculated relative to that of an isotropic radiator.

  3. Topological magnetoelectric effects in microwave far-field radiation

    Energy Technology Data Exchange (ETDEWEB)

    Berezin, M.; Kamenetskii, E. O.; Shavit, R. [Microwave Magnetic Laboratory, Department of Electrical and Computer Engineering, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2016-07-21

    Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME-coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently, it was shown that the near fields in the proximity of a small ferrite particle with magnetic-dipolar-mode (MDM) oscillations have the space and time symmetry breakings and the topological properties of these fields are different from the topological properties of the free-space electromagnetic fields. Such MDM-originated fields—called magnetoelectric (ME) fields—carry both spin and orbital angular momenta. They are characterized by power-flow vortices and non-zero helicity. In this paper, we report on observation of the topological ME effects in far-field microwave radiation based on a small microwave antenna with a MDM ferrite resonator. We show that the microwave far-field radiation can be manifested with a torsion structure where an angle between the electric and magnetic field vectors varies. We discuss the question on observation of the regions of localized ME energy in far-field microwave radiation.

  4. Efficient Compression of Far Field Matrices in Multipole Algorithms based on Spherical Harmonics and Radiating Modes

    Directory of Open Access Journals (Sweden)

    A. Schroeder

    2012-09-01

    Full Text Available This paper proposes a compression of far field matrices in the fast multipole method and its multilevel extension for electromagnetic problems. The compression is based on a spherical harmonic representation of radiation patterns in conjunction with a radiating mode expression of the surface current. The method is applied to study near field effects and the far field of an antenna placed on a ship surface. Furthermore, the electromagnetic scattering of an electrically large plate is investigated. It is demonstrated, that the proposed technique leads to a significant memory saving, making multipole algorithms even more efficient without compromising the accuracy.

  5. Topological magnetoelectric effects in microwave far-field radiation

    CERN Document Server

    Berezin, M; Shavit, R

    2015-01-01

    Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently it was shown that the near fields in the proximity of a small ferrite particle with magnetic dipolar mode (MDM) oscillations have the space and time symmetry breakings and topological properties of these fields are different from topological properties of the free space electromagnetic (EM) fields. Such MDM originated fields, called magnetoelectric (ME) fields, carry both spin and orbital angular momentums. They are characterized by power flow vortices and non zero helicity. In this paper, we report on observation of the topological ME effects in far field microwave radiation based ...

  6. Chiral-field microwave antennas (Chiral microwave near fields for far-field radiation)

    CERN Document Server

    Kamenetskii, E O; Shavit, R

    2015-01-01

    In a single-element structure we obtain a radiation pattern with a squint due to chiral microwave near fields originated from a magnetostatic-mode ferrite disk. At the magnetostatic resonances, one has strong subwavelength localization of energy of microwave radiation. Magnetostatic oscillations in a thin ferrite disk are characterized by unique topological properties: the Poynting-vector vortices and the field helicity. The chiral-topology near fields allow obtaining unique phase structure distribution for far-field microwave radiation.

  7. Analysis of Far-Field Radiation from Apertures Using Monte Carlo Integration Technique

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Fakharian

    2014-12-01

    Full Text Available An integration technique based on the use of Monte Carlo Integration (MCI is proposed for the analysis of the electromagnetic radiation from apertures. The technique that can be applied to the calculation of the aperture antenna radiation patterns is the equivalence principle followed by physical optics, which can then be used to compute far-field antenna radiation patterns. However, this technique is often complex mathematically, because it requires integration over the closed surface. This paper presents an extremely simple formulation to calculate the far-fields from some types of aperture radiators by using MCI technique. The accuracy and effectiveness of this technique are demonstrated in three cases of radiation from the apertures and results are compared with the solutions using FE simulation and Gaussian quadrature rules.

  8. Strong far field coherent scattering of ultraviolet radiation by holococcolithophores

    CERN Document Server

    Quintero-Torres, R; Torres, M; Estrada, M; Cros, L

    2007-01-01

    By considering the structure of holococcoliths (calcite plates that cover holococcolithophores, a haploid phase of the coccolithophore life cycle) as a photonic structure, we apply a discrete dipolar approximation to study the light backscattering properties of these algae. We show that some holococcolith structures have the ability to scatter the ultraviolet (UV) radiation. This property may represent an advantage for holococcolithophores possessing it, by allowing them to live higher in the water column than other coccolithophores.

  9. Fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse quasicrystals

    Institute of Scientific and Technical Information of China (English)

    YANG Ming-yang; ZHOU Jun; L Petti; S De Nicola; P Mormile

    2011-01-01

    We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse(2-D TM) structures.The far-field diffraction patterns of the 2-D TM structures can be obtained by the numerical method,and they have a good agreement with the experimental ones.The analysis shows that the fractal characteristics of far-field diffraction patterns for the 2-D TM structures are determined by the inflation rule,which have potential applications in the design of optical diffraction devices.

  10. Far-Field Emission Pattern of a Dielectric Circular Microresonator with a Point Scatterer

    NARCIS (Netherlands)

    Dettmann, C.P.; Morozov, G.V.; Sieber, M.; Waalkens, H.

    2008-01-01

    The far-field emission pattern of a two-dimensional circular microresonator with a point scatterer inside, at some distance away from the centre, is investigated theoretically. We demonstrate that the presence of the scatterer leads to significant enhancement in the directionality of the outgoing li

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

    Science.gov (United States)

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

    2016-04-04

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

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

    CERN Document Server

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

    2016-01-01

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

  13. An Analysis of the Far-Field Radiation Pattern of the Ultraviolet Light-Emitting Diode (LED) Engin LZ4-00UA00 Diode with and without Beam Shaping Optics

    Science.gov (United States)

    2015-09-01

    5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Karl K Klett Jr 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7...light-emitting diode (LED), with and without beam shaping optics. This LED has 4 emitters arranged in a square pattern that are off-center from the...in this work that the spectra of the LED, the Lexan LS2 polycarbonate, and the ThorLabs FES0450, 450-nm shortpass filter are correct, as specified in

  14. Numerical analysis of near and far field patterns of second-harmonic generation with tiling nonlinear optical crystals

    Energy Technology Data Exchange (ETDEWEB)

    Harimoto, T [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Kofu, Yamanashi 400-8511 (Japan); Shiraga, H [Institute of Laser Engineering, Osaka University, Suita, Osaka (Japan)], E-mail: harimoto@yamanashi.ac.jp

    2008-05-01

    We report numerical analysis of near- and far-field patterns of the second-harmonic wave in a large-scale high-power laser used in the laser fusion with type I KDP crystals arranged in a tiling style. The thickness and phase-matching angle of the tiling crystals are designed based on the near-field pattern of the second-harmonic wave. The tilting angle error and thickness difference of the tiling crystals are evaluated by the energy distribution included in the Airy spot of the far-field pattern at the focal point. The parallelism and flatness of the tiling crystals can also be estimated with the same method.

  15. Reverse design of a bull's eye structure based on the plasmonic far-field pattern.

    Science.gov (United States)

    Yamada, Akira; Terakawa, Mitsuhiro

    2013-09-09

    We present a novel concept on designing a bull's eye structure for a single-wavelength optical source. The plasmonic far-field around a subwavelength aperture on a thin gold film is calculated by finite-difference time-domain method. Based on the annular field intensity distribution on the film surface, we present a method for determining a fairly optimal first groove radius and a periodicity of the grooves that show enhanced transmission. By additionally fine-tuning groove width and groove depth, we have achieved a transmission factor of 9.74. Our novel method has high potential in applications such as silicon infrared sensors.

  16. Near-to-far field transformations for radiative and guided waves

    CERN Document Server

    Yang, Jianji; Lalanne, Philippe

    2015-01-01

    Light emitters or scatterers embedded in stratified media may couple energy to both free space and guided modes of the stratified structure. For a thorough analysis of such structures, it is important to evaluate the angular intensity distribution of both the free-space-propagative and guided waves. In this work, we propose an original method based on Lorentz-reciprocity theorem and on the computation of the near-field around the emitters or scatterers, to efficiently calculate the free-space and guided radiation diagrams with a high accuracy. We also provide an open-source code that may be used with virtually any Maxwells solver. The numerical tool may help to engineer various devices, such as light-emitting diodes or nanoantennas to achieve directional and efficient radiative spontaneous decays in free space and guided optics.

  17. Far-Field Patterns from Dye-Doped Planar-Aligned Nematic Liquid Crystals Under nanosecond Laser Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Lepeshkin, N.; Boyd, R.W.; Marshall, K.L.

    2006-08-18

    High-definition patterns were observed under 10-Hz-pulse-repetition-rate, nanosecond laser irradiation of azodye-doped planar-nematic liquid crystal layers at incident intensities I ~ 5-10 MW/cm^2 in a single beam configuration and without any feedback involved. An incident polarization parallel to the nematic director was used. Under periodic pulsed laser irradiation, far-field beam patterns at the output of a dye-doped liquid crystal layer changed kaleidoscopically from rings and stripes to multiple hexagons. This pattern-formation regime had a buildup time of several seconds to minutes. We explain the observed effect by diffraction of the laser beam on light-induced micrometer-size inhomogeneities inside the liquid crystal layer with absorption and refraction properties different from the surrounding area. Possible mechanisms of the formation of the inhomogeneities are discussed.

  18. Far field acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Fernow, R.C.

    1995-07-01

    Far fields are propagating electromagnetic waves far from their source, boundary surfaces, and free charges. The general principles governing the acceleration of charged particles by far fields are reviewed. A survey of proposed field configurations is given. The two most important schemes, Inverse Cerenkov acceleration and Inverse free electron laser acceleration, are discussed in detail.

  19. Simultaneous measurement of patterns in the signal and idler near and far fields from a confocal optical parametrical oscillator with applications in quantum optics

    DEFF Research Database (Denmark)

    Lassen, Mikael Østergaard; Tidemand-Lichtenberg, Peter; Buchhave, Preben

    2005-01-01

    investigation of quantum correlations in the transverse plane. We describe the experimental setup for simultaneous measurements of signal and idler near- and far-field patterns and analyze the effects of various experimental complications such as walk-off and thermal index changes on the generated patterns. We...... also show that the oscillator can be stabilized by optical feedback, indicating a possible route for controlling the generated intensity patterns....

  20. Far-field pattern analysis of extended-hemispherical-lens/objective-lens antenna system at millimeter wavelengths

    Science.gov (United States)

    Dou, Wenbin; Sun, Zhong Liang; Zeng, G.

    1998-11-01

    integrated antennas have the advantages of low cost and can be readily mass produced using standard IC fabrication processes. However, integrated antennas suffer from the surface wave effect at millimeter waves. One of the ways to avoid this problem is to integrate the antennas on a dielectric lens. This structure does not support surface-waves and tend to radiate most of their power into the dielectric side making the pattern unidirectional on high dielectric constant lenses. The dielectric lens also provides mechanical rigidity and thermal stability. There are various dielectric lenses which can be used for receiver application. Among them the extended hemispherical lens is very practical, since it can synthesize other lenses such as hemispherical, hyperhemispherical, or ellipsoidal simply by varying the extension length behind the hemispherical position. In reference five, investigation on such antenna/lens system is presented. In reference 6, slot- ring antennas on dielectric lens is investigated. In many applications the extended hemispherical lens/objective lens antenna system is more attractive, because it can provide higher gain and may be used in imaging system. On the other hand, monopulse direction-finding techniques are currently the most accurate and rapid method for locating a target electronically. This antenna system can also be used as monopulse antenna. However, the treatments on such antenna system are not presented yet. In this paper, the radiation pattern of the antenna system fed by double-slot antenna are computed using ray-tracing and diffraction integration methods. Although the double-slot antenna is used as feed antenna, other antenna such as slot-ring, bow-tie antenna can be used too.

  1. Far-Field Pattern Reconstruction from Near-Field Data Collected via a Nonconventional Plane-Rectangular Scanning: Experimental Testing

    Directory of Open Access Journals (Sweden)

    Francesco D’Agostino

    2014-01-01

    Full Text Available This paper deals with the experimental validation of an efficient near-field-far-field (NF-FF transformation using the planar wide-mesh scanning (PWMS. Such a nonconventional plane-rectangular scanning technique is so named, since the sample grid is characterized by meshes wider and wider when going away from the center, and makes it possible to lower the number of needed measurements, as well as the time required for the data acquisition when dealing with quasi-planar antennas. It relies on the use of the nonredundant sampling representations of electromagnetic fields which employ an oblate ellipsoid or a surface formed by two circular “bowls” with the same aperture diameter but eventually different bending radii to shape a quasi-planar antenna. A two-dimensional optimal sampling interpolation formula allows the reconstruction of the NF data at any point on the measurement plane and, in particular, at those required by the classical NF-FF transformation with the conventional plane-rectangular scanning. The measurements, performed at the planar NF facility of the antenna characterization laboratories of Selex ES, have confirmed the effectiveness of this innovative scanning also from the experimental viewpoint.

  2. Notions of support for far fields

    Science.gov (United States)

    Sylvester, John

    2006-08-01

    In practical remote sensing, faraway sources radiate fields that, within measurement precision, are nearly those radiated by point sources. Algorithms like MUSIC (Devaney J. Acoust. Soc. Am. at press, Kirsch 2002 Inverse Problems 18 1025-40) correctly identify their number, their locations and their strengths based on observations of the near or far fields they radiate. Asymptotic perturbation formulae (Ammari et al 2005 SIAM J. Appl. Math. 65 2107-27, Brühl et al 2003 Numer. Math. 93 635-54) have been used to successfully locate small sparse inclusions based on remote measurements. The main motivation for this paper is to locate sources which are supported on sets that are larger and less sparse. Although the far field of a solution to the inhomogeneous Helmholtz equation does not determine the source, or its support, uniquely, we will show how to associate with any far field a unique union of well-separated-convex sets (UWSC sets) that is both big enough to support a source that can radiate that far field, and small enough that it must be contained in the UWSC-support of any source that radiates the same far field. This means that it makes theoretical sense to look for not only the number and the locations, but also the convex geometry of sources based on the far field they radiate. The only requirement is that sources be well separated—the diameter of each convex component is strictly smaller than the distance to the other components. We also give examples to illustrate the extent to which both the convexity and well-separated properties in UWSC are necessary, i.e. we will exhibit far fields with which it is not possible to associate a unique smallest compact set or, in {{\\bb R}}^{2} , a unique smallest disjoint union of convex sets.

  3. Far-field radiation patterns of aperture antennas by the Winograd Fourier transform algorithm

    Science.gov (United States)

    Heisler, R.

    1978-01-01

    A more time-efficient algorithm for computing the discrete Fourier transform, the Winograd Fourier transform (WFT), is described. The WFT algorithm is compared with other transform algorithms. Results indicate that the WFT algorithm in antenna analysis appears to be a very successful application. Significant savings in cpu time will improve the computer turn around time and circumvent the need to resort to weekend runs.

  4. Gain and far-field patterns for phase-correcting Fresnel zone plate antennas at millimeter-wave and terahertz frequencies

    Science.gov (United States)

    Wiltse, James C.

    2007-04-01

    The Fresnel zone plate lens antenna, which provides advantages compared to a normal paraboloidal or spherical lens, has been extensively investigated in the millimeter-wave and terahertz regions. The advantages include reduced weight, volume, and attenuation and simplicity of design. The principal disadvantage is that the zone plate sometimes provides reduced gain compared to a true lens. Particularly at high millimeter-wave or terahertz frequencies the low loss of the zone plate more than compensates for the reduced directivity. This paper investigates the gains and far-field patterns for a number of cases and gives both the analysis and numerical results for the examples. These cases have dealt with large-angle designs, where the focal length (F) and diameter (D) are comparable (F/D = 0.3 to 2.5), unlike the typical optical examples. The antenna patterns are found to have beamwidths and first sidelobes that are similar to what one would obtain with a standard lens, given the same aperture illumination. Appropriate feed designs are also described. For best aperture efficiency the illumination taper is about 10 dB, and this gives first sidelobe levels of about -24dB for a circular aperture. Far-out average sidelobes are not as low as for a true lens, and this is where the gain is affected.

  5. Surface-emitting circular DFB, disk-, and ring-Bragg resonator lasers with chirped gratings. II: nonuniform pumping and far-field patterns.

    Science.gov (United States)

    Sun, Xiankai; Yariv, Amnon

    2009-01-05

    This is a continuation of our previous work [Opt. Express 16, 9155 (2008)]. In this paper we investigate the effect of nonuniform pumping on the modal properties of surface-emitting chirped circular grating lasers. By numerically solving the coupled-mode equations and matching the boundaries we compare and discuss the threshold pump levels and frequency detuning factors for three pumping profiles: uniform, Gaussian, and annular. Depending on the overlap of the pumping and modal profiles, Gaussian pumping results in the lowest threshold pump levels except for the fundamental mode of ring Bragg resonator laser, and annular pumping provides larger threshold discrimination between the fundamental and first-order modes of circular DFB and ring Bragg resonator lasers, which is favorable for single-mode operation in these lasers. We also study the far-field patterns of the fundamental modes of circular DFB, disk-, and ring- Bragg resonator lasers. Circular DFB and ring Bragg resonator lasers have the first-order dominating peak, while disk Bragg resonator laser exhibits the zeroth-order dominating peak.

  6. 塑料光纤的远场辐射图和微分模式损耗研究%Far Field Pattern and Differential Mode Attenuation of POF

    Institute of Scientific and Technical Information of China (English)

    郑史烈; 章献民; 陈抗生

    2003-01-01

    The mode coupling effect for SI-POF is studied by observing its far field radiation pattern. The results show that a transmission distance of 5 m is enough to start the mode coupling. The equilibrium mode distribution condition is established after transmitting for about 20~30 m. Differential mode attention of the same SI-POF is measured using the cut-back method. It is found that the attenuation increased with the increasing mode order. Most of the mode′s attenuation is determined to be about 150 ~180 dB/km.%通过观察塑料光纤远场辐射图,分析了阶跃型塑料光纤中的模式耦合效果.实验结果表明,阶跃型塑料光纤的模式耦合效果很明显,模式耦合从光纤传输5米左右开始发生,到传输20~30 m时,模式耦合完成,光纤末端能量分布达到稳态.采用剪断法测量了塑料光纤的微分模式损耗,发现微分模式损耗随着模阶的增加而增加,大多数模阶的微分模式损耗在150~180 dB/km范围内.

  7. 近远场变换中探头方向图的改进与比较%Comparison and Improvement of Probe Patterns in Near-to-Far Field Transformation

    Institute of Scientific and Technical Information of China (English)

    陈玉林; 杨涛; 黄文涛

    2014-01-01

    In order to improve the sidelobe precision in PNF,two new H-plane probe patterns were used in the near-to-far field transformation.The results were analyzed and compared with other two traditional H-plane probe patterns.An array antenna was measured in anechoic chamber.Two traditional methods which are Stratton-chu integral and the E-field integration method and two new methods which are the fringe current and the fringe current approaching method were used in the near-to-far field transformation.The results indicate that the sidelobe precision achieved by the two new methods is close to the international advanced level and is much higher than present level at home.Also,the method is proved to be practical.%基于进一步提高国内平面近场测量中的副瓣精度,将两种新的探头 H面方向图应用到近远场变换中,并与国内目前搭建近场测试系统所使用的两种探头方向图进行结果分析与比较。通过在微波暗室对某频段阵列天线测量,并分别用传统的 Stratton-chu积分法、E面电场法以及边缘电流法与边缘电流逼近法进行近远场变换。结果表明,新的探头方向图应用使副瓣测试精度基本接近国际先进水平,远远优于国内现有水平,具有很强的工程实用性。

  8. 开关电源远场共模电磁辐射模型及其特性研究%Common mode far field radiation model & its characteristics of a flyback power supply

    Institute of Scientific and Technical Information of China (English)

    和军平; 纪科健; 付琦; 王汝泉

    2012-01-01

    针对一台小功率反激式开关电源,从线缆共模辐射的角度辨识其主要共模电磁辐射等效激励源和辐射体结构,得出新形式的简化共模辐射模型.用Ansoft HFSS软件考察了该模型的远场辐射特性,通过与实测结果对比,验证了其有效性.最后,仿真研究了输入/输出线缆长度、电网共模射频阻抗、地平面、线缆布局等因素对共模远场辐射的作用.%In this paper, a far field common mode radiation model, including equivalent driving source, radiation structure and some other key influence factors, is identified and built up for a low-power flyback power supply based on the asymmetry line antenna theory. Then the radiation characteristics of this model are analyzed by using Ansoft HFSS finite element electromagnetic software. Further more, simulation results are compared with the experiment results to verify effectiveness of the model. In the end, the radiation role of some main influence factors, such as the length of input/output cable, the impedance of AC grid, the layout of cable position and the reflect ground, are studied in detail by simulation too.

  9. Propagation of Surface Wave Along a Thin Plasma Column and Its Radiation Pattern

    Institute of Scientific and Technical Information of China (English)

    WANG Zhijiang; ZHAO Guowei; XU Yuemin; LIANG Zhiwei; XU Jie

    2007-01-01

    Propagation of the surface waves along a two-dimensional plasma column and the far-field radiation patterns are studied in thin column approximation. Wave phase and attenuation coefficients are calculated for various plasma parameters. The radiation patterns are shown. Results show that the radiation patterns are controllable by flexibly changing the plasma length and other parameters in comparison to the metal monopole antenna. It is meaningful and instructional for the optimization of the plasma antenna design.

  10. RECONSTRUCTION OF SCATTERED FIELD FROM FAR-FIELD BY REGULARIZATION

    Institute of Scientific and Technical Information of China (English)

    Ji-jun Liu; Jin Cheng; G. Nakamura

    2004-01-01

    In this paper, we consider an inverse scattering problem for an obstacle D(∪)R2 with Robin boundary condition. By applying the point source, we give a regularizing method to recover the scattered field from the far-field pattern. Numerical implementations are also presented.

  11. Single and dual-Gregorian reflector antenna shaped beam far-field synthesis

    Science.gov (United States)

    Mehler, M. J.

    The direct far-field G.O. synthesis of shaped beam reflector antennas has recently been treated by Mehler, Tun and Adatia (1986). These authors use a synthesis technique which exploits complex coordinates and which is based on a method originally considered by Norris and Westcott (1976). They describe the synthesis of single reflector antennas which radiate both elliptical beams and European coverage patterns. Here this technique is extended to consider a class of dual reflector antennas which possess shaped main reflectors and conic subreflectors. An example is given of a Gregorian duel reflector antenna which radiates a cross-polar field significantly smaller than that radiated by single shaped reflector antennas. In addition, the behavior of the radiation pattern as a function of the reflector diameter is investigated.

  12. On Super-Planckian thermal emission in far field regime

    CERN Document Server

    Biehs, Svend-Age

    2016-01-01

    We study, in the framework of the Landauer theory, the thermal emission in far-field regime, of arbitrary indefinite planar media and finite size systems. We prove that the flux radiated by the former is bounded by the blackbody emission while, for the second, there is in principle, no upper limit demonstrating so the possibility for a super-Planckian thermal emission with finite size systems.

  13. 大功率堆积型激光阵列光束的远场分布模型%Far-field distribution pattern of high diode laser stack

    Institute of Scientific and Technical Information of China (English)

    高全华; 王晋国; 孙锋利

    2014-01-01

    为了合理地设计光学系统以整形大功率激光二极管阵列(High Diode Laser Stack)出射光束,必须准确了解HDLS的远场分布,然而对于HDLS远场分布的研究还不多。从亥姆霍兹方程出发,以激光二极管(Diode Laser)远场分布特性为基础,提出了一种新的半导体激光器阵列的远场分布模型,通过计算机仿真给出了简化DLS 模型的远场光场变化图;模型还可表示不对称的双峰结构,有一定的现实意义。%In order to design optical system to collimate laser beam,its far-field distribution should be acquired exact-ly.Based on Helmholtz equation and far-field distribution characteristic of DL(diode laser),a new far-field expression model of DLS(diode laser stack)is proposed.The changing graph of far-field intensity distribution of the simplified DLS is given by simulation. The model has some practical significance because it can express asymmetrical double-peak structure.

  14. Modal radiation patterns of baffled circular plates and membranes

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Hansen, Ole; Thomsen, Erik Vilain

    2014-01-01

    The far field velocity potential and radiation pattern of baffled circular plates and membranes are found analytically using the full set of modal velocity profiles derived from the corresponding equation of motion. The derivation is valid for a plate or membrane subjected to an external excitation...... that of a monopole, while the non-axisymmetric modes exhibit multipole behavior. Numerical results are also given, demonstrating the implications of having non-axisymmetric excitation using both a point excitation with varying eccentricity and a homogeneous excitation acting on half of the circular radiator....

  15. Far-field environment working group summary

    Energy Technology Data Exchange (ETDEWEB)

    Pearcy, E.C. [Center for Nuclear Waste Regulatory Analyses, San Antonio, TX (United States); Cady, R.E. [Nuclear Regulatory Commission, Washington, DC (United States)

    1995-09-01

    This article is a summary of the proceedings of a group discussion which took place at the Workshop on the Role of Natural Analogs in Geologic Disposal of High-Level Nuclear Waste in San Antonio, Texas on July 22-25, 1991. The working group concentrated on the subject of the potential impacts of underground disposal of high-level radioactive wastes on the far-field environment.

  16. Hybrid multilevel plane wave based near-field far-field transformation utilising combined near- and far-field translations

    Directory of Open Access Journals (Sweden)

    C. H. Schmidt

    2009-05-01

    Full Text Available The radiation of large antennas and those operating at low frequencies can be determined efficiently by near-field measurement techniques and a subsequent near-field far-field transformation. Various approaches and algorithms have been researched but for electrically large antennas and irregular measurement contours advanced algorithms with low computation complexity are required. In this paper an algorithm employing plane waves as equivalent sources and utilising efficient diagonal translation operators is presented. The efficiency is further enhanced using simple far-field translations in combination with the expensive near-field translations. In this way a low complexity near-field transformation is achieved, which works for arbitrary sample point distributions and incorporates a full probe correction without increasing the complexity.

  17. Magnetoelectric-field microwave antennas: Far-field orbital angular momenta from chiral-topology near fields

    CERN Document Server

    Berezin, M; Shavit, R

    2015-01-01

    The near fields in the proximity of a small ferrite particle with magnetic-dipolar-mode (MDM) oscillations have space and time symmetry breakings. Such MDM originated fields, called magnetoelectric (ME) fields, carry both spin and orbital angular momentums. By virtue of unique topology, ME fields are strongly different from free-space electromagnetic (EM) fields. In this paper, we show that because of chiral topology of ME fields in a nearfield region, far-field orbital angular momenta (OAM) can be observed, both numerically and experimentally. In a single element antenna, we obtain a radiation pattern with an angular squint. We reveal that in far field microwave radiation a crucial role is played by the ME energy distribution in the near-field region.

  18. Far-field characteristics of the square grooved-dielectric lens antenna for the terahertz band.

    Science.gov (United States)

    Pan, Wu; Zeng, Wei

    2016-09-10

    In order to improve the gain and directionality of a terahertz antenna, a square grooved-dielectric lens antenna based on a Fresnel zone plate is proposed. First, a diagonal horn, which is adopted as the primary feed antenna, is designed. Then, the far-field characteristics of the lens antenna are studied by using Fresnel-Kirchhoff diffraction theory and the paraxial approximation. The effects of the full-wave period, the focus diameter ratio, the subregion, and the dielectric substrate thickness on radiation characteristics are studied. The experimental results show that the proposed lens antenna has axisymmetric radiation patterns. The gain is over 26.1 dB, and the 3 dB main lobe beam width is lower than 5.6° across the operation band. The proposed lens antenna is qualified for applications in terahertz wireless communication systems.

  19. Recovering scattering obstacles by multi-frequency phaseless far-field data

    Science.gov (United States)

    Zhang, Bo; Zhang, Haiwen

    2017-09-01

    It is well known that the modulus of the far-field pattern (or phaseless far-field pattern) is invariant under translations of the scattering obstacle if only one plane wave is used as the incident field, so the shape but not the location of the obstacle can be recovered from the phaseless far-field data. This paper aims to devise an approach to break the translation invariance property of the phaseless far-field pattern. To this end, we make use of the superposition of two plane waves rather than one plane wave as the incident field. In this paper, it is mathematically proved that the translation invariance property of the phaseless far-field pattern can indeed be broken if superpositions of two plane waves are used as the incident fields for all wave numbers in a finite interval. Furthermore, a recursive Newton-type iteration algorithm in frequencies is also developed to numerically recover both the location and the shape of the obstacle simultaneously from multi-frequency phaseless far-field data. Numerical examples are also carried out to illustrate the validity of the approach and the effectiveness of the inversion algorithm.

  20. A universal expression of near-filed/far-field boundary in stratified structures

    CERN Document Server

    Li, Chao; Wang, Huai Yu; Wang, Xue Hua

    2015-01-01

    The division of the near-field and far-field zones for electromagnetic waves is important for simplifying theoretical calculations and applying far-field results. In this paper, we have studied the far-field asymptotic behaviors of dipole radiations in stratified backgrounds and obtained a universal empirical expression of near-field/far-field (NFFF) boundary. The boundary is mainly affected by lateral waves, which corresponds to branch point contributions in Sommerfeld integrals. In a semispace with a higher refractive index, the NFFF boundary is determined by a dimensional parameter and usually larger than the operating wavelength by at least two orders of magnitude. In a semispace with the lowest refractive index in the structure (usually air), the NFFF boundary is about ten wavelengths. Moreover, different treatments in the asymptotic method are discussed and numerically compared. An equivalence between the field expressions obtained from the asymptotic method and those from reciprocal theorem is demonstr...

  1. Prediction of the far field noise from wind energy farms

    Science.gov (United States)

    Shepherd, K. P.; Hubbard, H. H.

    1986-01-01

    The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

  2. Thermal extraction: enhancing thermal emission of finite size macroscopic blackbody to far-field vacuum

    CERN Document Server

    Yu, Zongfu; Zhang, Torbjorn Skauli Gang; Wang, Hailiang; Fan, Shanhui

    2012-01-01

    The understanding of far-field thermal radiation had directly led to the discovery of quantum mechanics a century ago, and is of great current practical importance for applications in energy conversions, radiative cooling, and thermal control. It is commonly assumed that for any macroscopic thermal emitter, its maximal emitted power within any given frequency range cannot exceed that of a blackbody with the same surface area. In contrast to such conventional wisdom, here we propose, and experimentally demonstrate, that the emitted power from a finite size macroscopic blackbody to far field vacuum can be significantly enhanced, within the constraint of the second law of thermodynamics. To achieve such an enhancement, the thermal body needs to have internal electromagnetic density of states (DOS) greater than that of vacuum, and one needs to provide a thermal extraction mechanism to enable the contributions of all internal modes to far field radiation.

  3. From near-field to far-field coupling in the third dimension: retarded interaction of particle plasmons.

    Science.gov (United States)

    Taubert, Richard; Ameling, Ralf; Weiss, Thomas; Christ, André; Giessen, Harald

    2011-10-12

    We study the transition from the near-field to the far-field coupling regime of particle plasmons in a three-dimensional geometry. In the far-field regime, retardation plays the dominant role and the plasmonic resonances are radiatively coupled. When the spatial arrangement of the oscillators is matched to their resonance wavelength, superradiant-like effects are observed.

  4. Influence of turbulent atmosphere on the far-field coherent combined beam quality

    Institute of Scientific and Technical Information of China (English)

    Pu Zhou; Zejin Liu; Xiaojun Xu; Xiaolin Wang; Xiao Li; Zilun Chen

    2008-01-01

    Propagation of coherent combined laser beams in turbulent atmosphere is numerically studied based on the extended Huygens-Fresnel principle. By choosing beam propagation factor (BPF) and beam quality factor (BQ) to characterize the far-field irradiance distribution properties, the influence of turbulence on far-field coherent combined beam quality is studied in detail. The investigation reveals that with the coherence length decreasing, the irradiance distribution pattern evolves from typical non-Gaussian shape with multiple side-lobes into Gaussian shape which is seen in the incoherent combining case. In weak turbulent atmosphere, the far-field beam quality suffers less when the 1aser array gets more compact and operates at a longer wavelength. In strong turbulent atmosphere, the far-field beam quality degrades into the incoherent combining case without any relationship with the fill factor and laser wavelength.

  5. Analysis of RF Front-End Performance of Reconfigurable Antennas with RF Switches in the Far Field

    Directory of Open Access Journals (Sweden)

    Insu Yeom

    2014-01-01

    Full Text Available The RF front-end performances in the far-field condition of reconfigurable antennas employing two commonly used RF switching devices (PIN diodes and RF-MEMS switches were compared. Two types of antennas (monopole and slot representing general direct/coupled feed types were used for the reconfigurable antennas to compare the excited RF power to the RF switches by the reconfigurable antenna types. For the switching operation of the antennas, a biasing circuit was designed and embedded in the same antenna board, which included a battery to emphasize the antenna’s adaptability to mobile devices. The measurement results of each reconfigurable antenna (radiation patterns and return losses are presented in this study. The receiving power of the reference antenna was measured by varying the transmitting power of the reconfigurable antennas in the far-field condition. The receiving power was analyzed using the “Friis transmission equation” and compared for two switching elements. Based on the results of these measurements and comparisons, we discuss what constitutes an appropriate switch device and antenna type for reconfigurable antennas of mobile devices in the far-field condition.

  6. Natural analogs for far-field environment/hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Hoxie, D.T. [Geological Survey, Denver, CO (United States)

    1995-09-01

    This paper discusses the applicability of natural-analog studies to characterize far-field conditions in the vicinity of geologic repository systems for the disposal of high-level radioactive wastes. Conditions in the far field are determined by the natural state and evolution of the repository geosphere and its environment.

  7. Plasmonic and Mie scattering control of far-field interference for regular ripple formation on various material substrates.

    Science.gov (United States)

    Obara, Go; Maeda, Naoki; Miyanishi, Tomoya; Terakawa, Mitsuhiro; Nedyalkov, Nikolay N; Obara, Minoru

    2011-09-26

    We present experimental and theoretical results on plasmonic control of far-field interference for regular ripple formation on semiconductor and metal. Experimental observation of interference ripple pattern on Si substrate originating from the gold nanosphere irradiated by femtosecond laser is presented. Gold nanosphere is found to be an origin for ripple formation. Arbitrary intensity ripple patterns are theoretically controllable by depositing desired plasmonic and Mie scattering far-field pattern generators. The plasmonic far-field generation is demonstrated not only by metallic nanostructures but also by the controlled surface structures such as ridge and trench structures on various material substrates.

  8. Near-field measurements of the even-order harmonics undetectable in far-field measurements

    Science.gov (United States)

    Moiseyev, Nimrod

    2016-12-01

    Even-order harmonics (EOHs) are generated for oriented molecules and for atoms under specific conditions. Here, we focus on the most common situations where EOHs are not observed in far-field measurements. We propose an experiment to show that the EOHs are produced close to the nucleus but are not detected in the far-field measurements due to destructive interferences of the propagated EOHs of the emitted radiation. However, Rydberg gas atoms (e.g., rubidium), which are out of the focus of the laser beam, are expected to be ionized due to their weak interaction with a specific EOH of helium, which is not observed by the far-field detector. The ionization energy of the Rydberg gas atoms should be in resonance with the single-photon energy of a specific EOH.

  9. Investigation of various behaviors of near- and far-field diffractions from multiplicatively separable structures in the x and y directions, and a detailed study of the near-field diffraction patterns of 2D multiplicatively separable periodic structures using the contrast variation method

    Science.gov (United States)

    Rasouli, Saifollah; Hebri, Davud; Khazaei, Ali Mohammad

    2017-09-01

    In this paper, first a detailed investigation of the various behaviors of the near- and far-field diffractions from multiplicatively separable (MS) structures in the x and y directions is presented. It is shown that in near-field propagation, the diffraction pattern of a 2D MS structure is same as the product of the corresponding near-field diffractions of the 1D individual components of the structure. For the far-field diffraction, although the resulting diffraction pattern is not equal to the product of the individual 1D structures’ diffraction patterns, we show that it is still a 2D MS pattern. Second, a detailed theoretical investigation of the contrast enhancement effect for the multiplication of two 1D orthogonal intensity patterns (not necessarily periodic) is presented. By merging the above-mentioned facts, we deduced that in near-field diffraction, the contrast of the diffraction pattern of a 2D MS structure is always larger than the contrast of each of the diffraction patterns of the corresponding individual 1D structures. In the second part of this paper, we implement the intensity contrast as a quantity to describe self-images of the 2D MS periodic structures. For the first time, two very important results are obtained based on the contrast enhancement effect. We show that the depth of focus of the self-images increases for the 2D periodic structures in comparing to their corresponding 1D structures. We also predict the existence of additional self-images in addition to the Talbot images located at the least common multiple of each of the individual 1D Talbot distances for the 2D MS periodic structures. In addition, in this work we present a very straightforward manner for the prediction of the 1D or 2D forms of the diffraction pattern and the direction of the 1D pattern strips at given propagation distances from the 2D structure by introducing another intensity-contrast-based parameter. Furthermore, we show that the diffraction pattern of a 2D MS

  10. Spatially resolved surface topography retrieved from far-field intensity scattering measurements.

    Science.gov (United States)

    Zerrad, Myriam; Lequime, Michel; Amra, Claude

    2014-02-01

    A far-field setup based on the fast and simultaneous recording of 1 million intensity angle-resolved-light-scattering patterns allows both to reconstruct surface topography and to cancel local defects in this topography. A spectral analysis is performed on measured data and allows to extract roughness and slopes mapping of a surface taking into account the spectral bandpass.

  11. Far field scattering pattern of differently structured butterfly scales

    NARCIS (Netherlands)

    Giraldo, M. A.; Yoshioka, S.; Stavenga, D. G.

    2008-01-01

    The angular and spectral reflectance of single scales of five different butterfly species was measured and related to the scale anatomy. The scales of the pierids Pieris rapae and Delias nigrina scatter white light randomly, in close agreement with Lambert's cosine law, which can be well understood

  12. Analytical structure of Hermite Gaussian beam in far field

    Institute of Scientific and Technical Information of China (English)

    Zhou Guo-Quan; Chen Liang; Chu Xiu-Xiang

    2007-01-01

    Based on the vectorial structure of electromagnetic beam and the method of stationary phase, the analytical structure of Hermite Gaussian beam in far field is presented. The structural energy flux distributions are also investigated in the far field. The structural pictures of some Hermite Gaussian beams are depicted in the far field. As the structure of Hermite Gaussian beam is dominated by the transverse mode numbers and the initial transverse Gaussian half width, it is more complex than that of Gaussian beam. The ratios of the structural energy fluxes to the whole energy flux are independent of the transverse mode numbers and the initial transverse Gaussian half width. The present research reveals the internal vectorial structure of Hermite Gaussian beam from other viewpoint.

  13. Spectrally resolved far-fields of terahertz quantum cascade lasers

    CERN Document Server

    Brandstetter, Martin; Krall, Michael; Kainz, Martin A; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron M; Strasser, Gottfried; Unterrainer, Karl

    2016-01-01

    We demonstrate a convenient and fast method to measure the spectrally resolved far-fields of multimode terahertz quantum cascade lasers by combining a microbolometer focal plane array with an FTIR spectrometer. Far-fields of fundamental TM0 and higher lateral order TM1 modes of multimode Fabry-P\\'erot type lasers have been distinguished, which very well fit to the results obtained by a 3D finite-element simulation. Furthermore, multimode random laser cavities have been investigated, analyzing the contribution of each single laser mode to the total far-field. The presented method is thus an important tool to gain in-depth knowledge of the emission properties of multimode laser cavities at terahertz frequencies, which become increasingly important for future sensing applications.

  14. Far-field Fano resonance in nanoring lattices modeled from extracted, point dipole polarizability

    Energy Technology Data Exchange (ETDEWEB)

    DeJarnette, Drew; Forcherio, Gregory T. [Microelectronics and Photonics Graduate Program, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Blake, Phillip [Department of Chemical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Keith Roper, D., E-mail: dkroper@uark.edu [Microelectronics and Photonics Graduate Program, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Department of Chemical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

    2014-01-14

    Coupling and extinction of light among particles representable as point dipoles can be characterized using the coupled dipole approximation (CDA). The analytic form for dipole polarizability of spheroidal particles supports rapid electrodynamic analysis of nanoparticle lattices using CDA. However, computational expense increases for complex shapes with non-analytical polarizabilities which require discrete dipole (DDA) or higher order approximations. This work shows fast CDA analysis of assembled nanorings is possible using a single dipole nanoring polarizability extrapolated from a DDA calculation by summing contributions from individual polarizable volume elements. Plasmon resonance wavelengths of nanorings obtained using extracted polarizabilities blueshift as wall dimensions-to-inner radius aspect ratio increases, consistent with published theory and experiment. Calculated far-field Fano resonance energy maximum and minimum wavelengths were within 1% of full volume element results. Considering polarizability allows a more complete physical picture of predicting plasmon resonance location than metal dielectric alone. This method reduces time required for calculation of diffractive coupling more than 40 000-fold in ordered nanoring systems for 400–1400 nm incident wavelengths. Extension of this technique beyond nanorings is possible for more complex shapes that exhibit dipolar or quadrupole radiation patterns.

  15. Near-Field to Far-Field Transformation Techniques with Spiral Scannings: A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    Renato Cicchetti

    2014-01-01

    Full Text Available An overview of the near-field-far-field (NF-FF transformation techniques with innovative spiral scannings, useful to derive the radiation patterns of the antennas commonly employed in the modern wireless communication systems, is provided in this paper. The theoretical background and the development of a unified theory of the spiral scannings for quasi-spherical and nonspherical antennas are described, and an optimal sampling interpolation expansion to evaluate the probe response on a quite arbitrary rotational surface from a nonredundant number of its samples, collected along a proper spiral wrapping it, is presented. This unified theory can be applied to spirals wrapping the conventional scanning surfaces and makes it possible to accurately reconstruct the NF data required by the NF-FF transformation employing the corresponding classical scanning. A remarkable reduction of the measurement time is so achieved, due to the use of continuous and synchronized movements of the positioning systems and to the reduced number of needed NF measurements. Some numerical and experimental results relevant to the spherical spiral scanning case when dealing with quasi-planar and electrically long antennas are shown.

  16. Study of high speed complex number algorithms. [for determining antenna for field radiation patterns

    Science.gov (United States)

    Heisler, R.

    1981-01-01

    A method of evaluating the radiation integral on the curved surface of a reflecting antenna is presented. A three dimensional Fourier transform approach is used to generate a two dimensional radiation cross-section along a planer cut at any angle phi through the far field pattern. Salient to the method is an algorithm for evaluating a subset of the total three dimensional discrete Fourier transform results. The subset elements are selectively evaluated to yield data along a geometric plane of constant. The algorithm is extremely efficient so that computation of the induced surface currents via the physical optics approximation dominates the computer time required to compute a radiation pattern. Application to paraboloid reflectors with off-focus feeds in presented, but the method is easily extended to offset antenna systems and reflectors of arbitrary shapes. Numerical results were computed for both gain and phase and are compared with other published work.

  17. Novel On-wafer Radiation Pattern Measurement Technique for MEMS Actuator Based Reconfigurable Patch Antennas

    Science.gov (United States)

    Simons, Rainee N.

    2002-01-01

    The paper presents a novel on-wafer, antenna far field pattern measurement technique for microelectromechanical systems (MEMS) based reconfigurable patch antennas. The measurement technique significantly reduces the time and the cost associated with the characterization of printed antennas, fabricated on a semiconductor wafer or dielectric substrate. To measure the radiation patterns, the RF probe station is modified to accommodate an open-ended rectangular waveguide as the rotating linearly polarized sampling antenna. The open-ended waveguide is attached through a coaxial rotary joint to a Plexiglas(Trademark) arm and is driven along an arc by a stepper motor. Thus, the spinning open-ended waveguide can sample the relative field intensity of the patch as a function of the angle from bore sight. The experimental results include the measured linearly polarized and circularly polarized radiation patterns for MEMS-based frequency reconfigurable rectangular and polarization reconfigurable nearly square patch antennas, respectively.

  18. Different Designs of Dual-Focus Perforated Transmitarray Antenna in Near/Far-Field Region

    Directory of Open Access Journals (Sweden)

    H. Abd El-Azem Malhat

    2016-01-01

    Full Text Available Designs of the single-focus and multi-focused transmitarray antennas for the near-field (NF or/and far-field (FF applications have been introduced. Perforated dielectric single sheet is used for transmitarray design for simple configuration. Single-focus transmitarray for the far-field and the near-field are obtained. The radiation characteristics of 13×13 unit-cells transmitarray in the near-field and the far-field region have been investigated. A single structure multi-focus transmitarray is designed using the chess-board arrangement of the unit-cells elements. Multi-focus transmitarray for FF/FF, FF/NF, and NF/NF have been designed and investigated. The phase distribution and the corresponding holes radii for the first quadrant of the multi-focus transmitarray are presented. The radiation characteristics of different array configuration have been investigated and analyzed using full-wave simulator CST Microwave Studio.

  19. Near- and Far-Field Optical Response of Eccentric Nanoshells.

    Science.gov (United States)

    Peña-Rodríguez, Ovidio; Díaz-Núñez, Pablo; Rodríguez-Iglesias, Vladimir; Montaño-Priede, Luis; Rivera, Antonio; Pal, Umapada

    2017-12-01

    We study the optical response of eccentric nanoshells (i.e., spherical nanoparticles with an eccentric spherical inclusion) in the near and the far field through finite-difference time-domain simulations. Plasmon hybridization theory is used to explain the obtained results. The eccentricity generates a far-field optical spectrum with various plasmon peaks. The number, position, and width of the peaks depend on the core offset. Near-field enhancements in the surroundings of these structures are significantly larger than those obtained for equivalent concentric nanoshells and, more importantly, they are almost independent of the illumination conditions. This opens up the door for using eccentric nanoshells in applications requiring intense near-field enhancements.

  20. Far-Field Microscopy of Sparse Subwavelength Objects

    CERN Document Server

    Szameit, A; Dana, H; Steiner, S; Gazit, S; Cohen-Hyams, T; Bullkich, E; Cohen, O; Eldar, Y C; Shoham, S; Kley, E B; Segev, M

    2010-01-01

    We present the experimental reconstruction of sub-wavelength features from the far-field of sparse optical objects. We show that it is sufficient to know that the object is sparse, and only that, and recover 100 nm features with the resolution of 30 nm, for an illuminating wavelength of =532 nm. Our technique works in real-time, requires no scanning, and can be implemented in all existing microscopes - optical and non-optical.

  1. Fusion of regularized femtosecond filaments in air: far field on-axis emission

    Science.gov (United States)

    Shipilo, D. E.; Panov, N. A.; Sunchugasheva, E. S.; Mokrousova, D. V.; Andreeva, V. A.; Kosareva, O. G.; Seleznev, L. V.; Savel'ev, A. B.; Ionin, A. A.; Chin, S. L.

    2016-11-01

    The fusion of several coherent 800 nm femtosecond filaments is induced experimentally and numerically by transmitting a beam through a mask with circular apertures followed by the focusing lens. The far-field image of the four-filament fusion region reveals bright on-axis maximum and differs drastically from the diffraction pattern of a low energy beam propagating through the mask in the linear regime. In 3D+time numerical simulations with the carrier wave resolved we show a factor-of-5 saturable growth in the peak plasma density with successive increase in the number of mask openings. An overall spectral blueshift of the fundamental and the third harmonics follows the plasma density increase. The simulated far-field on-axis emission agrees with the experiment and serves as the indication of nonlinear interaction in the fusion region.

  2. Far-field super-resolution imaging of resonant multiples

    KAUST Repository

    Guo, Bowen

    2016-05-20

    We demonstrate for the first time that seismic resonant multiples, usually considered as noise, can be used for super-resolution imaging in the far-field region of sources and receivers. Tests with both synthetic data and field data show that resonant multiples can image reflector boundaries with resolutions more than twice the classical resolution limit. Resolution increases with the order of the resonant multiples. This procedure has important applications in earthquake and exploration seismology, radar, sonar, LIDAR (light detection and ranging), and ultrasound imaging, where the multiples can be used to make high-resolution images.

  3. Coherence vortices of partially coherent beams in the far field

    Institute of Scientific and Technical Information of China (English)

    Liu Pu-Sheng; Lü Bai-da

    2007-01-01

    Based on the propagation law of cross-spectral density function, studied in this paper are the coherence vortices of partially coherent, quasi-monochromatic singular beams with Gaussian envelope and Schell-model correlator in the far field, where our main attention is paid to the evolution of far-field coherence vortices into intensity vortices of fully coherent beams. The results show that, although there are usually no zeros of intensity in partially coherent beams with Gaussian envelope and Schell-model correlator, zeros of spectral degree of coherence exist. The coherence vortices of spectral degree of coherence depend on the relative coherence length, mode index and positions of pairs of points.If a point and mode index are kept fixed, the position of coherence vortices changes with the increase of the relative coherence length. For the low coherent case there is a circular phase dislocation. In the coherent limit coherence vortices become intensity vortices of fully coherent Laguerre-Gaussian beams.

  4. Fluorescent Nanowire Ring Illumination for Wide-Field Far-Field Subdiffraction Imaging

    Science.gov (United States)

    Liu, Xiaowei; Kuang, Cuifang; Hao, Xiang; Pang, Chenlei; Xu, Pengfei; Li, Haifeng; Liu, Ying; Yu, Chao; Xu, Yingke; Nan, Di; Shen, Weidong; Fang, Yue; He, Lenian; Liu, Xu; Yang, Qing

    2017-02-01

    Here we demonstrate an active method which pioneers in utilizing a combination of a spatial frequency shift and a Stokes frequency shift to enable wide-field far-field subdiffraction imaging. A fluorescent nanowire ring acts as a localized source and is combined with a film waveguide to produce omnidirectional illuminating evanescent waves. Benefitting from the high wave vector of illumination, the high spatial frequencies of an object can be shifted to the passband of a conventional imaging system, contributing subwavelength spatial information to the far-field image. A structure featuring 70-nm-wide slots spaced 70 nm apart has been resolved at a wavelength of 520 nm with a 0.85 numerical aperture standard objective based on this method. The versatility of this approach has been demonstrated by imaging integrated chips, Blu-ray DVDs, biological cells, and various subwavelength 2D patterns, with a viewing area of up to 1 0 0 0 μ m2 , which is one order of magnitude larger than the previous far-field and full-field nanoscopy methods. This new resolving technique is label-free, is conveniently integrated with conventional microscopes, and can potentially become an important tool in cellular biology, the on-chip industry, as well as other fields requiring wide-field nanoscale visualization.

  5. Modeling the radiation pattern of LEDs.

    Science.gov (United States)

    Moreno, Ivan; Sun, Ching-Cherng

    2008-02-01

    Light-emitting diodes (LEDs) come in many varieties and with a wide range of radiation patterns. We propose a general, simple but accurate analytic representation for the radiation pattern of the light emitted from an LED. To accurately render both the angular intensity distribution and the irradiance spatial pattern, a simple phenomenological model takes into account the emitting surfaces (chip, chip array, or phosphor surface), and the light redirected by both the reflecting cup and the encapsulating lens. Mathematically, the pattern is described as the sum of a maximum of two or three Gaussian or cosine-power functions. The resulting equation is widely applicable for any kind of LED of practical interest. We accurately model a wide variety of radiation patterns from several world-class manufacturers.

  6. Far-field superresolution by imaging of resonance scattering

    KAUST Repository

    Schuster, Gerard T.

    2014-10-31

    We show that superresolution imaging in the far-field region of the sources and receivers is theoretically and practically possible if migration of resonant multiples is employed. A resonant multiple is one that bounces back and forth between two scattering points; it can also be the multiple between two smoothly varying interfaces as long as the reflection wave paths partially overlap and reflect from the same Fresnel zone. For a source with frequency f, compared to a one-way trip, N round trips in propagating between two scatterers increase the effective frequency by 2N × f and decrease the effective wavelength by λ/(2N). Thus, multiples can, in principle, be used as high-frequency probes to estimate detailed properties of layers. Tests with both synthetic and field data validate this claim. Improved resolution by multiple imaging is not only feasible for crustal reflections, but might be applicable to mantle and core reverberations recorded by earthquake seismologists.

  7. Far-Field Tsunami Hazard in New Zealand Ports

    Science.gov (United States)

    Borrero, Jose C.; Goring, Derek G.; Greer, S. Dougal; Power, William L.

    2015-03-01

    We present the results of a numerical modeling study investigating the effects of far-field tsunamis in New Zealand ports. Four sites (Marsden Point, Tauranga, Harbor, Port Taranaki and Lyttelton Harbor) were selected based on a combination of factors such as economic importance and the availability of historical and/or instrumental data. Numerical models were created using the ComMIT tsunami modeling tool and the Method Of Splitting Tsunami (MOST) hydrodynamic model. Comparison of model results to measured data from recent historical events showed that, for particular sites and events, the model correlated well with the timing and amplitude of the observed tsunami, and, in most cases, there was generally good agreement between the and modeled tsunami heights and current speeds. A sensitivity analysis for tsunami heights and current speeds was conducted using a suite of large ( M W 9) tsunamigenic earthquake sources situated at regular 15° intervals in azimuth along the Pacific Rim while another set of scenarios focused on regional tsunami sources in the Southwest Pacific. Model results were analyzed for tsunami heights and current speeds as a function of the source region. In terms of currents, the analysis identified where speeds were greatest and which source was responsible. Results suggested that tsunamis originating from Central America produced the strongest response in New Zealand. The modeling was also used to determine the timing and duration of potentially dangerous current speeds as well as minimum `safe depths' for vessel evacuation offshore. This study was motivated by the desire to reduce damage and operational losses via improved forecasting of far-field tsunamis at New Zealand ports. It is important that forecasts are accurate since tsunami damage to ships and facilities is expensive and can be mitigated given timely warnings and because preventable false alarms are also costly in terms of lost productivity. The modeling presented here will

  8. An Exact Line Integral Representation of the Physical Optics Far Field from Plane PEC Scatterers Illuminnated by Hertzian Dipoles

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Meincke, Peter; Jørgensen, Erik;

    2003-01-01

    We derive a line integral representation of the physical optics scattered far field that yields the exact same result as the conventional surface radiation integral. This representation applies to a perfectly electrically conducting plane scatterer illuminated by electric or magnetic Hertzian...... dipoles. The source and observation points can take on almost arbitrary positions. To illustrate the exactness and efficiency of the new line integral, numerical comparisons with the conventional surface radiation integral are carried out....

  9. Near-field and far-field engineering of semiconductor lasers

    Science.gov (United States)

    Yu, Nanfang

    Plasmonics focuses on the interaction between light and metallic films or nanostructures. In the last two decades, intensive research efforts were devoted to exploring the extremely broad applications of plasmonics. My research combines the versatility of plasmonics with active light sources, i.e., quantum cascade lasers (QCLs). This thesis focuses on the application of plasmonics in near-field and far-field engineering of semiconductor lasers, specifically, subwavelength focusing in the near-field, and laser beam collimation and polarization control. The first chapter of this thesis lays out fundamental materials necessary for understanding the following chapters. Systematic simulation and experimental results are presented in Chapter 2 to demonstrate that the integration of a suitably designed one dimensional or two dimensional plasmonic structures on the facet of QCLs can reduce the beam divergence by more than one order of magnitude. The devices with optimized collimators preserve a high output power, comparable to that of the unpatterned lasers. Chapter 3 demonstrates that the polarization state of the output of semiconductor lasers can be controlled by defining plasmonic structures on the laser facet. An integrated plasmonic polarizer can project the polarization of a semiconductor laser onto other directions. By patterning a facet with two orthogonal grating-aperture structures, a QCL can produce emission consisting of a superposition of a linearly and right-circularly polarized light, a first step towards a circularly-polarized laser. Chapter 4 presents experimental work on the coupled-rod antennas and the bowtie antennas patterned on the facet of QCLs. Both designs can provide an optical field confinement on the order of lambda/50 and with peak intensity on the order of 1 GW/cm2 in the antenna gap. The bowtie devices are more advanced due to better confinement of light into a single spot. Chapter 5 and 6 discuss two side research topics. Chapter 5

  10. Far-field Diffraction Properties of Annular Walsh Filters

    Directory of Open Access Journals (Sweden)

    Pubali Mukherjee

    2013-01-01

    Full Text Available Annular Walsh filters are derived from the rotationally symmetric annular Walsh functions which form a complete set of orthogonal functions that take on values either +1 or −1 over the domain specified by the inner and outer radii of the annulus. The value of any annular Walsh function is taken as zero from the centre of the circular aperture to the inner radius of the annulus. The three values 0, +1, and −1 in an annular Walsh function can be realized in a corresponding annular Walsh filter by using transmission values of zero amplitude (i.e., an obscuration, unity amplitude and zero phase, and unity amplitude and phase, respectively. Not only the order of the Walsh filter but also the size of the inner radius of the annulus provides an additional degree of freedom in tailoring of point spread function by using these filters for pupil plane filtering in imaging systems. In this report, we present the far-field amplitude characteristics of some of these filters to underscore their potential for effective use in several demanding applications like high-resolution microscopy, optical data storage, microlithography, optical encryption, and optical micromanipulation.

  11. Parameter governing the far-field features of round jets

    Science.gov (United States)

    Xia, Xi; Mohseni, Kamran

    2016-10-01

    This study is inspired by the observation and hypothesis that the spreading and decay behaviors of a jet directly depend on the momentum-mixing mechanism between the jet and surrounding fluid. This mixing behavior is dictated by the kinematic viscosity ν for a laminar jet, which can be dramatically enhanced in a turbulent flow and is represented by the eddy viscosity ɛ . Similarly, pulsation in a synthetic jet is identified as another mechanism for enhancing mixing, which can be captured by an enhanced eddy viscosity beyond what is observed in a corresponding turbulent continuous jet. To this end, an effective-eddy-viscosity concept is proposed to model any excitation of a jet that could result in enhanced mixing beyond what is predicted by the kinematic viscosity. Our previous study found that ɛ is actuator dependent and its relationship with the spreading or decay behavior of a jet is not obvious. To remove the actuator dependence, this study performs a dimensional analysis to relate the spreading and decay behaviors to a scaled effective eddy viscosity ɛ /√{K } (K is the momentum flux). This quantity physically represents a competition between the radial diffusion and the axial convection of the jet axial momentum. The experimental results confirm that ɛ /√{K } governs the spreading and decay rates of the far field for any round jets.

  12. A Reconfigurable Radiation Pattern Annular Slot Antenna

    OpenAIRE

    Aziz, NA; Radhi, A; Nilavalan, R

    2016-01-01

    This paper contemplate a theoretical analysis of a pattern reconfigurable antenna using annular slot antenna operating in low frequency. A shorting pin is inserted to allow the annular slot antenna to have an omnidirectional radiation pattern like a monopole antenna. The reconfigurable antenna consists of numerous metal cylinders arranged around the annular slot antenna. By controlling pin diodes associated with the metal cylinders, the antenna is capable of working up in different dire...

  13. Far-Field and Middle-Field Vertical Velocities Associated with Megathrust Earthquakes

    Science.gov (United States)

    Fleitout, L.; Trubienko, O.; Klein, E.; Vigny, C.; Garaud, J.; Shestakov, N.; Satirapod, C.; Simons, W. J.

    2013-12-01

    The recent megathrust earthquakes (Sumatra, Chili and Japan) have induced far-field postseismic subsidence with velocities from a few mm/yr to more than 1cm/yr at distances from 500 to 1500km from the earthquake epicentre, for several years following the earthquake. This subsidence is observed in Argentina, China, Korea, far-East Russia and in Malaysia and Thailand as reported by Satirapod et al. ( ASR, 2013). In the middle-field a very pronounced uplift is localized on the flank of the volcanic arc facing the trench. This is observed both over Honshu, in Chile and on the South-West coast of Sumatra. In Japan, the deformations prior to Tohoku earthquake are well measured by the GSI GPS network: While the East coast was slightly subsiding, the West coast was raising. A 3D finite element code (Zebulon-Zset) is used to understand the deformations through the seismic cycle in the areas surrounding the last three large subduction earthquakes. The meshes designed for each region feature a broad spherical shell portion with a viscoelastic asthenosphere. They are refined close to the subduction zones. Using these finite element models, we find that the pattern of the predicted far-field vertical postseismic displacements depends upon the thicknesses of the elastic plate and of the low viscosity asthenosphere. A low viscosity asthenosphere at shallow depth, just below the lithosphere is required to explain the subsidence at distances from 500 to 1500km. A thick (for example 600km) asthenosphere with a uniform viscosity predicts subsidence too far away from the trench. Slip on the subduction interface is unable tot induce the observed far-field subsidence. However, a combination of relaxation in a low viscosity wedge and slip or relaxation on the bottom part of the subduction interface is necessary to explain the observed postseismic uplift in the middle-field (volcanic arc area). The creep laws of the various zones used to explain the postseismic data can be injected in

  14. Optical characterization of OLED emitter properties by radiation pattern analyses

    Energy Technology Data Exchange (ETDEWEB)

    Flaemmich, Michael

    2011-09-08

    Researches in both, academia and industry are investigating optical loss channels in OLED layered systems by means of optical simulation tools in order to derive promising concepts for a further enhancement of the overall device performance. Besides other factors, the prospects of success of such optimization strategies rely severely on the credibility of the optical input data. The present thesis provides a guideline to measure the active optical properties of OLED emitter materials in situ by radiation pattern analyses. Reliable and widely applicable methods are introduced to determine the internal electroluminescence spectrum, the profile of the emission zone, the dipole emitter orientation, and the internal luminescence quantum efficiency of emissive materials from the optical far field emission of OLEDs in electrical operation. The proposed characterization procedures are applied to sets of OLEDs containing both, fluorescent polymeric materials as well as phosphorescent small-molecular emitters, respectively. On the one hand, quite expected results are obtained. On the other hand, several novel and truly surprising results are found. Most importantly, this thesis contains the first report of a non-isotropic, mainly parallel emitter orientation in a phosphorescent small-molecular guest-host system (Ir(MDQ)2(acac) in a-NPD). Due to the latter result, emitter orientation based optimization of phosphorescent OLEDs seems to be within reach. Since parallel dipoles emit preferably into air, the utilization of smart emissive materials with advantageous molecular orientation is capable to boost the efficiency of phosphorescent OLEDs by 50%. Materials design, the influence of the matrix material and the substrate, as well as film deposition conditions are just a few parameters that need to be studied further in order to exploit the huge potential of the dipole emitter orientation in phosphorescent OLEDs.

  15. Adaptive acoustic energy delivery to near and far fields using foldable, tessellated star transducers

    Science.gov (United States)

    Zou, Chengzhe; Harne, Ryan L.

    2017-05-01

    Methods of guiding acoustic energy arbitrarily through space have long relied on digital controls to meet performance needs. Yet, more recent attention to adaptive structures with unique spatial configurations has motivated mechanical signal processing (MSP) concepts that may not be subjected to the same functional and performance limitations as digital acoustic beamforming counterparts. The periodicity of repeatable structural reconfiguration enabled by origami-inspired tessellated architectures turns attention to foldable platforms as frameworks for MSP development. This research harnesses principles of MSP to study a tessellated, star-shaped acoustic transducer constituent that provides on-demand control of acoustic energy guiding via folding-induced shape reconfiguration. An analytical framework is established to probe the roles of mechanical and acoustic geometry on the far field directivity and near field focusing of sound energy. Following validation by experiments and verification by simulations, parametric studies are undertaken to uncover relations between constituent topology and acoustic energy delivery to arbitrary points in the free field. The adaptations enabled by folding of the star-shaped transducer reveal capability for restricting sound energy to angular regions in the far field while also introducing means to modulate sound energy by three orders-of-magnitude to locations near to the transducer surface. In addition, the modeling philosophy devised here provides a valuable approach to solve general sound radiation problems for foldable, tessellated acoustic transducer constituents of arbitrary geometry.

  16. Prediction and measurement of the electromagnetic environment of high-power medium-wave and short-wave broadcast antennas in far field.

    Science.gov (United States)

    Tang, Zhanghong; Wang, Qun; Ji, Zhijiang; Shi, Meiwu; Hou, Guoyan; Tan, Danjun; Wang, Pengqi; Qiu, Xianbo

    2014-12-01

    With the increasing city size, high-power electromagnetic radiation devices such as high-power medium-wave (MW) and short-wave (SW) antennas have been inevitably getting closer and closer to buildings, which resulted in the pollution of indoor electromagnetic radiation becoming worsened. To avoid such radiation exceeding the exposure limits by national standards, it is necessary to predict and survey the electromagnetic radiation by MW and SW antennas before constructing the buildings. In this paper, a modified prediction method for the far-field electromagnetic radiation is proposed and successfully applied to predict the electromagnetic environment of an area close to a group of typical high-power MW and SW wave antennas. Different from currently used simplified prediction method defined in the Radiation Protection Management Guidelines (H J/T 10. 3-1996), the new method in this article makes use of more information such as antennas' patterns to predict the electromagnetic environment. Therefore, it improves the prediction accuracy significantly by the new feature of resolution at different directions. At the end of this article, a comparison between the prediction data and the measured results is given to demonstrate the effectiveness of the proposed new method. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Far-field radially polarized focal spot from plasmonic spiral structure combined with central aperture antenna

    Science.gov (United States)

    Mao, Lei; Ren, Yuan; Lu, Yonghua; Lei, Xinrui; Jiang, Kang; Li, Kuanguo; Wang, Yong; Cui, Chenjing; Wen, Xiaolei; Wang, Pei

    2016-03-01

    Manipulation of a vector micro-beam with an optical antenna has significant potentials for nano-optical technology applications including bio-optics, optical fabrication, and quantum information processing. We have designed and demonstrated a central aperture antenna within an Archimedean spiral that extracts the bonding plasmonic field from a surface to produce a new vector focal spot in far-field. The properties of this vector focal field are revealed by confocal microscopy and theoretical simulations. The pattern, polarization and phase of the focal field are determined by the incident light and by the chirality of the Archimedean spiral. For incident light with right-handed circular polarization, the left-handed spiral (one-order chirality) outputs a micro-radially polarized focal field. Our results reveal the relationship between the near-field and far-field distributions of the plasmonic spiral structure, and the structure has the potential to lead to advances in diverse applications such as plasmonic lenses, near-field angular momentum detection, and optical tweezers.

  18. Far-field radially polarized focal spot from plasmonic spiral structure combined with central aperture antenna

    Science.gov (United States)

    Mao, Lei; Ren, Yuan; Lu, Yonghua; Lei, Xinrui; Jiang, Kang; Li, Kuanguo; Wang, Yong; Cui, Chenjing; Wen, Xiaolei; Wang, Pei

    2016-01-01

    Manipulation of a vector micro-beam with an optical antenna has significant potentials for nano-optical technology applications including bio-optics, optical fabrication, and quantum information processing. We have designed and demonstrated a central aperture antenna within an Archimedean spiral that extracts the bonding plasmonic field from a surface to produce a new vector focal spot in far-field. The properties of this vector focal field are revealed by confocal microscopy and theoretical simulations. The pattern, polarization and phase of the focal field are determined by the incident light and by the chirality of the Archimedean spiral. For incident light with right-handed circular polarization, the left-handed spiral (one-order chirality) outputs a micro-radially polarized focal field. Our results reveal the relationship between the near-field and far-field distributions of the plasmonic spiral structure, and the structure has the potential to lead to advances in diverse applications such as plasmonic lenses, near-field angular momentum detection, and optical tweezers. PMID:27009383

  19. Far-field characterization of the thermal dynamics in lasing microspheres

    CERN Document Server

    Ramirez, J M; Capuj, N E; Berencen, Y; Pitanti, A; Garrido, B; Tredicucci, A

    2015-01-01

    This work reports the dynamical thermal behavior of lasing microspheres placed on a dielectric substrate while they are homogeneously heated-up by the top-pump laser used to excite the active medium. The lasing modes are collected in the far-field and their temporal spectral traces show characteristic lifetimes of about 2 ms. The latter values scale with the microsphere radius and are independent of the pump power in the studied range. Finite-Element Method simulations reproduce the experimental results, revealing that the thermal dynamics is dominated by the heat dissipated towards the substrate through the medium surrounding the contact point. The characteristic system scale regarding thermal transport is of few hundreds of nanometers, thus enabling an effective toy model for investigating heat conduction in non-continuum gaseous media and near-field radiative energy transfer.

  20. Modeling radiative properties of nanoscale patterned wafers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Temperature nonuniformity in rapid thermal processing of wafers is a critical problem facing the semiconductor industry. One cause of the problem is the nonuniform absorption of thermal radiation in patterned wafers where the optical properties vary across the wafer surface. This paper presents a parametric study of the radiative properties of patterned wafers, considering the effect of temperature, wavelength, and polarization. The finite-difference time-domain (FDTD) method is employed to examine the effect of various trench sizes on the radiative properties via numerically solving the Maxwell equations. The effective medium theory (EMT) is also used to help explain the absorptance prediction. The results show that in the cases with trench size variation, the resonance cavity effect may increase the absorptance as the trench width increases. And in the cases with trench size increasing at several different filling ratios, the absorptance does not change much at small filling ratio. The effects of the resonant cavity, diffraction, wave interferences on the spectral-directional absorptance were also discussed. This work is of great importance for optimization of advanced annealing techniques in semiconductor manufacturing.

  1. Far-field super-resolution imaging with a planar hyperbolic metamaterial lens beyond the Fabry-Perot resonance condition

    CERN Document Server

    Lv, Cheng; Jiang, Xunya; Cao, Juncheng

    2014-01-01

    We demonstrate achieving the far-field super-resolution imaging can be realized by using a planar hyperbolic metamaterial lens (PHML), beyond the Fabry-Perot resonance condition. Although the thickness of the PHML is much larger than wavelength, the PHML not only can transmit radiative waves and evanescent waves with high transmission, but also can collect all the waves in the image region with the amplitudes of them being the same order of magnitude. We present a design for a PHML to realize the far-field super-resolution imaging, with the distance between the sources and the images 10 times larger than wavelength. We show the superresolution of our PHML is robust against losses, and the PHML can be fabricated by periodic stacking of metal and dielectric layers.

  2. Emergence of spatiotemporal chaos arising from far-field breakup of spiral waves in the plankton ecological systems

    Institute of Scientific and Technical Information of China (English)

    Liu Quan-Xing; Sun Gui-Quan; Jin Zhen; Li Bai-Lian

    2009-01-01

    It has been reported that the minimal spatially extended phytoplankton-zooplankton system exhibits both tem-poral regular/chaotic behaviour, and spatiotemporal chaos in a patchy environment. As a further investigation by means of computer simulations and theoretical analysis, in this paper we observe that the spiral waves may exist and the spatiotcmporal chaos emerge when the parameters are within the mixed Turing Hopf bifurcation region, which arises from the far-field breakup of the spiral waves over a large range of diffusion coefficients of phytoplankton and zooplankton. Moreover, the spatiotemporal chaos arising from the far-field breakup of spiral waves does not gradually invade the whole space of that region. Our results arc confirmed by nonlinear bifurcation of wave trains. We also discuss ecological implications of these spatially structured patterns.

  3. Coherent addition of gratings for chirped-pulse-amplified lasers based on near-field and far-field measurements

    Institute of Scientific and Technical Information of China (English)

    Yuchuan Yang; Hui Luo; Xiao Wang; Fuquan Li; Xiaojun Huang; Bin Feng; Feng Jing

    2011-01-01

    @@ The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers.Almost all systems have adopted a tiled-grating approach to meet the size require-ments for the compression gratings.We present a computer-control test system utilizing near-field interfer-ence and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT)of the individual inteiference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference.Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.%The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers. Almost all systems have adopted a tiled-grating approach to meet the size requirements for the compression gratings. We present a computer-control test system utilizing near-field interference and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT)of the individual inter ference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference. Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.

  4. A FLOSS Tool for Antenna Radiation Patterns

    CERN Document Server

    Yannopoulou, Nikolitsa

    2010-01-01

    This paper briefly highlights the features of the software tool [RadPat4W], named after Radiation Patterns for Windows but also compatible with the [Wine] environment of Linux. The tool is a stand-alone part of a freeware suite that is based on an alternative exposition of fundamental Antenna Theory and is under active development for many years now. Nevertheless, [RadPat4W] source code has been now released as FLOSS Free Libre Open Source Software and thus it may be freely used, copied, modified or redistributed, individually or cooperatively, by the interested user to suit her/his personal needs for reliable antenna applications from the simplest to the more complex.

  5. A Line Integral Representation of the Physical Optics Far Field from Plane PEC Scatterers Illuminated by Electric or Magnetic Hertzian Dipoles

    DEFF Research Database (Denmark)

    Arslanagic, S.; Meincke, Peter; Jørgensen, E.;

    2002-01-01

    We derive a line integral representation of the physical optics (PO) scattered far field that yields the exact same result as the conventional surface radiation integral. This representation applies to a perfectly electrically conducting plane scatterer illuminated by electric or magnetic Hertzian...... dipoles....

  6. Energy flux density and angular momentum density of Pearcey-Gauss vortex beams in the far field

    Science.gov (United States)

    Cheng, K.; Lu, G.; Zhong, X.

    2017-02-01

    The longitudinal and transverse energy flux density (EFD) and angular momentum density (AMD) of a Pearcey-Gauss vortex beam in the far field are studied using the vector angular spectrum representation and stationary phase method, where the influence of topological charge, noncanonical strength and off-axis distance of the embedded optical vortex on far-field vectorial structures of the corresponding beam is emphasized. For comparison, the EFD and AMD of the Pearcey-Gauss beam with non-vortex in the far field are also discussed. The results show that the longitudinal EFDs of the Pearcey-Gauss vortex beam exhibit parabolic patterns, and the number of parabolic dark zones equals the absolute value of topological charge of the embedded optical vortex in the input plane. While for the Pearcey-Gauss beam, the dark zones are not found owing to the non-vortex in the input plane. The motion of zero-intensity spot of whole beam appears by varying the off-axis distance. Noncanonical strength and off-axis distance both can adjust the magnitudes and directions of transverse EFD and control the spatial energy distributions of longitudinal EFD, but not change the net AMD.

  7. J-85 jet engine noise measured in the ONERA S1 wind tunnel and extrapolated to far field

    Science.gov (United States)

    Soderman, Paul T.; Julienne, Alain; Atencio, Adolph, Jr.

    1991-01-01

    Noise from a J-85 turbojet with a conical, convergent nozzle was measured in simulated flight in the ONERA S1 Wind Tunnel. Data are presented for several flight speeds up to 130 m/sec and for radiation angles of 40 to 160 degrees relative to the upstream direction. The jet was operated with subsonic and sonic exhaust speeds. A moving microphone on a 2 m sideline was used to survey the radiated sound field in the acoustically treated, closed test section. The data were extrapolated to a 122 m sideline by means of a multiple-sideline source-location method, which was used to identify the acoustic source regions, directivity patterns, and near field effects. The source-location method is described along with its advantages and disadvantages. Results indicate that the effects of simulated flight on J-85 noise are significant. At the maximum forward speed of 130 m/sec, the peak overall sound levels in the aft quadrant were attentuated approximately 10 dB relative to sound levels of the engine operated statically. As expected, the simulated flight and static data tended to merge in the forward quadrant as the radiation angle approached 40 degrees. There is evidence that internal engine or shock noise was important in the forward quadrant. The data are compared with published predictions for flight effects on pure jet noise and internal engine noise. A new empirical prediction is presented that relates the variation of internally generated engine noise or broadband shock noise to forward speed. Measured near field noise extrapolated to far field agrees reasonably well with data from similar engines tested statically outdoors, in flyover, in a wind tunnel, and on the Bertin Aerotrain. Anomalies in the results for the forward quadrant and for angles above 140 degrees are discussed. The multiple-sideline method proved to be cumbersome in this application, and it did not resolve all of the uncertainties associated with measurements of jet noise close to the jet. The

  8. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Arindam Pal

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for 2×2 MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  9. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Pal Arindam

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  10. Simultaneous drift, microsaccades, and ocular microtremor measurement from a single noncontact far-field optical sensor

    Science.gov (United States)

    Ryle, James P.; Vohnsen, Brian; Sheridan, John T.

    2015-02-01

    We report on the combined far-field measurement of the three involuntary eye movements, drift, microsaccades, and ocular microtremor (OMT), using a noncontact far-field optical method. We review the significance of the smallest and least measured, and thus least understood, of the three, OMT. Using modern digital imaging techniques, we perform detailed analysis, present experimental results, and examine the extracted parameters using a noncontact far-field sensor. For the first time, in vivo noncontact measurements of all three fixational in-plane movements of the human eye are reported, which simultaneously provide both the horizontal (left-right) and vertical (up-down) displacement results.

  11. Development of a numerical modelling tool for combined near field and far field wave transformations using a coupling of potential flow solvers

    DEFF Research Database (Denmark)

    Verbrugghe, Tim; Troch, Peter; Kortenhaus, Andreas;

    2016-01-01

    Wave energy converters (WECs) need to be deployed in large numbers in an array layout in order to have a significant power production. Each WEC has an impact on the incoming wave field, diffracting, reflecting and radiating waves. Simulating the wave transformations within and around a WEC farm...... is complex; it is difficult to simulate both near field and far field effects with a single numerical model, with relatively fast computing times. Within this research a numerical tool is developed to model near-field and far-field wave transformations caused by WECs. The tool is based on the coupling...... that the coupling of the two solvers is an efficient and promising numerical tool to perform simulations on near – and far field wave elevations and kinematics nearby WEC farms....

  12. Structural polarization properties of vector Gaussian beam in the far field

    Institute of Scientific and Technical Information of China (English)

    Zhou Guo-Quan; Ni Yong-Zhou; Chu Xiu-Xiang

    2007-01-01

    Based on the vector angular spectrum representation of optical beam and the method of stationary phase, the analytical TE and TM terms of vector Gaussian beam have been presented in the far field. By using the local polarization matrix, the polarization properties of the TE and TM terms in the far field are investigated, and it is found that the degree of their polarization is only determined by the spatial location. When the source is completely polarized, the TE and TM terms are both completely polarized in the far field. When the source is completely unpolarized, the TE and TM terms in the far field are partially polarized. The whole beam is also partially polarized except on the propagating axis. Moreover, the degrees of polarization of TE and TM terms are both larger than that of the whole beam.

  13. Certified dual-corrected radiation patterns of phased antenna arrays by offline–online order reduction of finite-element models

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, A., E-mail: a.sommer@lte.uni-saarland.de; Farle, O., E-mail: o.farle@lte.uni-saarland.de; Dyczij-Edlinger, R., E-mail: edlinger@lte.uni-saarland.de

    2015-10-15

    This paper presents a fast numerical method for computing certified far-field patterns of phased antenna arrays over broad frequency bands as well as wide ranges of steering and look angles. The proposed scheme combines finite-element analysis, dual-corrected model-order reduction, and empirical interpolation. To assure the reliability of the results, improved a posteriori error bounds for the radiated power and directive gain are derived. Both the reduced-order model and the error-bounds algorithm feature offline–online decomposition. A real-world example is provided to demonstrate the efficiency and accuracy of the suggested approach.

  14. One-dimensional Fibonacci grating for far-field super-resolution imaging.

    Science.gov (United States)

    Wu, Kedi; Wang, Guo Ping

    2013-06-15

    One-dimensional Fibonacci gratings are used to transform evanescent waves into propagating waves for far-field super-resolution imaging. By detecting far-field intensity distributions of light through objects in front of the Fibonacci grating in free space, we can observe the objects with nearly λ/9 spatial resolution. Analytical results are verified by numerical simulations. We also discuss the effect of sampling error on imaging resolution of the system.

  15. Steering far-field spin-dependent splitting of light by inhomogeneous anisotropic media

    CERN Document Server

    Ling, Xiaohui; Luo, Hailu; Wen, Shuangchun

    2012-01-01

    An inhomogeneous anisotropic medium with specific structure geometry can apply tunable spin-dependent geometrical phase to the light passing through the medium, and thus can be used to steer the spin-dependent splitting (SDS) of light. In this paper, we exemplify this inference by the $q$-plate, an inhomogeneous anisotropic medium. It is demonstrated that when a linearly polarized light beam normally passes through a $q$-plate, $k$-space SDS first occurs, and then the real-space SDS in the far-field focal plane of a converging lens is distinguishable. Interestingly, the SDS, described by the normalized Stokes parameter $S_3$, shows a multi-lobe and rotatable splitting pattern with rotational symmetry. Further, by tailoring the structure geometry of $q$-plate or/and incident polarization angle of light, the lobe number and the rotation angle both are tunable. Our result suggests that the $q$-plate can serve as potential devices for manipulating the photon spin states and enable applications such as in nano-opt...

  16. Far-field coseismic displacements associated with the great Sumatra earthquakes of December 26, 2004 and March 29, 2005 constrained by Global Positioning System

    Institute of Scientific and Technical Information of China (English)

    WANG Min; ZHANG Peizhen; SHEN Zhengkang; LIU Jie; SUN Hanrong; GAN Weijun; LI Peng

    2006-01-01

    Based on continuous GPS observations within China as well as global GPS tracking network,a calculation has been made of far-field coseismic displacements associated with the December, 2004 (Mw= 9.3) and March, 2005 (Mw= 8.7) earthquakes.The far-field coseismic displacements are associated with the 2004 shock range more than 6000-7000 krn in both north-south and east-west dimensions,and depict an undulated wave pattern of contraction and extension. The coseismic displacements associated with the 2005 event, however, are distributed near the epicentral region, and the event itself may be an aftershock of the 2004 earthquake.

  17. Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rhinefrank, Kenneth E; Haller, Merrick C; Ozkan-Haller, H Tuba

    2013-01-26

    This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed Buoys' that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate

  18. Far Field Extrapolation from Near Field Interactions and Shielding Influence Investigations Based on a FE-PEEC Coupling Method

    Directory of Open Access Journals (Sweden)

    Gérard Meunier

    2013-03-01

    Full Text Available Regarding standards, it is well established that common mode currents are the main source of far field emitted by variable frequency drive (VFD-cable-motor associations. These currents are generated by the combination of floating potentials with stray capacitances between these floating potential tracks and the mechanical parts connected to the earth (the heatsink or cables are usual examples. Nowadays, due to frequency and power increases, the systematic compliance to EMC (ElectroMagnetic Compatibility becomes increasingly difficult and costly for industrials. As a consequence, there is a well-identified need to investigate practical and low cost solutions to reduce the radiated fields of VFD-cable-motor associations. A well-adapted solution is the shielding of wound components well known as the major source of near magnetic field. However, this solution is not convenient, it is expensive and may not be efficient regarding far field reduction. Optimizing the components placement could be a better and cheaper solution. As a consequence, dedicated tools have to be developed to efficiently investigate not easy comprehendible phenomena and finally to control EMC disturbances using component placement, layout geometry, shielding design if needed. However, none of the modeling methods usually used in industry complies with large frequency range and far field models including magnetic materials, multilayer PCBs, and shielding. The contribution of this paper is to show that alternatives regarding modeling solutions exist and can be used to get in-deep analysis of such complex structures. It is shown in this paper that near field investigations can give information on far field behavior. It is illustrated by an investigation of near field interactions and shielding influence using a FE-PEEC hybrid method. The test case combining a common mode filter with the floating potentials tracks of an inverter is based on an industrial and commercialized VFD. The

  19. The extraordinary radiation pattern of an optical rod antenna

    CERN Document Server

    Zhao, Chenglong

    2010-01-01

    We investigated the radiation pattern of an optical rod antenna and found that it had many features compared with its conventional radio-wave equivalents. After defining a parameter {\\Lambda} = {\\lambda}eff /{\\lambda}, which was the ratio of the effective wavelength of the rod antenna to the incident wavelength, we found that {\\Lambda} had a great influence on the radiation pattern. Even the radiation pattern with a higher resonant order is without side lobes and results in a sharper directivity, which provides new design flexibilities in improving the directivities of the optical antennas.

  20. Two-dimensional Fibonacci grating for far-field super-resolution imaging

    Science.gov (United States)

    Wu, Kedi; Wang, Guo Ping

    2016-12-01

    A two-dimensional (2D) Fibonacci grating is used to transform evanescent waves into propagating waves for far-field super-resolution imaging. By detecting far-field intensity distributions of light field through objects in front of the 2D Fibonacci grating in free space at once, we can retrieve the image of objects with beyond λ/7 spatial resolution. We also find that the coherent illumination case can give a better resolution than incoherent illumination case by such 2D grating-assisted imaging system. The analytical results are verified by numerical simulation.

  1. Analysis of ventilation systems subjected to explosive transients: far-field analysis

    Energy Technology Data Exchange (ETDEWEB)

    Tang, P.K.; Andrae, R.W.; Bolstad, J.W.; Duerre, K.H.; Gregory, W.S.

    1981-11-01

    Progress in developing a far-field explosion simulation computer code is outlined. The term far-field implies that this computer code is suitable for modeling explosive transients in ventilation systems that are far removed from the explosive event and are rather insensitive to the particular characteristics of the explosive event. This type of analysis is useful when little detailed information is available and the explosive event is described parametrically. The code retains all the features of the TVENT code and allows completely compressible flow with inertia and choking effects. Problems that illustrate the capabilities and limitations of the code are described.

  2. Research on Far-Field Wavelet's Extraction and Application of Vertical Cable System

    Science.gov (United States)

    Wang, Xiangchun; Xiao, Qingsong; Xia, Changliang; Wu, Zhongliang; Xie, Chengliang

    2017-03-01

    In marine seismic exploration, ghost wave and bubble effect reduce the vertical resolution and interpretation accuracy seriously. Here firstly the far-field wavelet including source wavelet, ghost wave and bubble effect recorded by the vertical cable system (VCS) is extracted. Then, filters are designed using the extracted far-field wavelet to eliminate ghost wave, bubble effect and source wavelet. At last, the designed filters are applied to the seismic data of VCS. The results show that this method can eliminate ghost wave, bubble effect and source wavelet effectively and the vertical resolution of the seismic data is improved obviously.

  3. Numerical Methods for the Nonlinear Schrödinger Equation with Nonzero Far-field Conditions

    OpenAIRE

    2004-01-01

    In this paper we present numerical methods for the nonlinear Schrödinger equations (NLS) in the semiclassical regimes: \\[i \\vep\\; u_t^\\vep=-\\fl{\\vep^2}{2}\\;\\btu u^\\vep+V(\\bx)u^\\vep+ f(|u^\\vep|^2)u^\\vep, \\qquad \\bx\\in{\\Bbb R}^d,\\] with nonzero far-field conditions. A time-splitting cosine-spectral (TS-Cosine) method is presented when the nonzero far-field conditions are or can be reduced to homogeneous Neumann conditions, a time-splitting Chebyshev-spectral (TS-Chebyshe...

  4. Compact representation of radiation patterns using spherical mode expansions

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, T.L.; Chen, Yinchao (South Carolina Univ., Columbia, SC (USA). Dept. of Electrical and Computer Engineering)

    1990-07-15

    This report presents the results of an investigation of SM (Spherical Mode) expansions as a compact and efficient alternative to the use of current distributions for generating radiation patterns. The study included three areas: (1) SM expansion from the radiation pattern; (2) SM expansion from the antenna current; and (3) Literature search. SM expansions were obtained from radiation patterns during the initial phase of this study. Although straightforward in principal, however, this technique was found to be awkward for the treatment on theoretical radiation patterns. It is included here for completeness and for possible use to summarize experimental results in a more meaningful way than with an exhaustive display of amplitude with azimuth and elevation angles. In essence, the work in this area served as as warm-up problem to develop our skills in computing and manipulating spherical modes as mathematical entities. 6 refs., 21 figs., 6 tabs.

  5. Calculation of patterns of solar radiation within urban geometries

    OpenAIRE

    Carrasco Hernandez, Roberto

    2015-01-01

    ABSTRACTThe University of ManchesterRoberto Carrasco-Hernandez. PhD in Earth Atmospheric and Environmental Sciences.Calculation of patterns of solar radiation within urban geometries.30 May 2015The present work proposes methods to calculate street-level exposures to solar radiation. The methods comprise a combination of different software algorithms, online databases and real-time standard measurements of solar radiation. Firstly, the use of the free access image database “Google Street View”...

  6. Demonstration of a white beam far-field neutron interferometer for spatially resolved small angle neutron scattering

    CERN Document Server

    Hussey, Daniel S; Yuan, Guangcui; Pushin, Dmitry; Sarenac, Dusan; Huber, Michael G; Jacobson, David L; LaManna, Jacob M; Wen, Han

    2016-01-01

    We provide the first demonstration that a neutron far-field interferometer can be employed to measure the microstructure of a sample. The interferometer is based on the moir\\'e pattern of two phase modulating gratings which was previously realized in hard x-ray and visible light experiments. The autocorrelation length of this interferometer, and hence the microstructure length scale that is probed, is proportional to the grating spacing and the neutron wavelength, and can be varied over several orders of magnitude for one pair of gratings. We compare our measurements of the change in visibility from monodisperse samples with calculations which show reasonable agreement. The potential advantages of a far-field neutron interferometer include high fringe visibility in a polychromatic beam (over 30 %), no requirement for an absorbing grating to resolve the interference fringes, and the ability to measure the microstructure in the length scale range of 100 nm to 10 \\mum by varying either the grating spacing or neu...

  7. Comparison of different antenna diagnostics techniques with limited far field data input

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Cappellin, Cecilia

    2015-01-01

    In this paper, three different antenna diagnostics techniques are compared for the case when the input far-field data represent only few complete cuts or a two-dimensional grid with a limited angular sector. The techniques are applied to several different antennas: a high-gain offset reflector...... and extreme near fields....

  8. Analysis of atrial sensed far-field ventricular signals : A reassessment

    NARCIS (Netherlands)

    Brouwer, J; Nagelkerke, D; denHeijer, P; Mulder, H; Begemann, MJS; Lie, KI; Ruiter, Jaap H.

    1997-01-01

    Accurate detection of the spontaneous far-field ventricular signal may be used to determine the ventricular activation, and hence, the interval from atrial stimulus to the ventricular R wave (AR interval) using a standard atrial pacing lead. This can be useful in developing a physiological atrial ra

  9. Second-order spatial correlation in the far-field: Comparing entangled and classical light sources

    Science.gov (United States)

    Zhang, Erfeng; Liu, Weitao; Lin, Huizu; Chen, Pingxing

    2016-02-01

    We consider second-order spatial correlation with entangled and classical light in the far-field. The quantum theory of second-order spatial correlation is analyzed, and the role of photon statistics and detection mode in the second-order spatial correlation are discussed. Meanwhile, the difference of second-order spatial correlation with entangled and classical light sources is deduced.

  10. Anomalous spectral shift of near- and far-field plasmonic resonances in nano-gaps

    CERN Document Server

    Lombardi, Anna; Weller, Lee; Andrae, Patrick; Benz, Felix; Chikkaraddy, Rohit; Aizpurua, Javier; Baumberg, Jeremy J

    2016-01-01

    The near-field and far-field spectral response of plasmonic systems are often assumed to be identical, due to the lack of methods that can directly compare and correlate both responses under similar environmental conditions. We develop a widely-tuneable optical technique to probe the near-field resonances within individual plasmonic nanostructures that can be directly compared to the corresponding far-field response. In tightly-coupled nanoparticle-on-mirror constructs with nanometer-sized gaps we find >40meV blueshifts of the near-field compared to the dark-field scattering peak, which agrees with full electromagnetic simulations. Using a transformation optics approach, we show such shifts arise from the different spectral interference between different gap modes in the near- and far-field. The control and tuning of near-field and far-field responses demonstrated here is of paramount importance in the design of optical nanostructures for field-enhanced spectroscopy, as well as to control near-field activity ...

  11. Far-field DOA estimation and near-field localization for multipath signals

    Science.gov (United States)

    Elbir, Ahmet M.; Tuncer, T. Engin

    2014-09-01

    In direction finding and localization applications, multipath signals are important sources of error for parameter estimation. When the antenna array receives multipath reflections which are coherent with the far-field line-of-sight signal, estimating the far- and near-field components becomes an important problem. In this paper, a new method is proposed to estimate the direction-of-arrival (DOA) of the far-field source and to localize its near-field multipaths. Far-field source DOA is estimated using calibration of the antenna array. A near-to-far transformation is proposed for the estimation of the near-field source DOA angles. In order to estimate the near-field range parameters, a compressive sensing approach is presented where a dictionary with near-field sources with different ranges is employed. As a result, the proposed method estimates the far-field and near-field source DOAs as well as the range and the signal amplitudes of the near-field sources. This method is evaluated using close-to-real world data generated by a numerical electromagnetic tool, where the array and transmitter are placed in an irregular terrain and array data are generated using full 3-D propagation model. It is shown that unknown source parameters can be estimated effectively showing the potential of the proposed approach in applications involving high-frequency direction finding and indoor localization.

  12. 14 CFR 417.229 - Far-field overpressure blast effects analysis.

    Science.gov (United States)

    2010-01-01

    ... to potential explosions during launch vehicle flight and demonstrate compliance with the public risk... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.229 Far-field overpressure blast effects analysis. (a) General. A flight safety analysis must establish flight commit...

  13. Approach to tune near- and far-field properties of hybrid dimer nanoantennas via laser melting at the nanoscale

    CERN Document Server

    Sun, Yali; Zuev, Dmitry; Huang, Lirong; Krasnok, Alexander; Belov, Pavel

    2016-01-01

    Asymmetric metal-dielectric nanostructures are demonstrated superior optical properties arise from the combination of strong enhancement of their near fields and controllable scattering characteristics which originate from plasmonic and high-index dielectric components. Here, being inspired by the recent experimental work [Dmitry~Zuev, \\textit{et al.}, Adv. Mater. \\textbf{28}, 3087 (2016)] on a new technique for fabrication of asymmetric hybrid nanoparticles via femtosecond laser melting at the nanoscale, we suggest and study numerically a novel type of hybrid dimer nanoantennas. The nanoantennas consist of asymmetric metal-dielectric (Au/Si) nanoparticles and can allow tuning of the near- and far-field properties via laser melting of the metal part. We demonstrate a modification of scattering properties, near electric field distribution, normalized local density of states, and power patters of radiation of the nanoantennas upon laser reshaping. The parameters used to investigate these effects correspond to e...

  14. An improved schlieren method for measurement and automatic reconstruction of the far-field focal spot

    Science.gov (United States)

    Wang, Zhengzhou; Hu, Bingliang; Yin, Qinye

    2017-01-01

    The schlieren method of measuring far-field focal spots offers many advantages at the Shenguang III laser facility such as low cost and automatic laser-path collimation. However, current methods of far-field focal spot measurement often suffer from low precision and efficiency when the final focal spot is merged manually, thereby reducing the accuracy of reconstruction. In this paper, we introduce an improved schlieren method to construct the high dynamic-range image of far-field focal spots and improve the reconstruction accuracy and efficiency. First, a detection method based on weak light beam sampling and magnification imaging was designed; images of the main and side lobes of the focused laser irradiance in the far field were obtained using two scientific CCD cameras. Second, using a self-correlation template matching algorithm, a circle the same size as the schlieren ball was dug from the main lobe cutting image and used to change the relative region of the main lobe cutting image within a 100×100 pixel region. The position that had the largest correlation coefficient between the side lobe cutting image and the main lobe cutting image when a circle was dug was identified as the best matching point. Finally, the least squares method was used to fit the center of the side lobe schlieren small ball, and the error was less than 1 pixel. The experimental results show that this method enables the accurate, high-dynamic-range measurement of a far-field focal spot and automatic image reconstruction. Because the best matching point is obtained through image processing rather than traditional reconstruction methods based on manual splicing, this method is less sensitive to the efficiency of focal-spot reconstruction and thus offers better experimental precision. PMID:28207758

  15. Far-field momentum flux of high-frequency axisymmetric synthetic jets

    Science.gov (United States)

    Xia, X.; Mohseni, K.

    2015-11-01

    This study focuses on predicting the far-field momentum flux for axisymmetric synthetic jets, which is an important parameter that characterizes the performance of such jets in flow-control applications. Previous researchers have found that a negative pressure gradient near the jet orifice is responsible for the observed decrease in the momentum flux in the streamwise direction. As a result, prediction of the far field momentum flux of synthetic jets has encountered serious challenges. In this paper, the far-field momentum flux is modeled by calculating the hydrodynamic impulse of the vortical structure formed during one actuation cycle, under the assumption that the jet is fully developed and periodic. In this manner, the complex near-field effect of a synthetic jet is explicitly captured by the interactions between the vortices and the actuator. Furthermore, the impulse of these vortical structures is predicted using only the actuation parameters of the synthetic jet, namely, the stroke length, L, the orifice diameter, d, and the actuation frequency, f. For a synthetic jet with a stroke ratio, L/d, larger than the formation number, L∗/d, this model predicts that the normalized far-field momentum flux, K/Ks, decreases when L/d increases. This can be explained by an increasing circulation fraction of the trailing jet, which contains less impulse per unit circulation compared with the leading vortex. This model is validated using hot-wire anemometry measurement of a series of synthetic jets. Moreover, by comparing with experimental data that have large L/d, this model suggests that the contribution of trailing jet to the overall far-field momentum flux is not negligible.

  16. Using submicron-resolution LiF crystal and film x-ray detectors for the near and far fields in-situ characterization of soft x-ray laser beams

    Science.gov (United States)

    Pikuz, Tatiana A.; Faenov, Anatoly Y.; Fukuda, Yuji; Kato, Yoshiaki; Kawachi, Tetsuya; Kando, Masaki

    2012-01-01

    Review of results, obtained by using recently proposed new imaging detector, based on formation of color centers in LiF crystal and LiF film, for in situ high performance measurements of near-field and far-field properties of soft X-ray lasers (SXRL) beams is presented. Experiments have been carried out with laser-driven transient-collision plasma SXRL and free electron SXRL beams. It was demonstrated that due to favorable combination of high spatial resolution, high dynamic range and wide field of view this technique allows measuring not only intensity distribution across the full beam and in local areas, but also permits to evaluate coherence and spectral distribution of radiation across the beam. Experimental diffraction patterns in the images of periodical structures are analyzed by comparison with the modeled ones in the last case. The estimated accuracy of measurements is between 10-20%.

  17. Radiation regression patterns after cobalt plaque insertion for retinoblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Buys, R.J.; Abramson, D.H.; Ellsworth, R.M.; Haik, B.

    1983-08-01

    An analysis of 31 eyes of 30 patients who had been treated with cobalt plaques for retinoblastoma disclosed that a type I radiation regression pattern developed in 15 patients; type II, in one patient, and type III, in five patients. Nine patients had a regression pattern characterized by complete destruction of the tumor, the surrounding choroid, and all of the vessels in the area into which the plaque was inserted. This resulting white scar, corresponding to the sclerae only, was classified as a type IV radiation regression pattern. There was no evidence of tumor recurrence in patients with type IV regression patterns, with an average follow-up of 6.5 years, after receiving cobalt plaque therapy. Twenty-nine of these 30 patients had been unsuccessfully treated with at least one other modality (ie, light coagulation, cryotherapy, external beam radiation, or chemotherapy).

  18. Far-field mapping of the longitudinal magnetic and electric optical fields

    CERN Document Server

    Ecoffey, C

    2013-01-01

    In this letter, we demonstrate the experimental mapping of the longitudinal magnetic and electric optical fields with a standard scanning microscope that involves a high numerical aperture far-field objective. The imaging concept relies upon the insertion of an azimuthal or a radial polarizer within the detection path of the microscope which acts as an optical electromagnetic filter aimed at transmitting selectively to the detector the signal from the magnetic or electric longitudinal fields present in the detection volume, respectively. The resulting system is thus versatile, non invasive, of high resolution, and shows high detection efficiencies. Magnetic optical properties of physical and biological micro and nano-structures may thus be revealed with a far-field microscope.

  19. Second-order spatial correlation in the far-field: Comparing entangled and classical light sources

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Erfeng, E-mail: efzhang@163.com; Liu, Weitao; Lin, Huizu; Chen, Pingxing

    2016-02-15

    Highlights: • Second-order spatial correlation with entangled and classical light in the far-field is investigated. • The role of photon statistics and detection mode in the second-order spatial correlation are discussed. • The difference of second-order spatial correlation with entangled and classical light sources is deduced. - Abstract: We consider second-order spatial correlation with entangled and classical light in the far-field. The quantum theory of second-order spatial correlation is analyzed, and the role of photon statistics and detection mode in the second-order spatial correlation are discussed. Meanwhile, the difference of second-order spatial correlation with entangled and classical light sources is deduced.

  20. Far Field Evolution of Momentum Driven and Scalar Dominated Flow Field

    Directory of Open Access Journals (Sweden)

    V. Ilangovan

    2016-01-01

    Full Text Available To capture the effect of initial conditions in far field evolution of momentum driven and scalar dominated flow field, Witze scaling has been used for collapsing vector and scalar data to attain asymptotic state at self-preserving region of the jet. It incorporates the initial mass, momentum, energy to capture the effect of heating level on both near and far field development of strongly heated coaxial turbulent round air jets entering into quiescent ambient. This paper compares the effectiveness of potential core length and jet effective diameter as the length scales to collapse both mean and fluctuating components of velocity vector and temperature scalar. Similarity considerations with Witze length scale using the initial momentum flux and buoyancy flux gives a good collapse at all levels of heating.

  1. Far-field subwavelength imaging from a single broadband antenna in combined with strongly disordered medium

    CERN Document Server

    Li, Lianlin; Cui, Tie Jun

    2014-01-01

    The far-field subwavlength imaging is a challenging issue. In this letter we demonstrate numerically that the far-field subwavelength imaging of weakly scattering objects can be obtained by processing the data acquired by a single antenna, which benefits from the use of the strongly disordered medium. A mathematical model has been proposed for solving such problem based on the idea of sparse reconstruction. Moreover, this study leads to an important conclusion that the strongly disordered medium can serves as an efficient apparatus for the single-antenna compressive measurement, which shifts the complexity of devising compressive sensing (CS) hardware from the design, fabrication and electronic control. The proposed method and associated results can find applications in several imaging disciplines, such as optics, THz, RF or ultrasound imaging.

  2. Far-field dispersal modeling for fuel-air-explosive devices

    Energy Technology Data Exchange (ETDEWEB)

    Glass, M.W.

    1990-05-01

    A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.

  3. Seismic Waves Scattering Impact through Tunnel Excavation on Adjacent Monuments Subjected to Far Field Earthquakes

    Directory of Open Access Journals (Sweden)

    Ghobakhloo E.

    2015-09-01

    Full Text Available The study of the effect of seismic wave scattering has attracted extensive attention in the past couple of decades especially in infrastructures like tunnels. A seismic wave, meeting the tunnel, can generate scattering which, in most cases, may incur damages in adjacent structures. In this study, using Finite Element Method (FEM, the effect of seismic wave scattering in far field has been investigated. The twin tunnels of Shiraz subway system are selected as the case study in this research and three far field seismic waves were chosen for time history analyses. Investigating the normal mode (before tunnel construction in comparison to the excavation mode (after tunnel construction enables calculation of the effect of displacement in adjacent structures. The analysis results indicate there is a significant difference between before and after tunnel construction (P-value<0.05. Accordingly, the influence of constructing a tunnel on adjacent surface structures is very important for tunnel design.

  4. Far-Field Turbulent Vortex-Wake/Exhaust Plume Interaction for Subsonic and HSCT Airplanes

    Science.gov (United States)

    Kandil, Osama A.; Adam, Ihab; Wong, Tin-Chee

    1996-01-01

    Computational study of the far-field turbulent vortex-wake/exhaust plume interaction for subsonic and high speed civil transport (HSCT) airplanes is carried out. The Reynolds-averaged Navier-Stokes (NS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The two-equation shear stress transport model of Menter is implemented with the NS solver for turbulent-flow calculation. For the far-field study, the computations of vortex-wake interaction with the exhaust plume of a single engine of a Boeing 727 wing in a holding condition and two engines of an HSCT in a cruise condition are carried out using overlapping zonal method for several miles downstream. These results are obtained using the computer code FTNS3D. The results of the subsonic flow of this code are compared with those of a parabolized NS solver known as the UNIWAKE code.

  5. A far-field-viewing sensor for making analytical measurements in remote locations.

    Science.gov (United States)

    Michael, K L; Taylor, L C; Walt, D R

    1999-07-15

    We demonstrate a far-field-viewing GRINscope sensor for making analytical measurements in remote locations. The GRINscope was fabricated by permanently affixing a micro-Gradient index (GRIN) lens on the distal face of a 350-micron-diameter optical imaging fiber. The GRINscope can obtain both chemical and visual information. In one application, a thin, pH-sensitive polymer layer was immobilized on the distal end of the GRINscope. The ability of the GRINscope to visually image its far-field surroundings and concurrently detect pH changes in a flowing stream was demonstrated. In a different application, the GRINscope was used to image pH- and O2-sensitive particles on a remote substrate and simultaneously measure their fluorescence intensity in response to pH or pO2 changes.

  6. Multi-pulse pumping for far-field super-resolution imaging

    Science.gov (United States)

    Requena, Sebastian; Raut, Sangram; Doan, Hung; Kimball, Joe; Fudala, Rafal; Borejdo, Julian; Gryczynski, Ignacy; Strzhemechny, Yuri; Gryczynski, Zygmunt

    2016-02-01

    Recently, far-field optical imaging with a resolution significantly beyond diffraction limit has attracted tremendous attention allowing for high resolution imaging in living objects. Various methods have been proposed that are divided in to two basic approaches; deterministic super-resolution like STED or RESOLFT and stochastic super-resolution like PALM or STORM. We propose to achieve super-resolution in far-field fluorescence imaging by the use of controllable (on-demand) bursts of pulses that can change the fluorescence signal of long-lived component over one order of magnitude. We demonstrate that two beads, one labeled with a long-lived dye and another with a short-lived dye, separated by a distance lower than 100 nm can be easily resolved in a single experiment. The proposed method can be used to separate two biological structures in a cell by targeting them with two antibodies labeled with long-lived and short-lived fluorophores.

  7. Examination of Far-Field Mathematical Absorber Reflection Suppression through Computational Electromagnetic Simulation

    Directory of Open Access Journals (Sweden)

    S. F. Gregson

    2012-01-01

    Full Text Available The mathematical absorber reflection suppression (MARS technique has been used to identify and then suppress the effects of spurious scattering within spherical, cylindrical, and planar near-field antenna measurement systems, compact antenna test ranges (CATRs, and far-field measurement facilities for some time now. The recent development of a general-purpose three-dimensional computational electromagnetic model of a spherical antenna test system has enabled the MARS measurement and postprocessing technique to be further investigated. This paper provides an overview of the far-field MARS technique and presents an introduction to the computational electromagnetic range model. Preliminary results of computational electromagnetic range simulations that replicate typical MARS measurement configurations are presented and discussed which, for the first time, confirm through simulation many of the observations that have previously been noted using purely empirical techniques.

  8. Near-Field/Far-Field Transformation with Helicoidal Scanning from Irregularly Spaced Data

    Directory of Open Access Journals (Sweden)

    Francesco D'Agostino

    2010-01-01

    Full Text Available A fast and accurate technique for the compensation of the probe positioning errors in the near-field/far-field transformation with helicoidal scanning is proposed in this paper. It relies on a nonredundant sampling representation using a spherical modelling of the antenna under test and employs an iterative scheme to evaluate the near-field data at the points fixed by the helicoidal nonredundant representation from the acquired irregularly distributed ones. Once these helicoidal data have been recovered, those required by a classical cylindrical near-field/far-field transformation are efficiently determined by using an optimal sampling interpolation algorithm. Some numerical tests assessing the effectiveness of the proposed approach and its stability with respect to random errors affecting the near-field data are shown.

  9. Concept of far-field optical evaluation of the apparatus function of an SNOM tip

    Science.gov (United States)

    Voznesensky, Nikolay B.; Veiko, Vadim P.; Ivanova, Tatiana V.; Lee, Kyeong-Hee

    2004-04-01

    An approach to the optical investigation of probes for scanning near-field optical microscopes (SNOM tips) and recognition of their near-field parameters by far-field measurements is considered. The comparison of approximate calculations of vector light field diffracted by a subwavelength aperture with more rigorous calculations of the light field passing through a tapered end of a SNOM tip is presented. A numerical iterative procedure of the SNOM tip aperture reconstruction by the analytical continuation of the emerging light Fourier spectrum is presented. The approach is based on the use of plane waves covering a wide range of spatial frequencies. The results of experimental measurements and far-field data treatment with the definition of a subwavelength aperture are discussed.

  10. A Coupled Far-Field Formulation for Time-Periodic Numerical Problems in Fluid Dynamics

    Indian Academy of Sciences (India)

    Edmund Chadwick; Rabea El-Mazuzi

    2012-11-01

    Consider uniform flow past an oscillating body generating a time-periodic motion in an exterior domain, modelled by a numerical fluid dynamics solver in the near field around the body. A far-field formulation, based on the Oseen equations, is presented for coupling onto this domain thereby enabling the whole space to be modelled. In particular, examples for formulations by boundary elements and infinite elements are described.

  11. Optical far-field super-resolution microscopy using nitrogen vacancy center ensemble in bulk diamond

    OpenAIRE

    Li, Shen; Chen, Xiang-Dong; Zhao, Bo-Wen; Dong, Yang; Zou, Chong-Wen; Guo, Guang-Can; Sun, Fang-Wen

    2016-01-01

    We demonstrate an optical far-field super-resolution microscopy using array of nitrogen vacancy centers in bulk diamond as near-field optical probes. The local optical field, which transmits through the nanostructures on the diamond surface, is measured by detecting the charge state conversion of nitrogen vacancy center. And the locating of nitrogen vacancy center with spatial resolution of 6.1 nm is realized with the charge state depletion nanoscopy. The nanostructures on the surface of diam...

  12. Note on the classification of super-resolution in far-field microscopy and information theory

    CERN Document Server

    Passon, Oliver

    2016-01-01

    In recent years several far-field microscopy techniques have been developed which manage to overcome the diffraction limit of resolution. A unifying classification scheme for them is clearly desirable. We argue that existing schemes based on the information capacity of the optical system can not easily be extended to cover e.g., STED microscopy or techniques based on single molecule imaging. We suggest a classification based on a reconstruction of the Abbe limit.

  13. A Conformal Mapping Suitable for Problems Involving Interaction Between Given Geometries and Known Far Fields.

    Science.gov (United States)

    1984-09-01

    A conformal transformation formula using Riemann-Stieltjes integrals is derived for use with problems involving the interaction between a given finite-sized geometry and a known far field. The derivative of this transformation is non-singular in the domain considered and tends to one at infinity. A formula is derived for transformation from the unit circle to the exterior of an arbitrarily given continuous curve with bounded variation . A special case of the transformation is very similar

  14. Note on the classification of super-resolution in far-field microscopy and information theory

    Science.gov (United States)

    Passon, Oliver; Grebe-Ellis, Johannes

    2016-07-01

    In recent years several far-field microscopy techniques have been developed which manage to overcome the diffraction limit of resolution. A unifying classification scheme for them is clearly desirable. We argue that existing schemes based on the information capacity of the optical system can not easily be extended to cover e.g., STED microscopy or techniques based on single molecule imaging. We suggest a classification based on a reconstruction of the Abbe limit.

  15. Seismic Waves Scattering Impact through Tunnel Excavation on Adjacent Monuments Subjected to Far Field Earthquakes

    OpenAIRE

    Ghobakhloo E.; Pourlak M.; Razmkhah A.

    2015-01-01

    The study of the effect of seismic wave scattering has attracted extensive attention in the past couple of decades especially in infrastructures like tunnels. A seismic wave, meeting the tunnel, can generate scattering which, in most cases, may incur damages in adjacent structures. In this study, using Finite Element Method (FEM), the effect of seismic wave scattering in far field has been investigated. The twin tunnels of Shiraz subway system are selected as the case study in this research a...

  16. Two-Dimensional Far Field Source Locating Method with Nonprior Velocity

    Directory of Open Access Journals (Sweden)

    Qing Chen

    2016-01-01

    Full Text Available Relative position of seismic source and sensors has great influence on locating accuracy, particularly in far field conditions, and the accuracy will decrease seriously due to limited calculation precision and prior velocity error. In order to improve the locating accuracy of far field sources by isometric placed sensors in a straight line, a new locating method with nonprior velocity is proposed. After exhaustive research, this paper states that the hyperbola which is used for locating will be very close to its asymptote when seismic source locates in far field of sensors; therefore, the locating problem with prior velocity is equivalent to solving linear equations and the problem with nonprior velocity is equivalent to a nonlinear optimization problem with respect to the unknown velocity. And then, this paper proposed a new locating method based on a one-variable objective function with respect to the unknown velocity. Numerical experiments show that the proposed method has faster convergence speed, higher accuracy, and better stability.

  17. Far-field optical imaging with subdiffraction resolution enabled by nonlinear saturation absorption

    Science.gov (United States)

    Ding, Chenliang; Wei, Jingsong

    2016-01-01

    The resolution of far-field optical imaging is required to improve beyond the Abbe limit to the subdiffraction or even the nanoscale. In this work, inspired by scanning electronic microscopy (SEM) imaging, in which carbon (or Au) thin films are usually required to be coated on the sample surface before imaging to remove the charging effect while imaging by electrons. We propose a saturation-absorption-induced far-field super-resolution optical imaging method (SAI-SRIM). In the SAI-SRIM, the carbon (or Au) layers in SEM imaging are replaced by nonlinear-saturation-absorption (NSA) thin films, which are directly coated onto the sample surfaces using advanced thin film deposition techniques. The surface fluctuant morphologies are replicated to the NSA thin films, accordingly. The coated sample surfaces are then imaged using conventional laser scanning microscopy. Consequently, the imaging resolution is greatly improved, and subdiffraction-resolved optical images are obtained theoretically and experimentally. The SAI-SRIM provides an effective and easy way to achieve far-field super-resolution optical imaging for sample surfaces with geometric fluctuant morphology characteristics.

  18. The spectral shift between near- and far-field resonances of optical nano-antennas.

    Science.gov (United States)

    Menzel, Christoph; Hebestreit, Erik; Mühlig, Stefan; Rockstuhl, Carsten; Burger, Sven; Lederer, Falk; Pertsch, Thomas

    2014-04-21

    Within the past several years a tremendous progress regarding optical nano-antennas could be witnessed. It is one purpose of optical nano-antennas to resonantly enhance light-matter interactions at the nanoscale, e.g. the interaction of an external illumination with molecules. In this specific, but in almost all schemes that take advantage of resonantly enhanced electromagnetic fields in the vicinity of nano-antennas, the precise knowledge of the spectral position of resonances is of paramount importance to fully exploit their beneficial effects. Thus far, however, many nano-antennas were only optimized with respect to their far-field characteristics, i.e. in terms of their scattering or extinction cross sections. Although being an emerging feature in many numerical simulations, it was only recently fully appreciated that there exists a subtle but very important difference in the spectral position of resonances in the near-and the far-field. With the purpose to quantify this shift, Zuloaga et al. suggested a Lorentzian model to estimate the resonance shift. Here, we devise on fully analytical grounds a strategy to predict the resonance in the near-field directly from that in the far-field and disclose that the issue is involved and multifaceted, in general. We outline the limitations of our theory if more sophisticated optical nano-antennas are considered where higher order multipolar contributions and higher order antenna resonances become increasingly important. Both aspects are highlighted by numerically studying relevant nano-antennas.

  19. A Diagnostic for Electric Field Measurements in the Near/Far-Field Regions of ICRF Antenna

    Science.gov (United States)

    Martin, E. H.; Caughman, J. B. O.; Isler, R. C.

    2015-11-01

    The physics mechanisms of wave heating and current drive processes in the bulk hot plasma are generally well identified. However, details of the wave-plasma interaction with a material surface in the cold plasma edge are still not fully understood. The driver behind this interaction is the time-periodic wave electric field and is referred to as the near/far-field depending on the location with respect to the antenna. Various models have been formulated to capture the near/far-field physics but have not been tested experimentally. Thus, a diagnostic capable of measuring the electric field with temporal and 3D-spatial resolution is critical for confidence in the codes used to design next generation ICRF antennas. This research is focused on the development of a laser based spectroscopic technique, Doppler-free saturation spectroscopy (DFSS), and its implementation to study near/far-field physics. Using DFSS the spectra line profile of various electronic transitions are measured and fit to a quantum mechanical model incorporating both magnetic and dynamic electric field operators. The electric field direction and magnitude are extracted from the fit. The experimental setup and planned experiments will be discussed. Additionally, initial measurements of fitted Hδ spectrum under the influence of known electric and magnetic fields will be presented.

  20. Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Borglin, Johan [Biomedical Photonics Group, Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Department of Physics, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Guldbrand, Stina [Department of Physics, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Evenbratt, Hanne [Pharmaceutical Technology, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Kemigården 4, 412 96 Gothenburg (Sweden); Kirejev, Vladimir; Ericson, Marica B., E-mail: marica.ericson@chem.gu.se [Biomedical Photonics Group, Department of Chemistry and Molecular Biology, University of Gothenburg, Kemivägen 10, 412 96 Gothenburg (Sweden); Grönbeck, Henrik [Department of Applied Physics, Chalmers University of Technology, Kemivägen 9, 412 96 Gothenburg (Sweden)

    2015-12-07

    Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region.

  1. Engineering antenna radiation patterns via quasi-conformal mappings.

    Science.gov (United States)

    García-Meca, Carlos; Martínez, Alejandro; Leonhardt, Ulf

    2011-11-21

    We use a combination of conformal and quasi-conformal mappings to engineer isotropic electromagnetic devices that modify the omnidirectional radiation pattern of a point source. For TE waves, the designed devices are also non-magnetic. The flexibility offered by the proposed method is much higher than that achieved with conformal mappings. As a result, it is shown that complex radiation patterns can be achieved, which can combine high directivity in a desired number of arbitrary directions and isotropic radiation in other specified angular ranges. In addition, this technique enables us to control the power radiated in each direction to a certain extent. The obtained results are valid for any part of the spectrum. The potential of this method is illustrated with some examples. Finally, we study the frequency dependence of the considered devices and propose a practical dielectric implementation.

  2. Capacitively Loaded Loop-Based Antennas with Reconfigurable Radiation Patterns

    Directory of Open Access Journals (Sweden)

    Saber Dakhli

    2015-01-01

    Full Text Available A class of metamaterial-inspired antennas having reconfigurable radiation patterns is proposed. They consist of a driven monopole antenna with one- and two-capacitively loaded loop (CLL, near field resonant parasitic elements. Two configurations are studied by considering the state of these CLL elements as being either open or closed configurations. Simulation results explain the design features and demonstrate that the structure can change its beam direction simply by controlling the switched states. Two prototypes with one- and two-CLL elements were fabricated and tested. The measured impedance mismatch and radiation pattern results are presented and compared to the corresponding simulated values.

  3. Experimental Verification of the Spectral Shift between Near- and Far-Field Peak Intensities of Plasmonic Nanoantennas

    CERN Document Server

    Alonso-Gonzalez, P; Neubrech, F; Huck, Christian; Chen, J; Golmar, F; Casanova, F; Hueso, L E; Pucci, A; Aizpurua, J; Hillenbrand, R

    2013-01-01

    Theory predicts a distinct spectral shift between the near- and far-field optical responses of plasmonic antennas. Here we combine near-field optical microscopy and far-field spectroscopy of individual infrared-resonant nanoantennas to verify experimentally this spectral shift. Numerical calculations corroborate our experimental results. We furthermore discuss the implications of this effect in surface-enhanced infrared spectroscopy (SEIRS).

  4. Ultraslow, slow, or fast spreading ridges: Arm wrestling between mantle convection and far-field tectonics

    Science.gov (United States)

    Husson, Laurent; Yamato, Philippe; Bezos, Antoine

    2016-04-01

    Oceanic spreading rates are highly variable, and these variations are known to correlate to a variety of surface observables, like magmatic production, heat flow or bathymetry. This correlation lead to classify ridges into fast and slow spreading ridges, but also into the more peculiar ultraslow spreading regime. Here we explore the dynamic relationships between spreading ridges, plate tectonics and mantle flow. We first focus on the thermal signature of the mantle, that we infer from the global S-wave seismic tomography model of Debayle and Ricard (2012). We show that the thermal structure of ridges gradually departs from the half-space cooling model for slow, and above all ultraslow spreading ridges. We also infer that the sublithospheric mantle temperature decreases by more than 150 degrees C from fast to ultraslow spreading regimes. Both observations overall indicate that the mantle convection pattern is increasingly chaotic underneath slow and ultraslow spreading ridges. We suggest that this is due to far-field tectonics at the other ends of lithospheric plates: not only it modulates the spreading rates but it also alters the convection regime by obstructing the circulation of plates, which in turn modifies the surface kinematic conditions for the convecting mantle. We test this hypothesis using a thermo-mechanical model that represents a convection cell carrying a continental lithosphere atop. The continent gradually drifts away from the spreading ridge, from which the oceanic lithosphere grows and cools while the continent eventually collides at the opposite side. In turn, this event drastically modifies the upper kinematic condition for the convecting mantle that evolves from a mobile lid regime to an almost stagnant lid regime. Implications on spreading ridges are prominent: heat advection decreases with respect to thermal conduction, which causes the oceanic lithosphere to thicken faster; the oceanic plates get compressed and destabilized by a growing

  5. Controlling activation site density by low-energy far-field stimulation in cardiac tissue

    Science.gov (United States)

    Hörning, Marcel; Takagi, Seiji; Yoshikawa, Kenichi

    2012-06-01

    Tachycardia and fibrillation are potentially fatal arrhythmias associated with the formation of rotating spiral waves in the heart. Presently, the termination of these types of arrhythmia is achieved by use of antitachycardia pacing or cardioversion. However, these techniques have serious drawbacks, in that they either have limited application or produce undesirable side effects. Low-energy far-field stimulation has recently been proposed as a superior therapy. This proposed therapeutic method would exploit the phenomenon in which the application of low-energy far-field shocks induces a large number of activation sites (“virtual electrodes”) in tissue. It has been found that the formation of such sites can lead to the termination of undesired states in the heart and the restoration of normal beating. In this study we investigate a particular aspect of this method. Here we seek to determine how the activation site density depends on the applied electric field through in vitro experiments carried out on neonatal rat cardiac tissue cultures. The results indicate that the activation site density increases exponentially as a function of the intracellular conductivity and the level of cell isotropy. Additionally, we report numerical results obtained from bidomain simulations of the Beeler-Reuter model that are quantitatively consistent with our experimental results. Also, we derive an intuitive analytical framework that describes the activation site density and provides useful information for determining the ratio of longitudinal to transverse conductivity in a cardiac tissue culture. The results obtained here should be useful in the development of an actual therapeutic method based on low-energy far-field pacing. In addition, they provide a deeper understanding of the intrinsic properties of cardiac cells.

  6. Predicting benzene vapor concentrations with a near field/far field model.

    Science.gov (United States)

    Nicas, Mark; Neuhaus, John

    2008-09-01

    Published data on benzene vapor concentrations in work simulation settings were used to examine the predictive ability of a near field/far field vapor dispersion model with an exponentially decreasing vapor emission rate. A given simulation involved two 15-min periods of applying a known volume of benzene-containing liquid to equipment on a worktable in a room with a measured air exchange rate. Replicate personal breathing zone (15-min time-weighted average, TWA) and room area (1-hr TWA) air samples were collected. In our modeling, the benzene vapor concentration in the near field zone (at the worktable) represented the personal breathing zone exposure level, and the benzene vapor concentration in the far field zone represented the room area concentration. Across 10 simulation combinations of two factors (the mass of benzene applied and the room air exchange rate), the mean of the personal breathing zone exposure levels ranged from 0.2 to 9.9 mg m(-3), and the mean of the room area concentrations ranged from 0.05 to 5.05 mg m(-3). Our model provided reasonably accurate estimates of the measured benzene vapor concentrations. Linear regression of the mean measured personal breathing zone exposure versus the predicted near field concentration yielded slope = 0.93 and r(2) = 0.94; the null hypothesis that the true slope equals one was not rejected (p-value = 0.39). Linear regression of the mean measured room area concentration versus the predicted far field concentration yielded slope = 0.90 and r(2) = 0.94; the null hypothesis that the true slope equals one was not rejected (p-value = 0.20). Other statistical tests showed no significant differences between measured and predicted values. In addition, most predicted concentrations fell within an approximate range of one-half to twofold the respective measured concentrations.

  7. A NUMERICAL MODEL OF FAR-FIELD COD CONCENTRATION DISTRIBUTION FOR NATURAL RIVER

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A far-field numerical model is developed to simulate jet pollution into natural rivers. Its character is to compute the velocity and pollution concentration separately. The velocity is computed by SIMPLEC algorithm in boundary-fitted coordinate systems. The pollution concentration distribution is computed by developed QUAL-IIm and QAIIL 2D program. The present model was applied to the Xiantao section of the Hanjiang River a tributary of Yangtze River, and Xiangjiang River. The flow field and COD distribution are in good agreement with field data.

  8. Fourier method for recovering acoustic sources from multi-frequency far-field data

    Science.gov (United States)

    Wang, Xianchao; Guo, Yukun; Zhang, Deyue; Liu, Hongyu

    2017-03-01

    We consider an inverse source problem of determining a source term in the Helmholtz equation from multi-frequency far-field measurements. Based on the Fourier series expansion, we develop a novel non-iterative reconstruction method for solving the problem. A promising feature of this method is that it utilizes the data from only a few observation directions for each frequency. Theoretical uniqueness and stability analysis are provided. Numerical experiments are conducted to illustrate the effectiveness and efficiency of the proposed method in both two and three dimensions.

  9. Far-field head-media optical interaction in heat-assisted magnetic recording

    CERN Document Server

    Yang, Ruoxi; Klemmer, Timothy; Olson, Heidi; Zhang, Deming; Perry, Tyler; Yin, Huaqing; Hipwell, Roger; Thiele, Jan-Ulrich; Tang, Huan; Seigler, Mike

    2015-01-01

    We have used a plane-wave expansion method to theoretically study the far-field head-media optical interaction in HAMR. For the ASTC media stack specifically, we notice the outstanding sensitivity related to interlayer's optical thickness for media reflection and magnetic layer's light absorption. With 10-nm interlayer thickness change, the recording layer absorption can be changed by more than 25%. The 2-D results are found to correlate well with full 3-D model and magnetic recording tests on flyable disc with different interlayer thickness.

  10. Phase measurement and far-field reconstruction on externally coupled laser diode arrays.

    Science.gov (United States)

    Niebuhr, Mario; Heuer, Axel

    2017-06-26

    Passive coherent combination of several discrete low power laser diodes is a promising way to overcome the issue of degrading beam quality when scaling single emitters to > 10 W output power. Such systems would be an efficient alternative to current high power sources, yet they suffer from fatal coherence loss when operated well above threshold. We present a new way to obtain detailed coherence information for laser diode arrays using a spatial light modulator to help identify the underlying decoherence processes. Reconstruction tests of the emitted far-field distribution are conducted to evaluate the performance of our setup.

  11. Characterization of Nonparaxial Truncated Cosine-Gaussian Beams and the Beam Quality in the Far Field

    Institute of Scientific and Technical Information of China (English)

    KANG Xiao-Ping; L(U) Bai-Da

    2006-01-01

    @@ The analytical expression characterizing the propagation of nonparaxial truncated cosine-Gaussian (CoG) beams in free space is derived, and some special cases are discussed. The extended power in the bucket (PIB) is proposed to characterize the beam quality of nonparaxial truncated beams in the far field. It is shown that the extended PIB is applicable to nonparaxial truncated beams, and the PIB of nonparaxial truncated CoG beams depends on the decentred parameter, waist-width-to-wavelength ratio, truncation parameter, and bucket size chosen.

  12. The Optical Chirality Flux as a Useful Far-Field Probe of Chiral Near Fields

    CERN Document Server

    Poulikakos, Lisa V; McPeak, Kevin M; Burger, Sven; Niegemann, Jens; Hafner, Christian; Norris, David J

    2016-01-01

    To optimize the interaction between chiral matter and highly twisted light, quantities that can help characterize chiral electromagnetic fields near nanostructures are needed. Here, by analogy with Poynting's theorem, we formulate the time-averaged conservation law of optical chirality in lossy dispersive media and identify the optical chirality flux as an ideal far-field observable for characterizing chiral optical near fields. Bounded by the conservation law, we show that it provides precise information, unavailable from circular dichroism spectroscopy, on the magnitude and handedness of highly twisted fields near nanostructures.

  13. Tunable far-field acoustic imaging by two-dimensional sonic crystal with concave incident surface

    Science.gov (United States)

    Shen, Feng-Fu; Lu, Dan-Feng; Zhu, Hong-Wei; Ji, Chang-Ying; Shi, Qing-Fan

    2017-01-01

    An additional concave incident surface comprised of two-dimensional (2D) sonic crystals (SCs) is employed to tune the acoustic image in the far-field region. The tunability is realized through changing the curvature of the concave surface. To explain the tuning mechanism, a simple ray-trace analysis is demonstrated based on the wave-beam negative refractive law. Then, a numerical confirmation is carried out. Results show that both the position and the intensity of the image can be tuned by the introduced concave surface.

  14. Tunable acoustic radiation pattern assisted by effective impedance boundary

    Science.gov (United States)

    Qian, Feng; Quan, Li; Wang, Li-Wei; Liu, Xiao-Zhou; Gong, Xiu-Fen

    2016-02-01

    The acoustic wave propagation from a two-dimensional subwavelength slit surrounded by metal plates decorated with Helmholtz resonators (HRs) is investigated both numerically and experimentally in this work. Owing to the presence of HRs, the effective impedance of metal surface boundary can be manipulated. By optimizing the distribution of HRs, the asymmetric effective impedance boundary will be obtained, which contributes to generating tunable acoustic radiation pattern such as directional acoustic beaming. These dipole-like radiation patterns have high radiation efficiency, no fingerprint of sidelobes, and a wide tunable range of the radiation pattern directivity angle which can be steered by the spatial displacements of HRs. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB921504 and 2011CB707902), the National Natural Science Foundation of China (Grant No.11474160), the Fundamental Research Funds for Central Universities, China (Grant No. 020414380001), the State Key Laboratory of Acoustics, Chinese Academy of Sciences (Grant No. SKLOA201401), the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.

  15. Modelling far field pacing for terminating spiral waves pinned to ischaemic heterogeneities in cardiac tissue

    Science.gov (United States)

    Boccia, E.; Luther, S.; Parlitz, U.

    2017-05-01

    In cardiac tissue, electrical spiral waves pinned to a heterogeneity can be unpinned (and eventually terminated) using electric far field pulses and recruiting the heterogeneity as a virtual electrode. While for isotropic media the process of unpinning is much better understood, the case of an anisotropic substrate with different conductivities in different directions still needs intensive investigation. To study the impact of anisotropy on the unpinning process, we present numerical simulations based on the bidomain formulation of the phase I of the Luo and Rudy action potential model modified due to the occurrence of acute myocardial ischaemia. Simulating a rotating spiral wave pinned to an ischaemic heterogeneity, we compare the success of sequences of far field pulses in the isotropic and the anisotropic case for spirals still in transient or in steady rotation states. Our results clearly indicate that the range of pacing parameters resulting in successful termination of pinned spiral waves is larger in anisotropic tissue than in an isotropic medium. This article is part of the themed issue `Mathematical methods in medicine: neuroscience, cardiology and pathology'.

  16. Metal/Polymer Based Stretchable Antenna for Constant Frequency Far-Field Communication in Wearable Electronics

    KAUST Repository

    Hussain, Aftab M.

    2015-10-06

    Body integrated wearable electronics can be used for advanced health monitoring, security, and wellness. Due to the complex, asymmetric surface of human body and atypical motion such as stretching in elbow, finger joints, wrist, knee, ankle, etc. electronics integrated to body need to be physically flexible, conforming, and stretchable. In that context, state-of-the-art electronics are unusable due to their bulky, rigid, and brittle framework. Therefore, it is critical to develop stretchable electronics which can physically stretch to absorb the strain associated with body movements. While research in stretchable electronics has started to gain momentum, a stretchable antenna which can perform far-field communications and can operate at constant frequency, such that physical shape modulation will not compromise its functionality, is yet to be realized. Here, a stretchable antenna is shown, using a low-cost metal (copper) on flexible polymeric platform, which functions at constant frequency of 2.45 GHz, for far-field applications. While mounted on a stretchable fabric worn by a human subject, the fabricated antenna communicated at a distance of 80 m with 1.25 mW transmitted power. This work shows an integration strategy from compact antenna design to its practical experimentation for enhanced data communication capability in future generation wearable electronics.

  17. Far-field nanoscale infrared spectroscopy of vibrational fingerprints of molecules with graphene plasmons

    Science.gov (United States)

    Hu, Hai; Yang, Xiaoxia; Zhai, Feng; Hu, Debo; Liu, Ruina; Liu, Kaihui; Sun, Zhipei; Dai, Qing

    2016-01-01

    Infrared spectroscopy, especially for molecular vibrations in the fingerprint region between 600 and 1,500 cm−1, is a powerful characterization method for bulk materials. However, molecular fingerprinting at the nanoscale level still remains a significant challenge, due to weak light–matter interaction between micron-wavelengthed infrared light and nano-sized molecules. Here we demonstrate molecular fingerprinting at the nanoscale level using our specially designed graphene plasmonic structure on CaF2 nanofilm. This structure not only avoids the plasmon–phonon hybridization, but also provides in situ electrically-tunable graphene plasmon covering the entire molecular fingerprint region, which was previously unattainable. In addition, undisturbed and highly confined graphene plasmon offers simultaneous detection of in-plane and out-of-plane vibrational modes with ultrahigh detection sensitivity down to the sub-monolayer level, significantly pushing the current detection limit of far-field mid-infrared spectroscopies. Our results provide a platform, fulfilling the long-awaited expectation of high sensitivity and selectivity far-field fingerprint detection of nano-scale molecules for numerous applications. PMID:27460765

  18. Far-field nanoscale infrared spectroscopy of vibrational fingerprints of molecules with graphene plasmons

    Science.gov (United States)

    Hu, Hai; Yang, Xiaoxia; Zhai, Feng; Hu, Debo; Liu, Ruina; Liu, Kaihui; Sun, Zhipei; Dai, Qing

    2016-07-01

    Infrared spectroscopy, especially for molecular vibrations in the fingerprint region between 600 and 1,500 cm-1, is a powerful characterization method for bulk materials. However, molecular fingerprinting at the nanoscale level still remains a significant challenge, due to weak light-matter interaction between micron-wavelengthed infrared light and nano-sized molecules. Here we demonstrate molecular fingerprinting at the nanoscale level using our specially designed graphene plasmonic structure on CaF2 nanofilm. This structure not only avoids the plasmon-phonon hybridization, but also provides in situ electrically-tunable graphene plasmon covering the entire molecular fingerprint region, which was previously unattainable. In addition, undisturbed and highly confined graphene plasmon offers simultaneous detection of in-plane and out-of-plane vibrational modes with ultrahigh detection sensitivity down to the sub-monolayer level, significantly pushing the current detection limit of far-field mid-infrared spectroscopies. Our results provide a platform, fulfilling the long-awaited expectation of high sensitivity and selectivity far-field fingerprint detection of nano-scale molecules for numerous applications.

  19. A Broadband UHF Tag Antenna For Near-Field and Far-Field RFID Communications

    Directory of Open Access Journals (Sweden)

    M. Dhaouadi

    2014-12-01

    Full Text Available The paper deals with the design of passive broadband tag antenna for Ultra-High Frequency (UHF band. The antenna is intended for both near and far fields Radio Frequency Identification (RFID applications. The meander dipole tag antenna geometry modification is designed for frequency bandwidth increasing. The measured bandwidth of the proposed broadband Tag antenna is more than 140 MHz (820–960 MHz, which can cover the entire UHF RFID band. A comparison between chip impedance of datasheet and the measured chip impedance has been used in our simulations. The proposed progressive meandered antenna structure, with an overall size of 77 mm × 14 mm × 0.787 mm, produces strong and uniform magnetic field distribution in the near-field zone. The antenna impedance is matched to common UHF chips in market simply by tuning its capacitive and inductive values since a perfect matching is required in the antenna design in order to enhance the near and the far field communications. Measurements confirm that the designed antenna exhibits good performance of Tag identification for both near-field and far-field UHF RFID applications.

  20. Damage Pattern as a Function of Various Types of Radiation

    Directory of Open Access Journals (Sweden)

    R.G. Ahmed

    2006-01-01

    Full Text Available The number of reports on the effects of various types of radiation is gradually increasing because of weakening of the immune system. Radiation can penetrate into living cells and result in the transfer of radiation energy to the biological material. The absorbed energy can increase the reactive oxygen species and break chemical bonds and cause ionization of different biologically essential macromolecules, such as DNA membrane lipids and proteins. Damage to the cellular membrane release the hydrolytic enzymes responsible for various catabolic processes in the tissues and leads to cell death. An understanding of the pattern in critical cellular structures such as DNA is an important prerequisite for a mechanistic assessment of primary radiation injury. The DNA damage induced by radiation such as base alterations, cross linking, strands breaker chromosomal aberration which may in turn lead to mutations. In order to further explore the harmful effects of radiation. I have produced a variety of effects of radiation on the apoptosis and necrosis. Indeed, the present review has shown that the increase in the oxidative stress (increased endogenous production of the free radicals due to radiation may be a reason for such a damage of the cell membrane, and may lead to harming the cellular elements (such as DNA. Here, one can hypothesize that, the cells with increased sensitivity to oxidative stress may be more susceptible to damage by radiation compared to normal cells. The ultimate biological consequences of this effect are subsequently processed by these cells. Much work remains to be done to firmly establish this concept.

  1. Using Radiation Pattern Measurements for Mobile Handset Performance Evaluation

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Pedersen, Gert Frølund

    2005-01-01

    The mean effective gain (MEG) is an attractive performance measure of mobile handsets, since it incorporates both directional and polarization properties of the handset and environment. In this work the MEG is computed from measured spherical radiation patterns of five different mobile handsets......, both in free space and including a human head & shoulder phantom. Different models of the environment allow a comparison of the MEG obtained for realistic models based on measurements with the total radiated power (TRP) and the total isotropic sensitivity (TIS). All the comparisons are based on the MEG...

  2. Mobile Handset Performance Evaluation Using Radiation Pattern Measurements

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Pedersen, Gert Frølund

    2006-01-01

    The mean effective gain is an attractive performance measure of mobile handsets, since it incorporates both directional and polarization properties of the handset and environment. In this work the mean effective gain is computed from measured spherical radiation patterns of five different mobile...... handsets, both in free space and including a human head & shoulder phantom. Different models of the environment allow a comparison of the mean effective gain obtained for realistic models based on measurements with the total radiated power and the total isotropic sensitivity. All the comparisons are based...

  3. Hilbert-Curve Fractal Antenna With Radiation- Pattern Diversity

    Science.gov (United States)

    Nessel, James A.; Miranda, Felix A.; Zaman, Afroz

    2007-01-01

    A printed, folded, Hilbert-curve fractal microwave antenna has been designed and built to offer advantages of compactness and low mass, relative to other antennas designed for the same operating frequencies. The primary feature of the antenna is that it offers the advantage of radiation-pattern diversity without need for electrical or mechanical switching: it can radiate simultaneously in an end-fire pattern at a frequency of 2.3 GHz (which is in the S-band) and in a broadside pattern at a frequency of 16.8 GHz (which is in the Ku-band). This radiation-pattern diversity could be utilized, for example, in applications in which there were requirements for both S-band ground-to-ground communications and Ku-band ground-to-aircraft or ground-to-spacecraft communications. The lack of switching mechanisms or circuitry makes this antenna more reliable, easier, and less expensive to fabricate than it otherwise would be.

  4. Can two partially coherent cosh-Gaussian beams generate far fields with the same spectral degree of coherence?

    Institute of Scientific and Technical Information of China (English)

    Lü Su-Ye; Lü Bai-Da

    2009-01-01

    Taking partially coherent cosh-Gaussian (ChG) beams as an example of more general partially coherent beams,we have studied the spectral degree of coherence of partially coherent ChG beams in the far field. It is shown that,unlike Gaussian Schell-model (GSM) beams,in the strict sense there do not exist two partially coherent ChG beams which can generate far fields with the same spectral degree of coherence. However,under certain conditions it is possible to find two partially coherent ChG beams with the same spectral degree of coherence in the far field.

  5. Far-field Characteristics of Silver Nanodisk Optical Antenna%银纳米圆盘光天线的远场方向性研究

    Institute of Scientific and Technical Information of China (English)

    李宏光

    2012-01-01

    The near-field distribution of silver nanodisk optical antenna was calculated with Finite-Difference Time-Domain method. The influence to the far-field characteristics by different parameters such as the distance between nanodisk and dipole, thickness and radius of nanodisk, was discussed. The research demonstrated that when the dipole was placed vertically beneath the nanodisk, the variation of thickness or radius could lead to new radiation mode in the far-field pattern and give rise to the enhancement of directivity gain. Through the observation and analysis to near-field, it could be obtained that the new radiation mode was caused by the high order localized surface plasmon(LSP) mode. The optimization results pointed out that as the background material was set as GaN, for the sake of producing high order LSP mode, the suitable distance between nanodisk and dipole was 40 nm. Furthermore, in order to effectively support the high order LSP mode, the thickness and radius of nanodisk were at least 30 nm and 100 nm respectively. These results provided a theoretical reference to master the characteristics of nanodisk optical antenna as well as the practical application in optical devices.%采用时域有限差分方法计算了银纳米圆盘光天线模型的场分布,研究了光偶极天线的远场辐射特性随距离和厚度、半径变化的规律以及影响其远场方向性的因素.研究发现,偶极子垂直放置在银纳米圆盘下方一定距离时,银盘厚度和半径的改变均可使方向性图中出现新的辐射模式,同时方向性增益得到增强.通过对其近场的观察和分析可以得知,新的辐射模式的产生来源于高阶模式的局域表面等离激元.结果表明,背景材料为GaN时,产生高阶模式局域表面等离激元的合适条件为电偶极子距银盘底部40 nm.另外,为了有效地支持高阶模式局域表面等离激元的形成,银盘厚度与半径最小分别为30 nm和100 nm.本文的研究对

  6. Fano resonances in antennas: General control over radiation patterns

    CERN Document Server

    Rybin, Mikhail V; Filonov, Dmitry S; Slobozhanyuk, Alexey P; Belov, Pavel A; Kivshar, Yuri S; Limonov, Mikhail F

    2013-01-01

    The concepts of many optical devices are based on the fundamental physical phenomena such as resonances. One of the commonly used devices is an electromagnetic antenna that converts localized energy into freely propagating radiation and vise versa, offering unique capabilities for controlling electromagnetic radiation. Here we propose a concept for controlling the intensity and directionality of electromagnetic wave scattering in radio-frequency and optical antennas based on the physics of Fano resonances. We develop an analytical theory of spatial Fano resonances in antennas that describes switching of the radiation pattern between the forward and backward directions, and confirm our theory with both numerical calculations and microwave experiments. Our approach bridges the concepts of conventional radio antennas and photonic nanoantennas, and it provides a paradigm for the design of wireless optical devices with various functionalities and architectures.

  7. Automated platform for determination of LEDs spatial radiation pattern

    Science.gov (United States)

    Vladescu, Marian; Vuza, Dan Tudor

    2015-02-01

    Nowadays technologies lead to remarkable properties of the light-emitting diodes (LEDs), making them attractive for more and more applications, such as: interior and exterior lighting, outdoor LED panels, traffic signals, automotive (tail and brake lights, backlighting in dashboard and switches), backlighting of display panels, LCD displays, symbols on switches, keyboards, graphic boards and measuring scales. Usually, LEDs are small light sources consisting of a chip placed into a package, which may bring additional optics to this encapsulated ensemble, resulting in a less or more complex spatial distribution of the light intensity, with particular radiation patterns. This paper presents an automated platform designed to allow a quick and accurate determination of the spatial radiation patterns of LEDs encapsulated in various packages. Keywords: LED, luminous

  8. Computation of unsteady transonic flows through rotating and stationary cascades. 3: Acoustic far-field analysis

    Science.gov (United States)

    Slutsky, S.; Fischer, D.; Erdos, J. I.

    1977-01-01

    A small perturbation type analysis has been developed for the acoustic far field in an infinite duct extending upstream and downstream of an axial turbomachinery stage. The analysis is designed to interface with a numerical solution of the near field of the blade rows and, thereby, to provide the necessary closure condition to complete the statement of infinite duct boundary conditions for the subject problem. The present analysis differs from conventional inlet duct analyses in that a simple harmonic time dependence was not assumed, since a transient signal is generated by the numerical near-field solution and periodicity is attained only asymptotically. A description of the computer code developed to carry out the necessary convolutions numerically is included, as well as the results of a sample application using an impulsively initiated harmonic signal.

  9. Terminating Ventricular Fibrillation Using Pulsed Far-Field Stimulation in Whole Rabbit Hearts

    Science.gov (United States)

    Squires, Amgad; Hornung, Daniel; Bittihn, Philip; Xia Wu, Dong; Krinsky, Valentin; Zabel, Markus; Bodenschatz, Eberhard; Luther, Stefan

    2010-03-01

    During life-threatening cardiac fibrillation, chaotic spatio-temporal dynamics is mediated by vortex-like rotating waves. Current defibrillation strategies rely on global control through high-energy shocks, which may have severe side-effects including traumatic pain and tissue damage. Far-field antifibrillation pacing terminates fibrillation using a train of low-energy electric pulses [1,2]. Using optical mapping in isolated rabbit heart preparations, we evaluate the efficiency and robustness of this approach. We found that a series of pulses at low energies (ventricular fibrillation with a success rate of 95%. We will discuss the physical mechanisms involved.[4pt] [1] F.H. Fenton et al, Circulation 120 467-476 (2009).[0pt] [2] A. Pumir et al., Phys. Rev. Lett. 99, 208101 (2007).

  10. Far-Field Plasmonic Resonance Enhanced Nano-Particle Image Velocimetry within a Micro Channel

    CERN Document Server

    Zhang, Zhili; Haque, Sara S; Zhang, Mingjun

    2010-01-01

    In this paper, a novel far-field plasmonic resonance enhanced nanoparticle-seeded Particle Image Velocimetry (nPIV) has been demonstrated to measure the velocity profile in a micro channel. Chemically synthesized silver nanoparticles have been used to seed the flow in the micro channel. By using Discrete Dipole Approximation (DDA), plasmonic resonance enhanced light scattering has been calculated for spherical silver nanoparticles with diameters ranging from 15nm to 200nm. Optimum scattering wavelength is specified for the nanoparticles in two media: water and air. The diffraction-limited plasmonic resonance enhanced images of silver nanoparticles at different diameters have been recorded and analyzed. By using standard PIV techniques, the velocity profile within the micro channel has been determined from the images.

  11. Exploiting spatiotemporal degrees of freedom for far field subwavelength focusing using time reversal in fractals

    CERN Document Server

    Dupré, Matthieu; Fink, Mathias; Lerosey, Geoffroy

    2016-01-01

    Materials which possess a high local density of states varying at a subwavelength scale theoretically permit to focus waves onto focal spots much smaller than the free space wavelength. To do so metamaterials -manmade composite media exhibiting properties not available in nature- are usually considered. However this approach is limited to narrow bandwidths due to their resonant nature. Here, we prove that it is possible to use a fractal resonator alongside time reversal to focus microwaves onto $\\lambda/15$ subwavelength focal spots from the far field, on extremely wide bandwidths. We first numerically prove that this approach can be realized using a multiple channel time reversal mirror, that utilizes all the degrees of freedom offered by the fractal resonator. Then we experimentally demonstrate that this approach can be drastically simplified by coupling the fractal resonator to a complex medium, here a cavity, that efficiently converts its spatial degrees of freedom into temporal ones. This allows to achie...

  12. Far-field nanoscale infrared spectroscopy of vibrational fingerprints of molecules with graphene plasmons

    CERN Document Server

    Hu, Hai; Zhai, Feng; Hu, Debo; Liu, Ruina; Liu, Kaihui; Sun, Zhipei; Dai, Qing

    2016-01-01

    Infrared spectroscopy, especially for molecular vibrations in the fingerprint region between 600 and 1500 cm-1, is a powerful characterization method for bulk materials. However, molecular fingerprinting at the nanoscale level still remains a significant challenge, due to weak light-matter interaction between micron-wavelengthed infrared light and nano-sized molecules. Here, we demonstrate molecular fingerprinting at the nanoscale level using our specially designed graphene plasmonic structure on CaF2 nanofilm. This structure not only avoids the plasmon-phonon hybridization, but also provides in situ electrically-tunable graphene plasmon covering the entire infrared fingerprint region, which was previously unattainable. In addition, undisturbed and highly-confined graphene plasmon offers simultaneous detection of in-plane and out-of-plane vibrational modes with ultrahigh detection sensitivity down to the sub-monolayer level, significantly pushing the current detection limit of far-field mid-infrared spectrosc...

  13. Multifunctional microscope for far-field and tip-enhanced Raman spectroscopy

    Science.gov (United States)

    Vannier, Christophe; Yeo, Boon-Siang; Melanson, Jeremy; Zenobi, Renato

    2006-02-01

    The development of a versatile and easy-to-use instrument designed for Raman micro- and nanospectroscopy in the visible range is described in this work. An atomic force microscope, an inverted confocal microscope, and a piezostage are combined to perform an accurate and fast tip-laser alignment and to characterize large areas under the same conditions of illumination across the surface. In addition, a metallized tip is used to locally enhance the electromagnetic field and to probe the sample surface leading to in situ chemical analysis at the nanoscale. Both far-field and tip-enhanced Raman spectroscopies (TERS) have been carried out on dye molecules and on nano-objects with short exposure times. The TERS observation of tip-induced sample deformation on single-walled carbon nanotubes is also presented.

  14. Optical far-field super-resolution microscopy using nitrogen vacancy center ensemble in bulk diamond

    Science.gov (United States)

    Li, Shen; Chen, Xiang-dong; Zhao, Bo-Wen; Dong, Yang; Zou, Chong-Wen; Guo, Guang-Can; Sun, Fang-Wen

    2016-09-01

    We demonstrate optical far-field super-resolution microscopy using an array of nitrogen vacancy centers in bulk diamond as near-field optical probes. The local optical field, which transmits through the nanostructures on the diamond surface, is measured by detecting the charge state conversion of the nitrogen vacancy center. Locating the nitrogen vacancy center with a spatial resolution of 6.1 nm is realized with charge state depletion nanoscopy. The nanostructures on the surface of a diamond are then imaged with a resolution below the optical diffraction limit. The results offer an approach to build a general-purpose optical super-resolution microscopy technique and a convenient platform for high spatial resolution quantum sensing with nitrogen vacancy centers.

  15. Spatial frequency characterisation of a far-field superlens to facilitate general purpose imaging

    Science.gov (United States)

    Fadakar Masouleh, Farzaneh; Teal, Paul; Moore, Ciaran

    2016-04-01

    Based on sub-wavelength energy concentration and enhancement of evanescent fields, far-field super-lenses (FSLs) were proposed recently as a means to achieve super-resolution imaging and thus improve the accuracy and resolution of optical microscopy. Comprised of a thin-film plasmonic enhancement layer and a diffraction grating, the performance of FSLs depends greatly on the geometry and size of its constituent parts. In this paper, we aim to characterize the resolution capabilities of FSLs in a novel and meaningful way, while also exploring the effects of non-ideal grating geometries due to fabrication limitations on imaging performance. We use finite element modelling to explore trapezoidal, inverse-trapezoidal, circular, rounded rectangular, and rectangular grating profiles and present a transfer function that quantifies the performance of these grating profiles in terms of their transmission at different wavenumbers.

  16. Far field pacing supersedes anti-tachycardia pacing in a generic model of excitable media

    Energy Technology Data Exchange (ETDEWEB)

    Bittihn, Philip; Parlitz, Ulrich [Drittes Physikalisches Institut, Goettingen University, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Luther, Gisela; Bodenschatz, Eberhard; Krinsky, Valentin; Luther, Stefan [Max Planck Institute for Dynamics and Self-Organization, Bunsenstrasse 10, 37073 Goettingen (Germany)], E-mail: bittihn@physik3.gwdg.de

    2008-10-15

    Removing anchored spirals from obstacles is an important step in terminating cardiac arrhythmia. Conventional anti-tachycardia pacing (ATP) has this ability, but only under very restrictive conditions. In a generic model of excitable media, we demonstrate that for unpinning spiral waves from obstacles this profound limitation of ATP can be overcome by far field pacing (FFP). More specifically, an argument is presented for why FFP includes and thus can only extend the capabilities of ATP in the configurations considered. By numerical simulations, we show that in the model there exists a parameter region in which unpinning is possible by FFP but not by ATP. The relevance of this result regarding clinical applications is discussed.

  17. Far-field and near-field investigation of plasmonic-photonic hybrid laser mode

    CERN Document Server

    Zhang, Taiping; Callard, Ségolène; jamois, Cecile; Letartre, Xavier; Chevalier, Celine; Rojo-Romeo, Pedro; Devif, Brice; Viktorovitch, Pierre

    2014-01-01

    We report an approach to achieve this goal via build a plasmonic-dielectric photonic hybrid system. We induce a defect mode based photonic crystal (PC) cavity to work as a intermedium storage as well as a near-field light source to excite a plasmonic nanoantenna (NA). In this way, a plasmonic-photonic nano-laser source is created in present experiment. The coupling condition between the two elements is investigated in far-field and near-field level. We found that the NA reduces the Q-factor of the PC-cavity. Meanwhile, the NA concentrates and enhances the laser emission of the PC-cavity. This novel hybrid dielectric-plasmonic structure may open a new avenue in the generation of nano-light sources, which can be applied in areas such as optical information storage, non-linear optics, optical trapping and detection, integrated optics, etc.

  18. Image restoration for indirectly far-field image using microlenses array integrated with LCD

    Science.gov (United States)

    Yang, Fugui; Wang, Anting; Lei, Dong; Zhe, Cui; Ming, Hai

    2010-10-01

    Image restoration for constructing high-spatial-resolution images in an imaging system which realizes indirectly far-filed imaging by integrating the microlenses array with LCD is reported. We have investigated the indirectly far-field imaging condition where adjacent sampling points contribute the detected signal. Experimental setup with microlens of 500 μm diameter and 8 mm focal length is built to prove this condition by studying performance of image restoration using modified point spread function (PSF). Since any one iterative method is not optimal for all image deblurring problems, some deblurring algorithms including direct deconvolution and iterative deconvolution are applied to our imaging system and we compared the effectiveness of these iterative procedures to choose right one for our use.

  19. Near- and far-field properties of plasmonic oligomers under radially and azimuthally polarized light excitation.

    Science.gov (United States)

    Yanai, Avner; Grajower, Meir; Lerman, Gilad M; Hentschel, Mario; Giessen, Harald; Levy, Uriel

    2014-05-27

    We present a comprehensive experimental and theoretical study on the near- and far-field properties of plasmonic oligomers using radially and azimuthally polarized excitation. These unconventional polarization states are perfectly matched to the high spatial symmetry of the oligomers and thus allow for the excitation of some of the highly symmetric eigenmodes of the structures, which cannot be excited by linearly polarized light. In particular, we study hexamer and heptamer structures and strikingly find very similar optical responses, as well as the absence of a Fano resonance. Furthermore, we investigate the near-field distributions of the oligomers using near-field scanning optical microscopy (NSOM). We observe significantly enhanced near-fields, which arise from efficient excitation of the highly symmetric eigenmodes by the radially and azimuthally polarized light fields. Our study opens up possibilities for tailored light-matter interaction, combining the design freedom of complex plasmonic structures with the remarkable properties of radially and azimuthally polarized light fields.

  20. Optical far-field super-resolution microscopy using nitrogen vacancy center ensemble in bulk diamond

    CERN Document Server

    Li, Shen; Zhao, Bo-Wen; Dong, Yang; Zou, Chong-Wen; Guo, Guang-Can; Sun, Fang-Wen

    2016-01-01

    We demonstrate an optical far-field super-resolution microscopy using array of nitrogen vacancy centers in bulk diamond as near-field optical probes. The local optical field, which transmits through the nanostructures on the diamond surface, is measured by detecting the charge state conversion of nitrogen vacancy center. And the locating of nitrogen vacancy center with spatial resolution of 6.1 nm is realized with the charge state depletion nanoscopy. The nanostructures on the surface of diamond are then imaged with resolution below optical diffraction limit. The results offer an approach to built a general-purpose optical super-resolution microscopy and a convenient platform for high spatial resolution quantum sensing with nitrogen vacancy center.

  1. Planar Near-Field Phase Retrieval Using GPUs for Accurate THz Far-Field Prediction

    Science.gov (United States)

    Junkin, Gary

    2013-04-01

    With a view to using Phase Retrieval to accurately predict Terahertz antenna far-field from near-field intensity measurements, this paper reports on three fundamental advances that achieve very low algorithmic error penalties. The first is a new Gaussian beam analysis that provides accurate initial complex aperture estimates including defocus and astigmatic phase errors, based only on first and second moment calculations. The second is a powerful noise tolerant near-field Phase Retrieval algorithm that combines Anderson's Plane-to-Plane (PTP) with Fienup's Hybrid-Input-Output (HIO) and Successive Over-Relaxation (SOR) to achieve increased accuracy at reduced scan separations. The third advance employs teraflop Graphical Processing Units (GPUs) to achieve practically real time near-field phase retrieval and to obtain the optimum aperture constraint without any a priori information.

  2. An atmospheric backscatter model on wind measurements using far-field approximation method

    Institute of Scientific and Technical Information of China (English)

    SHU Weiping; ZHAO Zhengyu

    2007-01-01

    A backscatter model was developed for measuring wind field with the far-field approximation method.The theoretical computation and computer simulations with one spatial dimension show that this model can realistically describe the physical meaning and process of the three methods in wind measurements including the spaced antenna (SA) method,Doppler beam swing (DBS) method,and spaced interferometry (SI).The computational difficulties of the traditional theoretical model cannot only be smoothed away,but common characteristics and differences of the three methods can be compared deeply.The comparison of the numerical results between the Wuhan medium frequency (MF) radar (30° N,114° E) observation and the computer simulation of the full correlation analysis (FCA) of the SA method indicates that the two results agree very well and this model has practical application.

  3. Far field emission profile of pure wurtzite InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Bulgarini, Gabriele, E-mail: g.bulgarini@tudelft.nl; Reimer, Michael E.; Zwiller, Val [Kavli Institute of Nanoscience, Delft University of Technology, Delft (Netherlands); Dalacu, Dan; Poole, Philip J.; Lapointe, Jean [National Research Council, Ottawa, Ontario, K1A 0R6 (Canada)

    2014-11-10

    We report on the far field emission profile of pure wurtzite InP nanowires in comparison to InP nanowires with predominantly zincblende crystal structure. The emission profile is measured on individual nanowires using Fourier microscopy. The most intense photoluminescence of wurtzite nanowires is collected at small angles with respect to the nanowire growth axis. In contrast, zincblende nanowires present a minimum of the collected light intensity in the direction of the nanowire growth. Results are explained by the orientation of electric dipoles responsible for the photoluminescence, which is different from wurtzite to zincblende. Wurtzite nanowires have dipoles oriented perpendicular to the nanowire growth direction, whereas zincblende nanowires have dipoles oriented along the nanowire axis. This interpretation is confirmed by both numerical simulations and polarization dependent photoluminescence spectroscopy. Knowledge of the dipole orientation in nanostructures is crucial for developing a wide range of photonic devices such as light-emitting diodes, photodetectors, and solar cells.

  4. Far-Field Distributions of Double-Heterostructure Diode Lasers: an Improved Non-Equiphase Model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhi-Guo; DUAN Kai-Liang; LU Bai-Da

    2007-01-01

    A non-equiphase Gaussian model is proposed to simulate the far-field distributions ofdouble-heterostructure diode lasers, which is physically reasonable because the phase along the junction of diode lasers could not be equal. A comparison of the numerically calculated intensity profiles in using the equal phase and non-equiphase models with the experimentally measured intensity profiles given by Nemoto shows that in the x direction perpendicular to the junction plane, the non-equiphase Gaussian model is as good as the equal phase Gaussian model. Specifically,in the y direction parallel to the junction plane and the 45° direction with respect to the x axis in the xoy plane,the numerical results by using the non-equiphase model are in good agreement with the experimental data, as the propagation distance is larger than a certain value.

  5. Femtosecond refractive-index tailoring of an optical fiber and phase retrieval from far-field measurements

    DEFF Research Database (Denmark)

    Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul

    2013-01-01

    A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation.......A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation....

  6. Realization of periodic and quasiperiodic microstructures with sub-diffraction-limit feature sizes by far-field holographic lithography

    Science.gov (United States)

    Yang, Yi; Wang, Guo Ping

    2006-09-01

    The authors experimentally demonstrate a far-field holography for the realization of Ag nanoparticles-embedded periodic and quasiperiodic microstructures with feature sizes beyond the diffraction limit. Periodic cylindrical nanoshell arrays with about 240nm hole diameter and 12-fold symmetry quasiperiodic structures with 220nm feature sizes are achieved, respectively, by using a 632.8nm laser beam. Our results imply that conventional far-field optical technology is capable of fabricating nanostructures in modern micromanufacture.

  7. Femtosecond refractive-index tailoring of an optical fiber and phase retrieval from far-field measurements

    DEFF Research Database (Denmark)

    Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul;

    2013-01-01

    A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation.......A refractive-index change is written inside an optical fiber close to the end face by femtosecond laser light. The induced phase change is measured by analyzing the far-field intensity profiles before and after the irradiation....

  8. Phase-Based Adaptive Estimation of Magnitude-Squared Coherence Between Turbofan Internal Sensors and Far-Field Microphone Signals

    Science.gov (United States)

    Miles, Jeffrey Hilton

    2015-01-01

    A cross-power spectrum phase based adaptive technique is discussed which iteratively determines the time delay between two digitized signals that are coherent. The adaptive delay algorithm belongs to a class of algorithms that identifies a minimum of a pattern matching function. The algorithm uses a gradient technique to find the value of the adaptive delay that minimizes a cost function based in part on the slope of a linear function that fits the measured cross power spectrum phase and in part on the standard error of the curve fit. This procedure is applied to data from a Honeywell TECH977 static-engine test. Data was obtained using a combustor probe, two turbine exit probes, and far-field microphones. Signals from this instrumentation are used estimate the post-combustion residence time in the combustor. Comparison with previous studies of the post-combustion residence time validates this approach. In addition, the procedure removes the bias due to misalignment of signals in the calculation of coherence which is a first step in applying array processing methods to the magnitude squared coherence data. The procedure also provides an estimate of the cross-spectrum phase-offset.

  9. The pathology of ionizing radiation as defined by morphologic patterns

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Luis Felipe [Stanford Univ. School of Medicine and Veterans Affairs Health Care System, Palo Alto, CA (United States)

    2005-02-01

    This article presents a brief description of the effects of ionizing radiation in human tissues, as seen by the Pathologist. The lesions that occur in multiple organ/tissues will be discussed, dividing them into those that affect (a) the parenchyma or epithelia, (b) the stromal elements, and (c) the blood vessels. Since not all lesions fit into these patterns, the exceptions will be described as characteristic organ lesions. Unless specified otherwise the alterations presented are those that result from electromagnetic radiation (x-rays and gamma rays) as used for clinical radiation therapy. Most of the material presented will be delayed injury (i.e. months-to-years after exposure). The epithelial/parenchymal lesions include atrophy, necrosis, metaplasia, cellular atypia, dysplasia, and neoplasia. The common stromal lesions--the best recognized by pathologists--include fibrosis, fibrinous exudates, necrosis (with a paucity of cellular inflammatory exudates), and atypical fibroblasts. The vascular lesions are quite consistent: most often they affect the microvessels (capillaries, sinusoids) producing lethal and sublethal damage to the endothelial cells, with capillary rupture or thrombosis. Medium-size vessels show neointimal proliferation, fibrinoid necrosis, thrombosis, or acute arteritis. Damage in large vessels is less common; it occurs more in arteries than in veins and includes neointimal proliferation, atheromatosis, thrombosis and rupture (a dramatic complication). Some of the characteristic organ lesions are veno-occlusive liver disease, acute radiation pneumonitis, permanent bone marrow hypoplasia or aplasia, and colitis cystica profunda. Neoplasms are a well-recognized delayed complication of radiation and will not be described in detail. It is important to remember that there are no pathognomonic features of injuries produced by ionizing radiation. Nonetheless, although not specific individually, the combined features are characteristic enough to be

  10. Far-Field to Near-Field Coupling for Enhancing Light-Matter Interaction

    Science.gov (United States)

    Bonakdar, Alireza

    This thesis reports on theoretical, modeling, and experimental research within the framework of a key scientific question, which is enhancing the coupling between diffraction-limited far-field and sub-wavelength quantum emitter/absorber. A typical optoelectronic device delivers an optical process such as light detection (e.g. photodetector) or light intensity modulation (e.g. electro-absorptive modulator). In conventional devices, optical process is in the form of far-field or guided wave modes. The main aim of this thesis is to show that converting these modes into near-field domain can enhance the performance of the optoelectronic device. Light in the form of far-field can be converted into near-field domain by the optical antenna. Among different optoelectronic devices, this thesis focuses mainly on integrating the optical antenna with infrared photodetectors. The available semiconductors have weak infrared absorption that reduces light detection efficiency. Integration of the optical antenna with infrared absorber (such as quantum wells in quantum well infrared photodetector (QWIP)) increases the infrared absorption. Particularly this integration is favorable as the optical antenna has low metallic loss in infrared region. The author of this thesis believes that optical antenna has unique properties in confining light on the scale of deep sub-wavelength, enhancing electric field intensity and delivering optical energy to semiconductor absorbers. These properties are reaching into practical applications only if overall optical performance is low loss, parameter free (independent of optical parameters such a polarization and angle of incident) and broadband. In this thesis, the integration of optical antenna with infrared photodetectors and thermophotovoltaic are researched and developed which satisfy the aforementioned criteria. In addition, several different optical antennas have been designed, fabricated and characterized in order to analyze and demonstrate

  11. Terahertz plasmonic laser radiating in an ultra-narrow beam

    CERN Document Server

    Wu, Chongzhao; Reno, John L; Kumar, Sushil

    2016-01-01

    Plasmonic lasers (spasers) generate coherent surface-plasmon-polaritons (SPPs) and could be realized at subwavelength dimensions in metallic cavities for applications in nanoscale optics. Plasmonic cavities are also utilized for terahertz quantum-cascade lasers (QCLs), which are the brightest available solid-state sources of terahertz radiation. A long standing challenge for spasers is their poor coupling to the far-field radiation. Unlike conventional lasers that could produce directional beams, spasers have highly divergent radiation patterns due to their subwavelength apertures. Here, we theoretically and experimentally demonstrate a new technique for implementing distributed-feedback (DFB) that is distinct from any other previously utilized DFB schemes for semiconductor lasers. The so-termed antenna-feedback scheme leads to single-mode operation in plasmonic lasers, couples the resonant SPP mode to a highly directional far-field radiation pattern, and integrates hybrid SPPs in surrounding medium into the ...

  12. 光偶极天线的远场方向性研究%Study of far-field directivity of optical dipole antenna

    Institute of Scientific and Technical Information of China (English)

    蒋双凤; 孔凡敏; 李康; 高晖

    2011-01-01

    By simulating the field distributions of two optical dipole antenna models with the finite-difference time-domain (FDTD) method, the variation regularity of their far-field radiation with their length increasing and the factors which can influence their far-field directivity are studied. The results show that the variation regularity of optical dipole antenna is analogous to that of classic symmetrical dipole antenna. But in the far-field directivity plot of optical dipole antenna, sidelobes occur much more quickly, owing to the existence of high-order localized surface plasmon modes. These results hold a significant promise of improving the performance of optical antennas.%用时域有限差分方法模拟了两种光偶极天线模型的场分布,研究了光偶极天线的远场辐射特性随其长度增加而变化的规律以及影响其远场方向性的因素,发现光偶极天线的远场方向性随其长度增加而变化的规律类似于经典对称振子天线的相应规律.但高阶局域表面等离激元模式的存在使得光偶极天线的远场辐射图更快地出现了旁瓣.这些发现对于提高光天线的性能具有重要意义.

  13. Tsunami Size Distributions at Far-Field Locations from Aggregated Earthquake Sources

    Science.gov (United States)

    Geist, E. L.; Parsons, T.

    2015-12-01

    The distribution of tsunami amplitudes at far-field tide gauge stations is explained by aggregating the probability of tsunamis derived from individual subduction zones and scaled by their seismic moment. The observed tsunami amplitude distributions of both continental (e.g., San Francisco) and island (e.g., Hilo) stations distant from subduction zones are examined. Although the observed probability distributions nominally follow a Pareto (power-law) distribution, there are significant deviations. Some stations exhibit varying degrees of tapering of the distribution at high amplitudes and, in the case of the Hilo station, there is a prominent break in slope on log-log probability plots. There are also differences in the slopes of the observed distributions among stations that can be significant. To explain these differences we first estimate seismic moment distributions of observed earthquakes for major subduction zones. Second, regression models are developed that relate the tsunami amplitude at a station to seismic moment at a subduction zone, correcting for epicentral distance. The seismic moment distribution is then transformed to a site-specific tsunami amplitude distribution using the regression model. Finally, a mixture distribution is developed, aggregating the transformed tsunami distributions from all relevant subduction zones. This mixture distribution is compared to the observed distribution to assess the performance of the method described above. This method allows us to estimate the largest tsunami that can be expected in a given time period at a station.

  14. Probabilistic tsunami hazard assessment at Seaside, Oregon, for near- and far-field seismic sources

    Science.gov (United States)

    GonzáLez, F. I.; Geist, E. L.; Jaffe, B.; KâNoǧLu, U.; Mofjeld, H.; Synolakis, C. E.; Titov, V. V.; Arcas, D.; Bellomo, D.; Carlton, D.; Horning, T.; Johnson, J.; Newman, J.; Parsons, T.; Peters, R.; Peterson, C.; Priest, G.; Venturato, A.; Weber, J.; Wong, F.; Yalciner, A.

    2009-11-01

    The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment (PSHA). Application of the methodology to Seaside, Oregon, has yielded estimates of the spatial distribution of 100- and 500-year maximum tsunami amplitudes, i.e., amplitudes with 1% and 0.2% annual probability of exceedance. The 100-year tsunami is generated most frequently by far-field sources in the Alaska-Aleutian Subduction Zone and is characterized by maximum amplitudes that do not exceed 4 m, with an inland extent of less than 500 m. In contrast, the 500-year tsunami is dominated by local sources in the Cascadia Subduction Zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km. The primary sources of uncertainty in these results include those associated with interevent time estimates, modeling of background sea level, and accounting for temporal changes in bathymetry and topography. Nonetheless, PTHA represents an important contribution to tsunami hazard assessment techniques; viewed in the broader context of risk analysis, PTHA provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard, which can then be combined with vulnerability and exposure to yield estimates of tsunami risk.

  15. Characterization of far-field jet flows from complex nozzles via Particle Tracking Velocimetry

    Science.gov (United States)

    Kim, Jin-Tae; Liberzon, Alex; Zuniga Zamalloa, Carlo; Chamorro, Leonardo P.

    2014-11-01

    Understanding the advection, diffusion and mixing of turbulence and scalars of jet flows under various geometric configurations and Reynolds numbers is of high relevance in environmental and engineering applications. In this experimental study, we characterize the far-field turbulence of jet flows in the proximity of twelve rotor diameters downstream of a series of complex nozzle geometries. The jet flows are released into a still body of water from a series of nozzles of different cross sections but with common hydraulic diameter dh = 0.01 m at a Reynolds number Re = U0*dh/ ν approx. 7000, where U0 is the flow velocity at the outlet of the jet and ν is the kinematic viscosity of the flow. The system is closed-loop and seeded with particles of 100 μm diameter. Results are analyzed from Lagrangian and Eulerian frames of references via 3D particle tracking velocimetry (OpenPTV, www.openptv.net). Lagrangian features of the particles are characterized in terms of the nozzle geometries and high-order turbulence statistics are obtained at various planes within the interrogation volume, which mimics 3D PIV.

  16. Far-Field Voice Activity Detection and Its Applications in Adverse Acoustic Environments

    DEFF Research Database (Denmark)

    Petsatodis, Theodoros

    2012-01-01

    Voice Activity Detection (VAD), being in the focus of speech processing research for many years, is nowadays a mature technology with application in several sectors. Embedded VAD components in telecommunications systems (like in cellular telephony) attempt to reduce power consumption of transmitt......Voice Activity Detection (VAD), being in the focus of speech processing research for many years, is nowadays a mature technology with application in several sectors. Embedded VAD components in telecommunications systems (like in cellular telephony) attempt to reduce power consumption...... of transmitters and bandwidth utilization. VAD technology is also integrated in speech-processing systems, such as Speaker Identification, Automatic Event Detection, and Automatic Speech Recognition, to prevent their operation in the absence of speech, and thus reduce the error rates of each of these systems....... The performance of VAD systems depends strongly on various factors, including the discriminative ability of the classification criterion employed, the dynamics of the additive noise and the signal to noise ratio. Speech signals transmitted within reverberant enclosures and captured using far-field microphones...

  17. Reconstruction of far-field tsunami amplitude distributions from earthquake sources

    Science.gov (United States)

    Geist, Eric L.; Parsons, Thomas E.

    2016-01-01

    The probability distribution of far-field tsunami amplitudes is explained in relation to the distribution of seismic moment at subduction zones. Tsunami amplitude distributions at tide gauge stations follow a similar functional form, well described by a tapered Pareto distribution that is parameterized by a power-law exponent and a corner amplitude. Distribution parameters are first established for eight tide gauge stations in the Pacific, using maximum likelihood estimation. A procedure is then developed to reconstruct the tsunami amplitude distribution that consists of four steps: (1) define the distribution of seismic moment at subduction zones; (2) establish a source-station scaling relation from regression analysis; (3) transform the seismic moment distribution to a tsunami amplitude distribution for each subduction zone; and (4) mix the transformed distribution for all subduction zones to an aggregate tsunami amplitude distribution specific to the tide gauge station. The tsunami amplitude distribution is adequately reconstructed for four tide gauge stations using globally constant seismic moment distribution parameters established in previous studies. In comparisons to empirical tsunami amplitude distributions from maximum likelihood estimation, the reconstructed distributions consistently exhibit higher corner amplitude values, implying that in most cases, the empirical catalogs are too short to include the largest amplitudes. Because the reconstructed distribution is based on a catalog of earthquakes that is much larger than the tsunami catalog, it is less susceptible to the effects of record-breaking events and more indicative of the actual distribution of tsunami amplitudes.

  18. Far-field method for the characterisation of three-dimensional fields: vectorial polarimetry

    Directory of Open Access Journals (Sweden)

    Dainty C.

    2010-06-01

    Full Text Available The first attempt to completely characterise a three-dimensional field was done by Ellis and Dogariu with excellent results reported [1] . However, their method is based on near-field techniques, which limits its range of applications. In this work, we present an alternative far-field method for the characterisation of the three-dimensional field that results from the interaction of a tightly focused three-dimensional field [2] with a sub-resolution specimen. Our method is based on the analysis of the scattering-angle-resolved polarisation state distribution across the exit pupil of a high numerical aperture (NA collector lens using standard polarimetry techniques. Details of the method, the experimental setup built to verify its capabilities, and numerical and first experimental evidence demonstrating that the method allows for high sensitivit y on sub-resolution displacements of a sub-resolution specimen shall be presented [3]. This work is funded by Science Foundation Ireland grant No. 07/IN.1/I906 and Shimadzu Corporation, Japan. Oscar Rodríguez is grateful to the National Council for Science and Technology (CONACYT, Mexico for the Ph D scholarship 177627.

  19. Reconstruction of Far-Field Tsunami Amplitude Distributions from Earthquake Sources

    Science.gov (United States)

    Geist, Eric L.; Parsons, Tom

    2016-04-01

    The probability distribution of far-field tsunami amplitudes is explained in relation to the distribution of seismic moment at subduction zones. Tsunami amplitude distributions at tide gauge stations follow a similar functional form, well described by a tapered Pareto distribution that is parameterized by a power-law exponent and a corner amplitude. Distribution parameters are first established for eight tide gauge stations in the Pacific, using maximum likelihood estimation. A procedure is then developed to reconstruct the tsunami amplitude distribution that consists of four steps: (1) define the distribution of seismic moment at subduction zones; (2) establish a source-station scaling relation from regression analysis; (3) transform the seismic moment distribution to a tsunami amplitude distribution for each subduction zone; and (4) mix the transformed distribution for all subduction zones to an aggregate tsunami amplitude distribution specific to the tide gauge station. The tsunami amplitude distribution is adequately reconstructed for four tide gauge stations using globally constant seismic moment distribution parameters established in previous studies. In comparisons to empirical tsunami amplitude distributions from maximum likelihood estimation, the reconstructed distributions consistently exhibit higher corner amplitude values, implying that in most cases, the empirical catalogs are too short to include the largest amplitudes. Because the reconstructed distribution is based on a catalog of earthquakes that is much larger than the tsunami catalog, it is less susceptible to the effects of record-breaking events and more indicative of the actual distribution of tsunami amplitudes.

  20. Paleogene volcanism in Central Afghanistan: Possible far-field effect of the India-Eurasia collision

    Science.gov (United States)

    Motuza, Gediminas; Šliaupa, Saulius

    2017-10-01

    A volcanic-sedimentary succession of Paleogene age is exposed in isolated patches at the southern margin of the Tajik block in the Ghor province of Central Afghanistan. The volcanic rocks range from basalts and andesites to dacites, including adakites. They are intercalated with sedimentary rocks deposited in shallow marine environments, dated biostratigraphically as Paleocene-Eocene. This age corresponds to the age of the Asyābēd andesites located in the western Ghor province estimated by the 40Ar/39Ar method as 54 Ma. The magmatism post-dates the Cimmerian collision between the Tajik block (including the Band-e-Bayan block) and the Farah Rod block located to the south. While the investigated volcanic rocks apparently bear geochemical signatures typical to an active continental margin environment, it is presumed that the magmatism was related to rifting processes most likely initiated by far-field tectonics caused by the terminal collision of the Indian plate with Eurasia (Najman et al., 2017). This event led to the dextral movement of the Farah Rod block, particularly along Hari Rod (Herat) fault system, resulting in the development of a transtensional regime in the proximal southern margin of the Tajik block and giving rise to a rift basin where marine sediments were interbedded with pillow lavas intruded by sheeted dyke series.

  1. Mode separation in frequency-wavenumber domain through compressed sensing of far-field Lamb waves

    Science.gov (United States)

    Gao, Fei; Zeng, Liang; Lin, Jing; Luo, Zhi

    2017-07-01

    This method based on Lamb waves shows great potential for long-range damage detection. Mode superposition resulting from multi-modal and dispersive characteristics makes signal interpretation and damage feature extraction difficult. Mode separation in the frequency-wavenumber (f-k) domain using a 1D sparse sensing array is a promising solution. However, due to the lack of prior knowledge about damage location, this method based on 1D linear measurement, for the mode extraction of arbitrary reflections caused by defects that are not in line with the sensor array, is restricted. In this paper, an improved compressed sensing method under the far-field assumption is established, which is beneficial to the reconstruction of reflections in the f-k domain. Hence, multiple components consisting of structure and damage features could be recovered via a limited number of measurements. Subsequently, a mode sweeping process based on theoretical dispersion curves has been designed for mode characterization and direction of arrival estimation. Moreover, 2D f-k filtering and inverse transforms are applied to the reconstructed f-k distribution in order to extract the purified mode of interest. As a result, overlapping waveforms can be separated and the direction of defects can be estimated. A uniform linear sensor array consisting of 16 laser excitations is finally employed for experimental investigations and the results demonstrate the efficiency of the proposed method.

  2. Vectorial Structure of Non-Paraxial Linearly Polarized Gaussian Beam in Far Field

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guo-Quan; CHEN Liang; NI Yong-Zhou

    2006-01-01

    @@ According to the vectorial structure of non-paraxial electromagnetic beams and the method of stationary phase,the analytical TE and TM terms of non-paraxial linearly polarized Gaussian beam are presented in the far field.The influence of linearly polarized angle on the relative energy flux distributions of the whole beam and its TE and TM terms is studied. The beam spot of the TE term is perpendicular to the direction of linearly polarized angle, while that of the TM term coincides with the direction of linearly polarized angle. The whole beam spot is elliptical, and the long axis is located at the direction of linearly polarized angle. The relative energy flux distribution of the TE term is relatively centralized in the direction perpendicular to the linearly polarized angle.While that of the TM term is relatively centralized in the direction of linearly polarized angle. To obtain the isolated TM and TE terms, a polarizer should be put at the long and the short axis of the whole beam. spot,respectively.

  3. ESTIMATION OF FAR-FIELD TSUNAMI POTENTIAL FOR THE CARIBBEAN COAST BASED ON NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Narcisse Zaibo

    2003-01-01

    Full Text Available The tsunami problem for the coast of the Caribbean basin is discussed. Briefly the historical data of tsunami in the Caribbean Sea are presented. Numerical simulation of potential tsunamis in the Caribbean Sea is performed in the framework of the nonlinear-shallow theory. The tsunami wave height distribution along the Caribbean Coast is computed. These results are used to estimate the far-field tsunami potential of various coastal locations in the Caribbean Sea. In fact, five zones with tsunami low risk are selected basing on prognostic computations, they are: the bay “Golfo de Batabano” and the coast of province “Ciego de Avila” in Cuba, the Nicaraguan Coast (between Bluefields and Puerto Cabezas, the border between Mexico and Belize, the bay “Golfo de Venezuela” in Venezuela. The analysis of historical data confirms that there was no tsunami in the selected zones. Also, the wave attenuation in the Caribbean Sea is investigated; in fact, wave amplitude decreases in an order if the tsunami source is located on the distance up to 1000 km from the coastal location. Both factors wave attenuation and wave height distribution should be taken into account in the planned warning system for the Caribbean Sea.

  4. Probabilistic tsunami hazard assessment at Seaside, Oregon, for near-and far-field seismic sources

    Science.gov (United States)

    Gonzalez, F.I.; Geist, E.L.; Jaffe, B.; Kanoglu, U.; Mofjeld, H.; Synolakis, C.E.; Titov, V.V.; Areas, D.; Bellomo, D.; Carlton, D.; Horning, T.; Johnson, J.; Newman, J.; Parsons, T.; Peters, R.; Peterson, C.; Priest, G.; Venturato, A.; Weber, J.; Wong, F.; Yalciner, A.

    2009-01-01

    The first probabilistic tsunami flooding maps have been developed. The methodology, called probabilistic tsunami hazard assessment (PTHA), integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment (PSHA). Application of the methodology to Seaside, Oregon, has yielded estimates of the spatial distribution of 100- and 500-year maximum tsunami amplitudes, i.e., amplitudes with 1% and 0.2% annual probability of exceedance. The 100-year tsunami is generated most frequently by far-field sources in the Alaska-Aleutian Subduction Zone and is characterized by maximum amplitudes that do not exceed 4 m, with an inland extent of less than 500 m. In contrast, the 500-year tsunami is dominated by local sources in the Cascadia Subduction Zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km. The primary sources of uncertainty in these results include those associated with interevent time estimates, modeling of background sea level, and accounting for temporal changes in bathymetry and topography. Nonetheless, PTHA represents an important contribution to tsunami hazard assessment techniques; viewed in the broader context of risk analysis, PTHA provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard, which can then be combined with vulnerability and exposure to yield estimates of tsunami risk. Copyright 2009 by the American Geophysical Union.

  5. Reconstruction of Far-Field Tsunami Amplitude Distributions from Earthquake Sources

    Science.gov (United States)

    Geist, Eric L.; Parsons, Tom

    2016-12-01

    The probability distribution of far-field tsunami amplitudes is explained in relation to the distribution of seismic moment at subduction zones. Tsunami amplitude distributions at tide gauge stations follow a similar functional form, well described by a tapered Pareto distribution that is parameterized by a power-law exponent and a corner amplitude. Distribution parameters are first established for eight tide gauge stations in the Pacific, using maximum likelihood estimation. A procedure is then developed to reconstruct the tsunami amplitude distribution that consists of four steps: (1) define the distribution of seismic moment at subduction zones; (2) establish a source-station scaling relation from regression analysis; (3) transform the seismic moment distribution to a tsunami amplitude distribution for each subduction zone; and (4) mix the transformed distribution for all subduction zones to an aggregate tsunami amplitude distribution specific to the tide gauge station. The tsunami amplitude distribution is adequately reconstructed for four tide gauge stations using globally constant seismic moment distribution parameters established in previous studies. In comparisons to empirical tsunami amplitude distributions from maximum likelihood estimation, the reconstructed distributions consistently exhibit higher corner amplitude values, implying that in most cases, the empirical catalogs are too short to include the largest amplitudes. Because the reconstructed distribution is based on a catalog of earthquakes that is much larger than the tsunami catalog, it is less susceptible to the effects of record-breaking events and more indicative of the actual distribution of tsunami amplitudes.

  6. Far-field method for the characterisation of three-dimensional fields: vectorial polarimetry

    Science.gov (United States)

    Rodríguez, O.; Lara, D.; Dainty, C.

    2010-06-01

    The first attempt to completely characterise a three-dimensional field was done by Ellis and Dogariu with excellent results reported [1] . However, their method is based on near-field techniques, which limits its range of applications. In this work, we present an alternative far-field method for the characterisation of the three-dimensional field that results from the interaction of a tightly focused three-dimensional field [2] with a sub-resolution specimen. Our method is based on the analysis of the scattering-angle-resolved polarisation state distribution across the exit pupil of a high numerical aperture (NA) collector lens using standard polarimetry techniques. Details of the method, the experimental setup built to verify its capabilities, and numerical and first experimental evidence demonstrating that the method allows for high sensitivit y on sub-resolution displacements of a sub-resolution specimen shall be presented [3]. This work is funded by Science Foundation Ireland grant No. 07/IN.1/I906 and Shimadzu Corporation, Japan. Oscar Rodríguez is grateful to the National Council for Science and Technology (CONACYT, Mexico) for the Ph D scholarship 177627.

  7. Prediction of far-field wind turbine noise propagation with parabolic equation.

    Science.gov (United States)

    Lee, Seongkyu; Lee, Dongjai; Honhoff, Saskia

    2016-08-01

    Sound propagation of wind farms is typically simulated by the use of engineering tools that are neglecting some atmospheric conditions and terrain effects. Wind and temperature profiles, however, can affect the propagation of sound and thus the perceived sound in the far field. A better understanding and application of those effects would allow a more optimized farm operation towards meeting noise regulations and optimizing energy yield. This paper presents the parabolic equation (PE) model development for accurate wind turbine noise propagation. The model is validated against analytic solutions for a uniform sound speed profile, benchmark problems for nonuniform sound speed profiles, and field sound test data for real environmental acoustics. It is shown that PE provides good agreement with the measured data, except upwind propagation cases in which turbulence scattering is important. Finally, the PE model uses computational fluid dynamics results as input to accurately predict sound propagation for complex flows such as wake flows. It is demonstrated that wake flows significantly modify the sound propagation characteristics.

  8. Co-authorship patterns and networks of Korean radiation oncologists.

    Science.gov (United States)

    Choi, Jinhyun; Kang, Jin Oh; Park, Seo Hyun; Kim, Sang Ki

    2011-09-01

    This research aimed to analyze the patterns of co-authorship network among the Korean radiation oncologists and to identify attributing factors for the formation of networks. A total of 1,447 articles including contents of 'Radiation Oncology' and 'Therapeutic Radiology' were searched from the KoreaMed database. The co-authorship was assorted by the author's full name, affiliation and specialties. UCINET 6.0 was used to figure out the author's network centrality and the cluster analysis, and KeyPlayer 1.44 program was used to get a result of key player index. Sociogram was analyzed with the Netdraw 2.090. The statistical comparison was performed by a t-test and ANOVA using SPSS 16.0 with p-value articles written by a radiation oncologist as the first author was 1,025 out of 1,447. The pattern of co-authorship was classified into five groups. For articles of which the first author was a radiation oncologist, the number of single-author articles (type-A) was 81; single-institution articles (type-B) was 687; and multiple-author articles (type-C) was 257. For the articles which radiation oncologists participated in as a co-author, the number of single-institution articles (type-D) was 280 while multiple-institution articles (type-E) were 142. There were 8,895 authors from 1,366 co-authored articles, thus the average number of authors per article was 6.51. It was 5.73 for type-B, 6.44 for type-C, 7.90 for type-D, and 7.67 for type-E (p = 0.000) in the average number of authors per article. The number of authors for articles from the hospitals published more than 100 articles was 7.23 while form others was 5.94 (p = 0.005). Its number was 5.94 and 7.16 for the articles published before and after 2001 (p = 0.000). The articles written by a radiation oncologist as the first author had 5.92 authors while others for 7.82 (p = 0.025). Its number was 5.57 and 7.71 for the Journal of the Korean Society for Therapeutic Radiology and Oncology and others (p = 0.000), respectively

  9. Probabilistic Tsunami Hazard in the NE Atlantic from Near- and Far-field Tectonic Sources

    Science.gov (United States)

    Omira, R.; Baptista, M.; Matias, L.; Carrilho, F.; Miranda, J. M.

    2012-12-01

    A comprehensive assessment of the hazard posed by tsunamis must include an evaluation of the possible tsunami impact from near- and far-field sources as well as its likelihood of occurrence. In the NE Atlantic region, tsunami hazard assessment has been mainly performed through deterministic approaches considering regional most credible earthquake scenarios. This work focuses on the probabilistic approach for tsunami hazard assessment in the NE Atlantic region. The advantage of such approach consists of yielding information on the likelihood of tsunami impact in addition to the other components of hazard assessment (wave heights, inundation, run-up…etc). Probabilistic tsunami hazard assessment approach, used here, integrates tsunami waveform and inundation modeling with probabilistic seismic hazard assessment methods. This approach consists of various steps: i) identification of tsunami sources and assessment of their annual rates of recurrence; ii) Numerical simulations of near-shore waveform and flooding; iii) Evaluation of the probability exceedance for wave heights and inundations for a given period of time; vi) Derivation of tsunami hazard curves. Both near- and far-field seismic sources able to trigger tsunamis that reach/affect the NE Atlantic coasts are considered in order to generate a set of credible scenarios for the region. This database incorporates various magnitude ranges of possible earthquakes generated at the potential tsunamigenic zones from the Gulf of Cadiz to the Caribbean. The annual recurrence rate of each magnitude range is derived through the Bayesian method that incorporates seismic information from historical catalog and instrumental periods for the Gulf of Cadiz, while we will use only instrumental information for the Caribbean source area. A numerical code, solving shallow water equations in their linear and non linear forms, is then employed to simulate the tsunami propagation and flooding resulting from the occurrence of the

  10. Sea-level probability for the last deglaciation: A statistical analysis of far-field records

    Science.gov (United States)

    Stanford, J. D.; Hemingway, R.; Rohling, E. J.; Challenor, P. G.; Medina-Elizalde, M.; Lester, A. J.

    2011-12-01

    Pulses of ice-sheet meltwater into the world ocean during the last deglaciation are of great current interest, because these large-scale events offer important test-beds for numerical models of the responses of ocean circulation and climate to meltwater addition. The largest such event has become known as meltwater pulse (mwp) 1a, with estimates of about 20 m of sea-level rise in about 500 years. A second meltwater pulse (mwp-1b) has been inferred from some sea-level records, but its existence has become debated following the presentation of additional records. Even the use of the more ubiquitous mwp-1a in modelling studies has been compromised by debate about its exact age, based upon perceived discrepancies between far-field sea-level records. It is clear that an objective investigation is needed to determine to what level inferred similarities and/or discrepancies between the various deglacial sea-level records are statistically rigorous (or not). For that purpose, we present a Monte Carlo style statistical analysis to determine the highest-probability sea-level history from six key far-field deglacial sea-level records, which fully accounts for realistic methodological and chronological uncertainties in all these records, and which is robust with respect to removal of individual component datasets. We find that sea-level rise started to accelerate into the deglaciation from around 17 ka BP. Within the deglacial rise, there were two distinct increases; one at around the timing of the Bølling warming (14.6 ka BP), and another, much broader, event that just post-dates the end of the Younger Dryas (11.3 ka BP). We interpret these as mwp-1a and mwp-1b, respectively. We find that mwp-1a occurred between 14.3 ka BP and 12.8 ka BP. Highest rates of sea-level rise occurred at ~ 13.8 ka, probably (67% confidence) within the range of 100-130 cm/century, although values may have been as high as 260 cm/century (99% confidence limit). Mwp-1b is robustly expressed as a broad

  11. Linking near- and far-field hydrodynamic models for simulation of desalination plant brine discharges.

    Science.gov (United States)

    Botelho, D A; Barry, M E; Collecutt, G C; Brook, J; Wiltshire, D

    2013-01-01

    A desalination plant is proposed to be the major water supply to the Olympic Dam Expansion Mining project. Located in the Upper Spencer Gulf, South Australia, the site was chosen due to the existence of strong currents and their likely advantages in terms of mixing and dilution of discharged return water. A high-resolution hydrodynamic model (Estuary, Lake and Coastal Ocean Model, ELCOM) was constructed and, through a rigorous review process, was shown to reproduce the intricate details of the Spencer Gulf dynamics, including those characterising the discharge site. Notwithstanding this, it was found that deploying typically adopted 'direct insertion' techniques to simulate the brine discharge within the hydrodynamic model was problematic. Specifically, it was found that in this study the direct insertion technique delivered highly conservative brine dilution predictions in and around the proposed site, and that these were grid and time-step dependent. To improve the predictive capability, a strategy to link validated computational fluid dynamics (CFD) predictions to hydrodynamic simulations was devised. In this strategy, environmental conditions from ELCOM were used to produce boundary conditions for execution of a suite of CFD simulations. In turn, the CFD simulations provided the brine dilutions and flow rates to be applied in ELCOM. In order to conserve mass in a system-wide sense, artificial salt sinks were introduced to the ELCOM model such that salt quantities were conserved. As a result of this process, ELCOM predictions were naturally very similar to CFD predictions near the diffuser, whilst at the same time they produced an area of influence (further afield) comparable to direct insertion methods. It was concluded that the linkage of the models, in comparison to direct insertion methods, constituted a more realistic and defensible alternative to predict the far-field dispersion of outfall discharges, particularly with regards to the estimation of brine

  12. Analytical expressions for group delay in the far field from an optical fiber having an arbitrary index profile

    DEFF Research Database (Denmark)

    Danielsen, Per Lander

    1981-01-01

    A general and efficient model for optical fibers with a few modes and arbitrary index profiles is established. The model yields a solution of the vectorial wave equation and analytical expressions for the group delay and the far field. Convergence tests have shown that the dispersion can be calcu......A general and efficient model for optical fibers with a few modes and arbitrary index profiles is established. The model yields a solution of the vectorial wave equation and analytical expressions for the group delay and the far field. Convergence tests have shown that the dispersion can...

  13. Multiple lobes in the far-field distribution of terahertz quantum-cascade lasers due to self-interference

    Energy Technology Data Exchange (ETDEWEB)

    Röben, B., E-mail: roeben@pdi-berlin.de; Wienold, M.; Schrottke, L.; Grahn, H. T. [Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5–7, 10117 Berlin (Germany)

    2016-06-15

    The far-field distribution of the emission intensity of terahertz (THz) quantum-cascade lasers (QCLs) frequently exhibits multiple lobes instead of a single-lobed Gaussian distribution. We show that such multiple lobes can result from self-interference related to the typically large beam divergence of THz QCLs and the presence of an inevitable cryogenic operation environment including optical windows. We develop a quantitative model to reproduce the multiple lobes. We also demonstrate how a single-lobed far-field distribution can be achieved.

  14. Base Station Antenna Pattern Distortion in Practical Urban Deployment Scenarios

    DEFF Research Database (Denmark)

    Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Sørensen, Troels Bundgaard

    2014-01-01

    In real urban deployments, base station antennas are typically not placed in free space conditions. Therefore, the radiation pattern can be affected by mounting structures and nearby obstacles located in the proximity of the antenna (near-field), which are often not taken into consideration. Also...... the intrinsic propagation mechanisms of the urban environment (far-field) can contribute to the distortion of the radiation pattern observed in a practical deployment scenario, especially when comparing it to the antenna pattern provided by the manufacturer and typically measured in free space. This paper...... presents a combination of near-field and far-field simulations aimed to provide an overview of the distortion experienced by the base station antenna pattern in two different urban deployment scenarios: rooftop and telecommunications tower. The study illustrates how, in comparison with the near...

  15. Change of radiation pattern in a plasma monopole antenna

    Science.gov (United States)

    Siahpoush, V.; Shokri, B.

    2016-07-01

    In the present work, we have numerically solved the dispersion equation of the surface wave propagating on a uniform collisional plasma column. The electric field and surface current distributions have been computed in different situations. We have investigated the effect of plasma frequency variation on the spatial distribution of the surface current. Results show that varying the electron density of the plasma column enables the plasma column to work as a plasma monopole antenna with a fixed geometrical structure and excited frequency which is able to create different radiation patterns. Our numerical analysis also shows that a little change in the radius of the plasma column has a strong influence on the current distribution at the excited frequency in RF region. This effect can be ignored in the usual (metallic) antenna while it is very important in designing of the plasma monopole antenna.

  16. Assessment of reflectivity of noise barriers in the far field – QUIESST method compared to traditional approach

    NARCIS (Netherlands)

    Roo, F. de

    2013-01-01

    The sound reflectivity of noise barriers elements is one of the major acoustic product characteristics. Traditionally this property was tested in reverberation rooms according to EN 1793-1 and the results were used to predict the effect of sound reflections in the far field. As in many cases these r

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

    Institute of Scientific and Technical Information of China (English)

    YANG Zhaoqing; KHANGAOKAR Tarang

    2008-01-01

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

  18. A Patterns of Care Study of the Various Radiation Therapies for Prostate Cancer among Korean Radiation Oncologists in 2006

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hee [Keimyung Univ., Daegu (Korea, Republic of); Kim, Jae Sung; Ha, Sung Whan [Seoul National University College of Medicine, Seoul (Korea, Republic of)] (and others)

    2008-06-15

    To conduct a nationwide academic hospital patterns of the practice status and principles of radiotherapy for prostate cancer. The survey will help develop the framework of a database of Korean in Patterns of Case Study. A questionnaire about radiation treatment status and principles was sent to radiation oncologists in charge of prostate cancer treatment at thirteen academic hospitals in Korea. The data was analyzed to find treatment principles among the radiation oncologists when treating prostate cancer. The number of patients with prostate cancer and treated with radiation ranged from 60 to 150 per academic hospital in Seoul City and 10 to 15 outside of Seoul City in 2006. The primary diagnostic methods of prostate cancer included the ultrasound guided biopsy on 6 to 12 prostate sites (mean=9), followed by magnetic resonance imaging and a whole body bone scan. Internal and external immobilizations were used in 61.5% and 76.9%, respectively, with diverse radiation targets. Whole pelvis radiation therapy (dose ranging from 45.0 to 50.4 Gy) was performed in 76.9%, followed by the irradiation of seminal vesicles (54.0{approx}73.8 Gy) in 92.3%. The definitive radiotherapy doses were increased as a function of risk group, but the range of radiation doses was wide (60.0 to 78.5 Gy). Intensity modulated radiation therapy using doses greater than 70 Gy, were performed in 53.8% of academic hospitals. In addition, the simultaneous intra-factional boost (SIB) technique was used in three hospitals; however, the target volume and radiation dose were diverse. Radiation therapy to biochemical recurrence after a radical prostatectomy was performed in 84.6%; however, the radiation dose was variable and the radiation field ranged from whole pelvis to prostate bed. The results of this study suggest that a nationwide Korean Patterns of Care Study is necessary for the recommendation of radiation therapy guidelines of prostate cancer.

  19. Computation of Far-Field Noise from Vortex Shedding Behind a Circular Cylinder at Low Reynolds Numbers

    Science.gov (United States)

    Choi, H.; You, D.; Choi, M.-R.; Kang, S.-H.

    1996-11-01

    Laminar vortex sheddings behind a circular cylinder with and without splitter plates attached to the cylinder at low Reynolds numbers are simulated by solving the unsteady incompressible Navier-Stokes equations. The Strouhal number, lift and drag rapidly change with the length of the splitter plate. Far-field noise from the vortex shedding behind the cylinder is computed using the Curle's formulation of the Lighthill acoustic analogy. The acoustic source functions are obtained from the computed near-field velocity and pressure. Numerical results show that the volume quadrupole noise is small at a low Mach number, compared to the surface dipole noise from the cylinder. Variations of the far-field noise characteristics with respect to the splitter plate are being investigated and will be shown in the final presentation. ^* Supported by KOSEF under Contract No. 961-1009-075-2

  20. Far-field properties and beam quality of vectorial Hermite-Laguerre-Gaussian beams beyond the paraxial approximation

    Science.gov (United States)

    Kang, Xiaoping; He, Zhong; Lü, Baida

    2007-07-01

    The far-field properties and beam quality of vectorial nonparaxial Hermite-Laguerre-Gaussian (HLG) beams are studied in detail, where, instead of the second-order-moments-based M2 factor, the extended power in the bucket (PIB) and βparameter are used to characterize the beam quality in the far field and the intensity in the formulae is replaced by the z component of the time-averaged Poynting vector . It is found that the PIB and βparameter of vectorial nonparaxial HLG beams depend on the mode indices n, m, αparameter and waist-width-to-wavelength ratio w0/ λ and the PIB and βparameter are additionally dependent on the bucket's size taken.

  1. Spherical-Wave Far-Field Interferometer for Hard X-Ray Phase Contrast Imaging

    CERN Document Server

    Miao, Houxun; Harmon, Katherine J; Bennett, Eric E; Chedid, Nicholas; Panna, Alireza; Bhandarkar, Priya; Wen, Han

    2014-01-01

    Low dose, high contrast x-ray imaging is of general interest in medical diagnostic applications. X-ray Mach-Zehnder interferometers using collimated synchrotron beams demonstrate the highest levels of phase contrast under a given exposure dose. However, common x-ray sources emit divergent cone beams. Here, we developed a spherical-wave inline Mach-Zehnder interferometer for phase contrast imaging over an extended area with a broadband and divergent source. The first tabletop system was tested in imaging experiments of a mammographic accreditation phantom and various biological specimens. The noise level of the phase contrast images at a clinical radiation dose corresponded to a 6 nano radian bending of the x-ray wavefront. Un-resolved structures with conventional radiography and near-field interferometer techniques became visible at a fraction of the radiation dose.

  2. Determination of femtosecond-laser-induced refractive-index changes in an optical fiber from far-field measurements

    DEFF Research Database (Denmark)

    Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul

    2014-01-01

    A new method for direct writing of localized, circularly symmetric refractive-index changes in optical fibers with a femtosecond laser is demonstrated. The refractive-index changes are characterized using a novel approach employing comparison of numerical simulations to the measured far......-field profiles of unmodified and modified fibers. From the analysis, a negative refractive-index change of −0.015 0.005 within a radius of 0.6 0.1 μm is determined....

  3. Optical phase cloaking of 700 nm light waves in the far field by a three-dimensional carpet cloak.

    Science.gov (United States)

    Ergin, Tolga; Fischer, Joachim; Wegener, Martin

    2011-10-21

    Transformation optics is a design tool that connects the geometry of space and propagation of light. Invisibility cloaking is a corresponding benchmark example. Recent experiments at optical frequencies have demonstrated cloaking for the light amplitude only. In this Letter, we demonstrate far-field cloaking of the light phase by interferometric microscope-imaging experiments on the previously introduced three-dimensional carpet cloak at 700 nm wavelength and for arbitrary polarization of light.

  4. Inverse extraction of interfacial tractions from elastic and elasto-plastic far-fields by nonlinear field projection

    Science.gov (United States)

    Chew, Huck Beng

    2013-01-01

    Determining the tractions along a surface or interface from measurement data in the far-fields of nonlinear materials is a challenging inverse problem which has significant engineering and nanoscience applications. Previously, a field projection method was established to identify the crack-tip cohesive zone constitutive relations in an isotropic elastic solid (Hong and Kim, 2003. J. Mech. Phys. Solids 51, 1267). In this paper, the field projection method is further generalized to extracting the tractions along interfaces bounded by nonlinear materials, both with and without pre-existing cracks. The new formulation is based on Maxwell-Betti's reciprocal theorem with a reciprocity gap associated with nonlinear materials. We express the unknown normal and shear tractions along the interface in terms of the Fourier series, and use specially constructed analytical auxiliary fields in the reciprocal theorem to extract the unknown Fourier coefficients from far-field data; the reciprocity gap in the formulation is iteratively determined with a set of numerical algorithms. Our detailed numerical experiments demonstrate that this nonlinear field projection method (NFPM) is well-suited for extracting the interfacial tractions from the far-field data of any nonlinear elastic or elasto-plastic material with known constitutive laws. Applications of the NFPM to experiments and atomistic simulations are discussed.

  5. Phase radiation characteristics of an open-ended circular waveguide

    DEFF Research Database (Denmark)

    Shishkova, Anna; Pivnenko, Sergey; Kim, Oleksiy S.

    2007-01-01

    General analytical expressions are derived for the far-field amplitude and phase radiation patterns of an open-ended circular waveguide (OE-CWG) regardless of its radius or the operation frequency for the dominant and symmetric higher-order excitation modes. The derivation is based on the rigorous...... solution to the problem of diffraction at an open end of a waveguide proposed by Weinstein. The near-field amplitude and phase patterns of an OE-CWG are then calculated using the spherical wave expansion technique. The measurement of the radiation pattern of an OE-CWG was carried out to verify the validity...

  6. Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

    OpenAIRE

    Wu, Yongle; Qu, Meijun; Jiao, Lingxiao; Liu, Yuanan; Ghassemlooy, Zabih

    2016-01-01

    This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical poten...

  7. Thermo-mechanical modeling of continental rift evolution over mantle upwelling in presence of far-field stresses

    Science.gov (United States)

    Koptev, Alexander; Burov, Evgueni; Calais, Eric; Leroy, Sylvie; Gerya, Taras

    2016-04-01

    We conducted fully-coupled high resolution rheologically consistent 3D thermo-mechanical numerical models to investigate the processes of mantle-lithosphere interaction (MLI) in presence of preexisting far-field tectonic stresses. MLI-induced topography exhibits strongly asymmetric small-scale 3D features, such as rifts, flexural flank uplifts and complex faults structures. This suggests a dominant role of continental rheological structure and intra-plate stresses in controlling continental rifting and break-up processes above mantle upwelling while reconciling the passive (far-field tectonic stresses) versus active (plume-activated) rift concepts as our experiments show both processes in action. We tested different experiments by varying two principal controlling parameters: 1) horizontal extension velocity and 2) Moho temperature used as simplified indicator of the thermal and rheological lithosphere layering. An increase in the applied extension expectedly gives less localized deformation at lithospheric scale: the growth of external velocity from 1.5 mm/years to 6 mm/years leads to enlargement of the rift zones from 75-175 km to 150-425 km width. On the contrary, increasing of the lithospheric geotherm has an opposite effect leading to narrowing of the rift zone: the change of the Moho isotherm from 600°C to 800°C causes diminution of the rift width from 175-425 km to 75-150 km. Some of these finding are contra-intuitive in terms of usual assumptions. The models refer to strongly non-linear impact of far-field extension rates on timing of break-up processes. Experiments with relatively fast far-field extension (6 mm/years) show intensive normal fault localization in crust and uppermost mantle above the plume head at 15-20 Myrs after the onset of the experiment. When plume head material reaches the bottom of the continental crust (at 25 Myrs), the latter is rapidly ruptured (crust bottom). We conclude from our modeling that localization of large-scale linear

  8. Radiation pattern of plasmonic nano-antennas in a homogeneous medium.

    Science.gov (United States)

    Sugita, Takafumi; Yanazawa, Kaori; Maeda, Satoshi; Hofmann, Holger F; Kadoya, Yutaka

    2014-06-02

    Radiation patterns from plasmonic nano-antennas formed on a glass substrate were investigated using index-matching oils. It was confirmed that the pattern from single nano-antennas for various cases of index-mismatching between the substrate and the oil is explained well by the patterns of infinitesimal electric dipoles. We found that for an angular resolution of 2°, the index mismatch must be smaller than 0.001 to realize isotropic radiation. By using the appropriate condition, the radiation patterns of nano Yagi-Uda antennas in a quasi-homogeneous medium were obtained experimentally.

  9. Self-similarity in radial Walsh filters and axial intensity distributions in the far-field diffraction pattern.

    Science.gov (United States)

    Mukherjee, P; Hazra, L N

    2014-02-01

    Pupil plane filtering by radial Walsh filters is a convenient technique for tailoring the axial intensity distribution near the focal plane of a rotationally symmetric imaging system. Radial Walsh filters, derived from radial Walsh functions, form a set of orthogonal phase filters that take on values either 0 or π phase, corresponding to +1 or -1 values of the radial Walsh functions over prespecified annular regions of the circular filter. Order of these filters is given by the number of zero-crossings, or equivalently phase transitions within the domain over which the set is defined. In general, radial Walsh filters are binary phase zone plates, each of them demonstrating distinct focusing characteristics. The set of radial Walsh filters can be classified into distinct groups, where the members of each group possess self-similar structures. Self-similarity can also be observed in the corresponding axial intensity distributions. These observations provide valuable clues in tackling the inverse problem of synthesis of phase filter in accordance with prespecified axial intensity distributions. This paper reports our observations on self-similarity in radial Walsh filters of various orders and corresponding axial intensity distributions.

  10. Achieving single-lobed far-field patterns of broad area laser diode with external cavity feedback

    Institute of Scientific and Technical Information of China (English)

    Jianhong Ge(葛剑虹); Jun Chen(陈军); Andreas Hermerschmidt; H.J.Eichler

    2003-01-01

    We demonstrate a technique for single transverse mode operation of high-power broad area laser diode(BAL). In the experiment, the HR mirror is used as an external cavity mirror and the grating is used as a wavelength selective component. By tiling the HR mirror and the grating, the number of transverse modes oscillating in the cavity can be limited and the spectral bandwidth of the laser diode can be reduced. A single-lobed near diffraction-limited laser beam with the beam divergence (FWHM) of 0.43°, the spectral line-width of 0.7 nm and the output power of 350 mW are obtained. With the feedback, the power density of the output laser beam is increased 6 times in comparison with the free running.

  11. Far-Field Testing Method of Spurious Emission Produced by HF RFID

    Directory of Open Access Journals (Sweden)

    Nikola Gvozdenovic

    2016-01-01

    Full Text Available We present measurements of spurious emission produced by high-frequency radio frequency identification (HF RFID using carrier frequency of 13.56 MHz. HF RFID tags produce unwanted emission due to rectification and more generally due to nonlinearity of analog front end. Depending on the conducting material of an HF RFID coil and surrounding dielectric material, the coil behaves as more or less good antenna on some harmonic frequencies. Exact characterization and analysis of unwanted emission is important from the security perspective as well as from the perspective of interference with other systems. Consequently we measured the harmonics produced in the integrated circuitry and characterized radiation properties of the antenna. Finally we present the measurements of the spurious emission performed in a Gigahertz Transverse Electromagnetic (GTEM cell.

  12. Estimation of Near-Field and Far-Field Dilutions for Site Selection of Effluent Outfall in a Coastal Region - A Case Study

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, V.S.

    location for discharge of the effluents into the sea by using near-field and far-field models. Near-field dilutions were calculated using a buoyant jet model, whereas far-field dilutions were estimated using a two-dimensional numerical model. As a case...

  13. Implementation of the far-field method for calculation of added resistance using a high order finite-difference approximation on overlapping grids

    DEFF Research Database (Denmark)

    Amini Afshar, Mostafa; Bingham, Harry B.

    The far-field method for calculation of the wave drift force is implemented in the high order finitedifferenceseakeeping solver. The implementation is based on the Maruo formulation which employesthe Kochin function to obtain the complex amplitude of the velocity potential in the far-field. There...

  14. Ultrabroadband Super-Planckian Radiative Heat Transfer with Profile-Patterned Hyperbolic Metamaterial

    CERN Document Server

    Dai, Jin; Bozhevolnyi, Sergey I; Yan, Min

    2016-01-01

    We demonstrate the possibility of ultrabroadband super-Planckian radiative heat transfer be- tween two metal plates patterned with tapered hyperbolic metamaterial arrays. It is shown that, by employing profile-patterned hyperbolic media, one can design photonic bands to populate a desired thermal radiation window, with a spectral density of modes much higher than what can be achieved with unstructured media. For nanometer-sized gaps between two plates, the modes occupy states both inside and outside the light cone, giving rise to ultrabroadband super-Planckian radiative heat transfer. Our study reveals that structured hyperbolic metamaterial offers unprecedented potential in achieving a controllable super-Planckian radiative heat transfer.

  15. Determination of femtosecond-laser-induced refractive-index changes in an optical fiber from far-field measurements.

    Science.gov (United States)

    Savolainen, Juha-Matti; Grüner-Nielsen, Lars; Kristensen, Poul; Balling, Peter

    2014-06-15

    A new method for direct writing of localized, circularly symmetric refractive-index changes in optical fibers with a femtosecond laser is demonstrated. The refractive-index changes are characterized using a novel approach employing comparison of numerical simulations to the measured far-field profiles of unmodified and modified fibers. From the analysis, a negative refractive-index change of -0.015±0.005 within a radius of (0.6±0.1)  μm is determined.

  16. Towards an optical far-field measurement of higher-order multipole contributions to the scattering response of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Thomas; Orlov, Sergej [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1/Bldg. 24, 91058 Erlangen (Germany); Institute of Optics, Information and Photonics, University Erlangen-Nuremberg, Staudtstr. 7/B2, 91058 Erlangen (Germany); Leuchs, Gerd; Banzer, Peter, E-mail: peter.banzer@mpl.mpg.de [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1/Bldg. 24, 91058 Erlangen (Germany); Institute of Optics, Information and Photonics, University Erlangen-Nuremberg, Staudtstr. 7/B2, 91058 Erlangen (Germany); Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, Ontario K1N 6N5 (Canada)

    2015-03-02

    We experimentally show an all-optical multipolar decomposition of the lowest-order eigenmodes of a single gold nanoprism using azimuthally and radially polarized cylindrical vector beams. By scanning the particle through these tailored field distributions, the multipolar character of the eigenmodes gets encoded into 2D-scanning intensity maps even for higher-order contributions to the eigenmode that are too weak to be discerned in the direct far-field scattering response. This method enables a detailed optical mode analysis of individual nanoparticles.

  17. Metal-dielectric composites for beam splitting and far-field deep sub-wavelength resolution for visible wavelengths.

    Science.gov (United States)

    Yan, Changchun; Zhang, Dao Hua; Zhang, Yuan; Li, Dongdong; Fiddy, M A

    2010-07-05

    We report beam splitting in a metamaterial composed of a silver-alumina composite covered by a layer of chromium containing one slit. By simulating distributions of energy flow in the metamaterial for H-polarized waves, we find that the beam splitting occurs when the width of the slit is shorter than the wavelength, which is conducive to making a beam splitter in sub-wavelength photonic devices. We also find that the metamaterial possesses deep sub-wavelength resolution capabilities in the far field when there are two slits and the central silver layer is at least 36 nm in thickness, which has potential applications in superresolution imaging.

  18. Towards an optical far-field measurement of higher-order multipole contributions to the scattering response of nanoparticles

    CERN Document Server

    Bauer, Thomas; Leuchs, Gerd; Banzer, Peter

    2014-01-01

    We experimentally show an all-optical multipolar decomposition of the lowest-order Eigenmodes of a single gold nanoprism using azimuthally and radially polarized cylindrical vector beams. By scanning the particle through these tailored field distributions, the multipolar character of the Eigenmodes gets encoded into 2D-scanning intensity maps even for higher-order contributions to the Eigenmode that are too weak to be discerned in the direct far-field scattering response. This method enables a detailed optical mode analysis of individual nanoparticles.

  19. Influence of the probe-sample interaction on scanning near-field optical microscopic images in the far field

    Institute of Scientific and Technical Information of China (English)

    Li Zhi; Zhang Jia-Sen; Yang Jing; Gong Qi-Huang

    2006-01-01

    We have studied the influence of probe-sample interaction in a scanning near-field optical microscopy (SNOM) in the far field by using samples with a step structure. For a sample with a step height of ~λ/4, the SNOM image contrast between the two sides of the step changes periodically at different scan heights. For a step height of ~λ/2, the image contrast remains approximately the same. The probe-sample interaction determines the SNOM image contrast here. The influence of different refractive indices of the sample has been also analysed by using a simple theoretical model.

  20. An Algorithm to Calculate Phase-Center Offset of Aperture Antennas when Measuring 2-Dimensional Radiation Patterns

    Science.gov (United States)

    2015-01-01

    An Algorithm to Calculate Phase-Center Offset of Aperture Antennas when Measuring 2-Dimensional Radiation Patterns by Patrick Debroux...Offset of Aperture Antennas when Measuring 2-Dimensional Radiation Patterns Patrick Debroux and Berenice Verdin Survivability/Lethality Analysis... Antennas when Measuring 2-Dimensional Radiation Patterns 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

  1. Far field optical nanoscopy: How far can you go in nanometric characterization without resolving all the details?

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Paul C., E-mail: paul.montgomery@unistra.fr [Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7367, 23 rue du Loess, 67037 Strasbourg (France); Serio, Bruno; Anstotz, Freddy; Montaner, Denis [Laboratoire des Sciences de l’Ingénieur, de l’Informatique et de l’Imagerie (ICube), UDS-CNRS, UMR 7367, 23 rue du Loess, 67037 Strasbourg (France)

    2013-09-15

    In the development of nanomaterials and biomaterials, new characterization techniques are required that overcome the challenges presented by the increasing dimensional ratio between the different entities to be studied and the growing complexity introduced by the use of heterogeneous materials and technologies. Diffraction limited far field optical nanoscopy techniques are receiving growing interest because of their ability to detect nanometer structures over very large fields and at high speed. We present a classification scheme of the different types of optical nanoscopy techniques. In particular, we highlight four categories of far field diffraction limited techniques based on increasing the contrast, measuring the phase, using deconvolution and using nano-markers. We demonstrate that by increasing the power of detectability, observability or measurability, a wealth of information concerning nanometric structures becomes available even though all the lateral details may not be resolved. For example, it is possible to determine the presence, the structure and orientation of nanostructures, to measure their density, position and 2D and 3D distribution and to measure nanometric surface roughness in bulk materials, surfaces, nano-layers, soft matter and cells. These techniques conserve all the advantages associated with classical imaging such as real time imaging, non-invasiveness, non-destructiveness and ease of use.

  2. Introduction of an expert system for the discrimination of local pulmonary vein and atrial far field signals.

    Science.gov (United States)

    Klemm, Hanno Ulrich; Heitzer, Thomas; Ruprecht, Ute; Johnsen, Christin; Meinertz, Thomas; Ventura, Rodolfo

    2010-11-01

    Discrimination of local and far field potentials during sinus rhythm and atrial fibrillation (AF) is essential for successful pulmonary vein (PV) isolation. We sought to introduce an expert system for the classification of electrophysiologic PV signals. For the expert system database, we analyzed ablation procedures of 50 patients with paroxysmal and persistent AF. Standard circumferential catheters and bipolar recordings were required. In a prospective trial, the expert system was compared with the performing electrophysiologists' classifications of potentials during 15 procedures. A total of 1,343 recordings of local PV and far field signals were validated by the sudden disappearance of local potentials during ablation, the presence of dissociated PV activity, and pacing maneuvers. A fast Fourier transform was applied to the individual potentials. Analysis continued in the amplitude and phase representation. Four parameters significant (p expert system correctly predicted their local origin in 86%. An expert system for the evaluation of electrophysiologic signals based on morphology analysis using the Fourier transform is feasible. The ease of use and online availability facilitate a widespread use for AF ablation procedures.

  3. Bridging the terahertz near-field and far-field observations of liquid crystal based metamaterial absorbers

    Science.gov (United States)

    Wang, Lei; Ge, Shijun; Chen, Zhaoxian; Hu, Wei; Lu, Yanqing

    2016-09-01

    Metamaterial-based absorbers play a significant role in applications ranging from energy harvesting and thermal emitters to sensors and imaging devices. The middle dielectric layer of conventional metamaterial absorbers has always been solid. Researchers could not detect the near field distribution in this layer or utilize it effectively. Here, we use anisotropic liquid crystal as the dielectric layer to realize electrically fast tunable terahertz metamaterial absorbers. We demonstrate strong, position-dependent terahertz near-field enhancement with sub-wavelength resolution inside the metamaterial absorber. We measure the terahertz far-field absorption as the driving voltage increases. By combining experimental results with liquid crystal simulations, we verify the near-field distribution in the middle layer indirectly and bridge the near-field and far-field observations. Our work opens new opportunities for creating high-performance, fast, tunable, terahertz metamaterial devices that can be applied in biological imaging and sensing. Project supported by the National Basic Research Program of China (Grant No. 2012CB921803), the National Natural Science Foundation of China (Grants Nos. 61225026, 61490714, 11304151, and 61435008), the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK20150845 and 15KJB140004), the Open Foundation Project of National Laboratory of Solid State Microstructures, China (Grant No. M28003), and the Research Center of Optical Communications Engineering & Technology, Jiangsu Province, China.

  4. The emergence of seismic cycles from stress feedback between intra-plate faulting and far-field tectonic loading

    Science.gov (United States)

    So, Byung-Dal; Capitanio, Fabio A.

    2016-08-01

    Using numerical modeling we show the emergence of cyclic slip behavior of faults from stress feedback through an idealized fault, its surrounding plates and far-field tectonic stress. The tectonic stress is exerted on the fault through a force applied along an idealized plate margin, acting on the fault, resulting from the interactions of viscous embedding and external plates. We find that, in such coupled system, the interaction of plates results into feedback with periodic deformation, slip along the fault and episodic plate margin motions. The viscosity of the embedding and loading plates primarily control the stress-loading time and hence the slip recurrence interval. For an Earth-like range of lithospheric viscosities, we derive a power-law with negative exponent, -0.99 to -0.5, scaling the recurrence period with loading-rate, providing an explanation for the observables from paleoseismology and geodesy. The feedback between single fault and far-field stress that arises from interactions of deforming plates provides a context to understand the earthquake cycle within continents, while reconciling the short-term seismic deformation to the long-term plate tectonics frame.

  5. Simulation of Far-Field Superresolution Fluorescence Imaging with Two-Color One-Photon Excitation of Reversible Photoactivatable Protein

    Institute of Scientific and Technical Information of China (English)

    WANG Chen; QIAO Ling-Ling; MAO Zheng-Le

    2011-01-01

    We propose to achieve far-field super-resolution imaging by using offset two-color one-photon (2C1P) excitation of reversible photoactivatable fluorescence proteins. Due to the distinctive photoswitching performance of the proteins, such as dronpa, the fluorescence emission will only come from the overlapped region of activation beam and excitation beam. The analysis solution of rate equation shows that the resolution of offset 2C1P microscope is "engineered" by laser power of excitation and activation beams and the power ratio between them. Superior lateral and transverse resolution is theoretically demonstrated compared with conventional fluorescence scanning microscopy.%@@ We propose to achieve far-field super-resolution imaging by using offset two-color one-photon(2C1P) excitation of reversible photoactivatable fluorescence proteins.Due to the distinctive photoswitching performance of the proteins,such as dronpa,the fluorescence emission will only come from the overlapped region of activation beam and excitation beam.The analysis solution of rate equation shows that the resolution of offset 2C1P microscope is "engineered" by laser power of excitation and activation beams and the power ratio between them.Superior lateral and transverse resolution is theoretically demonstrated compared with conventional fluorescence scanning microscopy.

  6. The use of antenna radiation pattern in node localisation algorithms for wireless sensor networks

    CSIR Research Space (South Africa)

    Mwila, MK

    2014-08-01

    Full Text Available systems are now deploying directional antennas due to their advantages like energy conservation and better bandwidth utilisation. The study presented by this paper reviews some related works that include the antenna radiation pattern of the sensor node...

  7. Multi-Variable Model-Based Parameter Estimation Model for Antenna Radiation Pattern Prediction

    Science.gov (United States)

    Deshpande, Manohar D.; Cravey, Robin L.

    2002-01-01

    A new procedure is presented to develop multi-variable model-based parameter estimation (MBPE) model to predict far field intensity of antenna. By performing MBPE model development procedure on a single variable at a time, the present method requires solution of smaller size matrices. The utility of the present method is demonstrated by determining far field intensity due to a dipole antenna over a frequency range of 100-1000 MHz and elevation angle range of 0-90 degrees.

  8. Evolutionary patterns and processes in the radiation of phyllostomid bats

    Directory of Open Access Journals (Sweden)

    Monteiro Leandro R

    2011-05-01

    Full Text Available Abstract Background The phyllostomid bats present the most extensive ecological and phenotypic radiation known among mammal families. This group is an important model system for studies of cranial ecomorphology and functional optimisation because of the constraints imposed by the requirements of flight. A number of studies supporting phyllostomid adaptation have focused on qualitative descriptions or correlating functional variables and diet, but explicit tests of possible evolutionary mechanisms and scenarios for phenotypic diversification have not been performed. We used a combination of morphometric and comparative methods to test hypotheses regarding the evolutionary processes behind the diversification of phenotype (mandible shape and size and diet during the phyllostomid radiation. Results The different phyllostomid lineages radiate in mandible shape space, with each feeding specialisation evolving towards different axes. Size and shape evolve quite independently, as the main directions of shape variation are associated with mandible elongation (nectarivores or the relative size of tooth rows and mandibular processes (sanguivores and frugivores, which are not associated with size changes in the mandible. The early period of phyllostomid diversification is marked by a burst of shape, size, and diet disparity (before 20 Mya, larger than expected by neutral evolution models, settling later to a period of relative phenotypic and ecological stasis. The best fitting evolutionary model for both mandible shape and size divergence was an Ornstein-Uhlenbeck process with five adaptive peaks (insectivory, carnivory, sanguivory, nectarivory and frugivory. Conclusions The radiation of phyllostomid bats presented adaptive and non-adaptive components nested together through the time frame of the family's evolution. The first 10 My of the radiation were marked by strong phenotypic and ecological divergence among ancestors of modern lineages, whereas the

  9. Near Field and Far Field Effects in the Taguchi-Optimized Design of AN InP/GaAs-BASED Double Wafer-Fused Mqw Long-Wavelength Vertical-Cavity Surface-Emitting Laser

    Science.gov (United States)

    Menon, P. S.; Kandiah, K.; Mandeep, J. S.; Shaari, S.; Apte, P. R.

    Long-wavelength VCSELs (LW-VCSEL) operating in the 1.55 μm wavelength regime offer the advantages of low dispersion and optical loss in fiber optic transmission systems which are crucial in increasing data transmission speed and reducing implementation cost of fiber-to-the-home (FTTH) access networks. LW-VCSELs are attractive light sources because they offer unique features such as low power consumption, narrow beam divergence and ease of fabrication for two-dimensional arrays. This paper compares the near field and far field effects of the numerically investigated LW-VCSEL for various design parameters of the device. The optical intensity profile far from the device surface, in the Fraunhofer region, is important for the optical coupling of the laser with other optical components. The near field pattern is obtained from the structure output whereas the far-field pattern is essentially a two-dimensional fast Fourier Transform (FFT) of the near-field pattern. Design parameters such as the number of wells in the multi-quantum-well (MQW) region, the thickness of the MQW and the effect of using Taguchi's orthogonal array method to optimize the device design parameters on the near/far field patterns are evaluated in this paper. We have successfully increased the peak lasing power from an initial 4.84 mW to 12.38 mW at a bias voltage of 2 V and optical wavelength of 1.55 μm using Taguchi's orthogonal array. As a result of the Taguchi optimization and fine tuning, the device threshold current is found to increase along with a slight decrease in the modulation speed due to increased device widths.

  10. Comment on "Swarming Ring Patterns in Bacterial Colonies Exposed to Ultraviolet Radiation"

    CERN Document Server

    Ordemann, A; Ordemann, Anke; Moss, Frank

    2002-01-01

    Commenting on the paper "Swarming Ring Patterns in Bacterial Colonies Exposed to Ultraviolet Radiation" of A.M. Delprato et al., Phys. Rev. Lett 87, 158102 (2001) we point out that their observed ring pattern formation by colonies of soil bacteria Bacillus subtilis exposed to ultra violet (UV) radiation might be caused by the artificial confinement of motile bacteria evolved to live in a 3-dimensional environment to a 2-dimensional geometry. We propose that to investigate the reaction of Bacillus subtilis to UV radiation coming from above, a seminal experiment should have a 3-dimensional setup.

  11. Near-Field Resonance at Far-Field Anti-Resonance: Plasmonically Enhanced Light Emission with Minimum Scattering Nanoantennas

    CERN Document Server

    Rodriguez, S R K; Lozano, G; Omari, A; Hens, Z; Rivas, J Gomez

    2012-01-01

    We demonstrate that a periodic array of optical antennas sustains a resonant Near-Field (NF) and an anti-resonant Far-Field (FF) at the same energy and in-plane momentum. This phenomenon arises in the context of coupled plasmonic lattice resonances, whose bright and dark character is interchanged at a critical antenna length. The energies of these modes anti-cross in the FF, but cross in the NF. Hence, we observe an extremely narrow bandwidth emission enhancement from quantum dots in the proximity of the array, while the antennas scatter minimally into the FF. Simulations reveal that a standing wave with a quadrupolar field distribution is the origin of this dark collective resonance.

  12. Deep geodynamics of far field intercontinental back-arc extension:Formation of Cenozoic volcanoes in northeastern China

    Institute of Scientific and Technical Information of China (English)

    石耀霖; 张健

    2004-01-01

    There are three cases of variation of trench location possible to occur during subduction: trench fixed, trench advancing, and trench retreating. Retreat of trench may lead to back-arc extension. The Pacific plate subducts at low angle beneath the Eurasia plate, tomographic results indicate that the subducted Pacific slab does not penetrate the 670 km discontinuity, instead, it is lying flat above the interface. The flattening occurred about 28 Ma ago. Geodynamic computation suggests: when the frontier of the subducted slab reaches the phase boundary of lower and upper mantle, it may be hindered and turn flat lying above the boundary, facilitates the retreat of trench and back-arc extension. Volcanism in northeastern China is likely a product of such retreat of subduction, far field back-arc extension, and melting due to reduce of pressure while mantle upwelling.

  13. Far-field linear optical superresolution via heterodyne detection in a higher-order local oscillator mode

    CERN Document Server

    Yang, Fan; Moiseev, E S; Simon, Christoph; Lvovsky, A I

    2016-01-01

    The Rayleigh limit has so far applied to all microscopy techniques that rely on linear optical interaction and detection in the far field. Here we demonstrate that detecting the light emitted by an object in higher-order transverse electromagnetic modes (TEMs) can help achieving sub-Rayleigh precision for a variety of microscopy-related tasks. Using optical heterodyne detection in TEM01, we measure the position of coherently and incoherently emitting objects to within 0.0015 and 0.012 of the Rayleigh limit, respectively, and determine the distance between two incoherently emitting slits positioned within 0.28 of the Rayleigh limit with a precision of 0.019 of the Rayleigh limit. Extending our technique to higher-order TEMs enables full imaging with resolution significantly below the Rayleigh limit in a way that is reminiscent of quantum tomography of optical states.

  14. The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered. By neglecting the interface energy, interface kinetics and buoyancy effects in the system, we obtaine the steady-state solution for the case of the large Schmidt number, in terms of the multiple variable expansion method. The changes of the temperature and concentration fields, the morphology of the interface, the normalization parameter and the Peclet number of the system induced by uniform external flow are derived. The results show that, compared with the system of dendritic growth from undercooled pure melt, the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface. Nevertheless, the shape of the interface still remains nearly a paraboloid.

  15. The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

    Institute of Scientific and Technical Information of China (English)

    CHEN MingWen; WANG ZiDong; XU JianJun

    2009-01-01

    The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered.By neglecting the interface energy,interface kinetics and buoyancy effects in the system,we obtaine the steady-state solution for the case of the large Schmidt number,in terms of the multiple variable expansion method.The changes of thtemperature and concentration fields,the morphology of the interface,the normalization parameter and the Peclet number of the system induced by uniform external flow are derived.The results show that,compared with the system of dendritic growth from undercooled pure melt,the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface.Nevertheless,the shape of the interface still remains nearly a paraboloid.

  16. Testing the near field/far field model performance for prediction of particulate matter emissions in a paint factory

    DEFF Research Database (Denmark)

    Koivisto, A.J.; Jensen, A.C.Ø.; Levin, Marcus

    2015-01-01

    A Near Field/Far Field (NF/FF) model is a well-accepted tool for precautionary exposure assessment but its capability to estimate particulate matter (PM) concentrations is not well studied. The main concern is related to emission source characterization which is not as well defined for PM emitters...... compared to e.g. for solvents. One way to characterize PM emission source strength is by using the material dustiness index which is scaled to correspond to industrial use by using modifying factors, such as handling energy factors. In this study we investigate how well the NF/FF model predicts PM...... concentration levels in a paint factory. PM concentration levels were measured during big bag and small bag powder pouring. Rotating drum dustiness indices were determined for the specific powders used and applied in the NF/FF model to predict mass concentrations. Modeled process specific concentration levels...

  17. Simulating seasonal patterns of increased greenhouse crop production by conversion of direct radiation into diffuse radiation

    NARCIS (Netherlands)

    Jongschaap, R.E.E.; Dueck, T.A.; Hemming, S.; Marcelis, L.F.M.; Marissen, A.

    2006-01-01

    The conversion of direct solar photosynthetically active radiation (PARDir) into diffuse radiation (PARDif) and its effects on greenhouse crop production were analyzed with simulation models. PARDir can be converted into PARDif by increasing the haze of greenhouse covers with a minimal loss of radia

  18. Two-dimensional circulation and mixing in the far field of a surface-advected river plume

    Science.gov (United States)

    Mazzini, Piero L. F.; Chant, Robert J.

    2016-06-01

    Field observations of the Hudson River plume are presented to discuss circulation and mixing in the far field of this coastally trapped buoyant flow. The plume was surface advected and propagated downshelf near the internal wave speed. The plume outflow was characterized by a two-layer bulge-like feature but became continuously stratified and vertically sheared in the far field, where Richardson numbers are generally below 0.5. High-frequency velocity and backscatter data from a moored ADCP revealed strong vertical and horizontal oscillatory motions at the front with a wavelength approximately 7-8 times the plume thickness, consistent with Kelvin-Helmholtz instabilities. These motions quickly died out after 2-3 cycles. The combination of vertical shear and stratification in the plume leads to a buoyancy flux toward the nose of the plume, which competes with mixing. However, the continued salinity increase of the plume as it propagated downshelf indicates that mixing overcomes this delivery of freshwater to the plume front. A simple 2-D model is developed, which relates the time rate-of-change of the plume salinity to: (1) salt entrainment due to vertical mixing, and (2) freshwater flux and salt removal due to the vertical shear of the stratified plume. Estimates of an entrainment coefficient from this model are consistent with previous estimates from the near field of a river outflow. A scaling of the plume width is obtained by assuming that vertical shears are controlled by both thermal wind and a critical Richardson number. This scaling yields plume widths that are consistent with previous laboratory studies.

  19. Out of band radiation effects on resist patterning

    Energy Technology Data Exchange (ETDEWEB)

    George, Simi A .; Naulleau, Patrick P.

    2011-03-11

    Our previous work estimated the expected out-of-band (OOB) flare contribution at the wafer level assuming that there is a given amount of OOB at the collector focus. We found that the OOB effects are wavelength, resist, and pattern dependent. In this paper, results from rigorous patterning evaluation of multiple OOB-exposed resists using the SEMATECH Berkeley 0.3-NA MET are presented. A controlled amount of OOB is applied to the resist films before patterning is completed with the MET. LER and process performance above the resolution limit and at the resolution limits are evaluated and presented. The results typically show a negative impact on LER and process performance after the OOB exposures except in the case of single resist formulation, where resolution and performance improvement was observed.

  20. The Effects of Landcover Pattern on Urban Surface Net Radiation Retrieved by Remote Sensing

    Science.gov (United States)

    Zhao, X.

    2015-12-01

    Taking Xiamen city as the study area, this research retrieved surface net radiation using meteorological data and Landsat 5 TM images of the four seasons in the year 2009. Meanwhile the 65 different landscape metrics of each analysis unit were acquired using landscape analysis method. Then the most effective landscape metrics affecting surface net radiation were determined by correlation analysis, partial correlation analysis, stepwise regression method, etc. At both class and landscape levels, this paper comprehensively analyzed the temporal and spatial variations of the surface net radiation as well as the effects of land cover pattern on it in Xiamen from a multi-seasonal perspective. The results showed that: Xiamen's surface net radiation is the maximum in summer, followed by spring, autumn. The surface net radiation in winter is the minimum. Net radiation flux is higher for water and forestland and is lower for built-up land and bare land, etc. The spatial composition of land cover pattern shows significant influence on surface net radiation. The proportion of bare land and the proportion of forest land are effective and important factors which affect the changes of surface net radiation all the year round. But the spatial allocation of land cover pattern has no significant influence on surface net radiation. Moreover, the proportion of forest land is more capable for explaining surface net radiation than the proportion of bare land. Its total annual explanatory ability is better than the latter. So the proportion of forest land is the most important and continuously effective factor which affects and explains the cross-seasonal differences of surface net radiation. This study is helpful in exploring the formation and evolution mechanism of urban heat island. It also gave theoretical hints and realistic guidance for urban planning and sustainable development.

  1. Improved Modeling of Open Waveguide Aperture Radiators for use in Conformal Antenna Arrays

    Science.gov (United States)

    Nelson, Gregory James

    Open waveguide apertures have been used as radiating elements in conformal arrays. Individual radiating element model patterns are used in constructing overall array models. The existing models for these aperture radiating elements may not accurately predict the array pattern for TEM waves which are not on boresight for each radiating element. In particular, surrounding structures can affect the far field patterns of these apertures, which ultimately affects the overall array pattern. New models of open waveguide apertures are developed here with the goal of accounting for the surrounding structure effects on the aperture far field patterns such that the new models make accurate pattern predictions. These aperture patterns (both E plane and H plane) are measured in an anechoic chamber and the manner in which they deviate from existing model patterns are studied. Using these measurements as a basis, existing models for both E and H planes are updated with new factors and terms which allow the prediction of far field open waveguide aperture patterns with improved accuracy. These new and improved individual radiator models are then used to predict overall conformal array patterns. Arrays of open waveguide apertures are constructed and measured in a similar fashion to the individual aperture measurements. These measured array patterns are compared with the newly modeled array patterns to verify the improved accuracy of the new models as compared with the performance of existing models in making array far field pattern predictions. The array pattern lobe characteristics are then studied for predicting fully circularly conformal arrays of varying radii. The lobe metrics that are tracked are angular location and magnitude as the radii of the conformal arrays are varied. A constructed, measured array that is close to conforming to a circular surface is compared with a fully circularly conformal modeled array pattern prediction, with the predicted lobe angular locations and

  2. Relationship Between Landcover Pattern and Surface Net Radiation in AN Coastal City

    Science.gov (United States)

    Zhao, X.; Liu, L.; Liu, X.; Zhao, Y.

    2016-06-01

    Taking Xiamen city as the study area this research first retrieved surface net radiation using meteorological data and Landsat 5 TM images of the four seasons in the year 2009. Meanwhile the 65 different landscape metrics of each analysis unit were acquired using landscape analysis method. Then the most effective landscape metrics affecting surface net radiation were determined by correlation analysis, partial correlation analysis, stepwise regression method, etc. At both class and landscape levels, this paper comprehensively analyzed the temporal and spatial variations of the surface net radiation as well as the effects of land cover pattern on it in Xiamen from a multi-seasonal perspective. The results showed that the spatial composition of land cover pattern shows significant influence on surface net radiation while the spatial allocation of land cover pattern does not. The proportions of bare land and forest land are effective and important factors which affect the changes of surface net radiation all the year round. Moreover, the proportion of forest land is more capable for explaining surface net radiation than the proportion of bare land. So the proportion of forest land is the most important and continuously effective factor which affects and explains the cross-seasonal differences of surface net radiation. This study is helpful in exploring the formation and evolution mechanism of urban heat island. It also gave theoretical hints and realistic guidance for urban planning and sustainable development.

  3. RELATIONSHIP BETWEEN LANDCOVER PATTERN AND SURFACE NET RADIATION IN AN COASTAL CITY

    Directory of Open Access Journals (Sweden)

    X. Zhao

    2016-06-01

    Full Text Available Taking Xiamen city as the study area this research first retrieved surface net radiation using meteorological data and Landsat 5 TM images of the four seasons in the year 2009. Meanwhile the 65 different landscape metrics of each analysis unit were acquired using landscape analysis method. Then the most effective landscape metrics affecting surface net radiation were determined by correlation analysis, partial correlation analysis, stepwise regression method, etc. At both class and landscape levels, this paper comprehensively analyzed the temporal and spatial variations of the surface net radiation as well as the effects of land cover pattern on it in Xiamen from a multi-seasonal perspective. The results showed that the spatial composition of land cover pattern shows significant influence on surface net radiation while the spatial allocation of land cover pattern does not. The proportions of bare land and forest land are effective and important factors which affect the changes of surface net radiation all the year round. Moreover, the proportion of forest land is more capable for explaining surface net radiation than the proportion of bare land. So the proportion of forest land is the most important and continuously effective factor which affects and explains the cross-seasonal differences of surface net radiation. This study is helpful in exploring the formation and evolution mechanism of urban heat island. It also gave theoretical hints and realistic guidance for urban planning and sustainable development.

  4. The Effective Radiation Pattern Concept for Realistic Performance Estimation of LTE Wireless Systems

    Directory of Open Access Journals (Sweden)

    Dimitra Zarbouti

    2013-01-01

    Full Text Available Radio channels induce distortions to the radiation pattern of beamforming systems such as beam broadening as well as sidelobe level and null rising. If these effects are ignored, the system performance is overestimated. This paper proposes the simple concept of an effective radiation pattern (ERP calculated by optimally fitting the “real-world” radiation pattern to the ERP. The proposed ERP method is incorporated into a multicell bad urban 4G LTE operational scenario which employs beamforming for both the BSs and the RNs. The performed simulations provide evidence that the ideal instead of the real radiation pattern overestimates the SIR and capacity by almost 3 dB and 13 Mbps, respectively, for the reference scenario without RNs. It also proves that the ERP method produces almost identical performance results with the real radiation pattern, and hence it is a simple and viable option for realistic performance analysis. Finally, the network performance is studied as a function of the number of RNs with the help of the ERP method. Results show that a beamforming LTE network with RNs that also employ beamforming provides 3 dB SIR gain with the addition of 1 RN per cell and 15 dB gain with 4 RNs per cell.

  5. IONIC LIQUIDS: RADIATION CHEMISTRY, SOLVATION DYNAMICS AND REACTIVITY PATTERNS.

    Energy Technology Data Exchange (ETDEWEB)

    WISHART,J.F.

    2007-10-01

    energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Methods. Picosecond pulse radiolysis studies at BNL

  6. Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

    Energy Technology Data Exchange (ETDEWEB)

    Wishart, J.F.

    2011-06-12

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs generally have low volatilities and are combustion-resistant, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of primary radiation chemistry, charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of reactions and product distributions. We study these issues by characterization of primary radiolysis products and measurements of their yields and reactivity, quantification of electron solvation dynamics and scavenging of electrons in different states of solvation. From this knowledge we wish to learn how to predict radiolytic mechanisms and control them or mitigate their effects on the properties of materials used in nuclear fuel processing, for example, and to apply IL radiation chemistry to answer questions about general chemical reactivity in ionic liquids that will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that the slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increase the importance of pre-solvated electron reactivity and consequently alter product distributions and subsequent chemistry. This difference from conventional solvents has profound effects on predicting and controlling radiolytic yields

  7. Generation of a reference radiation pattern of string instruments using automatic excitation and acoustic centering.

    Science.gov (United States)

    Shabtai, Noam R; Behler, Gottfried; Vorländer, Michael

    2015-11-01

    Radiation patterns of musical instruments are important for the understanding of music perception in concert halls, and may be used to improve the plausibility of virtual acoustic systems. Many attempts have been performed to measure the spatial response of musical instruments using surrounding spherical microphone arrays with a limited number of microphones. This work presents a high-resolution spatial sampling of the radiation pattern of an electrically excited violin, and addresses technical problems that arise due to mechanical reasons of the excitation apparatus using acoustic centering.

  8. Control of the Radiation Patterns Using Homogeneous and Isotropic Impedance Metasurface

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2015-01-01

    Full Text Available We propose to control the radiation patterns of a two-dimensional (2D point source by using impedance metasurfaces. We show that the radiation patterns can be manipulated by altering the surface impedance of the metasurface. Full-wave simulation results are provided to validate the theoretical derivations. The proposed design enjoys novel properties of isotropy, homogeneity, low profile, and high selectivity of frequency, making it potentially applicable in many applications. We also point out that this design can be implemented with active metasurfaces and the surface impedance can be tuned by modulating the value of loaded elements, like resistors, inductors, and capacitors.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  10. A Planar Reconfigurable Radiation Pattern Dipole Antenna with Reflectors and Directors for Wireless Communication Applications

    Directory of Open Access Journals (Sweden)

    Imen Ben Trad

    2014-01-01

    Full Text Available A planar printed dipole antenna with reflectors and directors, able to steer its radiation pattern in different directions, is proposed for telecommunication applications. Starting from a dual-beam printed dipole antenna achieved by combining two elementary dipoles back to back, and by loading four PIN diodes, three modes of reconfigurable radiation patterns are achieved at the frequency 2.56 GHz thanks to switches states. A prototype of the structure was realized and characterized; an efficiency of 75% is obtained. Simulation and measured results of the results are presented and discussed.

  11. Seismic fragility analysis of typical pre-1990 bridges due to near- and far-field ground motions

    Science.gov (United States)

    Mosleh, Araliya; Razzaghi, Mehran S.; Jara, José; Varum, Humberto

    2016-03-01

    Bridge damages during the past earthquakes caused several physical and economic impacts to transportation systems. Many of the existing bridges in earthquake prone areas are pre-1990 bridges and were designed with out of date regulation codes. The occurrences of strong motions in different parts of the world show every year the vulnerability of these structures. Nonlinear dynamic time history analyses were conducted to assess the seismic vulnerability of typical pre-1990 bridges. A family of existing concrete bridge representative of the most common bridges in the highway system in Iran is studied. The seismic demand consists in a set of far-field and near-field strong motions to evaluate the likelihood of exceeding the seismic capacity of the mentioned bridges. The peak ground accelerations (PGAs) were scaled and applied incrementally to the 3D models to evaluate the seismic performance of the bridges. The superstructure was assumed to remain elastic and the nonlinear behavior in piers was modeled by assigning plastic hinges in columns. In this study the displacement ductility and the PGA are selected as a seismic performance indicator and intensity measure, respectively. The results show that pre-1990 bridges subjected to near-fault ground motions reach minor and moderate damage states.

  12. Antenna Gain Far Field Testing and Calibration%天线增益远场测试及标定

    Institute of Scientific and Technical Information of China (English)

    束咸荣; 董玉良; 王华; 郭先松

    2012-01-01

    The modified Friis transmission formula is put forward in this paper. Based on this, the engineering processing formulas on antenna gain 5 far field test methods are obtained. This analysis points out that, antenna gain test by"the comparative law"is no use for think about insertion loss of test cables and calculating distance between transmitting antenna and receiving antenna, thus it is conveniently for apply to engineering. At last the gain theory curves of different 5 pyramidal homs are calculated with 3 methods and advice on standard-gain horn correct design and exact calibration is given.%文中提出了改进的Friis传输公式,据此得到天线增益远场测试5种方法的工程处理公式.分析指出,其中“比较法”测量天线增益不需要考虑测试馈线的插入损耗和提供收、发天线的间距,便于工程应用.最后,以3种方法计算5种规格角锥喇叭增益的理论曲线,给出了标准增益喇叭正确设计和精确标定的建议.

  13. Far field R-wave sensing in Myotonic Dystrophy type 1: right atrial appendage versus Bachmann's bundle region lead placement.

    Science.gov (United States)

    Russo, Vincenzo; Nigro, Gerardo; Antonio Papa, Andrea; Rago, Anna; Di Meo, Federica; Cristiano, Anna; Molino, Antonio; Calabrò, Raffaele; Giovanna Russo, Maria; Politano, Luisa

    2014-10-01

    Aim of the present study was to investigate far field R-wave sensing (FFRS) timing and characteristics in 34 Myotonic Dystrophy type 1 (DM1) patients undergoing dual chamber pacemaker implantation, comparing Bachmann's bundle (BB) stimulation (16 patients) site with the conventional right atrial appendage (RAA) pacing site (18 patients). All measurements were done during sinus rhythm and in supine position, with unipolar (UP) and bipolar (BP) sensing configuration. The presence, amplitude threshold (FFRS trsh) and FFRS timing were determined. There were no differences between both atrial sites in the Pmin and Pmean values of sensed P-wave amplitudes, as well as between UP and BP sensing configurations. The FFRS trsh was lower at the BB region in comparison to the RAA site. The mean BP FFRS trsh was significantly lower than UP configuration in both atrial locations. There were no significant differences in atrial pacing threshold, sensing threshold and atrial lead impedances at the implant time and at FFRS measurements. Bachmann's bundle area is an optimal atrial lead position for signal sensing as well as conventional RAA, but it offers the advantage of reducing the oversensing of R-wave on the atrial lead, thus improving functioning of standard dual chamber pacemakers in DM1 patients.

  14. USAF bioenvironmental noise data handbook. Volume 172: Hush-noise suppressor (Aero Systems Engineering, Incorporated) far-field noise

    Science.gov (United States)

    Lee, R. A.; Rau, T. H.; Jones, C.

    1982-07-01

    The hush-house noise suppressor was made by Aero Systems Engineering of Texas, Inc. for acoustical suppression of various AF fighter/trainer aircraft during ground runup operations. This report provides measured and extrapolated data defining the bioacoustic environments produced by several aircraft/engines operating in the hush-house suppressor for various engine power configurations. Far-field data measured at 20 locations are normalized to standard meteorological conditions and extrapolated from 75-8000 meters to derive sets of equal-value contours for seven acoustic measures as function of angle and distance from the source. Refer to Volume 1 of this handbook, 'USAF Bioenvironmental Noise Data Handbook, Vol 1: Organization, Content and Application,' AMRL-TR-75(1) 1975, for discussion of the objective and design of the handbook, the types of data presented, measurement procedures, instrumentation, data processing, definitions of quantities, symbols, equations, applications, limitations, etc. Data are presented for the following aircraft/engines operating in the hush-house noise suppressor: F-4, F-15, F-16, F-105, F-106, F-111F and T-38 aircraft and the TF41-A-1, J79-GE-15, F100-PW-100, J75-P19, J-75-P-17 and TF30-P-100 engines.

  15. Near- and far-field scattering from arbitrary three-dimensional aggregates of coated spheres using parallel computing.

    Science.gov (United States)

    Boyde, Lars; Chalut, Kevin J; Guck, Jochen

    2011-02-01

    Many scientific fields--including astronomy, climatology, and biology, among others--require the calculation of the scattered optical fields from multiparticle distributions. In the present study, we combine the established results for the scattering from clusters of homogeneous spheres and from single core-shell particles into a computationally tractable solution that is valid for irregular configurations of nonidentical, coated particles. The presented multiparticle scattering (MPS) model is based on a generalized Lorenz-Mie theory framework and the vector translation theorems for the vector spherical harmonics. We provide the MPS model in both the near and far fields, and for plane-wave and Gaussian beam illumination. A message-passing-interface protocol is used for the computational implementation of the model in a parallel computer program. The computer model is validated by verifying the accuracy of the vector translation theorems utilized in our theoretical methods and by qualitative comparison to existing multiparticle scattering data. We conclude by presenting the scattering profiles from several examples of particle distributions. This MPS model is a practicable method of calculating the optical fields arising in the scattering from particle aggregates and is straightforwardly extensible to arbitrary illumination and to more complex internal-particle structures, such as stratified spheres. Vital applications of this model include the exact computation of forces exerted on irregular objects in optical traps and the simulation of light propagation through biological tissues.

  16. Theoretical and numerical studies of crack initiation and propagation in rock masses under freezing pressure and far-field stress

    Directory of Open Access Journals (Sweden)

    Yongshui Kang

    2014-10-01

    Full Text Available Water-bearing rocks exposed to freezing temperature can be subjected to freeze–thaw cycles leading to crack initiation and propagation, which are the main causes of frost damage to rocks. Based on the Griffith theory of brittle fracture mechanics, the crack initiation criterion, propagation direction, and crack length under freezing pressure and far-field stress are analyzed. Furthermore, a calculation method is proposed for the stress intensity factor (SIF of the crack tip under non-uniformly distributed freezing pressure. The formulae for the crack/fracture propagation direction and length of the wing crack under freezing pressure are obtained, and the mechanism for coalescence of adjacent cracks is investigated. In addition, the necessary conditions for different coalescence modes of cracks are studied. Using the topology theory, a new algorithm for frost crack propagation is proposed, which has the capability to define the crack growth path and identify and update the cracked elements. A model that incorporates multiple cracks is built by ANSYS and then imported into FLAC3D. The SIFs are then calculated using a FISH procedure, and the growth path of the freezing cracks after several calculation steps is demonstrated using the new algorithm. The proposed method can be applied to rocks containing fillings such as detritus and slurry.

  17. Optimization of Fixed Microphone Array in High Speed Train Noises Identification Based on Far-Field Acoustic Holography

    Directory of Open Access Journals (Sweden)

    Rujia Wang

    2017-01-01

    Full Text Available Acoustical holography has been widely applied for noise sources location and sound field measurement. Performance of the microphones array directly determines the sound source recognition method. Therefore, research is very important to the performance of the microphone array, its array of applications, selection, and how to design instructive. In this paper, based on acoustic holography moving sound source identification theory, the optimization method is applied in design of the microphone array, we select the main side lobe ratio and the main lobe area as the optimization objective function and then put the optimization method use in the sound source identification based on holography, and finally we designed this paper to optimize microphone array and compare the original array of equally spaced array with optimization results; by analyzing the optimization results and objectives, we get that the array can be achieved which is optimized not only to reduce the microphone but also to change objective function results, while improving the far-field acoustic holography resolving effect. Validation experiments have showed that the optimization method is suitable for high speed trains sound source identification microphone array optimization.

  18. Far-field correlation of bidirectional tracking beams due to wave-front deformation in inter-satellites optical communication links.

    Science.gov (United States)

    Yu, Siyuan; Ma, Zhongtian; Ma, Jing; Wu, Feng; Tan, Liying

    2015-03-23

    In some applications of optical communication systems, such as inter-satellites optical communication, the correlation of the bidirectional tracking beams changes in far-field as a result of wave-front deformation. Far-field correlation model with wave-front deformation on tracking stability is established. Far-field correlation function and factor have been obtained. Combining with parameters of typical laser communication systems, the model is corrected. It shows that deformation pointing-tracking errors θ(A) and θ(B), far-field correlation factor δ depend on RMS of deformation error rms, which decline with a increasing rms including Tilt and Coma. The principle of adjusting far-field correlation factor with wave-front deformation to compensate deformation pointing-tracking errors has been given, through which the deformation pointing-tracking error is reduced to 18.12″ (Azimuth) and 17.65″ (Elevation). Work above possesses significant reference value on optimization design in inter-satellites optical communication.

  19. Radiation pattern synthesis of planar antennas using the iterative sampling method

    Science.gov (United States)

    Stutzman, W. L.; Coffey, E. L.

    1975-01-01

    A synthesis method is presented for determining an excitation of an arbitrary (but fixed) planar source configuration. The desired radiation pattern is specified over all or part of the visible region. It may have multiple and/or shaped main beams with low sidelobes. The iterative sampling method is used to find an excitation of the source which yields a radiation pattern that approximates the desired pattern to within a specified tolerance. In this paper the method is used to calculate excitations for line sources, linear arrays (equally and unequally spaced), rectangular apertures, rectangular arrays (arbitrary spacing grid), and circular apertures. Examples using these sources to form patterns with shaped main beams, multiple main beams, shaped sidelobe levels, and combinations thereof are given.

  20. Radiation pattern synthesis of planar antennas using the iterative sampling method

    Science.gov (United States)

    Stutzman, W. L.; Coffey, E. L.

    1975-01-01

    A synthesis method is presented for determining an excitation of an arbitrary (but fixed) planar source configuration. The desired radiation pattern is specified over all or part of the visible region. It may have multiple and/or shaped main beams with low sidelobes. The iterative sampling method is used to find an excitation of the source which yields a radiation pattern that approximates the desired pattern to within a specified tolerance. In this paper the method is used to calculate excitations for line sources, linear arrays (equally and unequally spaced), rectangular apertures, rectangular arrays (arbitrary spacing grid), and circular apertures. Examples using these sources to form patterns with shaped main beams, multiple main beams, shaped sidelobe levels, and combinations thereof are given.

  1. Frequency-dependent radiation patterns emitted by THz plasmons on finite length cylindrical metal wires

    NARCIS (Netherlands)

    Deibel, J.A.; Berndsen, N.; Wang, K.; Mittleman, D.M.; Van der Valk, N.C.J.; Planken, P.C.M.

    2006-01-01

    We report on the emission patterns from THz plasmons propagating towards the end of cylindrical metal waveguides. Such waveguides exhibit low loss and dispersion, but little is known about the dynamics of the terahertz radiation at the end of the waveguide, specifically in the near- and intermediate

  2. Changes in Handset Performance Measures due to Spherical Radiation Pattern Measurement Uncertainty

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ødum; Pedersen, Gert Frølund

    An important characteristic of a mobile handset is its ability to receive and transmit power. One way to characterize the performance of a handset in this respect is to use measurements of the spherical radiation pattern from which the total radiated power (TRP), total isotropic sensitivity (TIS......), and mean effective gain (MEG) can be computed. Often this kind of measurements are made with a phantom head next to the handsets in order to simulate the influence of a real user. The measured radiation patterns are only expected to be repeatable if the same setup is used, i.e., the same phantom...... and the same mounting of the handset on the phantom. In this work the influence of mounting errors on the TRP, TIS, and MEG is investigated. Knowledge about the error due to incorrect mounting is necessary in determining requirements for both the mounting accuracy as well as for other parts of the measurement...

  3. A FDTD solution of scattering of laser beam with orbital angular momentum by dielectric particles: Far-field characteristics

    Science.gov (United States)

    Sun, Wenbo; Hu, Yongxiang; Weimer, Carl; Ayers, Kirk; Baize, Rosemary R.; Lee, Tsengdar

    2017-02-01

    Electromagnetic (EM) beams with orbital angular momentum (OAM) may have great potential applications in communication technology and in remote sensing of the Earth-atmosphere system and outer planets. Study of their interaction with optical lenses and dielectric or metallic objects, or scattering of them by particles in the Earth-atmosphere system, is a necessary step to explore the advantage of the OAM EM beams. In this study, the 3-dimensional (3D) scattered-field (SF) finite-difference time domain (FDTD) technique with the convolutional perfectly matched layer (CPML) absorbing boundary conditions (ABC) is applied to calculate the scattering of the purely azimuthal (the radial mode number is assumed to be zero) Laguerre-Gaussian (LG) beams with the OAM by dielectric particles. We found that for OAM beam's interaction with dielectric particles, the forward-scattering peak in the conventional phase function (P11) disappears, and light scattering peak occurs at a scattering angle of 15° to 45°. The disappearance of forward-scattering peak means that, in laser communications most of the particle-scattered noise cannot enter the receiver, thus the received light is optimally the original OAM-encoded signal. This feature of the OAM beam also implies that in lidar remote sensing of the atmospheric particulates, most of the multiple-scattering energy will be off lidar sensors, and this may result in an accurate profiling of particle layers in the atmosphere or in the oceans by lidar, or even in the ground when a ground penetration radar (GPR) with the OAM is applied. This far-field characteristics of the scattered OAM light also imply that the optical theorem, which is derived from plane-parallel wave scattering case and relates the forward scattering amplitude to the total cross section of the scatterer, is invalid for the scattering of OAM beams by dielectric particles.

  4. Plane-polar Fresnel and far-field computations using the Fresnel-Wilcox and Jacobi-Bessel expansions. [for large aperture antennas

    Science.gov (United States)

    Rahmat-Samii, Y.; Galindo-Israel, V.

    1981-01-01

    It is pointed out that the computation of the Fresnel fields for large aperture antennas is significant for many applications. The present investigation is concerned with an approach for the effective utilization of the coefficients of the Jacobi-Bessel series for the far-field to obtain an analytically continuous representation of the antenna field which is valid from the Fresnel region into the far field. Attention is given to exact formulations and closed form solutions, Fresnel and Fresnel small angle approximations, aspects of field expansion, the accuracy of the Fresnel and Fresnel small angle approximations, and the Jacobi-Bessel expansion applied to the Fresnel small angle approximation.

  5. Evidence for mobile phone radiation exposure effects on reproductive pattern of male rats: role of ROS.

    Science.gov (United States)

    Kesari, Kavindra Kumar; Behari, Jitendra

    2012-09-01

    The relationship between radiofrequency electromagnetic fields emitted from mobile phone and infertility is a matter of continuing debate. It is postulated that these radiations may affect the reproduction pattern spell by targeting biochemistry of sperm. In an attempt to expedite the issue, 70 days old Wistar rats (n = 6) were exposed to mobile phone radiofrequency (RF) radiation for 2 h per day for 45 days and data compared with sham exposed (n = 6) group. A significant decrease (P rats showed significant decreases in number and weight as compared with that of sham-exposed animals. A reduction in testosterone, an increase in caspase-3, and distortion in spermatozoa could be caused by overproduction of reactive oxygen species (ROS) in animals under mobile phone radiation exposure. Our findings on these biomarkers are clear indications of possible health implications of repeated exposure to mobile phone radiation.

  6. Reirradiation after radical radiation therapy: a survey of patterns of practice among Canadian radiation oncologists.

    Science.gov (United States)

    Joseph, Kurian Jones; Al-Mandhari, Zahid; Pervez, Nadeem; Parliament, Matthew; Wu, Jackson; Ghosh, Sunita; Tai, Patricia; Lian, Jidong; Levin, Wilfred

    2008-12-01

    The objective of this study was to survey the use of reirradiation (Re-RT) for in-field failures after previous radical radiation treatment (RT) among Canadian radiation oncologists (ROs). An electronic survey was sent to 271 ROs in Canada. The completed surveys were received electronically via e-mail and the data were analyzed using SAS 9.1.3 software. A total of 183 ROs (67.5%) completed and returned the survey. The majority of the respondents were involved in the practice of either breast (48%) or genitourinary (43%) tumor sites. A total of 49% of the participants were interested in using Re-RT for the management of in-field recurrences. The goals of the therapy would be improvement of quality of life (99%), locoregional control (80%), or cure (32%). Most of the physicians believed that patients should have a minimum Karnofsky performance status of 50 or Eastern Cooperative Oncology Group performance status of 3, a minimum life expectancy of 3 months, and a minimum interval from initial treatment of 3 months if Re-RT were to be given with curative intent. This survey showed that a wide variation existed among ROs in their approach to Re-RT. Newer technologies in RT planning and delivery would be employed to facilitate normal tissue avoidance. The results of this study suggested that a consensus meeting was needed to establish guidelines for the practice and prospective evaluation of Re-RT.

  7. Nanoscale displacement of the image of an atomic source of radiation

    Institute of Scientific and Technical Information of China (English)

    Xin Li; Jie Shu; Henk F. Arnoldus

    2009-01-01

    Light emitted by an atomic source of radiation appears to travel along a straight line (ray) from the location of the source to the observer in the far field. However, when the energy flow pattern of the radiation is resolved with an accuracy better than an optical wavelength, it turns out that the field lines are usually curved. We consider electric dipole radiation, a prime example of which is the radiation emitted by an atom during an electronic transition, and we show that the field lines of energy flow are in general curves. Near the location of the dipole, the field lines exhibit a vortex structure, and in the far field they approach a straight line. The spatial extension of the vortex in the optical near field is of nanoscale dimension. Due to the rotation of the field lines near the source, the asymptotic limit of a field line is not exactly in the radially outward direction and as a consequence, the image in the far field is slightly shifted. This sub-wavelength displacement of the image of the source should be amenable to experimental observation with contemporary nanoscale-precision techniques.

  8. 2.5D far-field diffraction tomography inversion scheme for GPR that takes into account the planar air-soil interface

    DEFF Research Database (Denmark)

    Meincke, Peter

    2001-01-01

    A new 2.5D inversion scheme is derived for fixed-offset ground penetrating radar (GPR) that takes into account the planar air-soil interface. The inversion scheme is based upon the first Born approximation and a far-field approximation of the dyadic Green function for a two-layer medium....

  9. Comparison between a near-field and a far-field indexing approach for characterization of a polycrystalline sample volume containing more than 1500 grains

    NARCIS (Netherlands)

    Nervo, L.; King, A.; Wright, J.P.; Ludwig, W.; Reischig, P.; Quinta da Fonseca, J.; Preuss, M.

    2014-01-01

    A comparison of the performance of X-ray diffraction tomography, a near-field diffraction technique, and a far-field diffraction technique for indexing X-ray diffraction data of polycrystalline materials has been carried out by acquiring two sets of diffraction data from the same polycrystalline sam

  10. MARFA version 3.2.2 user's manual: migration analysis of radionuclides in the far field

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Scott; Mancillas, James (Center for Nuclear Waste Regulatory Analyses, Southwest Research Inst., San Antonio, TX (United States))

    2009-12-15

    The computer code Migration Analysis of Radionuclides in the Far Field (MARFA) uses a particle-based Monte Carlo method to simulate the transport of radionuclides in a sparsely fractured geological medium. Transport in sparsely fractured rock is of interest because this medium may serve as a barrier to migration of radionuclides to the accessible environment. The physical processes represented in MARFA include advection, longitudinal dispersion, Fickian diffusion into an infinite or finite rock matrix, equilibrium sorption, decay, and in-growth. Multiple non-branching decay chains of arbitrary length are supported. This document describes the technical basis and input requirements for MARFA Version 3.2.2. MARFA Version 3.2 included new capabilities to accommodate transient flow velocities and sorption parameters, which are assumed to be piecewise constant in time. Version 3.2.1 was a minor change from Version 3.2 to allow a more convenient input format for sorption information. New capabilities in Version 3.2.2 include an option to specify a non-zero start time for the simulation, an optional input parameter that decreases the amount of retention within a single fracture because of flow channeling, and an alternative method for sampling the radionuclide source. MARFA uses the particle on random streamline segment algorithm/Painter et al. 2006/, a Monte Carlo algorithm combining time-domain random walk methods with pathway stochastic simulation. The algorithm uses non-interacting particles to represent packets of radionuclide mass. These particles are moved through the system according to rules that mimic the underlying physical transport and retention processes. The set of times required for particles to pass through the geological barrier are then used to reconstruct discharge rates (mass or activity basis). Because the algorithm uses non-interacting particles, the transport and retention processes are limited to those that depend linearly on radionuclide

  11. Ultrabroadband super-Planckian radiative heat transfer with artificial continuum cavity states in patterned hyperbolic metamaterials

    Science.gov (United States)

    Dai, Jin; Ding, Fei; Bozhevolnyi, Sergey I.; Yan, Min

    2017-06-01

    Localized cavity resonances due to nanostructures at material surfaces can greatly enhance radiative heat transfer (RHT) between two closely placed bodies owing to stretching of cavity states in momentum space beyond the light line. Based on such understanding, we numerically demonstrate the possibility of ultrabroadband super-Planckian RHT between two plates patterned with trapezoidal-shaped hyperbolic metamaterial (HMM) arrays. The phenomenon is rooted not only in HMM's high effective index for creating subwavelength resonators but also its extremely anisotropic isofrequency contour. The two properties enable one to create photonic bands with a high spectral density to populate a desired thermal radiation window. At submicron gap sizes between such two plates, the artificial continuum states extend outside the light cone, tremendously increasing overall RHT. Our study reveals that structured HMM offers unprecedented potential in achieving a controllable super-Planckian radiative heat transfer for thermal management at nanoscale.

  12. Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yongle, E-mail: wuyongle138@gmail.com; Qu, Meijun; Jiao, Lingxiao; Liu, Yuanan [School of Electronic Engineering, Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, P. O. Box. 282, Beijing, 100876 (China); Ghassemlooy, Zabih [Optical Communications Research Group, NCRLab, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne, NE1 8ST (United Kingdom)

    2016-06-15

    This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in different positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.

  13. Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

    Directory of Open Access Journals (Sweden)

    Yongle Wu

    2016-06-01

    Full Text Available This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in different positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.

  14. A dual-band reconfigurable Yagi-Uda antenna with diverse radiation patterns

    Science.gov (United States)

    Saurav, Kushmanda; Sarkar, Debdeep; Srivastava, Kumar Vaibhav

    2017-07-01

    In this paper, a dual-band pattern reconfigurable antenna is proposed. The antenna comprises of a dual-band complementary split ring resonators (CSRRs) loaded dipole as the driven element and two copper strips with varying lengths as parasitic segments on both sides of the driven dipole. PIN diodes are used with the parasitic elements to control their electrical length. The CSRRs loading provide a lower order mode in addition to the reference dipole mode, while the parasitic elements along with the PIN diodes are capable of switching the omni-directional radiation of the dual-band driven element to nine different configurations of radiation patterns which include bi-directional end-fire, broadside, and uni-directional end-fire in both the operating bands. A prototype of the designed antenna together with the PIN diodes and DC bias lines is fabricated to validate the concept of dual-band radiation pattern diversity. The simulation and measurement results are in good agreement. The proposed antenna can be used in wireless access points for PCS and WLAN applications.

  15. Characterization of coherent Cherenkov radiation source

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, A.V.

    2015-01-21

    Engineering formulae for calculation of peak, and spectral brightness of resonant long-range wakefield extractor are given. It is shown that the brightness is dominated by beam density in the slow wave structure and antenna gain of the outcoupling. Far field radiation patterns and brightness of circular and high aspect ratio planar radiators are compared. A possibility to approach diffraction limited brightness is demonstrated. The role of group velocity in designing of the Cherenkov source is analyzed. The approach can be applied for design and characterization of various structure-dominated sources (e.g., wakefield extractors with gratings or dielectrics, or FEL-Cherenkov combined sources) radiating into a free space using an antenna (in microwave to sub-mm wave regions). The high group velocity structures can be also effective as energy dechirpers and for diagnostics of microbunched relativistic electron beams.

  16. The stratigraphic imprint of a mid-Telychian (Llandovery, Early Silurian glaciation on far-field shallow-water carbonates, Anticosti Island, Eastern Canada

    Directory of Open Access Journals (Sweden)

    François Clayer

    2014-12-01

    Full Text Available The near-field stratigraphic record of the Early Silurian glaciations is well documented in the literature. Data from far-field areas are, however, sparse. One of the best far-field stratigraphic records of these Llandovery glaciations is exposed on Anticosti Island in eastern Canada. Eight shallow-water paleotropical facies are present close to the mid-Telychian Jupiter–Chicotte formational boundary along the south-central coast of Anticosti Island. These can be grouped into three facies associations that include, from bottom to top: a carbonate facies association (FA-1, a mixed siliciclastic and carbonate facies association (FA-2 and an encrinitic facies association (FA-3. These mid- to outer-ramp strata represent deposition mostly from episodic, high-energy storm events as evidenced by their sharp bases, hummocky cross-stratification, large wave ripples, gutter casts and wave-enhanced sediment gravity flow deposits. Superimposed on a long-term regressive trend, one main transgressive–regressive (TR sequence and four meter-scale TR cycles are evident, indicating a multi-order stratigraphic framework developed under the influence of glacio-eustasy. The Jupiter–Chicotte formational boundary, a regional discontinuity surface caused by a forced regression, corresponds to the onset of a far-field mid-Telychian glaciation.

  17. On the Seismic Response of Protected and Unprotected Middle-Rise Steel Frames in Far-Field and Near-Field Areas

    Directory of Open Access Journals (Sweden)

    Dora Foti

    2014-01-01

    Full Text Available Several steel moment-resisting framed buildings were seriously damaged during Northridge (1994; Kobe (1995; Kocaeli, Turkey (1999, earthquakes. Indeed, for all these cases, the earthquake source was located under the urban area and most victims were in near-field areas. In fact near-field ground motions show velocity and displacement peaks higher than far-field ones. Therefore, the importance of considering near-field ground motion effects in the seismic design of structures is clear. This study analyzes the seismic response of five-story steel moment-resisting frames subjected to Loma Prieta (1989 earthquake—Gilroy (far-field register and Santa Cruz (near-field register. The design of the frames verifies all the resistance and stability Eurocodes’ requirements and the first mode has been determined from previous shaking-table tests. In the frames two diagonal braces are installed in different positions. Therefore, ten cases with different periods are considered. Also, friction dampers are installed in substitution of the braces. The behaviour of the braced models under the far-field and the near-field records is analysed. The responses of the aforementioned frames equipped with friction dampers and subjected to the same ground motions are discussed. The maximum response of the examined model structures with and without passive dampers is analysed in terms of damage indices, acceleration amplification, base shear, and interstory drifts.

  18. Effect of the tank main gun on the radiation pattern of the monopole antenna

    Directory of Open Access Journals (Sweden)

    Miroslav Lj. Đorđević

    2011-01-01

    Full Text Available For telecommunication purposes, a monopole antenna is usually positioned on the tank turret. At low frequencies the whole tank has to be treated as a part of the antenna system. In this paper a method for electromagnetic modeling of metallic structures is presented and applied to the analysis of radiation of a tank monopole antenna. Radiation simulations are performed at the frequency range from 1MHz to 30MHz. A special attention is given to the analysis of the effects of increased elevation of the tank main gun to the radiation pattern of the antenna. The analysis of the radiation of the tank monopole is performed with and without the presence of conducting ground. It is shown that the increase in the main gun elevation at certain frequencies can lead to degradation of uniformity of radiation in the horizontal plane. Introduction Informational technologies and reliable and secure communications are an important part of a modern military doctrine. Regarding telecommunications, armored vehicles and tanks in particular present a specific problem. In this paper, a theoretical basis of the electromagnetic analysis of metallic structures and a modeling technique will be presented. The effect of the tank on the radiation pattern will be investigated both for a tank in free space and above the conducting ground. Method of moments The method of moments (MoM is a method for an approximate solution of integral equations. This section presents the fundamentals of the MoM and the higher-order quadrilaterals as the basic elements used for geometry modeling. The currents in our method are approximated using high-order two-dimensional polynomials. Modeling of the tank geometry The tank is modeled using only 28 elements, out of which 10 bilinear quadrilaterals and 18 second-order surfaces. The monopole antenna is modeled using one straight wire segment. Results The use of the polynomial current approximation yields a reduction in the number of unknowns required

  19. On applicability of the far-field approximation to the analysis of light scattering by particulate media

    Science.gov (United States)

    Tishkovets, Victor P.; Petrova, Elena V.

    2016-10-01

    Problems of the theory of light scattering by densely packed discrete random media are analyzed with the model, considering such medium as a semi-infinite layer composed of randomly oriented clusters. Each of the clusters is assumed to be in the far zones of all other clusters. Under this approach, the numerical solution of the radiative transfer equation and the equation for weak localization of waves yields the characteristics of radiation reflected by the medium. Since in these equations an elementary volume of the medium is assumed to be represented by randomly oriented clusters, the near-field effects, as well as the irregular shape and heterogeneity of the scatterers, are partially taken into account. The model results are compared to the currently available laboratory measurements of the intensity and the degree of linear polarization of nonabsorbing samples (MgO, Al2O3, and SiO2) composed the scatterers smaller than the wavelength in size. The scattering characteristics of the samples with different (though not very high) packing densities are considered. In the frames of the applied model, some of the calculated phase profiles of polarization well agree with the measured ones. This allowed us to estimate the relative concentration of scatterers in the media and their sizes. At the same time, the measured phase dependences of intensity are poorly fitted with the models. This suggests that some scattering mechanisms remained beyond the frames the considered model; these mechanisms noticeably influence the intensity of radiation reflected by the medium, while their effect on the linear polarization is negligible.

  20. Utilisation of Symmetry Properites for the Pattern Analysis of Mutually Coupled Patch Radiators

    Directory of Open Access Journals (Sweden)

    M. Gimersky

    1992-05-01

    Full Text Available The influence of mutual coupling effects on the radiation pattern of microstrip antennas is investigated by introducing symmetry properties in the surface current distributions. The standard method of moments is used, which requires only the upper half of three x— and y— direction offset patch radiators to be solved, while the symmetric lower half is incorporated after the determination of the current distribution. Furthermore, the Toeplitz symmetry of the impedance matrix is taken into account, and the singular value decomposition is used to invert the resulting non-square matrix in a numerically stable way. Both the symmetry property and the Toeplitz symmetry procedures reduce storage and CPU-time requirements in the analysis of broadside microstrip arrays. The pattern characteristics calculated with and without mutual coupling interactions are found to differ up to 10 dB in sideloge levels which clearly demonstrates that the pattern can be as severely affected by mutual coupling as the commonly investigated input impedance. The predicted results are in good agreement with measured data on single patches.

  1. Topography and Radiative Forcing Patterns on Glaciers in the Karakoram Himalaya

    Science.gov (United States)

    Dobreva, I. D.; Bishop, M. P.; Liu, J. C.; Liang, D.

    2015-12-01

    Glaciers in the western Himalaya exhibit significant spatial variations in morphology and dynamics. Climate, topography and debris cover variations are thought to significantly affect glacier fluctuations and glacier sensitivity to climate change, although the role of topography and radiative forcing have not been adequately characterized and related to glacier fluctuations and dynamics. Consequently, we examined the glaciers in the Karakoram Himalaya, as they exhibit high spatial variability in glacier fluctuation rates and ice dynamics including flow velocity and surging. Specifically, we wanted to examine the relationships between these glacier characteristics and temporal patterns of surface irradiance over the ablation season. To accomplish this, we developed and used a rigorous GIS-based solar radiative transfer model that accounts for the direct and diffuse-skylight irradiance components. The model accounts for multiple topographic effects on the magnitude of irradiance reaching glacier surfaces. We specifically used the ASTER GDEM digital elevation model for irradiance simulations. We then examined temporal patterns of irradiance at the grid-cell level to identify the dominant patterns that were used to train a 3-layer artificial neural network. Our results demonstrate that there are unique spatial and temporal patterns associated with downwasting and surging glaciers, and that these patterns partially account for the spatial distribution of advancing and retreating glaciers. Lower-altitude terminus regions of surging glaciers exhibited relatively low surface irradiance values that decreased in magnitude with time, demonstrating that high-velocity surging glaciers facilitate relief production and exhibit steeper surface irradiance gradients with altitude. Collectively, these results demonstrate the important role that local and regional topography play in governing climate-glacier dynamics in the Himalaya.

  2. Polarization and Radiation Pattern Reconfigurability of a Planar Monopole-Fed Loop Antenna for GPS Application

    Directory of Open Access Journals (Sweden)

    M. M. Fakharian

    2016-12-01

    Full Text Available This paper presents a reconfigurable loop antenna with monopole-fed using embedded RF PIN switches based shorted parasitic elements for GPS applications. The antenna can independently reconfiguring multiple polarizations with switchable radiation pattern. Four switched metallic patches are used as parasitic elements to provide a reconfiguration capability to antenna acting as a driven monopole-fed loop. The edge of the parasitic elements is shorted by posts. The parasitic patches are connected/disconnected by using switching, therewith changing the configuration of monopole, to turn changes the current distribution over the loop surface. The antenna is designed to work on the GPS L1 frequency band. The antenna simultaneously changes the radiation beam in E- and H-planes, and switches among three polarizations (LP, LHCP, and RHCP in the various modes. The antenna maximum gain among the different modes is tuned between 1.5 and 4.2 dBi.

  3. Anatomical exposure patterns of skin to sunlight: relative contributions of direct, diffuse and reflected ultraviolet radiation.

    Science.gov (United States)

    Vernez, D; Milon, A; Vuilleumier, L; Bulliard, J-L

    2012-08-01

    The dose-response between ultraviolet (UV) exposure patterns and skin cancer occurrence is not fully understood. Sun-protection messages often focus on acute exposure, implicitly assuming that direct UV radiation is the key contributor to the overall UV exposure. However, little is known about the relative contribution of the direct, diffuse and reflected radiation components. To investigate solar UV exposure patterns at different body sites with respect to the relative contribution of the direct, diffuse and reflected radiation. A three-dimensional numerical model was used to assess exposure doses for various body parts and exposure scenarios of a standing individual (static and dynamic postures). The model was fed with erythemally weighted ground irradiance data for the year 2009 in Payerne, Switzerland. A year-round daily exposure (08:00-17:00 h) without protection was assumed. For most anatomical sites, mean daily doses were high (typically 6.2-14.6 standard erythemal doses) and exceeded the recommended exposure values. Direct exposure was important during specific periods (e.g. midday during summer), but contributed moderately to the annual dose, ranging from 15% to 24% for vertical and horizontal body parts, respectively. Diffuse irradiation explained about 80% of the cumulative annual exposure dose. Acute diffuse exposures were also observed during cloudy summer days. The importance of diffuse UV radiation should not be underestimated when advocating preventive measures. Messages focused on avoiding acute direct exposures may be of limited efficiency to prevent skin cancers associated with chronic exposure. © 2012 The Authors. BJD © 2012 British Association of Dermatologists.

  4. Optical gaps, mode patterns and dipole radiation in two-dimensional aperiodic photonic structures

    Science.gov (United States)

    Boriskina, Svetlana V.; Gopinath, Ashwin; Negro, Luca Dal

    2009-05-01

    Based on the rigorous generalized Mie theory solution of Maxwell's equations for dielectric cylinders we theoretically investigate the optical properties of two-dimensional deterministic structures based on the Fibonacci, Thue-Morse and Rudin-Shapiro aperiodic sequences. In particular, we investigate bandgap formation and mode localization properties in aperiodic photonic structures based on the accurate calculation of their local density of states (LDOS). In addition, we explore the potential of photonic structures based on aperiodic order for the engineering of radiative rates and emission patterns in erbium-doped silicon-rich nitride photonic structures.

  5. International Patterns of Practice in the Management of Radiation Therapy-induced Nausea and Vomiting

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, Kristopher; Zhang Liying [Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada); Lutz, Stephen [Blanchard Valley Health Systems, Findlay, Ohio (United States); Baardwijk, Angela van [Department of Radiation Oncology (MAASTRO Clinic), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht (Netherlands); Linden, Yvette van der [Leiden University Medical Center, Leiden (Netherlands); Holt, Tanya [Radiation Oncology Mater Centre, Princess Alexandra Hospital, Brisbane (Australia); Arnalot, Palmira Foro [Parc de Salut Mar. Universitat Pompeu Fabra Barcelona (Spain); Lagrange, Jean-Leon [AP-HP Hopital Henri-Mondor, Universite Paris Est Creteil, Creteil (France); Maranzano, Ernesto [' S. Maria' Hospital, Terni (Italy); Liu, Rico [Queen Mary Hospital, Hong Kong (China); Wong, Kam-Hung [Queen Elizabeth Hospital, Hong Kong (Hong Kong); Wong, Lea-Choung [National University Cancer Institute (Singapore); Vassiliou, Vassilios [Bank of Cyprus Oncology Centre, Nicosia (Cyprus); Corn, Benjamin W. [Tel Aviv Medical Center, Tel Aviv (Israel); De Angelis, Carlo; Holden, Lori; Wong, C. Shun [Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada); Chow, Edward, E-mail: Edward.Chow@sunnybrook.ca [Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada)

    2012-09-01

    Purpose: To investigate international patterns of practice in the management of radiation therapy-induced nausea and vomiting (RINV). Methods and Materials: Oncologists prescribing radiation therapy in the United States, Canada, The Netherlands, Australia, New Zealand, Spain, Italy, France, Hong Kong, Singapore, Cyprus, and Israel completed a Web-based survey that was based on 6 radiation therapy-only clinical cases modeled after the minimal-, low-, moderate-, and high-emetic risk levels defined in the antiemetic guidelines of the American Society of Clinical Oncology and the Multinational Association of Supportive Care in Cancer. For each case, respondents estimated the risks of nausea and vomiting separately and committed to an initial management approach. Results: In total, 1022 responses were received. Risk estimates and management decisions for the minimal- and high-risk cases varied little and were in line with guideline standards, whereas those for the low- and moderate-risk cases varied greatly. The most common initial management strategies were as follows: rescue therapy for a minimal-risk case (63% of respondents), 2 low-risk cases (56% and 80%), and 1 moderate-risk case (66%); and prophylactic therapy for a second moderate-risk case (75%) and a high-risk case (95%). The serotonin (5-HT){sub 3} receptor antagonists were the most commonly recommended prophylactic agents. On multivariate analysis, factors predictive of a decision for prophylactic or rescue therapy were risk estimates of nausea and vomiting, awareness of the American Society of Clinical Oncology antiemetic guideline, and European Society for Therapeutic Radiology and Oncology membership. Conclusions: Risk estimates and management strategies for RINV varied, especially for low- and moderate-risk radiation therapy cases. Radiation therapy-induced nausea and vomiting are under-studied treatment sequelae. New observational and translational studies are needed to allow for individual patient risk

  6. Dual Strip-Excited Dielectric Resonator Antenna with Parasitic Strips for Radiation Pattern Reconfigurability

    Directory of Open Access Journals (Sweden)

    M. Kamran Saleem

    2014-01-01

    Full Text Available A novel pattern reconfigurable antenna concept utilizing rectangular dielectric resonator antenna (DRA placed over dielectric substrate backed by a ground plane is presented. A dual strip excitation scheme is utilized and both excitation strips are connected together by means of a 50 Ω microstrip feed network placed over the substrate. The four vertical metallic parasitic strips are placed at corner of DRA each having a corresponding ground pad to provide a short/open circuit between the parasitic strip and antenna ground plane, through which a shift of 90° in antenna radiation pattern in elevation plane is achieved. A fractional bandwidth of approximately 40% at center frequency of 1.6 GHz is achieved. The DRA peak realized gain in whole frequency band of operation is found to be above 4 dB. The antenna configuration along with simulation and measured results are presented.

  7. Giant Magnetostrictive Material Loudspeaker System Acoustic Radiation Simulation

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; ZHANG Yong-fa

    2008-01-01

    An infinite panel model of giant magnetostrictive material loudspeaker system (GMMLS) is proposed by making use of finite element method(FEM). Bending wave eigenfunction is introduced to describe the acoustic radiation condition of the panel. Far-field response in different conditions is calculated by changing the mass surface density. Conclusion is obtained by analyzing the curves simulated, that panel which has larger mass surface density can hardly generate far-field acoustic radiation for lower frequency, while the panel has smaller mass surface density generates far-field acoustic radiation for lower frequency evenly and stronger.

  8. Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

    Science.gov (United States)

    Teperik, Tatiana V.; de Lustrac, André

    2015-12-01

    We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.

  9. Spine Metastasis Practice Patterns among Korean, Chinese, and Japanese Radiation Oncologists: A Multinational Online Survey Study

    Science.gov (United States)

    Yu, Jeong Il; Park, Hee Chul; Ahn, Yong Chan; Gao, Xian-Shu; Wang, Jun-Jie; Zeng, Zhao-Chong; Ito, Yoshinori; Ohno, Tatsuya; Nishimura, Yasumasa

    2017-01-01

    This online survey of practising radiation oncologists from Korea, China and Japan was conducted to investigate the current practices in radiotherapy (RT) for spine metastasis and to compare these practices across the three countries. The questionnaire included nine general information questions and two clinical scenarios (representing ‘typical’ and ‘good’ prognosis spine metastasis), with seven questions for each scenario. An anonymous web-based survey using Google Docs® was undertaken from 2 September 2014 to 9 April 2015. A total of 54 Korean, 107 Chinese and 104 Japanese radiation oncologists participated in the study. The first scenario involved a typical case of spine metastasis (~25% expected 1-year survival rate), and the preferred fractionation scheme was 10 fractions of 3 Gy, though the pattern was slightly different in each country. The second scenario involved a good prognosis case (>50% expected 1-year survival rate), and 10 fractions of 3 Gy was the preferred practice in all three countries (however, use of a larger fraction dose with a smaller fraction number was more common in Korea). A more conformal RT technique was more prominent in China and Korea, especially for patients with a good prognosis. Avoidance of reirradiation was notable in China. In summary, a preference for multiple fractionation in RT for spine metastasis was observed in the majority of Korean, Chinese and Japanese radiation oncologists, although there were slight differences in practice preferences, especially for patients with a favorable prognosis. PMID:27672099

  10. Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

    Energy Technology Data Exchange (ETDEWEB)

    Teperik, Tatiana V., E-mail: tatiana.teperik@u-psud.fr [Univ. Paris-Sud, Institut d’Electronique Fondamentale, UMR 8622, Orsay F-91405 (France); Donostia International Physics Center, Aptdo. 1072, 20080 San Sebastian (Spain); Lustrac, André de [Univ. Paris-Sud, Institut d’Electronique Fondamentale, UMR 8622, Orsay F-91405 (France); Univ. Paris-Ouest, 92410 Ville d’Avray (France)

    2015-12-15

    We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.

  11. Antenna Radiation Pattern Influence on the Localization Accuracy in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    COCA, E.

    2013-05-01

    Full Text Available Localization or position determination is one of the most common applications for the wireless sensor networks. Many investigations have been made during the last decade, most of the effort being concentrated in the direction of improving the accuracy of the positioning results by using complex filtering and correction algorithms, and other techniques such as radio maps or directive antennas for the reference nodes. The most common sources of errors include reflections on nearby objects, radio frequency noise, and variable characteristics of the communication channel. In the vast majority of cases, several assumptions have been made in order to simplify the computing algorithms or the complexity of nodes, and finally their cost. The omnidirectional radiation pattern of the node antennas is such an assumption. In this paper we investigate theoretically and validate by measurements the influence of the radiation pattern on the localization accuracy of a wireless sensor node network. By taking into consideration the orientation of nodes, which could be provided by a local digital compass on each node, we demonstrate that the position accuracy could be improved with a minimum of resources. All measurements were made in radio emissions controlled environment - a semi-anechoic chamber, without affecting the generality of the proposed solution.

  12. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    Science.gov (United States)

    Meena, M. L.; Parmar, Girish; Kumar, Mithilesh

    2016-03-01

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  13. Surface accuracy and radiation pattern characteristics of mesh deployable refector antennas

    Science.gov (United States)

    Ueno, Miyoshi; Ebisui, Takashi; Okamato, Teruki; Orikasa, Teruaki; Sugimoto, Toshio; Iso, Akio

    To facilitate the growth of mobile satellite communications, both an increase in the Equivalent Isotropically Radiated Power (EIRP) of satellites and improved frequency reuse are required to achiveve compact size, low cost terminal usage, and high channel capacity. High gain and low sidelobe antenna technology are very important for high EIRP and frequency reuse, respectively. These requirements are expected to be met by using a large deployable mesh reflector antenna, which is the key technology for future multibeam moble communications systems. In this paper, surface accruracy and related electrical characteristics are studied using a TETRUS-(Tetra Trigonal Prism Truss) type deployable mesh reflector antenna. Surface accuracy and related electrical characteristics of reflector antennas becaue any distortion of the ideal paraboloidal configuration causes antenna patterns to deteriorate, thereby reducing reflector aperture efficiency and increasing sidelobe and grating lobe levels. The sidelobe and grating lobe characteristics are especially important in frequency reuse. First, we show the problem with the radiation pattern characteristics of TETUS antenna. We then propose a new antenna configuration called the 'HYBRID TETRUS' that improves these characteristics. The mechanical performances of two partial deployable models are also described. Mechanical testing results reveal agreement between the calculated and measured values and high rigidities.

  14. Design and investigation of planar technology based ultra-wideband antenna with directional radiation patterns

    Energy Technology Data Exchange (ETDEWEB)

    Meena, M. L., E-mail: madan.meena.ece@gamil.com; Parmar, Girish, E-mail: girish-parmar2002@yahoo.com; Kumar, Mithilesh, E-mail: mith-kr@yahoo.com [Department of Electronics Engineering, Rajasthan Technical University, Kota (India)

    2016-03-09

    A novel design technique based on planar technology for ultra-wideband (UWB) antennas with different ground shape having directional radiation pattern is being presented here. Firstly, the L-shape corner reflector ground plane antenna is designed with microstrip feed line in order to achieve large bandwidth and directivity. Thereafter, for the further improvement in the directivity as well as for better impedance matching the parabolic-shape ground plane has been introduced. The coaxial feed line is given for the proposed directional antenna in order to achieve better impedance matching with 50 ohm transmission line. The simulation analysis of the antenna is done on CST Microwave Studio software using FR-4 substrate having thickness of 1.6 mm and dielectric constant of 4.4. The simulated result shows a good return loss (S11) with respect to -10 dB. The radiation pattern characteristic, angular width, directivity and bandwidth performance of the antenna have also been compared at different resonant frequencies. The designed antennas exhibit low cost, low reflection coefficient and better directivity in the UWB frequency band.

  15. Inhibition of bradycardia pacing caused by far-field atrial sensing in a third-generation cardioverter defibrillator with an automatic gain feature.

    Science.gov (United States)

    Curwin, J H; Roelke, M; Ruskin, J N

    1996-01-01

    The diagnostic accuracy of implantable cardioverter defibrillators may be improved by automatically adjusting gain algorithms, which in general reduce the likelihood of oversensing while maintaining the ability to detect the low amplitude signals associated with ventricular fibrillation. We present a patient with a third-generation device who developed prolonged ventricular asystole arising as a complication of the automatic gain feature. During asystole the device automatically increased sensitivity in order to prevent undersensing of ventricular fibrillation, which in this case resulted in far-field sensing of atrial activity and inhibition of ventricular pacing.

  16. Six years after the El Mayor-Cucapah earthquake: Transient far-field postseismic vertical motion observed by tide gauges and GPS

    Science.gov (United States)

    Smith-Konter, B. R.; Gonzalez-Ortega, J. A.; Merrifield, M. A.; Tong, X.; Sandwell, D. T.; Hardy, S.; Howell, S. M.

    2016-12-01

    On April 4, 2010, the El Mayor-Cucapah earthquake (Mw 7.2) ruptured a 120 km long set of faults of the southernmost San Andreas Fault System in northeastern Baja California, Mexico. Near-field coseismic GPS observations revealed up to 1.1 m of horizontal surface slip and 0.6 m of vertical subsidence at near-field stations. Early near-field InSAR and GPS time series postseismic observations also suggested several tens of centimeters of afterslip occurred within the first two years, however postseismic transients due to viscoelastic or poroelastic relaxation have also been offered as candidate models. Here we investigate the role of viscoelastic transients from six years of regional far-field ( 200 km from rupture) tide gauge and vertical GPS time series observations to further constrain postseismic deformation mechanisms. Vertical viscoelastic postseismic models of the El Mayor-Cucapah earthquake suggest alternating quadrants of uplift and subsidence straddling the rupture, with uplift to the north near the Salton Trough and subsidence to the west spanning the San Diego and Ensenada regions. These decaying transient motions are confirmed by both vertical postseismic GPS and tide gauge-altimetry observations, in both the near- and far fields. For example, tide gauge data in San Diego, which typically record vertical land motions on the order of a few millimeters per year, recorded nearly 30 mm of transient land subsidence over the first 3 years. We find that the magnitude and decay of far-field postseismic subsidence can be attributed to viscoelastic relaxation of the mantle assuming a temporally varying rheology; viscosities as low as 1017 Pa-s for at least the first 6-12 months, followed by an increasing viscosity on the order of 1018 Pa-s in the years following, best fit the data. While transient viscosity anomalies have been previously suggested from GPS data spanning the first 1.5 years following the earthquake [Pollitz et al., 2012], the combined results from

  17. Patterns of Care Among Patients Receiving Radiation Therapy for Bone Metastases at a Large Academic Institution

    Energy Technology Data Exchange (ETDEWEB)

    Ellsworth, Susannah G. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Alcorn, Sara R., E-mail: salcorn2@jhmi.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hales, Russell K.; McNutt, Todd R.; DeWeese, Theodore L. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Smith, Thomas J. [Department of Medical Oncology and Harry J. Duffey Family Program in Palliative Care, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)

    2014-08-01

    Purpose: This study evaluates outcomes and patterns of care among patients receiving radiation therapy (RT) for bone metastases at a high-volume academic institution. Methods and Materials: Records of all patients whose final RT course was for bone metastases from April 2007 to July 2012 were identified from electronic medical records. Chart review yielded demographic and clinical data. Rates of complicated versus uncomplicated bone metastases were not analyzed. Results: We identified 339 patients whose final RT course was for bone metastases. Of these, 52.2% were male; median age was 65 years old. The most common primary was non-small-cell lung cancer (29%). Most patients (83%) were prescribed ≤10 fractions; 8% received single-fraction RT. Most patients (52%) had a documented goals of care (GOC) discussion with their radiation oncologist; hospice referral rates were higher when patients had such discussions (66% with vs 50% without GOC discussion, P=.004). Median life expectancy after RT was 96 days. Median survival after RT was shorter based on inpatient as opposed to outpatient status at the time of consultation (35 vs 136 days, respectively, P<.001). Hospice referrals occurred for 56% of patients, with a median interval between completion of RT and hospice referral of 29 days and a median hospice stay of 22 days. Conclusions: These data document excellent adherence to American Society for Radiation Oncolology Choosing Wisely recommendation to avoid routinely using >10 fractions of palliative RT for bone metastasis. Nonetheless, single-fraction RT remains relatively uncommon. Participating in GOC discussions with a radiation oncologist is associated with higher rates of hospice referral. Inpatient status at consultation is associated with short survival.

  18. Far field photoluminescence imaging of single AlGaN nanowire in the sub-wavelength scale using confinement of polarized light

    Energy Technology Data Exchange (ETDEWEB)

    Sivadasan, A.K.; Dhara, Sandip [Nanomaterials and Sensors Section, Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam (India); Sardar, Manas [Theoretical Studies Section, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2017-03-15

    Till now the nanoscale focusing and imaging in the sub-diffraction limit is achieved mainly with the help of plasmonic field enhancement by confining the light assisted with noble metal nanostructures. Using far field imaging technique, we have recorded polarized spectroscopic photoluminescence (PL) imaging of a single AlGaN nanowire (NW) of diameter ∝100 nm using confinement of polarized light. It is found that the PL from a single NW is influenced by the proximity to other NWs. The PL intensity is proportional to 1/(l x d), where l and d are the average NW length and separation between the NWs, respectively. We suggest that the proximity induced PL intensity enhancement can be understood by assuming the existence of reasonably long lived photons in the intervening space between the NWs. A nonzero non-equilibrium population of such photons may cause stimulated emission leading to the enhancement of PL emission with the intensity proportional to 1/(l x d). The enhancement of PL emission facilitates far field spectroscopic imaging of a single semiconductor AlGaN NW of sub-wavelength dimension. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Breakdown of doublet recirculation and direct line drives by far-field flow in reservoirs: implications for geothermal and hydrocarbon well placement

    Science.gov (United States)

    Weijermars, R.; van Harmelen, A.

    2016-07-01

    An important real world application of doublet flow occurs in well design of both geothermal and hydrocarbon reservoirs. A guiding principle for fluid management of injection and extraction wells is that mass balance is commonly assumed between the injected and produced fluid. Because the doublets are considered closed loops, the injection fluid is assumed to eventually reach the producer well and all the produced fluid ideally comes from stream tubes connected to the injector of the well pair making up the doublet. We show that when an aquifer background flow occurs, doublets will rarely retain closed loops of fluid recirculation. When the far-field flow rate increases relative to the doublet's strength, the area occupied by the doublet will diminish and eventually vanishes. Alternatively, rather than using a single injector (source) and single producer (sink), a linear array of multiple injectors separated by some distance from a parallel array of producers can be used in geothermal energy projects as well as in waterflooding of hydrocarbon reservoirs. Fluid flow in such an arrangement of parallel source-sink arrays is shown to be macroscopically equivalent to that of a line doublet. Again, any far-field flow that is strong enough will breach through the line doublet, which then splits into two vortices. Apart from fundamental insight into elementary flow dynamics, our new results provide practical clues that may contribute to improve the planning and design of doublets and direct line drives commonly used for flow management of groundwater, geothermal and hydrocarbon reservoirs.

  20. Use of an atrial lead with very short tip-to-ring spacing avoids oversensing of far-field R-wave.

    Directory of Open Access Journals (Sweden)

    Christof Kolb

    Full Text Available OBJECTIVE: The AVOID-FFS (Avoidance of Far-Field R-wave Sensing study aimed to investigate whether an atrial lead with a very short tip-to-ring spacing without optimization of pacemaker settings shows equally low incidence of far-field R-wave sensing (FFS when compared to a conventional atrial lead in combination with optimization of the programming. METHODS: Patients receiving a dual chamber pacemaker were randomly assigned to receive an atrial lead with a tip-to-ring spacing of 1.1 mm or a lead with a conventional tip-to-ring spacing of 10 mm. Postventricular atrial blanking (PVAB was programmed to the shortest possible value of 60 ms in the study group, and to an individually determined optimized value in the control group. Atrial sensing threshold was programmed to 0.3 mV in both groups. False positive mode switch caused by FFS was evaluated at one and three months post implantation. RESULTS: A total of 204 patients (121 male; age 73±10 years were included in the study. False positive mode switch caused by FFS was detected in one (1% patient of the study group and two (2% patients of the control group (p = 0.62. CONCLUSION: The use of an atrial electrode with a very short tip-to-ring spacing avoids inappropriate mode switch caused by FFS without the need for individual PVAB optimization. TRIAL REGISTRATION: ClinicalTrials.gov NCT00512915.

  1. Pareto optimality between width of central lobe and peak sidelobe intensity in the far-field pattern of lossless phase-only filters for enhancement of transverse resolution.

    Science.gov (United States)

    Mukhopadhyay, Somparna; Hazra, Lakshminarayan

    2015-11-01

    Resolution capability of an optical imaging system can be enhanced by reducing the width of the central lobe of the point spread function. Attempts to achieve the same by pupil plane filtering give rise to a concomitant increase in sidelobe intensity. The mutual exclusivity between these two objectives may be considered as a multiobjective optimization problem that does not have a unique solution; rather, a class of trade-off solutions called Pareto optimal solutions may be generated. Pareto fronts in the synthesis of lossless phase-only pupil plane filters to achieve superresolution with prespecified lower limits for the Strehl ratio are explored by using the particle swarm optimization technique.

  2. Polarized Uniform Linear Array System: Beam Radiation Pattern, Beamforming Diversity Order, and Channel Capacity

    Directory of Open Access Journals (Sweden)

    Xin Su

    2015-01-01

    Full Text Available There have been many studies regarding antenna polarization; however, there have been few publications on the analysis of the channel capacity for polarized antenna systems using the beamforming technique. According to Chung et al., the channel capacity is determined by the density of scatterers and the transmission power, which is obtained based on the assumption that scatterers are uniformly distributed on a 3D spherical scattering model. However, it contradicts the practical scenario, where scatterers may not be uniformly distributed under outdoor environment, and lacks the consideration of fading channel gain. In this study, we derive the channel capacity of polarized uniform linear array (PULA systems using the beamforming technique in a practical scattering environment. The results show that, for PULA systems, the channel capacity, which is boosted by beamforming diversity, can be determined using the channel gain, beam radiation pattern, and beamforming diversity order (BDO, where the BDO is dependent on the antenna characteristics and array configurations.

  3. Inferring ultraviolet anatomical exposure patterns while distinguishing the relative contribution of radiation components

    Energy Technology Data Exchange (ETDEWEB)

    Vuilleumier, Laurent [Federal Office of Meteorology and Climatology, MeteoSwiss, Payerne (Switzerland); Milon, Antoine; Vernez, David [Institute of Work and Health, University of Lausanne and Geneva, Lausanne (Switzerland); Bulliard, Jean-Luc [Cancer Epidemiology Unit, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne (Switzerland); Moccozet, Laurent [Institute of Services Science, University of Geneva (Switzerland)

    2013-05-10

    Exposure to solar ultraviolet (UV) radiation is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors, but individual exposure data remain scarce. While ground UV irradiance is monitored via different techniques, it is difficult to translate such observations into human UV exposure or dose because of confounding factors. A multi-disciplinary collaboration developed a model predicting the dose and distribution of UV exposure on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a simulation tool that estimates solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by various body locations is computed for direct, diffuse and reflected radiation separately. Dosimetric measurements obtained in field conditions were used to assess the model performance. The model predicted exposure to solar UV adequately with a symmetric mean absolute percentage error of 13% and half of the predictions within 17% range of the measurements. Using this tool, solar UV exposure patterns were investigated with respect to the relative contribution of the direct, diffuse and reflected radiation. Exposure doses for various body parts and exposure scenarios of a standing individual were assessed using erythemally-weighted UV ground irradiance data measured in 2009 at Payerne, Switzerland as input. For most anatomical sites, mean daily doses were high (typically 6.2-14.6 Standard Erythemal Dose, SED) and exceeded recommended exposure values. Direct exposure was important during specific periods (e.g. midday during summer), but contributed moderately to the annual dose, ranging from 15 to 24% for vertical and horizontal body parts, respectively. Diffuse irradiation explained about 80% of the cumulative annual exposure dose.

  4. Algorithm for the synthesis of linear antenna arrays with desired radiation pattern and integral amplitude coefficients

    Directory of Open Access Journals (Sweden)

    Sadchenko A. V.

    2015-06-01

    Full Text Available Ahe problem of technical implementation of phased array antennas (PAR with the required radiation pattern (RP is the complexity of the construction of the beamforming device that consists of a set of controlled attenuators and phase shifters. It is possible to simplify the technical implementation of PAR, if complex representation of coefficients of amplitude-phase distribution of the field along the lattice is approximated by real values in the synthesis stage. It is known that the amplitude distribution of the field in the aperture of the antenna array and the radiation pattern are associated with Fourier transform. Thus, the amplitude and phase coefficients are first calculated using the Fourier transform, and then processed according to the selected type of circuit realization of attenuators and phase shifters. The calculation of the inverse Fourier transform of the modified coefficients allows calculating the synthesized orientation function. This study aims to develop a search algorithm for amplitude and phase coefficients, taking into account the fact that integer-valued amplitudes and phases are technically easier to implement than real ones. Synthesis algorithm for equidistant linear array with a half-wavelength irradiators pitch (&l;/2 is as follows. From a given directivity function the discrete Fourier transform (DFT in the form of an array of complex numbers is found, the resulting array is then transformed into a set of attenuations for attenuators and phase shifts for phase shifters, while the amplitude coefficients are rounded off to integers, and phases are binarizated (0, ?. The practical value of this algorithm is particularly high when using controlled phase shifters and attenuators integrally. The work confirms the possibility of a thermoelectric converter of human body application for an electronic medical thermometer power supply.

  5. Simulation of 3-D radiation beam patterns propagated through a planar interface from ultrasonic phased array transducers.

    Science.gov (United States)

    Song, Sung-Jin; Kim, Chang-Hwan

    2002-05-01

    Phased array transducers are quite often mounted on solid wedges with specific angles in many practical ultrasonic inspections of thin plates phased array techniques with testing set-up, it is essential to have thorough understanding on the characteristics of radiation beam pattern produced in the interrogated medium. To address such a need, this paper proposes a systematic way to calculate full 3-D radiation beam patterns produced in the interrogated solid medium by phased array transducers mounted on a solid wedge. In order to investigate the characteristics of radiation beam patterns in steel, simulation is carried out for 7.5 MHz array transducers mounted on an acrylic wedge with the angle of 15.45 degrees with various of steering angles and/or focal planes.

  6. Magnitude and pattern of Arctic warming governed by the seasonality of radiative forcing

    Science.gov (United States)

    Bintanja, Richard; Krikken, Folmer

    2015-04-01

    Observed and projected climate warming is strongest in the Arctic regions, and maximum in autumn/winter. Attempts to explain this feature have focused primarily on identifying the associated climate feedbacks, particularly the ice-albedo and lapse-rate feedbacks. However, the impact of seasonally varying climate forcing has not been identified and quantified. Here we use a state-of-the-art global climate model in idealized seasonal forcing simulations to show that Arctic warming is very sensitive to the season in which the radiative forcing occurs. More specifically, Arctic warming and sea ice decline (especially in winter) are particularly sensitive to forcing in spring, during which the energy is effectively 'absorbed' by the ocean (through sea ice melt and ocean warming, amplified by the ice-albedo feedback) and consequently released to the lower atmosphere in autumn and winter, mainly along the sea ice periphery. In contrast, wintertime radiative forcing yields a more evenly distributed winter warming, which, surprisingly, in certain regions is even smaller than that due to spring forcing. The dependence of the magnitude and pattern of Arctic warming on the seasonality of the climate forcing has important implications in terms of projected increases in anthropogenic forcing. For instance, shipping-induced emissions such as those of black carbon are projected to peak in the ice-free summer and will thereby exert a comparatively strong impact on Arctic warming.

  7. Radiation Pattern Measurement of a Low-Profile Wearable Antenna Using an Optical Fibre and a Solid Anthropomorphic Phantom

    Directory of Open Access Journals (Sweden)

    Tian Hong Loh

    2014-08-01

    Full Text Available This paper presents a study into radiation pattern measurements of an electrically small dielectric resonator antenna (DRA operating between 2.4 and 2.5 GHz in the industrial, scientific and medical (ISM radio band for body-centric wireless communication applications. To eliminate the distortion of the radiation pattern associated with the unwanted radiation from a metallic coaxial cable feeding the antenna we have replaced it with a fibre optic feed and an electro-optical (EO transducer. The optical signal is then converted back to RF using an Opto-Electric Field Sensor (OEFS system. To ensure traceable measurements of the radiation pattern performance of the wearable antenna a generic head and torso solid anthropomorphic phantom model has been employed. Furthermore, to illustrate the benefits of the method, numerical simulations of the co-polar and cross-polar H-plane radiation patterns at 2.4, 2.45, and 2.5 GHz are compared with the measured results obtained using: (i an optical fibre; and (ii a metallic coaxial cable.

  8. Branching patterns of intramural coronary vessels determined by microangiography using synchrotron radiation.

    Science.gov (United States)

    Tanaka, A; Mori, H; Tanaka, E; Mohammed, M U; Tanaka, Y; Sekka, T; Ito, K; Shinozaki, Y; Hyodo, K; Ando, M; Umetani, K; Tanioka, K; Kubota, M; Abe, S; Handa, S; Nakazawa, H

    1999-06-01

    The intramural coronary artery (IMCA) with a diameter of 50-500 micrometers is critical for blood supply to the inner layers of heart muscle. We introduced digital measurement to microangiography using monochromatic synchrotron radiation and quantified branching patterns of the IMCA, the epicardial coronary artery (EPCA), and the distal ileal artery (DIA). The pre- and postbranching diameters were measured (95-1,275 micrometers) in seven dogs. A typical arterial segment divided into two nearly equivalent branches, and a regression line of daughter-to-mother diameter plots was almost identical among the EPCA (y = 0.838x - 16.7 in micrometers), IMCA (y = 0.737x - 2.18), and DIA (y = 0.755x + 8.63). However, a considerable difference was present at a segment where a proximal IMCA branched off from an EPCA (y = 0.182x + 90.2). Moreover, a proximal IMCA diameter had no relationship to the branching order from an EPCA. The precision of this method was confirmed by the good correlation of diameter measurements between two independent observers (r = 0.999, y = 1.02x - 1.07). In conclusion, using digital microangiography we demonstrated that the self-similar branching pattern of coronary arteries was discrete at the connection between the IMCA and EPCA.

  9. Humic substances in performance assessment of nuclear waste disposal: Actinide and iodine migration in the far-field. Second technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Buckau, G. (ed.)

    2004-07-01

    The present report describes progress within the second year of the EC-project ''Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field''. Without being a formal requirement of the commission or co-funding bodies, this report documents results in great technical detail. It is an open report and thus makes the detailed results available to a broad scientific community. The report contains an executive summary written by the coordinator. More detailed results are given as individual contributions in the form of 23 annexes. Not all results are discussed or referred to in the executive summary report and thus readers with a deeper interest also need to consult the annexes. (orig.)

  10. Assessment of the Bordas-Carnot Losses within the diffuser of tidal turbines using far-field and near-field CFD models.

    Science.gov (United States)

    Hajaali, Arthur

    2017-04-01

    This project has for ambition to analyse and further the general understanding on cross-flows interactions and behaviours at the mouth of a mini/small tidal hydropower plant and a river. Although, the study of these interactions could benefit and find applications in multiple hydraulic problems, this project concentrates its focus on the influence of the transposed turbulences generated by the cross-flow into the diffuser. These eddies affect the overall performance and efficiency of the bulb-turbines by minimizing the pressure recovery. In the past, these turbulences were accounted with the implementation of the Bordas-Carnot losses coefficient for the design of tidal project using bulb-turbines. The bulb turbine technology has been the interest and subject of many scientific papers but most of them concentrate and narrow their focus on the design of the rotor, blades and combiner. This project wants to focus the design of the diffuser by performing an analysis on the development of eddies and the turbulences using computational fluid dynamic (CFD) models. The Severn estuary is endowed with one of the highest tidal range around the hemisphere. The first part of the research requires to select case studies sites such as Briton-Ferry to virtually design mini-tidal plant in 0-Dimentional (D), 2D and 3D modelling to study development and behaviour of turbulences within the diffuser. The far-field model represents the marine environment prior and after the structure where bulb turbines are located. The near-field modelling has allowed researcher to study at much higher resolution and precision the design of a single turbine feeding model with predetermined and fix boundary condition. For this reason, a near-field model is required to study in depth the behaviour and evolution of the turbulence with the diffuser. One of the main challenge and advancement of this research is to find a methodology and system to link the far-field and near-field modelling to produce an

  11. Dynamic Interaction Behavior between Jumbo Container Crane and Pile-Supported Wharf under NearField and Far-Field Ground Motions

    Directory of Open Access Journals (Sweden)

    J. R. LI

    2016-02-01

    Full Text Available Playing an important role in local and national seaport activities, container wharves are susceptible to structural failure and damage during earthquake events. Therefore, factors that affect the seismic response of crane–wharf structures under different types of earthquake ground motions should be elucidated. In this paper, 3D finite element models were established to investigate the differences of natural vibration characteristics between the wharf and crane–wharf structures. The dynamic response of a typical pile-supported wharf structure and the interaction behavior of a crane and wharf structural system under seismic actions of near-field and far-field ground motions were studied by performing numerical simulation and time-history response analysis. Axial force–moment relation curves were adopted to analyze the elastic–plastic limit state of the wharf structure under different ground motions. Results showed that the consideration of the container crane increased the natural vibration period of the pile-supported wharf structure and affected the dynamic characteristics of the structure. Compared with the far-field earthquake ground motion, the nearfield earthquake exerted a more significant impact on the structural dynamic response that controlled the elastic–plastic limit state. With the presence of a crane, the moment and shear force of the pile-top decreased and the location of the extreme value moved down obviously. The findings demonstrated that considering the crane changed the failure mechanism of the wharf structure, and the eccentric effect of the crane may amplify the dynamic response as the peak ground acceleration increases. The results provide reference for the seismic design and the evaluation of the seismic response of container wharves.

  12. Forward Scatter Radar for Air Surveillance: Characterizing the Target-Receiver Transition from Far-Field to Near-Field Regions

    Directory of Open Access Journals (Sweden)

    Marta Tecla Falconi

    2017-01-01

    Full Text Available A generalized electromagnetic model is presented in order to predict the response of forward scatter radar (FSR systems for air-target surveillance applications in both far-field and near-field conditions. The relevant scattering problem is tackled by developing the Helmholtz–Kirchhoff formula and Babinet’s principle to express the scattered and the total fields in typical FSR configurations. To fix the distinctive features of this class of problems, our approach is applied here to metallic targets with canonical rectangular shapes illuminated by a plane wave, but the model can straightforwardly be used to account for more general scenarios. By exploiting suitable approximations, a simple analytical formulation is derived allowing us to efficiently describe the characteristics of the FSR response for a target transitioning with respect to the receiver from far-field to near-field regions. The effects of different target electrical sizes and detection distances on the received signal, as well as the impact of the trajectory of the moving object, are evaluated and discussed. All of the results are shown in terms of quantities normalized to the wavelength and can be generalized to different configurations once the carrier frequency of the FSR system is set. The range of validity of the proposed closed-form approach has been checked by means of numerical analyses, involving comparisons also with a customized implementation of a full-wave commercial CAD tool. The outcomes of this study can pave the way for significant extensions on the applicability of the FSR technique.

  13. Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns.

    Science.gov (United States)

    Jawla, Sudheer K; Nanni, Emilio A; Shapiro, Michael A; Woskov, Paul P; Temkin, Richard J

    2012-06-01

    This work focuses on the accuracy of the mode content measurements in an overmoded corrugated waveguide using measured radiated field patterns. Experimental results were obtained at 250 GHz using a vector network analyzer with over 70 dB of dynamic range. The intensity and phase profiles of the fields radiated from the end of the 19 mm diameter helically tapped brass waveguide were measured on planes at 7, 10, and 13 cm from the waveguide end. The measured fields were back propagated to the waveguide aperture to provide three independent estimates of the field at the waveguide exit aperture. Projecting that field onto the modes of the guide determined the waveguide mode content. The three independent mode content estimates were found to agree with one another to an accuracy of better than ±0.3%. These direct determinations of the mode content were compared with indirect measurements using the experimentally measured amplitude in three planes, with the phase determined by a phase retrieval algorithm. The phase retrieval technique using the planes at 7, 10, and 13 cm yielded a mode content estimate in excellent agreement, within 0.3%, of the direct measurements. Phase retrieval results using planes at 10, 20, and 30 cm were less accurate due to truncation of the measurement in the transverse plane. The reported measurements benefited greatly from a precise mechanical alignment of the scanner with respect to the waveguide axis. These results will help to understand the accuracy of mode content measurements made directly in cold test and indirectly in hot test using the phase retrieval technique.

  14. Emission and propagation of Saturn kilometric radiation: Magnetoionic modes, beaming pattern, and polarization state

    Science.gov (United States)

    Lamy, L.; Cecconi, B.; Zarka, P.; Canu, P.; Schippers, P.; Kurth, W. S.; Mutel, R. L.; Gurnett, D. A.; Menietti, D.; Louarn, P.

    2011-04-01

    The Cassini mission crossed the source region of the Saturn kilometric radiation (SKR) on 17 October 2008. On this occasion, the Radio and Plasma Wave Science (RPWS) experiment detected both local and distant radio sources, while plasma parameters were measured in situ by the magnetometer and the Cassini Plasma Spectrometer. A goniopolarimetric inversion was applied to RPWS three-antenna electric measurements to determine the wave vector k and the complete state of polarization of detected waves. We identify broadband extraordinary (X) mode as well as narrowband ordinary (O) mode SKR at low frequencies. Within the source region, SKR is emitted just above the X mode cutoff frequency in a hot plasma, with a typical electron-to-wave energy conversion efficiency of ˜1% (2% peak). The knowledge of the k vector is then used to derive the locus of SKR sources in the kronian magnetosphere, which shows X and O components emanating from the same regions. We also compute the associated beaming angle at the source θ‧ = (k, -B) either from (1) in situ measurements or a model of the magnetic field vector (for local to distant sources) or (2) polarization measurements (for local sources). Obtained results, similar for both modes, suggest quasi-perpendicular emission for local sources, whereas the beaming pattern of distant sources appears as a hollow cone with a frequency-dependent constant aperture angle: θ‧ = 75° ± 15° below 300 kHz, decreasing at higher frequencies to reach θ‧ (1000 kHz) = 50° ± 25°. Finally, we investigate quantitatively the SKR polarization state, observed to be strongly elliptical at the source, and quasi-purely circular for sources located beyond approximately two kronian radii. We show that conditions of weak mode coupling are achieved along the raypath, under which the magnetoionic theory satisfactorily describes the evolution of the observed polarization. These results are analyzed comparatively with the auroral kilometric radiation at

  15. Evaluation of breathing patterns for respiratory-gated radiation therapy using the respiration regularity index

    Science.gov (United States)

    Cheong, Kwang-Ho; Lee, MeYeon; Kang, Sei-Kwon; Yoon, Jai-Woong; Park, SoAh; Hwang, Taejin; Kim, Haeyoung; Kim, KyoungJu; Han, Tae Jin; Bae, Hoonsik

    2015-01-01

    suitable for respiratory-gated radiation therapy (RGRT). Fluctuations in the breathing cycle and the amplitude were especially determinative of ρ. If the respiration regularity of a patient's first session was known, it could be estimated through subsequent sessions. Notably, the breathing patterns of the lung cancer patients were more irregular than those of the liver cancer patients. Respiration regularity could be objectively determined by using a composite index, ρ. Such a single-index testing of respiration regularity can facilitate determination of RGRT availability in clinical settings, especially for free-breathing cases.

  16. Pattern scaling effect on the radiative properties of wafer’s surface

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper presents a parametric study of the radiative properties of patterned wafers with a polysilicon gate array on the Si substrate, considering the effect of wavelength and polarization. The finite-difference time-domain (FDTD) method was employed to examine the pattern scaling effect on the spectral absorptance via numerical solutions of the Maxwell’s equations. The effective medium theory (EMT) was also used to help explain the absorptance predictions. While the gate sizes are very small compared to wavelength, the results show rather unusual phenomena. The absorptance calculated by EMT is in agreement with FDTD in the cases with small gate and period sizes. With the increase of period and decrease of the ratio of the gate width to the grating period, both EMT and FDTD results for the TM (transverse magnetic) mode approach to pure silicon since the grating effect diminishes. However, the error of EMT results for the TE mode in some cases becomes considerable due to the limitation of EMT, which requires the period to be significantly smaller than the wavelength. Besides, the TE (transverse electric) absorptance curve separates from that of plain Si when the wavelength equals the grating period, this is because the gate can interact with its neighbering region by diffraction and the diffraction effects are weak, when the wavelength is small. The peak absorptance can be attributed to the thin film effect. It shows that a slight increase in the gate height can drastically increase the absorptance and the increased gate height shifts the peak absorptance to longer wavelength due to the increase of optical path length in the effective thin film. This work is of great importance for optimization of advanced annealing techniques in semiconductor manufacturing.

  17. Design, Analysis, and Verification of Ka-Band Pattern Reconfigurable Patch Antenna Using RF MEMS Switches

    Directory of Open Access Journals (Sweden)

    Zhongliang Deng

    2016-08-01

    Full Text Available This paper proposes a radiating pattern reconfigurable antenna by employing RF Micro-electromechanical Systems (RF MEMS switches. The antenna has a low profile and small size of 4 mm × 5 mm × 0.4 mm, and mainly consists of one main patch, two assistant patches, and two RF MEMS switches. By changing the RF MEMS switches operating modes, the proposed antenna can switch among three radiating patterns (with main lobe directions of approximately −17.0°, 0° and +17.0° at 35 GHz. The far-field vector addition model is applied to analyse the pattern. Comparing the measured results with analytical and simulated results, good agreements are obtained.

  18. The radiation of sound by the instability waves of a compressible plane turbulent shear layer

    Science.gov (United States)

    Tam, C. K. W.; Morris, P. J.

    1980-01-01

    The problem of acoustic radiation generated by instability waves of a compressible plane turbulent shear layer is solved. The solution provided is valid up to the acoustic far-field region. It represents a significant improvement over the solution obtained by classical hydrodynamic-stability theory which is essentially a local solution with the acoustic radiation suppressed. The basic instability-wave solution which is valid in the shear layer and the near-field region is constructed in terms of an asymptotic expansion using the method of multiple scales. This solution accounts for the effects of the slightly divergent mean flow. It is shown that the multiple-scales asymptotic expansion is not uniformly valid far from the shear layer. Continuation of this solution into the entire upper half-plane is described. The extended solution enables the near- and far-field pressure fluctuations associated with the instability wave to be determined. Numerical results show that the directivity pattern of acoustic radiation into the stationary medium peaks at 20 degrees to the axis of the shear layer in the downstream direction for supersonic flows. This agrees qualitatively with the observed noise-directivity patterns of supersonic jets.

  19. Far-Field Tsunami Impact in the North Atlantic Basin from Large Scale Flank Collapses of the Cumbre Vieja Volcano, La Palma

    Science.gov (United States)

    Tehranirad, Babak; Harris, Jeffrey C.; Grilli, Annette R.; Grilli, Stephan T.; Abadie, Stéphane; Kirby, James T.; Shi, Fengyan

    2015-12-01

    In their pioneering work, Ward and Day suggested that a large scale flank collapse of the Cumbre Vieja Volcano (CVV) on La Palma (Canary Islands) could trigger a mega-tsunami throughout the North Atlantic Ocean basin, causing major coastal impact in the far-field. While more recent studies indicate that near-field waves from such a collapse would be more moderate than originally predicted by Ward and Day [Løvholt et al. (J Geophy Res 113:C09026, 2008); Abadie et al. (J Geophy Res 117:C05030, 2012)], these would still be formidable and devastate the Canary Island, while causing major impact in the far-field at many locations along the western European, African, and the US east coasts. Abadie et al. (J Geophy Res 117:C05030, 2012) simulated tsunami generation and near-field tsunami impact from a few CVV subaerial slide scenarios, with volumes ranging from 20 to 450 km^3; the latter representing the most extreme scenario proposed by Ward and Day. They modeled tsunami generation, i.e., the tsunami source, using THETIS, a 3D Navier-Stokes (NS) multi-fluid VOF model, in which slide material was considered as a nearly inviscid heavy fluid. Near-field tsunami impact was then simulated for each source using FUNWAVE-TVD, a dispersive and fully nonlinear long wave Boussinesq model [ Shi et al. (Ocean Modell 43-44:36-51, 2012); Kirby et al. (Ocean Modeling, 62:39-55, 2013)]. Here, using FUNWAVE-TVD for a series of nested grids of increasingly fine resolution, we model and analyze far-field tsunami impact from two of Abadie et al.'s extreme CVV flank collapse scenarios: (i) that deemed the most "credible worst case scenario" based on a slope stability analysis, with a 80 km^3 volume; and (ii) the most extreme scenario, similar to Ward and Day's, with a 450 km^3 volume. Simulations are performed using a one-way coupling scheme in between two given levels of nested grids. Based on the simulation results, the overall tsunami impact is first assessed in terms of maximum surface

  20. Humic substances in performance assessment of nuclear waste disposal: Actinide and iodine migration in the far-field. Third technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Buckau, G.

    2005-04-01

    The present report describes progress within the third and final year of the EC-project 'Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field'. The work conducted within the present project builds on a number of previous activities/project supported by the Commission. It finds its continuation within different EC FP 6 instruments and also provides for additional continued cooperation through network structures resulting from the broad cooperation within the project. Without being a formal requirement of the Commission or co-funding bodies, this report documents results in great technical detail and makes the results available to a broad scientific community. The report contains an executive summary written by the coordinator. More detailed results are given as individual contributions in the form of 12 annexes. Not all results are discussed or referred to in the executive summary report and thus readers with a deeper interest also need to consult the annexes. The overall objectives were to generate knowledge about the impact of humic substances on the migration of actinides and iodine in the far-field of a nuclear waste repository. In the beginning, focus was rather on the potential enhancement due to humic colloid mediated radionuclide transport. Thereby, sources, inventory, stability and mobility of dissolved humic substances in their colloidal form formed a key topic. Other key topics were the interaction with actinides and iodine, transport studies under near-natural conditions in the laboratory, rationalization of knowledge in models and application to three migration cases for visualization of the overall outcome. Changes relative to the original objectives were given by moving emphasis of natural chemical analogue studies from the question of kinetic exchange constants for different inventories in natural and laboratory systems to the study of anthropogenic actinide contaminants in the

  1. Effects of near surface soil moisture profiles during evaporation on far-field ground-penetrating radar data: A numerical study

    KAUST Repository

    Moghadas, Davood

    2013-01-01

    We theoretically investigated the effect of vapor flow on the drying front that develops in soils when water evaporates from the soil surface and on GPR data. The results suggest the integration of the full-wave GPR model with a coupled water, vapor, and heat flow model to accurately estimate the soil hydraulic properties. We investigated the Effects of a drying front that emerges below an evaporating soil surface on the far-field ground-penetrating radar (GPR) data. First, we performed an analysis of the width of the drying front in soils with 12 different textures by using an analytical model. Then, we numerically simulated vertical soil moisture profiles that develop during evaporation for the soil textures. We performed the simulations using a Richards flow model that considers only liquid water flow and a model that considers coupled water, vapor, and heat flows. The GPR signals were then generated from the simulated soil water content profiles taking into account the frequency dependency of apparent electrical conductivity and dielectric permittivity. The analytical approach indicated that the width of the drying front at the end of Stage I of the evaporation was larger in silty soils than in other soil textures and smaller in sandy soils. We also demonstrated that the analytical estimate of the width of the drying front can be considered as a proxy for the impact that a drying front could have on far-field GPR data. The numerical simulations led to the conclusion that vapor transport in soil resulted in S-shaped soil moisture profiles, which clearly influenced the GPR data. As a result, vapor flow needs to be considered when GPR data are interpreted in a coupled inversion approach. Moreover, the impact of vapor flow on the GPR data was larger for silty than for sandy soils. These Effects on the GPR data provide promising perspectives regarding the use of radars for evaporation monitoring. © Soil Science Society of America 5585 Guilford Rd., Madison, WI

  2. THE EARTHQUAKE AND TSUNAMI OF 27 FEBRUARY 2010 IN CHILE – Evaluation of Source Mechanism and of Near and Far-field Tsunami Effects

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2010-01-01

    Full Text Available The great earthquake of February 27, 2010 occurred as thrust-faulting along a highly stressed coastal segment of Chile's central seismic zone - extending from about 33oS to 37oS latitude - where active, oblique subduction of the Nazca tectonic plate below South America occurs at the high rate of up to 80 mm per year. It was the 5th most powerful earthquake in recorded history and the largest in the region since the extremely destructive May 22, 1960 magnitude Mw9.5 earthquake near Valdivia. The central segment south of Valparaiso from about 34o South to 36o South had been identified as a moderate seismic gap where no major or great, shallow earthquakes had occurred in the last 120 years, with the exception of a deeper focus, inland event in 1939. The tsunami that was generated by the 2010 earthquake was highest at Robinson Crusoe Island in the Juan Fernández archipelago as well as in Talchuano, Dichato, Pelluhue and elsewhere on the Chilean mainland, causing numerous deaths and destruction. Given the 2010 earthquake’s great moment magnitude of 8.8, shallow focal depth and coastal location, it would have been expected that the resulting tsunami would have had much greater Pacific-wide, far field effects similar to those of 1960, which originated from the same active seismotectonic zone. However, comparison of the characteristics of the two events indicates substantial differences in source mechanisms, energy release, ruptures, spatial clustering and distributions of aftershocks, as well as in geometry of subduction and extent of crustal displacements on land and in the ocean. Also, the San Bautista and the Juan Fernández Islands - ridges rising from the ocean floor – as well as the O’Higgins seamount/guyot may have trapped some of the tsunami energy, thus accounting for the smaller, far field tsunami effects observed elsewhere in the Pacific. Apparently, complex, localized structural anomalies and interactions of the Nazca tectonic plate

  3. Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study

    Directory of Open Access Journals (Sweden)

    Rafati A.

    2015-09-01

    Full Text Available Introduction: The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz. Materials and Methods: Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF radiation emitted from a common Jammer at a distance of 1m from the jammer’s antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T, the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz as stimuli. Results: The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

  4. Stage III Melanoma in the Axilla: Patterns of Regional Recurrence After Surgery With and Without Adjuvant Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Pinkham, Mark B., E-mail: mark.pinkham@health.qld.gov.au [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); University of Queensland, Brisbane (Australia); Foote, Matthew C. [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); Queensland Melanoma Project, Princess Alexandra Hospital, Brisbane (Australia); Diamantina Institute, Brisbane (Australia); University of Queensland, Brisbane (Australia); Burmeister, Elizabeth [Nursing Practice Development Unit, Princess Alexandra Hospital, Brisbane (Australia); Research Centre for Clinical and Community Practice, Griffith University, Brisbane (Australia); Thomas, Janine [Queensland Melanoma Project, Princess Alexandra Hospital, Brisbane (Australia); Meakin, Janelle [Clinical Trials Research Unit, Princess Alexandra Hospital, Brisbane (Australia); Smithers, B. Mark [Queensland Melanoma Project, Princess Alexandra Hospital, Brisbane (Australia); University of Queensland, Brisbane (Australia); Burmeister, Bryan H. [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); Queensland Melanoma Project, Princess Alexandra Hospital, Brisbane (Australia); University of Queensland, Brisbane (Australia)

    2013-07-15

    Purpose: To describe the anatomic distribution of regionally recurrent disease in patients with stage III melanoma in the axilla after curative-intent surgery with and without adjuvant radiation therapy. Methods and Materials: A single-institution, retrospective analysis of a prospective database of 277 patients undergoing curative-intent treatment for stage III melanoma in the axilla between 1992 and 2012 was completed. For patients who received radiation therapy and those who did not, patterns of regional recurrence were analyzed, and univariate analyses were performed to assess for potential factors associated with location of recurrence. Results: There were 121 patients who received adjuvant radiation therapy because their clinicopathologic features conferred a greater risk of regional recurrence. There were 156 patients who received no radiation therapy. The overall axillary control rate was 87%. There were 37 patients with regional recurrence; 17 patients had received adjuvant radiation therapy (14%), and 20 patients (13%) had not. The likelihood of in-field nodal recurrence was significantly less in the adjuvant radiation therapy group (P=.01) and significantly greater in sites adjacent to the axilla (P=.02). Patients with high-risk clinicopathologic features who did not receive adjuvant radiation therapy also tended to experience in-field failure rather than adjacent-field failure. Conclusions: Patients who received adjuvant radiation therapy were more likely to experience recurrence in the adjacent-field regions rather than in the in-field regions. This may not simply reflect higher-risk pathology. Using this data, it may be possible to improve outcomes by reducing the number of adjacent-field recurrences after adjuvant radiation therapy.

  5. Enhancing radiative energy transfer through thermal extraction

    Science.gov (United States)

    Tan, Yixuan; Liu, Baoan; Shen, Sheng; Yu, Zongfu

    2016-06-01

    Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a). In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics. Thermal extraction works by using a specially designed thermal extractor to convert and guide the near-field energy to the far field, as shown in Fig. 1b. The same blackbody as shown in Fig. 1a is placed closely below the thermal extractor with a spacing smaller than the thermal wavelength. The near-field coupling transfers radiative energy with a density greater than σT4. The thermal extractor, made from transparent and high-index or structured materials, does not emit or absorb any radiation. It transforms the near-field energy and sends it toward the far field. As a result, the total amount of far-field radiative heat dissipated by the same blackbody is greatly enhanced above SσT4, where S is the area of the emitter. This paper will review the progress in thermal

  6. High resolution surface solar radiation patterns over Eastern Mediterranean: Satellite, ground-based, reanalysis data and radiative transfer simulations

    Science.gov (United States)

    Alexandri, G.; Georgoulias, A.; Meleti, C.; Balis, D.

    2013-12-01

    Surface solar radiation (SSR) and its long and short term variations play a critical role in the modification of climate and by extent of the social and financial life of humans. Thus, SSR measurements are of primary importance. SSR is measured for decades from ground-based stations for specific spots around the planet. During the last decades, satellite observations allowed for the assessment of the spatial variability of SSR at a global as well as regional scale. In this study, a detailed spatiotemporal view of the SSR over Eastern Mediterranean is presented at a high spatial resolution. Eastern Mediterranean is affected by various aerosol types (continental, sea, dust and biomass burning particles) and encloses countries with significant socioeconomical changes during the last decades. For the aims of this study, SSR data from satellites (Climate Monitoring Satellite Application Facility - CM SAF) and our ground station in Thessaloniki, a coastal city of ~1 million inhabitants in northern Greece, situated in the heart of Eastern Mediterranean (Eppley Precision pyranometer and Kipp & Zonen CM-11 pyranometer) are used in conjunction with radiative transfer simulations (Santa Barbara DISORT Atmospheric Radiative Transfer - SBDART). The CM SAF dataset used here includes monthly mean SSR observations at a high spatial resolution of 0.03x0.03 degrees for the period 1983-2005. Our ground-based SSR observations span from 1983 until today. SBDART radiative transfer simulations were implemented for a number of spots in the area of study in order to calculate the SSR. High resolution (level-2) aerosol and cloud data from MODIS TERRA and AQUA satellite sensors were used as input, as well as ground-based data from the AERONET. Data from other satellites (Earth Probe TOMS, OMI, etc) and reanalysis projects (ECMWF) were used where needed. The satellite observations, the ground-based measurements and the model estimates are validated against each other. The good agreement

  7. Enhancing radiative energy transfer through thermal extraction

    Directory of Open Access Journals (Sweden)

    Tan Yixuan

    2016-06-01

    Full Text Available Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a. In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics.

  8. Far-Field Tunable Nano-focusing Based on Metallic Slits Surrounded with Nonlinear-Variant Widths and Linear-Variant Depths of Circular Dielectric Grating

    CERN Document Server

    Cao, Peng-Fei; Zhang, Xiao-Ping; Lu, Wei-Ping; Kong, Wei-Jie; Liang, Xue-Wu

    2013-01-01

    In this work, we design a new tunable nanofocusing lens by the linear-variant depths and nonlinear-variant widths of circular grating for far field practical applications. The constructively interference of cylindrical surface plasmon launched by the subwavelength metallic structure can form a subdiffraction-limited focus, and the focal length of the this structures can be adjusted if the each groove depth and width of circular grating are arranged in traced profile. According to the numerical calculation, the range of focusing points shift is much more than other plasmonic lens, and the relative phase of emitting light scattered by surface plasmon coupling circular grating can be modulated by the nonlinear-variant width and linear-variant depth. The simulation result indicates that the different relative phase of emitting light lead to variant focal length. We firstly show a unique phenomenon for the linear-variant depths and nonlinear-variant widths of circular grating that the positive change and negative ...

  9. Verification of the NIKE3D structural analysis code by comparison against the analytic solution for a spherical cavity under a far-field uniaxial stress

    Energy Technology Data Exchange (ETDEWEB)

    Kansa, E.J.

    1989-01-01

    The original scope of this task was to simulate the stresses and displacements of a hard rock tunnel experimental design using a suitable three-dimensional finite element code. NIKE3D was selected as a suitable code for performing these primarily approximate linearly elastic 3D analyses, but it required modifications to include initial stress, shear traction boundary condition and excavation options. During the summer of 1988, such capabilities were installed in a special version of NIKE3D. Subsequently, we verified both the LLNL's commonly used version of NIKE3D and our private modified version against the analytic solution for a spherical cavity in an elastic material deforming under a far-field uniaxial stress. We find the results produced by the unmodified and modified versions of NIKE3D to be in good agreement with the analytic solutions, except near the cavity, where the errors in the stress field are large. As can be expected from a code based on a displacement finite element formulation, the displacements are much more accurate than the stresses calculated from the 8-noded brick elements. To reduce these errors to acceptable levels, the grid must be refined further near the cavity wall. The level of grid refinement required to simulate accurately tunneling problems that do not have spatial symmetry in three dimensions using the current NIKE3D code is likely to exceed the memory capacity of the largest CRAY 1 computers at LLNL. 8 refs., 121 figs.

  10. Experimental Testing of Nonredundant Near-Field to Far-Field Transformations with Spherical Scanning Using Flexible Modellings for Nonvolumetric Antennas

    Directory of Open Access Journals (Sweden)

    Francesco D'Agostino

    2013-01-01

    Full Text Available This paper deals with the experimental testing of effective probe compensated near-field-far-field (NF-FF transformations with spherical scanning requiring a minimum number of NF data. They rely on nonredundant sampling representations of the voltage measured by the probe, based on very flexible source modellings suitable for nonvolumetric antennas characterized by two dimensions very different from the other one. In particular, a cylinder ended in two half-spheres is adopted for modelling long antennas, whereas the quasi-planar ones are considered as enclosed in a rotational surface formed by two circular “bowls” having the same aperture diameter, but eventually different bending radii. The NF data needed to perform the classical spherical NF-FF transformation are then accurately and efficiently retrieved from the acquired nonredundant ones via optimal sampling interpolation formulas. A remarkable reduction of the number of the required NF data and, as a consequence, a significant measurement time saving can be so obtained. The experimental tests have been carried out at Antenna Characterization Lab of the University of Salerno and both the NF and FF reconstructions are resulted to be very good, thus confirming the accuracy and reliability of these NF-FF transformations from the experimental viewpoint too.

  11. Failure Patterns After Hemithoracic Pleural Intensity Modulated Radiation Therapy for Malignant Pleural Mesothelioma

    Energy Technology Data Exchange (ETDEWEB)

    Rimner, Andreas, E-mail: rimnera@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Spratt, Daniel E. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Zauderer, Marjorie G. [Department of Medicine, Thoracic Oncology Service, Memorial Sloan-Kettering Cancer Center, Weill Cornell Medical College, New York, New York (United States); Rosenzweig, Kenneth E. [Department of Radiation Oncology, Mount Sinai Medical Center, New York, New York (United States); Wu, Abraham J.; Foster, Amanda [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Yorke, Ellen D. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Adusumilli, Prasad; Rusch, Valerie W. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Krug, Lee M. [Department of Medicine, Thoracic Oncology Service, Memorial Sloan-Kettering Cancer Center, Weill Cornell Medical College, New York, New York (United States)

    2014-10-01

    Purpose: We previously reported our technique for delivering intensity modulated radiation therapy (IMRT) to the entire pleura while attempting to spare the lung in patients with malignant pleural mesothelioma (MPM). Herein, we report a detailed pattern-of-failure analysis in patients with MPM who were unresectable or underwent pleurectomy/decortication (P/D), uniformly treated with hemithoracic pleural IMRT. Methods and Materials: Sixty-seven patients with MPM were treated with definitive or adjuvant hemithoracic pleural IMRT between November 2004 and May 2013. Pretreatment imaging, treatment plans, and posttreatment imaging were retrospectively reviewed to determine failure location(s). Failures were categorized as in-field (within the 90% isodose line), marginal (<90% and ≥50% isodose lines), out-of-field (outside the 50% isodose line), or distant. Results: The median follow-up was 24 months from diagnosis and the median time to in-field local failure from the end of RT was 10 months. Forty-three in-field local failures (64%) were found with a 1- and 2-year actuarial failure rate of 56% and 74%, respectively. For patients who underwent P/D versus those who received a partial pleurectomy or were deemed unresectable, the median time to in-field local failure was 14 months versus 6 months, respectively, with 1- and 2-year actuarial in-field local failure rates of 43% and 60% versus 66% and 83%, respectively (P=.03). There were 13 marginal failures (19%). Five of the marginal failures (38%) were located within the costomediastinal recess. Marginal failures decreased with increasing institutional experience (P=.04). Twenty-five patients (37%) had out-of-field failures. Distant failures occurred in 32 patients (48%). Conclusions: After hemithoracic pleural IMRT, local failure remains the dominant form of failure pattern. Patients treated with adjuvant hemithoracic pleural IMRT after P/D experience a significantly longer time to local and distant failure than

  12. Radiation and scattering by thin-wire structures in the complex frequency domain. [electromagnetic theory for thin-wire antennas

    Science.gov (United States)

    Richmond, J. H.

    1974-01-01

    Piecewise-sinusoidal expansion functions and Galerkin's method are employed to formulate a solution for an arbitrary thin-wire configuration in a homogeneous conducting medium. The analysis is performed in the real or complex frequency domain. In antenna problems, the solution determines the current distribution, impedance, radiation efficiency, gain and far-field patterns. In scattering problems, the solution determines the absorption cross section, scattering cross section and the polarization scattering matrix. The electromagnetic theory is presented for thin wires and the forward-scattering theorem is developed for an arbitrary target in a homogeneous conducting medium.

  13. Japanese structure survey of radiation oncology in 2005 based on institutional stratification of patterns of care study.

    Science.gov (United States)

    Teshima, Teruki; Numasaki, Hodaka; Shibuya, Hitoshi; Nishio, Masamichi; Ikeda, Hiroshi; Ito, Hisao; Sekiguchi, Kenji; Kamikonya, Norihiko; Koizumi, Masahiko; Tago, Masao; Nagata, Yasushi; Masaki, Hidekazu; Nishimura, Tetsuo; Yamada, Shogo

    2008-09-01

    To evaluate the structure of radiation oncology in Japan in terms of equipment, personnel, patient load, and geographic distribution to identify and improve any deficiencies. A questionnaire-based national structure survey was conducted between March 2006 and February 2007 by the Japanese Society of Therapeutic Radiology and Oncology. These data were analyzed in terms of the institutional stratification of the Patterns of Care Study. The total numbers of new cancer patients and total cancer patients (new and repeat) treated with radiotherapy in 2005 were estimated at approximately 162,000 and 198,000, respectively. In actual use were 765 linear accelerators, 11 telecobalt machines, 48 GammaKnife machines, 64 60Co remote-controlled after-loading systems, and 119 192Ir remote-controlled after-loading systems. The linear accelerator systems used dual-energy function in 498 systems (65%), three-dimensional conformal radiotherapy in 462 (60%), and intensity-modulated radiotherapy in 170 (22%). There were 426 Japanese Society of Therapeutic Radiology and Oncology-certified radiation oncologists, 774 full-time equivalent radiation oncologists, 117 medical physicists, and 1,635 radiation therapists. Geographically, a significant variation was found in the use of radiotherapy, from 0.9 to 2.1 patients/1,000 population. The annual patient load/FTE radiation oncologist was 247, exceeding the Blue Book guidelines level. Patterns of Care Study stratification can clearly discriminate the maturity of structures according to their academic nature and caseload. The Japanese structure has clearly improved during the past 15 years in terms of equipment and its use, although the shortage of manpower and variations in maturity disclosed by this Patterns of Care Study stratification remain problematic. These constitute the targets for nationwide improvement in quality assurance and quality control.

  14. Physically-based modeling of topographic effects on spatial evapotranspiration and soil moisture patterns through radiation and wind

    Directory of Open Access Journals (Sweden)

    M. Liu

    2012-02-01

    Full Text Available In this paper, simulations with the Soil Water Atmosphere Plant (SWAP model are performed to quantify the spatial variability of both potential and actual evapotranspiration (ET, and soil moisture content (SMC caused by topography-induced spatial wind and radiation differences. To obtain the spatially distributed ET/SMC patterns, the field scale SWAP model is applied in a distributed way for both pointwise and catchment wide simulations. An adapted radiation model from r.sun and the physically-based meso-scale wind model METRAS PC are applied to obtain the spatial radiation and wind patterns respectively, which show significant spatial variation and correlation with aspect and elevation respectively. Such topographic dependences and spatial variations further propagate to ET/SMC. A strong spatial, seasonal-dependent, scale-relevant intra-catchment variability in daily/annual ET and less variability in SMC can be observed from the numerical experiments. The study concludes that topography has a significant effect on ET/SMC in the humid region where ET is a energy limited rather than water availability limited process. It affects the spatial runoff generation through spatial radiation and wind, therefore should be applied to inform hydrological model development. In addition, the methodology used in the study can serve as a general method for physically-based ET estimation for data sparse regions.

  15. Accurate numerical simulation of the far-field tsunami caused by the 2011 Tohoku earthquake, including the effects of Boussinesq dispersion, seawater density stratification, elastic loading, and gravitational potential change

    Science.gov (United States)

    Baba, Toshitaka; Allgeyer, Sebastien; Hossen, Jakir; Cummins, Phil R.; Tsushima, Hiroaki; Imai, Kentaro; Yamashita, Kei; Kato, Toshihiro

    2017-03-01

    In this study, we considered the accurate calculation of far-field tsunami waveforms by using the shallow water equations and accounting for the effects of Boussinesq dispersion, seawater density stratification, elastic loading, and gravitational potential change in a finite difference scheme. By comparing numerical simulations that included and excluded each of these effects with the observed waveforms of the 2011 Tohoku tsunami, we found that all of these effects are significant and resolvable in the far field by the current generation of deep ocean-bottom pressure gauges. Our calculations using previously published, high-resolution models of the 2011 Tohoku tsunami source exhibited excellent agreement with the observed waveforms to a degree that has previously been possible only with near-field or regional observations. We suggest that the ability to model far-field tsunamis with high accuracy has important implications for tsunami source and hazard studies.

  16. Low frequency interference between short synchrotron radiation sources

    Directory of Open Access Journals (Sweden)

    F. Méot

    2001-06-01

    Full Text Available A recently developed analytical formalism describing low frequency far-field synchrotron radiation (SR is applied to the calculation of spectral angular radiation densities from interfering short sources (edge, short magnet. This is illustrated by analytical calculation of synchrotron radiation from various assemblies of short dipoles, including an “isolated” highest density infrared SR source.

  17. Radiation damping in metal nanoparticle pairs.

    Science.gov (United States)

    Dahmen, Christian; Schmidt, Benjamin; von Plessen, Gero

    2007-02-01

    The radiation damping rate of plasmon resonances in pairs of spherical gold nanoparticles is calculated. The radiative line width of the plasmon resonance indicates significant far-field coupling between the nanoparticles over distances many times the particle diameter. The radiation damping of the coupled particle-plasmon mode alternates between superradiant and subradiant behavior when the particle spacing is varied. At small particle spacings where near-field coupling occurs, the radiation damping rate lies far below that of an isolated particle.

  18. Simulation study of the effects of near- and far-field heating during focused ultrasound uterine fibroid ablation using an electronically focused phased array: A theoretical analysis of patient safety

    Energy Technology Data Exchange (ETDEWEB)

    Ellens, Nicholas, E-mail: nicholas.ellens@utoronto.ca; Hynynen, Kullervo [Sunnybrook Research Institute, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7 (Canada)

    2014-07-15

    Purpose: Assess the feasibility of using large-aperture, flat ultrasonic transducer arrays with 6500 small elements operating at 500 kHz without the use of any mechanical components for the thermal coagulation of uterine fibroids. This study examines the benefits and detriments of using a frequency that is significantly lower than that used in clinical systems (1–1.5 MHz). Methods: Ultrasound simulations were performed using the anatomies of five fibroid patients derived from 3D MRI. Using electronic steering solely, the ultrasound focus from a flat, 6500-element phased array was translated around the volume of the fibroids in various patterns to assess the feasibility of completing full treatments from fixed physical locations. Successive temperature maps were generated by numerically solving the bioheat equation. Using a thermal dose model, the bioeffects of these simulations were quantified and analyzed. Results: The simulations indicate that such an array could be used to perform fibroid treatments to 18 EM{sub 43} at an average rate of 90 ± 20 cm{sup 3}/h without physically moving the transducer array. On average, the maximum near-field thermal dose for each patient was below 4 EM{sub 43}. Fibroid tissue could be treated as close as 40 mm to the spine without reaching temperatures expected to cause pain or damage. Conclusions: Fibroids were successfully targeted and treated from a single transducer position to acceptable extents and without causing damage in the near- or far-field. Compared to clinical systems, treatment rates were good. The proposed treatment paradigm is a promising alternative to existing systems and warrants further investigation.

  19. Far-field sorption data bases for performance assessment of a L/ILW repository in an undisturbed Palfris marl host rock

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.H.; Baeyens, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-12-01

    A Palfris marl formation at Wellenberg (Gemeinde Wolfenschiessen, NW) has been chosen by NAGRA as a potential repository site for low- and intermediate-level radioactive waste, L/ILW. In the coming years a series of performance assessment studies will be performed for this site. One set of key data required for such safety analysis calculations is sorption data bases (SDB) for safety relevant radionuclides in the far-field. The purpose of this report is to describe the procedures used to generate sorption data bases appropriate for the in situ conditions existing along the different potential flow paths in an undisturbed marl host rock formation. An important aim was to document the sources of sorption data used and, in particular, the processes by which data selections were mad.e. The main guiding principles here were `transparency` and `traceability`. Inherent within this whole process is also the justification for, and defensibility of, the selected values. Much of the sorption data used to generate the SDB for marl came from the open literature. A major part of this report is concerned with describing the procedures whereby these initial literature values are modified so that they apply to the actual marl mineralogies and groundwater chemistries. The resulting `reference R{sub d} values` are then further modified using so called Lab -> Field transfer factors to produce sorption values which are appropriate to the in situ bulk rock conditions. The Lab -> Field transfer factors attempt to correct for the differences in sorption site availability between the crushed rock state used in batch tests and the intact rock state existing in reality in the host rock. There are two main groundwater chemistries and five characteristic mineralogical compositions which cover the three broad types of flow paths which have been identified in the Palfris marl formation. In principle the methodology described here to construct sorption data bases for marl is applicable to any

  20. Process and pattern in cichlid radiations - inferences for understanding unusually high rates of evolutionary diversification.

    Science.gov (United States)

    Seehausen, Ole

    2015-07-01

    The cichlid fish radiations in the African Great Lakes differ from all other known cases of rapid speciation in vertebrates by their spectacular trophic diversity and richness of sympatric species, comparable to the most rapid angiosperm radiations. I review factors that may have facilitated these radiations and compare these with insights from recent work on plant radiations. Work to date suggests that it was a coincidence of ecological opportunity, intrinsic ecological versatility and genomic flexibility, rapidly evolving behavioral mate choice and large amounts of standing genetic variation that permitted these spectacular fish radiations. I propose that spatially orthogonal gradients in the fit of phenotypes to the environment facilitate speciation because they allow colonization of alternative fitness peaks during clinal speciation despite local disruptive selection. Such gradients are manifold in lakes because of the interaction of water depth as an omnipresent third spatial dimension with other fitness-relevant variables. I introduce a conceptual model of adaptive radiation that integrates these elements and discuss its applicability to, and predictions for, plant radiations. © 2015 The Author. New Phytologist © 2015 New Phytologist Trust.

  1. Patterns of Failure After Concurrent Bevacizumab and Hypofractionated Stereotactic Radiation Therapy for Recurrent High-Grade Glioma

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, Lauren Q. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Beal, Kathryn, E-mail: bealk@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Goenka, Anuj [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Karimi, Sasan [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Iwamoto, Fabio M. [Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Yamada, Yoshiya [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Zhang, Zhigang [Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Lassman, Andrew B.; Abrey, Lauren E. [Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Gutin, Philip H. [Department of Neurosurgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2013-03-01

    Purpose: Concurrent bevacizumab with hypofractionated stereotactic radiation therapy (HSRT) is safe and effective for the treatment of recurrent high-grade gliomas (HGG). The objective of this study was to characterize the patterns of failure after this treatment regimen. Methods and Materials: Twenty-four patients with recurrent enhancing HGG were previously treated on an institutional review board-approved protocol of concurrent bevacizumab and reirradiation. Patients received 30 Gy in 5 fractions to the recurrent tumor with HSRT. Brain magnetic resonance imaging (MRI) was performed every 2 cycles, and bevacizumab was continued until clinical or radiographic tumor progression according to the criteria of Macdonald et al. MRI at the time of progression was fused to the HSRT treatment plan, and the location of recurrence was classified on the basis of volume within the 95% isodose line. Outcomes based on patient characteristics, tumor grade, recurrence pattern, and best response to treatment were analyzed by the Kaplan-Meier method. Results: Twenty-two patients experienced either clinical or radiographic progression. Recurrent tumor was enhancing in 15 (71.4%) and nonenhancing in 6 (28.6%) patients. Eleven patients (52.4%) had recurrence within the radiation field, 5 patients (23.8%) had marginal recurrence, and 5 patients had recurrence outside the radiation field. Pattern of enhancement and location of failure did not correlate with overall survival or progression-free survival. Radiographic response was the only variable to significantly correlate with progression-free survival. Conclusions: Despite the promising initial response seen with the addition of HSRT to bevacizumab as salvage treatment for recurrent HGG, approximately half of patients ultimately still experience failure within the radiation field. The rate of local failure with the addition of HSRT seems to be lower than that seen with bevacizumab alone in the salvage setting. Our data underscore the

  2. Effects of UV-B radiation on phenolic composition and deposition patterns and leaf physiology in three Eastern tree species

    Science.gov (United States)

    Sullivan, Joseph H.; Gitz, Dennis C.; Peek, Michael S.; McElrone, Andrew J.

    2002-01-01

    Quantitative changes in foliar chemistry in response to UVB radiation are frequently reported but less is known about the qualitative changes in putative UV-screening compounds. It has also not been conclusively shown whether qualitative differences in screening compounds or differences in localization patterns influences the sensitivity of plants to damage from UVB radiation. In this study we evaluated the chemical composition and deposition patterns of UV-absorbing compounds in three tree species and assayed these species for possible effects on gas exchange and photosynthetic carbon assimilation. Branches of mature trees of sweetgum (Liquidambar styraciflua), tulip poplar (Liriodendron tulipifera) and red maple (Acer rubrum) were exposed to supplemental levels of UVB radiation over three growing seasons. Controls for UVA were also measured by exposing branches to supplemental UVA only, and additional branches not irradiated were also used for controls. These species demonstrated contrasting chemical composition and deposition patterns with poplar being the most responsive in terms of epidermal accumulation of phenolics including flavonols and chlorogenic acid and hydroxycinnamates. Sweetgum and red maple showed increases primarily in hydroxycinnamates, particularly in the mesophyll in red maple. Leaf area was marginally influenced by UV exposure level. Assimilation was generally not reduced by UVB radiation in these species and was enhanced in red maple by both UVB and UVA and by UVA in sweetgum. These finding are consistent with a hypothesis that epidermal attenuation of UVB would only be reduced in poplar, which accumulated the additional epidermal screening compounds. It is possible that photosynthetic efficiency was enhanced in red maple by the increased absorption of blue light within the mesophyll. Stomatal conductance was generally reduced, and this led to an increase in water use efficiency in red maple and poplar.

  3. A Simple Method to Stabilize Radiation Pattern over a Large Bandwidth

    Directory of Open Access Journals (Sweden)

    Haiyang Zhang

    2014-01-01

    Full Text Available An alternative radiation stabilization method has been presented for patch antenna. With this method, side radiation could be suppressed when a conductor ring and a circular slot both with the width of a quarter-wavelength are placed on the same layer and around patch antenna. An experimental structure has been simulated and the distance l from antenna part to conductor ring is optimized using parametric function of HFSS software. Measured results given in this paper obviously indicate that not only the side radiation from the boundary of substrate could be suppressed effectively, but also the antenna directivity could be adjusted and enhanced after this method has been carried out. Both simulation and measurement indicate that when the distance l is set to one guided wavelength (λg, side radiation could be suppressed the most effectively and the return loss of patch antenna is only slightly affected.

  4. The radiative zone of the Sun and the tachocline: stability of baroclinic patterns of differential rotation

    CERN Document Server

    Caleo, Andrea

    2016-01-01

    Barotropic rotation and radiative equilibrium are mutually incompatible in stars. The issue is often addressed by allowing for a meridional circulation, but this is not devoid of theoretical complications. Models of rotation in the Sun which maintain strict radiative equilibrium, making use of the observation that the Sun is not in a state of barotropic rotation, have recently been suggested. To investigate the dynamical behaviour of these solutions, we study the local stability of stratified, weakly magnetized, differentially rotating fluids to non-axisymmetric perturbations. Finite heat conductivity, kinematic viscosity, and resistivity are present. The evolution of local embedded perturbations is governed by a set of coupled, ordinary differential equations with time-dependent coefficients. Two baroclinic models of rotation for the upper radiative zone and tachocline are studied: (i) an interpolation based on helioseismology data, (ii) a theoretical solution directly compatible with radiative equilibrium. ...

  5. Normal tissue studies in radiation oncology: A systematic review of highly cited articles and citation patterns

    OpenAIRE

    Nieder, Carsten; Andratschke, Nicolaus H.; GROSU, ANCA L.

    2014-01-01

    Radiation therapy is one of the cornerstones of modern multidisciplinary cancer treatment. Normal tissue tolerance is critical as radiation-induced side effects may compromise organ function and quality of life. The importance of normal tissue research is reflected by the large number of scientific articles, which have been published between 2006 and 2010. The present study identified important areas of research as well as seminal publications. The article citation rate is among the potential...

  6. RELATIONSHIP BETWEEN LANDCOVER PATTERN AND SURFACE NET RADIATION IN AN COASTAL CITY

    OpenAIRE

    Zhao, X.; Liu, L.; X. Liu; Zhao, Y

    2016-01-01

    Taking Xiamen city as the study area this research first retrieved surface net radiation using meteorological data and Landsat 5 TM images of the four seasons in the year 2009. Meanwhile the 65 different landscape metrics of each analysis unit were acquired using landscape analysis method. Then the most effective landscape metrics affecting surface net radiation were determined by correlation analysis, partial correlation analysis, stepwise regression method, etc. At both class and landscape ...

  7. A Compact Single-Feed Circularly Polarized Microstrip Antenna with Symmetric and Wide-Beamwidth Radiation Pattern

    Directory of Open Access Journals (Sweden)

    Xihong Ye

    2013-01-01

    Full Text Available A compact single-feed circularly polarized microstrip antenna is proposed to achieve symmetric radiation pattern over a wide range of observation angles. In order to reduce the radiation aperture and consequently broaden the circular polarization (CP and the half power beamwidth (HPBW of the antenna, a partially etched superstrate and a conducting cavity are employed in the design. Further, reasonable axial ratio (AR and impedance bandwidths are realized within the compact structure by using a simple series crossed-slot aperture coupled feeding. As a consequence, the overall dimension of the fabricated prototype is 0.32λ0 × 0.32λ0 × 0.12λ0 at the center operating frequency of 1.56 GHz, and a 3.0% overlapped bandwidth of 10 dB return loss (RL and 3 dB AR is obtained. Within the bandwidth, symmetric CP radiation pattern over almost the entire upper hemisphere is observed and the HPBW is also increased from 60° to 106°.

  8. Dependence of fading patterns of photo-stimulated luminescence from imaging plates on radiation, energy, and image reader

    CERN Document Server

    Ohuchi, H

    2002-01-01

    We have been investigating the fading characteristics of imaging plates (IPs) as integral type detectors. The dependence on alpha, beta, and gamma ray radiation and their energies of the fading effect was measured using three types of IPs (BAS-UR, BAS-TR, and BAS-MS). The functions to correct the fading were determined by using the method reported in a previous paper. In all types of IPs, we confirmed that the fading effect is independent of the energy of the incident particles of beta and gamma rays and also independent of radiation except for the first component, which fades out in a very short time after irradiation with alpha rays. These results are very useful in the utilization of IPs as integral detectors in practical radiation fields. Empirically, the fading pattern is known to change when the IP is scanned by different types of image readers. The differences in the fading patterns obtained with two types of image readers, the BAS-1000 and the BAS-5000 (Fuji Film Co.), is discussed. Development of an ...

  9. Spontaneous tunable Turing pattern formation for coherent high-power THz radiation

    CERN Document Server

    Huang, Shu-Wei; Yang, Shang-Hua; Yu, Mingbin; Kwong, Dim-Lee; Zelevinsky, T; Jarrahi, Mona; Wong, Chee Wei

    2016-01-01

    The spontaneous breaking of symmetry and homogeneity through dissipative pattern formation is a fundamental question in developmental biology, molecular biochemistry, mathematics and nonlinear physics. Self-organized patterns arise in nature, such as pigmentation in animals, tree branching fractals, Prigogine non-equilibrium chemical bifurcations, and are postulated by Turing to occur from diffusion-reaction driven instabilities. In spite of the spontaneous nature, these threshold-dependent patterns - when formed - can potentially be remarkably robust in the presence of noise. Here we report the spontaneous Turing pattern formation in chip-scale nonlinear oscillators, developing a precision frequency comb in the solid-state. The stationary Turing pattern is discretely tunable across 430 GHz on a THz carrier, with a sideband non-uniformity measured down to 1 part in 1.5x10^15. Local mode hybridizations in the nonlinear ring oscillator seeds the coherent pattern formation and phase matching, to obtain a record ...

  10. FDTD analysis of human body-core temperature elevation due to RF far-field energy prescribed in the ICNIRP guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Akimasa; Asano, Takayuki; Fujiwara, Osamu [Department of Computer Science and Engineering, Nagoya Institute of Technology (Japan)

    2007-08-21

    This study investigated the relationship between the specific absorption rate and temperature elevation in an anatomically-based model named NORMAN for exposure to radio-frequency far fields in the ICNIRP guidelines (1998 Health Phys. 74 494-522). The finite-difference time-domain method is used for analyzing the electromagnetic absorption and temperature elevation in NORMAN. In order to consider the variability of human thermoregulation, parameters for sweating are derived and incorporated into a conventional sweating formula. First, we investigated the effect of blood temperature variation modeling on body-core temperature. The computational results show that the modeling of blood temperature variation was the dominant factor influencing the body-core temperature. This is because the temperature in the inner tissues is elevated via the circulation of blood whose temperature was elevated due to EM absorption. Even at different frequencies, the body-core temperature elevation at an identical whole-body average specific absorption rate (SAR) was almost the same, suggesting the effectiveness of the whole-body average SAR as a measure in the ICNIRP guidelines. Next, we discussed the effect of sweating on the temperature elevation and thermal time constant of blood. The variability of temperature elevation caused by the sweating rate was found to be 30%. The blood temperature elevation at the basic restriction in the ICNIRP guidelines of 0.4 W kg{sup -1} is 0.25 {sup 0}C even for a low sweating rate. The thermal time constant of blood temperature elevation was 23 min and 52 min for a man with a lower and a higher sweating rate, respectively, which is longer than the average time of the SAR in the ICNIRP guidelines. Thus, the whole-body average SAR required for blood temperature elevation of 1 {sup 0}C was 4.5 W kg{sup -1} in the model of a human with the lower sweating coefficients for 60 min exposure. From a comparison of this value with the basic restriction in the

  11. Research and Implementation of Far Field Antenna Testing System%远场天线测试系统的研究与实现

    Institute of Scientific and Technical Information of China (English)

    江思杰; 程照明; 江传华

    2014-01-01

    Aiming at the process and requirements of antenna parameters test, we analyze the main problems in the antenna parameters test, study the influence of environmental factors on measurements in the actual test process, and propose a design of an automatic test system based on virtual instrument technology for far field antenna performance parameters. We elaborate the system components and working principles, including the control principles of a vector network analyzer, an antenna test turntable and a derrick and the timing design of data acquisition. Combined with Matlab, we realize the error compensation of affecting factors and the testing calculation methods of antenna performance parameters, use da-tabase technology to accomplish antenna test data storage, read and report printing, and verify the reliability and feasibility of the scheme through field test experiment.%针对天线参数测试过程及测试要求,分析天线参数测试中的主要问题,研究实际测试过程中环境因素对天线参数测量结果的影响,提出了一种基于虚拟仪器技术的远场天线性能参数自动测试系统的设计方案,详细阐述了该方案的系统组成部分与工作原理,包括矢量网络分析仪、天线测试转台与吊杆的控制原理以及数据采集的时序设计,结合Matlab实现了对影响因素的误差补偿与天线性能参数的测试计算方法,利用数据库技术实现天线测试数据的存储、读取与报告打印,通过现场测试试验验证了该方案的可靠性与可行性。

  12. FDTD analysis of human body-core temperature elevation due to RF far-field energy prescribed in the ICNIRP guidelines

    Science.gov (United States)

    Hirata, Akimasa; Asano, Takayuki; Fujiwara, Osamu

    2007-08-01

    This study investigated the relationship between the specific absorption rate and temperature elevation in an anatomically-based model named NORMAN for exposure to radio-frequency far fields in the ICNIRP guidelines (1998 Health Phys. 74 494-522). The finite-difference time-domain method is used for analyzing the electromagnetic absorption and temperature elevation in NORMAN. In order to consider the variability of human thermoregulation, parameters for sweating are derived and incorporated into a conventional sweating formula. First, we investigated the effect of blood temperature variation modeling on body-core temperature. The computational results show that the modeling of blood temperature variation was the dominant factor influencing the body-core temperature. This is because the temperature in the inner tissues is elevated via the circulation of blood whose temperature was elevated due to EM absorption. Even at different frequencies, the body-core temperature elevation at an identical whole-body average specific absorption rate (SAR) was almost the same, suggesting the effectiveness of the whole-body average SAR as a measure in the ICNIRP guidelines. Next, we discussed the effect of sweating on the temperature elevation and thermal time constant of blood. The variability of temperature elevation caused by the sweating rate was found to be 30%. The blood temperature elevation at the basic restriction in the ICNIRP guidelines of 0.4 W kg-1 is 0.25 °C even for a low sweating rate. The thermal time constant of blood temperature elevation was 23 min and 52 min for a man with a lower and a higher sweating rate, respectively, which is longer than the average time of the SAR in the ICNIRP guidelines. Thus, the whole-body average SAR required for blood temperature elevation of 1 °C was 4.5 W kg-1 in the model of a human with the lower sweating coefficients for 60 min exposure. From a comparison of this value with the basic restriction in the ICNIRP guidelines of 0

  13. Light extraction enhancement with radiation pattern shaping of LEDs by waveguiding nanorods with impedance-matching tips.

    Science.gov (United States)

    Hsiao, Yu-Hsuan; Chen, Cheng-Ying; Huang, Li-Chuan; Lin, Guan-Jhong; Lien, Der-Hsien; Huang, Jian-Jang; He, Jr-Hau

    2014-03-07

    Syringe-like ZnO nanorods (NRs) were fabricated on InGaN/GaN light emitting diodes (LEDs) by a hydrothermal method. Without sacrificing the electrical performances of LEDs, syringe-like NRs can enhance light extraction capability by 10.5% at 20 mA and shape the radiation profile with a view angle collimated from 136° to 121°. By performing optical experiments and simulation, it is found that the superior light extraction efficiency with a more collimated radiation pattern is attributed to the waveguiding effect of NRs and the mitigation of abrupt index change by the tapered ends of syringe-like ZnO NRs. This work demonstrates the importance of the nanostructure morphology in LED performances and provides the architecture design guidelines of nanostructures to a variety of optical devices.

  14. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Directory of Open Access Journals (Sweden)

    Shilei Liu

    2017-07-01

    Full Text Available Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF and acoustic streaming (AS. In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV. Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning.

  15. Relationship Between Far Field Stresses, Fluid Flow and High-Pressure Deserpentinization in Subducting Slabs: a Case Study From the Almirez Ultramafic Massif

    Science.gov (United States)

    Dilissen, Nicole; Hidas, Károly; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Kahl, Wolf-Achim; Padrón-Navarta, José Alberto; Jesús Román-Alpiste, Manuel

    2017-04-01

    Serpentinite dehydration during prograde metamorphism plays a crucial role in subduction dynamics. Observations from exhumed paleo-subduction metamorphic terranes suggest that the discharge of deserpentinization fluids from the subducting slab takes place along different pathways and mechanisms [e.g. 1-3]. Analysis of intermediate-depth focal solutions in active subduction zones indicates that slabs are subjected to different principal stress fields characterized primarily by downdip compression and downdip tension [4]. Although it is well known that far field stresses play a crucial role on fluid flow channeling, their potential impact on the kinetics of serpentinite dehydration and subsequent fluid escape in subducting slabs is still poorly understood. Here, we present a detailed structural and microstructural study to investigate the relationships between far field stresses, fluid flow and high-pressure deserpentinization in the Almirez ultramafic massif (Betic Cordillera, SE Spain) [1, 2]. This massif preserves the high-pressure breakdown of antigorite (Atg-) serpentinite to prograde chlorite (Chl-) harzburgite, which are separated by a sharp isograd [2, 5]. The Chl-harzburgite reaction products show either a granofels or spinifex-like texture indicating crystallization under different overstepping of the Atg-out reaction. The two different textural types of Chl-harzburgite occur below the Atg-out isograd as alternating, meter-wide lenses with either a granofels or spinifex texture. From field measurements, we infer that during antigorite dehydration the minimum compressive stress was subnormal to the dehydration front and the paleo-slab surface. This stress field is consistent with subduction zones with slabs under downdip compression at intermediate depths [4]. The detailed microstructural study —combining µ-CT and EBSD-SEM [6]— of Chl-harzburgite across a c. 15 m wide lens reveals that the SPO and CPO of olivines with contrasting textures are strongly

  16. Model and analysis on electromagnetic radiation of flyback power supply by FDTD simulation%反激式变换器电磁辐射的FDTD仿真与分析

    Institute of Scientific and Technical Information of China (English)

    赵全斌; 付琦; 和军平

    2011-01-01

    Electromagnetic radiation emission from a switched mode power supply is easily exceeding EMC standard limits and this phenomenon is difficult to debug for many switched mode power supply designers. It is very necessa ry to study electromagnetic radiation mechanism, characteristics and prediction method for industrial community and academia. After analyzing and modeling of some active and reactive components, such as capacitor, transformer, diode, MOSFET, PCB traces, input/output cords, a FDTD model of a flyback SMPS is set up. The distribution pattern and magnitude characteristics of far-field electromagnetic radiation are simulated and analyzed based on X FDTD software. Using simulation tool, it is found that input and output cables have a significant influence on the far-field electromagnetic radiation distribution of the flyback power supply in 30MHz-300MHz. The capability of a common mode EMI choke to inhibit radiation is verified by using simulation. This paper is useful for SMPS engi neers to design and decrease far-field electromagnetic radiation.%开关电源电磁辐射发射容易超出EMC标准限值,有必要对其形成机理、特性和预测进行研究.本文在建立电容、变压器、PCB引线、半导体开关等元器件模型基础上,对Flyback开关电源进行了时域有限差分(FDTD)建模,仿真研究了其在开放空间中远场电磁辐射的分布和规律.仿真结果表明开关电源输入/输出电缆是电磁辐射的主要影响因素,并验证了共模电感对远场电磁辐射的抑制作用.

  17. Patterns in ultraviolet radiation sensitivity of tropical, temperate and Arctic marine macroalgae

    NARCIS (Netherlands)

    van de Poll, Willem Hendrik

    2003-01-01

    Marine macroalgae on rocky substrates are an important component of the coastal ecosystem in terms of biomass and diversity. Because macroalgae depend on sunlight to drive photosynthesis they also face exposure to harmful ultraviolet-B radiation (UVBR: 280-315 nm). UVBR induces DNA damage (mainly cy

  18. Cosmic radiation and airline pilots. Exposure patterns of Norwegian SAS-pilots 1960 to 1994

    Energy Technology Data Exchange (ETDEWEB)

    Tveten, U.

    1997-02-01

    The work which is presented in this report is part of a Norwegian epidemiological project, carried out in cooperation between Institutt for Energiteknikk (IFE), the Norwegian Cancer Registry (NCR) and the Norwegian Radiation Protection Authority (NRPA). The project has been partially financed by the Norwegian Research Council. Originating from the Norwegian project, a number of similar projects have been started or are in the planning stage in a number of European countries. The present report lays the ground for estimation of individual exposure histories to cosmic radiation of pilots employed by the Scandinavian Airline System (SAS). The results presented in this report (radiation doserates for the different types of aircraft in the different years) will, in a later stage of the project, be utilized to estimate the individual radiation exposure histories. The major sources of information used as basis for this work is the collection of old SAS time tables found in the SAS Museum at Fornebu Airport in Oslo, and information provided by members of the Pilots Associations.

  19. Patterns in ultraviolet radiation sensitivity of tropical, temperate and Arctic marine macroalgae

    NARCIS (Netherlands)

    van de Poll, Willem Hendrik

    2003-01-01

    Marine macroalgae on rocky substrates are an important component of the coastal ecosystem in terms of biomass and diversity. Because macroalgae depend on sunlight to drive photosynthesis they also face exposure to harmful ultraviolet-B radiation (UVBR: 280-315 nm). UVBR induces DNA damage (mainly cy

  20. Cosmic radiation and airline pilots. Exposure patterns of Norwegian pilots flying aircraft not used by SAS

    Energy Technology Data Exchange (ETDEWEB)

    Tveten, U.

    1997-05-01

    The work which is presented in this report is part of a Norwegian epidemiological project, carried out in cooperation between Institutt for Energiteknikk (IFE), the Norwegian Cancer Registry (NCR) and the Norwegian Radiation Protection Authority (NRPA). The project has been partially financed by the Norwegian Research Council. Originating from the Norwegian project, a number of similar projects have been started or are in the planning stage in a number of European countries. The present report lays the ground for estimation of individual exposure histories to cosmic radiation of pilots flying a great diversity of different aircrafts. Aircrafts that appear in the time-tables of the Scandinavian Airline System (SAS) have been treated in an earlier report. The results presented in this report (radiation doserates for the different types of aircrafts in the different years) will, in a later stage of the project be utilized to estimate the individual radiation exposure histories. The major sources of information used as basis for the work in this report is information provided by several active pilots, members of the Pilots Associations, along with calculations performed using US Federal Aviation Administration`s computer code CARI-3N. 2 refs.

  1. CO I barcoding reveals new clades and radiation patterns of Indo-Pacific sponges of the family Irciniidae (Demospongiae: Dictyoceratida.

    Directory of Open Access Journals (Sweden)

    Judith Pöppe

    Full Text Available BACKGROUND: DNA barcoding is a promising tool to facilitate a rapid and unambiguous identification of sponge species. Demosponges of the order Dictyoceratida are particularly challenging to identify, but are of ecological as well as biochemical importance. METHODOLOGY/PRINCIPAL FINDINGS: Here we apply DNA barcoding with the standard CO1-barcoding marker on selected Indo-Pacific specimens of two genera, Ircinia and Psammocinia of the family Irciniidae. We show that the CO1 marker identifies several species new to science, reveals separate radiation patterns of deep-sea Ircinia sponges and indicates dispersal patterns of Psammocinia species. However, some species cannot be unambiguously barcoded by solely this marker due to low evolutionary rates. CONCLUSIONS/SIGNIFICANCE: We support previous suggestions for a combination of the standard CO1 fragment with an additional fragment for sponge DNA barcoding.

  2. Direct Measurement of the Radiation Pattern of a Nanoantenna Dipole Array

    CERN Document Server

    Stokes, J; Munns, J W; Yu, Y; Hilton, G S; Pugh, J R; Yang, A; Collins, A; Heard, P J; Oulton, R; Sarua, A; Kuball, M; Yuan, Z H; Orr-Ewing, A J; Cryan, M J

    2012-01-01

    Scanning microphotoluminescence is used to characterise the fluorescence from a dye-loaded polymer deposited on a 5 x 5 nanoantenna dipole array. Vertical and horizontal scans show anisotropic emission patterns.

  3. Three-dimensional modelling for assessment of far-field impact of tidal stream turbine: A case study at the Anglesey Coast, Wales, UK

    Science.gov (United States)

    Li, Xiaorong; Li, Ming; Wolf, Judith

    2017-04-01

    As a response to worldwide climate change, clean non-carbon renewable energy resources have been gaining significant attention. Among a range of renewable alternatives, tidal stream energy is considered very promising; due to its consistent predictability and availability. To investigate impacts of tidal stream devices on their surroundings, prototype experiments involving small scale laboratory studies have been implemented. Computational Flow Dynamics (CFD) modelling is also commonly applied to study turbine behaviours. However, these studies focus on impacts of the turbine in the near-field scale. As a result, in order to study and predict the far-field impacts caused by the operation of turbines, large scale 2D and 3D numerical oceanography models have been used, with routines added to reflect the impacts of turbines. In comparison to 2D models, 3D models are advantageous in providing complete prediction of vertical flow structures and hence mixing in the wake of a turbine. This research aims to deliver a thorough 3D tidal stream turbine simulation system, by considering major coastal processes, i.e. current, waves and sediment transport, based on a 3D wave-current-sediment fully coupled numerical oceanography model — the Unstructured Grid Finite Volume Community Ocean Model (FVCOM). The energy extraction of turbines is simulated by adding a body force to the momentum equations. Across the water depth, the coefficient related to the additional body force is given different values according to the turbine configuration and operation to reflect the vertical variation of the turbine's impacts on the passing flow. Three turbulence perturbation terms are added to the turbulence closure to simulate the turbine-induced turbulence generation, dissipation and interference for the turbulence length-scale. Impacts of turbine operation on surface waves are also considered by modification of wave energy flux across the device. A thorough validation study is carried out in

  4. Far field tsunami simulations of the 1755 Lisbon earthquake: Implications for tsunami hazard to the U.S. East Coast and the Caribbean

    Science.gov (United States)

    Barkan, R.; ten Brink, U.S.; Lin, J.

    2009-01-01

    The great Lisbon earthquake of November 1st, 1755 with an estimated moment magnitude of 8.5-9.0 was the most destructive earthquake in European history. The associated tsunami run-up was reported to have reached 5-15??m along the Portuguese and Moroccan coasts and the run-up was significant at the Azores and Madeira Island. Run-up reports from a trans-oceanic tsunami were documented in the Caribbean, Brazil and Newfoundland (Canada). No reports were documented along the U.S. East Coast. Many attempts have been made to characterize the 1755 Lisbon earthquake source using geophysical surveys and modeling the near-field earthquake intensity and tsunami effects. Studying far field effects, as presented in this paper, is advantageous in establishing constraints on source location and strike orientation because trans-oceanic tsunamis are less influenced by near source bathymetry and are unaffected by triggered submarine landslides at the source. Source location, fault orientation and bathymetry are the main elements governing transatlantic tsunami propagation to sites along the U.S. East Coast, much more than distance from the source and continental shelf width. Results of our far and near-field tsunami simulations based on relative amplitude comparison limit the earthquake source area to a region located south of the Gorringe Bank in the center of the Horseshoe Plain. This is in contrast with previously suggested sources such as Marqu??s de Pombal Fault, and Gulf of C??diz Fault, which are farther east of the Horseshoe Plain. The earthquake was likely to be a thrust event on a fault striking ~ 345?? and dipping to the ENE as opposed to the suggested earthquake source of the Gorringe Bank Fault, which trends NE-SW. Gorringe Bank, the Madeira-Tore Rise (MTR), and the Azores appear to have acted as topographic scatterers for tsunami energy, shielding most of the U.S. East Coast from the 1755 Lisbon tsunami. Additional simulations to assess tsunami hazard to the U.S. East

  5. Normal tissue studies in radiation oncology: A systematic review of highly cited articles and citation patterns.

    Science.gov (United States)

    Nieder, Carsten; Andratschke, Nicolaus H; Grosu, Anca L

    2014-09-01

    Radiation therapy is one of the cornerstones of modern multidisciplinary cancer treatment. Normal tissue tolerance is critical as radiation-induced side effects may compromise organ function and quality of life. The importance of normal tissue research is reflected by the large number of scientific articles, which have been published between 2006 and 2010. The present study identified important areas of research as well as seminal publications. The article citation rate is among the potential indicators of scientific impact. Highly cited articles, arbitrarily defined as those with ≥15 citations, were identified via a systematic search of the citation database, Scopus. Up to 608 articles per year were published between 2006 and 2010, however, distribution, clinical prevention or mitigation studies are critical and must receive higher priority, funding and attention.

  6. The radiative zone of the Sun and the tachocline: stability of baroclinic patterns of differential rotation

    Science.gov (United States)

    Caleo, Andrea; Balbus, Steven A.

    2016-04-01

    Barotropic rotation and radiative equilibrium are mutually incompatible in stars. The issue is often addressed by allowing for a meridional circulation, but this is not devoid of theoretical complications. Models of rotation in the Sun which maintain strict radiative equilibrium, making use of the observation that the Sun is not in a state of barotropic rotation, have recently been suggested. To investigate the dynamical behaviour of these solutions, we study the local stability of stratified, weakly magnetized, differentially rotating fluids to non-axisymmetric perturbations. Finite heat conductivity, kinematic viscosity, and resistivity are present. The evolution of local embedded perturbations is governed by a set of coupled, ordinary differential equations with time-dependent coefficients. Two baroclinic models of rotation for the upper radiative zone and tachocline are studied: (i) an interpolation based on helioseismology data, (ii) a theoretical solution directly compatible with radiative equilibrium. The growth of the local Goldreich-Schubert-Fricke instability appears to be suppressed, largely because of the viscosity. An extensive exploration of wavenumber space is carried out, with and without a magnetic field. Although we easily find classical local instabilities when they ought formally to be present, for the Sun the analysis reveals neither unstable solutions, nor even solutions featuring a large transient growth. We have not ruled out larger scale or non-linear instabilities, nor have we rigorously proven local stability. But rotational configurations in close agreement with observations, generally thought to be vulnerable to the classic local Goldreich-Schubert-Fricke instability, do appear to be locally stable under rather general circumstances.

  7. Late Ordovician geographic patterns of extinction compared with simulations of astrophysical ionizing radiation damage

    CERN Document Server

    Melott, Adrian L

    2008-01-01

    Based on the intensity and rates of various kinds of intense ionizing radiation events such as supernovae and gamma-ray bursts, it is likely that the Earth has been subjected to one or more events of potential mass extinction level intensity during the Phanerozoic. These induce changes in atmospheric chemistry so that the level of Solar ultraviolet-B radiation reaching surface and near-surface waters may be approximately doubled for up to one decade. This UVB level is known from experiment to be more than enough to kill off many kinds of organisms, particularly phytoplankton. It could easily induce a crash of the photosynthetic-based food chain in the oceans. Certain regularities in the latitudinal distribution of damage are apparent in computational simulations of the atmospheric changes. It was previously proposed that the late Ordovician extinction is a candidate for a contribution from an ionizing radiation event, based on environmental selectivity in trilobites. We confront this hypothesis with data from...

  8. Magnitude and pattern of Arctic warming governed by the seasonality of radiative forcing

    Science.gov (United States)

    Bintanja, R.; Krikken, F.

    2016-12-01

    Observed and projected climate warming is strongest in the Arctic regions, peaking in autumn/winter. Attempts to explain this feature have focused primarily on identifying the associated climate feedbacks, particularly the ice-albedo and lapse-rate feedbacks. Here we use a state-of-the-art global climate model in idealized seasonal forcing simulations to show that Arctic warming (especially in winter) and sea ice decline are particularly sensitive to radiative forcing in spring, during which the energy is effectively ‘absorbed’ by the ocean (through sea ice melt and ocean warming, amplified by the ice-albedo feedback) and consequently released to the lower atmosphere in autumn and winter, mainly along the sea ice periphery. In contrast, winter radiative forcing causes a more uniform response centered over the Arctic Ocean. This finding suggests that intermodel differences in simulated Arctic (winter) warming can to a considerable degree be attributed to model uncertainties in Arctic radiative fluxes, which peak in summer.

  9. Direct writing of nano patterns with near-field enhanced laser radiation

    Science.gov (United States)

    Jersch, Johann; Demming, Frank; Hildenhagen, L. J.; Dickmann, Klaus

    1997-08-01

    Nano processing is a cornerstone technology for several future oriented applications, as for example in the fields of high density data storage, nano matching of X-ray fresnel optics, micro electronics, micro robotics and biomolecularic. However, as well known, processing in the nanometer range with laser radiation is not possible by lenses or mirrors due to diffraction limitation. Recent research work has shown, that `focusing' of laser radiation down to a few nanometer can be obtained by using lasers in combination with nearfield technology (e.g. SNOM--Scanning Nearfield Optical Microscopy, SPM--Scanning Probe Microscopy). Lateral externally illumination of SPM probe tips with laser radiation can cause tremendous intensity enhancement in the nearfield underneath the tip. A brief theoretical consideration of this effect and results of calculations based on boundary element method is done. This kind of field energy concentration we named FOLANT-technique (FOcusing of LAserradiation in the Nearfield of a Tip). The interaction area with nanometer scale can be applied for material processing even down to atomic dimensions. Using FOLANT-technique hillocks, pits and grooves with lateral dimensions down to 10 nm have been obtained on conductive substrates as well as on dielectric materials (for example polycarbonate). Our experiments have shown, that FOLANT- technique is a promising tool for various applications in nanometer material processing.

  10. Preoperative Intensity Modulated Radiation Therapy and Chemotherapy for Locally Advanced Vulvar Carcinoma: Analysis of Pattern of Relapse

    Energy Technology Data Exchange (ETDEWEB)

    Beriwal, Sushil, E-mail: beriwals@upmc.edu [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania (United States); Shukla, Gaurav; Shinde, Ashwin; Heron, Dwight E. [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania (United States); Kelley, Joseph L.; Edwards, Robert P.; Sukumvanich, Paniti; Richards, Scott; Olawaiye, Alexander B.; Krivak, Thomas C. [Division of Gynecologic Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania (United States)

    2013-04-01

    Purpose: To examine clinical outcomes and relapse patterns in locally advanced vulvar carcinoma treated using preoperative chemotherapy and intensity modulated radiation therapy (IMRT). Methods and Materials: Forty-two patients with stage I-IV{sub A} (stage I, n=3; stage II, n=13; stage III, n=23; stage IV{sub A}, n=3) vulvar cancer were treated with chemotherapy and IMRT via a modified Gynecological Oncology Group schema using 5-fluorouracil and cisplatin with twice-daily IMRT during the first and last weeks of treatment or weekly cisplatin with daily radiation therapy. Median dose of radiation was 46.4 Gy. Results: Thirty-three patients (78.6%) had surgery for resection of vulva; 13 of these patients also had inguinal lymph node dissection. Complete pathologic response was seen in 48.5% (n=16) of these patients. Of these, 15 had no recurrence at a median time of 26.5 months. Of the 17 patients with partial pathological response, 8 (47.1%) developed recurrence in the vulvar surgical site within a median of 8 (range, 5-34) months. No patient had grade ≥3 chronic gastrointestinal/genitourinary toxicity. Of those having surgery, 8 (24.2%) developed wound infections requiring debridement. Conclusions: Preoperative chemotherapy/IMRT was well tolerated, with good pathologic response and clinical outcome. The most common pattern of recurrence was local in patients with partial response, and strategies to increase pathologic response rate with increasing dose or adding different chemotherapy need to be explored to help further improve outcomes.

  11. Glucose Metabolism Gene Expression Patterns and Tumor Uptake of {sup 18}F-Fluorodeoxyglucose After Radiation Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, George D., E-mail: george.wilson@beaumont.edu [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan (United States); Beaumont BioBank, William Beaumont Hospital, Royal Oak, Michigan (United States); Thibodeau, Bryan J.; Fortier, Laura E.; Pruetz, Barbara L. [Beaumont BioBank, William Beaumont Hospital, Royal Oak, Michigan (United States); Galoforo, Sandra; Baschnagel, Andrew M.; Chunta, John [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan (United States); Oliver Wong, Ching Yee [Department of Diagnostic Radiology and Molecular Imaging Medicine, William Beaumont Hospital, Royal Oak, Michigan (United States); Yan, Di; Marples, Brian [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan (United States); Huang, Jiayi [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan (United States); Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States)

    2014-11-01

    Purpose: To investigate whether radiation treatment influences the expression of glucose metabolism genes and compromises the potential use of {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) as a tool to monitor the early response of head and neck cancer xenografts to radiation therapy (RT). Methods and Materials: Low passage head and neck squamous cancer cells (UT14) were injected to the flanks of female nu/nu mice to generate xenografts. After tumors reached a size of 500 mm{sup 3} they were treated with either sham RT or 15 Gy in 1 fraction. At different time points, days 3, 9, and 16 for controls and days 4, 7, 12, 21, 30, and 40 after irradiation, 2 to 3 mice were assessed with dynamic FDG-PET acquisition over 2 hours. Immediately after the FDG-PET the tumors were harvested for global gene expression analysis and immunohistochemical evaluation of GLUT1 and HK2. Different analytic parameters were used to process the dynamic PET data. Results: Radiation had no effect on key genes involved in FDG uptake and metabolism but did alter other genes in the HIF1α and glucose transport–related pathways. In contrast to the lack of effect on gene expression, changes in the protein expression patterns of the key genes GLUT1/SLC2A1 and HK2 were observed after radiation treatment. The changes in GLUT1 protein expression showed some correlation with dynamic FDG-PET parameters, such as the kinetic index. Conclusion: {sup 18}F-fluorodeoxyglucose positron emission tomography changes after RT would seem to represent an altered metabolic state and not a direct effect on the key genes regulating FDG uptake and metabolism.

  12. The Influence of Therapeutic Radiation on the Patterns of Bone Remodeling in Ovary-Intact and Ovariectomized Mice

    Science.gov (United States)

    Hui, Susanta K; Fairchild, Gregory R; Kidder, Louis S; Sharma, Manju; Bhattacharya, Maryka; Jackson, Scott; Le, Chap; Petryk, Anna; Islam, Mohammad Saiful; Yee, Douglas

    2013-01-01

    Purpose To characterize changes in bone remodeling associated with localized radiation that models therapeutic cancer treatment in ovary-intact and ovariectomized mice and evaluate the influence of radiation on the pattern of bone mineral remodeling. Methods Young adult, female BALB/c mice, ovary-intact (I) and ovariectomized (OVX), were used (n=71). All mice were intravenously injection with 15 μCi 45Ca. Thirty days post-45Ca administration, the hind limbs of 17 mice were exposed to a single 16 Gy radiation (R). The time course of 45Ca excretion, serum CTx and osteocalcin markers, and cancellous bone volume fraction (BV/TV) and cortical thickness (Ct.Th) of the distal femur were measured. Cellular activity and dynamic histomorphometry were performed. Results Irradiation resulted in rapid increases in fecal 45Ca excretion compared to control groups, indicating increased bone remodeling. CTX increased rapidly after irradiation, followed by an increase in osteocalcin concentration. BV/TV decreased in the ovary-intact mice following irradiation. Ct.Th increased in the OVX groups following irradiation. I+R exhibited diminished osteoblasts surface, osteoclast number and mineral apposition rate. Conclusions Our murine model showed the systemic effects (via 45Ca excretion) and local effects (via bone microarchitecture and surface activity) of clinically-relevant, therapeutic radiation exposure. Ovary-intact and ovariectomized murine models have similar 45Ca excretion but different bone microarchitecture responses. 45Ca assay effectively indicates the onset and rate of systemic bone mineral remodeling, providing real time assessment of changes in bone histomorphometric parameters. Monitoring bone health via a bone mineral marker may help identify the appropriate time for clinical intervention to preserve skeletal integrity. PMID:23314741

  13. Lineage diversity and size disparity in Musteloidea: testing patterns of adaptive radiation using molecular and fossil-based methods.

    Science.gov (United States)

    Law, Chris J; Slater, Graham J; Mehta, Rita S

    2017-05-04

    Adaptive radiation is hypothesized to be a primary mechanism that drives the remarkable species diversity and morphological disparity across the Tree of Life. Tests for adaptive radiation in extant taxa are traditionally estimated from calibrated molecular phylogenies with little input from extinct taxa. With 85 putative species in 33 genera and over 400 described extinct species, the carnivoran superfamily Musteloidea is a prime candidate to investigate patterns of adaptive radiation using both extant- and fossil-based macroevolutionary methods. The species diversity and equally impressive ecological and phenotypic diversity found across Musteloidea is often attributed to 2 adaptive radiations coinciding with 2 major climate events, the Eocene-Oligocene transition and the Mid-Miocene Climate Transition. Here, we compiled a novel time-scaled phylogeny for 88% of extant musteloids and used it as a framework for testing the predictions of adaptive radiation hypotheses with respect to rates of lineage diversification and phenotypic evolution. Contrary to expectations, we found no evidence for rapid bursts of lineage diversification at the origin of Musteloidea, and further analyses of lineage diversification rates using molecular and fossil-based methods did not find associations between rates of lineage diversification and the Eocene-Oligocene transition or Mid-Miocene Climate Transition as previously hypothesized. Rather, we found support for decoupled diversification dynamics driven by increased clade carrying capacity in the branches leading to a subclade of elongate mustelids. Supporting decoupled diversification dynamics between the subclade of elongate mustelids and the ancestral musteloid regime is our finding of increased rates of body length evolution, but not body mass evolution, within the decoupled mustelid subclade. The lack of correspondence in rates of body mass and length evolution suggest that phenotypic evolutionary rates under a single

  14. QCD radiation patterns in WH and WZ production and anomalous coupling measurements

    Energy Technology Data Exchange (ETDEWEB)

    Campanario, Francisco [Theory Division, IFIC, University of Valencia-CSIC, E-46980 Paterna, Valencia (Spain); Roth, Robin; Zeppenfeld, Dieter [Institute for Theoretical Physics, KIT, 76128 Karlsruhe (Germany)

    2015-07-01

    We present a study of QCD radiation for WH and WZ production at the LHC. Regions with high sensitivity to anomalous couplings are identified by considering the contribution of jet activity to the transverse energy. For this, WHj and WZj production cross sections are calculated at NLO QCD using the Monte Carlo program VBFNLO. Based on the observations, we propose a dynamical jet veto to enhance the sensitivity to anomalous couplings, especially in WZ production. The dynamical jet veto avoids large logarithms, which are typical for a fixed jet veto, hence, it provides more reliable predictions.

  15. Elective Nodal Irradiation and Patterns of Failure in Head and Neck Cancer After Primary Radiation Therapy

    DEFF Research Database (Denmark)

    Kjems, Julie; Gothelf, Anita B; Håkansson, Katrin

    2016-01-01

    from the surgical descriptions or computed tomography scans and compared with the original radiation treatment plan (available from 2007 onward). The p16 status was available for 282 oropharynx carcinoma cases, with 65% p16-positive. RESULTS: Of the 942 patients, 376 (40%) developed recurrences: 228....... For oropharynx carcinoma, the locoregional control rate (90% vs 70%) but not distant control rate (92% vs 87%), was significantly better in the p16-positive than in the p16-negative patients. Although fewer recurrences developed in the p16-positive group, patients with recurrence of p16-positive tumors were more...

  16. Prediction of maximum P- and S-wave amplitude distributions incorporating frequency- and distance-dependent characteristics of the observed apparent radiation patterns

    Science.gov (United States)

    Takemura, Shunsuke; Kobayashi, Manabu; Yoshimoto, Kazuo

    2016-10-01

    Frequency-dependent model of the apparent radiation pattern has been extensively incorporated into engineering and scientific applications for high-frequency seismic waves, but distance-dependent properties have not yet been fully taken into account. We investigated the unified characteristics of frequency and distance dependences in both apparent P- and S-wave radiation patterns during local crustal earthquakes. Observed distortions of the apparent P- and S-wave radiation patterns could be simply modeled by using a function of the normalized hypocentral distance, which is a product of the wave number and hypocentral distance. This behavior suggests that major cause of distortion of the apparent radiation pattern is seismic wave scattering and diffraction within the heterogeneous crust. On the basis of observed normalized hypocentral distance dependency, we proposed a method for prediction of spatial distributions of maximum P- and S-wave amplitudes. Our method incorporating normalized hypocentral distance dependence of the apparent radiation pattern reproduced the observed spatial distributions of maximum P- and S-wave amplitudes over a wide frequency and distance ranges successfully.[Figure not available: see fulltext.

  17. Ultraviolet-B and photosynthetically active radiation interactively affect yield and pattern of monoterpenes in leaves of peppermint (Mentha x piperita L.).

    Science.gov (United States)

    Behn, Helen; Albert, Andreas; Marx, Friedhelm; Noga, Georg; Ulbrich, Andreas

    2010-06-23

    Solar radiation is a key environmental signal in regulation of plant secondary metabolism. Since metabolic responses to light and ultraviolet (UV) radiation exposure are known to depend on the ratio of spectral ranges (e.g., UV-B/PAR), we examined effects of different UV-B radiation (280-315 nm) and photosynthetically active radiation (PAR, 400-700 nm) levels and ratios on yield and pattern of monoterpenoid essential oil of peppermint. Experiments were performed in exposure chambers, technically equipped for realistic simulation of natural climate and radiation. The experimental design comprised four irradiation regimes created by the combination of two PAR levels including or excluding UV-B radiation. During flowering, the highest essential oil yield was achieved at high PAR (1150 micromol m(-2) s(-1)) and approximate ambient UV-B radiation (0.6 W m(-2)). Regarding the monoterpene pattern, low PAR (550 micromol m(-2) s(-1)) and the absence of UV-B radiation led to reduced menthol and increased menthone contents and thereby to a substantial decrease in oil quality. Essential oil yield could not be correlated with density or diameter of peltate glandular trichomes, the epidermal structures specialized on biosynthesis, and the accumulation of monoterpenes. The present results lead to the conclusion that production of high quality oils (fulfilling the requirements of the Pharmacopoeia Europaea) requires high levels of natural sunlight. In protected cultivation, the use of UV-B transmitting covering materials is therefore highly recommended.

  18. Measurements of pattern formation in a confocal optical parametrical oscillator with applications in quantum optics

    DEFF Research Database (Denmark)

    Lassen, Mikael Østergaard; Buchhave, Preben

    We describe simultaneous measurements of signal/idler near field and far field patterns of a 2nd order nonlinear multi-mode parametric downconverter. We also describe the use of auto- and cross correlation techniques to obtain statistical data.......We describe simultaneous measurements of signal/idler near field and far field patterns of a 2nd order nonlinear multi-mode parametric downconverter. We also describe the use of auto- and cross correlation techniques to obtain statistical data....

  19. Testing for selection on color and pattern in a mimetic radiation

    Institute of Scientific and Technical Information of China (English)

    Justin YEAGER; Jason L.BROWN; Victor MORALES; Molly CUMMINGS; Kyle SUMMERS

    2012-01-01

    In this paper,we analyze variation in spectral reflectance and color pattern among populations to demonstrate dramatic divergence between four distinct morphs of the mimic poison frog Ranitomeya imitator.We also analyze genetic divergence in d-loop mtDNA sequences between populations.We then use coalescent-based simulations to demonstrate that the high levels of observed phenotypic divergence are not consistent with levels of genetic divergence expected under neutral drift among populations,implying an important role for selection in driving divergence between these populations.

  20. EEG patterns in persons exposed to ionizing radiation as a result of the Chernobyl accident: part 1: conventional EEG analysis.

    Science.gov (United States)

    Loganovsky, K N; Yuryev, K L

    2001-01-01

    Prospective conventional EEG study was carried out 3-5 and 10-13 years after the Chernobyl accident (1986) in patients who had acute radiation sickness and in emergency workers in 1986 ("liquidators"). Control groups comprised healthy volunteers; veterans of the Afghanistan war with posttraumatic stress disorder; veterans with mild traumatic brain injury; and patients with dyscirculatory encephalopathy. In 3-5 years after irradiation, there were irritated EEG changes with paroxysmal activity shifted to the left frontotemporal region (cortical-limbic overactivation) that were transformed 10-13 years after irradiation toward a low-voltage EEG pattern with excess of fast (beta) and slow (delta) activity together with depression of alpha and theta activity (organic brain damage with inhibition of the cortical-limbic system). Quantitative EEG is likely to be very informative for investigation of dose-effect relationships.

  1. Design of Rotating Platform Servo System for Far-field Antenna in Microwave Darkroom%微波暗室远场天线测试转台伺服系统的设计

    Institute of Scientific and Technical Information of China (English)

    余亚飞; 贾平平

    2015-01-01

    高性能天线的研发离不开一套高精度的测试系统。天线测试系统主要包括转台伺服系统、测试仪器、监控系统。其中转台伺服系统的优劣直接影响到微波暗室天线测试的准确性,因此伺服系统的设计显得十分重要。文中设计的微波暗室天线测试转台伺服系统通过ARM处理器控制电机的转动,调整被测天线的姿态的同时记录天线的天线图测试数据。系统可以自动完成远场收发双向测量,降低了测试的难度。借助频谱仪,伺服系统能够准确测量天线方向图、主瓣宽度、波瓣宽度、增益等参数。该伺服系统具有测量误差小、抗干扰能力强、测量灵敏度高等特点。随着微波暗室天线测试技术广泛应用到工业项目,该转台伺服系统具有很高的实用价值。%Development of high performance antenna depends on a high-precision test system. Antenna test system includes servo system, test equipment and monitoring system. The merit of the servo system affects the accuracy of the anechoic chamber antenna test directly. Thus,the design of the servo system is significant. Put forward an antenna pattern test servo system which controls the rotation of the mo-tor through the ARM processor,in order to record the antenna test data while adjusting the measured antenna attitude. This servo system can receive bi-far-field measurements automatically and reduce the difficulty of testing. By means of spectrum analyzer,the servo system can precisely measure antenna pattern,the beam width,the side lobe width,antenna gain and other parameters,which has a small measure-ment error,strong anti-interference ability and is capable of high sensitivity measurements. As the test of microwave anechoic chamber antenna technology is widely applied to industrial projects,this rotating servo system has very high practical value.

  2. Plamonics for Biomolecular Sensors and THz Metamaterial Waveguides (Near and Far-Field Interfaces to DNA. Guided Nanostructures from RF to Lightwave: Exploiting the Spectrum)

    Science.gov (United States)

    2014-12-17

    Task 2: SSPP DNA sensor with single-arm ‘gap’ structure or waveguide-cavity- waveguide (WCW) Task 3: MZI SSPP Architecture in DNA Bio -Sensing: Lossy...refractive index at different probe frequencies with sample load pattern D) Task 3: MZI SSPP Architecture in DNA Bio -Sensing: Lossy Scenarios The...SSPP architectures are combined with dielectric loadings with distinctive material parameters, sample differentiation can be realized by tracking the

  3. Do radiative feedbacks depend on the structure and type of climate forcing, or only on the spatial pattern of surface temperature change?

    Science.gov (United States)

    Haugstad, A.; Battisti, D. S.; Armour, K.

    2016-12-01

    Earth's climate sensitivity depends critically on the strength of radiative feedbacks linking surface warming to changes in top-of-atmosphere (TOA) radiation. Many studies use a simplistic idea of radiative feedbacks, either by treating them as global mean quantities, or by assuming they can be defined uniquely by geographic location and thus that TOA radiative response depends only on local surface warming. For example, a uniform increase in sea-surface temperature has been widely used as a surrogate for global warming (e.g., Cess et al 1990 and the CMIP 'aqua4k' simulations), with the assumption that this produces the same radiative feedbacks as those arising from a doubling of carbon dioxide - even though the spatial patterns of warming differ. However, evidence suggests that these assumptions are not valid, and local feedbacks may be integrally dependent on the structure of warming or type of climate forcing applied (Rose et al 2014). This study thus investigates the following questions: to what extent do local feedbacks depend on the structure and type of forcing applied? And, to what extent do they depend on the pattern of surface temperature change induced by that forcing? Using an idealized framework of an aquaplanet atmosphere-only model, we show that radiative feedbacks are indeed dependent on the large scale structure of warming and type of forcing applied. For example, the climate responds very differently to two forcings of equal global magnitude but applied in different global regions; the pattern of local feedbacks arising from uniform warming are not the same as that arising from polar amplified warming; and the same local feedbacks can be induced by distinct forcing patterns, provided that they produce the same pattern of surface temperature change. These findings suggest that the so-called `efficacies' of climate forcings can be understood simply in terms of how local feedbacks depend on the temperature patterns they induce.

  4. Emission and propagation of Saturn kilometric radiation: magneto-ionic modes, beaming pattern and polarization state

    CERN Document Server

    Lamy, L; Zarka, P; Canu, P; Schippers, P; Kurth, W S; Mutel, R L; Gurnett, D A; Menietti, J D; Louarn, P

    2011-01-01

    The Cassini mission crossed the source region of the Saturn kilometric radiation (SKR) on 17 October 2008. On this occasion, the Radio and Plasma Wave Science (RPWS) experiment detected both local and distant radio sources, while plasma parameters were measured in situ by the magnetometer (MAG) and the Cassini Plasma Spectrometer (CAPS). A goniopolarimetric inversion was applied to RPWS 3-antenna electric measurements to determine the wave vector k and the complete state of polarization of detected waves. We identify broadband extraordinary (X) as well as narrowband ordinary (O) mode SKR at low frequencies. Within the source region, SKR is emitted just above the X mode cutoff frequency in a hot plasma, with a typical electron-to-wave energy conversion efficiency of 1% (2% peak). The knowledge of the k-vector is then used to derive the locus of SKR sources in the kronian magnetosphere, that shows X and O components emanating from the same regions. We also compute the associated beaming angle at the source thet...

  5. Gravitational wave luminosity and net momentum flux in head-on mergers of black holes: Radiative patterns and mode mixing

    Science.gov (United States)

    Aranha, Rafael Fernandes; Soares, Ivano Damião; Tonini, Eduardo Valentino

    2016-09-01

    We show that gravitational wave radiative patterns from a point test particle falling radially into a Schwarzschild black hole, as derived by Davis, Ruffini, Press and Price [M. Davis et al., Phys. Rev. Lett. 27, 1466 (1971).], are present in the nonlinear regime of head-on mergers of black holes. We use the Bondi-Sachs characteristic formulation and express the gravitational wave luminosity and the net momentum flux in terms of the news functions. We then evaluate the (-2 )-spin-weighted ℓ-multipole decomposition of these quantities via exact expressions valid in the nonlinear regime and defined at future null infinity. Our treatment is made in the realm of Robinson-Trautman dynamics, with characteristic initial data corresponding to the head-on merger of two black holes. We consider mass ratios in the range 0.01 ≤α ≤1 . We obtain the exponential decay with ℓ of the total energy contributed by each multipole ℓ, with an accurate linear correlation in the log-linear plot of the points up to α ≃0.7 . Above this mass ratio the contribution of the odd modes to the energy decreases faster than that of the even modes, leading to the breaking of the linear correlation; for α =1 the energy in all odd modes is zero. The dominant contribution to the total radiated energy comes from the quadrupole mode ℓ=2 corresponding, for instance, to about ≃84 % for small mass ratios up to ≃99.8 % for the limit case α =1 . The total rescaled radiated energy EWtotal/m0α2 decreases linearly with decreasing α , yielding for the point particle limit α →0 the value ≃0.0484 , about 5 times larger than the result of Davis et al. [1]. The mode decomposition of the net momentum flux and of the associated gravitational wave impulses results in an adjacent-even-odd mode-mixing pattern. We obtain that the impulses contributed by each (ℓ,ℓ+1 ) mixed mode also accurately satisfy the exponential decay with ℓ, for the whole mass ratio domain considered, 0.01 ≤α 0

  6. Global-scale pattern of peatland Sphagnum growth driven by photosynthetically active radiation and growing season length

    Directory of Open Access Journals (Sweden)

    Z. Yu

    2012-07-01

    Full Text Available High-latitude peatlands contain about one third of the world's soil organic carbon, most of which is derived from partly decomposed Sphagnum (peat moss plants. We conducted a meta-analysis based on a global data set of Sphagnum growth measurements collected from published literature to investigate the effects of bioclimatic variables on Sphagnum growth. Analysis of variance and general linear models were used to relate Sphagnum magellanicum and S. fuscum growth rates to photosynthetically active radiation integrated over the growing season (PAR0 and a moisture index. We found that PAR0 was the main predictor of Sphagnum growth for the global data set, and effective moisture was only correlated with moss growth at continental sites. The strong correlation between Sphagnum growth and PAR0 suggests the existence of a global pattern of growth, with slow rates under cool climate and short growing seasons, highlighting the important role of growing season length in explaining peatland biomass production. Large-scale patterns of cloudiness during the growing season might also limit moss growth. Although considerable uncertainty remains over the carbon balance of peatlands under a changing climate, our results suggest that increasing PAR0 as a result of global warming and lengthening growing seasons, without major change in cloudiness, could promote Sphagnum growth. Assuming that production and decomposition have the same sensitivity to temperature, this enhanced growth could lead to greater peat-carbon sequestration, inducing a negative feedback to climate change.

  7. Global-scale pattern of peatland Sphagnum growth driven by photosynthetically active radiation and growing season length

    Directory of Open Access Journals (Sweden)

    Z. Yu

    2012-02-01

    Full Text Available High-latitude peatlands contain about one third of the world's soil organic carbon, most of which is derived from partly decomposed Sphagnum (peat moss plants. We conducted a meta-analysis based on a global dataset of Sphagnum growth measurements collected from published literature to investigate the effects of bioclimatic variables on Sphagnum growth. Analysis of variance and general linear models were used to relate Sphagnum magellanicum and S. fuscum growth rates to photosynthetically active radiation integrated over the growing season (PAR0 and a moisture index. We found that PAR0 was the main predictor of Sphagnum growth for the global dataset, and effective moisture was only correlated with moss growth at continental sites. The strong correlation between Sphagnum growth and PAR0 suggests the existence of a global pattern of growth, with slow rates under cool climate and short growing seasons, highlighting the important role of temperature and growing season length in explaining peatland biomass production. Large-scale patterns of cloudiness during the growing season might also limit moss growth. Although considerable uncertainty remains over the carbon balance of peatlands under a changing climate, our results suggest that increasing PAR0 as a result of global warming and lengthening growing seasons could promote Sphagnum growth. Assuming that production and decomposition have the same sensitivity to temperature, this enhanced growth could lead to greater peat-carbon sequestration, inducing a negative feedback to climate change.

  8. Glioblastoma Recurrence Patterns After Radiation Therapy With Regard to the Subventricular Zone

    Energy Technology Data Exchange (ETDEWEB)

    Adeberg, Sebastian, E-mail: Sebastian.adeberg@med.uni-heidelberg [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); König, Laila; Bostel, Tilman; Harrabi, Semi; Welzel, Thomas [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Debus, Jürgen [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Heidelberg Ion Therapy Center, Heidelberg (Germany); DKFZ Clinical Cooperation Unit Radiation Oncology, German Cancer Research Center Heidelberg (Germany); Combs, Stephanie E. [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Heidelberg Ion Therapy Center, Heidelberg (Germany)

    2014-11-15

    Purpose: We evaluated the influence of tumor location and tumor spread in primary glioblastoma (GBM), with respect to the subventricular zone (SVZ), on recurrence behavior, progression-free survival (PFS), and overall survival (OS). Methods and Materials: 607 patients (376 male and 231 female) with a median age of 61.3 years (range, 3.0-87.9 years) and primary GBM treated with radiation therapy (RT) from 2004 to 2012 at a single institution were included in this retrospective study. Preoperative images and follow-up examination results were assessed to evaluate tumor location. Tumors were classified according to the tumor location in relation to the SVZ. Results: The median PFS of the study population was 5.2 months (range, 1-91 months), and the median OS was 13.8 months (range, 1-102 months). Kaplan-Meier analysis showed that tumor location in close proximity to the SVZ was associated with a significant decline in PFS and OS (4.8 and 12.3 months, respectively; each P<.001). Furthermore, in cases where tumors were involved with the SVZ, distant cerebral progression (43.8%; P=.005) and multifocal progression (39.8%; P=.008) were more common. Interestingly, opening of the ventricle during the previous surgery showed no impact on PFS and OS. Conclusion: GBM in close proximity to the SVZ was associated with decreased survival and had a higher risk of multifocal or distant progression. Ventricle opening during surgery had no effect on survival rates.

  9. Patterns of Disease Recurrence Following Treatment of Oropharyngeal Cancer With Intensity Modulated Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Garden, Adam S., E-mail: agarden@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Dong, Lei [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Morrison, William H. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Stugis, Erich M. [Department of Head and Neck Surgery, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Department of Epidemiology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Glisson, Bonnie S. [Department of Thoracic/Head and Neck Medicine, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Frank, Steven J.; Beadle, Beth M.; Gunn, Gary B. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Schwartz, David L. [Department of Radiation Medicine, Long Island Jewish Medical Center, New Hyde Park, NY (United States); Kies, Merill S. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Department of Thoracic/Head and Neck Medicine, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Weber, Randal S. [Department of Head and Neck Surgery, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Ang, K. Kian; Rosenthal, David I. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States)

    2013-03-15

    Purpose: To report mature results of a large cohort of patients diagnosed with squamous cell carcinoma of the oropharynx who were treated with intensity modulated radiation therapy (IMRT). Methods and Materials: The database of patients irradiated at The University of Texas, M.D. Anderson Cancer Center was searched for patients diagnosed with oropharyngeal cancer and treated with IMRT between 2000 and 2007. A retrospective review of outcome data was performed. Results: The cohort consisted of 776 patients. One hundred fifty-nine patients (21%) were current smokers, 279 (36%) former smokers, and 337 (43%) never smokers. T and N categories and American Joint Committee on Cancer group stages were distributed as follows: T1/x, 288 (37%); T2, 288 (37%); T3, 113 (15%); T4, 87 (11%); N0, 88(12%); N1/x, 140 (18%); N2a, 101 (13%); N2b, 269 (35%); N2c, 122 (16%); and N3, 56 (7%); stage I, 18(2%); stage II, 40(5%); stage III, 150(19%); and stage IV, 568(74%). Seventy-one patients (10%) presented with nodes in level IV. Median follow-up was 54 months. The 5-year overall survival, locoregional control, and overall recurrence-free survival rates were 84%, 90%, and 82%, respectively. Primary site recurrence developed in 7% of patients, and neck recurrence with primary site control in 3%. We could only identify 12 patients (2%) who had locoregional recurrence outside the high-dose target volumes. Poorer survival rates were observed in current smokers, patients with larger primary (T) tumors and lower neck disease. Conclusions: Patients with oropharyngeal cancer treated with IMRT have excellent disease control. Locoregional recurrence was uncommon, and most often occurred in the high dose volumes. Parotid sparing was accomplished in nearly all patients without compromising tumor coverage.

  10. Revisiting radiation patterns in e{sup +}e{sup -} collisions

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, N.; Gieseke, S. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Theoretische Physik; Plaetzer, S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Skands, P. [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-02-15

    We propose four simple event-shape variables for semi-inclusive e{sup +}e{sup -}→4-jet events. The observables and cuts are designed to be especially sensitive to subleading aspects of the event structure, and allow to test the reliability of phenomenological QCD models in greater detail. Three of them, θ{sub 14}, θ{sup *}, and C{sup (1/5)}{sub 2}, focus on soft emissions off three-jet topologies with a small opening angle, for which coherence effects beyond the leading QCD dipole pattern are expected to be enhanced. A complementary variable, M{sup 2}{sub L}/M{sup 2}{sub H}, measures the ratio of the hemisphere masses in 4-jet events with a compressed scale hierarchy (Durham y{sub 23}∝y{sub 34}), for which subleading 1→3 splitting effects are expected to be enhanced. We consider several different parton-shower models, spanning both conventional and dipole/antenna ones, all tuned to the same e{sup +}e{sup -} reference data, and show that a measurement of the proposed observables would allow for additional significant discriminating power between the models.

  11. Dependence of AeroMACS Interference on Airport Radiation Pattern Characteristics

    Science.gov (United States)

    Wilson, Jeffrey D.

    2012-01-01

    AeroMACS (Aeronautical Mobile Airport Communications System), which is based upon the IEEE 802.16e mobile wireless standard, is expected to be implemented in the 5091 to 5150 MHz frequency band. As this band is also occupied by Mobile Satellite Service (MSS) feeder uplinks, AeroMACS must be designed to avoid interference with this incumbent service. The aspects of AeroMACS operation that present potential interference are under analysis in order to enable the definition of standards that assure that such interference will be avoided. In this study, the cumulative interference power distribution at low earth orbit from AeroMACS transmitters at the 497 major airports in the contiguous United States was simulated with the Visualyse Professional software. The dependence of the interference power on the number of antenna beams per airport, gain patterns, and beam direction orientations was simulated. As a function of these parameters, the simulation results are presented in terms of the limitations on transmitter power required to maintain the cumulative interference power under the established threshold.

  12. Global Characterization of Biomass-Burning Patterns using Satellite Measurements of Fire Radiative Energy

    Science.gov (United States)

    Ichoku, Charles; Giglio, Louis; Wooster, Martin J.; Remer, Lorraine A.

    2008-01-01

    Remote sensing is the most practical means of measuring energy release from large open-air biomass burning. Satellite measurement of fire radiative energy (FRE) release rate or power (FRP) enables distinction between fires of different strengths. Based on a 1-km resolution fire data acquired globally by the MODerate-resolution Imaging Spectro-radiometer (MODIS) sensor aboard the Terra and Aqua satellites from 2000 to 2006, instanteaneous FRP values ranged between 0.02 MW and 1866 MW, with global daily means ranging between 20 and 40 MW. Regionally, at the Aqua-MODIS afternoon overpass, the mean FRP values for Alaska, Western US, Western Australia, Quebec and the rest of Canada are significantly higher than these global means, with Quebec having the overall highest value of 85 MW. Analysis of regional mean FRP per unit area of land (FRP flux) shows that a peak fire season in certain regions, fires can be responsible for up to 0.2 W/m(sup 2) at peak time of day. Zambia has the highest regional monthly mean FRP flux of approximately 0.045 W/m(sup 2) at peak time of day and season, while the Middle East has the lowest value of approximately 0.0005 W/m(sup 2). A simple scheme based on FRP has been devised to classify fires into five categories, to facilitate fire rating by strength, similar to earthquakes and hurricanes. The scheme uses MODIS measurements of FRP at 1-km resolution as follows: catagory 1 (less than 100 MW), category 2 (100 to less than 500 MW), category 3 (500 to less than 1000 MW), category 4 (1000 to less than 1500 MW), catagory 5 (greater than or equal to 1500 MW). In most regions of the world, over 90% of fires fall into category 1, while only less than 1% fall into each of categories 3 to 5, although these proportions may differ significantly from day to day and by season. The frequency of occurence of the larger fires is region specific, and could not be explained by ecosystem type alone. Time-series analysis of the propertions of higher category

  13. Simulation study of transverse optical klystron radiation

    Institute of Scientific and Technical Information of China (English)

    XuHong-Liang; DiaoCao-Zheng; 等

    1997-01-01

    The radiation from a transverse optical klystron(TOK) is calculated by far field approximation and numerical integration,in which the effects of electron-beam emittance and energy spread are considered.Accurate electron-beam profiles have been experimentally determined and modeled by the Monte Carlo method.The calculated spectra illustrate the emittance of Hefei storage ring imposes on the spontaneous radiation of TOK.

  14. 非规则桥梁近、远场地震易损性对比分析%Near and far-field seismic fragility comparative analysis of irregular bridge

    Institute of Scientific and Technical Information of China (English)

    董俊; 单德山; 张二华; 马腾

    2016-01-01

    为研究高墩大跨非规则桥梁的近、远场地震易损性,建立了典型非规则公路连续刚构桥的理论地震易损性模型.考虑近、远场地震动和桥梁结构参数的不确定性,抽样并生成桥梁近、远场地震易损性分析的模型样本库,利用OpenSees软件对模型样本库进行非线性动力时程分析,获得结构动力响应.而后在确定桥梁各易损构件损伤指标的基础上,采用概率地震需求分析方法建立了桥梁各构件近、远场地震易损性曲线并进行对比分析.分析结果表明:非规则桥梁结构的易损性情况与地震动频谱特性、结构非规则性密切相关,各构件近场地震动损伤概率明显高于远场.将地震动按断层距分组进行桥梁地震易损性分析是必要的.获得的易损性曲线可用于评估非规则桥梁的抗震性能,并为震后桥梁损伤评估提供依据.%In order to carry out the near and far-field seismic vulnerability, the seismic vulnerability model of a certain typical irregular highway continuous rigid frame bridge of China was created. Considering the uncertainty of near and far-field earthquake and bridge parameters, by adopting sampling method, the model sample database was generated to carry out bridge seismic vulnerability analysis. In order to obtain the structural near and far-field dynamic response respectively, every model in the database was calculated by using nonlinear time history analysis by using the software such as OpenSees. And the pier and bearing damage index were obtained. Then based on the above studied results, and then the near and far-field fragility curves of bridge dangerous members were obtained by using the probabilistic seismic demand analysis method and then a comparative study analysis for near and far-field seismic vulnerability for the structural damage state was determined. The results showed that, the vulnerability condition of the bridge component was closely related to

  15. Patterns of Radiation Therapy Practice for Patients Treated for Intact Cervical Cancer in 2005 to 2007: A Quality Research in Radiation Oncology Study

    Energy Technology Data Exchange (ETDEWEB)

    Eifel, Patricia J., E-mail: peifel@mdanderson.org [Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Ho, Alex; Khalid, Najma [American College of Radiology Clinical Research Center, Philadelphia, Pennsylvania (United States); Erickson, Beth [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin (United States); Owen, Jean [American College of Radiology Clinical Research Center, Philadelphia, Pennsylvania (United States)

    2014-06-01

    Purpose: To assess practice patterns and compliance with clinical performance measures for radiation therapy (RT) for patients with intact carcinoma of the cervix. Methods and Materials: Trained research associates reviewed the records of 261 randomly selected patients who received RT for cervix carcinoma between 2005 and 2007 from 45 facilities randomly selected after stratification by practice type. National estimates of patient and treatment characteristics were calculated from survey data using SUDAAN statistical software. Results: From the survey data, we estimated that only 8% of US facilities treated on average more than 3 eligible patients per year. No small or medium nonacademic facilities in the survey treated more than 3 eligible patients per year. Approximately 65.5% of patients began treatment in a facility that treated 3 or fewer eligible patients per year. Although 87.5% of patients had brachytherapy as part of their treatment, the proportion treated with external beam RT only was about double that estimated from the 1996 to 1999 survey. The use of high-dose-rate brachytherapy sharply increased, particularly in small nonacademic facilities. Overall, patients treated in nonacademic facilities were more likely to have incomplete or protracted treatment; 43% of patients treated in small nonacademic facilities did not have treatment completed within 10 weeks. Also, patients treated in facilities that treated 3 or fewer eligible patients per year were significantly less likely to receive concurrent chemotherapy than were patients treated in other facilities. Conclusion: Survey results indicate a disturbingly high rate of noncompliance with established criteria for high-quality care of patients with cervical cancer. Noncompliance rates are particularly high in nonacademic facilities, especially those that treat relatively few patients with intact cervical cancer.

  16. Analytical simulation of the far-field jet noise and the unsteady jet flow-field by a model of periodic shedding of vortex ring from the jet exit

    Science.gov (United States)

    Liu, C. H.

    1975-01-01

    The construction of a theoretical flow field due to shedding of vortex rings, the identification of the controlling parameters, and the determination of whether the theoretical model successfully simulated the unsteady pressure field near jet (and consequently the far field noise) was studied. The basic parameters contained in the analytic solutions were the epoch at which a vortex ring was shed near the jet exit and the eddy viscosity coefficient. These parameters were identified from the experimental data for the real-time pressure and from the spread of the mixing layer of the jet. Results of the theoretical analysis show good qualitative agreement with the experimental data.

  17. Far-Field Deformation Resulting from Rheologic Differences Interacting with Tectonic Stresses: An Example from the Pacific/Australian Plate Boundary in Southern New Zealand

    Directory of Open Access Journals (Sweden)

    Phaedra Upton

    2014-07-01

    Full Text Available The Miocene in Southern New Zealand was dominated by strike-slip tectonics. Stratigraphic evidence from this time attests to two zones of subsidence in the south: (a a middle Cenozoic pull-apart basin and (b a regionally extensive subsiding lake complex, which developed east and distal to the developing plate boundary structure. The lake overlay a block of crust with a significantly weak mid-crustal section and we pose the question: can rheological transitions at an angle to a plate boundary produce distal subsidence and/or uplift? We use stratigraphic, structural and geophysical observations from Southern New Zealand to constrain three-dimensional numerical models for a variety of boundary conditions and rheological scenarios. We show that coincident subsidence and uplift can result from purely strike-slip boundary conditions interacting with a transition from strong to weak to strong mid-crustal rheology. The resulting pattern of vertical displacement is a function of the symmetry or asymmetry of the boundary conditions and the extent and orientation of the rheological transitions. For the Southern New Zealand case study, subsidence rates of ~0.1 mm/yr are predicted for a relative plate motion of 25 mm/yr, leading to ~500 m of subsidence over a 5 Ma time period, comparable to the thickness of preserved lacustrine sediments.

  18. Radiation Characteristics of Guided and Leaky modes for a Plasma Column Antenna

    Directory of Open Access Journals (Sweden)

    Bo Yin

    2013-07-01

    Full Text Available  A substantial problem for the radiation of a plasma column antenna is investigated. By means of the study on electromagnetic (EM waves propagating along the plasma column and acting with plasma, it is found that a plasma column can radiate the EM energy when it works as two kinds of operation modes. The first one is a guided mode which leads to a surface current radiation, and its operation condition is obtained by determining the relation of plasma frequency and signal frequency. The second one is a leaky mode which causes a leaky wave radiation, and its operation condition is presented by analyzing normalized complex propagation constant. With further dealing with the leaky mode, its far field is got by applying the Schelkunoff’s equivalence principle on the surface of the plasma column. Radiation patterns of two kinds of modes are presented in their respective operation frequency bands, and reveal the radiation properties of the plasma antenna. The presented results are very helpful for further investigation in the design and application of plasma column antenna

  19. Distribution patterns of lentic-breeding amphibians in relation to ultraviolet radiation exposure in western North America

    Science.gov (United States)

    Adams, Michael J.; Hossack, B.R.; Knapp, R.A.; Corn, P.S.; Diamond, S.A.; Trenham, P.C.; Fagre, D.B.

    2005-01-01

    An increase in ultraviolet-B (UV-B) radiation has been posited to be a potential factor in the decline of some amphibian population. This hypothesis has received support from laboratory and field experiments showing that current levels of UV-B can cause embryo mortality in some species, but little research has addressed whether UV-B is influencing the distribution of amphibian populations. We compared patterns of amphibian presence to site-specific estimates of UV-B dose at 683 ponds and lakes in Glacier, Olympic, and Sequoia–Kings Canyon National Parks. All three parks are located in western North America, a region with a concentration of documented amphibian declines. Site-specific daily UV-B dose was estimated using modeled and field-collected data to incorporate the effects of elevation, landscape, and water-column dissolved organic carbon. Of the eight species we examined (Ambystoma gracile, Ambystoma macrodactylum, Bufo boreas, Pseudacris regilla, Rana cascadae, Rana leuteiventris, Rana muscosa, Taricha granulosa), two species (T. granulosa and A. macrodactylum) had quadratic relationships with UV-B that could have resulted from negative UV-B effects. Both species were most likely to occur at moderate UV-B levels. Ambystoma macrodactylum showed this pattern only in Glacier National Park. Occurrence of A. macrodactylum increased as UV-B increased in Olympic National Park despite UV-B levels similar to those recorded in Glacier. We also found marginal support for a negative association with UV-B for P. regilla in one of the two parks where it occurred. We did not find evidence of a negative UV-B effect for any other species. Much more work is still needed to determine whether UV-B, either alone or in concert with other factors, is causing widespread population losses in amphibians.

  20. Non-LTR R2 element evolutionary patterns: phylogenetic incongruences, rapid radiation and the maintenance of multiple lineages.

    Directory of Open Access Journals (Sweden)

    Andrea Luchetti

    Full Text Available Retrotransposons of the R2 superclade specifically insert within the 28S ribosomal gene. They have been isolated from a variety of metazoan genomes and were found vertically inherited even if their phylogeny does not always agree with that of the host species. This was explained with the diversification/extinction of paralogous lineages, being proved the absence of horizontal transfer. We here analyze the widest available collection of R2 sequences, either newly isolated from recently sequenced genomes or drawn from public databases, in a phylogenetic framework. Results are congruent with previous analyses, but new important issues emerge. First, the N-terminal end of the R2-B clade protein, so far unknown, presents a new zinc fingers configuration. Second, the phylogenetic pattern is consistent with an ancient, rapid radiation of R2 lineages: being the estimated time of R2 origin (850-600 Million years ago placed just before the metazoan Cambrian explosion, the wide element diversity and the incongruence with the host phylogeny could be attributable to the sudden expansion of available niches represented by host's 28S ribosomal genes. Finally, we detect instances of coexisting multiple R2 lineages showing a non-random phylogenetic pattern, strongly similar to that of the "library" model known for tandem repeats: a collection of R2s were present in the ancestral genome and then differentially activated/repressed in the derived species. Models for activation/repression as well as mechanisms for sequence maintenance are also discussed within this framework.

  1. Far-Field Acoustic Power Level and Performance Analyses of F31/A31 Open Rotor Model at Simulated Scaled Takeoff, Nominal Takeoff, and Approach Conditions: Technical Report I

    Science.gov (United States)

    Sree, Dave

    2015-01-01

    Far-field acoustic power level and performance analyses of open rotor model F31/A31 have been performed to determine its noise characteristics at simulated scaled takeoff, nominal takeoff, and approach flight conditions. The nonproprietary parts of the data obtained from experiments in 9- by 15-Foot Low-Speed Wind Tunnel (9?15 LSWT) tests were provided by NASA Glenn Research Center to perform the analyses. The tone and broadband noise components have been separated from raw test data by using a new data analysis tool. Results in terms of sound pressure levels, acoustic power levels, and their variations with rotor speed, angle of attack, thrust, and input shaft power have been presented and discussed. The effect of an upstream pylon on the noise levels of the model has been addressed. Empirical equations relating model's acoustic power level, thrust, and input shaft power have been developed. The far-field acoustic efficiency of the model is also determined for various simulated flight conditions. It is intended that the results presented in this work will serve as a database for comparison and improvement of other open rotor blade designs and also for validating open rotor noise prediction codes.

  2. Wakefield radiation from the open end of an internally coated metallic tube

    Directory of Open Access Journals (Sweden)

    M. Ivanyan

    2014-07-01

    Full Text Available In this paper the problem of radiation from the open end of a semi-infinite circular metallic waveguide with perfectly conducting walls and a thin internal low-conducting metal coating is considered. Electromagnetic fields are generated by the ultrarelativistic point charge moving along the axis of the waveguide. The far fields of radiation are obtained using the near-field to far-field recovery technique. The technique is extended for the nonmonochromatic waves. It is shown that the radiation has a narrow-band and narrow-directional character.

  3. Computation of antenna pattern correlation and MIMO performance by means of surface current distribution and spherical wave theory

    Directory of Open Access Journals (Sweden)

    O. Klemp

    2006-01-01

    Full Text Available In order to satisfy the stringent demand for an accurate prediction of MIMO channel capacity and diversity performance in wireless communications, more effective and suitable models that account for real antenna radiation behavior have to be taken into account. One of the main challenges is the accurate modeling of antenna correlation that is directly related to the amount of channel capacity or diversity gain which might be achieved in multi element antenna configurations. Therefore spherical wave theory in electromagnetics is a well known technique to express antenna far fields by means of a compact field expansion with a reduced number of unknowns that was recently applied to derive an analytical approach in the computation of antenna pattern correlation. In this paper we present a novel and efficient computational technique to determine antenna pattern correlation based on the evaluation of the surface current distribution by means of a spherical mode expansion.

  4. Coupling between plate vibration and acoustic radiation

    Science.gov (United States)

    Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

    1993-01-01

    A detailed numerical investigation of the coupling between the vibration of a flexible plate and the acoustic radiation is performed. The nonlinear Euler equations are used to describe the acoustic fluid while the nonlinear plate equation is used to describe the plate vibration. Linear, nonlinear, and quasi-periodic or chaotic vibrations and the resultant acoustic radiation are analyzed. We find that for the linear plate response, acoustic coupling is negligible. However, for the nonlinear and chaotic responses, acoustic coupling has a significant effect on the vibration level as the loading increases. The radiated pressure from a plate undergoing nonlinear or chaotic vibrations is found to propagate nonlinearly into the far field. However, the nonlinearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance.

  5. SU-E-J-67: Evaluation of Breathing Patterns for Respiratory-Gated Radiation Therapy Using Respiration Regularity Index

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, K; Lee, M; Kang, S; Yoon, J; Park, S; Hwang, T; Kim, H; Kim, K; Han, T; Bae, H [Hallym University College of Medicine, Anyang (Korea, Republic of)

    2014-06-01

    Purpose: Despite the importance of accurately estimating the respiration regularity of a patient in motion compensation treatment, an effective and simply applicable method has rarely been reported. The authors propose a simple respiration regularity index based on parameters derived from a correspondingly simplified respiration model. Methods: In order to simplify a patient's breathing pattern while preserving the data's intrinsic properties, we defined a respiration model as a power of cosine form with a baseline drift. According to this respiration formula, breathing-pattern fluctuation could be explained using four factors: sample standard deviation of respiration period, sample standard deviation of amplitude and the results of simple regression of the baseline drift (slope and standard deviation of residuals of a respiration signal. Overall irregularity (δ) was defined as a Euclidean norm of newly derived variable using principal component analysis (PCA) for the four fluctuation parameters. Finally, the proposed respiration regularity index was defined as ρ=ln(1+(1/ δ))/2, a higher ρ indicating a more regular breathing pattern. Subsequently, we applied it to simulated and clinical respiration signals from real-time position management (RPM; Varian Medical Systems, Palo Alto, CA) and investigated respiration regularity. Moreover, correlations between the regularity of the first session and the remaining fractions were investigated using Pearson's correlation coefficient. Results: The respiration regularity was determined based on ρ; patients with ρ<0.3 showed worse regularity than the others, whereas ρ>0.7 was suitable for respiratory-gated radiation therapy (RGRT). Fluctuations in breathing cycle and amplitude were especially determinative of ρ. If the respiration regularity of a patient's first session was known, it could be estimated through subsequent sessions. Conclusions: Respiration regularity could be objectively determined

  6. Properties of undulator radiation

    Energy Technology Data Exchange (ETDEWEB)

    Veal, B.W.

    1985-11-01

    Properties of the radiation emitted by a plane sinusoidal undulator are calculated in the far field approximation. Software has been developed to calculate the spectral distribution and polarization of the radiated intensity I(E) at a point on (or integrated over) a cross sectional observation plane of the photon beam. Spatial distribution of monochromatic radiation and power density contours are also calculated. Spectral broadening caused by an electron beam of finite spatial distribution is considered. Dispersive properties of the photon beam, including the dependence on deflection parameter, are analyzed. It is shown that reasonably constant intensity distribution I(E) can be obtained by properly shaping the beam acceptance aperture. 5 refs., 11 figs.

  7. Signal-to-noise and radiation exposure considerations in conventional and diffraction x-ray microscopy.

    Science.gov (United States)

    Huang, Xiaojing; Miao, Huijie; Steinbrener, Jan; Nelson, Johanna; Shapiro, David; Stewart, Andrew; Turner, Joshua; Jacobsen, Chris

    2009-08-03

    Using a signal-to-noise ratio estimation based on correlations between multiple simulated images, we compare the dose efficiency of two soft x-ray imaging systems: incoherent brightfield imaging using zone plate optics in a transmission x-ray microscope (TXM), and x-ray diffraction microscopy (XDM) where an image is reconstructed from the far-field coherent diffraction pattern. In XDM one must computationally phase weak diffraction signals; in TXM one suffers signal losses due to the finite numerical aperture and efficiency of the optics. In simulations with objects representing isolated cells such as yeast, we find that XDM has the potential for delivering equivalent resolution images using fewer photons. This can be an important advantage for studying radiation-sensitive biological and soft matter specimens.

  8. Research on Radiation Characteristic of Plasma Antenna through FDTD Method

    Directory of Open Access Journals (Sweden)

    Jianming Zhou

    2014-01-01

    Full Text Available The radiation characteristic of plasma antenna is investigated by using the finite-difference time-domain (FDTD approach in this paper. Through using FDTD method, we study the propagation of electromagnetic wave in free space in stretched coordinate. And the iterative equations of Maxwell equation are derived. In order to validate the correctness of this method, we simulate the process of electromagnetic wave propagating in free space. Results show that electromagnetic wave spreads out around the signal source and can be absorbed by the perfectly matched layer (PML. Otherwise, we study the propagation of electromagnetic wave in plasma by using the Boltzmann-Maxwell theory. In order to verify this theory, the whole process of electromagnetic wave propagating in plasma under one-dimension case is simulated. Results show that Boltzmann-Maxwell theory can be used to explain the phenomenon of electromagnetic wave propagating in plasma. Finally, the two-dimensional simulation model of plasma antenna is established under the cylindrical coordinate. And the near-field and far-field radiation pattern of plasma antenna are obtained. The experiments show that the variation of electron density can introduce the change of radiation characteristic.

  9. Outcomes and Patterns of Failure for Grade 2 Meningioma Treated With Reduced-Margin Intensity Modulated Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Press, Robert H. [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Prabhu, Roshan S., E-mail: roshansprabhu@gmail.com [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Appin, Christina L.; Brat, Daniel J. [Department of Pathology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Shu, Hui-Kuo G. [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Hadjipanayis, Constantinos; Olson, Jeffrey J.; Oyesiku, Nelson M. [Department of Neurosurgery, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Curran, Walter J.; Crocker, Ian [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States)

    2014-04-01

    Purpose: The purpose of this study was to evaluate intracranial control and patterns of local recurrence (LR) for grade 2 meningiomas treated with intensity modulated radiation therapy (IMRT) with limited total margin expansions of ≤1 cm. Methods and Materials: We reviewed records of patients with a neuropathological diagnosis of grade 2 meningioma who underwent IMRT at our institution between 2002 and 2012. Actuarial rates were determined by the Kaplan-Meier method from the end of RT. LR was defined as in-field if ≥90% of the recurrence was within the prescription isodose, out-of-field (marginal) if ≥90% was outside of the prescription isodose, and both if neither criterion was met. Results: Between 2002 and 2012, a total of 54 consecutive patients underwent IMRT for grade 2 meningioma. Eight of these patients had total initial margins >1 cm and were excluded, leaving 46 patients for analysis. The median imaging follow-up period was 26.2 months (range, 7-107 months). The median dose for fractionated IMRT was 59.4 Gy (range, 49.2-61.2 Gy). Median clinical target volume (CTV), planning target volume (PTV), and total margin expansion were 0.5 cm, 0.3 cm, and 0.8 cm, respectively. LR occurred in 8 patients (17%), with 2-year and 3-year actuarial local control (LC) of 92% and 74%, respectively. Six of 8 patients (85%) had a known pattern of failure. Five patients (83%) had in-field LR; no patients had marginal LR; and 1 patient (17%) had both. Conclusions: The use of IMRT to treat grade 2 meningiomas with total initial margins (CTV + PTV) ≤1 cm did not appear to compromise outcomes or increase marginal failures compared with other modern retrospective series. Of the 46 patients who had margins ≤1 cm, none experienced marginal failure only. These results demonstrate efficacy and low risk of marginal failure after IMRT treatment of grade 2 meningiomas with reduced margins, warranting study within a prospective clinical trial.

  10. 基于光导微探针的近场/远场可扫描太赫兹光谱技术∗%Near-field and far-field scanning terahertz sp ectroscopy based on photo conductive microprob e

    Institute of Scientific and Technical Information of China (English)

    许悦红; 张伟力; 张学迁; 王球; 田震; 谷建强; 欧阳春梅; 路鑫超; 张文涛; 韩家广

    2016-01-01

    Recently, terahertz radiation has been a branch of cutting-edge science and technology involving many fields such as public security, military defense and national economy. In the past, far-field measurements were widely carried out based on terahertz time-domain spectroscopy. But the spatial resolution is limited by far-field diffraction effect. In order to break diffraction limit and gain sub-wavelength spatial resolution in terahertz frequency region, a series of near-field detection methods came into being, such as confocal microscopy, using an aperture, guided mode, scattering, direct detection in the near-field, etc. Each method has its own advantages and disadvantages. Using the photoconductive-antenna tip is one of the direct detection methods and it delivers the possibility of near-field measurements of terahertz waves. In this method, the photoconductive-antenna tip is a tapered photoconductive tip probe. So it can be close enough to the sample surface and receive the near-field signal on the basis of principle of photoconductivity. In this way, high spatial resolution can be gained. In this article, we introduce our recent progress of near-field and far- field scanning terahertz spectroscopy system with photoconductive-antenna in detail. Firstly, we analyze and summarize the near-field detection methods that have been developed in these years. And then, using the femtosecond laser whose center wavelength is 800 nm and the photoconductive-antenna tip detector coupled with fiber, we construct fiber near-field/far-field scanning terahertz spectroscopy (N/F-STS). The frequency bandwidth is in a range from 0.2 THz to 1.5 THz and the terahertz spot is circular and uniform indicated by performance test. Also the amplitude and phase of the terahertz field are recorded simultaneously. It has the ability to perform three-dimension scan in various experiment conditions conveniently. Finally, we introduce the real applications in our laboratory. N/F-STS can be used

  11. Characterization of Personal Privacy Devices (PPD) radiation pattern impact on the ground and airborne segments of the local area augmentation system (LAAS) at GPS L1 frequency

    Science.gov (United States)

    Alkhateeb, Abualkair M. Khair

    Personal Privacy Devices (PPDs) are radio-frequency transmitters that intentionally transmit in a frequency band used by other devices for the intent purpose of denying service to those devices. These devices have shown the potential to interfere with the ground and air sub-systems of the Local Area Augmentation Systems (LAAS), a GPS-based navigation aids at commercial airports. The Federal Aviation Administration (FAA) is concerned by the potential impact of these devices to GPS navigation aids at airports and has commenced an activity to determine the severity of this threat. In support of this situation, the research in this dissertation has been conducted under (FAA) Cooperative Agreement 2011-G-012, to investigate the impact of these devices on the LAAS. In order to investigate the impact of PPDs Radio Frequency Interference (RFI) on the ground and air sub-systems of the LAAS, the work presented in phase one of this research is intended to characterize the vehicle's impact on the PPD's Effective Isotropic Radiated Power (EIRP). A study was conceived in this research to characterize PPD performance by examining the on-vehicle radiation patterns as a function of vehicle type, jammer type, jammer location inside a vehicle and jammer orientation at each location. Phase two was to characterize the GPS Radiation Pattern on Multipath Limiting Antenna. MLA has to meet stringent requirements for acceptable signal detection and multipath rejection. The ARL-2100 is the most recent MLA antenna proposed to be used in the LAAS ground segment. The ground-based antenna's radiation pattern was modeled. This was achieved via (HFSS) a commercial-off the shelf CAD-based modeling code with a full-wave electromagnetic software simulation package that uses the Finite Element Analysis. Phase three of this work has been conducted to study the characteristics of the GPS Radiation Pattern on Commercial Aircraft. The airborne GPS antenna was modeled and the resulting radiation pattern on

  12. 远场超分辨随机光重建显微镜(STORM)研究进展%Progress in far-field super-resolution stochastic optical reconstruction microscopy(STORM)

    Institute of Scientific and Technical Information of China (English)

    王成; 马俊领; 魏勋斌

    2011-01-01

    Understanding intracellular molecule-scale characteristic of dynamics and structures is urgently demanded to solve issues in today's life science. In order to solve this problem, a far field optical imaging obtained nanometer or sub-nanometer scale 3D resolution will be demanded. The far-field fluorescence microscopy, which broken diffraction barrier, Stochastic Optical Restructure Microscopy (STORM) is introduced. The STORM can be achieved resolution of 20 nm laterally and 50 nm axially. In theory, the STORM can be achieved single molecule location precision. Imaging foundational principle, progress of 3D and multi-color imaging, recently faced challenge as well as the direction of development about the STORM is talked in detailed.%了解细胞内分子尺度的动态和结构的特征是生命科学迫切需要解决的问题,要求远场光学成像要求纳米或亚纳米量级的空间分辨率.介绍了一种实现打破衍射极限的远场荧光显微成像技术--随机光重建显微术(STORM),其分辨率可以达到横向分辨率20 nm,轴向分辨率50 nm,理论上这种方法的空间分辨率可以达到单分子定位的精度.具体介绍了其成像的基本原理,在三维、多色成像方面的进展,和目前面临的问题及今后的发展方向.

  13. A comparative study of discrete fracture network and equivalent continuum models for simulating flow and transport in the far field of a hypothetical nuclear waste repository in crystalline host rock

    Science.gov (United States)

    Hadgu, Teklu; Karra, Satish; Kalinina, Elena; Makedonska, Nataliia; Hyman, Jeffrey D.; Klise, Katherine; Viswanathan, Hari S.; Wang, Yifeng

    2017-10-01

    One of the major challenges of simulating flow and transport in the far field of a geologic repository in crystalline host rock is related to reproducing the properties of the fracture network over the large volume of rock with sparse fracture characterization data. Various approaches have been developed to simulate flow and transport through the fractured rock. The approaches can be broadly divided into Discrete Fracture Network (DFN) and Equivalent Continuum Model (ECM). The DFN explicitly represents individual fractures, while the ECM uses fracture properties to determine equivalent continuum parameters. We compare DFN and ECM in terms of upscaled observed transport properties through generic fracture networks. The major effort was directed on making the DFN and ECM approaches similar in their conceptual representations. This allows for separating differences related to the interpretation of the test conditions and parameters from the differences between the DFN and ECM approaches. The two models are compared using a benchmark test problem that is constructed to represent the far field (1 × 1 × 1 km3) of a hypothetical repository in fractured crystalline rock. The test problem setting uses generic fracture properties that can be expected in crystalline rocks. The models are compared in terms of the: 1) effective permeability of the domain, and 2) nonreactive solute breakthrough curves through the domain. The principal differences between the models are mesh size, network connectivity, matrix diffusion and anisotropy. We demonstrate how these differences affect the flow and transport. We identify the factors that should be taken in consideration when selecting an approach most suitable for the site-specific conditions.

  14. Frequency and distance changes in the apparent P-wave radiation pattern: effects of seismic wave scattering in the crust inferred from dense seismic observations and numerical simulations

    Science.gov (United States)

    Kobayashi, Manabu; Takemura, Shunsuke; Yoshimoto, Kazuo

    2015-09-01

    Frequency and distance changes in the apparent P-wave radiation pattern (0.75-12 Hz) are investigated using velocity seismograms of shallow strike-slip earthquakes occurring in Chugoku region, southwestern Japan. Data from a dense seismic monitoring network revealed that the four-lobe apparent P-wave radiation pattern was gradually distorted with increasing frequency and propagation distance. Observed features suggest that seismic wave scattering due to small-scale velocity heterogeneity in the crust may be a major cause of this distortion. The effects of seismic wave scattering on apparent P-wave radiation pattern were investigated via 3-D finite difference simulation of seismic wave propagation. Our simulations demonstrated that the scattering of seismic waves modified the apparent P-wave radiation pattern from the original four-lobe shape, and that the small-scale velocity heterogeneity, characterized by the von Kármán-type power spectral density function with correlation distance of 1 km, root-mean-square value of 0.03 and decay rate parameter of 0.5, might be adequate for modelling crustal heterogeneity in the target region. It was also found that the scattering attenuation of P wave expected from this heterogeneity is significantly smaller than the apparent P-wave attenuation and S-wave scattering attenuation reported by Multiple Lapse Time Window Analysis of previous studies in Japan. These results might imply that scattering attenuation is not the dominant mechanism of P-wave attenuation in the crust of Chugoku region.

  15. Potential solar radiation pattern in relation to the monthly distribution of giant pandas in Foping Nature Reserve, China

    NARCIS (Netherlands)

    Liu, X.; Cheng, X.; Skidmore, A.K.

    2011-01-01

    Solar radiation is an important parameter in ecological process modeling, hydrological modeling and bio-physical modeling. However, models focusing on solar radiation in relation to giant panda habitat and seasonal distribution are limited. The research aims to form spatial models of 12 month solar

  16. Potential solar radiation pattern in relation to the monthly distribution of giant pandas in Foping Nature Reserve, China

    NARCIS (Netherlands)

    Liu, X.; Cheng, X.; Skidmore, A.K.

    2011-01-01

    Solar radiation is an important parameter in ecological process modeling, hydrological modeling and bio-physical modeling. However, models focusing on solar radiation in relation to giant panda habitat and seasonal distribution are limited. The research aims to form spatial models of 12 month solar

  17. ANALYSIS OF THE FAR - FIELD PATTERN OF AN EXTENDED HEMISPHERICAL LENS/OBJECTIVE LENS MMW ANTENNA SYSTEM%毫米波扩展半球透镜/物镜天线系统辐射特性分析

    Institute of Scientific and Technical Information of China (English)

    窦文斌; 曾刚; 孙忠良

    1998-01-01

    采用射线追踪和场积分的方法分析了扩展半球透镜/物镜天线系统的辐射特性,给出了计算结果,表明该系统具有良好的辐射特性.通过改变扩展半球透镜的扩展长度,可以实现集成电路与各种准光系统的耦合,具有很强的实用价值.

  18. Current patterns of care for patients with extensive stage small cell lung cancer: Survey of US radiation oncologists on their recommendations regarding thoracic consolidation radiotherapy.

    Science.gov (United States)

    Mitin, Timur; Jain, Aditya; Degnin, Catherine; Chen, Yiyi; Henderson, Mark; Thomas, Charles R

    2016-10-01

    Current National Comprehensive Cancer Network (NCCN) guidelines recommend thoracic consolidation radiation therapy (TCRT) for patients with Extensive Stage Small Cell Lung Cancer (ES-SCLC) with response to systemic chemotherapy, based on two randomized clinical trials, which varied in patient selection and radiation therapy doses administered. The current pattern of practice among US radiation oncologists is unknown. We have surveyed practicing US radiation oncologist via a short online questionnaire. Respondents' characteristics and their self-rated knowledge base were analyzed for association with their treatment recommendations. We received 473 responses from practicing US radiation oncologists. Over half of respondents were practicing for over 10 years after completing residency training and 70% treated more than 10 lung cancer patients per year. 96% of respondents recommend TCRT for patients with ES-SCLC after systemic chemotherapy. Patient selection and radiation therapy doses vary greatly. High self-rated knowledge of individual clinical trials is associated with lower TCRT recommended doses. Patients treated at academic centers are less likely to receive TCRT than patients treated in private clinics (p=0.0101). Our analysis revealed that among the respondents, there was a very high adherence to current NCCN guidelines, which recommend TCRT for ES-SCLC patients with clinical response to systemic chemotherapy. The great variability in patient selection and radiation therapy doses is concerning and calls for future clinical trials to standardize treatment approaches and improve treatment outcomes among patients with ES-SCLC. Until such data exists and in light of poor long-term survival of patients with ES-SCLC, the shorter and less toxic regimen of 30Gy in 10 fractions should be used as the standard of care and the more aggressive regimens studied on clinical protocols. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Patterns of real-time occupational ultraviolet radiation exposure among a sample of outdoor workers in New Zealand.

    Science.gov (United States)

    Hammond, V; Reeder, A I; Gray, A

    2009-02-01

    Exposure to solar ultraviolet radiation (UVR) is an occupational health and safety issue for outdoor workers since excessive exposure is associated with negative health outcomes, including eye conditions and skin cancers. The objective of this research was to describe the pattern of UVR exposure experienced by outdoor workers from selected occupations in New Zealand in order to identify the impact of behaviour and work conditions on exposure. This paper reports on the occupational UVR exposure arm of a dual arm cross-sectional study that also examined workers' sun protection practices. For five consecutive working days in January-March 2007, electronic dosimeters were used to record the time-stamped UVR exposure of a sample of 77 outdoor workers from three occupations (building, horticulture and roading) in Central Otago, New Zealand. The geometric mean total daily UVR exposure (between 1100 and 1600 h) was 5.32 standard erythemal doses (SED; 95% reference range 0.28-19.97 SED). The geometric mean total daily UVR exposure as a percentage of the total daily ambient UVR was 20.5% (95% confidence interval 1.4-83.0%). Personal UVR exposure dipped between 1200 h and 1300 h--the same time that ambient UVR peaked--indicating the effect of shade seeking over the lunch period. Personal UVR exposure peaked between 1400 h and 1500 h, alongside decreasing ambient UVR levels, suggesting the influence of behavioural rather than climatic factors. The difference in workers' exposure between 1200 h and 1300 h, and 1400 h and 1500 h was statistically significant for both measured personal exposure (P < 0.005) and exposure calculated as a percentage of concurrent available ambient UVR (P < 0.005). All the workers in this study recorded mean daily UVR exposure in excess of the current recommended occupational exposure limits. Only a minority of workers sought shade during their lunch break; most remained in highly exposed conditions. There is no evidence that work tasks which involve

  20. Radiative heat transfer between metallic nanoparticles

    OpenAIRE

    Chapuis, Pierre-Olivier; Laroche, Marine; Volz, Sebastian; Greffet, Jean-Jacques

    2008-01-01

    International audience; In this letter, we study the radiative heat transfer between two nanoparticles in the near field and in the far field. We find that the heat transfer is dominated by the electric dipole-dipole interaction for dielectric particles and by the magnetic dipole-dipole interaction for metallic nanoparticles. We introduce polarizabilities formulas valid for arbitrary values of the skin depth. While the heat transfer mechanism is different for metallic and dielectric nanoparti...

  1. Suggestion of optimal radiation fields in rectal cancer patients after surgical resection for the development of the patterns of care study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Hoon; Park, Jin Hong; Kim, Dae Yong [College of Medicine, Ulsan Univ., Seoul (Korea, Republic of)] [and others

    2003-06-01

    To suggest the optimal radiation fields after a surgical resection based on a nationwide survey on the principles of radiotherapy for rectal cancer in the Korean Patterns of Care Study. A consensus committee, composed of radiation oncologists from 18 hospitals in Seoul Metropolitan area, developed a survey format to analyze radiation oncologist's treatment principles for rectal cancer after a surgical resection. The survey format included 19 questions on the principles of defining field margins, and was sent to the radiation oncologists in charge of gastrointestinal malignancies in all Korean hospitals (48 hospitals). Thirty three (69%) oncologists replied. On the basis of the replies and literature review, the committee developed guidelines for the optimal radiation fields for rectal cancer. The following guidelines were developed: superior border between the lower tip of the L5 vertebral body and upper sacroiliac joint; inferior border 2-3 cm distal to the anastomosis in patient whose sphincter was saved, and 2-3 cm distal to the perineal scar in patients whose anal sphincter was sacrificed; anterior margin at the posterior tip of the symphysis pubis or 2-3 cm anterior to the vertebral body, to include the internal iliac lymph node and posterior margin 1.5-2 cm posterior to the anterior surface of the sacrum, to include the presacral space with enough margin. Comparison with the guidelines, the replies on the superior margin coincided in 23 cases (70%), the inferior margin after sphincter saving surgery in 13 (39%), the inferior margin after abdominoperineal resection in 32 (97%), the lateral margin in 32 (97%), the posterior margins in 32 (97%) and the anterior margin in 16 (45%). These recommendations should be tailored to each patient according to the clinical characteristics such as tumor location, pathological and operative findings, for the optimal treatment. The adequacy of these guidelines should be proved by following the Korean Patterns of Care

  2. The influence of therapeutic radiation on the patterns of bone marrow in ovary-intact and ovariectomized mice.

    Directory of Open Access Journals (Sweden)

    Susanta K Hui

    Full Text Available BACKGROUND: The functional components of bone marrow (i.e., the hematopoietic and stromal populations and the adjacent bone have traditionally been evaluated incompletely as distinct entities rather than the integrated system. We perturbed this system in vivo using a medically relevant radiation model in the presence or absence of ovarian function to understand integrated tissue interaction. METHODOLOGY/PRINCIPAL FINDINGS: Ovary-intact and ovariectomized mice underwent either no radiation or single fractional 16 Gy radiation to the caudal skeleton (I ± R, OVX ± R. Marrow fat, hematopoietic cellularity, and cancellous bone volume fraction (BV/TV % were assessed. Ovariectomy alone did not significantly reduce marrow cellularity in non-irradiated mice (OVX-R vs. I-R, p = 0.8445 after 30 days; however it impaired the hematopoietic recovery of marrow following radiation exposure (OVX+R vs. I+R, p = 0.0092. The combination of radiation and OVX dramatically increases marrow fat compared to either factor alone (p = 0.0062. The synergistic effect was also apparent in the reduction of hematopoietic marrow cellularity (p = 0.0661; however it was absent in BV/TV% changes (p = 0.2520. The expected inverse relationship between marrow adiposity vs. hematopoietic cellularity and bone volume was observed. Interestingly compared with OVX mice, intact mice demonstrated double the reduction in hematopoietic cellularity and a tenfold greater degree of bone loss for a given unit of expansion in marrow fat. CONCLUSIONS/SIGNIFICANCE: Ovariectomy prior to delivery of a clinically-relevant focal radiation exposure in mice, exacerbated post-radiation adipose accumulation in the marrow space but blunted bone loss and hematopoietic suppression. In the normally coupled homeostatic relationship between the bone and marrow domains, OVX appears to alter feedback mechanisms. Confirmation of this non-linear phenomenon (presumably due to differential radiosensitivity and

  3. Restoring in-phase emissions from non-planar radiating elements using a transformation optics based lens

    Science.gov (United States)

    Yi, Jianjia; Burokur, Shah Nawaz; Piau, Gérard-Pascal; de Lustrac, André

    2015-07-01

    The broadband directive in-phase emission from an array of sources conformed cylindrically is numerically and experimentally reported. Such manipulation is achieved through the use of a lens designed by transformation optics concept. The all-dielectric lens prototype is realized through three-dimensional (3D) polyjet printing and presents a graded refractive index. A microstrip antenna array fabricated using standard lithography techniques and conformed on a cylindrical surface is used as TE-polarized wave launcher for the lens. To experimentally demonstrate the broadband focusing properties and in-phase directive emissions, both the far-field radiation patterns and the near-field distributions have been measured. Experimental measurements agreeing qualitatively with numerical simulations validate the proposed lens and open the way to inexpensive all-dielectric microwave lenses for beam forming and collimation.

  4. Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC Applied in Optimization of Radiation Pattern Control of Phased-Array Radars for Rocket Tracking Systems

    Directory of Open Access Journals (Sweden)

    Leonardo W. T. Silva

    2014-08-01

    Full Text Available In launching operations, Rocket Tracking Systems (RTS process the trajectory data obtained by radar sensors. In order to improve functionality and maintenance, radars can be upgraded by replacing antennas with parabolic reflectors (PRs with phased arrays (PAs. These arrays enable the electronic control of the radiation pattern by adjusting the signal supplied to each radiating element. However, in projects of phased array radars (PARs, the modeling of the problem is subject to various combinations of excitation signals producing a complex optimization problem. In this case, it is possible to calculate the problem solutions with optimization methods such as genetic algorithms (GAs. For this, the Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC method was developed to control the radiation pattern of PAs. The GA-MMC uses a reconfigurable algorithm with multiple objectives, differentiated coding and a new crossover genetic operator. This operator has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, GA-MMC was successful in more than 90% of the tests for each application, increased the fitness of the final population by more than 20% and reduced the premature convergence.

  5. Far-field divergence for Gaussian beam under annular aperture diffraction%圆环孔径衍射高斯光束远场发散角研究

    Institute of Scientific and Technical Information of China (English)

    王超; 董科研; 江伦; 安岩

    2015-01-01

    The simple approximated analytic expression for the far-field divergence angle of Gaussian beam diffracted by an annular aperture was derived based on the Fraunhofer diffraction theory and by the approximate of the diffraction integration kernel function. For diffraction aperture with different diameters and obscuration ratios (OR), the analytic expression was compared by strict Fraunhofer diffraction expression, and the far-field divergences solved by these two expressions were nearly identical. The error was no more than 2.7%. Compared with the traditional method of getting the beam divergence by numerical integration, the troublesome integral was avoided, but a relative high precision was kept through this approximated formula. The analytic formula was effective on condition that the Gaussian beam waist diameter was more than or equal to 3.5 times the obscuration diameter, and less than or equal to the aperture diameter. In an actual engineering application, especially the space laser communication optical antenna with the characteristics of large-aperture and small-OR, the establishing conditions generally are satisfied.%基于夫琅禾费衍射理论,通过对衍射积分的核函数进行近似,推导并得出了简洁的经圆环形孔径衍射的高斯光束远场发散角的近似解析式.在不同衍射孔径外径和不同遮拦比的条件下,将该解析式与严格的夫琅禾费衍射积分进行比较,发现二者求出的远场发散角接近一致,最大误差不超过2.7%.与传统数值积分求取光束发散角相比,该近似解析式在避免繁琐的积分运算同时保持了较高的精度.该解析式成立条件为高斯光束的束腰直径大于等于3.5倍中心遮拦直径,且小于等于孔径直径;在实际工程应用中,特别是具有大口径、小遮拦比特点的空间激光通信光学天线这一应用场景,该条件一般能够被满足.

  6. Eustatic and far-field tectonic control on the development of an intra-platform carbonate-shoal complex: upper tongue of the Tanglewood Member, Upper Ordovician Lexington Limestone, central Kentucky, U.S.A.

    Science.gov (United States)

    Koirala, Dibya Raj; Ettensohn, Frank R.; Clepper, Marta L.

    2016-11-01

    the thickest and coarsest parts of each sequence, and the shallowest depositional environments, coincide with basement fault blocks, which are known to have experienced uplift during earlier Lexington Limestone deposition. The occurrence of thick, coarse facies on the same blocks suggests that the blocks continued to experience uplift into shallow water, where tides and waves redistributed sediments during upper Tanglewood deposition. Although eustasy apparently controlled cyclicity, Taconian far-field forces generated by orogeny in the east seem to have influenced facies distribution in each cycle through reactivation of basement fault zones as synsedimentary growth faults. The example of the upper Tanglewood Member shows that tectonic far-field forces can exert important influences on the development of carbonate depositional environments, even in distal intracratonic settings like the Lexington Platform.

  7. Choosing Wisely? Patterns and Correlates of the Use of Hypofractionated Whole-Breast Radiation Therapy in the State of Michigan

    Energy Technology Data Exchange (ETDEWEB)

    Jagsi, Reshma, E-mail: rjagsi@med.umich.edu [University of Michigan, Ann Arbor, Michigan (United States); Griffith, Kent A. [University of Michigan, Ann Arbor, Michigan (United States); Heimburger, David [Munson Medical Center, Traverse City, Michigan (United States); Walker, Eleanor M. [Henry Ford Hospital, Detroit, Michigan (United States); Grills, Inga S. [Beaumont Health System, Royal Oak, Michigan (United States); Boike, Thomas [McLaren Northern Michigan, Petoskey, Michigan (United States); Feng, Mary; Moran, Jean M.; Hayman, James; Pierce, Lori J. [University of Michigan, Ann Arbor, Michigan (United States)

    2014-12-01

    Purpose: Given evidence from randomized trials that have established the non-inferiority of more convenient and less costly courses of hypofractionated radiotherapy to the whole breast in selected breast cancer patients who receive lumpectomy, we sought to investigate the use of hypofractionated radiation therapy and factors associated with its use in a consortium of radiation oncology practices in Michigan. We sought to determine the extent to which variation in use occurs at the physician or practice level versus the extent to which use reflects individualization based on potentially relevant patient characteristics (such as habitus, age, chemotherapy receipt, or laterality). Methods and Materials: We evaluated associations between receipt of hypofractionated radiation therapy and various patient, provider, and practice characteristics in a multilevel model. Results: Of 1477 patients who received lumpectomy and whole-breast radiation therapy and were registered by the Michigan Radiation Oncology Quality Consortium (MROQC) from October 2011 to December 2013, 913 had T1-2, N0 breast cancer. Of these 913, 283 (31%) received hypofractionated radiation therapy. Among the 13 practices, hypofractionated radiation therapy use ranged from 2% to 80%. On multilevel analysis, 51% of the variation in the rate of hypofractionation was attributable to the practice level, 21% to the provider level, and 28% to the patient level. On multivariable analysis, hypofractionation was more likely in patients who were older (odds ratio [OR] 2.16 for age ≥50 years, P=.007), less likely in those with larger body habitus (OR 0.52 if separation between tangent entry and exit ≥25 cm, P=.002), and more likely without chemotherapy receipt (OR 3.82, P<.001). Hypofractionation use was not higher in the last 6 months analyzed: 79 of 252 (31%) from June 2013 to December 2013 and 204 of 661 (31%) from October 2011 to May 2013 (P=.9). Conclusions: Hypofractionated regimens of whole

  8. Coherent regime and far-to-near-field transition for radiative heat transfer

    Science.gov (United States)

    Tsurimaki, Yoichiro; Chapuis, Pierre-Olivier; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao; Vaillon, Rodolphe

    2017-01-01

    Radiative heat transfer between two semi-infinite parallel media is analyzed in the transition zone between the near-field and the classical macroscopic, i.e. incoherent far-field, regimes of thermal radiation, first for model gray materials and then for real metallic (Al) and dielectric (SiC) materials. The presence of a minimum in the flux-distance curve is observed for the propagative component of the radiative heat transfer coefficient, and in some cases for the total coefficient, i.e. the sum of the propagative and evanescent components. At best this reduction can reach 15% below the far-field limit in the case of aluminum. The far-to-near-field regime taking place for the distance range between the near-field and the classical macroscopic regime involves a coherent far-field regime. One of its limits can be practically defined by the distance at which the incoherent far-field regime breaks down. This separation distance below which the standard theory of incoherent thermal radiation cannot be applied anymore is found to be larger than the usual estimate based on Wien's law and varies as a function of temperature. The aforementioned effects are due to coherence, which is present despite the broadband spectral nature of thermal radiation, and has a stronger impact for reflective materials.

  9. Optically Thin Metallic Films for High-radiative-efficiency Plasmonics

    CERN Document Server

    Yang, Yi; Hsu, Chia Wei; Miller, Owen D; Joannopoulos, John D; Soljačić, Marin

    2016-01-01

    Plasmonics enables deep-subwavelength concentration of light and has become important for fundamental studies as well as real-life applications. Two major existing platforms of plasmonics are metallic nanoparticles and metallic films. Metallic nanoparticles allow efficient coupling to far field radiation, yet their synthesis typically leads to poor material quality. Metallic films offer substantially higher quality materials, but their coupling to radiation is typically jeopardized due to the large momentum mismatch with free space. Here, we propose and theoretically investigate optically thin metallic films as an ideal platform for high-radiative-efficiency plasmonics. For far-field scattering, adding a thin high-quality metallic substrate enables a higher quality factor while maintaining the localization and tunability that the nanoparticle provides. For near-field spontaneous emission, a thin metallic substrate, of high quality or not, greatly improves the field overlap between the emitter environment and ...

  10. Interplay between radiation pressure force and scattered light intensity in the cooperative scattering by cold atoms

    CERN Document Server

    Bienaime, Tom; Chabe, Julien; Rouabah, Mohamed-Taha; Bellando, Louis; Courteille, Philippe W; Piovella, Nicola; Kaiser, Robin

    2013-01-01

    The interplay between the superradiant emission of a cloud of cold two-level atoms and the radiation pressure force is discussed. Using a microscopic model of coupled atomic dipoles driven by an external laser, the radiation field and the average radiation pressure force are derived. A relation between the far-field scattered intensity and the force is derived, using the optical theorem. Finally, the scaling of the sample scattering cross section with the parameters of the system is studied.

  11. Sponge budding is a spatiotemporal morphological patterning process: Insights from synchrotron radiation-based x-ray microtomography into the asexual reproduction of Tethya wilhelma

    Directory of Open Access Journals (Sweden)

    Nickel Michael

    2009-09-01

    Full Text Available Abstract Background Primary agametic-asexual reproduction mechanisms such as budding and fission are present in all non-bilaterian and many bilaterian animal taxa and are likely to be metazoan ground pattern characters. Cnidarians display highly organized and regulated budding processes. In contrast, budding in poriferans was thought to be less specific and related to the general ability of this group to reorganize their tissues. Here we test the hypothesis of morphological pattern formation during sponge budding. Results We investigated the budding process in Tethya wilhelma (Demospongiae by applying 3D morphometrics to high resolution synchrotron radiation-based x-ray microtomography (SR-μCT image data. We followed the morphogenesis of characteristic body structures and identified distinct morphological states which indeed reveal characteristic spatiotemporal morphological patterns in sponge bud development. We discovered the distribution of skeletal elements, canal system and sponge tissue to be based on a sequential series of distinct morphological states. Based on morphometric data we defined four typical bud stages. Once they have reached the final stage buds are released as fully functional juvenile sponges which are morphologically and functionally equivalent to adult specimens. Conclusion Our results demonstrate that budding in demosponges is considerably more highly organized and regulated than previously assumed. Morphological pattern formation in asexual reproduction with underlying genetic regulation seems to have evolved early in metazoans and was likely part of the developmental program of the last common ancestor of all Metazoa (LCAM.

  12. Multi-mutational model for cancer based on age-time patterns of radiation effects: 2. Biological aspects

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, M.L.; Pierce, P.A.

    1997-09-04

    Biological properties of relevance when modeling cancers induced in the atom bomb survivors include the wide distribution of the induced cancers across all organs, their biological indistinguishability from background cancers, their rates being proportional to background cancer rates, their rates steadily increasing over at least 50 years as the survivors age, and their radiation dose response being linear. We have successfully described this array of properties with a modified Armitage-Doll model using 5 to 6 somatic mutations, no intermediate growth, and the dose-related replacement of any one of these time-driven mutations by a radiation-induced mutation. Such a model is contrasted to prevailing models that use fewer mutations combined with intervening growth. While the rationale and effectiveness of our model is compelling for carcinogenesis in the atom bomb survivors, the lack of a promotional component may limit the generality of the model for other types of human carcinogenesis.

  13. Cosmic radiation and airline pilots. Exposure patterns of Norwegian SAS-pilots 1960 to 1994. Revised Version

    Energy Technology Data Exchange (ETDEWEB)

    Tveten, U

    1999-02-01

    The present report is a revised version of an earlier report (IFE/KR/E-96/008). The revision has been carried out since a completely new version of the computational tool has recently been released. All calculations have been redone. The work which is presented in this report is part of a Norwegian epidemiological project, carried out in cooperation between Institute for Energy Technology (IFE), the Norwegian Cancer Registry (NCR) and the Norwegian Radiation Protection Authority (NRPA). Originating from the Norwegian project, a number of similar projects have been started in a number of European countries. The present report lays the ground for estimation of individual exposure histories to cosmic radiation of pilots employed by the the Scandinavian Airlines System (SAS). The result presented in this report (radiation dose rates for the different types of aircraft in the different years) were calculated with the most recent computer program for this purpose, the CARI-5E from the United States Civil Aviation Authority. The other major sources of information used as basis for this work is the collection of old SAS time tables found the the SAS Museum at Fornebu Airport in Oslo, and information provided by members of the Pilots Association in Norway.

  14. Correlated changes in occlusal pattern and diet in stem Murinae during the onset of the radiation of Old World rats and mice.

    Science.gov (United States)

    Tiphaine, Coillot; Yaowalak, Chaimanee; Cyril, Charles; Helder, Gomes-Rodrigues; Jacques, Michaux; Paul, Tafforeau; Monique, Vianey-Liaud; Laurent, Viriot; Vincent, Lazzari

    2013-11-01

    Adaptive radiations in mammals are sometimes associated with the emergence of key dental innovations facilitating food processing and masticatory movements. The dietary aspects of such innovations constitute an important focus in evolutionary biology. Murine rodents, which originated during middle Miocene, currently constitute the largest extant mammalian subfamily. Their adaptive radiation combines an original chewing motion with a peculiar occlusal pattern. The fossil record clearly establishes the timing of acquisitions of those innovations, and the aim of our study was to estimate the dietary changes associated with each of them. Fossil taxa phylogenetically closest to Murinae were investigated through the use of geographic information system applied on maps obtained from first upper molars digitized by X-ray synchrotron microtomography. This methodology enables estimation of quantitative topographic descriptors of the dietary specializations of the molar crown. The peculiar forwardly directed chewing motion acquired by stem Murinae may have been a key innovation allowing the invasion of an insectivorous dietary niche. The further radiation of crown Murinae coincides with the return to the plant-dominated omnivorous dietary niche of their distant ancestors through the acquisition of new morphological traits. The retention of the forwardly directed chewing motion by the crown Murinae could have become a competitive advantage in the context of a more generalist diet.

  15. Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model

    Directory of Open Access Journals (Sweden)

    Mortazavi S. M. J.

    2015-09-01

    Full Text Available Background: The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. Materials and Methods: In this study that was aimed at investigating the effects of exposure to radiofrequency (RF radiation emitted by a GSM mobile phone on the pattern of contraction in frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz, pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. Results: Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions

  16. Patterns of failure after radical prostatectomy in prostate cancer - implications for radiation therapy planning after (68)Ga-PSMA-PET imaging.

    Science.gov (United States)

    Schiller, Kilian; Sauter, K; Dewes, S; Eiber, M; Maurer, T; Gschwend, J; Combs, S E; Habl, G

    2017-09-01

    Salvage radiotherapy (SRT) after radical prostatectomy (RPE) and lymphadenectomy (LAE) is the appropriate radiotherapy option for patients with persistent/ recurrent prostate cancer (PC). (68)Ga-PSMA-PET imaging has been shown to accurately detect PC lesions in a primary setting as well as for local recurrence or for lymph node (LN) metastases. In this study we evaluated the patterns of recurrence after RPE in patients with PC, putting a highlight on the differentiation between sites that would have been covered by a standard radiation therapy (RT) field in consensus after the RTOG consensus and others that would have not. Thirty-one out of 83 patients (37%) with high-risk PC were the subject of our study. Information from (68)Ga-PSMA-PET imaging was used to individualize treatment plans to include suspicious lesions as well as possibly boost sites with tracer uptake in LN or the prostate bed. For evaluation, (68)Ga-PSMA-PET-positive LN were contoured in a patient dataset with a standard lymph drainage (RTOG consensus on CTV definition of pelvic lymph nodes) radiation field depicting color-coded nodes that would have been infield or outfield of that standard lymph drainage field and thereby visualizing typical patterns of failure of a "blind" radiation therapy after RPE and LAE. Compared to negative conventional imaging (CT/MRI), lesions suspicious for PC were detected in 27/31 cases (87.1%) by (68)Ga-PSMA-PET imaging, which resulted in changes to the radiation concept. There were 16/31 patients (51.6%) that received a simultaneous integrated boost (SIB) to a subarea of the prostate bed (in only three cases this dose escalation would have been planned without the additional knowledge of (68)Ga-PSMA-PET imaging) and 18/31 (58.1%) to uncommon (namely presacral, paravesical, pararectal, preacetabular and obturatoric) LN sites. Furthermore, 14 patients (45.2%) had a changed TNM staging result by means of (68)Ga-PSMA-PET imaging. Compared to conventional CT or MRI

  17. Analysis of the impact of fault mechanism radiation patterns on macroseismic fields in the epicentral area of 1998 and 2004 Krn Mountains earthquakes (NW Slovenia).

    Science.gov (United States)

    Gosar, Andrej

    2014-01-01

    Two moderate magnitude (Mw = 5.6 and 5.2) earthquakes in Krn Mountains occurred in 1998 and 2004 which had maximum intensity VII-VIII and VI-VII EMS-98, respectively. Comparison of both macroseismic fields showed unexpected differences in the epicentral area which cannot be explained by site effects. Considerably, different distribution of the highest intensities can be noticed with respect to the strike of the seismogenic fault and in some localities even higher intensities have been estimated for the smaller earthquake. Although hypocentres of both earthquakes were only 2 km apart and were located on the same seismogenic Ravne fault, their focal mechanisms showed a slight difference: almost pure dextral strike-slip for the first event and a strike-slip with small reverse component on a steep fault plane for the second one. Seismotectonically the difference is explained as an active growth of the Ravne fault at its NW end. The radiation patterns of both events were studied to explain their possible impact on the observed variations in macroseismic fields and damage distribution. Radiation amplitude lobes were computed for three orthogonal directions: radial P, SV, and SH. The highest intensities of both earthquakes were systematically observed in directions of four (1998) or two (2004) large amplitude lobes in SH component (which corresponds mainly to Love waves), which have significantly different orientation for both events. On the other hand, radial P direction, which is almost purely symmetrical for the strike-slip mechanism of 1998 event, showed for the 2004 event that its small reverse component of movement has resulted in a very pronounced amplitude lobe in SW direction where two settlements are located which expressed higher intensities in the case of the 2004 event with respect to the 1998 one. Although both macroseismic fields are very complex due to influences of multiple earthquakes, retrofitting activity after 1998, site effects, and sparse

  18. Mapping Patterns of Local Recurrence After Pancreaticoduodenectomy for Pancreatic Adenocarcinoma: A New Approach to Adjuvant Radiation Field Design

    Energy Technology Data Exchange (ETDEWEB)

    Dholakia, Avani S.; Kumar, Rachit [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Raman, Siva P. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Moore, Joseph A.; Ellsworth, Susannah; McNutt, Todd [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Laheru, Daniel A.; Jaffee, Elizabeth [Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Cameron, John L. [Department of Surgery, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Tran, Phuoc T. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hobbs, Robert F. [Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Wolfgang, Christopher L. [Department of Surgery, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); and others

    2013-12-01

    Purpose: To generate a map of local recurrences after pancreaticoduodenectomy (PD) for patients with resectable pancreatic ductal adenocarcinoma (PDA) and to model an adjuvant radiation therapy planning treatment volume (PTV) that encompasses a majority of local recurrences. Methods and Materials: Consecutive patients with resectable PDA undergoing PD and 1 or more computed tomography (CT) scans more than 60 days after PD at our institution were reviewed. Patients were divided into 3 groups: no adjuvant treatment (NA), chemotherapy alone (CTA), or chemoradiation (CRT). Cross-sectional scans were centrally reviewed, and local recurrences were plotted to scale with respect to the celiac axis (CA), superior mesenteric artery (SMA), and renal veins on 1 CT scan of a template post-PD patient. An adjuvant clinical treatment volume comprising 90% of local failures based on standard expansions of the CA and SMA was created and simulated on 3 post-PD CT scans to assess the feasibility of this planning approach. Results: Of the 202 patients in the study, 40 (20%), 34 (17%), and 128 (63%) received NA, CTA, and CRT adjuvant therapy, respectively. The rate of margin-positive resections was greater in CRT patients than in CTA patients (28% vs 9%, P=.023). Local recurrence occurred in 90 of the 202 patients overall (45%) and in 19 (48%), 22 (65%), and 49 (38%) in the NA, CTA, and CRT groups, respectively. Ninety percent of recurrences were within a 3.0-cm right-lateral, 2.0-cm left-lateral, 1.5-cm anterior, 1.0-cm posterior, 1.0-cm superior, and 2.0-cm inferior expansion of the combined CA and SMA contours. Three simulated radiation treatment plans using these expansions with adjustments to avoid nearby structures were created to demonstrate the use of this treatment volume. Conclusions: Modified PTVs targeting high-risk areas may improve local control while minimizing toxicities, allowing dose escalation with intensity-modulated or stereotactic body radiation therapy.

  19. 频率与方向图可重构微带天线设计%Design of frequency and radiation pattern reconfigurable microstrip antenna

    Institute of Scientific and Technical Information of China (English)

    赵轶卓; 陈春红; 马伟男; 邾志民

    2015-01-01

    This paper presents a microstrip patch antenna with reconfigurable frequency and pattern to meet the needs of wireless communication system miniaturization and antenna multifunction. The configuration consists of a radiation patch with an U-shaped slot and two symmetrical parasitic patches. The reconfigurations of frequency and pattern can be achieved by changing the operating states of the PIN diode on the U-shaped slot and parasitic patches. Simulation and test results show that the antenna resonates at 5. 2 GHz or 5. 8 GHz, at the same time, the beam deflection and broadening can be achieved at both of the resonant frequencies. The reconfigurable frequencies and radiation patterns can be achieved by adopting the structure of a microstrip antenna, and the characteristic of multifunction is realized.%为了满足无线通信系统小型化和天线多功能的需求,设计了一种频率和方向图可重构的微带贴片天线. 该天线由一个带U型槽的辐射贴片和左右对称的寄生贴片构成,通过改变辐射贴片上U型槽和寄生贴片上PIN(正-本-负)二极管的工作状态来实现天线的工作频率和方向图的改变. 仿真和测试结果表明:天线的谐振频率可以在5 . 2 GHz和5 . 8 GHz之间切换,同时在两个频点都可以实现波束的左右偏转和展宽. 采用这种结构的微带天线可以同时实现频率和方向图的重构,从而实现天线的多功能.

  20. Intensity-modulated radiation therapy use for the localized treatment of thyroid cancer: Nationwide practice patterns and outcomes.

    Science.gov (United States)

    Goffredo, Paolo; Robinson, Timothy J; Youngwirth, Linda M; Roman, Sanziana A; Sosa, Julie A

    2016-09-01

    In the absence of randomized data, the optimal approach to adjuvant radiation therapy in locally advanced thyroid cancer remains unclear. We employed a large retrospective analysis to assess the best available evidence of a potential beneficial impact of intensity-modulated versus 3D-conformal radiotherapy (IMRT vs. 3D-CT). Retrospective analysis of adult thyroid cancer diagnosed between 2004 and 2011 within the National Cancer Database. Among patients treated with radiation therapy (N = 855), the use of IMRT (N = 437) increased among both comprehensive and academic centers (both p HR, 0.67; 95 % CI, 0.40-1.10; p = 0.115). This study presents the largest cohort to date examining receipt of IMRT in patients with locally advanced thyroid cancer and demonstrates an association between IMRT, treatment at a tertiary care center, higher total dose, and comparable or superior outcomes compared to patients treated with 3D conformal techniques despite more adverse disease features. In the absence of adequately powered prospective randomized trials, our retrospective analysis provides empirical evidence to support the use in these patients of dose escalation and IMRT, particularly at tertiary care centers.

  1. Medicina array demonstrator: calibration and radiation pattern characterization using a UAV-mounted radio-frequency source

    Science.gov (United States)

    Pupillo, G.; Naldi, G.; Bianchi, G.; Mattana, A.; Monari, J.; Perini, F.; Poloni, M.; Schiaffino, M.; Bolli, P.; Lingua, A.; Aicardi, I.; Bendea, H.; Maschio, P.; Piras, M.; Virone, G.; Paonessa, F.; Farooqui, Z.; Tibaldi, A.; Addamo, G.; Peverini, O. A.; Tascone, R.; Wijnholds, S. J.

    2015-06-01

    One of the most challenging aspects of the new-generation Low-Frequency Aperture Array (LFAA) radio telescopes is instrument calibration. The operational LOw-Frequency ARray (LOFAR) instrument and the future LFAA element of the Square Kilometre Array (SKA) require advanced calibration techniques to reach the expected outstanding performance. In this framework, a small array, called Medicina Array Demonstrator (MAD), has been designed and installed in Italy to provide a test bench for antenna characterization and calibration techniques based on a flying artificial test source. A radio-frequency tone is transmitted through a dipole antenna mounted on a micro Unmanned Aerial Vehicle (UAV) (hexacopter) and received by each element of the array. A modern digital FPGA-based back-end is responsible for both data-acquisition and data-reduction. A simple amplitude and phase equalization algorithm is exploited for array calibration owing to the high stability and accuracy of the developed artificial test source. Both the measured embedded element patterns and calibrated array patterns are found to be in good agreement with the simulated data. The successful measurement campaign has demonstrated that a UAV-mounted test source provides a means to accurately validate and calibrate the full-polarized response of an antenna/array in operating conditions, including consequently effects like mutual coupling between the array elements and contribution of the environment to the antenna patterns. A similar system can therefore find a future application in the SKA-LFAA context.

  2. Study of far-field pressure wavelet of air-gun bubble based on p otential flow theory%基于势流理论的气枪气泡远场压力子波特性研究

    Institute of Scientific and Technical Information of China (English)

    叶亚龙; 李艳青; 张阿漫

    2014-01-01

    The study of far-field pressure wavelet of air-gun bubble is the basic research of air-gun sources. In this paper, a boundary element bubble model is established to simulate the dynamics of bubble, and an energy equivalent method is put forward to solve the bottleneck of bubble jet. In our simplified model, the bubble model takes into consideration the thermodynamic factors such as heat transfer and gas release, and the numerical results agree with the data of Nucleus software well. Based on the established model, the influence of heat transfer coefficient, air-gun firing time, and specific heat at constant volume on the pressure wavelet are studied. Finally, the three-dimensional bubble merging numerical method is put forward, which is an expansion of the axisymmetric model. Thus, the preliminary study of coherent air-gun is conducted, especially the influence of the space between two bubbles on the wavelet. This paper provides a reference for the research of air-gun.%气枪气泡的远场压力子波特性研究是研究气枪震源的基础,本文在前人研究基础上建立了三维边界元气泡动力学模型,并针对气泡射流这一技术瓶颈提出了能量等效算法。再在上述模型中加入了简化的热力学模型,考虑了气枪释放气体以及气泡传热等热力学因素,将上面模型计算结果和Nucleus软件模拟结果对比,两者符合良好,并以此为基础探讨了传热系数、气枪发射时间、气体等体比热容对气枪主要参数的影响规律。最后将轴对称气泡融合技术拓展到三维边界元模型,对相干枪进行初步研究,探讨了气枪间距对压力子波的影响规律,旨在为气枪的研究提供参考。

  3. Exploring Optimization of Supersonic Wing Thickness Distribution Using FCE (Far-field Composite Element) Method%基于FCE方法的超声速机翼厚度分布优化

    Institute of Scientific and Technical Information of China (English)

    关晓辉; 李占科; 宋笔锋

    2012-01-01

    远场组元(Far-field Composite Element,FCE)激波阻力优化方法是基于类别形状函数变换(Class Shape Transformation,CST)参数化方法发展出的一种超声速飞行器气动外形优化方法.文章使用CST参数化方法对超声速客机的大后掠机翼进行外形参数化,并以机翼容积和局部相对厚度为约束条件,使用FCE方法对其厚度分布进行以激波阻力最小为设计目标的快速优化.与原机翼相比,FCE优化方法使机翼激波阻力系数降低达61%,是超声速飞行器概念设计阶段降低激波阻力十分有用的优化方法.%Developed from the class shape transformation (CST) geometric parameterization method, the FCE wave drag optimization method is a new aerodynamic shape optimization method for supersonic aircraft. We use the CST parameterization method to perform the shape parameterization of a typical and large swept wing model of a supersonic aircraft. Sections 1 and 2 of the full paper explain our exploration, whose core consists of; (1) under the constraints of the total volume and local thicknesses of the swept wing, we carry out the quick optimization of the wing thickness distribution, aiming to achieve minimum wave drag; (2 ) we use the supersonic area rule to calculate the wave drag and to optimize the shape parameters of the swept wing with the Lagrange multiplier method, thus requiring no iteration and reducing computation complexity. The optimization results, given in Table 1 and Figs. 4, 5 and 6, and their analysis show preliminarily that, compared with the baseline wing model, our optimization method can reduce the wave drag coefficient by 61% , thus being a useful method for aerodynamic shape optimization so as to reduce the wave drag at the stage of the conceptual design of a supersonic aircraft.

  4. 艾里光束的远场特性及其演化规律%Propagation characteristics in the far-field and evolution regular of Airy beam

    Institute of Scientific and Technical Information of China (English)

    程振; 楚兴春; 赵尚弘; 邓博于; 张曦文

    2015-01-01

    The propagation characteristics of Airy beam in the far-field were detailly studied, which start with the theoretical foundation, including the evolution process of intensity distribution, spot diameter and Power in the Bucket (PIB). The change regular of intensity distribution was investigated with the truncation factor a and the arbitrary scale in the transverse x0 and how do a and x0 influence the propagation Distance with Keeping Non-diffraction (DKNd), the Distance in which the Evolution became similar Guassian(DEG) and Self-bending Degree(SbD). The research shows that in the evolution process of intensity distribution which transforms into similar Guassian, the DKNd, DEG and SbD increase with the increase of x0, the DKNd and DEG decrease with the increase of a and a has no effect on SbD. The evolution regular of spot diameter and PIB was also researched. The research shows that the spot diameter fistly remain unchanged and then increases, PIB firstly decreases, then increases and is 0.76 finally in the propagation progress under different values of a.%从艾里光束的理论基础出发,详细研究了艾里光束的远场传输特性,包括场强分布、光斑直径和桶中功率(Power in the Bucket,PIB)的演化过程.探讨了场强分布随截断因子a和任意横向刻度x0的变化规律,以及a和x0对艾里光束保持无衍射性质传输的距离 (Distance with Keeping Non-diffraction,DKNd)、演化成类高斯分布的距离(Distance in which the Evolution became similar Guassian, DEG)和自弯曲程度(Self-bending Degree,SbD)的影响.研究发现:场强分布在演化成类高斯分布过程中,DKNd、DEG和SbD都随着x0的增大而增大,DKNd和DEG随a的增大而减小,a对SbD无影响.研究了艾里光束的光斑直径和PIB的演化规律, 发现在a值不同的情况下,在传输过程中光斑直径先保持不变后增加,PIB先减小后增大,最终等于0.76.

  5. Dependence of radiation dose on the behavioral patterns among school children: a retrospective analysis 18 to 20 months following the 2011 Fukushima nuclear incident in Japan.

    Science.gov (United States)

    Nomura, Shuhei; Tsubokura, Masaharu; Furutani, Tomoyuki; Hayano, Ryugo S; Kami, Masahiro; Kanazawa, Yukio; Oikawa, Tomoyoshi

    2016-01-01

    After radioactive incidents, the exposure risk in daily activities among children is a major public concern. However, there are limited methods available for evaluation of this risk, which is essential to future health risk management. To this end, this study assessed the relationship between behavioral patterns of school children and radiation exposure for a period of 18-20 months following the 2011 Fukushima nuclear incident. The assessed population comprised 520 school children from Minamisoma city, located 20 km north of the nuclear plant. Data for the doses were obtained using individual dosimeters and from results of a behavior survey administered by the City Office. The mean value of the doses in the study period was 0.34 mSv, with a standard deviation of 0.14 mSv, indicating an annual dose of ∼1.36 mSv, which includes doses from natural sources. Our results showed that behavior with respect to outdoor activities had no statistically significant relationship to the dose. A 0.1 μSv/h increase in the air dose rate at home was associated with a 10% increase in the dose; however, a 0.01 μSv/h increase in the air dose rate on the school grounds was associated with a 2% increase in the dose. This study indicates that the air contamination levels at the places where children spend most of their day are the significant predictors of the dose, as opposed to the levels at those outdoor locations in which short periods of time spent. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  6. Simulated Seasonal Spatio-Temporal Patterns of Soil Moisture, Temperature, and Net Radiation in a Deciduous Forest

    Science.gov (United States)

    Ballard, Jerrell R., Jr.; Howington, Stacy E.; Cinnella, Pasquale; Smith, James A.

    2011-01-01

    The temperature and moisture regimes in a forest are key components in the forest ecosystem dynamics. Observations and studies indicate that the internal temperature distribution and moisture content of the tree influence not only growth and development, but onset and cessation of cambial activity [1], resistance to insect predation[2], and even affect the population dynamics of the insects [3]. Moreover, temperature directly affects the uptake and metabolism of population from the soil into the tree tissue [4]. Additional studies show that soil and atmospheric temperatures are significant parameters that limit the growth of trees and impose treeline elevation limitation [5]. Directional thermal infrared radiance effects have long been observed in natural backgrounds [6]. In earlier work, we illustrated the use of physically-based models to simulate directional effects in thermal imaging [7-8]. In this paper, we illustrated the use of physically-based models to simulate directional effects in thermal, and net radiation in a adeciduous forest using our recently developed three-dimensional, macro-scale computational tool that simulates the heat and mass transfer interaction in a soil-root-stem systems (SRSS). The SRSS model includes the coupling of existing heat and mass transport tools to stimulate the diurnal internal and external temperatures, internal fluid flow and moisture distribution, and heat flow in the system.

  7. Columnar aerosol optical and radiative properties according to season and air mass transport pattern over East Asia.

    Science.gov (United States)

    Noh, Young M; Müller, Detlef; Lee, Hanlim; Lee, Kwonho; Kim, Young Joon

    2012-08-01

    The column-integrated optical and radiative properties of aerosols in the downwind area of East Asia were investigated based on sun/sky radiometer measurements performed from February 2004 to June 2005 at Gwangju (35.23° N, 126.84° E) and Anmyeon (36.54° N, 126.33° E), Korea. The observed aerosol data were analyzed for differences among three seasons: spring (March-May), summer (June-August), and autumn/winter (September-February). The data were also categorized into five types depending on the air mass origin in arriving in the measurement sites: (a) from a northerly direction in spring (S(N)), (b) from a westerly direction in spring (S(W)), (c) cases with a low Ångström exponent (air mass origin. The forcing efficiency in summer was -131.7 and -125.6 W m(-2) at the surface in Gwangju and Anmyeon, respectively. These values are lower than those under the atmospheric conditions of spring and autumn/winter. The highest forcing efficiencies in autumn/winter were -214.3 and -255.9 W m(-2) at the surface in Gwangju and Anmyeon, respectively, when the air mass was transported from westerly directions.

  8. Linear energy transfer and track pattern recognition of secondary radiation generated in hadron therapy beam in a PMMA target

    Science.gov (United States)

    Opalka, L.; Granja, C.; Hartmann, B.; Jakubek, J.; Jaekel, O.; Martisikova, M.; Pospisil, S.; Solc, J.

    2013-02-01

    Hadron therapy uses ion beams for irradiation of cancerous tissue taking advantage of the highly localized dose deposition in the target tumor. For a correct estimation of dose deposited in tissue surrounding the target it is necessary to consider also the contribution of energetic secondary radiation generated by primary ions. It was already experimentally demonstrated that this contribution can be measured using the semiconductor pixel detector Timepix (256 × 256 pixels with 55 μm pitch) visualizing traces of secondary particles. The resolving power of the detector enables the differentiation of traces of different types of particles. In this work we studied the possibilities of determination of different types of secondary particles in correlation with their flight direction. Such identification allows correct assignment of dose for each type of particle. The distribution of secondary particles was compared to Monte Carlo simulations. Measurements were performed with a PMMA target irradiated with a therapeutic carbon beam at the Heidelberg Ion-Beam Therapy Center (HIT).

  9. Radiating on oceanic islands: patterns and processes of speciation in the land snail genus Theba (Risso 1826.

    Directory of Open Access Journals (Sweden)

    Carola Greve

    Full Text Available Island radiations have played a major role in shaping our current understanding of allopatric, sympatric and parapatric speciation. However, the fact that species divergence correlates with island size emphasizes the importance of geographic isolation (allopatry in speciation. Based on molecular and morphological data, we investigated the diversification of the land snail genus Theba on the two Canary Islands of Lanzarote and Fuerteventura. Due to the geological history of both islands, this study system provides ideal conditions to investigate the interplay of biogeography, dispersal ability and differentiation in generating species diversity. Our analyses demonstrated extensive cryptic diversification of Theba on these islands, probably driven mainly by non-adaptive allopatric differentiation and secondary gene flow. In a few cases, we observed a complete absence of gene flow among sympatrically distributed forms suggesting an advanced stage of speciation. On the Jandía peninsula genome scans suggested genotype-environment associations and potentially adaptive diversification of two closely related Theba species to different ecological environments. We found support for the idea that genetic differentiation was enhanced by divergent selection in different environments. The diversification of Theba on both islands is therefore best explained by a mixture of non-adaptive and adaptive speciation, promoted by ecological and geomorphological factors.

  10. Thermotronics: Towards Nanocircuits to Manage Radiative Heat Flux

    Science.gov (United States)

    Ben-Abdallah, Philippe; Biehs, Svend-Age

    2017-02-01

    The control of electric currents in solids is at the origin of the modern electronics revolution that has driven our daily life since the second half of 20th century. Surprisingly, to date, there is no thermal analogue for a control of heat flux. Here, we summarise the very last developments carried out in this direction to control heat exchanges by radiation both in near and far-field in complex architecture networks.

  11. Thermotronics. Towards nanocircuits to manage radiative heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Abdallah, Philippe [Univ. Paris-Sud 11, Palaiseau (France). Lab. Charles Fabry; Sherbrooke Univ., PQ (Canada). Dept. of Mechanical Engineering; Biehs, Svend-Age [Oldenburg Univ. (Germany). Inst. fuer Physik

    2017-05-01

    The control of electric currents in solids is at the origin of the modern electronics revolution that has driven our daily life since the second half of 20{sup th} century. Surprisingly, to date, there is no thermal analogue for a control of heat flux. Here, we summarise the very last developments carried out in this direction to control heat exchanges by radiation both in near and far-field in complex architecture networks.

  12. Time trends in incidence of cutaneous melanoma by detailed anatomical location and patterns of ultraviolet radiation exposure: a retrospective population-based study.

    Science.gov (United States)

    Gordon, Daniela; Gillgren, Peter; Eloranta, Sandra; Olsson, Henrik; Gordon, Max; Hansson, Johan; Smedby, Karin E

    2015-08-01

    Given the wide public health implications of the melanoma epidemic, ultraviolet radiation (UVR) exposure patterns contributing to cutaneous melanoma development should be clearly identified. To describe time trends of anatomic sites of melanoma using a UVR exposure model based on clothing and sun habits, we reviewed the medical records of all patients diagnosed with primary invasive melanoma or melanoma in situ (MIS) during the years 1977-78, 1983-84, 1989-90, 1995-96, and 2000-01 (n=3058) in one healthcare region of Sweden. Age-standardized incidence rates and relative risks (RRs) of melanoma by calendar period were estimated for intermittent and chronic UVR exposure sites. From 1977-78 to 2000-01, the incidence rates of all melanomas at intermittent UVR exposure sites increased both among men (7.8-16.5/10 person-years) and among women (7.6-14.6/10 person-years), with a sex-adjusted and age-adjusted RR of 2.1 [95% confidence interval (CI) 1.8-2.4, Ptrendexposure sites, the male sex was positively associated with central (core) areas (chest, back, neck, shoulders, thighs; RR 1.7, 95% CI 1.5-1.9), but negatively associated with peripheral areas (lateral arms, lower legs, dorsum of feet; RR 0.3, 95% CI 0.3-0.4), compared with the female sex. Sex-specific intermittent UVR exposure patterns drove the observed increase in melanoma incidence, whereas chronic UVR exposure contributed less.

  13. 基于三维SAR成像的RCS近远场变换方法研究%Research on Methods of Targets’ RCS Near-field-to-far-field Transformation Based on 3-D SAR Imaging

    Institute of Scientific and Technical Information of China (English)

    张晓玲; 陈明领; 廖可非; 师君; 韦顺军

    2015-01-01

    微波3维成像能够准确地从背景噪声中分离出目标的散射信息,适用于外场目标电磁(EM)散射特性的分析和研究,因而从3维合成孔径雷达(SAR)成像的角度研究目标电磁的散射特性是目前的一个新兴的热门课题。该文以此为背景,首先从Stratton-Chu积分方程出发详细推导3维SAR的近场波数域成像过程,解释3维SAR成像的物理意义;然后阐述基于3维SAR成像的雷达散射截面积(RCS)近远场变换原理,介绍3维SAR图像的散射中心提取方法,给出基于3维SAR成像的RCS近远场变换算法;最后通过FEKO软件进行了仿真实验,得到了5个点目标的RCS近远场变换的方位特性曲线和频率特性曲线,并通过与理论情况的对比,验证该算法在RCS近远场变换技术中的有效性。%Microwave 3-D imaging technique can accurately separate and extract the attractive targets from the background noise. So it can be utilized to analyze and study the ElectroMagnetic (EM) scattering characteristics of the outfield targets. Thus researching the EM scattering characteristics of targets from the perspective of 3-D SAR imaging is becoming an emerging hot field. Based on the background above, firstly, the near field 3-D imaging process in wave-number domain is deduced from the Stratton-Chu integral equation and the physical meaning of 3-D SAR imaging is explained. Then, the principle of targets’ Radar Cross Section (RCS) Near-Field-to-Far-Field Transformation (NFFFT) based on 3-D SAR imaging is elaborated and the method of scattering center extraction from 3-D SAR image is introduced and the algorithm of targets’ RCS NFFFT based on 3-D SAR imaging technique is presented. Finally, though some experiments using the FEKO software, five scattering points’ observing angle characteristic curve and frequency characteristic curve are gotten. Through the comparative experiments with the ideal situation, the effectiveness of the RCS

  14. Dosimetric evaluation of multi-pattern spatially fractionated radiation therapy using a multi-leaf collimator and collapsed cone convolution superposition dose calculation algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Stathakis, Sotirios [Department of Radiation Oncology, University of Texas Health Science Center San Antonio, 7979 Wurzbach Rd, San Antonio, TX 78229 (United States)], E-mail: stathakis@uthscsa.edu; Esquivel, Carlos; Gutierrez, Alonso N.; Shi, ChengYu; Papanikolaou, Niko [Department of Radiation Oncology, University of Texas Health Science Center San Antonio, 7979 Wurzbach Rd, San Antonio, TX 78229 (United States)

    2009-10-15

    Purpose: In this paper, we present an alternative to the originally proposed technique for the delivery of spatially fractionated radiation therapy (GRID) using multi-leaf collimator (MLC) shaped fields. We employ the MLC to deliver various pattern GRID treatments to large solid tumors and dosimetrically characterize the GRID fields. Methods and materials: The GRID fields were created with different open to blocked area ratios and with variable separation between the openings using a MLC. GRID designs were introduced into the Pinnacle{sup 3} treatment planning system, and the dose was calculated in a water phantom. Ionization chamber and film measurements using both Kodak EDR2 and Gafchromic EBT film were performed in a SolidWater phantom to determine the relative output of each GRID design as well as its spatial dosimetric characteristics. Results: Agreement within 5.0% was observed between the Pinnacle{sup 3} predicted dose distributions and the measurements for the majority of experiments performed. A higher magnitude of discrepancy (15%) was observed using a high photon beam energy (18 MV) and small GRID opening. Skin dose at the GRID openings was higher than the corresponding open field by a factor as high as three for both photon energies and was found to be independent of the open-to-blocked area ratio. Conclusion: In summary, we reaffirm that the MLC can be used to deliver spatially fractionated GRID therapy and show that various GRID patterns may be generated. The Pinnacle{sup 3} TPS can accurately calculate the dose of the different GRID patterns in our study to within 5% for the majority of the cases based on film and ion chamber measurements. Disadvantages of MLC-based GRID therapy are longer treatment times and higher surface doses.

  15. Asymmetric active nano-particles for directive near-field radiation

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Thorsen, Rasmus O.

    2016-01-01

    In this work, we demonstrate the potential of cylindrical active coated nano-particles with certain geometrical asymmetries for the creation of directive near-field radiation. The particles are excited by a near-by magnetic line source, and their performance characteristics are reported in terms...... of radiated power, near-field and power flow distributions as well as the far-field directivity....

  16. Analyses of patterns-of-failure and prognostic factors according to radiation fields in early-stage Hodgkin lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, Lorraine; Guillerm, Sophie; Menard, Jean; Hennequin, Christophe; Quero, Laurent [Saint Louis Hospital, Radiation Oncology Department, Paris (France); Amorin, Sandy; Brice, Pauline [Saint Louis Hospital, AP-HP, Hematooncology Department, Paris (France)

    2017-02-15

    Doses and volumes of radiation therapy (RT) for early stages of Hodgkin lymphoma (HL) have been reduced over the last 30 years. Combined modality therapy (CMT) is currently the standard treatment for most patients with early-stage HL. The aim of this study was to analyze the site of relapse after RT according to the extent of radiation fields. Between 1987 and 2011, 427 patients were treated at our institution with RT ± chemotherapy for stage-I/II HL. Among these, 65 patients who experienced a relapse were retrospectively analyzed. Most patients had nodular sclerosis histology (86 %) and stage-II disease (75.9 %). Bulky disease was present in 21 % and 56 % of patients belonged to the unfavorable risk group according to European Organization for Research and Treatment of Cancer (EORTC)/The Lymphoma Study Association (LYSA) definitions. CMT was delivered to 91 % of patients. All patients received RT with doses ranging from 20 to 45 Gy (mean = 34 ± 5.3 Gy). The involved-field RT technique was used in 59 % of patients. The mean time between diagnosis and relapse was 4.2 years (range 0.3-24.5). Out-of-field relapses were suffered by 53 % of patients. Relapses occurred more frequently at out-of-field sites in patients with a favorable disease status, whereas in-field relapses were associated with bulky mediastinal disease. Relapses occurred later for favorable compared with the unfavorable risk group (3.5 vs. 2.9 years, p = 0.5). From multivariate analyses, neither RT dose nor RT field size were predictive for an in-field relapse (p = 0.25 and p = 0.8, respectively), only bulky disease was predictive (p = 0.018). In patients with bulky disease, RT dose and RT field size were not predictive for an in-field relapse. In this subgroup of patients, chemotherapy should be intensified. We confirmed the bad prognosis of early relapses. (orig.) [German] Waehrend der letzten 30 Jahre wurden die Strahlentherapie-(RT-)Dosis und die RT-Volumina fuer die Behandlung der Fruehstadien

  17. Size reduction and radiation pattern shaping of multi-fed DCC slot antennas used in conformal microwave array hyperthermia applicators.

    Science.gov (United States)

    Maccarini, Paolo F; Arunachalam, Kavitha; Martins, Carlos D; Stauffer, Paul R

    2009-02-23

    The use of conformal antenna array in the treatment of superficial diseases can significantly increase patient comfort while enhancing the local control of large treatment area with irregular shapes. Originally a regular square multi-fed slot antenna (Dual Concentric Conductor - DCC) was proposed as basic unit cell of the array. The square DCC works well when the outline of the treatment area is rectangular such as in the main chest or back area but is not suitable to outline diseases spreading along the armpit and neck area. In addition as the area of the patch increases, the overall power density decreases affecting the efficiency and thus the ability to deliver the necessary thermal dose with medium power amplifier (antennas is preferable as the disease is more accurately contoured and the lower power requirement for the amplifiers correlates with system reliability, durability, linearity and overall reduced cost. For such reason we developed a set of design rules for multi-fed slot antennas with irregular contours and we implemented a design that reduce the area while increasing the perimeter of the slot, thus increasing the antenna efficiency and the power density. The simulation performed with several commercial packages (Ansoft HFSS, Imst Empire, SemcadX and CST Microwave Studio) show that the size reducing method can be applied to several shapes and for different frequencies. The SAR measurements of several DCCs are performed using an in-house high resolution scanning system with tumor equivalent liquid phantom both at 915 MHz for superficial hyperthermia systems in US) and 433 MHz (Europe). The experimental results are compared with the expected theoretical predictions and both simulated and measured patterns of single antennas of various size and shapes are then summed in various combinations using Matlab to show possible treatment irregular contours of complex diseases. The local control is expected to significantly improve while maintaining the patient

  18. Radiation therapy of benign diseases: patterns of care study in Germany; Strahlentherapie von gutartigen Erkrankungen: eine Bestandsaufnahme fuer Deutschland

    Energy Technology Data Exchange (ETDEWEB)

    Seegenschmiedt, M.H. [Alfried Krupp Krankenhaus Essen (Germany). Klinik fuer Radioonkologie, Strahlentherapie und Nuklearmedizin; Katalinic, A. [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. fuer Medizinische Statistik und Dokumentation; Makoski, H.B. [Staedtische Kliniken Duisburg (Germany). Strahlenklinik; Haase, W. [St. Vincentius Krankenhaus Karlsruhe (Germany). Klinik fuer Radioonkologie und Strahlentherapie; Gademann, G. [Magdeburg Univ. (Germany). Klinik fuer Strahlentherapie; Hassenstein, E. [Krankenhaus Nordwest, Frankfurt am Main (Germany). Radioonkologische Klinik

    1999-11-01

    A questionnaire was mailed in 3 years (1994, 1995, 1996) to all radiation facilities in Germany, which assessed equipment, indications, number of patients and treatment concepts. A total of 134 (88%) institutions returned all requested data: 22 in East and 112 in West Germany; 30 in university and 104 in community/private hospitals. The average data of each institution and of all institutions were analyzed for frequencies and ratios between different regions and institutions. A mean of 2 (range 1 to 7) megavoltage (Linac/Cobalt 60) and 1.4 (range 0 to 4) orthovoltage units were available per institution; 32 (24%) institutions had no orthovoltage equipment. A mean of 20,082 patients were treated per year: 456 (2%) for inflammatory diseases (221 hidradenitis, 78 nail bed infection, 23 parotitis, 134 not specified), 12,600 (63%) for degenerative diseases (2,711 peritendinitis humeroscapularis, 1,555 epicondylitis humeri, 1,382 heel spur, 2,434 degenerative osteoarthritis, 4,518 not specified), 927 (5%) for hypertrophic diseases (146 Dupuytren's contracture, 382 keloids, 155 Peyronie's disease, 244 not specified), 1,210 (6%) for functional disorders (853 Graves' orbitopathy, 357 not specified), and 4,889 (24%) for other disorders (e.g. 3,680 heterotopic ossification prophylaxis). In univariate analysis, there were significant geographical (West vs East Germany) differences in the use of radiotherapy for inflammatory and degenerative disorders and institutional differences (university vs community/private hospitals) in the use of radiotherapy for hypertrophic and functional disorders (p<0.05). The prescribed dose concepts were mostly in the low dose range (<10 Gy), but varied widely and inconsistently within geographic regions and institution types. (orig./MG) [German] 1994, 1995 und 1996 wurde an alle strahlentherapeutischen Institutionen in Deutschland ein Fragebogen verschickt, mit dem technische Ausstattung, Indikationsspektrum, Patientenzahl und

  19. Radiation damage-controlled localization of alteration haloes in albite: implications for alteration types and patterns vis-à-vis mineralization and element mobilization

    Science.gov (United States)

    Pal, D. C.; Chaudhuri, T.

    2016-12-01

    Uraninite, besides occurring in other modes, occurs as inclusions in albite in feldspathic schist in the Bagjata uranium deposits, Singhbhum shear zone, India. The feldspathic schist, considered the product of Na-metasomatism, witnessed multiple hydrothermal events, the signatures of which are preserved in the alteration halo in albite surrounding uraninite. Here we report radiation damage-controlled localization of alteration halo in albite and its various geological implications. Microscopic observation and SRIM/TRIM simulations reveal that the dimension of the alteration halo is dependent collectively on the zone of maximum cumulative α dose that albite was subjected to and by the extent of dissolution of uraninite during alteration. In well-preserved alteration haloes, from uraninite to the unaltered part of albite, the alteration minerals are systematically distributed in different zones; zone-1: K-feldspar; zone-2: chlorite; zone-3: LREE-phase/pyrite/U-Y-silicate. Based on textures of alteration minerals in the alteration microdomain, we propose a generalized Na+➔K+➔H+ alteration sequence, which is in agreement with the regional-scale alteration pattern. Integrating distribution of ore and alteration minerals in the alteration zone and their geochemistry, we further propose multiple events of U, REE, and sulfide mineralization/mobilization in the Bagjata deposit. The alteration process also involved interaction of the hydrothermal fluid with uraninite inclusions resulting in resorption of uraninite, redistribution of elements, including U and Pb, and resetting of isotopic clock. Thus, our study demonstrates that alteration halo is a miniature scale-model of the regional hydrothermal alteration types and patterns vis-à-vis mineralization/mobilization. This study further demonstrates that albite is vulnerable to radiation damage and damage-controlled fluid-assisted alteration, which may redistribute metals, including actinides, from radioactive minerals

  20. Analysis on the Radiation Property of the Bounded Modes of Periodic Leaky-Wave Structure with Finite-Length Using a Hybrid Method.

    Science.gov (United States)

    Li, Zheng; Wang, Junhong; Duan, Jianjie; Zhang, Zhan; Chen, Meie

    2016-03-18

    In this paper the radiation property of the one-dimensional periodic leaky-wave structure is analysed using a new hybrid method, which involves the mode expansion method for expanding the periodic aperture field in terms of spatial harmonics and the method of effective radiation sections for transforming the expanded fields into far fields. Using this method, the radiation of each spatial harmonic can be achieved, and the contributions of the harmonics (especially the bounded modes) to the total radiation of the periodic leaky-wave structure can be calculated. The main findings in this paper demonstrate that the bounded modes in a finite length structure have obvious contribution to the far-field radiation, which was considered to be non-radiative and always ignored in the conventional researches.

  1. Stereotactic body radiation therapy for the treatment of early-stage minimally invasive adenocarcinoma or adenocarcnioma in situ (formerly bronchioloalveolar carcinoma: a patterns of failure analysis

    Directory of Open Access Journals (Sweden)

    Badiyan Shahed N

    2013-01-01

    Full Text Available Abstract Introduction Ongoing prospective trials exploring stereotactic body radiation therapy (SBRT for early stage non-small cell lung cancer (NSCLC often exclude minimally invasive adenocarcinoma or adenocarcnioma in situ, formerly bronchioloalveolar carcinoma (BAC, due to concerns for accurate target delineation on CT. We performed a patterns of failure analysis to compare outcomes between BAC and other NSCLC subtypes. Methods One hundred twenty patients with early stage NSCLC were treated with SBRT from 2004–2009. Pathologic confirmation of NSCLC was obtained in 97 patients. Radiotherapy was delivered according to RTOG guidelines. The log-rank test was used to compare outcomes between BAC and other NSCLC. Results Median follow-up was 29 months. The median SBRT dose was 5400 cGy. Thirteen patients had radiographically diagnosed BAC and five patients had biopsy confirmed BAC, of which two had both. The three-year local control was 100% for biopsy-proven or radiographically diagnosed BAC (n = 18 and 86% for all other NSCLC subtypes (n = 102 (p = 0.13. Likewise, no significant difference was detected between BAC and other NSCLC for 3-year regional failure (12% vs. 20%, p = 0.45, progression-free survival (57.6% vs. 53.5%, p = 0.84 or overall survival (35% vs. 47%, p = 0.66. There was a trend towards lower three-year rates of freedom from distant failure in patients with any diagnosis of BAC compared to those without (26% vs. 38%, p = 0.053. Conclusions Compared to other NSCLC subtypes, BAC appears to have similar patterns of failure and survival after treatment with SBRT, however there may be an increased risk of distant metastases with BAC. RTOG guideline-based target delineation provides encouraging local control rates for patients with BAC.

  2. Radiative heat transfer between metallic nanoparticles

    CERN Document Server

    Chapuis, Pierre-Olivier; Volz, Sebastian; Greffet, Jean-Jacques

    2008-01-01

    In this letter, we study the radiative heat transfer between two nanoparticles in the near field and in the far field. We find that the heat transfer is dominated by the electric dipole-dipole interaction for dielectric particles and by the magnetic dipole-dipole interaction for metallic nanoparticles. We introduce polarizabilities formulas valid for arbitrary values of the skin depth. While the heat transfer mechanism is different for metallic and dielectric nanoparticles, we show that the distance dependence is the same. However, the dependence of the heat flux on the particle radius is different.

  3. Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow base line and suppressor nozzles. Summary report. [conducted in the Boeing large anechoic test chamber and the NASA-Ames 40by 80-foot wind tunnel

    Science.gov (United States)

    Jaeck, C. L.

    1977-01-01

    A test program was conducted in the Boeing large anechoic test chamber and the NASA-Ames 40- by 80-foot wind tunnel to study the near- and far-field jet noise characteristics of six baseline and suppressor nozzles. Static and wind-on noise source locations were determined. A technique for extrapolating near field jet noise measurements into the far field was established. It was determined if flight effects measured in the near field are the same as those in the far field. The flight effects on the jet noise levels of the baseline and suppressor nozzles were determined. Test models included a 15.24-cm round convergent nozzle, an annular nozzle with and without ejector, a 20-lobe nozzle with and without ejector, and a 57-tube nozzle with lined ejector. The static free-field test in the anechoic chamber covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K. The wind tunnel flight effects test repeated these nozzle test conditions with ambient velocities of 0 to 92 m/s.

  4. Study of Far—Field Directivity Pattern for Linear Arrays

    Science.gov (United States)

    Ana-Maria, Chiselev; Luminita, Moraru; Laura, Onose

    2011-10-01

    A model to calculate directivity pattern in far field is developed in this paper. Based on this model, the three-dimensional beam pattern is introduced and analyzed in order to investigate geometric parameters of linear arrays and their influences on the directivity pattern. Simulations in azimuthal plane are made to highlight the influence of transducers parameters, including number of elements and inter-element spacing. It is true that these parameters are important factors that influence the directivity pattern and the appearance of side-lobes for linear arrays.

  5. Frequency-independent radiation modes of interior sound radiation: Experimental study and global active control

    Science.gov (United States)

    Hesse, C.; Papantoni, V.; Algermissen, S.; Monner, H. P.

    2017-08-01

    Active control of structural sound radiation is a promising technique to overcome the poor passive acoustic isolation performance of lightweight structures in the low-frequency region. Active structural acoustic control commonly aims at the suppression of the far-field radiated sound power. This paper is concerned with the active control of sound radiation into acoustic enclosures. Experimental results of a coupled rectangular plate-fluid system under stochastic excitation are presented. The amplitudes of the frequency-independent interior radiation modes are determined in real-time using a set of structural vibration sensors, for the purpose of estimating their contribution to the acoustic potential energy in the enclosure. This approach is validated by acoustic measurements inside the cavity. Utilizing a feedback control approach, a broadband reduction of the global acoustic response inside the enclosure is achieved.

  6. The mechanism of the effect of a plasma layer with negative permittivity on the antenna radiation field

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunsheng, E-mail: wangcs@hit.edu.cn; Liu, Hui; Jiang, Binhao [Harbin Institute of Technology, Mail Box 402, Harbin 150001 (China); Li, Xueai [Harbin Electric Machinery Company Limited, Harbin 150001 (China)

    2015-06-15

    A model of a plasma–antenna system is developed to study the mechanism of the effect of the plasma layer on antenna radiation. Results show a plasma layer with negative permittivity is inductive, and thus affects the phase difference between electric and magnetic fields. In the near field of antenna radiation, a plasma layer with proper parameters can compensate the capacitivity of the vacuum and enhance the radiation power. In the far field of antenna radiation, the plasma layer with negative permittivity increases the inductivity of the vacuum and reduces the radiation power.

  7. Recurrence Patterns and Second Primary Lung Cancers After Stereotactic Body Radiation Therapy for Early-Stage Non-Small-Cell Lung Cancer: Implications for Surveillance.

    Science.gov (United States)

    Spratt, Daniel E; Wu, Abraham J; Adeseye, Victoria; Din, Shaun U; Shaikh, Fauzia; Woo, Kaitlin M; Zhang, Zhigang; Foster, Amanda; Rosenzweig, Kenneth E; Gewanter, Richard; Huang, James; Rimner, Andreas

    2016-05-01

    Patients treated with stereotactic body radiation therapy (SBRT) for early-stage non-small-cell lung cancer (NSCLC) are subject to locoregional and distant recurrence, as well as the formation of second primary lung cancers (SPLCs). The optimal surveillance regimen for patients treated with SBRT for early-stage NSCLC remains unclear; we therefore investigated the posttreatment recurrence patterns and development of SPLCs. Three hundred sixty-six patients with pathologically proven inoperable early-stage NSCLC treated with SBRT between 2006 and 2013 were assessed. Patients underwent a computed tomographic (CT) scan of the chest every 3 months during years 1 and 2, every 6 months during years 3 and 4, and annually thereafter. Competing risk analysis was used for all time-to-event analyses. With a median follow-up of 23 months, the 2-year cumulative incidence of local, nodal, and distant treatment failures were 12.2%, 16.1%, and 15.5%, respectively. In patients with disease progression after SBRT (n = 108), 84% (n = 91) of cases occurred within the first 2 years. Five percent (n = 19) of patients experienced SPLCs. The median time to development of an SPLC was 16.5 months (range, 6.5-71.1 months), with 33% (n = 6) of these patients experiencing SPLCs after 2 years. None of the never smokers, but 4% of former tobacco smokers and 15% of current tobacco smokers, experienced an SPLC (P = .005). Close monitoring with routine CT scans within the first 2 years after SBRT is effective in detecting early disease progression. In contrast, the risk for the development of an SPLC remains elevated beyond 2 years, particularly in former and current smokers. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Long-Term Outcomes and Patterns of Relapse of Early-Stage Extranodal Marginal Zone Lymphoma Treated With Radiation Therapy With Curative Intent

    Energy Technology Data Exchange (ETDEWEB)

    Teckie, Sewit; Qi, Shunan; Lovie, Shona [Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York (United States); Navarrett, Scott [Weill Cornell Medical College, New York, New York (United States); Hsu, Meier [Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York (United States); Noy, Ariela; Portlock, Carol [Lymphoma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York (United States); Yahalom, Joachim, E-mail: yahalomj@mskcc.org [Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York (United States)

    2015-05-01

    Purpose: To report the long-term outcome and patterns of relapse of a large cohort of marginal zone lymphoma (MZL) patients treated with curative-intent radiation therapy (RT) alone. Patients and Methods: We reviewed the charts of 490 consecutive patients with stage IE or IIE MZL referred between 1992 and 2012 to our institution. Of those, 244 patients (50%) were treated with RT alone. Pathology was confirmed by hematopathologists at our institution. Patient and disease factors were analyzed for association with relapse-free survival (RFS) and overall survival (OS). Results: Median age of the cohort was 59 years, and median follow-up was 5.2 years. Ann Arbor stage was IE in 92%. Most common disease sites were stomach (50%), orbit (18%), non-thyroid head-and-neck (8%), skin (8%), and breast (5%). Median RT dose was 30 Gy. Five-year OS and RFS were 92% and 74%, respectively. Cumulative incidence of disease-specific death was just 1.1% by 5 years. Sixty patients (24%) developed relapse of disease; 10 were in the RT field. Crude rate of transformation to pathologically confirmed large-cell lymphoma was 1.6%. On multivariable analysis, primary disease site (P=.007) was independently associated with RFS, along with age (P=.04), presence of B-symptoms (P=.02), and International Prognostic Index risk group (P=.03). All disease sites except for head-and-neck had worse RFS relative to stomach. Conclusion: Overall and cause-specific survival are high in early-stage extra-nodal MZL treated with curative RT alone. In this large cohort of 244 patients, most patients did not experience relapse of MZL after curative RT; when relapses did occur, the majority were in distant sites. Stomach cases were less likely to relapse than other anatomic sites. Transformation to large-cell lymphoma was rare.

  9. Substrate specificity of glucose dehydrogenase and carbon source utilization pattern of pantoea dispersa strain P2 and its radiation induced mutants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Keun; Murugesan, Senthilkumar [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2009-06-15

    Mineral phosphate solubilizing pantoea dispersa strain P2 produced 5.5 mM and 42.6 mM of gluconic acid on 24 h and 72 h incubation, respectively. Strain P2 exhibited glucose dehydrogenase (GDH) specific activity of 0.32 IU mg{sup -1} protein. We have studied the substrate specificity of GDH as well as carbon source utilization pattern of strain P2. GDH of strain P2 did not use ribose as substrate. Utilization of lactose with specific activity of 0.65 IU mg{sup -1} protein indicated that the enzyme belongs to GDH type B isozyme. Arabinose, galactose, ribose, sucrose and xylose did not induce the synthesis of GDH enzyme while mannose induced the synthesis of GDH with highest specific activity of 0.58 IU mg{sup -1} protein. Through radiation mutagenesis, the substrate specificity of GDH was modified in order to utilize side range of sugars available in root exudates. Ribose, originally not a substrate for GDH of strain P2 was utilized as substrate by mutants P2-M5 with specific activity of 0.44 and 0.57 IU mg{sup -1} protein, respectively. Specific activity of GDH on the media containing lactose and galactose was also improved to 1.2 and 0.52 IU mg{sup -1} protein in P2-M5 and P2-M6 respectively. Based on the carbon source availability in root exudate, the mutants can be selected and utilized as efficient biofertilizer under P-deficient soil conditions.

  10. Spatial Coherence of Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, S; Coisson, R

    2003-10-30

    Synchrotron Radiation (SR) has been widely used since the 80's as a tool for many applications of UV, soft X rays and hard X rays in condensed matter physics, chemistry and biology. The evolution of SR sources towards higher brightness has led to the design of low-emittance electron storage rings (emittance is the product of beam size and divergence), and the development of special source magnetic structures, as undulators. This means that more and more photons are available on a narrow bandwidth and on a small collimated beam; in other words there is the possibility of getting a high power in a coherent beam. In most applications, a monochromator is used, and the temporal coherence of the light is given by the monochromator bandwidth. With smaller and smaller sources, even without the use of collimators, the spatial coherence of the light has become appreciable, first in the UV and soft X ray range, and then also with hard X rays. This has made possible new or improved experiments in interferometry, microscopy, holography, correlation spectroscopy, etc. In view of these recent possibilities and applications, it is useful to review some basic concepts about spatial coherence of SR, and its measurement and applications. In particular we show how the spatial coherence properties of the radiation in the far field can be calculated with simple operations from the single-electron amplitude and the electron beam angular and position spreads. The gaussian approximation will be studied in detail for a discussion of the properties of the far field mutual coherence and the estimate of the coherence widths, and the comparison with the VanCittert-Zernike limit.

  11. On the ability of RegCM4 to simulate surface solar radiation patterns over Europe: An assessment using satellite-based observations

    Science.gov (United States)

    Alexandri, Georgia; Georgoulias, Aristeidis K.; Zanis, Prodromos; Tsikerdekis, Athanasios; Katragkou, Eleni; Kourtidis, Konstantinos; Meleti, Charikleia

    2015-04-01

    We assess here the ability of RegCM4 to simulate the surface solar radiation (SSR) patterns over the European domain. For the needs of this work, a decadal (1999-2009) simulation was implemented at a horizontal resolution of 50km using the first year as a spin-up. The model is driven by emissions from CMIP5 while ERA-interim data were used as lateral boundary conditions. The RegCM4 SSR fields were validated against satellite-based SSR observations from Meteosat First Generation (MFG) and Meteosat Second Generation (MSG) sensors (CM SAF SIS product). The RegCM4 simulations slightly overestimate SSR compared to CM SAF over Europe with the bias being +1.54% in case of MFG (2000-2005) and +3.34% in case of MSG (2006-2009). SSR from RegCM4 is much closer to SSR from CM SAF over land (bias of -1.59% for MFG and +0.66% for MSG) than over ocean (bias of +7.20% for MFG and 8.07% for MSG). In order to understand the reasons of this bias, we proceeded to a detailed assessment of various parameters that define the SSR levels (cloud fractional cover - CFC, cloud optical thickness - COT, cloud droplet effective radius - Re, aerosol optical thickness - AOD, asymmetry factor - ASY, single scattering albedo - SSA, water vapor - WV and surface albedo - ALB). We validated the simulated CFC, COT and Re from RegCM4 against satellite-based observations from MSG and we found that RegCM4 significantly underestimates CFC and Re, and overestimates COT over Europe. The aerosol-related parameters from RegCM4 were compared with values from the aerosol climatology taken into account within CM SAF SSR estimates. AOD is significantly underestimated in our simulations which leads to a positive SSR bias. The RegCM4 WV and ALB were compared with WV values from ERA-interim and ALB climatological observations from CERES which are also taken into account within CM SAF SSR estimates. Finally, with the use of a radiative transfer model (SBDART) we manage to quantify the relative contribution of each of

  12. Identification of collapse patterns of cavitation bubbles close to a solid wall

    Directory of Open Access Journals (Sweden)

    Zima P.

    2013-04-01

    Full Text Available The article describes different patterns of bubble deformation during the cavitation bubble collapse close to a solid wall for different bubble-wall distances. The bubble is generated by energy discharge in water. The collapse patterns are investigated using high-speed photography. The magnitude of the bubble-wall interaction is measured using the PVDF film. The shock wave pressure in the far field is measured using the PVDF hydrophone.

  13. Vibration and acoustic radiation of a finite cylindrical shell submerged at finite depth from the free surface

    Science.gov (United States)

    Guo, Wenjie; Li, Tianyun; Zhu, Xiang; Miao, Yuyue; Zhang, Guanjun

    2017-04-01

    The far-field acoustic radiation of a cylindrical shell with finite length submerged at finite depth from the water surface is studied. Two steps are utilized to solve the problem. The first step is to determine the vibration response of the submerged cylindrical shell by using an analytical method and the second one is to determine the far field sound radiation with the boundary element method. To address the vibration responses of the shell analytically, the cylindrical shell and surrounding fluid are described by the Flügge shell equations and Laplace equation in the cylindrical coordinate system respectively. The free surface effect is taken into consideration by using the image method and the Graf's addition theorem. The reliability and efficiency of the present method are validated by comparison with the finite element method. Then, based on the vibration responses of the shell obtained from the first step, the far-field sound pressure is computed by using the boundary element method. It is found that the vibration of the cylindrical shell submerged at finite depth from the free surface tends to be the same as that in infinite fluid when the submerged depth exceeds a certain value. The frequency and the submerged depth have crucial effects on the fluctuation of the far-field sound pressure, while for the curve of sound pressure level versus immersion depth, the ratio of the distance between the adjacent peak points of sound pressure to the wavelength is independent of the frequency. Moreover, the petal number of the directivity of the far-field sound pressure increases with the increase of the frequency and the submerged depth. The work provides more understanding on the vibration and acoustic radiation behavior of a finite cylindrical shell submerged at finite depth.

  14. Gleason Pattern 5 Is the Greatest Risk Factor for Clinical Failure and Death From Prostate Cancer After Dose-Escalated Radiation Therapy and Hormonal Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Sabolch, Aaron [University of Michigan Medical School, Ann Arbor, MI (United States); Feng, Felix Y. [University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, Ann Arbor, MI (United States); Veterans Administration Medical Center, Ann Arbor, MI (United States); Daignault-Newton, Stephanie [University of Michigan Medical School, Ann Arbor, MI (United States); Division of Biostatistics, Ann Arbor, MI (United States); Halverson, Schuyler; Blas, Kevin; Phelps, Laura [University of Michigan Medical School, Ann Arbor, MI (United States); Olson, Karin B. [University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, Ann Arbor, MI (United States); Sandler, Howard M. [Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, CA (United States); Hamstra, Daniel A., E-mail: dhamm@med.umich.edu [Department of Radiation Oncology, Ann Arbor, MI (United States)

    2011-11-15

    Purpose: The division of Gleason score (GS) into three categories (2-6, 7, 8-10) may not fully use its prognostic power, as revealed by recent reports demonstrating the presence of Gleason Pattern 5 (GP5) as a strong predictor for biochemical recurrence. Therefore, we analyzed the clinical outcomes in patients treated with dose-escalated radiation therapy (RT) based on the presence or absence of GP5. Methods and Materials: Outcomes were analyzed for 718 men treated for localized prostate cancer with external-beam RT to a minimum planning target volume dose of at least 75 Gy. We assessed the impact of GP5 and that of pretreatment- and treatment-related factors on freedom from biochemical failure, freedom from metastasis (FFM), cause-specific survival (CSS), and overall survival (OS). Results: At biopsy, 89% of patients had no GP5, and 11% (76/718) had GP5. There were no differences in age, comorbid illness, T stage, prostate-specific antigen, or the use or duration of androgen deprivation therapy between GS8 without GP5 and GS8-10 with GP5. The presence of GP5 predicted lower FFM (p < 0.002; hazard ratio [HR] 3.4 [1.7-7.1]); CSS (p < 0.0001; HR 12.9 [5.4-31]); and OS (p < 0.0001; HR 3.6 [2.0-6.5]) in comparison with GS8 (without GP5). The 8-year FFM, CSS, and OS were 89%, 98%, and 57%, respectively, for those with Gleason 8 prostate cancer without GP5 in comparison with 61%, 55%, and 31%, respectively, for those with GP5. In addition, both FFM and CSS were strongly influenced by androgen deprivation therapy given concurrently with RT. On multivariate analysis, GP5 was the strongest prognostic factor for all clinical endpoints, including OS. Conclusion: The presence of GP5 predicts for worse clinical behavior, which therefore needs to be accounted for by risk stratification schemes. Further intensification of local and/or systemic therapy may be appropriate for such patients.

  15. The Performance Improvement of Indoor MIMO Systems with Reconfigurable Radiation Patterns%室内方向图可重构多天线系统的性能改善

    Institute of Scientific and Technical Information of China (English)

    王海涛; 宋荣方

    2011-01-01

    为了提高笔记本终端无线网络的性能,考虑采用方向图可重构多输入多输出天线(MIMO).由于室内周围人的移动对网络传输性能的影响,提出了基于可重构天线辐射状态的选择算法.它的基本原理是,可重构天线的辐射状态对应着信道的传播状态,选择最佳辐射状态对应着选择最佳信道传输状态,也就是最大化信道矩阵的Frobenius范数.理论研究及仿真结果表明,可重构MIMO系统相比传统MIMO可获得更多的阵列增益和遍历容量,并且随着每根天线的方向图数目的增多而增加.%In order to enhance the performance of wireless network of the notebook terminals,Multi-input Multi-output(MIMO) systems with reconfigurable radiation pattern is evaluated. Considering the influence of peoples' moving on the performance of the network transmission, we propose an antenna algorithm based on the state of radiation pattern of reconfigurable antennas. The algorithm is based on the fact that the radiation states of the reconfigurable antennas are corresponding to the channel states and optimizing radiation state is to maximize the Frobenius norm of the channel matrix. Theoretical research and simulation results show that, compared with the traditional MIMO system, reconfigurable MIMO system can obtain more array gain and ergodic capacity, which is directly proportional to the number of the radiation states of each antenna.

  16. Utilization of the integral equation method for determining the characteristic radiation features of antennas

    Science.gov (United States)

    Zink, M.

    The integral equation method in the form of the electric field integral equation for wire grid models provides the current distribution on the surface of structures under study. Characteristic parameters such as the input impedance and the radiation diagram are obtained in this fashion. These parameters are determined for a dipole in free space, a monopole over a circular ground plane, and a torus antenna. Good results are obtained for the far field and the variables related to it.

  17. Capturing atmospheric effects on 3D millimeter wave radar propagation patterns

    Science.gov (United States)

    Cook, Richard D.; Fiorino, Steven T.; Keefer, Kevin J.; Stringer, Jeremy

    2016-05-01

    Traditional radar propagation modeling is done using a path transmittance with little to no input for weather and atmospheric conditions. As radar advances into the millimeter wave (MMW) regime, atmospheric effects such as attenuation and refraction become more pronounced than at traditional radar wavelengths. The DoD High Energy Laser Joint Technology Offices High Energy Laser End-to-End Operational Simulation (HELEEOS) in combination with the Laser Environmental Effects Definition and Reference (LEEDR) code have shown great promise simulating atmospheric effects on laser propagation. Indeed, the LEEDR radiative transfer code has been validated in the UV through RF. Our research attempts to apply these models to characterize the far field radar pattern in three dimensions as a signal propagates from an antenna towards a point in space. Furthermore, we do so using realistic three dimensional atmospheric profiles. The results from these simulations are compared to those from traditional radar propagation software packages. In summary, a fast running method has been investigated which can be incorporated into computational models to enhance understanding and prediction of MMW propagation through various atmospheric and weather conditions.

  18. Antenna with Dielectric Having Geometric Patterns

    Science.gov (United States)

    Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)

    2013-01-01

    An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.

  19. 激光重频对脉冲非稳腔TEA CO2激光远场传输特性的影响分析%Analysis of far-field characteristics with repetition frequency of TEA CO2 laser

    Institute of Scientific and Technical Information of China (English)

    汤伟; 郭劲; 邵俊峰; 郭汝海; 王挺峰

    2013-01-01

    为了研究TEA CO2激光重复频率对远场光束特性的影响,首先采用有限元方法计算了不同重复频率下反射镜的温度场和热变形分布,然后采用协方差矩阵法对镜面热变形进行了Zernike拟合,最后结合衍射的角谱传播理论和功率谱反演法分析了不同重频TEA CO2激光经过内光路热畸变作用后的远场光束特性。研究表明:在净吸收能量相同的情况下,随着重复频率的增大,反射镜的温度逐渐升高,热变形量逐渐增大,经过内光路热畸变作用后,远场光束的Sr和平均能量密度Ed逐渐减小,参数逐渐增大,光束质量逐渐变差;对于TEA CO2激光,重频为300 Hz的Ed值仅为10 Hz的40%,远场光束的峰值光强下降了43%,光斑展宽了近60%。文中的研究结果为TEA CO2激光发射系统的优化设计提供可靠的依据。%In order to study the influence of TEA CO2 laser repetition frequency on far-field beam quality, the temperature field and thermal deformation distribution of the mirror were calculated firstly by the finite element analysis of thermodynamics instantaneous method with TEA CO2 laser irradiation of different repetition frequencies. Then, mirror thermal distortion was fitted by Zernike polynomials. Finally, far-field characteristics of different repetition frequencies TEA CO2 laser were obtained by the angular spectrum propagation theory of diffraction. The theory and simulation results show that with the increasing of laser repetition frequency, the mirror temperature and thermal deformation are gradually increasing. After thermal deformation effect, Sr and the average energy density Ed decrease, and parameter gradually increases in the far field. Comparing with 10 Hz, Ed of 300 Hz decreases 40%, peak power in the far field decreases 43% and beam waist broadens 60%. When the laser repetition frequency is greater than 100 Hz,due to the appearance of peaks and valleys on the mirror, the far-field

  20. Radiation from structured-ring resonators

    CERN Document Server

    Maling, B; Craster, R V

    2016-01-01

    We investigate the scalar-wave resonances of systems composed of identical Neumann-type inclusions arranged periodically around a circular ring. Drawing on natural similarities with the undamped Rayleigh-Bloch waves supported by infinite linear arrays, we deduce asymptotically the exponentially small radiative damping in the limit where the ring radius is large relative to the periodicity. In our asymptotic approach, locally linear Rayleigh-Bloch waves that attenuate exponentially away from the ring are matched to a ring-scale WKB-type wave field. The latter provides a descriptive physical picture of how the mode energy is transferred via tunnelling to a circular evanescent-to-propagating transition region a finite distance away from the ring, from where radiative grazing rays emanate to the far field. Excluding the zeroth-order standing-wave modes, the position of the transition circle bifurcates with respect to clockwise and anti-clockwise contributions, resulting in striking spiral wavefronts.