WorldWideScience

Sample records for aperture tabletop soft

  1. A table-top femtosecond time-resolved soft x-ray transient absorption spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Leone, Stephen; Loh, Zhi-Heng; Khalil, Munira; Correa, Raoul E.; Leone, Stephen R.

    2008-05-21

    A laser-based, table-top instrument is constructed to perform femtosecond soft x-ray transient absorption spectroscopy. Ultrashort soft x-ray pulses produced via high-order harmonic generation of the amplified output of a femtosecond Ti:sapphire laser system are used to probe atomic core-level transient absorptions in atoms and molecules. The results provide chemically specific, time-resolved dynamics with sub-50-fs time resolution. In this setup, high-order harmonics generated in a Ne-filled capillary waveguide are refocused by a gold-coated toroidal mirror into the sample gas cell, where the soft x-ray light intersects with an optical pump pulse. The transmitted high-order harmonics are spectrally dispersed with a home-built soft x-ray spectrometer, which consists of a gold-coated toroidal mirror, a uniform-line spaced plane grating, and a soft x-ray CCD camera. The optical layout of the instrument, design of the soft x-ray spectrometer, and spatial and temporal characterization of the high-order harmonics are described. Examples of static and time-resolved photoabsorption spectra collected on this apparatus are presented.

  2. Table-top water-window soft X-ray microscope using a Z-pinching capillary discharge source

    Science.gov (United States)

    Nawaz, M. F.; Nevrkla, M.; Jancarek, A.; Torrisi, A.; Parkman, T.; Turnova, J.; Stolcova, L.; Vrbova, M.; Limpouch, J.; Pina, L.; Wachulak, P.

    2016-07-01

    The development and demonstration of a table-top transmission soft X-ray (SXR) microscope, using a laboratory incoherent capillary discharge source has been carried out. This Z-pinching capillary discharge water-window SXR source, is a first of its kind to be used for high spatial resolution microscopy at λ = 2.88 nm (430 eV) . A grazing incidence ellipsoidal condenser mirror is used for focusing of the SXR radiation at the sample plane. The Fresnel zone plate objective lens is used for imaging of the sample onto a back-illuminated (BI) CCD camera. The achieved half-pitch spatial resolution of the microscope approaches 100 nm, as demonstrated by the knife-edge test. Details about the source, and the construction of the microscope are presented and discussed. Additionally, the SXR images of various samples, proving applicability of such microscope for observation of objects in the nanoscale, are shown.

  3. Energy extraction and achievement of the saturation limit in a discharge pumped table-top soft x-ray amplifier.

    Science.gov (United States)

    Rocca, J. J.; Clark, D. P.; Chilla, J. L. A.; Shlyaptsev, V. N.; Marconi, M. C.

    1996-11-01

    There is significant interest in the demonstration of compact soft x-ray amplifiers capable of generating pulses of substantial energy for applications. This motivates the demonstration of gain media generated by compact devices, that can be successfully scaled in length to reach gain saturation. To date, gain saturation had only been achieved in a few soft x-ray laser lines in plasmas generated by some of the world's largest laser facilities.(B. J. MacGowan et al.), Phys. Fluids B 4, 2326 (1992); A. Carillon et al., Phys. Rev. Lett 68, 2917 (1992);B. Rus et al., in AIP Conf. Proc. 332, X-ray lasers 1994, p. 152; S. Wang et al., ibid., p. 293. Previosly we reported large amplification at 46.9 nm in Ne-like argon in a plasma column generated by a fast capillary discharge.(J. J. Rocca et al.), Phys. Rev. Lett. 73, 2192 (1994). Herein we report the generation of laser pulse energies up to 30 μJ at 46.9 nm in such discharge and the first clear evidence of gain saturation of a table-top soft x-ray amplifier. Single pass amplification experiments yielded laser pulse energies up to 6 μJ and double pass amplification using an iridium mirror yielded 30 μJ. The observed saturation of the gain and laser pulse energy are in good agreement with the results of radiation transport calculations. Work supported by the National Science Foundation.

  4. “Water window” compact, table-top laser plasma soft X-ray sources based on a gas puff target

    Science.gov (United States)

    Wachulak, P. W.; Bartnik, A.; Fiedorowicz, H.; Rudawski, P.; Jarocki, R.; Kostecki, J.; Szczurek, M.

    2010-05-01

    We have developed compact, high repetition, table-top soft-X-ray sources, based on a gas puff target, emitting in "water window" spectral range at λ = 2.88 nm from nitrogen gas target or, in 2-4 nm range of wavelengths, from argon gas target. Double stream gas puff target was pumped optically by commercial Nd:YAG laser, energy 0.74 J, pulse time duration 4 ns. Spatial distribution of laser-produced plasma was imaged using a pinhole camera. Using transmission grating spectrometer, argon and nitrogen emission spectra were obtained, showing strong emission in the "water window" spectral range. Using AXUV100 detector the flux measurements of the soft-X-ray pulses were carried out and are presented. These debris free sources are table-top alternative for free electron lasers and synchrotron installations. They can be successfully employed in microscopy, spectroscopy and metrology experiments among others.

  5. Apertures

    CERN Document Server

    Hansen, R C

    2014-01-01

    Microwave Scanning Antennas, Volume I: Apertures is a comprehensive account of phased arrays, multiple beam arrays, time domain and synthetic apertures, and adaptive antennas. Advances in continuous apertures and near field theory are discussed. Low noise and monopulse apertures, optical scanners, and large radomes are also covered, along with radio astronomy instruments and associated theory.Comprised of five chapters, this volume begins with an overview of aperture theory as well as aperture distributions and near field theory. The second and third chapters deal with mechanically steered and

  6. Multi-mJ mid-infrared kHz OPCPA and Yb-doped pump lasers for tabletop coherent soft x-ray generation

    International Nuclear Information System (INIS)

    We present our recent progress on the development of a mid-infrared (mid-IR), multi-mJ, kHz optical parametric chirped-pulse amplification (OPCPA) system, pumped by a homebuilt picosecond cryogenic Yb:YAG chirped-pulse amplifier, and its application to soft x-ray high-order harmonic generation. The cryogenic Yb:YAG laser operating at 1 kHz repetition rate delivers 42 mJ, 17 ps, 1.03 μm pulses to pump the OPCPA system. Efficient second and fourth harmonic generations from the Yb:YAG system are demonstrated, which provide the pumping capability for OPCPA at various wavelengths. The mid-IR OPCPA system produces 2.6 mJ, 39 fs, 2.1 μm pulses with good beam quality (M 2 = ∼1.5) at 1 kHz repetition rate. The output pulses of the OPCPA are used to generate high-order harmonics in both gas cell and hollow-core fiber targets. A photon flux of ∼2 × 108 photon/s/1% bandwidth at 160 eV in Ar is measured while the cutoff is 190 eV. The direct measurements of the photon flux from x-ray photodiodes have confirmed the generation of water-window soft x-ray photons with a flux ∼106 photon/s/1% bandwidth at 330 eV in Ne. The demonstrated OPCPA and Yb:YAG pump laser technologies provide an excellent platform of energy and power scalable few-cycle mid-IR sources that are suitable for high-flux tabletop coherent soft x-ray generation. (paper)

  7. Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by nanosecond pulse of soft X-ray source and/or UV laser

    International Nuclear Information System (INIS)

    The practical applicability of the rare-earth doped scintillators in high-speed detectors is limited by the slow decay components in the temporal response of a scintillator. The study of origin and properties of material defects that induce the slow decay components is of major importance for the development of new scintillation materials. We present a table-top, time-domain UV-VIS luminescence spectrometer, featuring extended time and input sensitivity ranges and two excitation sources. The combination of both soft X-ray/XUV and UV excitation source allows the comparative measurements of luminescence spectra and decay kinetics of scintillators to be performed under the same experimental conditions. The luminescence of emission centers of a doped scintillator can be induced by conventional N2 laser pulse, while the complete scintillation process can be initiated by a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of 4 ns duration. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu3Al5O12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of the doped Ce3+ ions was studied under 2.88 nm (430 eV) XUV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3.68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d2 transition of Ce3+ is directly excited. Furthermore, YAG:Ce and LuAG:Ce single crystals luminescence decay profiles are compared and discussed.

  8. Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by nanosecond pulse of soft X-ray source and/or UV laser

    Energy Technology Data Exchange (ETDEWEB)

    Bruza, Petr; Fidler, Vlastimil [Faculty of Biomedical Engineering, Czech Technical University, Nam. Sitna 3105, Kladno (Czech Republic); Nikl, Martin, E-mail: petr.bruza@fbmi.cvut.cz [Institute of Physics, Academy of Sciences of The Czech Republic, Cukrovarnicka 10, Prague (Czech Republic)

    2011-09-15

    The practical applicability of the rare-earth doped scintillators in high-speed detectors is limited by the slow decay components in the temporal response of a scintillator. The study of origin and properties of material defects that induce the slow decay components is of major importance for the development of new scintillation materials. We present a table-top, time-domain UV-VIS luminescence spectrometer, featuring extended time and input sensitivity ranges and two excitation sources. The combination of both soft X-ray/XUV and UV excitation source allows the comparative measurements of luminescence spectra and decay kinetics of scintillators to be performed under the same experimental conditions. The luminescence of emission centers of a doped scintillator can be induced by conventional N{sub 2} laser pulse, while the complete scintillation process can be initiated by a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of 4 ns duration. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu{sub 3}Al{sub 5}O{sub 12} single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of the doped Ce{sup 3+} ions was studied under 2.88 nm (430 eV) XUV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3.68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d{sub 2} transition of Ce{sup 3+} is directly excited. Furthermore, YAG:Ce and LuAG:Ce single crystals luminescence decay profiles are compared and discussed.

  9. Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by nanosecond pulse of soft X-ray source and/or UV laser

    Science.gov (United States)

    Brůža, Petr; Fidler, Vlastimil; Nikl, Martin

    2011-09-01

    The practical applicability of the rare-earth doped scintillators in high-speed detectors is limited by the slow decay components in the temporal response of a scintillator. The study of origin and properties of material defects that induce the slow decay components is of major importance for the development of new scintillation materials. We present a table-top, time-domain UV-VIS luminescence spectrometer, featuring extended time and input sensitivity ranges and two excitation sources. The combination of both soft X-ray/XUV and UV excitation source allows the comparative measurements of luminescence spectra and decay kinetics of scintillators to be performed under the same experimental conditions. The luminescence of emission centers of a doped scintillator can be induced by conventional N2 laser pulse, while the complete scintillation process can be initiated by a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of 4 ns duration. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu3Al5O12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of the doped Ce3+ ions was studied under 2.88 nm (430 eV) XUV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3.68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d2 transition of Ce3+ is directly excited. Furthermore, YAG:Ce and LuAG:Ce single crystals luminescence decay profiles are compared and discussed.

  10. Interactive tabletops in education

    OpenAIRE

    Dillenbourg, Pierre; Evans, Michael

    2011-01-01

    Interactive tabletops are gaining increased attention from CSCL researchers. This paper analyses the relation between this technology and teaching and learning processes. At a global level, one could argue that tabletops convey a socio-constructivist flavor: they support small teams that solve problems by exploring multiple solutions. The development of tabletop applications also witnesses the growing importance of face-to-face collaboration in CSCL and acknowledges the physicality of learnin...

  11. Interactive Tabletops in Education

    Science.gov (United States)

    Dillenbourg, Pierre; Evans, Michael

    2011-01-01

    Interactive tabletops are gaining increased attention from CSCL researchers. This paper analyses the relation between this technology and teaching and learning processes. At a global level, one could argue that tabletops convey a socio-constructivist flavor: they support small teams that solve problems by exploring multiple solutions. The…

  12. A comparative study on dual colour soft aperture cascaded second-order mode-locking with different nonlinear optical crystals

    Indian Academy of Sciences (India)

    Shyamal Mondal; Satya Pratap Singh; Sourabh Mukhopadhyay; Aditya Date; Kamal Hussain; Shouvik Mukherjee; Prasanta Kumar Datta

    2014-02-01

    A comparative study in terms of optimized output power and stability is made on cascaded second-order nonlinear optical mode-locking with KTP, BBO and LBO crystals for both 1064 nm and 532 nm. Large nonlinear optical phase shift achieved in a non-phase-matched second harmonic generating crystal, is transformed into amplitude modulation through soft aperturing the nonlinear cavity mode variation at the laser gain medium to mode-lock a Nd:YVO4 laser. The laser delivers stable dual wavelength cw mode-locked pulse train with pulse duration 10.3 ps and average power of 1.84 W and 255 mW at 1064 nm and 532 nm respectively for the optimum performance in type-II KTP crystal. The exceptional stability achieved with KTP is accounted by simulating the mode-size variation with phase mismatch.

  13. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    KAUST Repository

    Sibillano, T.

    2014-11-10

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes\\' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  14. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    Science.gov (United States)

    Sibillano, T.; de Caro, L.; Altamura, D.; Siliqi, D.; Ramella, M.; Boccafoschi, F.; Ciasca, G.; Campi, G.; Tirinato, L.; di Fabrizio, E.; Giannini, C.

    2014-11-01

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  15. Tracing coffee tabletop traces.

    Science.gov (United States)

    Leiterer, Jork; Emmerling, Franziska; Panne, Ulrich; Christen, Wolfgang; Rademann, Klaus

    2008-08-01

    Crystallization processes under different conditions are of fundamental interest in chemistry, pharmacy, and medicine. Therefore, we have studied the formation of micro- and nanosized crystals using water-caffeine (1,3,7-trimethyl-1 H-purine-2,6(3 H,7 H)-dione) solutions under ambient conditions as a relevant model system. When droplets of an aqueous caffeine solution evaporate and eventually dry on surfaces (glass, polystyrene, and polyester), stable "coffee tabletop" rings with a perimeter of typically 3 mm are formed after 20 to 50 min. Using a micro focus X-ray beam available at the BESSY muSpot-beamline, the fine structure of different caffeine needles can be distinguished. Unexpectedly, both crystal modifications (alpha- and beta-caffeine) are present, but locally separated in these rings. Furthermore, AFM studies reveal the presence of even smaller particles on a nanometer length scale. To eliminate influences of surface irregularities from the crystallization process, acoustic levitation of liquid samples was employed. Such levitated droplets are trapped in a stable position and only surrounded by air. The solvent in an ultrasonically levitated drop evaporates completely, and the resulting crystallization of caffeine was followed in situ by synchrotron X-ray diffraction. In this case, the diffraction pattern is in accordance with pure alpha-caffeine and does not indicate the formation of the room temperature polymorph beta-caffeine. Hence, our investigations open new vistas that may lead to a controlled formation of cocrystals and novel polymorphs of micro- and nanocrystalline materials, which are of relevance for fundamental studies as well as for pharmaceutical and medical applications. PMID:18582001

  16. High Speed and High Resolution Table-Top Nanoscale Imaging

    CERN Document Server

    Tadesse, G K; Demmler, S; HÄdrich, S; Wahyutama, I; Steinert, M; Spielmann, C; ZÜrch, M; TÜnnermann, A; Limpert, J; Rothhardt, J

    2016-01-01

    We present a table-top coherent diffraction imaging (CDI) experiment based on high-order harmonics generated at 18 nm by a high average power femtosecond fiber laser system. The high photon flux, narrow spectral bandwidth and high degree of spatial coherence allow for ultra-high sub-wavelength resolution imaging at a high numerical aperture. Our experiments demonstrate a half-pitch resolution of 13.6 nm, very close to the actual Abbe-limit of 12.4 nm, which is the highest resolution achieved from any table-top XUV or X-ray microscope. In addition, 20.5 nm resolution was achieved with only 3 sec of integration time bringing live diffraction imaging and 3D tomography on the nanoscale one step closer to reality. The current resolution is solely limited by the wavelength and the detector size. Thus, table-top nanoscopes with only a few-nm resolutions are in reach and will find applications in many areas of science and technology.

  17. Table-top job analysis

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-01

    The purpose of this Handbook is to establish general training program guidelines for training personnel in developing training for operation, maintenance, and technical support personnel at Department of Energy (DOE) nuclear facilities. TTJA is not the only method of job analysis; however, when conducted properly TTJA can be cost effective, efficient, and self-validating, and represents an effective method of defining job requirements. The table-top job analysis is suggested in the DOE Training Accreditation Program manuals as an acceptable alternative to traditional methods of analyzing job requirements. DOE 5480-20A strongly endorses and recommends it as the preferred method for analyzing jobs for positions addressed by the Order.

  18. Dynamic tabletop interfaces for increasing creativity

    OpenAIRE

    SCHMITT, Lara; Buisine, Stéphanie; Chaboissier, Jonathan; AOUSSAT, Améziane; Vernier, Frédéric

    2012-01-01

    International audience We designed a tabletop brainwriting interface to examine the effects of time pressure and social pressure on the creative performance. After positioning this study with regard to creativity research and human activity in dynamic environments, we present our interface and experiment. Thirty-two participants collaborated (by groups of four) on the tabletop brainwriting task under four conditions of time pressure and two conditions of social pressure. The results show t...

  19. How do interactive tabletop systems influence collaboration?

    OpenAIRE

    Buisine, Stéphanie; Besacier, Guillaume; AOUSSAT, Améziane; Vernier, Frédéric

    2012-01-01

    This paper examines some aspects of the usefulness of interactive tabletop systems, if and how these impact collaboration. We chose creative problem solving such as brainstorming as an application framework to test several collaborative media: the use of pen-and-paper tools, the ‘‘around-the-table’’ form factor, the digital tabletop interface, the attractiveness of interaction styles. Eighty subjects in total (20 groups of four members) participated in the experiments. The evaluation criteria...

  20. RFIDice - Augmenting Tabletop Dice with RFID

    Directory of Open Access Journals (Sweden)

    Marc Langheinrich

    2008-08-01

    Full Text Available Augmented dice allow players of tabletop games to have the result of a roll be automatically recorded by a computer, e.g., for supporting strategy games. We have built a set of three augmented-dice-prototypes based on radio frequency identification (RFID technology, which allows us to build robust, cheap, and small augmented dice. Using a corresponding readout infrastructure and a sample application, we have evaluated our approach and show its advantages over other dice augmentation methods discussed in the literature.

  1. Softly, Softly

    Science.gov (United States)

    Diamond, Abigail

    2008-01-01

    The term "soft skills" encompasses a cluster of personality traits, language abilities, personal habits and, ultimately, values and attitudes. Soft skills complement "harder", more technical, skills, such as being able to read or type a letter, but they also have a significant impact on the ability of people to do their jobs and on their…

  2. Saturated output tabletop X-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, J.; Osterheld, A.L.; Nilsen, J.; Hunter, J.R. [Lawrence Livermore National Lab., CA (United States); Yuelin Li [Lawrence Livermore National Lab., CA (United States); ILSA, Lawrence Livermore National Lab., Livermore, CA (United States); Faenov, A.Ya.; Pikuz, T.A. [Lawrence Livermore National Lab., CA (United States); MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Shlyaptsev, V.N. [Lawrence Livermore National Lab., CA (United States); DAS, Univ. of California Davis-Livermore, Livermore, CA (United States)

    2001-07-01

    The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion X-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (compact multipulse terawatt) laser system at the Lawrence livermore national laboratory (LLNL) have produced several X-ray lasers operating in the saturation regime. Output energy of 10-15 {mu}J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d{yields}4p transition at 147 A with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the X-ray laser output. (orig.)

  3. Saturated output tabletop x-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, J; Osterheld, A L; Nilsen, J; Hunter, J R; Li, Y; Faenov, A Ya; Pikuz, T A; Shlyaptsev, N

    2000-12-01

    The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion x-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (Compact Multipulse Terawatt) laser system at the Lawrence Livermore National Laboratory (LLNL) have produced several x-ray lasers operating in the saturation regime. Output energy of 10-15 {micro}J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d {yields} 4p transition at 147 {angstrom} with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the x-ray laser output.

  4. Tabletop synchrotron and its unique features

    CERN Document Server

    Yamada, H

    2002-01-01

    Two synchrotrons, AURORA and MIRRORCLE, were built in Ritsumeikan University. MIRRORCLE-20 is the smallest normal conduction synchrotron (15 cm orbit radius and 1.2 m outer diameter) in the world. It uses 2/3 resonance method for electron beam incidence but is not optimized for X-ray generation. MIRRORCLE-6 shall be optimized for X-ray generation. X-ray generated by MIRRORCLE shows very flat white light, rich in hard X-ray, pulse with width changeable from a few mu s to a few ms , wide radiation angle of 25 mrad at MIRRORCLE-20 and 80 mrad at MIRRORCLE-8 and high coherence. The feature such as pulsed light and high coherence is expected to new application which photon radiation cannot practice. Imaging experiments by MIRRORCLE were carried out by Cu plate, Al plate, Teflon and acryl plate. We took a photograph of insect, electric lamp, connector, and cyclotron. New X-ray generation mechanism, X-ray strength, development of tabletop synchrotron and features of X-ray beam are explained. (S.Y.)

  5. Co-located collaborative visual analytics around a tabletop display.

    Science.gov (United States)

    Isenberg, Petra; Fisher, Danyel; Paul, Sharoda A; Morris, Meredith Ringel; Inkpen, Kori; Czerwinski, Mary

    2012-05-01

    Co-located collaboration can be extremely valuable during complex visual analytics tasks. We present an exploratory study of a system designed to support collaborative visual analysis tasks on a digital tabletop display. Fifteen participant pairs employed Cambiera, a visual analytics system, to solve a problem involving 240 digital documents. Our analysis, supported by observations, system logs, questionnaires, and interview data, explores how pairs approached the problem around the table. We contribute a unique, rich understanding of how users worked together around the table and identify eight types of collaboration styles that can be used to identify how closely people work together while problem solving. We show how the closeness of teams’ collaboration and communication influenced how they performed on the task overall. We further discuss the role of the tabletop for visual analytics tasks and derive design implications for future co-located collaborative tabletop problem solving systems.

  6. Fission of actinides using a table-top laser

    CERN Document Server

    Schwoerer, H; Sauerbrey, R; Galy, J; Magill, J; Rondinella, V; Schenkel, R; Butz, T

    2003-01-01

    Powerful table-top lasers are now available in the laboratory and can be used to induce nuclear reactions. We report the first demonstration of nuclear fission using a high repetition rate table-top laser with intensities of 10 sup 2 sup 0 W/cm sup 2. Actinide photo-fission has been achieved in both sup 2 sup 3 sup 8 U and sup 2 sup 3 sup 2 Th from the high-energy Bremsstrahlung radiation produced by laser acceleration of electrons. The fission products were identified by time-resolved gamma-spectroscopy. (authors)

  7. An Evaluation of Interactive Tabletops in Elementary Mathematics Education

    Science.gov (United States)

    Jackson, Alexander T.; Brummel, Bradley J.; Pollet, Cody L.; Greer, David D.

    2013-01-01

    This research examined the effect that a relatively new Computer Supported Collaborative Learning (CSCL) device, specifically an interactive tabletop, has on elementary students' attitudes toward collaborative technologies, mathematical achievement, and the gender gap in mathematics. Prior research has shown many positive effects of CSCL…

  8. Saturated tabletop x-ray laser system at 19 nm

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuelin [Institute of Laser Science and Applications, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Dunn, James [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Nilsen, Joseph [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Barbee, Troy W. Jr. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Osterheld, Albert L. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Shlyaptsev, Vyacheslav N. [Department of Applied Science, University of California at Davis-Livermore, Livermore, California 94550 (United States)

    2000-06-01

    Saturated operation of a tabletop x-ray laser at 19 nm is demonstrated with a laser-irradiated Mo slab target. The output energy, the intensity, the near-field beam pattern, and the beam divergence are characterized. The wavelength scalability and the high brightness make it a potential tool for x-ray laser applications. (c) 2000 Optical Society of America.

  9. Is a tabletop search for Planck scale signals feasible

    CERN Document Server

    Bekenstein, Jacob D

    2012-01-01

    Quantum gravity theory is untested experimentally. Could it be tested with tabletop experiments? While the common feeling is pessimistic, a detailed inquiry shows it possible to sidestep the onerous requirement of localization of a probe on Planck length scale. I suggest a tabletop experiment which, given state of the art ultrahigh vacuum and cryogenic technology, could already be sensitive enough to detect Planck scale signals. The experiment combines a single photon's degree of freedom with one of a macroscopic probe to test Wheeler's conception of "spacetime foam", the assertion that on length scales of the order Planck's, spacetime is no longer a smooth manifold. The scheme makes few assumptions beyond energy and momentum conservations, and is not based on a specific quantum gravity scheme.

  10. Evaluating heuristics for tabletop user segmentation based on simultaneous interaction

    OpenAIRE

    García Sanjuan, Fernando; Jaén Martínez, Francisco Javier; Catalá Bolós, Alejandro

    2013-01-01

    Differentiating between users that interact on a tabletop could be beneficial for collaborative tasks to support territoriality-oriented features such as a more efficient space management or a better presentation of the contents. In this paper, we design a novel algorithm for the user differentiation or segmentation based on the simultaneous manipulation of the controls. This is a potential differentiating factor that has remained unexplored so far, and in combination with other factors may b...

  11. Computer-supported creativity: Evaluation of a tabletop mind-map application

    OpenAIRE

    Buisine, Stéphanie; BESACIER, Guillaume; NAJM, Marianne; AOUSSAT, Améziane; Vernier, Frédéric

    2007-01-01

    International audience The aim of this study is to investigate the usability and usefulness of interactive tabletop technologies to support group creativity. We implemented a tabletop interface enabling groups of 4 participants to build mind-maps (a tool for associative thinking). With 24 users in a within-group design, we compared its use to traditional paper-and-pencil mind-mapping sessions. The results showed no difference in idea production, but the tabletop condition significantly imp...

  12. Exploring Whole-Hand Gestures in a Tabletop Environment for Urban Modeling

    OpenAIRE

    VANDOREN, Peter; Frederix, Karel; Coninx, Karin; VAN REETH, Frank

    2011-01-01

    Touch-based tabletop interaction with virtual environments (VEs) is a recent research interest. In particular, 3D navigation and object interaction on tabletops pose considerable research challenges given the flat, rectangular, two-dimensional workspace of an interactive tabletop. This paper explores the design of whole-hand gestures for urban modelling on an interactive, tilted tabletopsytem. These touch-based gestures fit a hybrid 2D/3D approach for navigation and object interaction in urba...

  13. Aperture optical antennas

    CERN Document Server

    Wenger, Jerome

    2014-01-01

    This contribution reviews the studies on subwavelength aperture antennas in the optical regime, paying attention to both the fundamental investigations and the applications. Section 2 reports on the enhancement of light-matter interaction using three main types of aperture antennas: single subwavelength aperture, single aperture surrounded by shallow surface corrugations, and subwavelength aperture arrays. A large fraction of nanoaperture applications is devoted to the field of biophotonics to improve molecular sensing, which are reviewed in Section 3. Lastly, the applications towards nano-optics (sources, detectors and filters) are discussed in Section 4.

  14. Guidance for a large tabletop exercise for a nuclear power plant

    International Nuclear Information System (INIS)

    Tabletop exercises are held to discuss issues related to the response of organizations to an emergency event. This document describes in task format the planning, conduct, and reporting of lessons learned for a large interagency tabletop. A sample scenario, focus areas, and discussion questions based on a simulated accident at a commercial nuclear power plant are provided

  15. Synchronization and Latency-Effects in Distributed Multi-Touch Tabletops in a Collaborative Environment

    NARCIS (Netherlands)

    Kleinrouweler, J.W.M.

    2013-01-01

    Multi-touch tabletops are convenient devices for co-located collaboration. However, there exist scenarios where not all participants are in the same physical location. To be able to collaborate using multi-touch tabletops in a remote setting we introduce the concept of distributed multi-touch tablet

  16. Face detection for interactive tabletop viewscreen system using olfactory display

    Science.gov (United States)

    Sakamoto, Kunio; Kanazawa, Fumihiro

    2009-10-01

    An olfactory display is a device that delivers smells to the nose. It provides us with special effects, for example to emit smell as if you were there or to give a trigger for reminding us of memories. The authors have developed a tabletop display system connected with the olfactory display. For delivering a flavor to user's nose, the system needs to recognition and measure positions of user's face and nose. In this paper, the authors describe an olfactory display which enables to detect the nose position for an effective delivery.

  17. Variable-aperture screen

    Science.gov (United States)

    Savage, George M.

    1991-01-01

    Apparatus for separating material into first and second portions according to size including a plurality of shafts, a plurality of spaced disks radiating outwardly from each of the shafts to define apertures and linkage interconnecting the shafts for moving the shafts toward or away from one another to vary the size of the apertures while the apparatus is performing the separating function.

  18. Mastering Apple Aperture

    CERN Document Server

    Fitzgerald, Thomas

    2013-01-01

    Written in a conversational style, the author will share his knowledge on advanced Aperture topics with detailed discussions of advanced topics, the theory behind some of those topics and lots of hints and tips for ways to improve your workflow.Photographer's who have a basic understanding of Aperture

  19. Rotating Aperture System

    Science.gov (United States)

    Rusnak, Brian; Hall, James M.; Shen, Stewart; Wood, Richard L.

    2005-01-18

    A rotating aperture system includes a low-pressure vacuum pumping stage with apertures for passage of a deuterium beam. A stator assembly includes holes for passage of the beam. The rotor assembly includes a shaft connected to a deuterium gas cell or a crossflow venturi that has a single aperture on each side that together align with holes every rotation. The rotating apertures are synchronized with the firing of the deuterium beam such that the beam fires through a clear aperture and passes into the Xe gas beam stop. Portions of the rotor are lapped into the stator to improve the sealing surfaces, to prevent rapid escape of the deuterium gas from the gas cell.

  20. Note: A table-top blast driven shock tube

    Science.gov (United States)

    Courtney, Michael W.; Courtney, Amy C.

    2010-12-01

    The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer that explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

  1. A Table-top Blast Driven Shock Tube

    CERN Document Server

    Courtney, Michael; 10.1063/1.3518970

    2011-01-01

    The prevalence of blast-induced traumatic brain injury in conflicts in Iraq and Afghanistan has motivated laboratory scale experiments on biomedical effects of blast waves and studies of blast wave transmission properties of various materials in hopes of improving armor design to mitigate these injuries. This paper describes the design and performance of a table-top shock tube that is more convenient and widely accessible than traditional compression driven and blast driven shock tubes. The design is simple: it is an explosive driven shock tube employing a rifle primer which explodes when impacted by the firing pin. The firearm barrel acts as the shock tube, and the shock wave emerges from the muzzle. The small size of this shock tube can facilitate localized application of a blast wave to a subject, tissue, or material under test.

  2. Analysis of the Argonne distance tabletop exercise method.

    Energy Technology Data Exchange (ETDEWEB)

    Tanzman, E. A.; Nieves, L. A.; Decision and Information Sciences

    2008-02-14

    The purpose of this report is to summarize and evaluate the Argonne Distance Tabletop Exercise (DISTEX) method. DISTEX is intended to facilitate multi-organization, multi-objective tabletop emergency response exercises that permit players to participate from their own facility's incident command center. This report is based on experience during its first use during the FluNami 2007 exercise, which took place from September 19-October 17, 2007. FluNami 2007 exercised the response of local public health officials and hospitals to a hypothetical pandemic flu outbreak. The underlying purpose of the DISTEX method is to make tabletop exercising more effective and more convenient for playing organizations. It combines elements of traditional tabletop exercising, such as scenario discussions and scenario injects, with distance learning technologies. This distance-learning approach also allows playing organizations to include a broader range of staff in the exercise. An average of 81.25 persons participated in each weekly webcast session from all playing organizations combined. The DISTEX method required development of several components. The exercise objectives were based on the U.S. Department of Homeland Security's Target Capabilities List. The ten playing organizations included four public health departments and six hospitals in the Chicago area. An extent-of-play agreement identified the objectives applicable to each organization. A scenario was developed to drive the exercise over its five-week life. Weekly problem-solving task sets were designed to address objectives that could not be addressed fully during webcast sessions, as well as to involve additional playing organization staff. Injects were developed to drive play between webcast sessions, and, in some cases, featured mock media stories based in part on player actions as identified from the problem-solving tasks. The weekly 90-minute webcast sessions were discussions among the playing organizations

  3. Tabletop imaging of structural evolutions in chemical reactions

    CERN Document Server

    Ibrahim, Heide; Beaulieu, Samuel; Schmidt, Bruno E; Thiré, Nicolas; Bisson, Éric; Hebeisen, Christoph T; Wanie, Vincent; Giguére, Mathieu; Kieffer, Jean-Claude; Sanderson, Joseph; Schuurman, Michael S; Légaré, François

    2014-01-01

    The introduction of femto-chemistry has made it a primary goal to follow the nuclear and electronic evolution of a molecule in time and space as it undergoes a chemical reaction. Using Coulomb Explosion Imaging we have shot the first high-resolution molecular movie of a to and fro isomerization process in the acetylene cation. So far, this kind of phenomenon could only be observed using VUV light from a Free Electron Laser [Phys. Rev. Lett. 105, 263002 (2010)]. Here we show that 266 nm ultrashort laser pulses are capable of initiating rich dynamics through multiphoton ionization. With our generally applicable tabletop approach that can be used for other small organic molecules, we have investigated two basic chemical reactions simultaneously: proton migration and C=C bond-breaking, triggered by multiphoton ionization. The experimental results are in excellent agreement with the timescales and relaxation pathways predicted by new and definitively quantitative ab initio trajectory simulations.

  4. Promoting community preparedness: lessons learned from the implementation of a chemical disaster tabletop exercise.

    Science.gov (United States)

    High, Erika H; Lovelace, Kay A; Gansneder, Bruce M; Strack, Robert W; Callahan, Barbara; Benson, Phillip

    2010-05-01

    Health educators are frequently called on to facilitate community preparedness planning. One planning tool is community-wide tabletop exercises. Tabletop exercises can improve the preparedness of public health system agencies to address disaster by bringing together individuals representing organizations with different roles and perspectives in specific disasters. Thus, they have the opportunity to identify each other's roles, capabilities, and limitations and to problem-solve about how to address the gaps and overlaps in a low-threat collaborative setting. In 2005, the North Carolina Office of Public Health Preparedness and Response developed a series of exercises to test the preparedness for chemical disasters in a metropolitan region in the southeastern United States. A tabletop exercise allowed agency heads to meet in an environment promoting inter- and intraagency public-private coordination and cooperation. The evaluation results reported here suggest ways in which any tabletop exercise can be enhanced through recruitment, planning, and implementation.

  5. Quick-Glance and In-Depth exploration of a tabletop map for visually impaired people

    OpenAIRE

    Bardot, Sandra; Brock, Anke; Serrano, Marcos; Jouffrais, Christophe

    2014-01-01

    National audience Interactive tactile maps provide visually impaired people with accessible geographic information. However, when these maps are presented on large tabletops, tactile exploration without sight is long and tedious due to the size of the surface. In this paper we present a novel approach to speed up the process of exploring tabletop maps in the absence of vision. Our approach mimics the visual processing of a map and consists in two steps. First, the Quick-Glance step allows ...

  6. APT: Aperture Photometry Tool

    Science.gov (United States)

    Laher, Russ

    2012-08-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  7. Assessment of the influence of a carbon fiber tabletop on portal imaging

    Science.gov (United States)

    Misiarz, Agnieszka; Krawczyk, Paweł; Swat, Kaja; Andrasiak, Michał

    2013-06-01

    The purpose of this paper was to investigate beam attenuation caused by a carbon-fiber tabletop and its influence on portal image quality. The dose was measured by a Farmer type jonization chamber. The measurements of the portal image quality were performed with an EPID QC phantom for 6 MV beam for a specified field size (covering all test elements of the phantom completely -26×26 cm2 in the isocenter, SSD 96.2 cm) and various portal—isocenter distances. The beam attenuation factor was measured for Polkam 16 treatment table with a carbon fiber tabletop. Carbon fiber tabletop induces beam attenuation in vertical direction by a factor of 3.39%. The lowest maximum deviation to the regression line for linearity was measured for 40 cm portal—phantom distance. The lowest signal to noise ratio was observed for the portal—phantom distance of 30 cm. This factor dropped by 9% for images with a tabletop. The difference in high contrast: horizontal is 3.64; 0.32; 3.25 for 50 cm, 40 cm and 30 cm respectively and vertical—3.64%; 0.32%; 4.01% for 50 cm, 40 cm and 30 cm respectively. The visibility of the holes with the smallest diameters (1 mm) is the same for 50 and 40 cm while it is better for 30 cm, as can be expected due to the lower SNR. Carbon-fiber inserts, tabletops play a vital role in modern radiotherapy. One of the most important advantages of carbon-fiber tabletops is the lack of the gantry direction limitations. In this paper the attenuation of a carbon-fiber tabletop and its influence on a portal image quality were investigated. Dose attenuation effects, comparable to other measurements, were found. That effect influences dose distribution delivered to the target volume and can increase the time of irradiation needed to take a portal image. It has been found that the best conditions for taking portal image occur when the distance from the phantom (patient) to the portal is 40 cm and the portal is parallel to the tabletop. In such conditions one observes the

  8. Assessment of the influence of a carbon fiber tabletop on portal imaging

    International Nuclear Information System (INIS)

    The purpose of this paper was to investigate beam attenuation caused by a carbon-fiber tabletop and its influence on portal image quality. The dose was measured by a Farmer type jonization chamber. The measurements of the portal image quality were performed with an EPID QC phantom for 6 MV beam for a specified field size (covering all test elements of the phantom completely −26×26 cm2 in the isocenter, SSD 96.2 cm) and various portal—isocenter distances. The beam attenuation factor was measured for Polkam 16 treatment table with a carbon fiber tabletop. Carbon fiber tabletop induces beam attenuation in vertical direction by a factor of 3.39%. The lowest maximum deviation to the regression line for linearity was measured for 40 cm portal—phantom distance. The lowest signal to noise ratio was observed for the portal—phantom distance of 30 cm. This factor dropped by 9% for images with a tabletop. The difference in high contrast: horizontal is 3.64; 0.32; 3.25 for 50 cm, 40 cm and 30 cm respectively and vertical—3.64%; 0.32%; 4.01% for 50 cm, 40 cm and 30 cm respectively. The visibility of the holes with the smallest diameters (1 mm) is the same for 50 and 40 cm while it is better for 30 cm, as can be expected due to the lower SNR. Carbon-fiber inserts, tabletops play a vital role in modern radiotherapy. One of the most important advantages of carbon-fiber tabletops is the lack of the gantry direction limitations. In this paper the attenuation of a carbon-fiber tabletop and its influence on a portal image quality were investigated. Dose attenuation effects, comparable to other measurements, were found. That effect influences dose distribution delivered to the target volume and can increase the time of irradiation needed to take a portal image. It has been found that the best conditions for taking portal image occur when the distance from the phantom (patient) to the portal is 40 cm and the portal is parallel to the tabletop. In such conditions one observes

  9. High photon flux table-top coherent extreme ultraviolet source

    CERN Document Server

    Hädrich, Steffen; Rothhardt, Jan; Krebs, Manuel; Hoffmann, Armin; Pronin, Oleg; Pervak, Vladimir; Limpert, Jens; Tünnermann, Andreas

    2014-01-01

    High harmonic generation (HHG) enables extreme ultraviolet radiation with table-top setups. Its exceptional properties, such as coherence and (sub)-femtosecond pulse durations, have led to a diversity of applications. Some of these require a high photon flux and megahertz repetition rates, e.g. to avoid space charge effects in photoelectron spectroscopy. To date this has only been achieved with enhancement cavities. Here, we establish a novel route towards powerful HHG sources. By achieving phase-matched HHG of a megahertz fibre laser we generate a broad plateau (25 eV - 40 eV) of strong harmonics, each containing more than $10^{12}$ photons/s, which constitutes an increase by more than one order of magnitude in that wavelength range. The strongest harmonic (H25, 30 eV) has an average power of 143 $\\mu$W ($3\\cdot10^{13}$ photons/s). This concept will greatly advance and facilitate applications in photoelectron or coincidence spectroscopy, coherent diffractive imaging or (multidimensional) surface science.

  10. Evaluation of a Tabletop Emergency Preparedness Exercise for Pharmacy Students.

    Science.gov (United States)

    Pate, Adam; Bratberg, Jeffrey P; Robertson, Courtney; Smith, Gregory

    2016-04-25

    Objective. To describe the implementation and effect of an emergency preparedness laboratory activity on student knowledge, willingness to participate in emergency preparedness training, current level of preparedness, and the importance of a pharmacist's role in disaster response. Design. Second-year pharmacy students in the infectious disease module participated in a laboratory activity based on a basic disaster response tabletop exercise format. Three case-based scenarios involving infectious diseases were created by participating faculty members. Assessment. Surveys before and after the laboratory were used to assess the activity's effect on student knowledge, willingness to participate in emergency preparedness training, current level of preparedness, and the importance of a pharmacist's role in disaster response. In addition, the postsurvey assessed student perceptions of the activity's success at accomplishing faculty-specified outcomes from Appendix B of the Accreditation Council for Pharmacy Education's (ACPE) Standards. Conclusion. Implementation of an emergency response laboratory activity may improve overall students' knowledge of, confidence in, and understanding of their role as pharmacists in an emergency response, while incorporating a variety of skills and knowledge outcomes. PMID:27170821

  11. Spectral and imaging characterization of tabletop x-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, J; Faenov, A Ya; Pikuz, T A; Osterheld, A; Moon, S J; Fournier, K B; Nilsen, J; Skobelev, I Yu; Magunov, A I; Shlyaptsev, V N

    2000-12-01

    We have performed L-shell spectroscopy and one-dimensional (1-D) imaging of a line focus plasma from a laser-heated Fe polished slab using the tabletop COMET laser system at the Lawrence Livermore National Laboratory. These plasmas are used to generate a Ne-like Fe transient gain x-ray laser that is recorded simultaneously. A spherically-curved crystal spectrometer gives high resolution x-ray spectra of the n = 3-2 and n = 4-2 resonance lines with 1-D spatial resolution along the line focus. Spectra are presented for different laser pulse conditions. In addition, a variety of x-ray imaging techniques are described. We discuss imaging results from a double-slit x-ray camera with a spherically-curved crystal spectrometer. We show a high resolution Fe K-{alpha} spectrum from the x-ray laser target that indicates the presence of hot electrons in the x-ray laser plasma.

  12. Confocal coded aperture imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, Jr., Kenneth William (Harriman, TN); Thomas, Jr., Clarence E. (Knoxville, TN)

    2001-01-01

    A method for imaging a target volume comprises the steps of: radiating a small bandwidth of energy toward the target volume; focusing the small bandwidth of energy into a beam; moving the target volume through a plurality of positions within the focused beam; collecting a beam of energy scattered from the target volume with a non-diffractive confocal coded aperture; generating a shadow image of said aperture from every point source of radiation in the target volume; and, reconstructing the shadow image into a 3-dimensional image of the every point source by mathematically correlating the shadow image with a digital or analog version of the coded aperture. The method can comprise the step of collecting the beam of energy scattered from the target volume with a Fresnel zone plate.

  13. Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2008-01-01

    A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective...... is stored. The second stage applies the focused image lines from the first stage as input data. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The performance of SASB with a static image object is compared with DRF...

  14. Aperture Photometry Tool

    Science.gov (United States)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

    2012-07-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel "picking" and "zapping," and a selection of source and sky models. The radial-profile-interpolation source model

  15. Characteristics of a Saturated 18.9 nm Tabletop Laser Operating at 5 Hz Repetition Rate

    Energy Technology Data Exchange (ETDEWEB)

    Larotonda, M A; Luther, B M; Wang, Y; Liu, Y; Alessi, D; Berrill, M; Dummer, A; Brizuela, F; Menoni, C S; Marconi, M; Shlyaptsev, V N; Dunn, J; Rocca, J J

    2005-01-10

    We report the characteristics of a saturated high repetition rate Ni-like Mo laser at 18.9 nm. This table-top soft x-ray laser was pumped at 5 Hz repetition rate by 8 ps, 1 J optical laser pulses impinging at grazing incidence into a pre-created Mo plasma. The variation of the laser output intensity as a function of the grazing incidence angle of the main pump beam is reported. The maximum laser intensity was observed for an angle of 20 degrees, at which we measured a small signal gain of 65 cm{sup -1} and a gain-length product gxl > 15. Spatial coherence measurements resulting from a Young's double slit interference experiment show the equivalent incoherent source diameter is about 11 {micro}m. The peak spectral brightness is estimated to be of the order of 1 x 10{sup 24} photons s{sup -1} mm{sup -2} mrad{sup -2} within 0.01% spectral bandwidth. This type of practical, small scale, high repetition soft x-ray laser is of interest for many applications. This acts to reduce the sensitivity of burst properties to metallicity. Only the first anomalous burst in one model produces nuclei as heavy as A = 100. For the present choice of nuclear physics and accretion rates, other bursts and models make chiefly nuclei with A {approx} 64. The amount of carbon remaining after hydrogen-helium bursts is typically {approx}< 1% by mass, and decreases further as the ashes are periodically heated by subsequent bursts. For M = 3.5 x 10{sup -10} M{sub {circle_dot}} yr{sup -1} and solar metallicity, bursts are ignited in a hydrogen-free helium layer. At the base of this layer, up to 90% of the helium has already burned to carbon prior to the unstable ignition of the helium shell. These helium-ignited bursts have (a) briefer, brighter light curves with shorter tails; (b) very rapid rise times (< 0.1 s); and (c) ashes lighter than the iron group.

  16. Synthetic Aperture Radar Interferometry

    Science.gov (United States)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  17. Apodizer aperture for lasers

    Science.gov (United States)

    Jorna, Siebe; Siebert, Larry D.; Brueckner, Keith A.

    1976-11-09

    An aperture attenuator for use with high power lasers which includes glass windows shaped and assembled to form an annulus chamber which is filled with a dye solution. The annulus chamber is shaped such that the section in alignment with the axis of the incident beam follows a curve which is represented by the equation y = (r - r.sub.o).sup.n.

  18. Supine proton beam craniospinal radiotherapy using a novel tabletop adapter

    Energy Technology Data Exchange (ETDEWEB)

    Buchsbaum, Jeffrey C., E-mail: jbuchsba@iupui.edu [IU Health Proton Therapy Center, Bloomington, IN (United States); Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States); Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN (United States); Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN (United States); Besemer, Abby; Simmons, Joseph; Hoene, Ted; Simoneaux, Victor; Sandefur, Amy [IU Health Proton Therapy Center, Bloomington, IN (United States); Wolanski, Mark; Li, Zhao; Cheng, Chee-Wei [IU Health Proton Therapy Center, Bloomington, IN (United States); Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (United States)

    2013-04-01

    To develop a device that allows supine craniospinal proton and photon therapy to the vast majority of proton and photon facilities currently experiencing limitations as a result of couch design issues. Plywood and carbon fiber were used for the development of a prototype unit. Once this was found to be satisfactory after all design issues were addressed, computer-assisted design (CAD) was used and carbon fiber tables were built to our specifications at a local manufacturer of military and racing car carbon fiber parts. Clinic-driven design was done using real-time team discussion for a prototype design. A local machinist was able to construct a prototype unit for us in <2 weeks after the start of our project. Once the prototype had been used successfully for several months and all development issues were addressed, a custom carbon fiber design was developed in coordination with a carbon fiber manufacturer in partnership. CAD methods were used to design the units to allow oblique fields from head to thigh on patients up to 200 cm in height. Two custom-designed carbon fiber craniospinal tabletop designs now exist: one long and one short. Four are in successful use in our facility. Their weight tolerance is greater than that of our robot table joint (164 kg). The long unit allows for working with taller patients and can be converted into a short unit as needed. An affordable, practical means of doing supine craniospinal therapy with protons or photons can be used in most locations via the use of these devices. This is important because proton therapy provides a much lower integral dose than all other therapy methods for these patients and the supine position is easier for patients to tolerate and for anesthesia delivery. These units have been successfully used for adult and pediatric supine craniospinal therapy, proton therapy using oblique beams to the low pelvis, treatment of various spine tumors, and breast-sparing Hodgkin's therapy.

  19. TIDE: Lightweight Device Composition for Enhancing Tabletop Environments with Smartphone Applications

    DEFF Research Database (Denmark)

    Sicard, Leo; Tabard, Aurelien; Ramos, Juan David Hincapie;

    2013-01-01

    Interactive surfaces like tabletop computers provide large touch- enabled displays, support novel forms of interaction and collaboration, and extend computation to new environments. However, being a novel platform, the existing application pool is limited and applications existing for other......, maintaining privacy by limiting content transfer between devices, and enhancing the usefulness of tabletops with already existing smart- phone applications and software developers. We present the design and imple- mentation of TIDE, the study of different interaction techniques to manipulate TIDE......’s interactive content, and an analysis of different research directions. Initial user feedback shows that TIDE is easy to use, learnable, and convenient for colla- borative activities and private environments....

  20. The value of tabletop exercises and one-page planning documents.

    Science.gov (United States)

    Lasky, Mary

    2010-03-01

    Tabletop exercises are an excellent means for teaching people what a severe pandemic entails and for helping participants realise both the importance of planning and how to relate to an existing plan. Creating a one-page document to describe one's pandemic response plan and delineate trigger points enhances understanding of a complex plan and is excellent for guiding action during a pandemic. This paper will discuss the value of both tabletop exercises and one-page pandemic response plan summaries. In addition, it discusses the lessons learned from their use at the Johns Hopkins University Applied Physics Laboratory and at several nonprofit organisations in Howard County, Maryland. PMID:20494878

  1. Complex Aperture Networks

    CERN Document Server

    Owladeghaffari, Hamed

    2009-01-01

    A complex network approach on a rough fracture is developed. In this manner, some hidden metric spaces (similarity measurements) between apertures profiles are set up and a general evolutionary network in two directions (in parallel and perpendicular to the shear direction) is constructed. Evaluation of the emerged network shows the connectivity degree (distribution) of network, after a transition step; fall in to the stable states which are coincided with the Gaussian distribution. Based on this event and real observations of the complex network changes, an algorithm (COmplex Networks on Apertures: CONA) is proposed in which evolving of a network is accomplished using preferential detachments and attachments of edges (based on a competition and game manner) while the number of nodes is fixed. Also, evolving of clustering coefficients and number of edges display similar patterns as well as are appeared in shear stress, hydraulic conductivity and dilation changes, which can be engaged to estimate shear strengt...

  2. Configurable Aperture Space Telescope

    Science.gov (United States)

    Ennico, Kimberly; Bendek, Eduardo

    2015-01-01

    In December 2014, we were awarded Center Innovation Fund to evaluate an optical and mechanical concept for a novel implementation of a segmented telescope based on modular, interconnected small sats (satlets). The concept is called CAST, a Configurable Aperture Space Telescope. With a current TRL is 2 we will aim to reach TLR 3 in Sept 2015 by demonstrating a 2x2 mirror system to validate our optical model and error budget, provide straw man mechanical architecture and structural damping analyses, and derive future satlet-based observatory performance requirements. CAST provides an alternative access to visible and/or UV wavelength space telescope with 1-meter or larger aperture for NASA SMD Astrophysics and Planetary Science community after the retirement of HST

  3. Synthetic Aperture Radiometer Systems

    Science.gov (United States)

    LeVine, David M.

    1999-01-01

    Aperture synthesis is a new technology for passive microwave remote sensing from space which has the potential to overcome the limitations set in the past by antenna size. This is an interferometric technique in which pairs of small antennas and signal processing are used to obtain the resolution of a single large antenna. The technique has been demonstrated successfully at L-band with the aircraft prototype instrument, ESTAR. Proposals have been submitted to demonstrate this technology in space (HYDROSTAR and MIRAS).

  4. Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de

    2008-01-01

    A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze

  5. Subjective User Experience and Performance with Active Tangibles on a Tabletop Interfaces

    NARCIS (Netherlands)

    Erp, van Jan B.F.; Toet, Alexander; Meijer, Koos; Janssen, Joris; Jong, Arnoud

    2015-01-01

    We developed active tangibles (Sensators) that can be used in combination with multitouch tabletops and that can provide multisensory (visual, auditory, and vibrotactile) feedback. For spatial alignment and rotation tasks we measured subjective user experience and objective performance with these Se

  6. Educational Games for Early Childhood: Using Tabletop Surface Computers for Teaching the Arabic Alphabet

    DEFF Research Database (Denmark)

    Papadopoulos, Pantelis M.; Ibrahim, Zeinab; Karatsolis, Andreas

    2015-01-01

    This paper presents initial evaluation regarding the use of simple educational games on tabletop surface computers to teach Kindergarten students in Qatar the Arabic alphabet. This effort is part of the “Arabiyyatii” research project, a 3-year endeavor aimed to teach 5-year-olds Modern Standard...

  7. A Tabletop Board Game Interface for Multi-User Interaction with a Storytelling System

    NARCIS (Netherlands)

    Alofs, T.; Theune, M.; Swartjes, I.M.T.; Camurri, A.; Costa, C.

    2011-01-01

    The Interactive Storyteller is an interactive storytelling system with a multi-user tabletop interface. Our goal was to design a generic framework combining emergent narrative, where stories emerge from the actions of autonomous intelligent agents, with the social aspects of traditional board games.

  8. Capturing and Analyzing Verbal and Physical Collaborative Learning Interactions at an Enriched Interactive Tabletop

    Science.gov (United States)

    Martinez-Maldonado, Roberto; Dimitriadis, Yannis; Martinez-Monés, Alejandra; Kay, Judy; Yacef, Kalina

    2013-01-01

    Interactive tabletops can be used to provide new ways to support face-to-face collaborative learning. A little explored and somewhat hidden potential of these devices is that they can be used to enhance teachers' awareness of students' progress by exploiting captured traces of interaction. These data can make key aspects of collaboration…

  9. Compounding in synthetic aperture imaging.

    Science.gov (United States)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-09-01

    A method for obtaining compound images using synthetic aperture data is investigated using a convex array transducer. The new approach allows spatial compounding to be performed for any number of angles without reducing the frame rate or temporal resolution. This important feature is an intrinsic property of how the compound images are constructed using synthetic aperture data and an improvement compared with how spatial compounding is obtained using conventional methods. The synthetic aperture compound images are created by exploiting the linearity of delay-and-sum beamformation for data collected from multiple spherical emissions to synthesize multiple transmit and receive apertures, corresponding to imaging the tissue from multiple directions. The many images are added incoherently, to produce a single compound image. Using a 192-element, 3.5-MHz, λ-pitch transducer, it is demonstrated from tissue-phantom measurements that the speckle is reduced and the contrast resolution improved when applying synthetic aperture compound imaging. At a depth of 4 cm, the size of the synthesized apertures is optimized for lesion detection based on the speckle information density. This is a performance measure for tissue contrast resolution which quantifies the tradeoff between resolution loss and speckle reduction. The speckle information density is improved by 25% when comparing synthetic aperture compounding to a similar setup for compounding using dynamic receive focusing. The cystic resolution and clutter levels are measured using a wire phantom setup and compared with conventional application of the array, as well as to synthetic aperture imaging without compounding. If the full aperture is used for synthetic aperture compounding, the cystic resolution is improved by 41% compared with conventional imaging, and is at least as good as what can be obtained using synthetic aperture imaging without compounding. PMID:23007781

  10. Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Gammelmark, Kim Løkke;

    2006-01-01

    The paper describes the use of synthetic aperture (SA) imaging in medical ultrasound. SA imaging is a radical break with today's commercial systems, where the image is acquired sequentially one image line at a time. This puts a strict limit on the frame rate and the possibility of acquiring...... of SA imaging. Due to the complete data set, it is possible to have both dynamic transmit and receive focusing to improve contrast and resolution. It is also possible to improve penetration depth by employing codes during ultrasound transmission. Data sets for vector flow imaging can be acquired using...... short imaging sequences, whereby both the correct velocity magnitude and angle can be estimated. A number of examples of both phantom and in-vivo SA images will be presented measured by the experimental ultrasound scanner RASMUS to demonstrate the many benefits of SA imaging....

  11. Sequential Beamforming Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2013-01-01

    Synthetic aperture sequential beamforming (SASB) is a novel technique which allows to implement synthetic aperture beamforming on a system with a restricted complexity, and without storing RF-data. The objective is to improve lateral resolution and obtain a more depth independent resolution...

  12. Sparse synthetic aperture radar imaging with optimized azimuthal aperture

    Institute of Scientific and Technical Information of China (English)

    ZENG Cao; WANG MinHang; LIAO GuiSheng; ZHU ShengQi

    2012-01-01

    To counter the problem of acquiring and processing huge amounts of data for synthetic aperture radar (SAR) using traditional sampling techniques,a method for sparse SAR imaging with an optimized azimuthal aperture is presented.The equivalence of an azimuthal match filter and synthetic array beamforming is shown so that optimization of the azimuthal sparse aperture can be converted to optimization of synthetic array beamforming.The azimuthal sparse aperture,which is composed of a middle aperture and symmetrical bilateral apertures,can be obtained by optimization algorithms (density weighting and simulated annealing algorithms,respectively).Furthermore,sparse imaging of spectrum analysis SAR based on the optimized sparse aperture is achieved by padding zeros at null samplings and using a non-uniform Taylor window. Compared with traditional sampling,this method has the advantages of reducing the amount of sampling and alleviating the computational burden with acceptable image quality.Unlike periodic sparse sampling,the proposed method exhibits no image ghosts.The results obtained from airborne measurements demonstrate the effectiveness and superiority of the proposed method.

  13. High resolution coherent diffractive imaging with a table-top extreme ultraviolet source

    Energy Technology Data Exchange (ETDEWEB)

    Vu Le, Hoang, E-mail: vuhoangle@swin.edu.au; Ba Dinh, Khuong; Hannaford, Peter; Van Dao, Lap [Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122 (Australia)

    2014-11-07

    We demonstrate a resolution of 45 nm with a sample size down to 3 μm × 3 μm is achieved in a short exposure time of 2 s, from the diffraction pattern generated by a table-top high harmonic source at around 30 nm. By using a narrow-bandwidth focusing mirror, the diffraction pattern's quality is improved and the required exposure time is significantly reduced. In order to obtain a high quality of the reconstructed image, the ratio of the beam size to the sample size and the curvature of the focused beam need to be considered in the reconstruction process. This new experimental scheme is very promising for imaging sub-10 nm scale objects with a table-top source based on a small inexpensive femtosecond laser system.

  14. Pseudo-Weight: Making Tabletop Interaction with Virtual Objects More Tangible

    OpenAIRE

    Keller, Chantal; Bluteau, Jérémy; Blanch, Renaud; Coquillart, Sabine

    2012-01-01

    In this paper we show that virtual objects manipulated on a tabletop interaction device can be augmented to provide the illusion they have a weight. This weight offers a supplemental channel to provide information about graphical objects without cluttering the visual display. To create such a pseudo-weight illusion on a passive device, the pressure applied with the fingers during the interaction has to be captured. We show that this pressure can be estimated without hardware modification on s...

  15. Rapid Scanning Terahertz Time-Domain Magnetospectroscopy with a Table-Top Repetitive Pulsed Magnet

    OpenAIRE

    Noe, G. T.; Zhang, Q.; Lee, J.; E. Kato; Woods, G L; Nojiri, H.; Kono, J.

    2014-01-01

    We have performed terahertz time-domain magnetospectroscopy by combining a rapid scanning terahertz time-domain spectrometer based on the electronically coupled optical sampling method with a table-top mini-coil pulsed magnet capable of producing magnetic fields up to 30 T. We demonstrate the capability of this system by measuring coherent cyclotron resonance oscillations in a high-mobility two-dimensional electron gas in GaAs and interference-induced terahertz transmittance modifications in ...

  16. Feasibility study for an industrial superconducting table-top electron accelerator

    International Nuclear Information System (INIS)

    A concept of a table-top accelerator, consisting of a superconducting resonator and subsequent 6 standard TESLA cells working with a frequency of 1.3 GHz, is presented. Then electron gun is based on a photocathode. Especially described are the photocathode part, the laser system, the cryostat module, the RF system, the beam extraction, and the cryogenic facility. Finally the efficiency and the costs are considered, (HSI)

  17. Quantitative Chemically-Specific Coherent Diffractive Imaging of Buried Interfaces using a Tabletop EUV Nanoscope

    OpenAIRE

    Shanblatt, Elisabeth R.; Porter, Christina L.; Gardner, Dennis F.; Mancini, Giulia F.; Karl Jr., Robert M.; Tanksalvala, Michael D.; Bevis, Charles S.; Vartanian, Victor H.; Kapteyn, Henry C.; Adams, Daniel E.; Murnane, Margaret M.

    2016-01-01

    Characterizing buried layers and interfaces is critical for a host of applications in nanoscience and nano-manufacturing. Here we demonstrate non-invasive, non-destructive imaging of buried interfaces using a tabletop, extreme ultraviolet (EUV), coherent diffractive imaging (CDI) nanoscope. Copper nanostructures inlaid in SiO2 are coated with 100 nm of aluminum, which is opaque to visible light and thick enough that neither optical microscopy nor atomic force microscopy can image the buried i...

  18. TangiWheel: A widget for manipulating collections on tabletop displays supporting hybrid Input modality

    OpenAIRE

    Catalá Bolós, Alejandro; García Sanjuan, Fernando; Jaén Martínez, Francisco Javier; Mocholi Agües, Jose Antonio

    2012-01-01

    In this paper we present TangiWheel, a collection manipulation widget for tabletop displays. Our implementation is flexible, allowing either multi-touch or interaction, or even a hybrid scheme to better suit user choice and convenience. Different TangiWheel aspects and features are compared with other existing widgets for collection manipulation. The study reveals that TangiWheel is the first proposal to support a hybrid input modality with large resemblance levels between touch and tangible ...

  19. Collaborative strategic reading on multi-touch and multi-user digital tabletop displays

    OpenAIRE

    Maslamani, Jaber Ali; Windeatt, Scott; Olivier, Patrick; Heslop, Phil; Kharrufa, Ahmed; Shearer, John; Balaam, Madeline

    2012-01-01

    This paper is part of a work-in-progress that reports on the design, development, and evaluation of a Digital Collaborative Strategic Reading (DCSR) application with regard to its effectiveness in improving English as a second language (ESL) reading comprehension. The DCSR application allows users to read collaboratively on multi-touch and multi-user digital tabletop displays that support both face-to-face and computer-based interaction. The application is designed to provide systematic instr...

  20. A simple table-top demonstration of radiation pressure on a macroscopic object

    CERN Document Server

    Jesensky, G; Khomenko, O; Kim, W J

    2016-01-01

    We report a simple demonstration of radiation pressure on a table-top experiment. Utilizing dynamic force microscopy in ambient environment, the resonant motion of a cm-sized cantilever driven by an amplitude-modulated diode laser is directly observed. Our versatile setup involves a host of exciting techniques that are relevant in precision force measurements and represents an ideal experiment in the undergraduate laboratory.

  1. Table-top deterministic and collective colloidal assembly using videoprojector lithography

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Micrometric resolution substrates are made at low cost using a videoprojector. • Fabricated patterns could be used as substrates for capillary force assembly. • Arrays of organized particles are made using a table-top capillary assembly tool. • This process offers a new bridge between the colloidal domain and the chip world. - Abstract: In the field of micro- and nanotechnology, most lithography and fabrication tools coming from the microelectronic industry are expensive, time-consuming and may need some masks that have to be subcontracted. Such approach is not suitable for other fields that require rapid prototyping such as chemistry, life science or energy and may hinder research creativity. In this work, we present two table-top equipments dedicated to the fabrication of deterministic colloidal particles assemblies onto micro-structured substrates. We show that, with a limited modification of the optics of a standard videoprojector, it is possible to quickly obtain substrates with thousands of micrometric features. Then, we combine these substrates with thermodynamic colloidal assembly and generate arrays of particles without defects. This work opens the way to a simple and table-top fabrication of devices based on colloidal particles

  2. Table-top deterministic and collective colloidal assembly using videoprojector lithography

    Energy Technology Data Exchange (ETDEWEB)

    Cordeiro, J. [Univ Grenoble Alpes, F-38000 Grenoble (France); CNRS, LTM, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38000 Grenoble (France); Zelsmann, M., E-mail: marc.zelsmann@cea.fr [Univ Grenoble Alpes, F-38000 Grenoble (France); CNRS, LTM, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38000 Grenoble (France); Honegger, T. [Univ Grenoble Alpes, F-38000 Grenoble (France); CNRS, LTM, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38000 Grenoble (France); Picard, E.; Hadji, E. [Univ Grenoble Alpes, F-38000 Grenoble (France); CEA, INAC-SP2M, F-38000 Grenoble (France); Peyrade, D. [Univ Grenoble Alpes, F-38000 Grenoble (France); CNRS, LTM, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38000 Grenoble (France)

    2015-09-15

    Graphical abstract: - Highlights: • Micrometric resolution substrates are made at low cost using a videoprojector. • Fabricated patterns could be used as substrates for capillary force assembly. • Arrays of organized particles are made using a table-top capillary assembly tool. • This process offers a new bridge between the colloidal domain and the chip world. - Abstract: In the field of micro- and nanotechnology, most lithography and fabrication tools coming from the microelectronic industry are expensive, time-consuming and may need some masks that have to be subcontracted. Such approach is not suitable for other fields that require rapid prototyping such as chemistry, life science or energy and may hinder research creativity. In this work, we present two table-top equipments dedicated to the fabrication of deterministic colloidal particles assemblies onto micro-structured substrates. We show that, with a limited modification of the optics of a standard videoprojector, it is possible to quickly obtain substrates with thousands of micrometric features. Then, we combine these substrates with thermodynamic colloidal assembly and generate arrays of particles without defects. This work opens the way to a simple and table-top fabrication of devices based on colloidal particles.

  3. Isolated attosecond soft X-rays and water window XAFS

    Science.gov (United States)

    Biegert, Jens

    2016-05-01

    We demonstrate generation of isolated attosecond soft X-ray pulses with duration less than 350 as at the carbon K-edge at 284 eV. This reproducible and CEP stable attosecond soft X-ray continuum covers the entire water window from 200 eV to 550 eV with a flux of 7.3x 107 photons/s and corresponds to a pulse energy of 2.9 pJ. We demonstrate the utility of our table-top source through soft X-ray near-edge fine-structure spectroscopy at K-shell absorption edges in condensed matter and retrieve the specific absorption features corresponding to the binding orbitals. We believe that these results herald attosecond material science by bridging the gap between ultrafast temporal resolution and element specific probing at the fundamental absorption edges of matter.

  4. Dynamic gain aperture modelocking in picosecond regime based on cascaded second-order nonlinearity.

    Science.gov (United States)

    Mondal, Shyamal; Mukherjee, Shouvik; Singh, Satya Pratap; Rand, Stephen C; Bhattacharya, Sayantan; Das, Amit C; Datta, Prasanta Kumar

    2016-07-11

    The operation of a cascaded second-order mode-locked Nd:YVO4 laser has been investigated considering it as a soft-aperture Kerr lens type and using complex beam parameters. A self consistent complex beam propagation method is used to incorporate the effect of cascaded Kerr nonlinearity on radially varying gain aperturing. The analysis deduces a stable pulsewidth of ~9.5 ps which agrees well with the experimental value of 10.3 ps. PMID:27410804

  5. Dynamic gain aperture modelocking in picosecond regime based on cascaded second-order nonlinearity.

    Science.gov (United States)

    Mondal, Shyamal; Mukherjee, Shouvik; Singh, Satya Pratap; Rand, Stephen C; Bhattacharya, Sayantan; Das, Amit C; Datta, Prasanta Kumar

    2016-07-11

    The operation of a cascaded second-order mode-locked Nd:YVO4 laser has been investigated considering it as a soft-aperture Kerr lens type and using complex beam parameters. A self consistent complex beam propagation method is used to incorporate the effect of cascaded Kerr nonlinearity on radially varying gain aperturing. The analysis deduces a stable pulsewidth of ~9.5 ps which agrees well with the experimental value of 10.3 ps.

  6. Tissue Harmonic Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Rasmussen, Joachim

    The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue....... Clinical scans were conducted in collaboration with medical professionals at Copenhagen University. In a series of double blinded trials, image quality and recognition of pathology using SASB with THI was compared with conventional THI. The results of the clinical trial documented, that SASB with THI...

  7. Tabletop Ultrabright Kiloelectronvolt X-Ray Sources from Xe and Kr Hollow Atom States

    Science.gov (United States)

    Sankar, Poopalasingam

    Albert Einstein, the father of relativity, once said, "Look deep into nature, and then you will understand everything better". Today available higher resolution tabletop tool to look deep into matters and living thing is an x-ray source. Although the available tabletop x-rays sources of the 20th century, such as the ones used for medical or dental x-rays are tremendously useful for medical diagnostics and industry, a major disadvantage is that they have low quality skillful brightness, which limits its resolution and accuracy. In the other hand, x-ray free-electrons laser (XFEL) and synchrotron radiation sources provided extreme bright x-rays. However, number of applications of XFEL and synchrotron such as medical and industrials, has been hampered by their size, complexity, and cost. This has set a goal of demonstrating x-ray source with enough brightness for potential applications in an often-called tabletop compact x-ray source that could be operated in university laboratory or hospitals. We have developed two tabletop ultrabright keV x-ray sources, one from a Xe hollow-atom states and the other one from Kr hollow-atom stares with a unique characteristic that makes them complementary to currently-available extreme-light sources; XFEL, and synchrotron x-ray source. Upgraded tabletop ultra-fast KrF* pump-laser interacts with target rare-gas clusters and produces hollow-atom states, which later coherently collapse to the empty inner-shell and thereby generate keV x-ray radiation. The KrF* pump-laser beam is self-focused and forms a self-channel to guide the generated x-ray radiation in the direction of the pump-laser beam to produce directed x-ray beam. Xe (M) x-ray source operates at 1.2-1.6 nm wavelength while the Kr(L) x-ray source operates in 600-800 pm wavelength. System is mounted upon 3 optical-tables (5´x12´) with two KrF amplifiers at a repetition rate of 0.1 Hz. A lower bound for brightness value for both Xe and Kr x-ray sources is 1026 photons s-1mm-2

  8. Optimizing Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Spatial compound images are constructed from synthetic aperture data acquired using a linear phased-array transducer. Compound images of wires, tissue, and cysts are created using a method, which allows both transmit and receive compounding without any loss in temporal resolution. Similarly to...... optimal for lesion detection. Synthetic aperture data are acquired from unfocused emissions and 154 compound images are constructed by synthesizing different aperture configurations with more or less compounding, all maintaining a constant resolution across depth corresponding to an f-number of 2.0 for...... transmit and receive. The same configurations are used for scanning a phantom with cysts, and it is demonstrated how an improved cysts contrast follows from an aperture configuration, which gives a higher value for the performance measure extracted from the phantom without cysts. A correlation value R = 0...

  9. Synthetic Aperture Radar - Hardware Development

    OpenAIRE

    Rosner, V.; Seller, R.; L. Dudas; Kazi, K.; Miko, G.

    2009-01-01

    Experimental real and synthetic aperture radar are developed from the base-band digital unit to the analogue RF parts, based on solid state units, using pulse compression for radar imaging. Proper QPSK code is found for matched filter.

  10. Compounding in synthetic aperture imaging

    DEFF Research Database (Denmark)

    Hansen, J. M.; Jensen, J. A.

    2012-01-01

    A method for obtaining compound images using synthetic aperture data is investigated using a convex array transducer. The new approach allows spatial compounding to be performed for any number of angles without reducing the frame rate or temporal resolution. This important feature is an intrinsic...... from multiple spherical emissions to synthesize multiple transmit and receive apertures, corresponding to imaging the tissue from multiple directions. The many images are added incoherently, to produce a single compound image. Using a 192-element, 3.5-MHz, λ-pitch transducer, it is demonstrated from...... tissue-phantom measurements that the speckle is reduced and the contrast resolution improved when applying synthetic aperture compound imaging. At a depth of 4 cm, the size of the synthesized apertures is optimized for lesion detection based on the speckle information density. This is a performance...

  11. Synthetic aperture controlled source electromagnetics

    OpenAIRE

    Fan, Y.; Snieder, R.; Slob, E.; Hunziker, J.W.; Singer, J.; Sheiman, J.; Rosenquist, M.

    2010-01-01

    Controlled‐source electromagnetics (CSEM) has been used as a de‐risking tool in the hydrocarbon exploration industry. Although there have been successful applications of CSEM, this technique is still not widely used in the industry because the limited types of hydrocarbon reservoirs CSEM can detect. In this paper, we apply the concept of synthetic aperture to CSEM data. Synthetic aperture allows us to design sources with specific radiation patterns for different purposes. The ability to detec...

  12. Picosecond soft-x-ray pulses from a high-intensity laser-plasma source.

    Science.gov (United States)

    Pelletier, J F; Chaker, M; Kieffer, J C

    1996-07-15

    We report time-resolved spectroscopic analysis of laser-produced plasma x-ray sources. Plasmas produced by a 400-fs 1-TW tabletop laser are characterized with a transmission grating spectrometer coupled to a soft-x-ray streak camera. Soft-x-ray radiation in the 1-6-nm range with durations of 2-7 ps is observed for copper and tantalum plasmas. The effect of incident laser energy on the x-ray pulse duration is also investigated. PMID:19876245

  13. NPS high resolution synthetic aperture sonar

    OpenAIRE

    Welter, Joseph Donald

    1995-01-01

    This thesis investigated the use of synthetic aperture techniques to achieve a long effective aperture, high resolution, imaging sonar. The approach included a full simulation of the system using the MATLAB programming environment that provided a model for developing six data processing algorithms and a working 25KHz, 1 m baseline, air medium synthetic aperture sonar. The six azimuthal processing techniques included: (1) a normal, real aperture, (2) an unfocussed synthetic aperture, (3) a hyb...

  14. Experimental plasma astrophysics using a T{sup 3} (Table-top Terawatt) laser

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, T.

    1996-11-01

    Lasers that can deliver immense power of Terawatt (10{sup 12}W) and can still compactly sit on a Table-Top (T{sup 3} lasers) emerged in the 1990s. The advent of these lasers allows us to access to regimes of astronomical physical conditions that once thought impossible to realize in a terrestrial laboratory. We touch on examples that include superhigh pressure materials that may resemble the interior of giant planets and white dwarfs and of relativistic temperature plasmas that may exist in the early cosmological epoch and in the neighborhood of the blackhole event horizon.

  15. From Tabletop RPG to Interactive Storytelling: Definition of a Story Manager for Videogames

    Science.gov (United States)

    Delmas, Guylain; Champagnat, Ronan; Augeraud, Michel

    Adding narrative in computer game is complicated because it may restrict player interactivity. Our aim is to design a controller that dynamically built a plot, through the game execution, centred on player's actions. Tabletop Role-playing games manage to deal with this goal. This paper presents a study of role-playing games, their organization, and the models commonly used for narrative generation. It then deduces a proposition of components and data structures for interactive storytelling in videogames. A prototype of a social game has been developed as example.

  16. Soft Drop

    CERN Document Server

    Larkoski, Andrew J; Soyez, Gregory; Thaler, Jesse

    2014-01-01

    We introduce a new jet substructure technique called "soft drop declustering", which recursively removes soft wide-angle radiation from a jet. The soft drop algorithm depends on two parameters--a soft threshold $z_\\text{cut}$ and an angular exponent $\\beta$--with the $\\beta = 0$ limit corresponding roughly to the (modified) mass drop procedure. To gain an analytic understanding of soft drop and highlight the $\\beta$ dependence, we perform resummed calculations for three observables on soft-dropped jets: the energy correlation functions, the groomed jet radius, and the energy loss due to soft drop. The $\\beta = 0$ limit of the energy loss is particularly interesting, since it is not only "Sudakov safe" but also largely insensitive to the value of the strong coupling constant. While our calculations are strictly accurate only to modified leading-logarithmic order, we also include a discussion of higher-order effects such as multiple emissions and (the absence of) non-global logarithms. We compare our analytic r...

  17. High resolution non-iterative aperture synthesis.

    Science.gov (United States)

    Kraczek, Jeffrey R; McManamon, Paul F; Watson, Edward A

    2016-03-21

    The maximum resolution of a multiple-input multiple-output (MIMO) imaging system is determined by the size of the synthetic aperture. The synthetic aperture is determined by a coordinate shift using the relative positions of the illuminators and receive apertures. Previous methods have shown non-iterative phasing for multiple illuminators with a single receive aperture for intra-aperture synthesis. This work shows non-iterative phasing with both multiple illuminators and multiple receive apertures for inter-aperture synthesis. Simulated results show that piston, tip, and tilt can be calculated using inter-aperture phasing after intra-aperture phasing has been performed. Use of a fourth illuminator for increased resolution is shown. The modulation transfer function (MTF) is used to quantitatively judge increased resolution. PMID:27136816

  18. Soft Skills

    OpenAIRE

    Schenker-Wicki, Andrea; Maiorano, Michel

    2008-01-01

    Der Begriff Soft Skills wird sehr unterschiedlich verwendet. Wir verstehen darunter überfachliche, nicht berufsspezifische Kompetenzen, welche für den Erfolg in der Arbeitswelt unabdingbar sind. Sie umfassen sowohl die Fähigkeit, mit anderen zu kommunizieren und zusammenzuarbeiten (interpersonell) als auch sich selbst zu organisieren und zu disziplinieren (intrapersonell). Zu den Soft Skills zählen im Wesentlichen die Kommunikations-, Team- und Konfliktlösungs- sowie die Motivationsfähigk...

  19. Study of energy transfer in table-top X-pinch driven by a water line

    Energy Technology Data Exchange (ETDEWEB)

    Beg, F N [Mechanical and Aerospace Department, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA92093-0411 (United States); Zhang, T [Mechanical and Aerospace Department, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA92093-0411 (United States); Fedin, D [Mechanical and Aerospace Department, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA92093-0411 (United States); Beagen, B [Anglo Chinese Junior College, 25 Dover Close East, Singapore 139745 (Singapore); Chua, E [Anglo Chinese Junior College, 25 Dover Close East, Singapore 139745 (Singapore); Lee, J Y [Anglo Chinese Junior College, 25 Dover Close East, Singapore 139745 (Singapore); Rawat, R S [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Lee, P [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2007-08-15

    The current passing through X-pinches and the energy transferring from the pulse forming line to the load are modelled using a simple LCR circuit. A comparison of the electrical properties of two table-top X-pinch devices is made. It was found that up to 25% of the stored energy is transferred from the water transmission line to the load in the University of California,San Diego (UCSD) table-top X-pinch before x-ray emission starts. The highest energy transmitted (75%) is found after the current peak. In comparison, only 3% of the energy is transferred to the load in the National Institute of Education (NIE) X-pinch device just after the maximum current peak. The highest energy (25%) transmitted to the plasma occurs long after the current peak. The plasma in both devices is visually and qualitatively similar. However, the UCSD device emits intense x-rays with no x-rays observed in the NIE device. This observation is consistent with the electrical circuit analysis.

  20. Synthetic Aperture Radar - Hardware Development

    Directory of Open Access Journals (Sweden)

    V. Rosner

    2009-06-01

    Full Text Available Experimental real and synthetic aperture radar are developed from the base-band digital unit to the analogue RF parts, based on solid state units, using pulse compression for radar imaging. Proper QPSK code is found for matched filter.

  1. Ultrasound fields from triangular apertures

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    1996-01-01

    The pulsed field from a triangular aperture mounted in an infinite, rigidbaffle is calculated. The approach of spatial impulse responses,as developed by Tupholme and Stepanishen, is used. By this both the emitted and received pulsed ultrasound field can be found for any transducerexcitation...

  2. Microfabricated rubber microscope using soft solid immersion lenses

    OpenAIRE

    Gambin, Yann; Legrand, Olivier; Quake, Stephen R

    2006-01-01

    We show here a technique of soft lithography to microfabricate efficient solid immersion lenses (SIL) out of rubber elastomers. The light collection efficiency of a lens system is described by its numerical aperture (NA), and is critical for applications as epifluorescence microscopy [B. Herman, Fluorescence Microscopy (BIOS Scientific, Oxford/Springer, United Kingdom, 1998). While most simple lens systems have numerical apertures less than 1, the lenses described here have NA=1.25. Better pe...

  3. RoMo: Avoiding Conflicts Between the Physical and Digital Model in Tabletop Interfaces with Robotic Tangibles

    DEFF Research Database (Denmark)

    Pedersen, Esben Warming; Hornbæk, Kasper Anders Søren

    2011-01-01

    In TUIs, physical/digital conflicts can occur when the digital model does not match the model implied by the spatial lay- out of tangibles. We show how tangible tabletop interfaces (TTI) can be modified to allow robot movement of tangi- bles, thereby avoiding conflicts. We present RoMo, an open...

  4. Designing and conducting tabletop exercises to assess public health preparedness for manmade and naturally occurring biological threats

    Directory of Open Access Journals (Sweden)

    Dausey David J

    2007-05-01

    Full Text Available Abstract Background Since 2001, state and local health departments in the United States (US have accelerated efforts to prepare for high-impact public health emergencies. One component of these activities has been the development and conduct of exercise programs to assess capabilities, train staff and build relationships. This paper summarizes lessons learned from tabletop exercises about public health emergency preparedness and about the process of developing, conducting, and evaluating them. Methods We developed, conducted, and evaluated 31 tabletop exercises in partnership with state and local health departments throughout the US from 2003 to 2006. Participant self evaluations, after action reports, and tabletop exercise evaluation forms were used to identify aspects of the exercises themselves, as well as public health emergency responses that participants found more or less challenging, and to highlight lessons learned about tabletop exercise design. Results Designing the exercises involved substantial collaboration with representatives from participating health departments to assure that the scenarios were credible, focused attention on local preparedness needs and priorities, and were logistically feasible to implement. During execution of the exercises, nearly all health departments struggled with a common set of challenges relating to disease surveillance, epidemiologic investigations, communications, command and control, and health care surge capacity. In contrast, performance strengths were more varied across participating sites, reflecting specific attributes of individual health departments or communities, experience with actual public health emergencies, or the emphasis of prior preparedness efforts. Conclusion The design, conduct, and evaluation of the tabletop exercises described in this report benefited from collaborative planning that involved stakeholders from participating health departments and exercise developers and

  5. The study on aperture configuration of optical synthetic aperture imaging system

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A model based on Fourier domain consideration on aperture configuration of optical synthetic aperture imaging system is introduced in this paper. The derivation of the model is directly linked to the restoration error of the original object from the recorded image. The aperture configuration is a function of the maximum frequency of interest, and takes into account the diameter of the aperture. The simulative results of genetic algorithms illustrate the usefulness of this model for designing a synthetic aperture optical imaging system, and the aperture configuration of a good synthetic aperture optical imaging system should be non-redundant.

  6. Short term dynamic aperture with AC dipoles

    CERN Document Server

    Mönig, Saskia; Persson, Tobias Hakan Bjorn; Coello De Portugal, Jaime; Langner, Andy; Tomas, Rogelio; CERN. Geneva. ATS Department

    2015-01-01

    The dynamic aperture of an accelerator is determined by its non-linear components and errors. Control of the dynamic aperture is important for a good understanding and operation of the accelerator. The AC dipole, installed in the LHC for the diagnostic of linear and non-linear optics, could serve as a tool for the determination of the dynamic aperture. However, since the AC dipole itself modifies the non-linear dynamics, the dynamic aperture with and without AC dipole are expected to differ. The effect of the AC dipole on the dynamic aperture is studied within this note.

  7. Soft electronics for soft robotics

    Science.gov (United States)

    Kramer, Rebecca K.

    2015-05-01

    As advanced as modern machines are, the building blocks have changed little since the industrial revolution, leading to rigid, bulky, and complex devices. Future machines will include electromechanical systems that are soft and elastically deformable, lending them to applications such as soft robotics, wearable/implantable devices, sensory skins, and energy storage and transport systems. One key step toward the realization of soft systems is the development of stretchable electronics that remain functional even when subject to high strains. Liquid-metal traces embedded in elastic polymers present a unique opportunity to retain the function of rigid metal conductors while leveraging the deformable properties of liquid-elastomer composites. However, in order to achieve the potential benefits of liquid-metal, scalable processing and manufacturing methods must be identified.

  8. Table-top natural uranium subcritical assembly for nuclear engineering education

    International Nuclear Information System (INIS)

    A small water-moderated, natural uranium, table-top subcritical assembly has been used in teaching basic concepts of neutron diffusion, scattering, absorption, and multiplication in nuclear reactors. The assembly consists of a transparent Plexiglas tank, 0.7 m in height and 0.6 m in diameter. It contains a Plexiglas grid plate with positions for 60 aluminum-clad natural uranium metal fuel slugs, a central 253CF or PuBe neutron source, and a BF3 thermal neutron detector. Pieces of common materials encountered in nuclear reactors are used to illustrate different neutron absorption and scattering properties. The tank is portable with the water removed, and can be set up in a laboratory or classroom in a short time

  9. Table-top solar flares produced with laser driven magnetic reconnections

    International Nuclear Information System (INIS)

    The American Nuclear Society (ANS) has presented the prestigious Edward Teller award to Dr. Bruce A. Remington during the 2011 IFSA conference due to his 'pioneering scientific work in the fields of inertial confinement fusion (ICF), and especially developing an international effort in high energy density laboratory astrophysics' [1,2]. This is a great acknowledgement to the subject of high energy density laboratory astrophysics. In this context, we report here one experiment conducted to model solar flares in the laboratory with intense lasers [3]. The mega-gauss -scale magnetic fields produced by laser produced plasmas can be used to make magnetic reconnection topology. We have produced one table-top solar flare in our laboratory experiment with the same geometric setup as associated with solar flares. (authors)

  10. Progress in table-top transient collisional excitation x-ray lasers at LLNL

    Energy Technology Data Exchange (ETDEWEB)

    Da Silva, L B; Dunn, J; Li, Y; Nilsen, J; Osterheld, A; Shepherd, R; Shlyaptsev, V N

    1999-02-07

    We present progress in experiments for high efficiency Ne-like and Ni-like ion x-ray lasers using the transient collisional excitation scheme. Experimental results have been obtained on the COMET 15 TW table-top laser system at the Lawrence Livermore National Laboratory (LLNL). The plasma formation, ionization and collisional excitation of the x-ray laser have been optimized using two sequential laser pulses of 600 ps and 1 ps duration with an optional pre-pulse. We have observed high gains up to 55 cm{sup {minus}1} in Ne-like and Ni-like ion schemes for various atomic numbers. We report strong output for the 4d - 4p line in lower Z Ni-like ion sequence for Mo to Y, lasing from {approximately}190 {angstrom} to 240 {angstrom}, by pumping with less than 5 J energy on target.

  11. Quantitative Chemically-Specific Coherent Diffractive Imaging of Buried Interfaces using a Tabletop EUV Nanoscope

    CERN Document Server

    Shanblatt, Elisabeth R; Gardner, Dennis F; Mancini, Giulia F; Karl, Robert M; Tanksalvala, Michael D; Bevis, Charles S; Vartanian, Victor H; Kapteyn, Henry C; Adams, Daniel E; Murnane, Margaret M

    2016-01-01

    Characterizing buried layers and interfaces is critical for a host of applications in nanoscience and nano-manufacturing. Here we demonstrate non-invasive, non-destructive imaging of buried interfaces using a tabletop, extreme ultraviolet (EUV), coherent diffractive imaging (CDI) nanoscope. Copper nanostructures inlaid in SiO2 are coated with 100 nm of aluminum, which is opaque to visible light and thick enough that neither optical microscopy nor atomic force microscopy can image the buried interfaces. Short wavelength (29 nm) high harmonic light can penetrate the aluminum layer, yielding high-contrast images of the buried structures. Moreover, differences in the absolute reflectivity of the interfaces before and after coating reveal the formation of interstitial diffusion and oxidation layers at the Al-Cu and Al-SiO2 boundaries. Finally, we show that EUV CDI provides a unique capability for quantitative, chemically-specific imaging of buried structures, and the material evolution that occurs at these buried ...

  12. Table-top solar flares produced with laser driven magnetic reconnections

    Directory of Open Access Journals (Sweden)

    Zhong J.Y.

    2013-11-01

    Full Text Available The American Nuclear Society (ANS has presented the prestigious Edward Teller award to Dr. Bruce A. Remington during the 2011 IFSA conference due to his “pioneering scientific work in the fields of inertial confinement fusion (ICF, and especially developing an international effort in high energy density laboratory astrophysics” [1,2]. This is a great acknowledgement to the subject of high energy density laboratory astrophysics. In this context, we report here one experiment conducted to model solar flares in the laboratory with intense lasers [3]. The mega-gauss –scale magnetic fields produced by laser produced plasmas can be used to make magnetic reconnection topology. We have produced one table-top solar flare in our laboratory experiment with the same geometric setup as associated with solar flares.

  13. Development and Evaluation of Disaster Information Management System Using Digital Pens and Tabletop User Interfaces

    Science.gov (United States)

    Fukada, Hidemi; Kobayashi, Kazue; Satou, Kenji; Kawana, Hideyuki; Masuda, Tomohiro

    Most traditional disaster information systems are necessary to post expert staff with high computer literacy to operate the system quickly and correctly in the tense situation when a disaster occurs. However, in the current disaster response system of local governments, it is not easy for local governments to post such expert staff because they are struggling with staff cuts due to administrative and fiscal reform. In this research, we propose a disaster information management system that can be easily operated, even under the disorderly conditions of a disaster, by municipal personnel in charge of disaster management. This system achieves usability enabling easy input of damage information, even by local government staff with no expertise, by using a digital pen and tabletop user interface. Evaluation was conducted by prospective users using a prototype, and the evaluation results are satisfactory with regard to the function and operationality of the proposed system.

  14. Tabletop Nanometer Extreme Ultraviolet Imaging in an Extended Reflection Mode using Coherent Fresnel Ptychography

    CERN Document Server

    Seaberg, Matthew D; Gardner, Dennis F; Shanblatt, Elisabeth R; Murnane, Margaret M; Kapteyn, Henry C; Adams, Daniel E

    2013-01-01

    We demonstrate high resolution extreme ultraviolet (EUV) coherent diffractive imaging in the most general reflection geometry by combining ptychography with tilted plane correction. This method makes it possible to image extended surfaces at any angle of incidence. Refocused light from a tabletop coherent high harmonic light source at 29 nm illuminates a nanopatterned surface at 45 degree angle of incidence. The reconstructed image contains quantitative amplitude and phase (in this case pattern height) information, comparing favorably with both scanning electron microscope and atomic force microscopy images. In the future, this approach will enable imaging of complex surfaces and nanostructures with sub-10 nm-spatial resolution and fs-temporal resolution, which will impact a broad range of nanoscience and nanotechnology including for direct application in actinic inspection in support of EUV lithography.

  15. Soft Clouding

    DEFF Research Database (Denmark)

    Søndergaard, Morten; Markussen, Thomas; Wetton, Barnabas;

    2012-01-01

    Soft Clouding is a blended concept, which describes the aim of a collaborative and transdisciplinary project. The concept is a metaphor implying a blend of cognitive, embodied interaction and semantic web. Furthermore, it is a metaphor describing our attempt of curating a new semantics of sound...... brought together in one transdisciplinary process of curating a semantics of sound: Technological, Humanistic /Curatorial, and Design / Action-based practice....

  16. Soft Trencher

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Excavation near existing electrical lines, gas lines and other underground utilities can be dangerous and time consuming. A self propelled trencher called the Soft Trencher developed by Battelle Memorial Institute, Columbus, Ohio uses supersonic air to loosen dirt which is then vacuumed up into a truck or piled into a windrow for later removal of backfill. The supersonic air used to break up the soil is harmless to underground utilities and cables. Unlike traditional excavation methods there ...

  17. Aperture scanning Fourier ptychographic microscopy

    Science.gov (United States)

    Ou, Xiaoze; Chung, Jaebum; Horstmeyer, Roarke; Yang, Changhuei

    2016-01-01

    Fourier ptychographic microscopy (FPM) is implemented through aperture scanning by an LCOS spatial light modulator at the back focal plane of the objective lens. This FPM configuration enables the capturing of the complex scattered field for a 3D sample both in the transmissive mode and the reflective mode. We further show that by combining with the compressive sensing theory, the reconstructed 2D complex scattered field can be used to recover the 3D sample scattering density. This implementation expands the scope of application for FPM and can be beneficial for areas such as tissue imaging and wafer inspection. PMID:27570705

  18. Ultrasonic large aperture imaging system

    International Nuclear Information System (INIS)

    A new ultrasonic large aperture imaging technique is described. This device combines a focussed transducer as a transmitter, producing a small ultrasonic beam, with N transducers as receivers. We show that is possible to considerably reduce the number of receivers if, on the one hand, we limit the reconstitution process to the emitter beam area and, on the other hand, we ensure that the artefacts, caused by the spatial sampling of the reception, are outside this area. Under these conditions, the result is a high resolution image which does not require large reconstitution processing times. Theoretical and experimental results are given

  19. The Large Aperture GRB Observatory

    CERN Document Server

    Allard, D; Asorey, H; Barros, H; Bertou, X; Castillo, M; Chirinos, J M; De Castro, A; Flores, S; González, J; Berisso, M Gomez; Grajales, J; Guada, C; Day, W R Guevara; Ishitsuka, J; López, J A; Martínez, O; Melfo, A; Meza, E; Loza, P Miranda; Barbosa, E Moreno; Murrugarra, C; Núñez, L A; Ormachea, L J Otiniano; Pérez, G; Perez, Y; Ponce, E; Quispe, J; Quintero, C; Rivera, H; Rosales, M; Rovero, A C; Saavedra, O; Salazar, H; Tello, J C; Peralda, R Ticona; Varela, E; Velarde, A; Villaseñor, L; Wahl, D; Zamalloa, M A

    2009-01-01

    The Large Aperture GRB Observatory (LAGO) is aiming at the detection of the high energy (around 100 GeV) component of Gamma Ray Bursts, using the single particle technique in arrays of Water Cherenkov Detectors (WCD) in high mountain sites (Chacaltaya, Bolivia, 5300 m a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m a.s.l). WCD at high altitude offer a unique possibility of detecting low gamma fluxes in the 10 GeV - 1 TeV range. The status of the Observatory and data collected from 2007 to date will be presented.

  20. High repetition rate collisional soft x-ray lasers based on grazing incidence pumping

    Energy Technology Data Exchange (ETDEWEB)

    Luther, B M; Wang, Y; Larotonda, M A; Alessi, D; Berrill, M; Rocca, J J; Dunn, J; Keenan, R; Shlyaptsev, V N

    2005-11-18

    We discuss the demonstration of gain-saturated high repetition rate table-top soft x-ray lasers producing microwatt average powers at wavelengths ranging from 13.9 to 33 nm. The results were obtained heating a pre-created plasma with a picosecond optical laser pulse impinging at grazing incidence onto a pre-created plasma. This pumping geometry increases the energy deposition efficiency of the pump beam into the gain region, making it possible to saturate soft x-ray lasers in this wavelength range with a short pulse pump energy of only 1 J at 800 nm wavelength. Results corresponding to 5 Hz repetition rate operation of gain-saturated 14.7 nm Ni-like Pd and 32.6 nm line Ne-like Ti lasers pumped by a table-top Ti:sapphire laser are reported. We also discuss results obtained using a 1 {omega} 1054 nm pre-pulse and 2{omega} 527 nm short pulse from a Nd:glass pump laser. This work demonstrates the feasibility of producing compact high average power soft x-ray lasers for applications.

  1. Resonant Effects in Nanoscale Bowtie Apertures

    Science.gov (United States)

    Ding, Li; Qin, Jin; Guo, Songpo; Liu, Tao; Kinzel, Edward; Wang, Liang

    2016-06-01

    Nanoscale bowtie aperture antennas can be used to focus light well below the diffraction limit with extremely high transmission efficiencies. This paper studies the spectral dependence of the transmission through nanoscale bowtie apertures defined in a silver film. A realistic bowtie aperture is numerically modeled using the Finite Difference Time Domain (FDTD) method. Results show that the transmission spectrum is dominated by Fabry-Pérot (F-P) waveguide modes and plasmonic modes. The F-P resonance is sensitive to the thickness of the film and the plasmonic resonant mode is closely related to the gap distance of the bowtie aperture. Both characteristics significantly affect the transmission spectrum. To verify these numerical results, bowtie apertures are FIB milled in a silver film. Experimental transmission measurements agree with simulation data. Based on this result, nanoscale bowtie apertures can be optimized to realize deep sub-wavelength confinement with high transmission efficiency with applications to nanolithography, data storage, and bio-chemical sensing.

  2. Doppler synthetic aperture hitchhiker imaging

    International Nuclear Information System (INIS)

    In this paper we consider passive airborne receivers that use backscattered signals from sources of opportunity transmitting single-frequency or ultra-narrowband waveforms. Because of its combined passive synthetic aperture and the single-frequency nature of the transmitted waveforms, we refer to the system under consideration as Doppler synthetic aperture hitchhiker (DSAH). We present a novel image formation method for DSAH. Our method first correlates the windowed signal obtained from one receiver with the windowed, filtered, scaled and translated version of the received signal from another receiver. This processing removes the transmitter-related variables from the phase of the Fourier integral operator that maps the radiance of the scene to the correlated signal. Next, we use microlocal analysis to reconstruct the scene radiance by the weighted backprojection of the correlated signal. The image reconstruction method is applicable to both cooperative and non-cooperative sources of opportunity using one or more airborne receivers. It has the desirable property of preserving the visible edges of the scene radiance. Additionally, it is an analytic reconstruction technique that can be made computationally efficient. We present numerical simulations to demonstrate the performance of the image reconstruction method and to verify the theoretical results

  3. Advanced Multiple Aperture Seeing Profiler

    Science.gov (United States)

    Ren, Deqing; Zhao, Gang

    2016-10-01

    Measurements of the seeing profile of the atmospheric turbulence as a function of altitude are crucial for solar astronomical site characterization, as well as the optimized design and performance estimation of solar Multi-Conjugate Adaptive Optics (MCAO). Knowledge of the seeing distribution, up to 30 km, with a potential new solar observation site, is required for future solar MCAO developments. Current optical seeing profile measurement techniques are limited by the need to use a large facility solar telescope for such seeing profile measurements, which is a serious limitation on characterizing a site's seeing conditions in terms of the seeing profile. Based on our previous work, we propose a compact solar seeing profiler called the Advanced Multiple Aperture Seeing Profile (A-MASP). A-MASP consists of two small telescopes, each with a 100 mm aperture. The two small telescopes can be installed on a commercial computerized tripod to track solar granule structures for seeing profile measurement. A-MASP is extreme simple and portable, which makes it an ideal system to bring to a potential new site for seeing profile measurements.

  4. Feasibility study for an industrial superconducting table-top electron accelerator; Machbarkeitstudie fuer einen industriellen supraleitenden Table Top Elektronenbeschleuniger

    Energy Technology Data Exchange (ETDEWEB)

    Buettig, H.; Enghardt, W.; Gabriel, F.; Janssen, D.; Michel, P.; Pobell, F.; Prade, H.; Schneider, C.; Kudryavtsev, A.; Haberstroh, C.; Sandner, W.; Will, I.

    2004-07-01

    A concept of a table-top accelerator, consisting of a superconducting resonator and subsequent 6 standard TESLA cells working with a frequency of 1.3 GHz, is presented. Then electron gun is based on a photocathode. Especially described are the photocathode part, the laser system, the cryostat module, the RF system, the beam extraction, and the cryogenic facility. Finally the efficiency and the costs are considered, (HSI)

  5. Advanced Optics Experiments Using Nonuniform Aperture Functions

    CERN Document Server

    Wood, Lowell T

    2012-01-01

    A method to create instructive, nonuniform aperture functions using spatial frequency filtering is described. The diffraction from a single slit in the Fresnel limit and the interference from a double slit in the Fraunhofer limit are spatially filtered to create electric field distributions across an aperture to produce apodization, inverse apodization or super-resolution, and apertures with phase shifts across their widths. The diffraction effects from these aperture functions are measured and calculated. The excellent agreement between the experimental results and the calculated results makes the experiment ideal for use in an advanced undergraduate or graduate optics laboratory to illustrate experimentally several effects in Fourier optics.

  6. Practical Applications of Synthetic Aperture Imaging

    OpenAIRE

    Nikolov, Svetoslav Ivanov; Kortbek, Jacob; Jensen, Jørgen Arendt

    2010-01-01

    Synthetic aperture imaging has been a focus of research for almost 3 decades. The research carried out at the Center for Fast Ultrasound Imaging has demonstrated that synthetic aperture focusing not only can be used in-vivo, but that it also yields superior B-mode and blood flow images. In the last years synthetic aperture focusing has moved from the lab to commercial products. The implementations vary in their scope and purpose. Some scanners use synthetic aperture imaging to improve the det...

  7. Ion mobility spectrometer with virtual aperture grid

    Science.gov (United States)

    Pfeifer, Kent B.; Rumpf, Arthur N.

    2010-11-23

    An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.

  8. Table-top water window transmission x-ray microscopy: Review of the key issues, and conceptual design of an instrument for biology

    Science.gov (United States)

    Adam, Jean-François; Moy, Jean-Pierre; Susini, Jean

    2005-09-01

    As it has been beautifully demonstrated in synchrotron facilities, water window transmission x-ray microscopy (WW-TXM) has a great potential for high resolution three dimensional (3D) tomographic imaging of frozen cells, without the cumbersome staining and slicing preparation needed by electron microscopy. However, the existing instruments do not exactly meet the expectations of cell biologists in terms of performance and accessibility: 3D images of entire cells grown on a flat substrate with details in the 50-80nm range are necessary for structural cell studies. Functional imaging is also a key issue. Specific molecular probes are widely used to achieve molecular imaging in optical and electron microscopy. The same demand applies to x-ray microscopy. Immediate availability of the observation technique within the biology laboratory is as important as its performance. Therefore, WW-TXM will develop on a wider scale only when table-top instruments become available. We present a detailed analysis of such a microscope. The source is clearly the key element. Laser created plasmas of carbon or nitrogen are a proven but expensive solution. Cerenkov emission in vanadium has been demonstrated as a potential monochromatic source, but we emphasize severe obstacles: huge thermal load and radiation protection. We show that oxygenKα line excitation by an electron beam is a realistic alternative. Being a purely monochromatic source, it would allow the use of a high efficiency mirror condenser, while laser plasmas imply spectral selection with the associated losses. We then describe the main elements of an affordable laboratory microscope, supported by numerical simulations and preliminary experimental work. We also show that functionalized quantum dots, currently used in fluorescence microscopy, are equally detectable with soft x-rays and would allow a dual modality observation. Finally, the expected performance of this prototype is discussed and confronted by the requirements

  9. Synthetic aperture interferometry: error analysis

    International Nuclear Information System (INIS)

    Synthetic aperture interferometry (SAI) is a novel way of testing aspherics and has a potential for in-process measurement of aspherics [Appl. Opt.42, 701 (2003)].APOPAI0003-693510.1364/AO.42.000701 A method to measure steep aspherics using the SAI technique has been previously reported [Appl. Opt.47, 1705 (2008)].APOPAI0003-693510.1364/AO.47.001705 Here we investigate the computation of surface form using the SAI technique in different configurations and discuss the computational errors. A two-pass measurement strategy is proposed to reduce the computational errors, and a detailed investigation is carried out to determine the effect of alignment errors on the measurement process.

  10. Soft Ternary Semirings

    Directory of Open Access Journals (Sweden)

    S. Kar

    2016-03-01

    Full Text Available In this paper, we introduce the notion of soft ternary semiring by using the concept of soft set theory. Besides, we characterize the notions of regularity and intra-regularity in soft ternary semiring by using different soft (left, lateral, right, quasi, bi ideals of soft ternary semirings.

  11. Synthetic aperture radar: principles and applications

    International Nuclear Information System (INIS)

    In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information. (author)

  12. Towards Very Large Aperture Massive MIMO

    DEFF Research Database (Denmark)

    Oliveras Martínez, Àlex; De Carvalho, Elisabeth; Nielsen, Jesper Ødum

    2014-01-01

    on the impact of the array aperture which is the main limiting factor in the degrees of freedom available in the multiple antenna channel. We find that performance is improved as the aperture increases, with an impact mostly visible in crowded scenarios where the users are closely spaced. We also test MIMO...

  13. Practical Applications of Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav Ivanov; Kortbek, Jacob; Jensen, Jørgen Arendt

    2010-01-01

    Synthetic aperture imaging has been a focus of research for almost 3 decades. The research carried out at the Center for Fast Ultrasound Imaging has demonstrated that synthetic aperture focusing not only can be used in-vivo, but that it also yields superior B-mode and blood flow images. In the last...

  14. High Resolution Angle Resolved Photoemission with Tabletop 11eV Laser

    CERN Document Server

    He, Yu; Yi, Ming; Yang, Shuolong; Liu, Zhongkai; Lee, James; Chen, Sudi; Rebec, Slavko; Leuenberger, Dominik; Zong, Alfred; Jefferson, Michael; Moore, Robert; Kirchmann, Patrick; Merriam, Andrew; Shen, Zhixun

    2015-01-01

    We developed a table-top vacuum ultraviolet (VUV) laser with $113.778$nm wavelength (10.897eV) and demonstrated its viability as a photon source for high resolution angle-resolved photoemission spectroscopy (ARPES). This sub-nanosecond pulsed VUV laser operates at a repetition rate of 10MHz, provides a flux of 2$\\times$10$^{12}$ photons/second, and enables photoemission with energy and momentum resolutions better than 2meV and 0.012\\AA$^{-1}$, respectively. Space-charge induced energy shifts and spectral broadenings can be reduced below 2meV. The setup reaches electron momenta up to 1.2\\AA$^{-1}$, granting full access to the first Brillouin zone of most materials. Control over the linear polarization, repetition rate, and photon flux of the VUV source facilitates ARPES investigations of a broad range of quantum materials, bridging the application gap between contemporary low energy laser-based ARPES and synchrotron-based ARPES. We describe the principles and operational characteristics of this source, and sho...

  15. Ultrafast element-specific magnetization dynamics of complex magnetic materials on a table-top

    Energy Technology Data Exchange (ETDEWEB)

    Mathias, Stefan, E-mail: smathias@physik.uni-kl.de [University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern (Germany); Department of Physics and JILA, University of Colorado and NIST, Boulder, CO, 80309 (United States); La-o-vorakiat, Chan [Department of Physics and JILA, University of Colorado and NIST, Boulder, CO, 80309 (United States); Shaw, Justin M. [Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO, 80305 (United States); Turgut, Emrah [Department of Physics and JILA, University of Colorado and NIST, Boulder, CO, 80309 (United States); Grychtol, Patrik [Department of Physics and JILA, University of Colorado and NIST, Boulder, CO, 80309 (United States); Peter Grünberg Institut PGI-6 and JARA-FIT, Research Centre Jülich, 52425 Jülich (Germany); Adam, Roman; Rudolf, Dennis [Peter Grünberg Institut PGI-6 and JARA-FIT, Research Centre Jülich, 52425 Jülich (Germany); Nembach, Hans T.; Silva, Thomas J. [Electromagnetics Division, National Institute of Standards and Technology, Boulder, CO, 80305 (United States); Aeschlimann, Martin [University of Kaiserslautern and Research Center OPTIMAS, 67663 Kaiserslautern (Germany); Schneider, Claus M. [Peter Grünberg Institut PGI-6 and JARA-FIT, Research Centre Jülich, 52425 Jülich (Germany); Kapteyn, Henry C.; Murnane, Margaret M. [Department of Physics and JILA, University of Colorado and NIST, Boulder, CO, 80309 (United States)

    2013-08-15

    Highlights: ► We use X-ray pulses from high-harmonic generation to study element-specific magnetic dynamics. ► We elucidate the timescale of the exchange interaction in multi-sublattice magnets. ► Ultrafast superdiffusive spin currents induce femtosecond magnetization dynamics. -- Abstract: We review recent progress in femtosecond magnetization dynamics probed by extreme ultraviolet pulses from high-harmonic generation. In a transverse magneto-optical Kerr geometry, we established an ultrafast, element-specific experimental capability – on a table-top – for the measurement of magnetization dynamics in complex multi-sublattice magnets and multilayer magnetic structures. We show that this newly introduced technique is an artifact-free magnetic sensor, with only negligible non-magnetic (optical) contributions from the transient variation of the refractive index due to the presence of a non equilibrium hot-electron distribution. We then use these new experimental capabilities of ultrahigh time-resolution, combined with element-specific simultaneous probing, to disentangle important microscopic processes that drive magnetization dynamics on femtosecond timescales. We elucidate the role of exchange interaction on magnetization dynamics in strongly exchange-coupled alloys, and the role of photo-induced superdiffusive spin currents in magnetic multilayer stacks.

  16. TangiWheel: A Widget for Manipulating Collections on Tabletop Displays Supporting Hybrid Input Modality

    Institute of Scientific and Technical Information of China (English)

    Alejandro Catalá; Fernando Garcia-Sanjuan; Javier Jaen; Jose A.Mocholi

    2012-01-01

    In this paper we present TangiWheel,a collection manipulation widget for tabletop displays.Our implementation is flexible,allowing either multi-touch or interaction,or even a hybrid scheme to better suit user choice and convenience.Different TangiWheel aspects and features are compared with other existing widgets for collection manipulation.The study reveals that TangiWheel is the first proposal to support a hybrid input modality with large resemblance levels between touch and tangible interaction styles.Several experiments were conducted to evaluate the techniques used in each input scheme for a better understanding of tangible surface interfaces in complex tasks performed by a single user (e.g.,involving a typical master-slave exploration pattern).The results show that tangibles perform significantly better than fingers,despite dealing with a greater number of interactions,in situations that require a large number of acquisitions and basic manipulation tasks such as establishing location and orientation.However,when users have to perform multiple exploration and selection operations that do not require previous basic manipulation tasks,for instance when collections are fixed in the interface layout,touch input is significantly better in terms of required time and number of actions.Finally,when a more elastic collection layout or more complex additional insertion or displacement operations are needed,the hybrid and tangible approaches clearly outperform finger-based interactions.

  17. Invited Article: High resolution angle resolved photoemission with tabletop 11 eV laser

    Energy Technology Data Exchange (ETDEWEB)

    He, Yu; Vishik, Inna M.; Yi, Ming; Yang, Shuolong; Lee, James J.; Chen, Sudi; Rebec, Slavko N.; Leuenberger, Dominik; Shen, Zhi-Xun [SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Liu, Zhongkai [SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Zong, Alfred [Department of Physics, Stanford University, Stanford, California 94305 (United States); Jefferson, C. Michael; Merriam, Andrew J. [Lumeras LLC, 207 McPherson St, Santa Cruz, California 95060 (United States); Moore, Robert G.; Kirchmann, Patrick S. [SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-01-15

    We developed a table-top vacuum ultraviolet (VUV) laser with 113.778 nm wavelength (10.897 eV) and demonstrated its viability as a photon source for high resolution angle-resolved photoemission spectroscopy (ARPES). This sub-nanosecond pulsed VUV laser operates at a repetition rate of 10 MHz, provides a flux of 2 × 10{sup 12} photons/s, and enables photoemission with energy and momentum resolutions better than 2 meV and 0.012 Å{sup −1}, respectively. Space-charge induced energy shifts and spectral broadenings can be reduced below 2 meV. The setup reaches electron momenta up to 1.2 Å{sup −1}, granting full access to the first Brillouin zone of most materials. Control over the linear polarization, repetition rate, and photon flux of the VUV source facilitates ARPES investigations of a broad range of quantum materials, bridging the application gap between contemporary low energy laser-based ARPES and synchrotron-based ARPES. We describe the principles and operational characteristics of this source and showcase its performance for rare earth metal tritellurides, high temperature cuprate superconductors, and iron-based superconductors.

  18. Invited Article: High resolution angle resolved photoemission with tabletop 11 eV laser.

    Science.gov (United States)

    He, Yu; Vishik, Inna M; Yi, Ming; Yang, Shuolong; Liu, Zhongkai; Lee, James J; Chen, Sudi; Rebec, Slavko N; Leuenberger, Dominik; Zong, Alfred; Jefferson, C Michael; Moore, Robert G; Kirchmann, Patrick S; Merriam, Andrew J; Shen, Zhi-Xun

    2016-01-01

    We developed a table-top vacuum ultraviolet (VUV) laser with 113.778 nm wavelength (10.897 eV) and demonstrated its viability as a photon source for high resolution angle-resolved photoemission spectroscopy (ARPES). This sub-nanosecond pulsed VUV laser operates at a repetition rate of 10 MHz, provides a flux of 2 × 10(12) photons/s, and enables photoemission with energy and momentum resolutions better than 2 meV and 0.012 Å(-1), respectively. Space-charge induced energy shifts and spectral broadenings can be reduced below 2 meV. The setup reaches electron momenta up to 1.2 Å(-1), granting full access to the first Brillouin zone of most materials. Control over the linear polarization, repetition rate, and photon flux of the VUV source facilitates ARPES investigations of a broad range of quantum materials, bridging the application gap between contemporary low energy laser-based ARPES and synchrotron-based ARPES. We describe the principles and operational characteristics of this source and showcase its performance for rare earth metal tritellurides, high temperature cuprate superconductors, and iron-based superconductors. PMID:26827301

  19. FTIR determination of Aspartame and Acesulfame-K in tabletop sweeteners.

    Science.gov (United States)

    Armenta, Sergio; Garrigues, Salvador; de la Guardia, Miguel

    2004-12-29

    Two different strategies for sweeteners determination in tabletop samples by Fourier transform middle-infrared (FTIR) spectrometry, an off-line and a fully mechanized extraction of Aspartame and Acesulfame-K with different mixtures of chloroform and methanol, have been developed. The off-line method involves the extraction of both active principles by sonication of samples with 25:75 v/v CHCl3/CH3OH and direct measurement of the peak height values at 1751 cm(-1), corrected using a baseline defined at 1850 cm(-1) for Aspartame, and measurement of the peak height at 1170 cm(-1) in the first-order derivative spectra, corrected by using a horizontal baseline established at 1850 cm(-1), for Acesulfame-K. Limit of detection values of 0.10 and 0.9% w/w and relative standard deviations of 0.17 and 0.5% were found for Aspartame and Acesulfame-K, respectively. The time needed for the sweeteners determination is reduced from 35 min for the HPLC method to 7 min by FTIR. On the other hand, the fully mechanized on-line extraction avoids the contact of the operator with toxic solvents and differentiates between samples that contain Aspartame and Acesulfame-K and those that include only Aspartame, reducing the time needed for the analysis of the last kind of samples to 5 min. PMID:15612758

  20. Ultrafast Time-Resolved Hard X-Ray Emission Spectroscopy on a Tabletop

    Science.gov (United States)

    Miaja-Avila, Luis; O'Neil, Galen C.; Joe, Young I.; Alpert, Bradley K.; Damrauer, Niels H.; Doriese, William B.; Fatur, Steven M.; Fowler, Joseph W.; Hilton, Gene C.; Jimenez, Ralph; Reintsema, Carl D.; Schmidt, Daniel R.; Silverman, Kevin L.; Swetz, Daniel S.; Tatsuno, Hideyuki; Ullom, Joel N.

    2016-07-01

    Experimental tools capable of monitoring both atomic and electronic structure on ultrafast (femtosecond to picosecond) time scales are needed for investigating photophysical processes fundamental to light harvesting, photocatalysis, energy and data storage, and optical display technologies. Time-resolved hard x-ray (>3 keV ) spectroscopies have proven valuable for these measurements due to their elemental specificity and sensitivity to geometric and electronic structures. Here, we present the first tabletop apparatus capable of performing time-resolved x-ray emission spectroscopy. The time resolution of the apparatus is better than 6 ps. By combining a compact laser-driven plasma source with a highly efficient array of microcalorimeter x-ray detectors, we are able to observe photoinduced spin changes in an archetypal polypyridyl iron complex [Fe (2 ,2'-bipyridine)3]2 + and accurately measure the lifetime of the quintet spin state. Our results demonstrate that ultrafast hard x-ray emission spectroscopy is no longer confined to large facilities and now can be performed in conventional laboratories with 10 times better time resolution than at synchrotrons. Our results are enabled, in part, by a 100- to 1000-fold increase in x-ray collection efficiency compared to current techniques.

  1. Observation of iron spin-states using tabletop x-ray emission spectroscopy and microcalorimeter sensors

    Science.gov (United States)

    Joe, Y. I.; O'Neil, G. C.; Miaja-Avila, L.; Fowler, J. W.; Jimenez, R.; Silverman, K. L.; Swetz, D. S.; Ullom, J. N.

    2016-01-01

    X-ray emission spectroscopy (XES) is a powerful probe of the electronic and chemical state of elemental species embedded within complex compounds. X-ray sensors that combine high resolving power and high collecting efficiency are desirable for photon-starved XES experiments such as measurements of dilute, gaseous, and radiation-sensitive samples, time-resolved measurements, and in-laboratory XES. To assess whether arrays of cryogenic microcalorimeters will be useful in photon-starved XES scenarios, we demonstrate that these emerging energy-dispersive sensors can detect the spin-state of 3d electrons of iron in two different compounds, Fe2O3 and FeS2. The measurements were conducted with a picosecond pulsed laser-driven plasma as the exciting x-ray source. The use of this tabletop source suggests that time-resolved in-laboratory XES will be possible in the future. We also present simulations of {{K}}α and {{K}}β spectra that reveal the spin-state sensitivity of different combinations of sensor resolution and accumulated counts. These simulations predict that our current experimental apparatus can perform time-resolved XES measurements on some samples with a measurement time of a few 10 s of hours per time delay.

  2. Thermal emission by a subwavelength aperture

    Science.gov (United States)

    Joulain, Karl; Ezzahri, Younès; Carminati, Rémi

    2016-04-01

    We calculate, by means of fluctuational electrodynamics, the thermal emission of an aperture separating from the outside, vacuum or a material at temperature T. We show that thermal emission is very different whether the aperture size is large or small compared to the thermal wavelength. Subwavelength apertures separating vacuum from the outside have their thermal emission strongly decreased compared to classical blackbodies which have an aperture much larger than the wavelength. A simple expression of their emissivity can be calculated and their total emissive power scales as T8 instead of T4 for large apertures. Thermal emission of disk of materials with a size comparable to the wavelength is also discussed. It is shown in particular that emissivity of such a disk is increased when the material can support surface waves such as phonon polaritons.

  3. Soft Interfaces

    Science.gov (United States)

    Gilles de Gennes, Pierre; Edwards, Introduction By Sam

    1997-04-01

    Paul Adrien Maurice Dirac, one of the greatest physicists of the twentieth century, died in 1984. Dirac's college, St. John's of Cambridge, generously endowed annual lectures to be held at Cambridge University in his memory. This volume contains a much expanded version of the 1994 Dirac Lecture by Nobel Laureate Pierre Gilles de Gennes. The book presents an impressionistic tour of the physics of soft interfaces. Full of insight and interesting asides, it not only provides an accessible introduction to this topic, but also lays down many markers and signposts that will be of interest to researchers in physics or chemistry. Features discussions of wetting and dewetting, the dynamics of different types of interface and adhesion and polymer/polymer welding.

  4. Adult soft tissue sarcoma

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/007654.htm Adult soft tissue sarcoma To use the sharing features on this page, please enable JavaScript. Soft tissue sarcoma is cancer that forms in the soft ...

  5. Necrotizing soft tissue infection

    Science.gov (United States)

    Necrotizing fasciitis; Fasciitis - necrotizing; Flesh-eating bacteria; Soft tissue gangrene; Gangrene - soft tissue ... severe and usually deadly form of necrotizing soft tissue infection is due to the bacteria Streptococcus pyogenes , ...

  6. Wide-aperture electric-discharge nitrogen laser

    International Nuclear Information System (INIS)

    The parameters of a wide-aperture nitrogen laser pumped by a generator with the inductive energy storage and a SOS diode opening switch or a generator with the capacitive energy storage are studied. The gas preionisation was performed by soft X-rays. The size of the active volume of the laser was 10x6x100 cm. The output energy and power obtained at the 337.1-nm C 3Πu - B 3Πg transition are maximal for electric-discharge nitrogen lasers. The output energy in the second positive system of nitrogen in the N2-SF6 mixture achieved 110 mJ for a peak power of 6 MW. Due to an increase in voltage across the laser gap in nitrogen mixtures with NF3, the generation of ∼35-mJ, 100-ns pulses was obtained in the quasi-stationary stage of the discharge. (lasers)

  7. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

    Science.gov (United States)

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

    2015-11-17

    We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

  8. Directional synthetic aperture flow imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav

    2004-01-01

    . A plastic tube with an internal diameter of 17 mm was used with an EcoWatt 1 pump generating a laminar, stationary flow. The velocity profile was measured for flow angles of 90 and 60 degrees. The RASMUS research scanner was used for acquiring RF data from 128 elements of the array using 8 emissions with 11...... elements in each emission. A 20 us chirp was used during emission. The RF data were subsequently beamformed off-line and stationary echo canceling was performed. The 60 degrees flow with a peak velocity of 0.15 m/s was determined using 16 groups of 8 emissions and the relative standard deviation was 0......A method for flow estimation using synthetic aperture imaging and focusing along the flow direction is presented. The method can find the correct velocity magnitude for any flow angle and full color flow images can be measured using only 32 to 128 pulse emissions. The approach uses spherical wave...

  9. Fast Parametric Beamformer for Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev

    2008-01-01

    This paper describes the design and implementation of a real-time delay-and-sum synthetic aperture beamformer. The beamforming delays and apodization coefficients are described parametrically. The image is viewed as a set of independent lines that are defined in 3-D by their origin, direction, and...... implementation of the beamformer is optimized with respect to the architecture of a novel synthetic aperture real-time ultrasound scanner (SARUS), in which 4 channels are processed by the same set of field-programmable gate arrays (FPGA). In synthetic transmit aperture imaging, low-resolution images are formed...

  10. Three dimensional digital holographic aperture synthesis.

    Science.gov (United States)

    Crouch, Stephen; Kaylor, Brant M; Barber, Zeb W; Reibel, Randy R

    2015-09-01

    Aperture synthesis techniques are applied to temporally and spatially diverse digital holograms recorded with a fast focal-plane array. Because the technique fully resolves the downrange dimension using wide-bandwidth FMCW linear-chirp waveforms, extremely high resolution three dimensional (3D) images can be obtained even at very long standoff ranges. This allows excellent 3D image formation even when targets have significant structure or discontinuities, which are typically poorly rendered with multi-baseline synthetic aperture ladar or multi-wavelength holographic aperture ladar approaches. The background for the system is described and system performance is demonstrated through both simulation and experiments. PMID:26368474

  11. Highly Efficient Tabletop Optical Parametric Chirped Pulse Amplifier at 1 (micron)m

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, I.; Ebbers, C.A.; Comaskey, B.J.; Bonner, R.A.; Morse, E.C.

    2001-12-04

    Optical parametric chirped pulse amplification (OPCPA) is a scalable technology, for ultrashort pulse amplification. Its major advantages include design simplicity, broad bandwidth, tunability, low B-integral, high contrast, and high beam quality. OPCPA is suitable both for scaling to high peak power as well as high average power. We describe the amplification of stretched 100 fs oscillator pulses in a three-stage OPCPA system pumped by a commercial, single-longitudinal-mode, Q-switched Nd:YAG laser. The stretched pulses were centered around 1054 nm with a FWHM bandwidth of 16.5 nm and had an energy of 0.5 nJ. Using our OPCPA system, we obtained an amplified pulse energy of up to 31 mJ at a 10 Hz repetition rate. The overall conversion efficiency from pump to signal is 6%, which is the highest efficiency obtained With a commercial tabletop pump laser to date. The overall conversion efficiency is limited due to the finite temporal overlap of the seed (3 ns) with respect to the duration of the pump (8.5 ns). Within the temporal window of the seed pulse the pump to signal conversion efficiency exceeds 20%. Recompression of the amplified signal was demonstrated to 310 fs, limited by the aberrations initially present in the low energy seed imparted by the pulse stretcher. The maximum gain in our OPCPA system is 6 x 10{sup 7}, obtained through single passing of 40 mm of beta-barium borate. We present data on the beam quality obtained from our system (M{sup 2}=1.1). This relatively simple system replaces a significantly more complex Ti:sapphire regenerative amplifier based CPA system used in the front end of a high energy short pulse laser. Future improvement will include obtaining shorter amplified pulses and higher average power.

  12. Integrating biologically inspired nanomaterials and table-top stereolithography for 3D printed biomimetic osteochondral scaffolds.

    Science.gov (United States)

    Castro, Nathan J; O'Brien, Joseph; Zhang, Lijie Grace

    2015-09-01

    The osteochondral interface of an arthritic joint is notoriously difficult to regenerate due to its extremely poor regenerative capacity and complex stratified architecture. Native osteochondral tissue extracellular matrix is composed of numerous nanoscale organic and inorganic constituents. Although various tissue engineering strategies exist in addressing osteochondral defects, limitations persist with regards to tissue scaffolding which exhibit biomimetic cues at the nano to micro scale. In an effort to address this, the current work focused on 3D printing biomimetic nanocomposite scaffolds for improved osteochondral tissue regeneration. For this purpose, two biologically-inspired nanomaterials have been synthesized consisting of (1) osteoconductive nanocrystalline hydroxyapatite (nHA) (primary inorganic component of bone) and (2) core-shell poly(lactic-co-glycolic) acid (PLGA) nanospheres encapsulated with chondrogenic transforming growth-factor β1 (TGF-β1) for sustained delivery. Then, a novel table-top stereolithography 3D printer and the nano-ink (i.e., nHA + nanosphere + hydrogel) were employed to fabricate a porous and highly interconnected osteochondral scaffold with hierarchical nano-to-micro structure and spatiotemporal bioactive factor gradients. Our results showed that human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and osteochondral differentiation were greatly improved in the biomimetic graded 3D printed osteochondral construct in vitro. The current work served to illustrate the efficacy of the nano-ink and current 3D printing technology for efficient fabrication of a novel nanocomposite hydrogel scaffold. In addition, tissue-specific growth factors illustrated a synergistic effect leading to increased cell adhesion and directed stem cell differentiation.

  13. Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device

    Science.gov (United States)

    Rout, R. K.; Mishra, P.; Rawool, A. M.; Kulkarni, L. V.; Gupta, Satish C.

    2008-10-01

    The development of a novel and portable tabletop pulsed neutron source is presented. It is a battery powered neutron tube based on a miniature plasma focus (PF) device having all metal-sealed components. The tube, fuelled with deuterium gas, generates neutrons because of D-D fusion reactions. The inner diameter and the length of the tube are 3.4 cm and 8 cm, respectively. A single capacitor (200 J, 4.0 µF, 10 nH) of compact size (17 cm × 15 cm × 13 cm, 6.5 kg) is used as the energy driver. A power supply system charges the capacitor to 10 kV in 10 s and also provides a 30 kV trigger pulse to the spark gap. An input of 24 V dc (7.5 A) to the power supply system is provided by two rechargeable batteries (each 12 V, 7.5 A, 20 h). The device has produced neutrons for 150 shots within a period of 120 days in a very reliable manner without purging the deuterium gas between the shots. For the first 50 shots, the average yield is (1.6 ± 0.3) × 106 neutrons/shot in 4π sr with a pulse width of 23.4 ± 3.3 ns. The estimated neutron energy is 2.47 ± 0.22 MeV. The neutron production reduces slowly and reaches the detection threshold value of 3 × 105 neutrons/shot towards the last shots. The device produces neutrons in a similar manner on evacuation and refilling. The height of the mounted PF tube with the capacitor and the spark gap is 35 cm. The complete setup comprising the capacitor with spark gap, the PF tube, the power supply system with two batteries and the control panel weighs only 23 kg.

  14. Integrating biologically inspired nanomaterials and table-top stereolithography for 3D printed biomimetic osteochondral scaffolds.

    Science.gov (United States)

    Castro, Nathan J; O'Brien, Joseph; Zhang, Lijie Grace

    2015-09-01

    The osteochondral interface of an arthritic joint is notoriously difficult to regenerate due to its extremely poor regenerative capacity and complex stratified architecture. Native osteochondral tissue extracellular matrix is composed of numerous nanoscale organic and inorganic constituents. Although various tissue engineering strategies exist in addressing osteochondral defects, limitations persist with regards to tissue scaffolding which exhibit biomimetic cues at the nano to micro scale. In an effort to address this, the current work focused on 3D printing biomimetic nanocomposite scaffolds for improved osteochondral tissue regeneration. For this purpose, two biologically-inspired nanomaterials have been synthesized consisting of (1) osteoconductive nanocrystalline hydroxyapatite (nHA) (primary inorganic component of bone) and (2) core-shell poly(lactic-co-glycolic) acid (PLGA) nanospheres encapsulated with chondrogenic transforming growth-factor β1 (TGF-β1) for sustained delivery. Then, a novel table-top stereolithography 3D printer and the nano-ink (i.e., nHA + nanosphere + hydrogel) were employed to fabricate a porous and highly interconnected osteochondral scaffold with hierarchical nano-to-micro structure and spatiotemporal bioactive factor gradients. Our results showed that human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and osteochondral differentiation were greatly improved in the biomimetic graded 3D printed osteochondral construct in vitro. The current work served to illustrate the efficacy of the nano-ink and current 3D printing technology for efficient fabrication of a novel nanocomposite hydrogel scaffold. In addition, tissue-specific growth factors illustrated a synergistic effect leading to increased cell adhesion and directed stem cell differentiation. PMID:26234364

  15. Integrating biologically inspired nanomaterials and table-top stereolithography for 3D printed biomimetic osteochondral scaffolds

    Science.gov (United States)

    Castro, Nathan J.; O'Brien, Joseph; Zhang, Lijie Grace

    2015-08-01

    The osteochondral interface of an arthritic joint is notoriously difficult to regenerate due to its extremely poor regenerative capacity and complex stratified architecture. Native osteochondral tissue extracellular matrix is composed of numerous nanoscale organic and inorganic constituents. Although various tissue engineering strategies exist in addressing osteochondral defects, limitations persist with regards to tissue scaffolding which exhibit biomimetic cues at the nano to micro scale. In an effort to address this, the current work focused on 3D printing biomimetic nanocomposite scaffolds for improved osteochondral tissue regeneration. For this purpose, two biologically-inspired nanomaterials have been synthesized consisting of (1) osteoconductive nanocrystalline hydroxyapatite (nHA) (primary inorganic component of bone) and (2) core-shell poly(lactic-co-glycolic) acid (PLGA) nanospheres encapsulated with chondrogenic transforming growth-factor β1 (TGF-β1) for sustained delivery. Then, a novel table-top stereolithography 3D printer and the nano-ink (i.e., nHA + nanosphere + hydrogel) were employed to fabricate a porous and highly interconnected osteochondral scaffold with hierarchical nano-to-micro structure and spatiotemporal bioactive factor gradients. Our results showed that human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and osteochondral differentiation were greatly improved in the biomimetic graded 3D printed osteochondral construct in vitro. The current work served to illustrate the efficacy of the nano-ink and current 3D printing technology for efficient fabrication of a novel nanocomposite hydrogel scaffold. In addition, tissue-specific growth factors illustrated a synergistic effect leading to increased cell adhesion and directed stem cell differentiation.

  16. MTF analysis of a prototype table-top inverse-geometry volumetric CT system

    Science.gov (United States)

    Schmidt, Taly G.; Bennett, N. Robert; Mazin, Samuel R.; Star-Lack, Josh; Solomon, Edward G.; Pelc, Norbert J.

    2005-04-01

    This work investigates the modulation transfer function (MTF) of a prototype table-top inverse-geometry volumetric CT (IGCT) system. The IGCT system has been proposed to acquire sufficient volumetric data in one circular rotation using a large-area scanned source and a narrower array of fast detectors. The source and detector arrays have the same axial, or slice, extent, thus providing sufficient volumetric coverage. A prototype system has been built using a NexRay Scanning-Beam Digital X-ray system (NexRay, Inc., Los Gatos, CA) with the C-arm gantry in the horizontal position and a stage placed between the source and detector to rotate the scanned object. The resulting system has a 16-cm in-plane field of view (FOV) and 5-cm axial FOV. Two phantoms were constructed for measuring the MTF. A 76 micron tungsten wire placed axially in a plastic frame was used to measure the in-plane MTF, and the same wire slanted at 45 degrees was used to test the isotropy of the MTF. The data were calibrated for flat-field intensity and geometric misalignment and reconstructed using a modified 3D PET algorithm. For both phantoms, slices perpendicular to the wires were reconstructed. Simulations which model the IGCT system were used to verify the MTF measurement, along with analytical predictions. The measured MTF curve was similar in shape to the predicted curve with a 10% point at 20 lp/cm compared to a predicted 18 lp/cm. Future work will also study the uniformity of the MTF across the FOV and further characterize the IGCT system.

  17. Soft Interfaces

    International Nuclear Information System (INIS)

    This book presents an extended form of the 1994 Dirac Memorial Lecture delivered by Pierre Gilles de Gennes at Cambridge University. The main task of the presentation is to show the beauty and richness of structural forms and phenomena which are observed at soft interfaces between two media. They are much more complex than forms and phenomena existing in each phase separately. Problems are discussed including both traditional, classical techniques, such as the contact angle in static and dynamic partial wetting, as well as the latest research methodology, like 'environmental' scanning electron microscopes. The book is not a systematic lecture on phenomena but it can be considered as a compact set of essays on topics which particularly fascinate the author. The continuum theory widely used in the book is based on a deep molecular approach. The author is particularly interested in a broad-minded rheology of liquid systems at interfaces with specific emphasis on polymer melts. To study this, the author has developed a special methodology called anemometry near walls. The second main topic presented in the book is the problem of adhesion. Molecular processes, energy transformations and electrostatic interaction are included in an interesting discussion of the many aspects of the principles of adhesion. The third topic concerns welding between two polymer surfaces, such as A/A and A/B interfaces. Of great worth is the presentation of various unsolved, open problems. The kind of topics and brevity of description indicate that this book is intended for a well prepared reader. However, for any reader it will present an interesting picture of how many mysterious processes are acting in the surrounding world and how these phenomena are perceived by a Nobel Laureate, who won that prize mainly for his investigations in this field. (book review)

  18. Synthetic Aperture Radar Missions Study Report

    Science.gov (United States)

    Bard, S.

    2000-01-01

    This report reviews the history of the LightSAR project and summarizes actions the agency can undertake to support industry-led efforts to develop an operational synthetic aperture radar (SAR) capability in the United States.

  19. Beam Combination for Sparse Aperture Telescopes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for funding to continue development of an alternative beam combiner for Stellar Imager (SI), a 30-aperture, interferometric telescope chosen as one...

  20. Thermal Emission by a Subwavelength Aperture

    CERN Document Server

    Joulain, Karl; Carminati, Rémi

    2015-01-01

    We calculate, by means of fluctuational electrodynamics, the thermal emission of an aperture filled by vacuum or a material at temperature T. We show that thermal emission is very different whether the aperture size is large or small compared to the thermal wavelength. Subwavelength apertures filled with vacuum (subwavelength blackbody) have their thermal emission strongly decreased compared to classical blackbodies. A simple expression of their emissivity can be calculated and their total emittance scales as T 8 instead of T 4 for large apertures. Thermal emission of disk of materials with a size comparable to the wavelength is also discussed. It is shown in particular that emissivity of such a disk is increased when the material can support surface waves such as phonon polaritons.

  1. Synthetic Aperture Techniques for Sonar Systems

    OpenAIRE

    Silva, S&#;rgio Rui; Cunha, S&#;rgio; Matos, An&#;bal; Cruz, Nuno

    2009-01-01

    As demonstrated, synthetic aperture sonar is a technique that enables attainment of high quality, high resolution underwater images. Autonomous surface vehicles provides several advantages for synthetic aperture imagery. Not only it is possible to control the boat motion in this way, it is also possible to obtain navigation measurements with precisions in the order of the wavelength used in high resolution sonar systems. Furthermore unsupervised surveillance applications that combine the high...

  2. An autonomous boat based Synthetic Aperture Sonar

    OpenAIRE

    Sergio Rui Silva; Sergio Cunha; Anibal Matos; Nuno Cruz

    2007-01-01

    This paper describes a Synthetic Aperture Sonar (SAS) system being developed at the University of Porto to be used in a small autonomous boat for the survey of shallow water environments, such as rivers, deltas, estuaries and dams. Its purpose is to obtain high resolution echo reflectivity maps through synthetic aperture techniques, taking advantage of the high precision navigation system of the boat. In the future the production of bottom tomography maps is also considered through the use of...

  3. Biomineral repair of Abalone shell apertures

    OpenAIRE

    Cusack, M.; Guo, D.; Chung, P.; Kamenos, N. A.

    2013-01-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, ...

  4. Resonant Effects in Nanoscale Bowtie Apertures

    Science.gov (United States)

    Ding, Li; Qin, Jin; Guo, Songpo; Liu, Tao; Kinzel, Edward; Wang, Liang

    2016-01-01

    Nanoscale bowtie aperture antennas can be used to focus light well below the diffraction limit with extremely high transmission efficiencies. This paper studies the spectral dependence of the transmission through nanoscale bowtie apertures defined in a silver film. A realistic bowtie aperture is numerically modeled using the Finite Difference Time Domain (FDTD) method. Results show that the transmission spectrum is dominated by Fabry-Pérot (F-P) waveguide modes and plasmonic modes. The F-P resonance is sensitive to the thickness of the film and the plasmonic resonant mode is closely related to the gap distance of the bowtie aperture. Both characteristics significantly affect the transmission spectrum. To verify these numerical results, bowtie apertures are FIB milled in a silver film. Experimental transmission measurements agree with simulation data. Based on this result, nanoscale bowtie apertures can be optimized to realize deep sub-wavelength confinement with high transmission efficiency with applications to nanolithography, data storage, and bio-chemical sensing. PMID:27250995

  5. Brainstorming und Mind-Mapping im Multi-Device-Kontext. Konzeption und prototypische Implementierung für Multi-Touch-Tabletop und Smartphone

    OpenAIRE

    Will, Sarah

    2013-01-01

    Die vorliegende Arbeit beschreibt die Konzeption und prototypische Implemen­tierung einer Anwendung zur elektronischen Unterstützung von Brainstorming- und Mind-Mapping-Sitzungen an einem multitouchfähigen Tabletop mit Smart­phones. Während der Tabletop durch seine große, horizontal ausgerichtete Oberfläche die kollaborative Erstellung und Strukturierung von Ideen in Gruppen unterstützt, werden Smartphones einen zusätzlichen Eingabekanal zur Verfügung stellen sowie Individualarbeit fördern. S...

  6. Fuzzy Soft Topological Groups

    Directory of Open Access Journals (Sweden)

    S. Nazmul

    2014-03-01

    Full Text Available Notions of Lowen type fuzzy soft topological space are introduced and some of their properties are established in the present paper. Besides this, a combined structure of a fuzzy soft topological space and a fuzzy soft group, which is termed here as fuzzy soft topological group is introduced. Homomorphic images and preimages are also examined. Finally, some definitions and results on fuzzy soft set are studied.

  7. A table-top x-ray FEL based on a laser wakefield accelerator-undulator system

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, K.; Kawakubo, T.; Nakanishi, H. [National Lab. for High Energy Physics, Ibaraki-ken (Japan)] [and others

    1995-12-31

    Ultrahigh-gradient electron acceleration has been confirmed owing to the laser wakefield acceleration mechanism driven by an intense short laser wakefield acceleration mechanism driven by an intense short laser pulse in an underdense plasma. The laser wakefield acceleration makes it possible to build a compact electron linac capable of producing an ultra-short bunched electron beam. While the accelerator is attributed to longitudinal wakefields, transverse wakefields simultaneously generated by a short laser pulse can serve as a plasma undulator with a very short wavelength equal to a half of the plasma wavelength. We propose a new FEL concept for X-rays based on a laser wakefield accelerator-undulator system driven by intense short laser pulses delivered from table-top terawatt lasers. The system is composed of the accelerator stage and the undulator stage in a table-top size. A low energy electron beam is accelerated an bunched into microbunches due to laser wakefields in the accelerator stage. A micro-bunched beam travelling to the opposite direction of driving laser pulses produces coherent X-ray radiation in the undulator stage. A practical configuration and its analyses are presented.

  8. Concepts, performance review, and prospects of table-top, few-cycle optical parametric chirped-pulse amplification

    Science.gov (United States)

    Vaupel, Andreas; Bodnar, Nathan; Webb, Benjamin; Shah, Lawrence; Richardson, Martin

    2014-05-01

    More than 20 years after the first presentation of optical parametric chirped-pulse amplification (OPCPA), the technology has matured as a powerful technique to produce high-intensity, few-cycle, and ultrashort laser pulses. The output characteristics of these systems cover a wide range of center wavelengths, pulse energies, and average powers. The current record performance of table-top, few-cycle OPCPA systems are 16 TW peak power and 22 W average power, which show that OPCPA is able to directly compete with Ti:sapphire chirped-pulse amplification-based systems as source for intense optical pulses. Here, we review the concepts of OPCPA and present the current state-of-the art performance level for several systems reported in the literature. To date, the performance of these systems is most generally limited by the employed pump laser. Thus, we present a comprehensive review on the recent progress in high-energy, high-average-power, picosecond laser systems, which provide improved performance relative to OPCPA pump lasers employed to date. From here, the impact of these novel pump lasers on table-top, few-cycle OPCPA is detailed and the prospects for next-generation OPCPA systems are discussed.

  9. Tabletop demonstration of non-Interaction of photons and non-interference of waves

    Science.gov (United States)

    Prasad, Narasimha S.; Roychoudhuri, Chandra

    2015-09-01

    Recently, Non- Interaction of Waves or the NIW property has been proposed as a generic property of all propagating electromagnetic waves by one of the authors (CR). In other words, optical beams do not interact with each other to modify or re-distribute their field energy distribution in the absence of interacting materials. In this paper, path taken to re-create CR's original demonstration of the NIW-property as an on-site tabletop experiment is discussed. Since 1975, when the NIW demonstration was first reported, several advances in lasers and optical component design architecture have occurred. With the goal of using low cost components and having agility in setting up on non-conformable platforms for general viewing, a compact arrangement for demonstrating the NIW property was envisioned. In our experimental arrangement, a beam multiplier element was utilized to generate a set of spatially separate parallel beams out of an incident laser beam. The emerging parallel beams from the beam multiplier element were then focused on a one-sided ground glass, the flat side being towards the beam multiplier. This flat side reflects off all the incident focused beams as fanning out independent laser beams, remaining unperturbed even though they are reflecting out of a common superposed spot. It is clear that there is neither "interference between different photons", nor "a photon interferes with itself", even within a region of superposed beams. In contrast, the ground glass surface (same silica molecules but granular or lumpy) was anticipated to generate a set of crisp spatial fringes on its surface as in the original experiment. The fringes are due to granulated individual silica lumps responding simultaneously to the local resultant E-vectors due to all the superposed beams and are scattering energy proportional to the square modulus of the sum of all the simultaneous dipolar amplitude stimulations. The dark fringe locations imply zero resultant amplitude stimulation

  10. Aperture effects in squid jet propulsion.

    Science.gov (United States)

    Staaf, Danna J; Gilly, William F; Denny, Mark W

    2014-05-01

    Squid are the largest jet propellers in nature as adults, but as paralarvae they are some of the smallest, faced with the inherent inefficiency of jet propulsion at a low Reynolds number. In this study we describe the behavior and kinematics of locomotion in 1 mm paralarvae of Dosidicus gigas, the smallest squid yet studied. They swim with hop-and-sink behavior and can engage in fast jets by reducing the size of the mantle aperture during the contraction phase of a jetting cycle. We go on to explore the general effects of a variable mantle and funnel aperture in a theoretical model of jet propulsion scaled from the smallest (1 mm mantle length) to the largest (3 m) squid. Aperture reduction during mantle contraction increases propulsive efficiency at all squid sizes, although 1 mm squid still suffer from low efficiency (20%) because of a limited speed of contraction. Efficiency increases to a peak of 40% for 1 cm squid, then slowly declines. Squid larger than 6 cm must either reduce contraction speed or increase aperture size to maintain stress within maximal muscle tolerance. Ecological pressure to maintain maximum velocity may lead them to increase aperture size, which reduces efficiency. This effect might be ameliorated by nonaxial flow during the refill phase of the cycle. Our model's predictions highlight areas for future empirical work, and emphasize the existence of complex behavioral options for maximizing efficiency at both very small and large sizes. PMID:24501132

  11. Solar energy apparatus with apertured shield

    Science.gov (United States)

    Collings, Roger J. (Inventor); Bannon, David G. (Inventor)

    1989-01-01

    A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

  12. Soft, Embodied, Situated & Connected

    DEFF Research Database (Denmark)

    Tomico, Oscar; Wilde, Danielle

    2015-01-01

    Soft wearables include clothing and textile-based accessories that incorporate smart textiles and soft electronic interfaces to enable responsive and interactive experiences. When designed well, they leverage the cultural, sociological and material qualities of textiles, fashion and dress; divers...

  13. On Soft Connectedness

    CERN Document Server

    Peyghan, E; Tayebi, A

    2012-01-01

    The soft topological spaces and some their related concepts have stud- ied in [7]. In this paper, we introduce and study the notions of soft connected topological spaces after a review of preliminary definitions.

  14. A Method for Synthetic Aperture Compounding

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2010-01-01

    An approach to perform ultrasound spatial compounding using synthetic aperture data is proposed. The approach allows compounding to be performed for any number of directions without reducing the frame rate or temporal resolution. It is demonstrated how the contrast is improved by compounding and...... obtained when using 5 images. Using the same RF data, a synthetic aperture image without compounding reveals a CNR of -0.36, -0.93, -1.23, and -1.61 dB for the four cysts, respectively....

  15. Large aperture calorimeter for fusion laser measurements

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, J.G.; Smith, P.A.

    The authors designed and constructed a large aperture calorimeter intended for laser fusion measurements on beams up to 20 cm diameter. The laser beam is absorbed in a glass disc backed by a disc carry a resistance wire. Although it performs essentially as expected with a noise equivalent energy of 20 mJ and a maximum energy of about 100 J, difficulties in construction give a 17% variation of sensitivity across the aperture. To overcome this problem it would probably be necessary to adopt an integral construction with the resistance bridge formed from an etched film on the back of the absorbing glass.

  16. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin

    2013-01-01

    Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

  17. Synthetic aperture radar capabilities in development

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  18. IMPROVED SYNTHETIC APERTURE SONAR MOTION COMPENSATION COMBINED DPCA WITH SUB-APERTURE IMAGE CORRELATION

    Institute of Scientific and Technical Information of China (English)

    Liu Wei; Zhang Chunhua; Liu Jiyuan

    2009-01-01

    Estimation precision of Displaced Phase Center Algorithm (DPCA) is affected by the number of displaced phase center pairs, the bandwidth of transmitting signal and many other factors. Detailed analysis is made on DPCA's estimation precision. Analysis results show that the directional vector estimation precision of DPCA is low, which will produce accumulating errors when phase centers' track is estimated. Because of this reason, DPCA suffers from accumulating errors seriously. To overcome this problem, a method combining DPCA with Sub Aperture Image Correlation (SAIC) is presented. Large synthetic aperture is divided into sub-apertures. Micro errors in sub-aperture are estimated by DPCA and compensated to raw echo data. Bulk errors between sub-apertures are estimated by SAIC and compensated directly to sub-aperture images. After that, sub-aperture images are directly used to generate ultimate SAS image. The method is applied to the lake-trial dataset of a 20 kHz SAS prototype system. Results show the method can successfully remove the accumulating error and produce a better SAS image.

  19. Analytic inversion in synthetic aperture radar.

    OpenAIRE

    Rothaus, O. S.

    1994-01-01

    A method of processing synthetic aperture radar signals that avoids some of the approximations currently in use that appear to be responsible for severe phase distortions is described. As a practical matter, this method requires N3 numerical operations, as opposed to the N2 ln N currently the case, but N3 is now easily managed, for N in the range of interest.

  20. Experiences on synthetic aperture focussing technique (SAFT)

    International Nuclear Information System (INIS)

    Imaging based on the synthetic aperture focussing technique (SAFT) improves the reliability of sizing and characterisation of structural discontinuities found in non-destructive testing of nuclear components. One of the main advantages of this technique is an improvement of signal-to-noise-ratio. The advantages are discussed in terms of practical applications and theory. (orig.)

  1. Compound imaging using Synthetic Aperture Sequential Beamformation

    DEFF Research Database (Denmark)

    Jensen, Casper Bo; Jensen, Jonas; Hemmsen, Martin Christian;

    2011-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is a technique with low complexity and the ability to yield a more uniform lateral resolution with range. However, the presence of speckle artifacts in ultrasound images degrades the contrast. In conventional imaging speckle is reduced by using...

  2. Interferometric Synthetic Aperture Microwave Radiometers : an Overview

    Science.gov (United States)

    Colliander, Andreas; McKague, Darren

    2011-01-01

    This paper describes 1) the progress of the work of the IEEE Geoscience and Remote Sensing Society (GRSS) Instrumentation and Future Technologies Technical Committee (IFT-TC) Microwave Radiometer Working Group and 2) an overview of the development of interferometric synthetic aperture microwave radiometers as an introduction to a dedicated session.

  3. Parametric Beamformer for Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt

    2006-01-01

    In this paper a parametric beamformer, which can handle all imaging modalities including synthetic aperture imaging, is presented. The image lines and apodization coefficients are specified parametrically, and the lines can have arbitrary orientation and starting point in 3D coordinates. The beam...

  4. Parametric Transverse Patterns in Broad Aperture Lasers

    DEFF Research Database (Denmark)

    Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik

    1998-01-01

    Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence on the...... geometrical size of the system is demonstrated even in the case of large-scale systems....

  5. A modular approach toward extremely large apertures

    Science.gov (United States)

    Woods, A. A., Jr.

    1981-02-01

    Modular antenna construction can provide a significant increase in reflector aperture size over deployable reflectors. The modular approach allows reflective mesh surfaces to be supported by a minimum of structure. The kinematics of the selected deployable design approach were validated by the subscale demonstration model. Further design refinements on the module structural/joints and design optimization on intermodule joints are needed.

  6. Optimization of Synthetic Aperture Image Quality

    DEFF Research Database (Denmark)

    Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando;

    2016-01-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameter...

  7. Vowel Aperture and Syllable Segmentation in French

    Science.gov (United States)

    Goslin, Jeremy; Frauenfelder, Ulrich H.

    2008-01-01

    The theories of Pulgram (1970) suggest that if the vowel of a French syllable is open then it will induce syllable segmentation responses that result in the syllable being closed, and vice versa. After the empirical verification that our target French-speaking population was capable of distinguishing between mid-vowel aperture, we examined the…

  8. Dynamic metamaterial aperture for microwave imaging

    Science.gov (United States)

    Sleasman, Timothy; F. Imani, Mohammadreza; Gollub, Jonah N.; Smith, David R.

    2015-11-01

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  9. Perceiving Affordances for Fitting through Apertures

    Science.gov (United States)

    Ishak, Shaziela; Adolph, Karen E.; Lin, Grace C.

    2008-01-01

    Affordances--possibilities for action--are constrained by the match between actors and their environments. For motor decisions to be adaptive, affordances must be detected accurately. Three experiments examined the correspondence between motor decisions and affordances as participants reached through apertures of varying size. A psychophysical…

  10. Optimization of Spatiotemporal Apertures in Channel Sounding

    DEFF Research Database (Denmark)

    Pedersen, Troels; Pedersen, Claus; Yin, Xuefeng;

    2008-01-01

    In this paper we investigate the impact of the spatio-temporal aperture of a channel sounding system equipped with antenna arrays at the transmitter and receiver on the accuracy of joint estimation of Doppler frequency and bi-direction. The contribution of this work is three-fold. Firstly, we sta...

  11. Interdisciplinary science with large aperture detectors

    Directory of Open Access Journals (Sweden)

    Wiencke Lawrence

    2013-06-01

    Full Text Available Large aperture detector systems to measure high energy cosmic rays also offer unique opportunities in other areas of science. Disciplines include geophysics such as seismic and volcanic activity, and atmospheric science ranging from clouds to lightning to aerosols to optical transients. This paper will discuss potential opportunities based on the ongoing experience of the Pierre Auger Observatory.

  12. Parametric Transverse Patterns in Broad Aperture Lasers

    DEFF Research Database (Denmark)

    Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik

    1998-01-01

    Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...... on the geometrical size of the system is demonstrated even in the case of large-scale systems....

  13. Dynamic metamaterial aperture for microwave imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)

    2015-11-16

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  14. Sonar path correction in synthetic aperture processing

    NARCIS (Netherlands)

    Groen, J.; Hansen, R.E.; Sabel, J.C.

    2003-01-01

    In the next generation of mine hunting sonars, in particular on Autonomous Underwater Vehicles (AUVs), Synthetic Aperture Sonar (SAS) will play an important role. The benefit of SAS is to increase resolution and signal-tonoise ratio by coherent processing of successive pings. A challenge in SAS is t

  15. Diffraction contrast imaging using virtual apertures

    Energy Technology Data Exchange (ETDEWEB)

    Gammer, Christoph, E-mail: cgammer@lbl.gov [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Department of Materials Science and Engineering, University of California, Berkeley (United States); Physics of Nanostructured Materials, Faculty of Physics, University of Vienna (Austria); Burak Ozdol, V. [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Liebscher, Christian H.; Minor, Andrew M. [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Department of Materials Science and Engineering, University of California, Berkeley (United States)

    2015-08-15

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field.

  16. From Playroom to Lab: Tough Stretchable Electronics Analyzed with a Tabletop Tensile Tester Made from Toy‐Bricks

    Science.gov (United States)

    Kettlgruber, Gerald; Siket, Christian M.; Drack, Michael; Graz, Ingrid M.; Cakmak, Umut; Major, Zoltan; Kaltenbrunner, Martin; Bauer, Siegfried

    2016-01-01

    Toy bricks are an ideal platform for the cost‐effective rapid prototyping of a tabletop tensile tester with measurement accuracy on par with expensive, commercially available laboratory equipment. Here, a tester is presented that is not only a versatile demonstration device in mechanics, electronics, and physics education and an eye‐catcher on exhibitions, but also a powerful tool for stretchable electronics research. Following the “open‐source movement” the build‐up of the tester is described and all the details for easy reproduction are disclosed. A a new design of highly conformable all‐elastomer based graded rigid island printed circuit boards is developed. Tough bonded to this elastomer substrate are imperceptible electronic foils bearing conductors and off‐the‐shelf microelectronics, paving the way for next generation smart electronic appliances. PMID:27588259

  17. 53 W average power few-cycle fiber laser system generating soft x rays up to the water window.

    Science.gov (United States)

    Rothhardt, Jan; Hädrich, Steffen; Klenke, Arno; Demmler, Stefan; Hoffmann, Armin; Gotschall, Thomas; Eidam, Tino; Krebs, Manuel; Limpert, Jens; Tünnermann, Andreas

    2014-09-01

    We report on a few-cycle laser system delivering sub-8-fs pulses with 353 μJ pulse energy and 25 GW of peak power at up to 150 kHz repetition rate. The corresponding average output power is as high as 53 W, which represents the highest average power obtained from any few-cycle laser architecture so far. The combination of both high average and high peak power provides unique opportunities for applications. We demonstrate high harmonic generation up to the water window and record-high photon flux in the soft x-ray spectral region. This tabletop source of high-photon flux soft x rays will, for example, enable coherent diffractive imaging with sub-10-nm resolution in the near future.

  18. Cavity-excited Huygens' metasurface antennas: near-unity aperture efficiency from arbitrarily-large apertures

    CERN Document Server

    Epstein, Ariel; Eleftheriades, George V

    2015-01-01

    One of the long-standing problems in antenna engineering is the realization of highly-directive beams using low-profile devices. In this paper we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source cavity excitation is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectrum typical to standard partially-reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern. As shown, a single semianalytical formalism can be followed to achieve control of a variety of radiation features, such as the d...

  19. Soft measures - soft options or smart choice?

    OpenAIRE

    Anable, J.; Kirkbride, A.; Sloman, L.; Newson, C; Cairns, S.; Goodwin, P

    2005-01-01

    In recent years, there has been growing interest in a range of transport policy initiatives which are now widely described as ‘soft measures’. Soft measures usually seek to give better information and opportunities which affect the free choices made by individuals, mostly by facilitating attractive, relatively uncontroversial, and relatively cheap alternatives. They include initiatives such as school and workplace travel plans, personalised journey planning, car clubs, public tran...

  20. Multi-static synthetic aperture radar and inverse scattering

    OpenAIRE

    Gustafsson, Mats

    2004-01-01

    In this paper synthetic aperture radar is analyzed from an inverse scattering perspective. It is shown that the classical point scattering model can be generalized to a dipole scattering model. The dipole scattering model reduces to the point scattering model for small aperture angles. For large aperture angles or multiple illumination apertures the dipole model gives an anisotropic reflectivity such that orthogonal scattering processes are separated. Moreover, it is shown th...

  1. Antenna-Aperture Synthesis for Hyperband SAR Antennas

    Science.gov (United States)

    Baum, C. E.

    This paper introduces an aperture synthesis procedure for producing a desired pulse shape, including the desired frequency spectrum of the pulse. This is accomplished by controlling the time-of-arrival of fields on the aperture plane, thereby synthesizing a delay as a function of radius for the arrival of a stop-function TEM-like wave on the aperture plane.

  2. High Gain, Very Low Areal Density, Scalable RF Apertures Enabled by Membrane Aperture Shell Technology (MAST) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose that the Membrane Aperture Shell Technology (MAST) approach be expanded with a specific focus on space exploration orbiting comm network RF aperture...

  3. Soft-rot” in a wood sample of Dicranostyles: a rectification

    NARCIS (Netherlands)

    Mennega, Alberta M.W.; Jutte, Suzanne M.

    1972-01-01

    Peculiar slit-like apertures in the walls of the fibre tracheids of Dicranostyles mildbraediana described in a previous paper, were recognized by the co-author as the result of a ‘soft-rot’ fungal attack. Consequently these structures are not a characteristic feature of this species.

  4. Performance limits for Synthetic Aperture Radar.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2006-02-01

    The performance of a Synthetic Aperture Radar (SAR) system depends on a variety of factors, many which are interdependent in some manner. It is often difficult to ''get your arms around'' the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics, no matter how bright the engineer tasked to generate a system design. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall SAR system. For example, there are definite optimum frequency bands that depend on weather conditions and range, and minimum radar PRF for a fixed real antenna aperture dimension is independent of frequency. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the ''seek time''.

  5. Flame Reconstruction Using Synthetic Aperture Imaging

    CERN Document Server

    Murray, Preston; Tree, Dale; Truscott, Tadd

    2011-01-01

    Flames can be formed by burning methane (CH4). When oxygen is scarce, carbon particles nucleate into solid particles called soot. These particles emit photons, making the flame yellow. Later, methane is pre-mixed with air forming a blue flame; burning more efficiently, providing less soot and light. Imaging flames and knowing their temperature are vital to maximizing efficiency and validating numerical models. Most temperature probes disrupt the flame and create differences leading to an inaccurate measurement of the flame temperature. We seek to image the flame in three dimensions using synthetic aperture imaging. This technique has already successfully measured velocity fields of a vortex ring [1]. Synthetic aperture imaging is a technique that views one scene from multiple cameras set at different angles, allowing some cameras to view objects that are obscured by others. As the resulting images are overlapped different depths of the scene come into and out of focus, known as focal planes, similar to tomogr...

  6. IR aperture measurement at β*=40 cm

    CERN Document Server

    Bruce, Roderik; Hermes, Pascal Dominik; Kwee-Hinzmann, Regina; Mereghetti, Alessio; Mirarchi, Daniele; Redaelli, Stefano; Salvachua Ferrando, Belen Maria; Skowronski, Piotr Krzysztof; Valentino, Gianluca; Valloni, Alessandra; CERN. Geneva. ATS Department

    2015-01-01

    This note summarizes MD 307, performed on August 27 2015, during which we measured with beam the global apertures at 6.5 TeV with IR1 and IR5 squeezed to β* =40 cm and a half crossing angle of 205 rad. The measurement technique involved opening collimators in steps, while inducing beam losses at each step, until the main loss location moved from the collimators to the global bottleneck in one of the triplets. Measurements were performed in both beams and planes, and each measurement gave the minimum triplet aperture over IR1 and IR5. The results are in very good agreement with theoretical predictions. At the end of the MD, an asynchronous beam dump test was performed with all collimators moved in to so-called 2-σ retraction settings. This MD is one in a series meant to address various open points for the reach in β* in Run II.

  7. Synthetic aperture tissue and flow ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav

    at every emission, which makes it possible to average over a large number of lines. This makes stationary echo canceling easier and significantly improves the velocity estimates. Only 8 emissions per plane are necessary to create the color flow map. Scanning 12 cm in depth, up to 800 planes can be obtained...... imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture...

  8. On Soft Dual Space of Soft Normed Spaces

    OpenAIRE

    Yazar, Murat Ibrahim; Altun, Yilmaz; Bilgin, Tunay

    2015-01-01

    The concept of Soft set theory was introduced by Molodtsov in the study [8]. Soft real numbers and properties were introduced inthe study [6] and soft normed space was defined in [11]. In this study, firstly we obtain a soft normed space by defining a soft norm on (Real numbers) which is called soft normed real space. By using this normed space we define the soft linear functional and investigate some of its properties. Secondly, we introduce soft dual space and soft dual operator and investi...

  9. Pediatric Soft Tissue Sarcomas

    OpenAIRE

    Loeb, David M.; Thornton, Katherine; Shokek, Ori

    2008-01-01

    Soft tissue sarcomas in children are relatively rare. Approximately 850 to 900 children and adolescents are diagnosed each year with rhabdomyosarcoma (RMS) or one of the non-RMS soft tissue sarcomas (NRSTS). Of these, 350 are cases of RMS. RMS is the most common soft tissue sarcoma in children 14 years old and younger, and NRSTS is more common in adolescents and young adults. Infants also get NRSTS, but their tumors constitute a distinctive set of histologies, including infantile fibrosarcoma...

  10. Phase contrast enhanced high resolution X-ray imaging and tomography of soft tissue

    International Nuclear Information System (INIS)

    A tabletop system for digital high resolution and high sensitivity X-ray micro-radiography has been developed for small-animal and soft-tissue imaging. The system is based on a micro-focus X-ray tube and the semiconductor hybrid position sensitive Medipix2 pixel detector. Transmission radiography imaging, conventionally based only on absorption, is enhanced by exploiting phase-shift effects induced in the X-ray beam traversing the sample. Phase contrast imaging is realized by object edge enhancement. DAQ is done by a novel fully integrated USB-based readout with online image generation. Improved signal reconstruction techniques make use of advanced statistical data analysis, enhanced beam hardening correction and direct thickness calibration of individual pixels. 2D and 3D micro-tomography images of several biological samples demonstrate the applicability of the system for biological and medical purposes including in-vivo and time dependent physiological studies in the life sciences

  11. Development of multilayer Laue Lenses for soft X-ray radiation

    Energy Technology Data Exchange (ETDEWEB)

    Liese, Tobias; Krebs, Hans-Ulrich [Institut fuer Materialphysik, Universitaet Goettingen (Germany); Reese, Michael; Grossmann, Peter; Mann, Klaus [Laser-Laboratorium Goettingen e.V. (Germany)

    2010-07-01

    Despite the improvements of fabrication techniques for Fresnel zone plates as diffractive optics for X-ray microscopy, the spatial resolution with high diffraction efficiencies has reached a limit mostly. A novel approach to focusing soft X-rays in the water window regime (2.3-4.4 nm) is to prepare non-periodic multilayer structures using as 1-dimensional zone plates in Laue diffraction geometry. For this purpose ZrO{sub 2}/Ti multilayers were deposited by pulsed laser deposition (PLD) on Si(111) substrates in ultrahigh vacuum. The interfaces within the multilayer are positioned according to the Fresnel zone plate law. In this contribution, results of the Laue Lens fabrication by focused ion beam (FIB) and lens characteristics measured by a table-top X-ray source are presented.

  12. Feasibility of Swept Synthetic Aperture Ultrasound Imaging.

    Science.gov (United States)

    Bottenus, Nick; Long, Will; Zhang, Haichong K; Jakovljevic, Marko; Bradway, David P; Boctor, Emad M; Trahey, Gregg E

    2016-07-01

    Ultrasound image quality is often inherently limited by the physical dimensions of the imaging transducer. We hypothesize that, by collecting synthetic aperture data sets over a range of aperture positions while precisely tracking the position and orientation of the transducer, we can synthesize large effective apertures to produce images with improved resolution and target detectability. We analyze the two largest limiting factors for coherent signal summation: aberration and mechanical uncertainty. Using an excised canine abdominal wall as a model phase screen, we experimentally observed an effective arrival time error ranging from 18.3 ns to 58 ns (root-mean-square error) across the swept positions. Through this clutter-generating tissue, we observed a 72.9% improvement in resolution with only a 3.75 dB increase in side lobe amplitude compared to the control case. We present a simulation model to study the effect of calibration and mechanical jitter errors on the synthesized point spread function. The relative effects of these errors in each imaging dimension are explored, showing the importance of orientation relative to the point spread function. We present a prototype device for performing swept synthetic aperture imaging using a conventional 1-D array transducer and ultrasound research scanner. Point target reconstruction error for a 44.2 degree sweep shows a reconstruction precision of 82.8 μm and 17.8 μm in the lateral and axial dimensions respectively, within the acceptable performance bounds of the simulation model. Improvements in resolution, contrast and contrast-to-noise ratio are demonstrated in vivo and in a fetal phantom. PMID:26863653

  13. Optimization of Synthetic Aperture Image Quality

    OpenAIRE

    Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Hemmsen, Martin Christian; Jensen, Jørgen Arendt

    2016-01-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameters effecting the image quality of SA is of great importance, and this paper proposes an advanced procedure for optimizing the parameters essential for acquiring an optimal image quality, while generati...

  14. Motion compensation of Synthetic Aperture Radar

    OpenAIRE

    Duncan, David; Long, David

    2003-01-01

    Synthetic aperture radar (SAR) is a digital signal processing technique which enhances the azimuth resolution of a radar image using the target doppler history created by the motion of the radar platform. If the platform deviates from a constant velocity, straight-line path then image quality is lost and image details become unfocused. Motion compensation (MOCO) is a technique in which the position and attitude of the platform is recorded or estimated and then used to correct the scene's dopp...

  15. Simultaneous Navigation and Synthetic Aperture Radar Focusing

    OpenAIRE

    Sjanic, Zoran; Gustafsson, Fredrik

    2015-01-01

    Synthetic aperture radar (SAR) equipment is a radar imaging system that can be used to create high-resolution images of a scene by utilizing the movement of a flying platform. Knowledge of the platforms trajectory is essential to get good and focused images. An emerging application field is real-time SAR imaging using small and cheap platforms where estimation errors in navigation systems imply unfocused images. This contribution investigates a joint estimation of the trajectory and SAR image...

  16. Soft matter physics

    CERN Document Server

    Doi, Masao

    2013-01-01

    Soft matter (polymers, colloids, surfactants and liquid crystals) are an important class of materials in modern technology. They also form the basis of many future technologies, for example in medical and environmental applications. Soft matter shows complex behaviour between fluids and solids, and used to be a synonym of complex materials. Due to the developments of the past two decades, soft condensed matter can now be discussed on the same sound physical basis as solid condensedmatter. The purpose of this book is to provide an overview of soft matter for undergraduate and graduate students

  17. Outdoor synthetic aperture acoustic ground target measurements

    Science.gov (United States)

    Bishop, Steven; Ngaya, Therese-Ann; Vignola, Joe; Judge, John; Marble, Jay; Gugino, Peter; Soumekh, Mehrdad; Rosen, Erik

    2010-04-01

    A novel outdoor synthetic aperture acoustic (SAA) system consists of a microphone and loudspeaker traveling along a 6.3-meter rail system. This is an extension from a prior indoor laboratory measurement system in which selected targets were insonified while suspended in air. Here, the loudspeaker and microphone are aimed perpendicular to their direction of travel along the rail. The area next to the rail is insonified and the microphone records the reflected acoustic signal, while the travel of the transceiver along the rail creates a synthetic aperture allowing imaging of the scene. Ground surfaces consisted of weathered asphalt and short grass. Several surface-laid objects were arranged on the ground for SAA imaging. These included rocks, concrete masonry blocks, grout covered foam blocks; foliage obscured objects and several spherical canonical targets such as a bowling ball, and plastic and metal spheres. The measured data are processed and ground targets are further analyzed for characteristics and features amenable for discrimination. This paper includes a description of the measurement system, target descriptions, synthetic aperture processing approach and preliminary findings with respect to ground surface and target characteristics.

  18. Biomineral repair of abalone shell apertures.

    Science.gov (United States)

    Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

    2013-08-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair.

  19. Coded-aperture imaging in nuclear medicine

    Science.gov (United States)

    Smith, Warren E.; Barrett, Harrison H.; Aarsvold, John N.

    1989-01-01

    Coded-aperture imaging is a technique for imaging sources that emit high-energy radiation. This type of imaging involves shadow casting and not reflection or refraction. High-energy sources exist in x ray and gamma-ray astronomy, nuclear reactor fuel-rod imaging, and nuclear medicine. Of these three areas nuclear medicine is perhaps the most challenging because of the limited amount of radiation available and because a three-dimensional source distribution is to be determined. In nuclear medicine a radioactive pharmaceutical is administered to a patient. The pharmaceutical is designed to be taken up by a particular organ of interest, and its distribution provides clinical information about the function of the organ, or the presence of lesions within the organ. This distribution is determined from spatial measurements of the radiation emitted by the radiopharmaceutical. The principles of imaging radiopharmaceutical distributions with coded apertures are reviewed. Included is a discussion of linear shift-variant projection operators and the associated inverse problem. A system developed at the University of Arizona in Tucson consisting of small modular gamma-ray cameras fitted with coded apertures is described.

  20. Calibration of the TUD Ku-band Synthetic Aperture Radiometer

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1995-01-01

    The TUD Synthetic Aperture Radiometer is a 2-channel demonstration model that can simulate a thinned aperture radiometer having an unfilled aperture consisting of several small antenna elements. Aperture synthesis obtained by interferometric measurements using the antenna elements in pairs......, followed by an image reconstruction based on an inverse Fourier transform, results in an imaging instrument without the need of mechanical scan. The thinned aperture and the non-scanning feature make the technique attractive for low frequency spaceborne radiometer systems, e.g. at L-band. Initial...

  1. Jacobi-Bessel Analysis Of Antennas With Elliptical Apertures.

    Science.gov (United States)

    Rahmat-Samii, Y.

    1989-01-01

    Coordinate transformation improves convergence pattern analysis of elliptical-aperture antennas. Modified version of Jacobi-Bessel expansion for vector diffraction analysis of reflector antennas uses coordinate transformation to improve convergence with elliptical apertures. Expansion converges rapidly for antennas with circular apertures, but less rapidly for elliptical apertures. Difference in convergence behavior between circular and elliptical Jacobi-Bessel algorithms indicated by highest values of indices m, n, and p required to achieve same accuracy in computed radiation pattern of offset paraboloidal antenna with elliptical aperture.

  2. Lessons learned from the first U.S./Russian Federation joint tabletop exercise to prepare for conducting on-site inspections under the Comprehensive Nuclear Test Ban Treaty

    Energy Technology Data Exchange (ETDEWEB)

    Filarowski, C; Gough, R; Hawkins, W; Knowles, S; Kreek, S; MacLeod, G; Rockett, P; Smith, A; Sweeney, J; Wild, J; Wohletz, K

    1999-03-24

    A U.S./Russian Federation Joint Tabletop Exercise took place in Snezhinsk, Russia, from 19 to 24 October 1998, whose objectives were the following: (1) To simulate the actions of the Inspection Team (IT), including interactions with the inspected State Party (ISP), in order to examine different ways the United States and Russian Federation (RF) approach inspections and develop appropriate recommendations for the international community. (2) To identify ambiguities and contradictions in the interpretation of Treaty and Protocol provisions that might become apparent in the course of an inspection and that need clarification in connection with the development of Operational Manuals and on-site inspection (OSI) infrastructure. (3) To confirm the efficacy of using bilateral tabletop exercises to assist in developing an effective Comprehensive Test Ban Treaty (CTBT) verification regime. (4) To identify strong and weak points in the preparation and implementation methods of such exercises for the purpose of further improving possible future exercises.

  3. Two-Dimensional Synthetic-Aperture Radiometer

    Science.gov (United States)

    LeVine, David M.

    2010-01-01

    A two-dimensional synthetic-aperture radiometer, now undergoing development, serves as a test bed for demonstrating the potential of aperture synthesis for remote sensing of the Earth, particularly for measuring spatial distributions of soil moisture and ocean-surface salinity. The goal is to use the technology for remote sensing aboard a spacecraft in orbit, but the basic principles of design and operation are applicable to remote sensing from aboard an aircraft, and the prototype of the system under development is designed for operation aboard an aircraft. In aperture synthesis, one utilizes several small antennas in combination with a signal processing in order to obtain resolution that otherwise would require the use of an antenna with a larger aperture (and, hence, potentially more difficult to deploy in space). The principle upon which this system is based is similar to that of Earth-rotation aperture synthesis employed in radio astronomy. In this technology the coherent products (correlations) of signals from pairs of antennas are obtained at different antenna-pair spacings (baselines). The correlation for each baseline yields a sample point in a Fourier transform of the brightness-temperature map of the scene. An image of the scene itself is then reconstructed by inverting the sampled transform. The predecessor of the present two-dimensional synthetic-aperture radiometer is a one-dimensional one, named the Electrically Scanned Thinned Array Radiometer (ESTAR). Operating in the L band, the ESTAR employs aperture synthesis in the cross-track dimension only, while using a conventional antenna for resolution in the along-track dimension. The two-dimensional instrument also operates in the L band to be precise, at a frequency of 1.413 GHz in the frequency band restricted for passive use (no transmission) only. The L band was chosen because (1) the L band represents the long-wavelength end of the remote- sensing spectrum, where the problem of achieving adequate

  4. Fast-neutron, coded-aperture imager

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F., E-mail: bernard.phlips@nrl.navy.mil; Hutcheson, Anthony L., E-mail: anthony.hutcheson@nrl.navy.mil; Wulf, Eric A., E-mail: eric.wulf@nrl.navy.mil

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  5. Embodying Soft Wearables Research

    DEFF Research Database (Denmark)

    Tomico, Oscar; Wilde, Danielle

    2016-01-01

    of soft wearables. Throughout, we will experiment with how embodied design research techniques might be shared, developed, and used as direct and unmediated vehicles for their own reporting. Rather than engage in oral presentations, participants will lead each other through a proven embodied method...... and knowledge transfer in the context of soft wearables....

  6. Robotics: Generation soft

    Science.gov (United States)

    Mazzolai, Barbara; Mattoli, Virgilio

    2016-08-01

    Meet the octobot, the first robot to be made entirely from soft materials. Powered by a chemical reaction and controlled by a fluidic logic circuit, it heralds a generation of soft robots that might surpass conventional machines. See Letter p.451

  7. learning and soft skills

    DEFF Research Database (Denmark)

    Rasmussen, Lauge Baungaard

    2000-01-01

    Learning of soft skills are becoming more and more necessary due to the complexe development of modern companies and their environments. However, there seems to be a 'gap' between intentions and reality regarding need of soft skills and the possiblities to be educated in this subject in particular...

  8. Evaluating six soft approaches

    Directory of Open Access Journals (Sweden)

    Lene Sørensen

    2008-09-01

    Full Text Available The paper introduces and evaluates six soft approaches used in strategy development and planning. We take a planner’s perspective on discussing the concepts of strategy development and planning. This means that we see strategy development and planning as learning processes based on Ackoff’s interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable for supporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using such a conceptual framework for evaluations of soft approaches increases the understanding of them, their transparency, and their usability in practice.

  9. Soft Pion Processes

    Science.gov (United States)

    Nambu, Y.

    1968-01-01

    My talk is concerned with a review, not necessarily of the latest theoretical developments, but rather of an old idea which has contributed to recent theoretical activities. By soft pion processes I mean processes in which low energy pions are emitted or absorbed or scattered, just as we use the word soft photon in a similar context. Speaking more quantitatively, we may call a pion soft if its energy is small compared to a natural scale in the reaction. This scale is determined by the particular dynamics of pion interaction, and one may roughly say that a pion is soft if its energy is small compared to the energies of the other individual particles that participate in the reaction. It is important to note at this point that pion is by far the lightest member of all the hadrons, and much of the success of the soft pion formulas depends on this fact.

  10. Lasers, extreme UV and soft X-ray

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, Joseph [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-20

    Three decades ago, large ICF lasers that occupied entire buildings were used as the energy sources to drive the first X-ray lasers. Today X-ray lasers are tabletop, spatially coherent, high-repetition rate lasers that enable many of the standard optical techniques such as interferometry to be extended to the soft X-ray regime between wavelengths of 10 and 50 nm. Over the last decade X-ray laser performance has been improved by the use of the grazing incidence geometry, diode-pumped solid-state lasers, and seeding techniques. The dominant X-ray laser schemes are the monopole collisional excitation lasers either driven by chirped pulse amplification (CPA) laser systems or capillary discharge. The CPA systems drive lasing in neon-like or nickel-like ions, typically in the 10 – 30 nm range, while the capillary system works best for neon-like argon at 46.9 nm. Most researchers use nickel-like ion lasers near 14 nm because they are well matched to the Mo:Si multilayer mirrors that have peak reflectivity near 13 nm and are used in many applications. As a result, the last decade has seen the birth of the X-ray free electron laser (XFEL) that can reach wavelengths down to 0.15 nm and the inner-shell Ne laser at 1.46 nm.

  11. Optimization of synthetic aperture image quality

    Science.gov (United States)

    Moshavegh, Ramin; Jensen, Jonas; Villagomez-Hoyos, Carlos A.; Stuart, Matthias B.; Hemmsen, Martin Christian; Jensen, Jørgen Arendt

    2016-04-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameters effecting the image quality of SA is of great importance, and this paper proposes an advanced procedure for optimizing the parameters essential for acquiring an optimal image quality, while generating high resolution SA images. Optimization of the image quality is mainly performed based on measures such as F-number, number of emissions and the aperture size. They are considered to be the most contributing acquisition factors in the quality of the high resolution images in SA. Therefore, the performance of image quality is quantified in terms of full-width at half maximum (FWHM) and the cystic resolution (CTR). The results of the study showed that SA imaging with only 32 emissions and maximum sweep angle of 22 degrees yields a very good image quality compared with using 256 emissions and the full aperture size. Therefore the number of emissions and the maximum sweep angle in the SA can be optimized to reach a reasonably good performance, and to increase the frame rate by lowering the required number of emissions. All the measurements are performed using the experimental SARUS scanner connected to a λ/2-pitch transducer. A wire phantom and a tissue mimicking phantom containing anechoic cysts are scanned using the optimized parameters for the transducer. Measurements coincide with simulations.

  12. The Configurable Aperture Space Telescope (CAST)

    Science.gov (United States)

    Ennico, Kimberly; Bendek, Eduardo A.; Lynch, Dana H.; Vassigh, Kenny K.; Young, Zion

    2016-07-01

    The Configurable Aperture Space Telescope, CAST, is a concept that provides access to a UV/visible-infrared wavelength sub-arcsecond imaging platform from space, something that will be in high demand after the retirement of the astronomy workhorse, the 2.4 meter diameter Hubble Space Telescope. CAST allows building large aperture telescopes based on small, compatible and low-cost segments mounted on autonomous cube-sized satellites. The concept merges existing technology (segmented telescope architecture) with emerging technology (smartly interconnected modular spacecraft, active optics, deployable structures). Requiring identical mirror segments, CAST's optical design is a spherical primary and secondary mirror telescope with modular multi-mirror correctors placed at the system focal plane. The design enables wide fields of view, up to as much as three degrees, while maintaining aperture growth and image performance requirements. We present a point design for the CAST concept based on a 0.6 meter diameter (3 x 3 segments) growing to a 2.6 meter diameter (13 x 13 segments) primary, with a fixed Rp=13,000 and Rs=8,750 mm curvature, f/22.4 and f/5.6, respectively. Its diffraction limited design uses a two arcminute field of view corrector with a 7.4 arcsec/mm platescale, and can support a range of platescales as fine as 0.01 arcsec/mm. Our paper summarizes CAST, presents a strawman optical design and requirements for the underlying modular spacecraft, highlights design flexibilities, and illustrates applications enabled by this new method in building space observatories.

  13. Cancellation of singularities for synthetic aperture radar

    International Nuclear Information System (INIS)

    In a basic model for synthetic aperture radar (SAR) imaging, one wishes to recover a function or distribution f from line integrals over circles whose centers lie on a given curve γ. In this paper, we consider the problem of recovering the singularities (wavefront set) of f given its SAR data, and specifically whether it is possible to choose a singular f whose singularities are hidden from γ, meaning that its SAR data is smooth. We show that f 's singularities can be hidden to leading order if a certain discrete reflection map is the identity, and give examples where this is the case. Finally, numerical experiments illustrate the hiding of singularities. (paper)

  14. Multibeam synthetic aperture radar for global oceanography

    Science.gov (United States)

    Jain, A.

    1979-01-01

    A single-frequency multibeam synthetic aperture radar concept for large swath imaging desired for global oceanography is evaluated. Each beam iilluminates a separate range and azimuth interval, and images for different beams may be separated on the basis of the Doppler spectrum of the beams or their spatial azimuth separation in the image plane of the radar processor. The azimuth resolution of the radar system is selected so that the Doppler spectrum of each beam does not interfere with the Doppler foldover due to the finite pulse repetition frequency of the radar system.

  15. Cancellation of singularities for synthetic aperture radar

    Science.gov (United States)

    Caday, Peter

    2015-01-01

    In a basic model for synthetic aperture radar (SAR) imaging, one wishes to recover a function or distribution f from line integrals over circles whose centers lie on a given curve γ. In this paper, we consider the problem of recovering the singularities (wavefront set) of f given its SAR data, and specifically whether it is possible to choose a singular f whose singularities are hidden from γ, meaning that its SAR data is smooth. We show that f 's singularities can be hidden to leading order if a certain discrete reflection map is the identity, and give examples where this is the case. Finally, numerical experiments illustrate the hiding of singularities.

  16. Digital exploitation of synthetic aperture radar

    Science.gov (United States)

    Wagner, H. L.; Shuchman, R. A.

    1977-01-01

    A digital processing and analysis scheme for use with digitized synthetic aperture radar data was developed. Using data from a four channel system, the imagery is preprocessed using specially designed software and then analyzed using preexisting facilities originally intended for use with MSS type data. Geometric and radiometric correction may be performed if desired, as well as classification analysis, Fast Fourier transform, filtering and level slice and display functions. The system provides low cost output in real time, permitting interactive imagery analysis. System information flow diagrams as well as sample output products are shown.

  17. Tissue Harmonic Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Rasmussen, Joachim; Jensen, Jørgen Arendt

    2014-01-01

    Synthetic aperture sequential beamforming (SASB) and tissue har- monic imaging (THI) are combined to improve the image quality of medical ultrasound imaging. The technique is evaluated in a compar- ative study against dynamic receive focusing (DRF). The objective is to investigate if SASB combined...... with THI improves the image qual- ity compared to DRF-THI. The major benet of SASB is a reduced bandwidth between the probe and processing unit. A BK Medical 2202 Ultraview ultrasound scanner was used to acquire beamformed RF data for oine evaluation. The acquisition was made interleaved between methods...

  18. Keyhole reflection-mode coherent diffraction imaging of nano-patterned surfaces using a tabletop EUV source

    Science.gov (United States)

    Shanblatt, Elisabeth; Seaberg, Matthew; Zhang, Bosheng; Gardner, Dennis; Murnane, Margaret; Kapyetn, Henry; Adams, Daniel

    2014-03-01

    We demonstrate the first reflection-mode keyhole coherent diffraction imaging (CDI) of non-isolated samples from a single diffraction pattern. A tabletop high harmonic generation (HHG) beam at 30 nm with a curved wave-front is used to illuminate Ti nano-patterns on a Si substrate at 45 degree angle of incidence. The 30 nm illumination beam profile is first characterized using ptychograhic CDI. Keyhole CDI is then used to image the nano-sample. In contrast to ptychography CDI, keyhole CDI needs only one diffraction pattern, and therefore requires no scanning of the sample. This is a significant advantage for ultrafast pump-probe imaging of thermal or spin transport, allowing a sequence of time-delayed images of the same region to be easily acquired. Our technique opens the door for imaging dynamics in nanostructures with sub-10 nm spatial resolution and fs temporal resolution. National Science Foundation Engineering Research Center in EUV Science and Technology, AMRDEC, DARPA PULSE, SRC grant 2013-OJ-2443, NSSEFF Fellowship, NSF IGERT program.

  19. Efficacy and predictability of soft tissue ablation using a prototype Raman-shifted alexandrite laser

    Science.gov (United States)

    Kozub, John A.; Shen, Jin-H.; Joos, Karen M.; Prasad, Ratna; Shane Hutson, M.

    2015-10-01

    Previous research showed that mid-infrared free-electron lasers could reproducibly ablate soft tissue with little collateral damage. The potential for surgical applications motivated searches for alternative tabletop lasers providing thermally confined pulses in the 6- to-7-μm wavelength range with sufficient pulse energy, stability, and reliability. Here, we evaluate a prototype Raman-shifted alexandrite laser. We measure ablation thresholds, etch rates, and collateral damage in gelatin and cornea as a function of laser wavelength (6.09, 6.27, or 6.43 μm), pulse energy (up to 3 mJ/pulse), and spot diameter (100 to 600 μm). We find modest wavelength dependence for ablation thresholds and collateral damage, with the lowest thresholds and least damage for 6.09 μm. We find a strong spot-size dependence for all metrics. When the beam is tightly focused (˜100-μm diameter), ablation requires more energy, is highly variable and less efficient, and can yield large zones of mechanical damage (for pulse energies >1 mJ). When the beam is softly focused (˜300-μm diameter), ablation proceeded at surgically relevant etch rates, with reasonable reproducibility (5% to 12% within a single sample), and little collateral damage. With improvements in pulse-energy stability, this prototype laser may have significant potential for soft-tissue surgical applications.

  20. Generation and application of the soft X-ray laser beam based on capillary discharge

    International Nuclear Information System (INIS)

    In this work we report on the generation and characterization of a focused soft X-ray laser beam with intensity and energy density that exceed the threshold for the ablation of PMMA. We demonstrate a feasibility of direct ablation of holes using a focused soft X-ray laser beam. Ablated craters in PMMA/gold-covered-PMMA samples were obtained by focusing the soft X-ray Ar8+ laser pulses generated by a 46.9 nm tabletop capillary-discharge-pumped driver with a spherical Si/Sc multilayer mirror. It was found that the focused beam is capable by one shot to ablate PMMA, even if the focus is significantly influenced by astigmatism. Analysis of the laser beam footprints by atomic force microscope shows that ablated holes have periodic surface structure (similarly as Laser-Induced Periodic Surface Structure) with period ∼2,8 μm and with peak-to-peak depth ∼5-10 nm.

  1. Evaluating six soft approaches

    DEFF Research Database (Denmark)

    Sørensen, Lene; Vidal, Rene Victor Valqui

    2006-01-01

    ’s interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable for supporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology......, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using...

  2. Evaluating six soft approaches

    DEFF Research Database (Denmark)

    Sørensen, Lene Tolstrup; Vidal, Rene Victor Valqui

    2008-01-01

    's interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable forsupporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology......, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using...

  3. Evaluating Six Soft Approaches

    DEFF Research Database (Denmark)

    Sørensen, Lene Tolstrup; Valqui Vidal, René Victor

    2008-01-01

    's interactive planning principles to be supported by soft approaches in carrying out the principles in action. These six soft approaches are suitable forsupporting various steps of the strategy development and planning process. These are the SWOT analysis, the Future Workshop, the Scenario methodology......, Strategic Option Development and Analysis, Strategic Choice Approach and Soft Systems Methodology. Evaluations of each methodology are carried out using a conceptual framework in which the organisation, the result, the process and the technology of the specific approach are taken into consideration. Using...

  4. Multi-mission, autonomous, synthetic aperture radar

    Science.gov (United States)

    Walls, Thomas J.; Wilson, Michael L.; Madsen, David; Jensen, Mark; Sullivan, Stephanie; Addario, Michael; Hally, Iain

    2014-05-01

    Unmanned aerial systems (UASs) have become a critical asset in current battlespaces and continue to play an increasing role for intelligence, surveillance and reconnaissance (ISR) missions. With the development of medium-to-low altitude, rapidly deployable aircraft platforms, the ISR community has seen an increasing push to develop ISR sensors and systems with real-time mission support capabilities. This paper describes recent flight demonstrations and test results of the RASAR (Real-time, Autonomous, Synthetic Aperture Radar) sensor system. RASAR is a modular, multi-band (L and X) synthetic aperture radar (SAR) imaging sensor designed for self-contained, autonomous, real-time operation with mission flexibility to support a wide range of ISR needs within the size, weight and power constraints of Group III UASs. The sensor command and control and real-time image formation processing are designed to allow integration of RASAR into a larger, multi-intelligence system of systems. The multi-intelligence architecture and a demonstration of real-time autonomous cross-cueing of a separate optical sensor will be presented.

  5. Sparse aperture mask wavefront sensor testbed results

    Science.gov (United States)

    Subedi, Hari; Zimmerman, Neil T.; Kasdin, N. Jeremy; Riggs, A. J. E.

    2016-07-01

    Coronagraphic exoplanet detection at very high contrast requires the estimation and control of low-order wave- front aberrations. At Princeton High Contrast Imaging Lab (PHCIL), we are working on a new technique that integrates a sparse-aperture mask (SAM) with a shaped pupil coronagraph (SPC) to make precise estimates of these low-order aberrations. We collect the starlight rejected from the coronagraphic image plane and interfere it using a sparse aperture mask (SAM) at the relay pupil to estimate the low-order aberrations. In our previous work we numerically demonstrated the efficacy of the technique, and proposed a method to sense and control these differential aberrations in broadband light. We also presented early testbed results in which the SAM was used to sense pointing errors. In this paper, we will briefly overview the SAM wavefront sensor technique, explain the design of the completed testbed, and report the experimental estimation results of the dominant low-order aberrations such as tip/tit, astigmatism and focus.

  6. Influence of circular aperture on high-order harmonic generation

    Institute of Scientific and Technical Information of China (English)

    Tingting Liu(刘婷婷); Weixin Lu(陆伟新); Dawei Wang(王大威); Hong Yang(杨宏); Qihuang Gong(龚旗煌)

    2003-01-01

    The influence of circular aperture on the intensity of high-order harmonic generation (HHG) with intense femtosecond laser pulse was studied both experimentally and theoretically. The intensity variety of HHG with the diameter of circular aperture was observed in pulsed Ar gas. The result was discussed and interpreted in terms of the theory of Hankel transform. It is found that using the Gaussian beam truncated by an aperture could enhance the conversion efficiency of HHG at certain conditions.

  7. Optical nanolithography with λ/15 resolution using bowtie aperture array

    Science.gov (United States)

    Wen, Xiaolei; Traverso, Luis M.; Srisungsitthisunti, Pornsak; Xu, Xianfan; Moon, Euclid E.

    2014-10-01

    We report optical parallel nanolithography using bowtie apertures with the help of the interferometric-spatial-phase-imaging (ISPI) technique. The ISPI system can detect and control the distance between the bowtie aperture, and photoresist with a resolution of sub-nanometer level. It overcomes the difficulties brought by the light divergence of bowtie apertures. Parallel nanolithography with feature size of 22 ± 5 nm is achieved. This technique combines high resolution, parallel throughput, and low cost, which is promising for practical applications.

  8. Magnetically tunable broadband transmission through a single small aperture

    OpenAIRE

    Ke Bi; Wenjun Liu; Yunsheng Guo; Guoyan Dong; Ming Lei

    2015-01-01

    Extraordinary transmission through a small aperture is of great interest. However, it faces a limitation that most of approaches can not realize the tunable transmission property, which is not benefit for the miniaturization of the microwave system. Here, we demonstrate a magnetically tunable broadband transmission through a small aperture. By placing two ferrite rods symmetrically on both sides of a single small aperture, the strongly localized electromagnetic fields are effectively coupled ...

  9. An Introduction of Aperture Coupled Microstrip Slot Antenna

    OpenAIRE

    Zarreen Aijaz; S.C Shrivastava

    2010-01-01

    A microstrip slot antenna is very small and lightweight still it has the problem of back radiation due to which power loss occurs and the SAR increases. To reduce the back lobe a technique introduces i.e. aperture coupled microstrip slot antenna which reduces the back lobe as well as increases the bandwidth of the antenna. Aperture coupled microstrip slot antenna couples the patch antenna with microstripline through an aperture.

  10. Multigait soft robot.

    Science.gov (United States)

    Shepherd, Robert F; Ilievski, Filip; Choi, Wonjae; Morin, Stephen A; Stokes, Adam A; Mazzeo, Aaron D; Chen, Xin; Wang, Michael; Whitesides, George M

    2011-12-20

    This manuscript describes a unique class of locomotive robot: A soft robot, composed exclusively of soft materials (elastomeric polymers), which is inspired by animals (e.g., squid, starfish, worms) that do not have hard internal skeletons. Soft lithography was used to fabricate a pneumatically actuated robot capable of sophisticated locomotion (e.g., fluid movement of limbs and multiple gaits). This robot is quadrupedal; it uses no sensors, only five actuators, and a simple pneumatic valving system that operates at low pressures (< 10 psi). A combination of crawling and undulation gaits allowed this robot to navigate a difficult obstacle. This demonstration illustrates an advantage of soft robotics: They are systems in which simple types of actuation produce complex motion.

  11. Jacobi-Bessel analysis of reflector antennas with elliptical apertures

    Science.gov (United States)

    Rahmat-Samii, Yahya

    1987-01-01

    Although many reflector antennas possess circular projected apertures, there are recent satellite and ground antenna applications for which it is desirable to employ reflectors with elliptical apertures. Here a modification of the Jacobi-Bessel expansion is presented for the diffraction analysis of reflectors with elliptical apertures. A comparative study is also performed between this modified Jacobi-Bessel algorithm and the one which uses the Jacobi-Bessel expansion over a circumscribing circular region. Numerical results are presented for offset reflectors with elliptical and circular apertures and the improved convergence properties of the modified algorithm are highlighted.

  12. A statistical model for the excitation of cavities through apertures

    CERN Document Server

    Gradoni, Gabriele; Anlage, Steven M; Ott, Edward

    2015-01-01

    In this paper, a statistical model for the coupling of electromagnetic radiation into enclosures through apertures is presented. The model gives a unified picture bridging deterministic theories of aperture radiation, and statistical models necessary for capturing the properties of irregular shaped enclosures. A Monte Carlo technique based on random matrix theory is used to predict and study the power transmitted through the aperture into the enclosure. Universal behavior of the net power entering the aperture is found. Results are of interest for predicting the coupling of external radiation through openings in irregular enclosures and reverberation chambers.

  13. Optical Phase Imaging Using Synthetic Aperture Illumination and Phase Retrieval

    CERN Document Server

    Lee, Dennis J

    2016-01-01

    We perform quantitative phase imaging using phase retrieval to implement synthetic aperture imaging. Compared to digital holography, the developed technique is simpler, less expensive, and more stable.

  14. Facial Soft Tissue Trauma

    OpenAIRE

    Kretlow, James D.; McKnight, Aisha J.; Izaddoost, Shayan A.

    2010-01-01

    Traumatic facial soft tissue injuries are commonly encountered in the emergency department by plastic surgeons and other providers. Although rarely life-threatening, the treatment of these injuries can be complex and may have significant impact on the patient's facial function and aesthetics. This article provides a review of the relevant literature related to this topic and describes the authors' approach to the evaluation and management of the patient with facial soft tissue injuries.

  15. Soft tissue elastometer

    OpenAIRE

    Egorov, V.; Tsyuryupa, S.; Kanilo, S.; Kogit, M.; Sarvazyan, A.

    2007-01-01

    We have developed a device entitled the ‘Tissue Elastometer’ (TE) for evaluating the Young’s modulus of soft tissues. Soft tissue specimens are compressed between the object plate of an electronic balance and a linearly actuated indenter with a small rounded tip. The hardware of the device was designed such that a deformation model for semi-infinite media is applicable for calculating the Young’s modulus of test specimens from their collected force–displacement data.

  16. Soft tissue tumours.

    OpenAIRE

    Hayes, A J; Thomas, J M

    1997-01-01

    Any soft tissue swelling beneath the deep fascia should be considered a sarcoma until proven otherwise. As the most important factor in the primary treatment of these cancers is the adequacy of the primary surgical resection, it is vital to diagnose these malignant tumours pre-operatively. The modern treatment of soft tissue sarcomas may involve all modalities, but the most important aspect of treatment of a primary localised sarcoma is wide excisional surgery preserving limb function. Radiot...

  17. Deployable Soft Composite Structures

    OpenAIRE

    Wei Wang; Hugo Rodrigue; Sung-Hoon Ahn

    2016-01-01

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and sim...

  18. Dynamics of Soft Matter

    CERN Document Server

    García Sakai, Victoria; Chen, Sow-Hsin

    2012-01-01

    Dynamics of Soft Matter: Neutron Applications provides an overview of neutron scattering techniques that measure temporal and spatial correlations simultaneously, at the microscopic and/or mesoscopic scale. These techniques offer answers to new questions arising at the interface of physics, chemistry, and biology. Knowledge of the dynamics at these levels is crucial to understanding the soft matter field, which includes colloids, polymers, membranes, biological macromolecules, foams, emulsions towards biological & biomimetic systems, and phenomena involving wetting, friction, adhesion, or micr

  19. Oligarchy and soft incompleteness

    OpenAIRE

    Piggins, Ashley; Duddy, Conal

    2016-01-01

    The assumption that the social preference relation is complete is demanding. We distinguish between “hard” and “soft” incompleteness, and explore the social choice implications of the latter. Under soft incompleteness, social preferences can take values in the unit interval. We motivate interest in soft incompleteness by presenting a version of the strong Pareto rule that is suited to the context of a [0, 1]-valued social preference relation. Using a novel approach to the quasi-tr...

  20. Mechanochemically Active Soft Robots.

    Science.gov (United States)

    Gossweiler, Gregory R; Brown, Cameron L; Hewage, Gihan B; Sapiro-Gheiler, Eitan; Trautman, William J; Welshofer, Garrett W; Craig, Stephen L

    2015-10-14

    The functions of soft robotics are intimately tied to their form-channels and voids defined by an elastomeric superstructure that reversibly stores and releases mechanical energy to change shape, grip objects, and achieve complex motions. Here, we demonstrate that covalent polymer mechanochemistry provides a viable mechanism to convert the same mechanical potential energy used for actuation in soft robots into a mechanochromic, covalent chemical response. A bis-alkene functionalized spiropyran (SP) mechanophore is cured into a molded poly(dimethylsiloxane) (PDMS) soft robot walker and gripper. The stresses and strains necessary for SP activation are compatible with soft robot function. The color change associated with actuation suggests opportunities for not only new color changing or camouflaging strategies, but also the possibility for simultaneous activation of latent chemistry (e.g., release of small molecules, change in mechanical properties, activation of catalysts, etc.) in soft robots. In addition, mechanochromic stress mapping in a functional robotic device might provide a useful design and optimization tool, revealing spatial and temporal force evolution within the robot in a way that might be coupled to autonomous feedback loops that allow the robot to regulate its own activity. The demonstration motivates the simultaneous development of new combinations of mechanophores, materials, and soft, active devices for enhanced functionality. PMID:26390078

  1. Femoral Aperture Fixation Improves Anterior Cruciate Ligament Graft Function When Added to Cortical Suspensory Fixation

    Science.gov (United States)

    Porter, Mark D.; Shadbolt, Bruce

    2016-01-01

    Background: Recommendations for bone tunnel placement during anterior cruciate ligament (ACL) reconstruction have become more precise. However, these recommendations differ neither with the choice of graft nor with the method of fixation used. The influence of the method of femoral fixation used on the biomechanical function of a soft tissue ACL graft remains unknown. Hypothesis: Our null hypothesis was that adding femoral aperture fixation to femoral cortical fixation, using the same bone tunnels, will not alter the control of anterior translation (AT) and internal rotation (IR) during ACL reconstruction using a hamstring graft. Study Design: Controlled laboratory study. Methods: A total of 22 patients with an acute isolated ACL rupture underwent reconstruction using a single-bundle autologous hamstring graft. Computer navigation was used intraoperatively to plot the AT and IR during the pivot-shift test before reconstruction, after ACL reconstruction using cortical suspensory fixation, and after the addition of femoral aperture fixation. Statistical analysis (analysis of variance) was used to compare the AT and IR during the pivot shift at each stage in the procedure. Results: Before ACL reconstruction, the mean (±SD) AT was 14.2 ± 7.3 mm and mean IR was 17.2° ± 5.5°. After reconstruction using femoral cortical suspension, these figures were significantly reduced to 6.2 ± 3.5 mm and 12.5° ± 3.20°, respectively (P < .001). The addition of the aperture fixation was associated with a further significant reduction to 4.6 ± 3.2 mm and 10.4° ± 2.7°, respectively (P < .001). Conclusion: The addition of femoral aperture fixation to suspensory fixation results in a significant reduction in both the AT and IR that occurs during the pivot-shift assessment immediately after ACL reconstruction using autologous hamstring graft. Clinical Relevance: The most precise positioning of bone tunnels during soft tissue ACL reconstruction needs to take into consideration

  2. Femoral Aperture Fixation Improves Anterior Cruciate Ligament Graft Function When Added to Cortical Suspensory Fixation

    Science.gov (United States)

    Porter, Mark D.; Shadbolt, Bruce

    2016-01-01

    Background: Recommendations for bone tunnel placement during anterior cruciate ligament (ACL) reconstruction have become more precise. However, these recommendations differ neither with the choice of graft nor with the method of fixation used. The influence of the method of femoral fixation used on the biomechanical function of a soft tissue ACL graft remains unknown. Hypothesis: Our null hypothesis was that adding femoral aperture fixation to femoral cortical fixation, using the same bone tunnels, will not alter the control of anterior translation (AT) and internal rotation (IR) during ACL reconstruction using a hamstring graft. Study Design: Controlled laboratory study. Methods: A total of 22 patients with an acute isolated ACL rupture underwent reconstruction using a single-bundle autologous hamstring graft. Computer navigation was used intraoperatively to plot the AT and IR during the pivot-shift test before reconstruction, after ACL reconstruction using cortical suspensory fixation, and after the addition of femoral aperture fixation. Statistical analysis (analysis of variance) was used to compare the AT and IR during the pivot shift at each stage in the procedure. Results: Before ACL reconstruction, the mean (±SD) AT was 14.2 ± 7.3 mm and mean IR was 17.2° ± 5.5°. After reconstruction using femoral cortical suspension, these figures were significantly reduced to 6.2 ± 3.5 mm and 12.5° ± 3.20°, respectively (P < .001). The addition of the aperture fixation was associated with a further significant reduction to 4.6 ± 3.2 mm and 10.4° ± 2.7°, respectively (P < .001). Conclusion: The addition of femoral aperture fixation to suspensory fixation results in a significant reduction in both the AT and IR that occurs during the pivot-shift assessment immediately after ACL reconstruction using autologous hamstring graft. Clinical Relevance: The most precise positioning of bone tunnels during soft tissue ACL reconstruction needs to take into consideration

  3. Operations on soft sets revisited

    CERN Document Server

    Zhu, Ping

    2012-01-01

    Soft sets, as a mathematical tool for dealing with uncertainty, have recently gained considerable attention, including some successful applications in information processing, decision, demand analysis, and forecasting. To construct new soft sets from given soft sets, some operations on soft sets have been proposed. Unfortunately, such operations cannot keep all classical set-theoretic laws true for soft sets. In this paper, we redefine the intersection, complement, and difference of soft sets and investigate the algebraic properties of these operations along with a known union operation. We find that the new operation system on soft sets inherits all basic properties of operations on classical sets, which justifies our definitions.

  4. Wind energy applications of synthetic aperture radar

    DEFF Research Database (Denmark)

    Badger, Merete

    planning as a supplement to on site measurements, which are costly and sparse, and model wind fields, which are not fully validated. Two applications of SAR measurements in offshore wind energy planning areaddressed here: the study of wind farm wake effects and the potential of using SAR winds in offshore......Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting windfields are valuable in offshore wind energy...... in offshore wind resource assessment isinvestigated. The resource assessment is made through Weibull fitting to frequency observations of wind speed and requires at least 100 satellite observations per year for a given site of interest. Predictions of the energy density are very sensitive tothe wind speed...

  5. Ultrasonic synthetic aperture imaging of defects

    International Nuclear Information System (INIS)

    Current reactor systems have been generally designed with limited facility for in-service inspection. Where ultrasonic crack detection and sizing techniques have been applied they appear to be functioning adequately. The purpose of this paper is to introduce a modification to conventional ultrasonic defect sizing which yields acoustic measurements of the dimensions of the defect in its plane parallel to the inspection surface. The technique retains the simplicity of a single probe to collect data, but achieves the effect of multidepth focussing by a particular signal processing procedure. The subject is discussed under the headings: ultrasonic focussing procedures; the basic principle of linear synthetic aperture focussing; the mechanics of the system; the capability of the system; comments and conclusion. (U.K.)

  6. Mathematical Problems in Synthetic Aperture Radar

    CERN Document Server

    Klein, Jens

    2010-01-01

    This thesis is concerned with problems related to Synthetic Aperture Radar (SAR). The thesis is structured as follows: The first chapter explains what SAR is, and the physical and mathematical background is illuminated. The following chapter points out a problem with a divergent integral in a common approach and proposes an improvement. Numerical comparisons are shown that indicate that the improvements allow for a superior image quality. Thereafter the problem of limited data is analyzed. In a realistic SAR-measurement the data gathered from the electromagnetic waves reflected from the surface can only be collected from a limited area. However the reconstruction formula requires data from an infinite distance. The chapter gives an analysis of the artifacts which can obscure the reconstructed images due to this problem. Additionally, some numerical examples are shown that point to the severity of the problem. In chapter 4 the fact that data is available only from a limited area is used to propose a new invers...

  7. Terahertz Imaging Systems With Aperture Synthesis Techniques

    DEFF Research Database (Denmark)

    Krozer, Viktor; Löffler, Torsten; Dall, Jørgen;

    2010-01-01

    This paper presents the research and development of two terahertz imaging systems based on photonic and electronic principles, respectively. As part of this study, a survey of ongoing research in the field of terahertz imaging is provided focusing on security applications. Existing terahertz...... imaging systems are reviewed in terms of the employed architecture and data processing strategies. Active multichannel measurement method is found to be promising for real-time applications among the various terahertz imaging techniques and is chosen as a basis for the imaging instruments presented...... in this paper. An active system operation allows for a wide dynamic range, which is important for image quality. The described instruments employ a multichannel high-sensitivity heterodyne architecture and aperture filling techniques, with close to real-time image acquisition time. In the case of the photonic...

  8. Light-Regulated Stomatal Aperture in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Chen Chen; Yu-Guo Xiao; Xin Li; Min Ni

    2012-01-01

    The stomatal pores of plant leaves,situated in the epidermis and surrounded by a pair of guard cells,allow CO2 uptake for photosynthesis and water loss through transpiration.Blue light is one of the dominant environmental signals that control stomatal movements in leaves of plants in a natural environment.This blue light response is mediated by blue/UV A light-absorbing phototropins (phots) and cryptochromes (crys).Red/far-red light-absorbing phytochromes (phys) also play a role in the control of stomatal aperture.The signaling components that link the perception of light signals to the stomatal opening response are largely unknown.This review discusses a few newly discovered nuclear genes,their function with respect to the phot-,cry-,and phy-mediated signal transduction cascades,and possible involvement of circadian clock.

  9. Large aperture nanocomposite deformable mirror technology

    Science.gov (United States)

    Chen, Peter C.; Hale, Richard D.

    2007-12-01

    We report progress in the development of deformable mirrors (DM) using nanocomposite materials. For the extremely large telescopes (ELTs) currently being planned, a new generation of DMs with unprecedented performance is a critical path item. The DMs need to have large apertures (meters), continuous surfaces, and low microroughness. Most importantly, they must have excellent static optical figures and yet be sufficiently thin (1-2 mm) and flexible to function with small, low powered actuators. Carbon fiber reinforced plastics (CFRP) have the potential to fulfill these requirements. However, CFRP mirrors made using direct optical replication have encountered a number of problems. Firstly, it is difficult if not impossible for a CFRP mirror to maintain a good static optical figure if a small number of plies are used, but adding more plies to the laminate tends to make the substrate too thick and stiff. Secondly, direct optical replication requires precision mandrels, the costs of which become prohibitive at multi-meter apertures. We report development of a new approach. By using a combination of a novel support structure, selected fibers, and binding resins infused with nanoparticles, it is possible to make millimeter thick optical mirrors that can both maintain good static optical figures and yet still have the required flexibility for actuation. Development and refinement of a non-contact, deterministic process of fine figuring permits generation of accurate optical surfaces without the need for precision optical mandrels. We present data from tests that have been carried out to demonstrate these new processes. A number of flat DMs have been fabricated, as well as concave and convex DMs in spherical, parabolic, and other forms.

  10. People bouncing on trampolines: dramatic energy transfer, a table-top demonstration, complex dynamics and a zero sum game.

    Directory of Open Access Journals (Sweden)

    Manoj Srinivasan

    Full Text Available Jumping on trampolines is a popular backyard recreation. In some trampoline games (e.g., "seat drop war", when two people land on the trampoline with only a small time-lag, one person bounces much higher than the other, as if energy has been transferred from one to the other. First, we illustrate this energy-transfer in a table-top demonstration, consisting of two balls dropped onto a mini-trampoline, landing almost simultaneously, sometimes resulting in one ball bouncing much higher than the other. Next, using a simple mathematical model of two masses bouncing passively on a massless trampoline with no dissipation, we show that with specific landing conditions, it is possible to transfer all the kinetic energy of one mass to the other through the trampoline - in a single bounce. For human-like parameters, starting with equal energy, the energy transfer is maximal when one person lands approximately when the other is at the bottom of her bounce. The energy transfer persists even for very stiff surfaces. The energy-conservative mathematical model exhibits complex non-periodic long-term motions. To complement this passive bouncing model, we also performed a game-theoretic analysis, appropriate when both players are acting strategically to steal the other player's energy. We consider a zero-sum game in which each player's goal is to gain the other player's kinetic energy during a single bounce, by extending her leg during flight. For high initial energy and a symmetric situation, the best strategy for both subjects (minimax strategy and Nash equilibrium is to use the shortest available leg length and not extend their legs. On the other hand, an asymmetry in initial heights allows the player with more energy to gain even more energy in the next bounce. Thus synchronous bouncing unstable is unstable both for passive bouncing and when leg lengths are controlled as in game-theoretic equilibria.

  11. Synthetic Aperture Sequential Beamformation applied to medical imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is applied to medical ultrasound imaging using a multi element convex array transducer. The main motivation for SASB is to apply synthetic aperture techniques without the need for storing RF-data for a number of elements and hereby devise a system...

  12. Apparatus and method for velocity estimation in synthetic aperture imaging

    DEFF Research Database (Denmark)

    2003-01-01

    The invention relates to an apparatus for flow estimation using synthetic aperture imaging. The method uses a Synthetic Transmit Aperture, but unlike previous approaches a new frame is created after every pulse emission. In receive mode parallel beam forming is implemented. The beam formed RF data...

  13. Second harmonic imaging using synthetic aperture sequential beamforming

    DEFF Research Database (Denmark)

    Du, Yigang; Rasmussen, Joachim; Jensen, Henrik;

    2011-01-01

    The paper investigates Second Harmonic Imaging (SHI) using Synthetic Aperture Sequential Beamforming (SASB). The investigation is made by an experimental Synthetic Aperture Real-time Ultrasound System (SARUS). A linear array transducer is used to scan 4 wires at the image depths of f22.5, 47.5, 72...

  14. Velocity estimation using synthetic aperture imaging [blood flow

    OpenAIRE

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a fully functioning synthetic aperture scanner can be made

  15. The sonar aperture and its neural representation in bats.

    Science.gov (United States)

    Heinrich, Melina; Warmbold, Alexander; Hoffmann, Susanne; Firzlaff, Uwe; Wiegrebe, Lutz

    2011-10-26

    As opposed to visual imaging, biosonar imaging of spatial object properties represents a challenge for the auditory system because its sensory epithelium is not arranged along space axes. For echolocating bats, object width is encoded by the amplitude of its echo (echo intensity) but also by the naturally covarying spread of angles of incidence from which the echoes impinge on the bat's ears (sonar aperture). It is unclear whether bats use the echo intensity and/or the sonar aperture to estimate an object's width. We addressed this question in a combined psychophysical and electrophysiological approach. In three virtual-object playback experiments, bats of the species Phyllostomus discolor had to discriminate simple reflections of their own echolocation calls differing in echo intensity, sonar aperture, or both. Discrimination performance for objects with physically correct covariation of sonar aperture and echo intensity ("object width") did not differ from discrimination performances when only the sonar aperture was varied. Thus, the bats were able to detect changes in object width in the absence of intensity cues. The psychophysical results are reflected in the responses of a population of units in the auditory midbrain and cortex that responded strongest to echoes from objects with a specific sonar aperture, regardless of variations in echo intensity. Neurometric functions obtained from cortical units encoding the sonar aperture are sufficient to explain the behavioral performance of the bats. These current data show that the sonar aperture is a behaviorally relevant and reliably encoded cue for object size in bat sonar.

  16. Shadow Enhancement in Synthetic Aperture Sonar Using Fixed Focusing

    NARCIS (Netherlands)

    Groen, J.; Hansen, R.E.; Callow, H.J.; Sabel, J.C.; Sæbø, T.O.

    2009-01-01

    Abstract—A shadow cast by an object on the seafloor is important information for target recognition in synthetic aperture sonar (SAS) images. Synthetic aperture imaging causes a fundamental limitation to shadow clarity because the illuminator is moved during the data collection. This leads to a blen

  17. SARUS: A Synthetic Aperture Real-Time Ultrasound System

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Holten-Lund, Hans; Nilsson, Ronnie Thorup;

    2013-01-01

    The Synthetic Aperture Real-time Ultrasound System (SARUS) for acquiring and processing synthetic aperture (SA) data for research purposes is described. The specifications and design of the system are detailed, along with its performance for SA, nonlinear, and 3-D flow estimation imaging. SARUS...

  18. Characteristics of Electromagnetic Pulse Coupling into Annular Apertures

    Directory of Open Access Journals (Sweden)

    Yan-Peng Sun

    2013-11-01

    Full Text Available Electromagnetic pulse (EMP coupling into the annular apertures can disturb or damage much electronic equipment. To enhance electronic system’s  capability of anti-electromagnetic interference, the finite difference time domain method (FDTD was employed to study the characteristics of electromagnetic pulse coupling into the cavity enclosures with annular apertures. The coupling characteristics of annular apertures with different shapes (rectangle, square and circle were discussed. It shows that, in the case of the same aperture area, the coupling energy of electromagnetic pulse into the circular annular aperture is smaller than that into the rectangular and the square ones. To the rectangular annular aperture, while the polarization direction of the incident electromagnetic pulse is perpendicular to the long side of the rectangular annular aperture, the coupling energy is larger when the aspect ratio of the rectangular annular aperture is larger. The coupling effect of incident pulse with short pulse width is obviously better than the one with longer pulse width. The resonance phenomenon of the coupled waveform occurs in the cavity.

  19. Calculation on diffraction aperture of cube corner retroreflector

    Institute of Scientific and Technical Information of China (English)

    Song Li; Bei Tang; Hui Zhou

    2008-01-01

    On the basis of optical property of cube corner retroreflector (CCR), a new perception and calculation approach for diffraction aperture of CCR in two different forms is presented. The relationship between diffraction apertures and incident light with six different combinations of reflection order and incident angle is established. Far-field diffraction patterns of CCR under various incident conditions are also provided.

  20. Generation of high-photon flux-coherent soft x-ray radiation with few-cycle pulses.

    Science.gov (United States)

    Demmler, Stefan; Rothhardt, Jan; Hädrich, Steffen; Krebs, Manuel; Hage, Arvid; Limpert, Jens; Tünnermann, Andreas

    2013-12-01

    We present a tabletop source of coherent soft x-ray radiation with high-photon flux. Two-cycle pulses delivered by a fiber-laser-pumped optical parametric chirped-pulse amplifier operating at 180 kHz repetition rate are upconverted via high harmonic generation in neon to photon energies beyond 200 eV. A maximum photon flux of 1.3·10(8) photons/s is achieved within a 1% bandwidth at 125 eV photon energy. This corresponds to a conversion efficiency of ~10(-9), which can be reached due to a gas jet simultaneously providing a high target density and phase matching. Further scaling potential toward higher photon flux as well as higher photon energies are discussed.

  1. Generation of high-photon flux-coherent soft x-ray radiation with few-cycle pulses.

    Science.gov (United States)

    Demmler, Stefan; Rothhardt, Jan; Hädrich, Steffen; Krebs, Manuel; Hage, Arvid; Limpert, Jens; Tünnermann, Andreas

    2013-12-01

    We present a tabletop source of coherent soft x-ray radiation with high-photon flux. Two-cycle pulses delivered by a fiber-laser-pumped optical parametric chirped-pulse amplifier operating at 180 kHz repetition rate are upconverted via high harmonic generation in neon to photon energies beyond 200 eV. A maximum photon flux of 1.3·10(8) photons/s is achieved within a 1% bandwidth at 125 eV photon energy. This corresponds to a conversion efficiency of ~10(-9), which can be reached due to a gas jet simultaneously providing a high target density and phase matching. Further scaling potential toward higher photon flux as well as higher photon energies are discussed. PMID:24281507

  2. Synthetic aperture radar imaging with motion estimation and autofocus

    International Nuclear Information System (INIS)

    We introduce from first principles a synthetic aperture radar (SAR) imaging and target motion estimation method that is combined with compensation for radar platform trajectory perturbations. The main steps of the method are (a) segmentation of the data into properly calibrated small apertures, (b) motion or platform trajectory perturbation estimation using the Wigner transform and the ambiguity function of the data in a complementary way and (c) combination of small aperture estimates and construction of high-resolution images over wide apertures. The analysis provides quantitative criteria for implementing the aperture segmentation and the parameter estimation process. X-band persistent surveillance SAR is a specific application that is covered by our analysis. Detailed numerical simulations illustrate the robust applicability of the theory and validate the theoretical resolution analysis. (paper)

  3. Microfabricated high-bandpass foucault aperture for electron microscopy

    Science.gov (United States)

    Glaeser, Robert; Cambie, Rossana; Jin, Jian

    2014-08-26

    A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

  4. Coded Aperture Imaging for Fluorescent X-rays-Biomedical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Haboub, Abdel; MacDowell, Alastair; Marchesini, Stefano; Parkinson, Dilworth

    2013-06-01

    Employing a coded aperture pattern in front of a charge couple device pixilated detector (CCD) allows for imaging of fluorescent x-rays (6-25KeV) being emitted from samples irradiated with x-rays. Coded apertures encode the angular direction of x-rays and allow for a large Numerical Aperture x- ray imaging system. The algorithm to develop the self-supported coded aperture pattern of the Non Two Holes Touching (NTHT) pattern was developed. The algorithms to reconstruct the x-ray image from the encoded pattern recorded were developed by means of modeling and confirmed by experiments. Samples were irradiated by monochromatic synchrotron x-ray radiation, and fluorescent x-rays from several different test metal samples were imaged through the newly developed coded aperture imaging system. By choice of the exciting energy the different metals were speciated.

  5. Soft and Ultra-soft Elastomers

    Science.gov (United States)

    Daniel, William; Burdynska, Joanna; Kirby, Sam; Zhou, Yang; Matyjaszewski, Krzysztof; Rubinstein, Michael; Sheiko, Sergei; UNC-MIRT Team

    2014-03-01

    Polymeric networks are attractive engineering materials utilized for various mechanically demanding applications. As such, much attention has been paid to reinforcement of polymer mechanical properties with little interest in how to make softer elastomers to address numerous biomedical applications including implants and cell differentiation. Without swelling in a solvent, it is challenging to obtain materials with a modulus below ca.105 Pa, which is dictated by chain entanglements. Here we present two methodologies for the creation of soft and ultra-soft dry elastomeric compounds. The first method utilizes polymer capsules as temperature responsive filler. Depending on volume fraction of microcapsules this method is capable of fine tuning modulus within an order of magnitude. The second technique uses the densely grafted molecular brush architecture to create solvent-free polymer melts and elastomers with plateau moduli in the range one hundred to ten hundred Pa. Such compounds may find uses in biomedical applications including reconstructive surgery and cell differentiation. National Science Foundation DMR-1122483.

  6. Introductory physics going soft

    Science.gov (United States)

    Langbeheim, Elon; Livne, Shelly; Safran, Samuel A.; Yerushalmi, Edit

    2012-01-01

    We describe an elective course on soft matter at the level of introductory physics. Soft matter physics serves as a context that motivates the presentation of basic ideas in statistical thermodynamics and their applications. It also is an example of a contemporary field that is interdisciplinary and touches on chemistry, biology, and physics. We outline a curriculum that uses the lattice gas model as a quantitative and visual tool, initially to introduce entropy, and later to facilitate the calculation of interactions. We demonstrate how free energy minimization can be used to teach students to understand the properties of soft matter systems such as the phases of fluid mixtures, wetting of interfaces, self-assembly of surfactants, and polymers. We discuss several suggested activities in the form of inquiry projects which allow students to apply the concepts they have learned to experimental systems.

  7. Tensional acoustomechanical soft metamaterials

    Science.gov (United States)

    Xin, Fengxian; Lu, Tianjian

    2016-06-01

    We create acoustomechanical soft metamaterials whose response to uniaxial tensile stressing can be easily tailored by programming acoustic wave inputs, resulting in force versus stretch curves that exhibit distinct monotonic, s-shape, plateau and non-monotonic snapping behaviors. We theoretically demonstrate this unique metamaterial by considering a thin soft material sheet impinged by two counter-propagating ultrasonic wave inputs across its thickness and stretched by an in-plane uniaxial tensile force. We establish a theoretical acoustomechanical model to describe the programmable mechanics of such soft metamaterial, and introduce the first- and second-order tangential stiffness of its force versus stretch curve to boundary different behaviors that appear during deformation. The proposed phase diagrams for the underlying nonlinear mechanics show promising prospects for designing tunable and switchable photonic/phononic crystals and microfluidic devices that harness snap-through instability.

  8. Results on fuzzy soft topological spaces

    OpenAIRE

    J Mahanta; P. K. Das

    2012-01-01

    B. Tanay et. al. introduced and studied fuzzy soft topological spaces. Here we introduce fuzzy soft point and study the concept of neighborhood of a fuzzy soft point in a fuzzy soft topological space. We also study fuzzy soft closure and fuzzy soft interior. Separation axioms and connectedness are introduced and investigated for fuzzy soft topological spaces.

  9. Mechanics of soft materials

    CERN Document Server

    Volokh, Konstantin

    2016-01-01

    This book provides a concise introduction to soft matter modelling. It offers an up-to-date review of continuum mechanical description of soft and biological materials from the basics to the latest scientific materials. It includes multi-physics descriptions, such as chemo-, thermo-, electro- mechanical coupling. It derives from a graduate course at Technion that has been established in recent years. It presents original explanations for some standard materials and features elaborated examples on all topics throughout the text. PowerPoint lecture notes can be provided to instructors. .

  10. Some Properties of Fuzzy Soft Proximity Spaces

    OpenAIRE

    İzzettin Demir; Oya Bedre Özbakır

    2015-01-01

    We study the fuzzy soft proximity spaces in Katsaras’s sense. First, we show how a fuzzy soft topology is derived from a fuzzy soft proximity. Also, we define the notion of fuzzy soft δ-neighborhood in the fuzzy soft proximity space which offers an alternative approach to the study of fuzzy soft proximity spaces. Later, we obtain the initial fuzzy soft proximity determined by a family of fuzzy soft proximities. Finally, we investigate relationship between fuzzy soft proximities and proximiti...

  11. Fracture-aperture alteration induced by calcite precipitation

    Science.gov (United States)

    Jones, T.; Detwiler, R. L.

    2013-12-01

    Mineral precipitation significantly alters the transport properties of fractured rock. Chemical solubility gradients that favor precipitation induce mineral growth, which decreases the local aperture and alters preferential flow paths. Understanding the resulting development of spatial heterogeneities is necessary to predict the evolution of transport properties in the subsurface. We present experimental results that quantify the relationship between mineral precipitation and aperture alteration in a transparent analog fracture, 7.62cm x 7.62cm, with a uniform aperture of ~200 μm. Prior to flow experiments, a pump circulated a super-saturated calcite solution over the bottom glass, coating the glass surface with calcite. This method of seeding resulted in clusters of calcite crystals with large reactive surface area and provided micro-scale variability in the aperture field. A continuous flow syringe pump injected a reactive fluid into the fracture at 0.5 ml/min. The fluid was a mixture of sodium bicarbonate (NaHCO3, 0.02M) and calcium chloride (CaCl2 0.0004M) with a saturation index, Ω, of 8.51 with respect to calcite. A strobed LED panel backlit the fracture and a high-resolution CCD camera monitored changes in transmitted light intensity. Light transmission techniques provided a quantitative measurement of fracture aperture over the flow field. Results from these preliminary experiments showed growth near the inlet of the fracture, with decreasing precipitation rates in the flow direction. Over a period of two weeks, the fracture aperture decreased by 17% within the first 4mm of the inlet. Newly precipitated calcite bridged individual crystal clusters and smoothed the reacting surface. This observation is an interesting contradiction to the expectation of surface roughening induced by mineral growth. Additionally, the aperture decreased uniformly across the width of the fracture due to the initial aperture distribution. Future experiments of precipitation

  12. Stereoscopic full aperture imaging in nuclear medicine

    Directory of Open Access Journals (Sweden)

    Sergio G. Strocovsky

    2011-06-01

    Full Text Available Images of planar scintigraphy and single photon emission computerized tomography (SPECT used in nuclear medicine are often low quality. They usually appear to be blurred and noisy. This problem is due to the low spatial resolution and poor sensitivity of the acquisition technique with the gamma camera (GC. Other techniques, such as coded aperture imaging (CAI reach higher spatial resolutions than GC. However, CAI is not frequently used for imaging in nuclear medicine, due to the decoding complexity of some images and the difficulty in controlling the noise magnitude. Summing up, the images obtained through GC are low quality and it is still difficult to implement CAI technique. A novel technique, full aperture Imaging (FAI, also uses gamma ray-encoding to obtain images, but the coding system and the method of images reconstruction are simpler than those used in CAI. In addition, FAI also reaches higher spatial resolution than GC. In this work, the principles of FAI technique and the method of images reconstruction are explained in detail. The FAI technique is tested by means of Monte Carlo simulations with filiform and spherical sources. Spatial resolution tests of GC versus FAI were performed using two different source-detector distances. First, simulations were made without interposing any material between the sources and the detector. Then, other more realistic simulations were made. In these, the sources were placed in the centre of a rectangular prismatic region, filled with water. A rigorous comparison was made between GC and FAI images of the linear filiform sources, by means of two methods: mean fluence profile graphs and correlation tests. Finally, three-dimensional capacity of FAI was tested with two spherical sources. The results show that FAI technique has greater sensitivity (>100 times and greater spatial resolution (>2.6 times than that of GC with LEHR collimator, in both cases, with and without attenuating material and long and

  13. The Design, Implementation, and Performance of the Astro-H SXS Aperture Assembly and Blocking Filters

    Science.gov (United States)

    Kilbourne, Caroline A.; Adams, Joseph S.; Arsenovic, Petar; Ayers, Travis; Chiao, Meng P.; DiPirro, Michael J.; Eckart, Megan E.; Fujimoto, Ryuichi; Kazeva, John D.; Kelley, Richard L.; Kripps, Kari L.; Lairson, Bruce; Leutenegger, Maurice A.; McGuinness, Daniel S.; Porter, F. Scott; Schweiss, Andrea N.

    2016-01-01

    The calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The properties that make the SXS array a powerful x-ray spectrometer also make it sensitive to photons from the entire electromagnetic band, and particles as well. If characterized as a bolometer, it would have a noise equivalent power (NEP) of less than 4x10(exp -18) W/(Hz)0.5(exp 0.5). Thus it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. Additionally, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. Both of these needs are addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that block long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly is a system of barriers, baffles, filter carriers, and filter mounts that supports the filters and inhibits their potential contamination. The three outer filters also have been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.

  14. Detection of breast microcalcifications using synthetic-aperture ultrasound

    Science.gov (United States)

    Huang, Lianjie; Labyed, Yassin; Lin, Youzuo; Zhang, Zhigang; Pohl, Jennifer; Sandoval, Daniel; Williamson, Michael

    2012-03-01

    Ultrasound could be an attractive imaging modality for detecting breast microcalcifications, but it requires significant improvement in image resolution and quality. Recently, we have used tissue-equivalent phantoms to demonstrate that synthetic-aperture ultrasound has the potential to detect small targets. In this paper, we study the in vivo imaging capability of a real-time synthetic-aperture ultrasound system for detecting breast microcalcifications. This LANL's (Los Alamos National Laboratory's) custom built synthetic-aperture ultrasound system has a maximum frame rate of 25 Hz, and is one of the very first medical devices capable of acquiring synthetic-aperture ultrasound data and forming ultrasound images in real time, making the synthetic-aperture ultrasound feasible for clinical applications. We recruit patients whose screening mammograms show breast microcalcifications, and use LANL's synthetic-aperture ultrasound system to scan the regions with microcalcifications. Our preliminary in vivo patient imaging results demonstrate that synthetic-aperture ultrasound is a promising imaging modality for detecting breast microcalcifications.

  15. Preliminary comparison of 3D synthetic aperture imaging with Explososcan

    Science.gov (United States)

    Rasmussen, Morten Fischer; Hansen, Jens Munk; Férin, Guillaume; Dufait, Rémi; Jensen, Jørgen Arendt

    2012-03-01

    Explososcan is the 'gold standard' for real-time 3D medical ultrasound imaging. In this paper, 3D synthetic aperture imaging is compared to Explososcan by simulation of 3D point spread functions. The simulations mimic a 32×32 element prototype transducer. The transducer mimicked is a dense matrix phased array with a pitch of 300 μm, made by Vermon. For both imaging techniques, 289 emissions are used to image a volume spanning 60° in both the azimuth and elevation direction and 150mm in depth. This results for both techniques in a frame rate of 18 Hz. The implemented synthetic aperture technique reduces the number of transmit channels from 1024 to 256, compared to Explososcan. In terms of FWHM performance, was Explososcan and synthetic aperture found to perform similar. At 90mm depth is Explososcan's FWHM performance 7% better than that of synthetic aperture. Synthetic aperture improved the cystic resolution, which expresses the ability to detect anechoic cysts in a uniform scattering media, at all depths except at Explososcan's focus point. Synthetic aperture reduced the cyst radius, R20dB, at 90mm depth by 48%. Synthetic aperture imaging was shown to reduce the number of transmit channels by four and still, generally, improve the imaging quality.

  16. Synthetic aperture radar imaging exploiting multiple scattering

    International Nuclear Information System (INIS)

    In this paper, we consider an imaging scenario, where a bi-static synthetic aperture radar (SAR) system is used in a multiple scattering environment. We consider a ray-theoretic approximation to the Green function to model a multiple scattering environment. This allows us to incorporate the multiple paths followed by the transmitted signal, thereby providing different views of the object to be imaged. However, the received signal from the multiple paths and additive thermal noise may interfere and produce artifacts when standard backprojection-based reconstruction algorithms are used. We use microlocal analysis in a statistical setting to develop a novel filtered-backprojection type image reconstruction method that not only exploits the multi-paths leading to enhancement of the reconstructed image but also suppresses the artifacts due to interference. We assume a priori knowledge of the second-order statistics of the target and noise to suppress the artifacts due to interference in a mean-square error sense. We present numerical simulations to demonstrate the performance of our image reconstruction method. While the focus of this paper is on radar applications, our image formation method is also applicable to other problems arising in fields such as acoustic, geophysical and medical imaging

  17. Motion Measurement for Synthetic Aperture Radar.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.

    2015-01-01

    Synthetic Aperture Radar (SAR) measures radar soundings from a set of locations typically along the flight path of a radar platform vehicle. Optimal focusing requires precise knowledge of the sounding source locations in 3 - D space with respect to the target scene. Even data driven focusing techniques (i.e. autofocus) requires some degree of initial fidelity in the measurements of the motion of the radar. These requirements may be quite stringent especially for fine resolution, long ranges, and low velocities. The principal instrument for measuring motion is typically an Inertial Measurement Unit (IMU), but these instruments have inherent limi ted precision and accuracy. The question is %22How good does an IMU need to be for a SAR across its performance space?%22 This report analytically relates IMU specifications to parametric requirements for SAR. - 4 - Acknowledgements Th e preparation of this report is the result of a n unfunded research and development activity . Although this report is an independent effort, it draws heavily from limited - release documentation generated under a CRADA with General Atomics - Aeronautical System, Inc. (GA - ASI), and under the Joint DoD/DOE Munitions Program Memorandum of Understanding. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of En ergy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000.

  18. High numerical aperture multilayer Laue lenses.

    Science.gov (United States)

    Morgan, Andrew J; Prasciolu, Mauro; Andrejczuk, Andrzej; Krzywinski, Jacek; Meents, Alke; Pennicard, David; Graafsma, Heinz; Barty, Anton; Bean, Richard J; Barthelmess, Miriam; Oberthuer, Dominik; Yefanov, Oleksandr; Aquila, Andrew; Chapman, Henry N; Bajt, Saša

    2015-01-01

    The ever-increasing brightness of synchrotron radiation sources demands improved X-ray optics to utilise their capability for imaging and probing biological cells, nanodevices, and functional matter on the nanometer scale with chemical sensitivity. Here we demonstrate focusing a hard X-ray beam to an 8 nm focus using a volume zone plate (also referred to as a wedged multilayer Laue lens). This lens was constructed using a new deposition technique that enabled the independent control of the angle and thickness of diffracting layers to microradian and nanometer precision, respectively. This ensured that the Bragg condition is satisfied at each point along the lens, leading to a high numerical aperture that is limited only by its extent. We developed a phase-shifting interferometric method based on ptychography to characterise the lens focus. The precision of the fabrication and characterisation demonstrated here provides the path to efficient X-ray optics for imaging at 1 nm resolution. PMID:26030003

  19. Motion measurement for synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-01-01

    Synthetic Aperture Radar (SAR) measures radar soundings from a set of locations typically along the flight path of a radar platform vehicle. Optimal focusing requires precise knowledge of the sounding source locations in 3-D space with respect to the target scene. Even data driven focusing techniques (i.e. autofocus) requires some degree of initial fidelity in the measurements of the motion of the radar. These requirements may be quite stringent especially for fine resolution, long ranges, and low velocities. The principal instrument for measuring motion is typically an Inertial Measurement Unit (IMU), but these instruments have inherent limi ted precision and accuracy. The question is %22How good does an IMU need to be for a SAR across its performance space?%22 This report analytically relates IMU specifications to parametric requirements for SAR. - 4 - Acknowledgements Th e preparation of this report is the result of a n unfunded research and development activity . Although this report is an independent effort, it draws heavily from limited - release documentation generated under a CRADA with General Atomics - Aeronautical System, Inc. (GA - ASI), and under the Joint DoD/DOE Munitions Program Memorandum of Understanding. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of En ergy's National Nuclear Security Administration under contract AC04-94AL85000.

  20. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

    Andrei Yu Ivanov; Anna I Ginzburg

    2002-09-01

    Continuous observations since 1991 by using synthetic aperture radar (SAR) on board the Almaz-1, ERS-1/2, JERS-1, and RADARSAT satellites support the well-known fact that oceanic eddies are distributed worldwide in the ocean. The paper is devoted to an evaluation of the potential of SAR for detection of eddies and vortical motions in the ocean. The classification of typical vortical features in the ocean detected in remote sensing images (visible, infrared, and SAR) is presented as well as available information on their spatial and temporal scales. Examples of the Almaz-1 and ERS-1/2 SAR images showing different eddy types, such as rings, spiral eddies of the open ocean, eddies behind islands and in bays, spin-off eddies and mushroom-like structures (vortex dipoles) are given and discussed. It is shown that a common feature for most of the eddies detected in the SAR images is a broad spectrum of spatial scales, spiral shape and shear nature. It is concluded that the spaceborne SARs give valuable information on ocean eddies, especially in combination with visible and infrared satellite data.

  1. Soft tissue mixed tumor

    OpenAIRE

    Eiichi Hiraishi; Hiroshi Sakihara; Michiro Susa; Takayuki Honma; Hiroshi Shimosawa

    2009-01-01

    Mixed tumors are relatively common in the skin and salivary glands, but extremely rare in soft tissues, often resulting in diagnostic problems. The occurrence of these tumors in the hand is especially limited. In this article we report the clinical, radiological, and histological features of a mixed tumor of the hypothenar region of the right hand.

  2. Soft Tissue Extramedullary Plasmacytoma

    OpenAIRE

    Fernando Ruiz Santiago; Manuel Tello Moreno; Aurelio Martín Castro; Luis Guzmán Álvarez; Pedro Navarrete González

    2010-01-01

    We present the uncommon case of a subcutaneous fascia-based extramedullary plasmacytoma in the leg, which was confirmed by the pathology report and followed up until its remission. We report the differential diagnosis with other more common soft tissue masses. Imaging findings are nonspecific but are important to determine the tumour extension and to plan the biopsy.

  3. On Soft Biometrics

    DEFF Research Database (Denmark)

    Nixon, Mark; Correia, Paulo; Nasrollahi, Kamal;

    2015-01-01

    Innovation has formed much of the rich history in biometrics. The field of soft biometrics was originally aimed to augment the recognition process by fusion of metrics that were sufficient to discriminate populations rather than individuals. This was later refined to use measures that could be used...

  4. Soft Matter Characterization

    CERN Document Server

    Borsali, Redouane

    2008-01-01

    Progress in basic soft matter research is driven largely by the experimental techniques available. Much of the work is concerned with understanding them at the microscopic level, especially at the nanometer length scales that give soft matter studies a wide overlap with nanotechnology. This 2 volume reference work, split into 4 parts, presents detailed discussions of many of the major techniques commonly used as well as some of those in current development for studying and manipulating soft matter. The articles are intended to be accessible to the interdisciplinary audience (at the graduate student level and above) that is or will be engaged in soft matter studies or those in other disciplines who wish to view some of the research methods in this fascinating field. Part 1 contains articles with a largely (but, in most cases, not exclusively) theoretical content and/or that cover material relevant to more than one of the techniques covered in subsequent volumes. It includes an introductory chapter on some of t...

  5. Soft Tissue Extramedullary Plasmacytoma

    Directory of Open Access Journals (Sweden)

    Fernando Ruiz Santiago

    2010-01-01

    Full Text Available We present the uncommon case of a subcutaneous fascia-based extramedullary plasmacytoma in the leg, which was confirmed by the pathology report and followed up until its remission. We report the differential diagnosis with other more common soft tissue masses. Imaging findings are nonspecific but are important to determine the tumour extension and to plan the biopsy.

  6. Soft matrices on soft multisets in an optimal decision process

    Science.gov (United States)

    Coskun, Arzu Erdem; Aras, Cigdem Gunduz; Cakalli, Huseyin; Sonmez, Ayse

    2016-08-01

    In this paper, we introduce a concept of a soft matrix on a soft multiset, and investigate how to use soft matrices to solve decision making problems. An algorithm for a multiple choose selection problem is also provided. Finally, we demonstrate an illustrative example to show the decision making steps.

  7. Technical Development of Profile Measurement for the Soft X-Ray Via Compton Backward Scattering

    CERN Document Server

    Saito, Taku; Hayano, Hitoshi; Hidume, Kentaro; Kashiwagi, Shigeru; Kuroda, Ryunosuke; Minamiguchi, Shuichi; Oshima, Akihiro; Ueyama, Daisuke; Urakawa, Junji; Washio, Masakazu

    2005-01-01

    A compact X-ray source is called for such various fields as material development, biological science, and medical treatment. At Waseda University, we have already succeeded to generate the soft X-ray of the wavelength within so-called water window region (250-500eV) via Compton backward scattering between 1047nm Nd:YLF laser and 4.2MeV high quality electron beam. Although this method equips some useful characters, e.g. high intensity, short pulse, energy variableness, etc, the X-ray generating system is compact enough to fit in tabletop size. In the next step, there rises two principal tasks, that is, to make the soft X-ray intensity higher, and to progress X-ray profile measurement techniques as preliminary experiments for biomicroscopy. Specifically, we utilize two-pass amp for the former, and irradiate X-ray to a resist film which is previously exposed by UV lamp or get images with X-ray CCD for the latter. In this conference, we will show the experimental results and some future plans.

  8. Chemotherapy for Soft Tissue Sarcomas

    Science.gov (United States)

    ... Next Topic Targeted therapy for soft tissue sarcoma Chemotherapy for soft tissue sarcomas Chemotherapy (chemo) is the use of drugs given into ... Depending on the type and stage of sarcoma, chemotherapy may be given as the main treatment or ...

  9. Coherent processing for ISAR imaging with sparse apertures

    Institute of Scientific and Technical Information of China (English)

    SHENG JiaLian; ZHANG Lei; XU Gang; XING MengDao; BAO Zheng

    2012-01-01

    To implement target detection,tracking and imaging in a multifunctional radar system,the wideband measurements for inverse synthetic aperture radar (ISAR) imaging are usually sparsely recorded.Considering the incoherence problem in such sparse-aperture ISAR (SA-ISAR) systems,we concentrate on the study of a coherent processing method in this work.Based on an all-pole model,the incoherence parameters between abutting sub-apertures can be effectively estimated.After coherence compensation,an optimization-based SA-ISAR imaging approach is provided from the view of statistics.Simulation and real data experiments validate the feasibility and effectiveness of the proposals.

  10. Soft skills and dental education

    OpenAIRE

    Gonzalez, M. A. G.; Abu Kasim, N. H.; Naimie, Z.

    2014-01-01

    Soft skills and hard skills are essential in the practice of dentistry. While hard skills deal with technical proficiency, soft skills relate to a personal values and interpersonal skills that determine a person's ability to fit in a particular situation. These skills contribute to the success of organisations that deal face-to-face with clients. Effective soft skills benefit the dental practice. However, the teaching of soft skills remains a challenge to dental schools. This paper discus...

  11. SOFT X-RAY IMAGES OF THE SOLAR CORONA USING NORMAL INCIDENCE OPTICS

    OpenAIRE

    Bruner, M.; Haisch, B.; Brown, W.; Acton, L.; Underwood, J.

    1988-01-01

    A solar coronal loop system has been photographed in soft X-rays using a normal incidence telescope based on multilayer mirror technology. The telescope consisted of a spherical objective rnirror of 4 cm aperture and 1 m focal length, a film cassette, and a focal plane shutter. A metallized thin plastic film filter was used to exclude visible light. The objective mirror was covered with a multilayer coating consisting of alternating layers of tungsten and carbon whose combined thicknesses sat...

  12. Teaching Soft Skills Employers Need

    Science.gov (United States)

    Ellis, Maureen; Kisling, Eric; Hackworth, Robbie G.

    2014-01-01

    This study identifies the soft skills community colleges teach in an office technology course and determines whether the skills taught are congruent with the soft skills employers require in today's entry-level office work. A qualitative content analysis of a community college office technology soft skills course was performed using 23 soft…

  13. Optical Transmission Properties of Dielectric Aperture Arrays

    Science.gov (United States)

    Yang, Tao

    Optical detection devices such as optical biosensors and optical spectrometers are widely used in many applications for the functions of measurements, inspections and analysis. Due to the large dimension of prisms and gratings, the traditional optical devices normally occupy a large space with complicated components. Since cheaper and smaller optical devices are always in demand, miniaturization has been kept going for years. Thanks to recent fabrication advances, nanophotonic devices such as semiconductor laser chips have been growing in number and diversity. However, the optical biosensor chips and the optical spectrometer chips are seldom reported in the literature. For the reason of improving system integration, the study of ultra-compact, low-cost, high-performance and easy-alignment optical biosensors and optical spectrometers are imperative. This thesis is an endeavor in these two subjects and will present our research work on studying the optical transmission properties of dielectric aperture arrays and developing new optical biosensors and optical spectrometers. The first half of the thesis demonstrates that the optical phase shift associated with the surface plasmon (SP) assisted extraordinary optical transmission (EOT) in nano-hole arrays fabricated in a metal film has a strong dependence on the material refractive index value in close proximity to the holes. A novel refractive index sensor based on detecting the EOT phase shift is proposed by building a model. This device readily provides a 2-D biosensor array platform for non-labeled real-time detection of a variety of organic and biological molecules in a sensor chip format, which leads to a high packing density, minimal analyte volumes, and a large number of parallel channels while facilitating high resolution imaging and supporting a large space-bandwidth product (SBP). Simulation (FDTD Solutions, Lumerical Solutions Inc) results indicate an achievable sensitivity limit of 4.37x10-9 refractive index

  14. RADARSAT-1 synthetic aperture radar analysis

    International Nuclear Information System (INIS)

    The M/V Selendang Ayu grounded off Unalaska Island in Alaska on December 8, 2004, and spilled over 1270 m3 of oil and an unknown quantity of soybeans. The freighter grounded nearshore in a high-wave energy zone along a remote and rugged coastline, a terrain which can cause difficulties for remote sensors in detecting oil slicks. In addition, guano, kelp beds, whale and fish sperm, and releases from fishing activities generated biogenic films on the sea surface that had a signature similar to that of petroleum films. RADARSAT-1 synthetic aperture radar (SAR) imagery was used as part of the response effort to assist in the pollution monitoring effort. This paper described the methodology and results of the RADARSAT-1 analysis. Detailed information on the spill response was reported daily, and provided an opportunity to compare field observations with RADARSAT-1 SAR imagery. Observers recorded observations onto electronic maps during 35 aerial surveillance flights. Fifty-seven incident reports describing the vessel status were also used for comparison. Using screening criteria for the favorable wind and wave conditions, 37 images were available for viewing the wreck, and 22 images were acceptable for oil slick viewing. Image analysis for the wreck suggested that the sensor has the resolution and capability to monitor a grounded freighter. Visual inspection of the images showed that SAR can capture changes in vessel status, such as the gradual sinking of the bow. However, SAR's oil slick detection capability was disappointing due to the significant number of biogenic films in the nearshore areas of Alaska. It was concluded that future work should concentrate on developing a ranking system to indicate analysis confidence that a particular image does in fact contain a petroleum pocket. 25 refs., 2 tabs., 10 figs

  15. Morphometric analysis of septal aperture of humerus

    Directory of Open Access Journals (Sweden)

    Raghavendra K, Anil kumar Reddy Y, Shirol VS, Daksha Dixit, Desai SP

    2014-04-01

    Full Text Available Introduction: Lower end of humerus shows olecranon and coronoid fossae separated by a thin bony septum, sometimes it may deficient and shows foramen which communicates both the fossae called Septal aperture, which is commonly referred as supratrochlear foramen (STF. Materials & Methods: We have studied 260 humeri (126 right side and 134 left side, measurements were taken by using vernier caliper, translucency septum was observed by keeping the lower end of humerus against the x-ray lobby. Results: A clear cut STF was observed in 19.2% bones, translucency septum was observed in 99 (91.6% humeri on the right side and 95 (93.1% humeri on the left sides respectively (Table – 1. Clinical significance: The presence of STF is always associated with the narrow medullary canal at the lower end of humerus, Supracondylar fracture of humerus is most common in paediatric age group, medullary nailing is done to treat the fractures in those cases the knowledge about the STF is very important for treating the fractures. It has been observed in x-ray of lower end of the humerus the STF is comparatively radiolucent, it is commonly seen as a type of ‘pseudolesions’ in an x-ray of the lower end of humerus and it may mistake for an osteolytic or cystic lesions. Conclusion: The present study can add data into anthropology and anatomy text books regarding STF and it gives knowledge of understanding anatomical variation of distal end of the humerus, which is significant for anthropologists, orthopaedic surgeons and radiologists in habitual clinical practice.

  16. Triangulation using synthetic aperture radar images

    Science.gov (United States)

    Wu, Sherman S. C.; Howington-Kraus, Annie E.

    1991-01-01

    For the extraction of topographic information about Venus from stereoradar images obtained from the Magellan Mission, a Synthetic Aperture Radar (SAR) compilation system was developed on analytical stereoplotters. The system software was extensively tested by using stereoradar images from various spacecraft and airborne radar systems, including Seasat, SIR-B, ERIM XCL, and STAR-1. Stereomodeling from radar images was proven feasible, and development is on a correct approach. During testing, the software was enhanced and modified to obtain more flexibility and better precision. Triangulation software for establishing control points by using SAR images was also developed through a joint effort with the Defense Mapping Agency. The SAR triangulation system comprises four main programs, TRIDATA, MODDATA, TRISAR, and SHEAR. The first two programs are used to sort and update the data; the third program, the main one, performs iterative statistical adjustment; and the fourth program analyzes the results. Also, input are flight data and data from the Global Positioning System and Inertial System (navigation information). The SAR triangulation system was tested with six strips of STAR-1 radar images on a VAX-750 computer. Each strip contains images of 10 minutes flight time (equivalent to a ground distance of 73.5 km); the images cover a ground width of 22.5 km. All images were collected from the same side. With an input of 44 primary control points, 441 ground control points were produced. The adjustment process converged after eight iterations. With a 6-m/pixel resolution of the radar images, the triangulation adjustment has an average standard elevation error of 81 m. Development of Magellan radargrammetry will be continued to convert both SAR compilation and triangulation systems into digital form.

  17. The LASS [Larger Aperture Superconducting Solenoid] spectrometer

    International Nuclear Information System (INIS)

    LASS is the acronym for the Large Aperture Superconducting Solenoid spectrometer which is located in an rf-separated hadron beam at the Stanford Linear Accelerator Center. This spectrometer was constructed in order to perform high statistics studies of multiparticle final states produced in hadron reactions. Such reactions are frequently characterized by events having complicated topologies and/or relatively high particle multiplicity. Their detailed study requires a spectrometer which can provide good resolution in momentum and position over almost the entire solid angle subtended by the production point. In addition, good final state particle identification must be available so that separation of the many kinematically-overlapping final states can be achieved. Precise analyses of the individual reaction channels require high statistics, so that the spectrometer must be capable of high data-taking rates in order that such samples can be acquired in a reasonable running time. Finally, the spectrometer must be complemented by a sophisticated off-line analysis package which efficiently finds tracks, recognizes and fits event topologies and correctly associates the available particle identification information. This, together with complicated programs which perform specific analysis tasks such as partial wave analysis, requires a great deal of software effort allied to a very large computing capacity. This paper describes the construction and performance of the LASS spectrometer, which is an attempt to realize the features just discussed. The configuration of the spectrometer corresponds to the data-taking on K+ and K- interactions in hydrogen at 11 GeV/c which took place in 1981 and 1982. This constitutes a major upgrade of the configuration used to acquire lower statistics data on 11 GeV/c K-p interactions during 1977 and 1978, which is also described briefly

  18. RADARSAT-1 synthetic aperture radar analysis

    Energy Technology Data Exchange (ETDEWEB)

    Simecek-Beatty, D. [National Oceanic and Atmospheric Adminstration, National Ocean Service, Seattle, WA (United States). Office of Response and Restoration; Pichel, W.G. [National Oceanic and Atmospheric Administration, National Environmental Satellite, Data and Information Service, Camp Springs, MD (United States). Office of Research and Applications

    2006-07-01

    The M/V Selendang Ayu grounded off Unalaska Island in Alaska on December 8, 2004, and spilled over 1270 m{sup 3} of oil and an unknown quantity of soybeans. The freighter grounded nearshore in a high-wave energy zone along a remote and rugged coastline, a terrain which can cause difficulties for remote sensors in detecting oil slicks. In addition, guano, kelp beds, whale and fish sperm, and releases from fishing activities generated biogenic films on the sea surface that had a signature similar to that of petroleum films. RADARSAT-1 synthetic aperture radar (SAR) imagery was used as part of the response effort to assist in the pollution monitoring effort. This paper described the methodology and results of the RADARSAT-1 analysis. Detailed information on the spill response was reported daily, and provided an opportunity to compare field observations with RADARSAT-1 SAR imagery. Observers recorded observations onto electronic maps during 35 aerial surveillance flights. Fifty-seven incident reports describing the vessel status were also used for comparison. Using screening criteria for the favorable wind and wave conditions, 37 images were available for viewing the wreck, and 22 images were acceptable for oil slick viewing. Image analysis for the wreck suggested that the sensor has the resolution and capability to monitor a grounded freighter. Visual inspection of the images showed that SAR can capture changes in vessel status, such as the gradual sinking of the bow. However, SAR's oil slick detection capability was disappointing due to the significant number of biogenic films in the nearshore areas of Alaska. It was concluded that future work should concentrate on developing a ranking system to indicate analysis confidence that a particular image does in fact contain a petroleum pocket. 25 refs., 2 tabs., 10 figs.

  19. Detection of small, slow ground targets using Synthetic Aperture Radar

    Science.gov (United States)

    Chen, Curtis; Chapin, Elaine; Rosen, Paul

    2005-01-01

    Synthetic aperture radar (SAR) along-track interferometry (ATI) is a technique for sensing Earth-surface motion. The technique involves interferometrically combining data from two radar images acquired from phase centers separated along the platform flight track.

  20. Synthetic aperture radar signal processing: Trends and technologies

    Science.gov (United States)

    Curlander, John C.

    1993-01-01

    An overview of synthetic aperture radar (SAR) technology is presented in vugraph form. The following topics are covered: an SAR ground data system; SAR signal processing algorithms; SAR correlator architectures; and current and future trends.

  1. Stellwagen Bank National Marine Sanctuary - Synthetic Aperture Radar (SAR) Imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geodatabase contains Synthetic Aperture Radar images (SAR), which consist of a fine resolution (12.5-50m), two-dimensional radar backscatter map of the...

  2. An Adaptive Homomorphic Aperture Photometry Algorithm for Merging Galaxies

    CERN Document Server

    Huang, Jen-Chao

    2016-01-01

    We present a novel automatic adaptive aperture photometry algorithm for measuring the total magnitudes of merging galaxies with irregular shapes. First, we use a morphological pattern recognition routine for identifying the shape of an irregular source in a background-subtracted image. Then, we extend the shape of the source by using the Dilation image operation to obtain an aperture that is quasi-homomorphic to the shape of the irregular source. The magnitude measured from the homomorphic aperture would thus have minimal contamination from the nearby background. As a test of our algorithm, we applied our technique to the merging galaxies observed by the Sloan Digital Sky Survey (SDSS) and the Canada-France-Hawaii Telescope (CFHT). Our results suggest that the adaptive homomorphic aperture algorithm can be very useful for investigating extended sources with irregular shapes and sources in crowded regions.

  3. Ultra-Lightweight Large Aperture Support Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Ultra-lightweight membranes may prove to be very attractive for large aperture systems, but their value will be fully realized only if they are mated with equally...

  4. Aperture Arrays for the SKA: Dense or Sparse?

    CERN Document Server

    Braun, R; Braun, Robert; Cappellen, Wim van

    2006-01-01

    We briefly consider some design aspects of aperture arrays for use in radio astronomy, particularly contrasting the performance of dense and sparse aperture arrays. Recent insights have emerged in the final design phase of LOFAR which suggest that sparse aperture arrays have the best prospects for cost-effective performance at radio frequencies below about 500 MHz; exceeding those of both dense aperture arrays and parabolic reflectors by an order of magnitude. Very attractive performance, of 10,000 - 20,000 m2/K, can be achieved with a sparse design that covers the 70 - 700 MHz range with two antenna systems that share receiver resources. Cost-effective systems of this type represent only a modest increment in system complexity over that being deployed in LOFAR and are achievable with today's technology.

  5. Effect of bandwidth and numerical aperture in optical scatterometry

    Science.gov (United States)

    Germer, Thomas A.; Patrick, Heather J.

    2010-03-01

    We consider the effects of finite spectral bandwidth and numerical aperture in scatterometry measurements and discuss efficient integration methods based upon Gaussian quadrature in one dimension (for spectral bandwidth averaging) and two dimensions inside a circle (for numerical aperture averaging). Provided the wavelength is not near a Wood's anomaly for the grating, we find that the resulting methods converge very quickly to a level suitable for most measurement applications. In the vicinity of a Wood's anomaly, however, the methods provide rather poor behavior. We also describe a method that can be used to extract the effective spectral bandwidth and numerical aperture for a scatterometry tool. We find that accounting for spectral bandwidth and numerical aperture is necessary to obtain satisfactory results in scatterometry.

  6. Foamed Antenna Support for Very Large Apertures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Large aperture antennas are of interest to NASA for applications in establishing high-speed communication relays for interplanetary missions. Design goals include...

  7. Photonic spin-controlled multifunctional shared-aperture antenna array

    Science.gov (United States)

    Maguid, Elhanan; Yulevich, Igor; Veksler, Dekel; Kleiner, Vladimir; Brongersma, Mark L.; Hasman, Erez

    2016-06-01

    The shared-aperture phased antenna array developed in the field of radar applications is a promising approach for increased functionality in photonics. The alliance between the shared-aperture concepts and the geometric phase phenomenon arising from spin-orbit interaction provides a route to implement photonic spin-control multifunctional metasurfaces. We adopted a thinning technique within the shared-aperture synthesis and investigated interleaved sparse nanoantenna matrices and the spin-enabled asymmetric harmonic response to achieve helicity-controlled multiple structured wavefronts such as vortex beams carrying orbital angular momentum. We used multiplexed geometric phase profiles to simultaneously measure spectrum characteristics and the polarization state of light, enabling integrated on-chip spectropolarimetric analysis. The shared-aperture metasurface platform opens a pathway to novel types of nanophotonic functionality.

  8. Stitching interferometry for cylindrical optics with large angular aperture

    International Nuclear Information System (INIS)

    Stitching interferometry is an attractive method for measuring optics with large apertures. However, existing stitching algorithms are not suitable for measuring cylindrical optics, because the misalignment aberrations in cylindrical interferometry are more complicated than those in plane, spherical and aspherical measurements. This paper presents a stitching algorithm for measuring cylindrical optics with large angular apertures. With it, we use five aberrations (i.e. piston, tilt, tip, defocus and twist) to describe the possible misalignments of the tested cylindrical surface and to build the cylindrical stitching model. Using this model allows us to calculate the relative misalignment aberrations of subapertures from their overlapped areas, so that the full aperture map of a cylindrical surface is obtained by compensating for these misalignment aberrations. In experiment, a cylindrical lens with an angular aperture over 150° is measured, thus demonstrating the feasibility and validity of the proposed method. (paper)

  9. Foamed Antenna Support for Very Large Apertures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase I program will demonstrate the feasibility of the in-space production of large aperture antenna structures. The use of a novel open cell foam,...

  10. Electronic aperture control devised for solid state imaging system

    Science.gov (United States)

    Anders, R. A.; Callahan, D. E.; Mc Cann, D. H.

    1968-01-01

    Electronic means of performing the equivalent of automatic aperture control has been devised for the new class of television cameras that incorporates a solid state imaging device in the form of phototransistor mosaic sensors.

  11. Autofocus algorithm for synthetic aperture radar imaging with large curvilinear apertures

    International Nuclear Information System (INIS)

    An approach to autofocusing for large curved synthetic aperture radar (SAR) apertures is presented. Its essential feature is that phase corrections are being extracted not directly from SAR images, but rather from reconstructed SAR phase-history data representing windowed patches of the scene, of sizes sufficiently small to allow the linearization of the forward- and back-projection formulae. The algorithm processes data associated with each patch independently and in two steps. The first step employs a phase-gradient-type method in which phase correction compensating (possibly rapid) trajectory perturbations are estimated from the reconstructed phase history for the dominant scattering point on the patch. The second step uses phase-gradient-corrected data and extracts the absolute phase value, removing in this way phase ambiguities and reducing possible imperfections of the first stage, and providing the distances between the sensor and the scattering point with accuracy comparable to the wavelength. The features of the proposed autofocusing method are illustrated in its applications to intentionally corrupted small-scene 2006 Gotcha data. The examples include the extraction of absolute phases (ranges) for selected prominent point targets. They are then used to focus the scene and determine relative target–target distances. (paper)

  12. Shallow Water Height Mapping With Interferometric Synthetic Aperture Sonar

    OpenAIRE

    Sergio Rui Silva; Sergio Cunha; Anibal Matos; Nuno Cruz

    2008-01-01

    Height mapping of shallow water areas is an important task for many commercial and scientific applications like river navigability, infrastructure maintenance or natural resource monitoring. The use of an autonomous boat presents several advantages that case the use of synthetic aperture images to create three-dimensional topographic maps through interferometric techniques. Sample data obtained during test trials illustrate how synthetic aperture can be used to generate imagery and bathymetry...

  13. Synthetic aperture single-exposure on-axis digital holography

    OpenAIRE

    Martínez León, Lluís; Javidi, Bahram

    2008-01-01

    We present a system for reconstructing single-exposure on-line (SEOL) digital holograms with improved resolution using a synthetic aperture. Several recordings are made in order to compose the synthetic aperture, shifting the camera within the hologram plane. After processing the synthetic hologram, an inverse Fresnel transformation provides an enhanced resolution reconstruction. We show that recognition capacity for high frequency details is increased. Experimental results ...

  14. Radiometric resolution of motion-induced synthetic aperture radiometer

    OpenAIRE

    Hyuk, Park; Camps Carmona, Adriano José; Choi, Min Gyu; Kim, Yong-Hoon

    2011-01-01

    The radiometric resolution of a motion-induced synthetic aperture radiometer (MISAR) is analytically obtained from the standard deviation of a baseline response, an observation scenario, and the imaging method of the MISAR. The intrinsic long integration time given by the whole dwell time on moving platforms improves the radiometric resolution compared with the snapshot resolution of other nominal synthetic aperture radiometers. In addition, it is illustrated that the MISAR imaging hold...

  15. The synthetic aperture method in the environment microwave interferometer radiometry

    OpenAIRE

    Kutuza, B.G.; Zagorin, G. K.

    2003-01-01

    The basic principles of space-borne two dimensional synthetic aperture microwave polarimetric interferometer function are considered. The main advantages of these systems over the well-known systems ESMR, SMMR and SSM/I are: a high rate of the observation scene image construction; the finite angular resolution; besides, they have no movable onboard construction elements on the spacecraft board, like the scanning antenna, and etc. The advantages of the synthetic aperture systems with hexagonal...

  16. Transmission of High-Power Electron Beams Through Small Apertures

    CERN Document Server

    Tschalär, C; Balascuta, S.; Benson, S.V.; Bertozzi, W.; Boyce, J.R.; Cowan, R.; Douglas, D.; Evtushenko, P.; Fisher, P.; Ihloff, E.; Kalantarians, N.; Kelleher, A.; Legg, R.; Milner, R.G.; Neil, G.R.; Ou, L.; Schmookler, B.; Tennant, C.; Williams, G.P.; Zhang, S.

    2013-01-01

    Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 hour continuous run.

  17. Dynamic Aperture Of The Heavy Ion Collider Nica

    International Nuclear Information System (INIS)

    Dynamic aperture of the heavy ion collider NICA which is under construction at the Joint Institute for Nuclear Research in Dubna has been studied. Both nonlinearities in the magnetic elements and beam-beam forces have been taken into account in the numerical simulations. The obtained values of the dynamic aperture and the nonlinear acceptance are close to those in other heavy ion accelerators. Key words: particle accelerators, collider, beam dynamics

  18. Soft-Collinear Supersymmetry

    CERN Document Server

    Cohen, Timothy; Larkoski, Andrew J

    2016-01-01

    Soft-Collinear Effective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. This paper demonstrates that SCET can be made compatible with supersymmetry (SUSY). Explicitly, the effective theory for $\\mathcal{N} = 1$ SUSY Yang-Mills is constructed and shown to be consistent. For contrast, arguments are given that chiral SUSY theories with Yukawa couplings, specifically the single flavor Wess-Zumino model, are incompatible with the collinear expansion. SCET is formulated by expanding fields along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light-cone. Defining the theory with respect to a specific frame obfuscates Lorentz invariance -- given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms: collinear fermions a...

  19. Genital soft tissue tumors.

    Science.gov (United States)

    Schoolmeester, John K; Fritchie, Karen J

    2015-07-01

    Mesenchymal neoplasms of the vulvovaginal and inguinoscrotal regions are among the most diagnostically challenging specimens in the pathology laboratory owing largely to their unique intersection between general soft tissue tumors and relatively genital-specific mesenchymal tumors. Genital stromal tumors are a unique subset of soft tissue tumors encountered at this location, and this group includes fibroepithelial stromal polyp, superficial (cervicovaginal) myofibroblastoma, cellular angiofibroma, mammary-type myofibroblastoma, angiomyofibroblastoma and aggressive angiomyxoma. Aside from the striking morphologic and immunophenotypic similarity that is seen with these entities, there is evidence that a subset of genital stromal tumors may be linked genetically. This review will focus on simplifying this group of tumors and provide the pathologist or dermatopathologist with practical management information. Smooth muscle tumors of the external genitalia will also be discussed.

  20. Biological Soft Robotics.

    Science.gov (United States)

    Feinberg, Adam W

    2015-01-01

    In nature, nanometer-scale molecular motors are used to generate force within cells for diverse processes from transcription and transport to muscle contraction. This adaptability and scalability across wide temporal, spatial, and force regimes have spurred the development of biological soft robotic systems that seek to mimic and extend these capabilities. This review describes how molecular motors are hierarchically organized into larger-scale structures in order to provide a basic understanding of how these systems work in nature and the complexity and functionality we hope to replicate in biological soft robotics. These span the subcellular scale to macroscale, and this article focuses on the integration of biological components with synthetic materials, coupled with bioinspired robotic design. Key examples include nanoscale molecular motor-powered actuators, microscale bacteria-controlled devices, and macroscale muscle-powered robots that grasp, walk, and swim. Finally, the current challenges and future opportunities in the field are addressed.

  1. Facial soft tissue segmentation

    OpenAIRE

    Majeed, Tahir

    2014-01-01

    The importance of the face for socio-ecological interaction is the cause for a high demand on any surgical intervention on the facial musculo-skeletal system. Bones and soft-tissues are of major importance for any facial surgical treatment to guarantee an optimal, functional and aesthetical result. For this reason, surgeons want to pre-operatively plan, simulate and predict the outcome of the surgery allowing for shorter operation times and improved quality. Accurate simulation requires exact...

  2. Neonatal soft tissue tumours.

    OpenAIRE

    Spicer, R D

    1992-01-01

    Thirty-five different soft tissue tumours occurring in the first month of life are described and classified into five Clinical Groups. A. Excellent prognosis with no treatment or simple surgical excision. B. Good prognosis. Treatment depends upon anatomical site. C. Good prognosis. Treatment usually surgical but chemotherapy may be indicated in certain situations. D. Intermediate prognosis. Treatment as for older child, usually surgery or chemotherapy. E. Poor prognosis. Treatment palliative ...

  3. Myoepithelioma of soft tissue

    OpenAIRE

    Pai Mukhta; Naik Ramadas; Kamath Ramachandra; Magar Dilasma

    2009-01-01

    Myoepitheliomas and mixed tumors involving deep subcutaneous and subfascial soft tissues of limb or limb girdle are rare lesions as against salivary lesions that are well established conditions. Here, we report a 22-year-old female who presented with painful hard swelling in the left gluteal region of 1½ year duration. MRI showed a large ill-defined heterogeneous mass lesion measuring about 7-8 cm. in the left sacral region eroding the left sacroiliac region and left sacroiliac joint. ...

  4. Soft tissue case 61

    OpenAIRE

    Aird, Lisa; Tiwari, Pari; Brown, Carl J.

    2009-01-01

    A 55-year-old man presented to the emergency department with a 12-hour history of severe crampy abdominal pain, nausea, vomiting and obstipation. The patient had a complex medical history, including coronary artery disease, lupus, hypothyroidism, epilepsy, pancreatitis and renal calculi. However, the patient had no history of a hernia or abdominal surgery. Physical examination revealed a temperature of 38.5°C and a soft distended abdomen that was diffusely tender without signs of peritonitis....

  5. Soft tissue myoepithelial carcinoma

    OpenAIRE

    Stojšić Zorica; Brašanac Dimitrije; Bacetić Dragoljub; Janković Radmila; Drndarević Neda

    2006-01-01

    Background. Myoepitheliomas are tumors composed predominantly or exclusively of myoepithelial cells, usually arising in salivary glands. Cutaneous/soft tissue localization is very rare, especially for the malignant myoepitheliomas. Case report. We presented a case of myoepithelial carcinoma involving subcutaneous adipose tissue of the left forearm in a woman aged 62 years. The tumor was composed of epithelioid and hyaline cell types, arranged in diffuse sheets, nests and loose clusters within...

  6. Necrotizing soft tissue infections

    OpenAIRE

    Holtom, P D

    1999-01-01

    Necrotizing soft tissue infections are a group of highly lethal infections that typically occur after trauma or surgery. Many individual infectious entities have been described, but they all have similar pathophysiologies, clinical features, and treatment approaches. The essentials of successful treatment include early diagnosis, aggressive surgical debridement, antibiotics, and supportive intensive treatment unit care. The two commonest pitfalls in management are failure of early diagnosis a...

  7. Soft tissue injections

    OpenAIRE

    Inês, Luís P. B. S.; Silva, José António P. da

    2005-01-01

    Soft tissue rheumatism includes a wide spectrum of common lesions of the tendons, enthesis, tendon sheaths, bursae, ligaments and fasciae as well as nerve compression syndromes. Studies on the pathogenesis of these lesions do not support a major role for inflammation, thus questioning the rationale for glucocorticoid injections. This chapter reviews current indications for local glucocorticoid injections and available evidence on its efficacy, as well as contraindications and potential risks....

  8. Electrostatics in soft matter

    OpenAIRE

    Messina, Rene

    2008-01-01

    Recent progress in the understanding of the effect of electrostatics in soft matter is presented. A vast amount of materials contains ions ranging from the molecular scale (e.g., electrolyte) to the meso/macroscopic one (e.g., charged colloidal particles or polyelectrolytes). Their (micro)structure and physicochemical properties are especially dictated by the famous and redoubtable long-ranged Coulomb interaction. In particular theoretical and simulational aspects, including the experimental ...

  9. Soft interactions in Herwig++

    CERN Document Server

    Bahr, Manuel; Gieseke, Stefan; Seymour, Michael H

    2009-01-01

    We describe the recent developments to extend the multi-parton interaction model of underlying events in Herwig++ into the soft, non-perturbative, regime. This allows the program to describe also minimum bias collisions in which there is no hard interaction, for the first time. It is publicly available from versions 2.3 onwards and describes the Tevatron underlying event and minimum bias data. The extrapolations to the LHC nevertheless suffer considerable ambiguity, as we discuss.

  10. Some Results on Fuzzy Soft Topological Spaces

    OpenAIRE

    Cigdem Gunduz (Aras); Sadi Bayramov

    2013-01-01

    We introduce some important properties of fuzzy soft topological spaces. Furthermore, fuzzy soft continuous mapping, fuzzy soft open and fuzzy soft closed mappings, and fuzzy soft homeomorphism for fuzzy soft topological spaces are given and structural characteristics are discussed and studied.

  11. Transport of Particle Swarms Through Variable Aperture Fractures

    Science.gov (United States)

    Boomsma, E.; Pyrak-Nolte, L. J.

    2012-12-01

    Particle transport through fractured rock is a key concern with the increased use of micro- and nano-size particles in consumer products as well as from other activities in the sub- and near surface (e.g. mining, industrial waste, hydraulic fracturing, etc.). While particle transport is often studied as the transport of emulsions or dispersions, particles may also enter the subsurface from leaks or seepage that lead to particle swarms. Swarms are drop-like collections of millions of colloidal-sized particles that exhibit a number of unique characteristics when compared to dispersions and emulsions. Any contaminant or engineered particle that forms a swarm can be transported farther, faster, and more cohesively in fractures than would be expected from a traditional dispersion model. In this study, the effects of several variable aperture fractures on colloidal swarm cohesiveness and evolution were studied as a swarm fell under gravity and interacted with the fracture walls. Transparent acrylic was used to fabricate synthetic fracture samples with (1) a uniform aperture, (2) a converging region followed by a uniform region (funnel shaped), (3) a uniform region followed by a diverging region (inverted funnel), and (4) a cast of a an induced fracture from a carbonate rock. All of the samples consisted of two blocks that measured 100 x 100 x 50 mm. The minimum separation between these blocks determined the nominal aperture (0.5 mm to 20 mm). During experiments a fracture was fully submerged in water and swarms were released into it. The swarms consisted of a dilute suspension of 3 micron polystyrene fluorescent beads (1% by mass) with an initial volume of 5μL. The swarms were illuminated with a green (525 nm) LED array and imaged optically with a CCD camera. The variation in fracture aperture controlled swarm behavior. Diverging apertures caused a sudden loss of confinement that resulted in a rapid change in the swarm's shape as well as a sharp increase in its velocity

  12. Propagation-based phase-contrast enhancement of nanostructure images using a debris-free femtosecond-laser-driven cluster-based plasma soft x-ray source and an LiF crystal detector

    International Nuclear Information System (INIS)

    We demonstrate in-line phase-contrast imaging of nanothickness foils by using a relatively large, polychromatic, debris-free femtosecond-laser-driven cluster-based plasma soft x-ray source, and a high-resolution, large dynamic range LiF crystal detector. The spatial coherence length of radiation in our setup reached a value of 5 μm on the sample plane, which is enough to observe phase-contrast enhancement in the images registered by the detector placed only a few hundred micrometers behind the object. We have developed a tabletop soft x-ray emission source, which emits radiation within a 4π sr solid angle, and which allows one to obtain contact and propagation-based phase-contrast imaging of nanostructures with 700 nm spatial resolutions. This advance could be of utility for metrology applications.

  13. Programmable Aperture with MEMS Microshutter Arrays

    Science.gov (United States)

    Moseley, Samuel; Li, Mary; Kutyrev, Alexander; Kletetschka, Gunther; Fettig, Rainer

    2011-01-01

    A microshutter array (MSA) has been developed for use as an aperture array for multi-object selections in James Webb Space Telescope (JWST) technology. Light shields, molybdenum nitride (MoN) coating on shutters, and aluminum/aluminum oxide coatings on interior walls are put on each shutter for light leak prevention, and to enhance optical contrast. Individual shutters are patterned with a torsion flexure that permits shutters to open 90 deg. with a minimized mechanical stress concentration. The shutters are actuated magnetically, latched, and addressed electrostatically. Also, micromechanical features are tailored onto individual shutters to prevent stiction. An individual shutter consists of a torsion hinge, a shutter blade, a front electrode that is coated on the shutter blade, a backside electrode that is coated on the interior walls, and a magnetic cobalt-iron coating. The magnetic coating is patterned into stripes on microshutters so that shutters can respond to an external magnetic field for the magnetic actuation. A set of column electrodes is placed on top of shutters, and a set of row electrodes on sidewalls is underneath the shutters so that they can be electrostatically latched open. A linear permanent magnet is aligned with the shutter rows and is positioned above a flipped upside-down array, and sweeps across the array in a direction parallel to shutter columns. As the magnet sweeps across the array, sequential rows of shutters are rotated from their natural horizontal orientation to a vertical open position, where they approach vertical electrodes on the sidewalls. When the electrodes are biased with a sufficient electrostatic force to overcome the mechanical restoring force of torsion bars, shutters remain latched to vertical electrodes in their open state. When the bias is removed, or is insufficient, the shutters return to their horizontal, closed positions. To release a shutter, both the electrode on the shutter and the one on the back wall where

  14. Oil Slick Characterization Using Synthetic Aperture Radar

    Science.gov (United States)

    Jones, C. E.; Breivik, O.; Brekke, C.; Skrunes, S.; Holt, B.

    2015-12-01

    Oil spills are a hazard worldwide with potential of causing high impact disasters, and require an active oil spill response capability to protect personnel, the ecosystem, and the energy supply. As the amount of oil in traditionally accessible reserves decline, there will be increasing oil extraction from the Arctic and deep-water wells, both new sources with high risk and high cost for monitoring and response. Although radar has long been used for mapping the spatial extent of oil slicks, it is only since the Deepwater Horizon spill that synthetic aperture radar (SAR) has been shown capable of characterizing oil properties within a slick, and therefore useful for directing response to the recoverable thicker slicks or emulsions. Here we discuss a 2015 Norwegian oil-on-water spill experiment in which emulsions of known quantity and water-to-oil ratio along with a look-alike slick of plant oil were released in the North Sea and imaged with polarimetric SAR (PolSAR) by NASA's UAVSAR instrument for several hours following release. During the experiment, extensive in situ measurements were made from ship or aircraft with meteorological instruments, released drift buoys, and optical/IR imagers. The experiment was designed to provide validation data for development of a physical model relating polarization-dependent electromagnetic scattering to the dielectric properties of oil mixed with ocean water, which is the basis for oil characterization with SAR. Data were acquired with X-, C-, and L-band satellite-based SARs to enable multi-frequency comparison of characterization capabilities. In addition, the data are used to develop methods to differentiate mineral slicks from biogenic look-alikes, and to better understand slick weathering and dispersion. The results will provide a basis for modeling oil-in-ice spills, currently a high priority for nations involved in Arctic oil exploration. Here we discuss the Norwegian experiment, the validation data, and the results of

  15. Deployable Wide-Aperture Array Antennas

    Science.gov (United States)

    Fink, Patrick W.; Dobbins, Justin A.; Lin, Greg Y.; Chu, Andrew; Scully, Robert C.

    2005-01-01

    Inexpensive, lightweight array antennas on flexible substrates are under development to satisfy a need for large-aperture antennas that can be stored compactly during transport and deployed to full size in the field. Conceived for use aboard spacecraft, antennas of this type also have potential terrestrial uses . most likely, as means to extend the ranges of cellular telephones in rural settings. Several simple deployment mechanisms are envisioned. One example is shown in the figure, where the deployment mechanism, a springlike material contained in a sleeve around the perimeter of a flexible membrane, is based on a common automobile window shade. The array can be formed of antenna elements that are printed on small sections of semi-flexible laminates, or preferably, elements that are constructed of conducting fabric. Likewise, a distribution network connecting the elements can be created from conventional technologies such as lightweight, flexible coaxial cable and a surface mount power divider, or preferably, from elements formed from conductive fabrics. Conventional technologies may be stitched onto a supporting flexible membrane or contained within pockets that are stitched onto a flexible membrane. Components created from conductive fabrics may be attached by stitching conductive strips to a nonconductive membrane, embroidering conductive threads into a nonconductive membrane, or weaving predetermined patterns directly into the membrane. The deployable antenna may comprise multiple types of antenna elements. For example, thin profile antenna elements above a ground plane, both attached to the supporting flexible membrane, can be used to create a unidirectional boresight radiation pattern. Or, antenna elements without a ground plane, such as bow-tie dipoles, can be attached to the membrane to create a bidirectional array such as that shown in the figure. For either type of antenna element, the dual configuration, i.e., elements formed of slots in a conductive

  16. Wind energy applications of synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Bruun Christiansen, M.

    2006-11-15

    Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting wind fields are valuable in offshore wind energy planning as a supplement to on site measurements, which are costly and sparse, and model wind fields, which are not fully validated. Two applications of SAR measurements in offshore wind energy planning are addressed here: the study of wind farm wake effects and the potential of using SAR winds in offshore wind resource assessment. Firstly, wind wakes behind two large offshore wind farms in Denmark Horns Rev and Nysted are identified. A region of reduced wind speed is found downstream of both wind farms from the SAR wind fields. The wake extent and magnitude depends on the wind speed, the atmospheric stability, and the fraction of turbines operating. Wind farm wake effects are detected up to 20 km downwind of the last turbine. This distance is longer than predicted by state-of-the art wake models. Wake losses are typically 10-20% near the wind farms. Secondly, the potential of using SAR wind maps in offshore wind resource assessment is investigated. The resource assessment is made through Weibull fitting to frequency observations of wind speed and requires at least 100 satellite observations per year for a given site of interest. Predictions of the energy density are very sensitive to the wind speed and the highest possible accuracy on SAR wind retrievals is therefore sought. A 1.1 m s{sup -1} deviation on the mean wind speed is found through comparison with mast measurements at Horns Rev. The accuracy on mean wind speeds and energy densities found from satellite measurements varies with different empirical model functions. Additional uncertainties are introduced by the infrequent satellite sampling at fixed times of the day. The accuracy on satellite based wind resource

  17. Cavity-excited Huygens' metasurface antennas for near-unity aperture illumination efficiency from arbitrarily large apertures.

    Science.gov (United States)

    Epstein, Ariel; Wong, Joseph P S; Eleftheriades, George V

    2016-01-21

    One of the long-standing problems in antenna engineering is the realization of highly directive beams using low-profile devices. In this paper, we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and (equivalent) magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source-fed cavity is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectra typical to standard partially reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern, without incurring edge-taper losses. The proposed low-profile design yields near-unity aperture illumination efficiencies from arbitrarily large apertures, offering new capabilities for microwave, terahertz and optical radiators.

  18. Cavity-excited Huygens' metasurface antennas for near-unity aperture illumination efficiency from arbitrarily large apertures

    Science.gov (United States)

    Epstein, Ariel; Wong, Joseph P. S.; Eleftheriades, George V.

    2016-01-01

    One of the long-standing problems in antenna engineering is the realization of highly directive beams using low-profile devices. In this paper, we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and (equivalent) magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source-fed cavity is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectra typical to standard partially reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern, without incurring edge-taper losses. The proposed low-profile design yields near-unity aperture illumination efficiencies from arbitrarily large apertures, offering new capabilities for microwave, terahertz and optical radiators.

  19. Cavity-excited Huygens' metasurface antennas for near-unity aperture illumination efficiency from arbitrarily large apertures.

    Science.gov (United States)

    Epstein, Ariel; Wong, Joseph P S; Eleftheriades, George V

    2016-01-01

    One of the long-standing problems in antenna engineering is the realization of highly directive beams using low-profile devices. In this paper, we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and (equivalent) magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source-fed cavity is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectra typical to standard partially reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern, without incurring edge-taper losses. The proposed low-profile design yields near-unity aperture illumination efficiencies from arbitrarily large apertures, offering new capabilities for microwave, terahertz and optical radiators. PMID:26790605

  20. Experimental Investigation of an L-Shaped Very-Small-Aperture Laser

    Institute of Scientific and Technical Information of China (English)

    XU Ji-Ying; WANG Jia; GAI Hong-Feng; TIAN Qian; WANG Bo-Xiong; HAO Zhi-Biao; HAN Shuo

    2006-01-01

    @@ An L-shaped very-small-aperture laser (VSAL) with high power output and field enhancement effect is fabricated and characterized. As a comparison, a conventional rectangular VSAL and a double-aperture VSAL containing one L-aperture and one rectangular aperture are also fabricated and measured.

  1. A table-top, repetitive pulsed magnet for nonlinear and ultrafast spectroscopy in high magnetic fields up to 30 T.

    Science.gov (United States)

    Noe, G Timothy; Nojiri, Hiroyuki; Lee, Joseph; Woods, Gary L; Léotin, Jean; Kono, Junichiro

    2013-12-01

    We have developed a mini-coil pulsed magnet system with direct optical access, ideally suited for nonlinear and ultrafast spectroscopy studies of materials in high magnetic fields up to 30 T. The apparatus consists of a small coil in a liquid nitrogen cryostat coupled with a helium flow cryostat to provide sample temperatures down to below 10 K. Direct optical access to the sample is achieved with the use of easily interchangeable windows separated by a short distance of ~135 mm on either side of the coupled cryostats with numerical apertures of 0.20 and 0.03 for measurements employing the Faraday geometry. As a demonstration, we performed time-resolved and time-integrated photoluminescence measurements as well as transmission measurements on InGaAs quantum wells. PMID:24387445

  2. Highly efficient tabletop x-ray laser at λ=41.8 nm in Pd-like xenon pumped by optical-field ionization in a cluster jet

    International Nuclear Information System (INIS)

    The atomic-kinetic calculations of gain at 41.8 nm in Pd-like xenon are performed. The interpretation of known experiments has proved that x-ray laser in Pd-like xenon is feasible in the extremely wide range of atomic densities: 1017≤[Xe8+]≤ 3 x 1019 cm-3. This result is due to the large cross sections (and rates) of level excitations in Pd-like xenon by electron impact. We propose a highly efficient tabletop x-ray laser pumped by optical-field ionization in a xenon cluster jet. The efficiency of ∼0.5% is possible with a pump laser pulse energy of ≥0.001 J and an intensity of ∼1016 W/cm2.

  3. Soft Condensed Matter

    International Nuclear Information System (INIS)

    The author states in the preface of the book that the aim is '...to give a unified overview of the various aspects of the physics of soft condensed matter'. The book succeeds in fulfilling this aim in many respects. The style is fluent and concise and gives the necessary explanations to make its content understandable to people with some knowledge of the basic principles of physics. The content of the book is complete enough to give a panoramic view of the landscape of soft condensed matter. The first two chapters give, respectively, a short introduction and a presentation of forces, energies and timescales, giving a general overview and pointing out the particular importance of different aspects such as timescales, which are much more important in soft condensed matter than in traditional or 'hard' condensed matter. The next chapter, devoted to phase transition, recalls that the equilibrium between two phases is controlled by free energy considerations. Spinodal decomposition is presented as a counterpart of nucleation and growth. Again, characteristic length scales are considered and applied to a phase separation mixture of polymers in a common solvent. The following three chapters are devoted respectively to specific topics: colloidal dispersion, polymers and gelation. The stability and phase behaviour of colloids are related to the interaction between colloidal particles. Properties of colloidal crystals as well as colloidal dispersion are depicted in terms of stabilization of crystalline colloids. The flow properties of colloidal dispersion are presented in terms of free energy minimization and the structure of the dispersion. After a brief introduction to polymer chemistry and architecture, the coil-globule transition is discussed. Viscoelasticity of polymers is described and discussed by introducing the notion of entanglement. This leads to the introduction of the tube model and the theory of reptation. The sol-gel transition is presented phenomenologically

  4. Common mathematical framework for real and synthetic aperture by interferometry radiometers

    OpenAIRE

    Bosch Lluís, Xavier; Ramos Pérez, Isaac; Camps Carmona, Adriano José; Rodríguez Álvarez, Nereida; Valencia Domènech, Enric; Hyuk, Park

    2014-01-01

    This work focuses on the relationship between real and synthetic aperture radiometers giving a general and common mathematical framework for both of them. It will be demonstrated that a real aperture radiometer array can be understood as a synthetic aperture one, with a high level of redundancy. Therefore, all the recent results from synthetic aperture radiometry can be translated to real aperture radiometer arrays. This fact can be used to create beamforming arrays in a ...

  5. The soft side.

    Science.gov (United States)

    Small, Bruce W

    2005-01-01

    For true communication between dentist and patient, a dentist must develop behavioral skills (or "soft" skills) in addition to clinical skills. These skills should be utilized at all times but particularly during a patient's initial visit. Educating the patient is mandatory and the dentist should never offer solutions to problems that the patient cannot see, feel, or understand. If these ideas are kept paramount at all times they will become normal operating procedure and not seem artificial. Caring about the patient and remaining committed to technical excellence will go a long way toward the delivery of quality care. PMID:15779215

  6. Numerical Simulation of Transient Gauss pulse Coupling through Small Apertures

    Directory of Open Access Journals (Sweden)

    Jinshi Xiao

    2011-08-01

    Full Text Available Transient electromagnetic pulse (EMP can easily couple into equipments through small apertures in its shells. To study the coupling effects of transient Gauss pulse to a cubic cavity with openings, coupling course is simulated using sub-gridding finite difference in time domain (FDTD algorithm in this paper. A new grid partition approach is provided to simulate each kind of apertures with complex shapes. With this approach, the whole calculation space is modeled, and six kinds of aperture with different shapes are simulated. Coupling course is simulate in the whole time domain using sub-gridding FDTD approach. Selecting apertures with dimension of several millimeters to research, coupled electric field waveform, power density and coupling coefficient are calculated. The affect on coupling effects by varied incident angle and varied pulse width are also analyzed. The main conclusion includes interior resonance phenomenon, increase effect around rectangle aperture and several distributing rules of coupled electric field in the cavity. The correctness of these results is validated by comparing with other scholars’ results. These numerical results can help us to understand coupling mechanism of the transient Gauss pulse.

  7. Aperture referral in dioptric systems with stigmatic elements

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2012-12-01

    Full Text Available A previous paper develops the general theory of aperture referral in linear optics and shows how several ostensibly distinct concepts, including the blur patch on the retina, the effective cornealpatch, the projective field and the field of view, are now unified as particular applications of the general theory.  The theory allows for astigmatism and heterocentricity.  Symplecticity and the generality of the approach, however, make it difficult to gain insight and mean that the material is not accessible to readers unfamiliar with matrices and linear algebra. The purpose of this paper is to examine whatis, perhaps, the most important special case, that in which astigmatism is ignored.  Symplecticity and, hence, the mathematics become greatly simplified. The mathematics reduces largely to elementary vector algebra and, in some places, simple scalar algebra and yet retains the mathematical form of the general approach.  As a result the paper allows insight into and provides a stepping stone to the general theory.  Under referral an aperture under-goes simple scalar magnification and transverse translation.  The paper pays particular attention to referral to transverse planes in the neighbourhood of a focal point where the magnification may be positive, zero or negative.  Circular apertures are treated as special cases of elliptical apertures and the meaning of referred apertures of negative radius is explained briefly. (S Afr Optom 2012 71(1 3-11

  8. Architecture design for soft errors

    CERN Document Server

    Mukherjee, Shubu

    2008-01-01

    This book provides a comprehensive description of the architetural techniques to tackle the soft error problem. It covers the new methodologies for quantitative analysis of soft errors as well as novel, cost-effective architectural techniques to mitigate them. To provide readers with a better grasp of the broader problem deffinition and solution space, this book also delves into the physics of soft errors and reviews current circuit and software mitigation techniques.

  9. Deployable Soft Composite Structures.

    Science.gov (United States)

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-01-01

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel. PMID:26892762

  10. Modeling Soft Matter

    Science.gov (United States)

    Kremer, Kurt

    Soft matter science or soft materials science is a relatively new term for the science of a huge class of rather different materials such as colloids, polymers (of synthetic or biological origin), membranes, complex molecular assemblies, complex fluids, etc. and combinations thereof. While many of these systems are contained in or are even the essential part of everyday products ("simple" plastics such as yoghurt cups, plastic bags, CDs, many car parts; gels and networks such as rubber, many low fat foods, "gummi" bears; colloidal systems such as milk, mayonnaise, paints, almost all cosmetics or body care products, the border lines between the different applications and systems are of course not sharp) or as biological molecules or assemblies (DNA, proteins, membranes and cytoskeleton, etc.) are central to our existence, others are basic ingredients of current and future high tech products (polymers with specific optical or electronic properties, conducting macromolecules, functional materials). Though the motivation is different in life science rather than in materials science biomolecular simulations, the basic structure of the problems faced in the two fields is very similar.

  11. Deployable Soft Composite Structures

    Science.gov (United States)

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-02-01

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.

  12. Deployable Soft Composite Structures.

    Science.gov (United States)

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon

    2016-02-19

    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.

  13. Apodized Pupil Lyot Coronagraphs for Arbitrary Telescope Apertures

    CERN Document Server

    Soummer, R

    2004-01-01

    In the context of high dynamic range imaging, this study presents a breakthrough for the understanding of Apodized Pupil Lyot Coronagraphs, making them available for arbitrary aperture shapes. These new solutions find immediate application in current, ground-based coronagraphic studies (Gemini, VLT) and in existing instruments (AEOS Lyot Project). They also offer the possiblity of a search for an on-axis design for TPF. The unobstructed aperture case has already been solved by Aime et al. (2002) and Soummer et al. (2003). Analytical solutions with identical properties exist in the general case and, in particular, for centrally obscured apertures. Chromatic effects can be mitigated with a numerical optimization. The combination of analytical and numerical solutions enables the study of the complete parameter space (central obstruction, apodization throughput, mask size, bandwidth, and Lyot stop size).

  14. Synthetic aperture integration (SAI) algorithm for SAR imaging

    Science.gov (United States)

    Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

    2013-07-09

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

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

    CERN Document Server

    Buscher, David F

    2015-01-01

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

  16. Experimental investigation of synthetic aperture flow angle estimation

    DEFF Research Database (Denmark)

    Oddershede, Niels; Jensen, Jørgen Arendt

    2005-01-01

    Currently synthetic aperture flow methods can find the correct velocity magnitude, when the flow direction is known. To make a fully automatic system, the direction should also be estimated. Such an approach has been suggested by Jensen (2004) based on a search of the highest cross-correlation as......Currently synthetic aperture flow methods can find the correct velocity magnitude, when the flow direction is known. To make a fully automatic system, the direction should also be estimated. Such an approach has been suggested by Jensen (2004) based on a search of the highest cross......-correlation as a function of velocity and angle. This paper presents an experimental investigation of this velocity angle estimation method based on a set of synthetic aperture flow data measured using our RASMUS experimental ultrasound system. The measurements are performed for flow angles of 60, 75, and 90 deg...

  17. Smart antennas for space-borne synthetic aperture radars

    Science.gov (United States)

    Qin, F.; Gao, S.; Mao, C.; Wang, Z.; Patyuchenko, A.; Younis, M.; Krieger, G.

    2015-11-01

    This paper discusses smart antennas for space-borne synthetic aperture radar (SAR). First, some recent development in smart antennas for space-borne SAR is reviewed. Then, the paper presents a low-cost space-borne SAR system using digital beam forming on receive. The smart antenna system is also discussed, and some results are shown. The antenna system, consisting of a parabolic reflector and multi-feed array, is designed and optimized for dual-band dual-polarized digital beam-forming performance. The operating frequencies are at X and Ka bands with the center frequency of 9.6 and 35.75 GHz, respectively. The stacked dipoles and square patches with parasitic elements are employed as the feed elements at X and Ka bands. Dual-band antenna arrays are combined in the same aperture, which not only reduce the aperture of the feed array, but also coincide the center of dual-band feed arrays.

  18. An Aperture Photometry Pipeline for K2 Data

    Science.gov (United States)

    Buzasi, Derek L.; Carboneau, Lindsey; Lezcano, Andy; Vydra, Ekaterina

    2016-01-01

    As part of an ongoing research program with undergraduate students at Florida Gulf Coast University, we have constructed an aperture photometry pipeline for K2 data. The pipeline performs dynamic automated aperture mask definition for all targets in the K2 fields, followed by aperture photometry and detrending. Our pipeline is currently used to support a number of projects, including studies of stellar rotation and activity, red giant asteroseismology, gyrochronology, and exoplanet searches. In addition, output is used to support an undergraduate class on exoplanets aimed at a student audience of both majors and non-majors. The pipeline is designed for both batch and single-target use, and is easily extensible to data from other missions, and pipeline output is available to the community. This paper will describe our pipeline and its capabilities and illustrate the quality of the results, drawing on all of the applications for which it is currently used.

  19. Coronagraph-Integrated Wavefront Sensing with a Sparse Aperture Mask

    CERN Document Server

    Subedi, Hari; Kasdin, N Jeremy; Cavanagh, Kathleen; Riggs, A J Eldorado

    2015-01-01

    Stellar coronagraph performance is highly sensitive to optical aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph such as tip-tilt, defocus and coma must be determined and compensated. Previous authors have established the utility of pupil-plane masks (both non-redundant/sparse-aperture and generally asymmetric aperture masks) for wavefront sensing. Here we show how a sparse aperture mask (SAM) can be integrated with a coronagraph to measure low-order, differential phase aberrations. Starlight rejected by the coronagraph's focal plane stop is collimated to a relay pupil, where the mask forms an interference fringe pattern on a subsequent detector. Our numerical Fourier propagation models show that the information encoded in the fringe intensity distortions is sufficient to accurately discriminate and estimate Zernike phase modes extending from tip-tilt up to radial degree $n=5$, with amplitude up to $\\lambda/20$ RM...

  20. A twin aperture resistive quadrupole for the LHC

    CERN Document Server

    Clark, G S; de Rijk, G; Racine, M

    2000-01-01

    The European Organization for Nuclear Research (CERN) is constructing the Large Hadron Collider (LHC). The LHC's cleaning insertions require 48 twin aperture resistive quadrupoles. These 3.1 m long magnets have a gradient of 35 T/m for an inscribed circle of 46 mm diameter and an aperture separation distance of 224 mm. This magnet project is part of the Canadian contribution to the LHC. A prototype magnet was delivered in May 1998 and measured at CERN. Design changes were made based on the results. Due to the small apertures and the complicated geometry, the mechanical precision of the laminations and stacks is the main issue in the production of these quadrupoles. Series production will start in October 1999. The design and the measurement results are described in this paper. (1 refs).

  1. Motion compensated beamforming in synthetic aperture vector flow imaging

    DEFF Research Database (Denmark)

    Oddershede, Niels; Jensen, Jørgen Arendt

    2006-01-01

    . Here the SNR is -10 dB compared to the stationary scatterer. A 2D motion compensation method for synthetic aperture vector flow imaging is proposed, where the former vector velocity estimate is used for compensating the beamforming of new data. This method is tested on data from an experimental flow......In synthetic aperture imaging the beamformed data from a number of emissions are summed to create dynamic focusing in transmit. This makes the method susceptible to motion, which is especially the case for the synthetic aperture flow estimation method, where large movements are expected......) of the beamformed response from the scatterer at all velocities is compared to that of a stationary scatterer. For lateral movement, the SNR drops almost linearly with velocity to -4 dB at I m/s, while for axial movement the SNR drop is largest, when the scatterer moves a quarter of a wavelength between emissions...

  2. A new method of aperture synthetizing in digital holography

    Institute of Scientific and Technical Information of China (English)

    Zhang Qing-Sheng; Lü Xiao-Xu; Yu Qing-Ting; Liu Gan-Yong

    2009-01-01

    This paper proposes a new method of aperture synthetizing in digital holography based on the principle of holography. In the new method aperture synthetizing is achieved by reconstructing each sub-hologram respectively, firstly,moving each reconstructed wave field referred to the benchmark reconstructed wave field according to the relationship between spacial motion and frequency shift, and finally splicing them by using superposition. Two different recording ways, using plane wave to record and using spherical wave to record, are analyzed, and their moving formula is deduced,too. Simulation and experiment are done. The results show that in comparison with the traditional method of aperture synthetizing in digital holography, the new method can decrease calculation and save reconstructed time obviously which has better applicability.

  3. X-ray lenses with large aperture; Roentgenlinsen mit grosser Apertur

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Markus

    2010-07-01

    Up to now, most X-ray imaging setups are based on absorption contrast imaging. There is a demand for focused X-rays in many X-ray analysis applications, either to increase the resolution of an imaging system, or, to reduce the time effort of an experiment through higher photon flux. For photon energies higher than 15 keV refractive X-ray optics are more efficient in comparison to non-refractive X-ray optics. The aim of this work was to develop X-ray lenses with large apertures and high transparency. By increasing the number of refracting surfaces while removing unnecessary lens material such lenses have been developed. Utilizing this approach the overall beam deflection angle is large with respect to the lens material it propagates through and so the transparency of the lens is increased. Within this work, X-ray lenses consisting of several thousands of prisms with an edge length in the range of micrometers have been developed and fabricated by deep X-ray lithography. Deep X-ray lithography enables high precision microstrucures with smooth sidewalls and large aspect ratios. The aperture of high-transparency X-ray lenses made this way is greater than 1 mm. They are suitable for photon energies in the range of 8 keV to 24 keV and offer a focal width of smaller than 10 {mu}m at a transparency of around 40%. Furthermore, rolled X-ray lenses have been developed, that are made out of a microstructured polyimide film, which is cut according to the requirements regarding focal length and photon energy. The microstructured film is fabricated by molding, using an anisotropically etched silicon wafer as molding tool. Its mean roughness is in the range of nanometers. The film features prismatic structures, its surface topology is similar to an asparagus field. The measured diameter of the point focus was 18 {mu}m to 31 {mu}m, the calculated opticla efficiency was 37%. Future work will concentrate on increasing the aspect ratio of Prism Lenses and on increasing the rolling

  4. In-vivo evaluation of convex array synthetic aperture imaging

    DEFF Research Database (Denmark)

    Pedersen, Morten Høgholm; Gammelmark, Kim Løkke; Jensen, Jørgen Arendt

    2007-01-01

    This paper presents an in-vivo study of synthetic transmit aperture (STA) imaging in comparison to conventional imaging, evaluating whether STA imaging is feasible in-vivo, and whether the image quality obtained is comparable to traditional scanned imaging in terms of penetration depth, spatial...... element aperture was used in transmit and receive with a 1.5 cycle sinusoid excitation pulse. Conventional and STA images were acquired interleaved ensuring that the exact same anatomical location was scanned. Image sequences were recorded in real-time and processed off-line. Seven male volunteers were...

  5. Performance of Synthetic Aperture Compounding for in-vivo imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2011-01-01

    A method for synthetic aperture compounding (SAC) is applied to data from water tank measurements, data from a tissue-mimicking phantom, and clinical data from the abdomen of a healthy 27 year old male. Further, using this method compounding can be obtained without any loss in temporal resolution....... The water tank measurements reveal an improved detail resolution of 45% when comparing SAC to conventional compounding and an improvement of 22%, when comparing to synthetic aperture (SA) imaging. The cystic resolution at 12 dB is improved by 50% and 12% when comparing SAC to conventional compounding...

  6. Synthetic Aperture Sequential Beamformation applied to medical imaging.

    OpenAIRE

    Hemmsen, Martin Christian; Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is applied to medical ultrasound imaging using a multi element convex array transducer. The main motivation for SASB is to apply synthetic aperture techniques without the need for storing RF-data for a number of elements and hereby devise a system with a reduced system complexity. Using a 192 element, 3.5 MHz, λ-pitch transducer, it is demonstrated using tissue-phantom and wire-phantom measurements, how the speckle size and the detail resolutio...

  7. Radio Astronomy Transformed: Aperture Arrays - Past, Present & Future

    OpenAIRE

    Garrett, Michael A.

    2012-01-01

    I review the early development of Aperture Arrays and their role in radio astronomy. The demise of this technology at the end of the 1960's, and the reasons for the rise of parabolic dishes is also considered. The parallels with the Antikythera mechanism (see these proceedings) as a lost technology are briefly presented. Aperture Arrays re-entered the world of radio astronomy as the idea to build a huge radio telescope with a collecting area of one square kilometre (the Square Kilometre Array...

  8. Synthetic aperture radar system design for random field classification

    Science.gov (United States)

    Harger, R. O.

    1973-01-01

    An optimum design study is carried out for synthetic aperture radar systems intended for classifying randomly reflecting areas (such as agricultural fields) characterized by a reflectivity density spectral density. The problem solution is obtained, neglecting interfield interference and assuming areas of known configuration and location, as well as a certain Gaussian signal field property. The optimum processor is nonlinear, but includes conventional matched filter processing. A set of summary design curves is plotted, and is applied to the design of a satellite synthetic aperture radar system.

  9. The baffle aperture region of an ion thruster

    International Nuclear Information System (INIS)

    During the period of this research project, electron bombardment ion thrusters have passed from an advanced state of development to highly successful flight demonstrations (e.g. Deep Space 1). Such advances made by NASA have been quickly followed in the commercial sector (e.g. NSSK of communications satellites). In the next few years, these early successes will be followed by many new electric propulsion missions, planned by the world's space agencies and commercial space organisations. These early successes will spawn more ambitious and demanding missions, necessitating thrusters of different power demands, thrusts and sizes. Scaling of the UK series of electron bombardment ion thrusters has previously been carried out by semi- empirical scaling laws. These scaling laws have worked well within a certain range of thruster sizes with some iterative redesign necessary to produce acceptable efficiencies. However, when scaling beyond the ranges of the T5, T6 and UK25, the current scaling laws cannot be used due to the conflicting requirements of magnetic field strength in the discharge chamber and baffle aperture region. The baffle aperture region contains a plasma double layer that accelerates primary electrons into the discharge chamber and thus controls ionisation in the ion thruster. Previously, the baffle aperture region was poorly understood. An extensive and unique experimental investigation of the plasma properties around this critical baffle aperture region has been carried out using Langmuir probes. The externally applied magnetic field has been mapped and the Langmuir probe results have been validated using emissive probes. Results are presented on both argon and xenon propellant and high- resolution maps of an extensive range of plasma properties are plotted over a continuous area from the coupling plasma, through the baffle aperture and into the discharge plasma. Maps were taken over a unique and wide range of thruster operating conditions in which all

  10. Polarimetric synthetic aperture radar data and the complex Wishart distribution

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2003-01-01

    When working with multi-look fully polarimetric synthetic aperture radar (SAR) data an appropriate way of representing the backscattered signal consists of the so-called covariance matrix. For each pixel this is a 3 by 3 Hermitian, positive definite matrix which follows a complex Wishart distribu......When working with multi-look fully polarimetric synthetic aperture radar (SAR) data an appropriate way of representing the backscattered signal consists of the so-called covariance matrix. For each pixel this is a 3 by 3 Hermitian, positive definite matrix which follows a complex Wishart...

  11. A fast autofocus algorithm for synthetic aperture radar processing

    DEFF Research Database (Denmark)

    Dall, Jørgen

    1992-01-01

    High-resolution synthetic aperture radar (SAR) imaging requires the motion of the radar platform to be known very accurately. Otherwise, phase errors are induced in the processing of the raw SAR data, and bad focusing results. In particular, a constant error in the measured along-track velocity...... or the cross-track acceleration leads to a phase error that varies quadratically over the synthetic aperture. The process of estimating this quadratic phase error directly from the radar data is termed autofocus. A novel autofocus algorithm with a computational complexity which is at least an order...

  12. Not-so-Soft Skills

    Science.gov (United States)

    Curran, Mary

    2010-01-01

    Much recent discussion about the skills needed to secure Britain's economic recovery has focused on skills for employability. However, too often, these fundamental skills are understood in narrow functional or vocational terms. So-called "soft skills", what Penelope Tobin, in her 2008 paper "Soft Skills: the hard facts", terms "traits and…

  13. Soft Costs Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-05-01

    This fact sheet is an overview of the systems integration subprogram at the U.S. Department of Energy SunShot Initiative. Soft costs can vary significantly as a result of a fragmented energy marketplace. In the U.S., there are 18,000 jurisdictions and 3,000 utilities with different rules and regulations for how to go solar. The same solar equipment may vary widely in its final installation price due to process and market variations across jurisdictions, creating barriers to rapid industry growth. SunShot supports the development of innovative solutions that enable communities to build their local economies and establish clean energy initiatives that meet their needs, while at the same time creating sustainable solar market conditions.

  14. Soft matter physics

    CERN Document Server

    Williams, Claudine

    1999-01-01

    What do colloids, fractals, liquid crystals, and polymers have in common? Nothing at first sight. Yet the distance scales, the energy transfers, the way these objects react to an external field are very similar. For the first time, this book offers an introduction to the physics of these soft materials in one single volume. A variety of experiments and concepts are presented, including the phenomena of capillarity and wetting, fractals, small volumes and large surfaces, colloids, surfactants, giant micelles and fluid membranes, polymers, and liquid crystals. Each chapter is written by experts in the field with the aim of making the book accessible to the widest possible scientific audience: graduate students, lecturers, and research scientists in physics, chemistry, and other disciplines. Nobel Prize winner Pierre-Gilles de Gennes inspired this book and has written a foreword.

  15. Soft isostasy in geomorphology

    Directory of Open Access Journals (Sweden)

    Mohsen Pourkhosravani

    2012-01-01

    Full Text Available Earth subsidence has been one of the important issues jeopardizing environment and there are many studies, which blame shortage of underground water resources for having uplift and subsidence. However, many argue such conclusion and believe that earth subsidence has been studied in the past without considering the changes in the hill over a long period. In this study, we use SAR interferometry study to investigate earth subsidence in dessert areas of Esfahan, Yazd and Ardakan, located in central part of Iran. The results indicate that there are more important issues affecting subsidence such as the uplift in the hills located the desert area. The results of the survey based on SAR interferometry reveals that subsidence occurs with the uplift in the adjacent hills, simultaneously. In other words, tectonic movements and soft isostasy play important role on earth subsidence.

  16. Soft rocks in Argentina

    Institute of Scientific and Technical Information of China (English)

    Giambastiani; Mauricio

    2014-01-01

    Soft rocks are a still fairly unexplored chapter in rock mechanics. Within this category are the clastic sedimentary rocks and pyroclastic volcanic rocks, of low to moderate lithification (consolidation, cemen-tation, new formed minerals), chemical sedimentary rocks and metamorphic rocks formed by minerals with Mohs hardness less than 3.5, such as limestone, gypsum, halite, sylvite, between the first and phyllites, graphitic schist, chloritic shale, talc, etc., among the latter. They also include any type of rock that suffered alteration processes (hydrothermal or weathering). In Argentina the study of low-strength rocks has not received much attention despite having extensive outcrops in the Andes and great impact in the design criteria. Correlation between geomechanical properties (UCS, deformability) to physical index (porosity, density, etc.) has shown promising results to be better studied. There are many studies and engineering projects in Argentina in soft rock geological environments, some cited in the text (Chihuído dam, N. Kirchner dam, J. Cepernic Dam, etc.) and others such as International Tunnel in the Province of Mendoza (Corredor Bioceánico), which will require the valuable contribution from rock mechanics. The lack of consistency between some of the physical and mechanical parameters explored from studies in the country may be due to an insufficient amount of information and/or non-standardization of criteria for testing materials. It is understood that more and better academic and professional efforts in improv-ing techniques will result in benefits to the better understanding of the geomechanics of weak rocks.

  17. New Double Soft Emission Theorems

    CERN Document Server

    Cachazo, Freddy; Yuan, Ellis Ye

    2015-01-01

    We study the behavior of the tree-level S-matrix of a variety of theories as two particles become soft. By analogy with the recently found subleading soft theorems for gravitons and gluons, we explore subleading terms in double soft emissions. We first consider double soft scalar emissions and find subleading terms that are controlled by the angular momentum operator acting on hard particles. The order of the subleading theorems depends on the presence or not of color structures. Next we obtain a compact formula for the leading term in a double soft photon emission. The theories studied are a special Galileon, DBI, Einstein-Maxwell-Scalar, NLSM and Yang-Mills-Scalar. We use the recently found CHY representation of these theories in order to give a simple proof of the leading order part of all these theorems

  18. Soft Tissue Sarcomas and Agent Orange

    Science.gov (United States)

    ... ZIP code here Soft Tissue Sarcomas and Agent Orange VA presumes some soft tissue sarcomas in Veterans are related to their exposure to Agent Orange or other herbicides during military service. The soft ...

  19. Lessons learned from the first U.S./Russian Federation joint tabletop exercise to prepare for conducting on-site inspections under the Comprehensive Nuclear Test Ban Treaty; TOPICAL

    International Nuclear Information System (INIS)

    A U.S./Russian Federation Joint Tabletop Exercise took place in Snezhinsk, Russia, from 19 to 24 October 1998, whose objectives were the following: (1) To simulate the actions of the Inspection Team (IT), including interactions with the inspected State Party (ISP), in order to examine different ways the United States and Russian Federation (RF) approach inspections and develop appropriate recommendations for the international community. (2) To identify ambiguities and contradictions in the interpretation of Treaty and Protocol provisions that might become apparent in the course of an inspection and that need clarification in connection with the development of Operational Manuals and on-site inspection (OSI) infrastructure. (3) To confirm the efficacy of using bilateral tabletop exercises to assist in developing an effective Comprehensive Test Ban Treaty (CTBT) verification regime. (4) To identify strong and weak points in the preparation and implementation methods of such exercises for the purpose of further improving possible future exercises

  20. Development of laser deposited multilayer zone plate structures for soft X-ray radiation

    Energy Technology Data Exchange (ETDEWEB)

    Liese, Tobias; Radisch, Volker; Knorr, Inga [Institut fuer Materialphysik, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Reese, Michael; Grossmann, Peter; Mann, Klaus [Laser-Laboratorium Goettingen e.V., Hans-Adolf-Krebs-Weg 1, 37077 Goettingen (Germany); Krebs, Hans-Ulrich, E-mail: krebs@ump.gwdg.de [Institut fuer Materialphysik, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2011-04-01

    As a novel approach, the combination of pulsed laser deposition and focused ion beam was applied to fabricate different types of multilayer zone plate structures for soft X-ray applications. For this purpose, high quality non-periodic ZrO{sub 2}/Ti multilayers were deposited by pulsed laser deposition on planar Si substrates and on rotating steel wires with layer thicknesses according to the Fresnel zone plate law. Linear focusing optics were fabricated by cutting slices out of the multilayers by focused ion beam and placing them directly over pinholes within Si{sub 3}N{sub 4} substrates. Additionally, it was shown that laser deposition of depth-graded multilayers on a wire is also a promising way for building up multilayer zone plates with point focus. First experiments using a table-top X-ray source based on a laser-induced plasma show that the determined focal length and spatial resolution of the fabricated multilayer Laue lens corresponds to the designed optic.

  1. Bistatic Synthetic Aperture Radar Point Spread Function Characteristic Analysis

    Institute of Scientific and Technical Information of China (English)

    HU Cheng; ZENG Tao; ZENG Hai-bin

    2007-01-01

    Based on the point spread function (PSF) theory, the side-lobe extension direction of the impulse response in bistatic synthetic aperture radar (BSAR) is analyzed in detail;in addition, the corresponding auto-focus in BSAR should be considered along iso-range direction, not the traditional azimuth resolution (AR) direction.The conclusion is verified by the computer simulation.

  2. Linear synthetic aperture focusing using ultrasonic contact transducers

    International Nuclear Information System (INIS)

    Synthetic aperture processing performed on linear scans with contact ultrasonic transducers can yield useful improvements in lateral resolution of deeply buried defects. Degradation in resolution caused by adverse surface conditions can be minimised by a simple pre-processing normalisation technique. (author)

  3. Synthetic Aperture Flow Imaging Using a Dual Stage Beamformer Approach

    DEFF Research Database (Denmark)

    Li, Ye; Jensen, Jørgen Arendt

    2010-01-01

    Synthetic aperture flow estimation has several advantages compared to the conventional flow estimation however this requires a high number of calculations. A dual beamformer approach is proposed to lower the number of calculations and maintain a beamforming quality sufficient for flow estimation...

  4. Synthetic tracked aperture ultrasound imaging: design, simulation, and experimental evaluation.

    Science.gov (United States)

    Zhang, Haichong K; Cheng, Alexis; Bottenus, Nick; Guo, Xiaoyu; Trahey, Gregg E; Boctor, Emad M

    2016-04-01

    Ultrasonography is a widely used imaging modality to visualize anatomical structures due to its low cost and ease of use; however, it is challenging to acquire acceptable image quality in deep tissue. Synthetic aperture (SA) is a technique used to increase image resolution by synthesizing information from multiple subapertures, but the resolution improvement is limited by the physical size of the array transducer. With a large F-number, it is difficult to achieve high resolution in deep regions without extending the effective aperture size. We propose a method to extend the available aperture size for SA-called synthetic tracked aperture ultrasound (STRATUS) imaging-by sweeping an ultrasound transducer while tracking its orientation and location. Tracking information of the ultrasound probe is used to synthesize the signals received at different positions. Considering the practical implementation, we estimated the effect of tracking and ultrasound calibration error to the quality of the final beamformed image through simulation. In addition, to experimentally validate this approach, a 6 degree-of-freedom robot arm was used as a mechanical tracker to hold an ultrasound transducer and to apply in-plane lateral translational motion. Results indicate that STRATUS imaging with robotic tracking has the potential to improve ultrasound image quality. PMID:27088108

  5. In Vivo Evaluation of Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Hansen, Peter Møller; Lange, Theis;

    2012-01-01

    Ultrasound in vivo imaging using synthetic aperture sequential beamformation (SASB) is compared with conventional imaging in a double blinded study using side-by-side comparisons. The objective is to evaluate if the image quality in terms of penetration depth, spatial resolution, contrast and...

  6. Implementation of Synthetic Aperture Imaging in Medical Ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Kortbek, Jacob; Nikolov, Svetoslav;

    2010-01-01

    The main advantage of medical ultrasound imaging is its real time capability, which makes it possible to visualize dynamic structures in the human body. Real time synthetic aperture imaging puts very high demands on the hardware, which currently cannot be met. A method for reducing the number of...

  7. Characterization of a dense aperture array for radio astronomy

    Science.gov (United States)

    Torchinsky, S. A.; Olofsson, A. O. H.; Censier, B.; Karastergiou, A.; Serylak, M.; Picard, P.; Renaud, P.; Taffoureau, C.

    2016-05-01

    EMBRACE@Nançay is a prototype instrument consisting of an array of 4608 densely packed antenna elements creating a fully sampled, unblocked aperture. This technology is proposed for the Square Kilometre Array and has the potential of providing an extremely large field of view making it the ideal survey instrument. We describe the system, calibration procedures, and results from the prototype.

  8. Characterization of a dense aperture array for radio astronomy

    CERN Document Server

    Torchinsky, S A; Censier, B; Karastergiou, A; Serylak, M; Picard, P; Renaud, P; Taffoureau, C

    2016-01-01

    EMBRACE@Nancay is a prototype instrument consisting of an array of 4608 densely packed antenna elements creating a fully sampled, unblocked aperture. This technology is proposed for the Square Kilometre Array and has the potential of providing an extremely large field of view making it the ideal survey instrument. We describe the system,calibration procedures, and results from the prototype.

  9. Data Collection via Synthetic Aperture Radiometry towards Global System

    Directory of Open Access Journals (Sweden)

    Ali. A. J.Al-Sabbagh

    2015-10-01

    Full Text Available Nowadays it is widely accepted that remote sensing is an efficient way of large data management philosophy. In this paper, we present a future view of the big data collection by synthetic aperture radiometry as a passive microwave remote sensing towards building a global monitoring system. Since the collected data may not have any value, it is mandatory to analyses these data in order to get valuable and beneficial information with respect to their base data. The collected data by synthetic aperture radiometry is one of the high resolution earth observation, these data will be an intensive problems, Meanwhile, Synthetic Aperture Radar able to work in several bands, X, C, S, L and P-band. The important role of synthetic aperture radiometry is how to collect data from areas with inadequate network infrastructures where the ground network facilities were destroyed. The future concern is to establish a new global data management system, which is supported by the groups of international teams working to develop technology based on international regulations. There is no doubt that the existing techniques are so limited to solve big data problems totally. There is a lot of work towards improving 2- D and 3-D SAR to get better resolution.

  10. Radio Astronomy Transformed: Aperture Arrays - Past, Present & Future

    CERN Document Server

    Garrett, Michael A

    2012-01-01

    I review the early development of Aperture Arrays and their role in radio astronomy. The demise of this technology at the end of the 1960's, and the reasons for the rise of parabolic dishes is also considered. The parallels with the Antikythera mechanism (see these proceedings) as a lost technology are briefly presented. Aperture Arrays re-entered the world of radio astronomy as the idea to build a huge radio telescope with a collecting area of one square kilometre (the Square Kilometre Array, SKA) arose. Huge ICT technology advances had transformed Aperture Arrays in terms of their capability, flexibility and reliability. In the mid-1990s, ASTRON started to develop and experiment with the first high frequency aperture array tiles for radio astronomy - AAD, OSMA, THEA & EMBRACE. In the slipstream of these efforts, Phased Array Feeds (PAFs) for radio astronomy were invented and LOFAR itself emerged as a next generation telescope and a major pathfinder for the SKA. Meanwhile, the same advantages that apertu...

  11. Multi element synthetic aperture transmission using a frequency division approach

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jensen, Jørgen Arendt

    2003-01-01

    can therefore be used for flow imaging, unlike with Hadamard and Golay coding. The frequency division approach increases the SNR by a factor of N2 compared to conventional pulsed synthetic aperture imaging, provided that N transmission centers are used. Simulations and phantom measurements...

  12. [Enlargement of the buccal aperture via. Technical consideration (author's transl)].

    Science.gov (United States)

    Pons, J; Pasturel, A; Pochan, Y; Barbier, M

    1979-01-01

    For a long time we know that it is possible to take out from the mouth a part or all the mandibule which presents a local malignant tumour. When the tumour is too extensed, the buccal aperture can be enlarged. The authors describe a new surgical technique which resolves this problem with notable and faithful advantages.

  13. Wind retrieval from synthetic aperture radar - an overview

    DEFF Research Database (Denmark)

    Dagestad, Knut-Frode; Horstmann, Jochen; Mouche, Alexis;

    2013-01-01

    This paper represents a consensus on the state-of-the-art in wind retrieval using synthetic aperture radar (SAR), after the SEASAR 2012 workshop “Advances in SAR Oceanography” hosted by the European Space Agency (ESA) and the Norwegian Space Centre in Tromsø, Norway 18–22 June 2012. We document t...

  14. Aperture alignment in autocollimator-based deflectometric profilometers.

    Science.gov (United States)

    Geckeler, R D; Artemiev, N A; Barber, S K; Just, A; Lacey, I; Kranz, O; Smith, B V; Yashchuk, V V

    2016-05-01

    During the last ten years, deflectometric profilometers have become indispensable tools for the precision form measurement of optical surfaces. They have proven to be especially suitable for characterizing beam-shaping optical surfaces for x-ray beamline applications at synchrotrons and free electron lasers. Deflectometric profilometers use surface slope (angle) to assess topography and utilize commercial autocollimators for the contactless slope measurement. To this purpose, the autocollimator beam is deflected by a movable optical square (or pentaprism) towards the surface where a co-moving aperture limits and defines the beam footprint. In this paper, we focus on the precise and reproducible alignment of the aperture relative to the autocollimator's optical axis. Its alignment needs to be maintained while it is scanned across the surface under test. The reproducibility of the autocollimator's measuring conditions during calibration and during its use in the profilometer is of crucial importance to providing precise and traceable angle metrology. In the first part of the paper, we present the aperture alignment procedure developed at the Advanced Light Source, Lawrence Berkeley National Laboratory, USA, for the use of their deflectometric profilometers. In the second part, we investigate the topic further by providing extensive ray tracing simulations and calibrations of a commercial autocollimator performed at the Physikalisch-Technische Bundesanstalt, Germany, for evaluating the effects of the positioning of the aperture on the autocollimator's angle response. The investigations which we performed are crucial for reaching fundamental metrological limits in deflectometric profilometry. PMID:27250378

  15. Synthetic aperture ultrasound Fourier beamformation using virtual sources

    DEFF Research Database (Denmark)

    Moghimirad, Elahe; Villagómez Hoyos, Carlos Armando; Mahloojifar, Ali;

    2016-01-01

    An efficient Fourier beamformation algorithm is presented for multistatic synthetic aperture ultrasound imaging using virtual sources (FBV). The concept is based on the frequency domain wavenumber algorithm from radar and sonar and is extended to a multi-element transmit/receive configuration using...

  16. Fourier beamformation of multistatic synthetic aperture ultrasound imaging

    DEFF Research Database (Denmark)

    Moghimirad, Elahe; Villagómez Hoyos, Carlos Armando; Mahloojifar, Ali;

    2015-01-01

    A new Fourier beamformation (FB) algorithm is presented for multistatic synthetic aperture ultrasound imaging. It can reduce the number of computations by a factor of 20 compared to conventional Delay-and-Sum (DAS) beamformers. The concept is based on the wavenumber algorithm from radar and sonar...

  17. High numerical aperture all-dielectric metasurface micro-lenses

    NARCIS (Netherlands)

    Silvestri, F.; Gerini, G.; Pisano, E.; Galdi, V.

    2015-01-01

    In this paper, the design principles and the sensitivity analysis needed for the realization of a high numerical aperture metasurface micro-lens are presented. The metasurface micro-lens is realized defining a surface with spatially-variant dielectric resonators embedded in a dielectric bulk. The de

  18. Offshore Wind Potential in South India from Synthetic Aperture Radar

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Bingöl, Ferhat; Badger, Merete;

    The offshore wind energy potential for pre-feasibility in South India in the area from 77° to 80° Eastern longitude and 7° to 10° Northern latitude is observed from a total of 164 ENVISAT Advanced Synthetic Aperture Radar (ASAR) satellite images during the years 2002 to 2011. All satellite scenes...

  19. Millimeter-wave Imaging Systems with Aperture Synthesis Techniques

    DEFF Research Database (Denmark)

    Löffler, Torsten; Krozer, Viktor; Zhurbenko, Vitaliy;

    2010-01-01

    The paper describes development of a millimetre-wave imaging system using multi-element aperture filling techniques [1]. Such imaging systems are increasingly demonstrated for security applications and in particular standoff imaging of persons and bonding flaw and defect detection [2]. The major ...

  20. Velocity estimation using synthetic aperture imaging [blood flow

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a fully...

  1. Imaging blood’s velocity using synthetic aperture ultrasound

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Li, Ye

    2012-01-01

    The blood velocity vector can be estimated using synthetic aperture techniques in medical ultrasound by using short emission sequences. The whole image region is insonified and the flow can be tracked in all directions continuously. This is a major advantage compared to commercial systems, since...

  2. Preliminary comparison of 3D synthetic aperture imaging with Explososcan

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Hansen, Jens Munk; Ferin, Guillaume;

    2012-01-01

    phased array with a pitch of 300 μm, made by Vermon. For both imaging techniques, 289 emissions are used to image a volume spanning 60 in both the azimuth and elevation direction and 150mm in depth. This results for both techniques in a frame rate of 18 Hz. The implemented synthetic aperture technique...

  3. Does the transition to chaos determine the dynamic aperture?

    International Nuclear Information System (INIS)

    We review the important notion of the dynamic aperture of a storage ring with emphasis on its relation to general ideas of dynamical instability, notably the transition to chaos. Practical approaches to the problem are compared. We suggest a somewhat novel quantitative guide to the old problem of choosing machine tunes based on a heuristic blend of KAM theory and resonance selection rules

  4. A circular aperture array for ultrasonic tomography and quantitative NDE

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, S.A.

    1998-08-01

    The main topics of this thesis are ultrasonic tomography and ultrasonic determination of elastic stiffness constants. Both issues are based on a synthetic array with transducer elements distributed uniformly along a circular aperture, i.e., a circular aperture array. The issues are treated both theoretically and experimentally by broadband pulse techniques. Ultrasonic tomography, UCT, from a circular aperture is a relatively new imaging technique in Non-destructive Evaluation (NDE) to acquire cross sectional images in bulk materials. A filtered back-projection algorithm is used to reconstruct images in four different experiments and results of attenuation, velocity and reflection tomograms in Plexiglas of AlSi-alloy cylinders are presented. Two kinds of ultrasonic tomography are introduced: bistatic and monostatic imaging. Both techniques are verified experimentally by Plexiglas cylinders. Different reconstruction artifacts are discussed and theoretical resolution constraints are discussed for various configurations of the circular aperture array. The monostatic technique is used in volumetric imaging. In the experimental verification artificial and real discontinuities in a cylindrical AlSi-alloy are compared with similar discontinuities in a Plexiglas specimen. Finally, some limitations to UCT are discussed. The circular aperture array is used to determine five independent elastic stiffness constants of a unidirectional glass/PET (Poly Ethylene Teraphtalate) laminate. Energy flux propagation and attenuation of ultrasonic waves are considered and velocity surfaces are calculated for different planes of interest. Relations between elastic stiffness constants and engineering constants (i.e., Young`s moduli, shear moduli and Poisson`s ratios) are discussed for an orthotropic composite. Six micromechanical theories are reviewed, and expressions predicting the elastic engineering constants are evaluated. The micromechanical predicted elastic stiffness constants for the

  5. Soft Hair on Black Holes.

    Science.gov (United States)

    Hawking, Stephen W; Perry, Malcolm J; Strominger, Andrew

    2016-06-10

    It has recently been shown that Bondi-van der Burg-Metzner-Sachs supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These laws require black holes to carry a large amount of soft (i.e., zero-energy) supertranslation hair. The presence of a Maxwell field similarly implies soft electric hair. This Letter gives an explicit description of soft hair in terms of soft gravitons or photons on the black hole horizon, and shows that complete information about their quantum state is stored on a holographic plate at the future boundary of the horizon. Charge conservation is used to give an infinite number of exact relations between the evaporation products of black holes which have different soft hair but are otherwise identical. It is further argued that soft hair which is spatially localized to much less than a Planck length cannot be excited in a physically realizable process, giving an effective number of soft degrees of freedom proportional to the horizon area in Planck units.

  6. Soft Hair on Black Holes.

    Science.gov (United States)

    Hawking, Stephen W; Perry, Malcolm J; Strominger, Andrew

    2016-06-10

    It has recently been shown that Bondi-van der Burg-Metzner-Sachs supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These laws require black holes to carry a large amount of soft (i.e., zero-energy) supertranslation hair. The presence of a Maxwell field similarly implies soft electric hair. This Letter gives an explicit description of soft hair in terms of soft gravitons or photons on the black hole horizon, and shows that complete information about their quantum state is stored on a holographic plate at the future boundary of the horizon. Charge conservation is used to give an infinite number of exact relations between the evaporation products of black holes which have different soft hair but are otherwise identical. It is further argued that soft hair which is spatially localized to much less than a Planck length cannot be excited in a physically realizable process, giving an effective number of soft degrees of freedom proportional to the horizon area in Planck units. PMID:27341223

  7. Growing and evolving soft robots.

    Science.gov (United States)

    Rieffel, John; Knox, Davis; Smith, Schuyler; Trimmer, Barry

    2014-01-01

    Completely soft and flexible robots offer to revolutionize fields ranging from search and rescue to endoscopic surgery. One of the outstanding challenges in this burgeoning field is the chicken-and-egg problem of body-brain design: Development of locomotion requires the preexistence of a locomotion-capable body, and development of a location-capable body requires the preexistence of a locomotive gait. This problem is compounded by the high degree of coupling between the material properties of a soft body (such as stiffness or damping coefficients) and the effectiveness of a gait. This article synthesizes four years of research into soft robotics, in particular describing three approaches to the co-discovery of soft robot morphology and control. In the first, muscle placement and firing patterns are coevolved for a fixed body shape with fixed material properties. In the second, the material properties of a simulated soft body coevolve alongside locomotive gaits, with body shape and muscle placement fixed. In the third, a developmental encoding is used to scalably grow elaborate soft body shapes from a small seed structure. Considerations of the simulation time and the challenges of physically implementing soft robots in the real world are discussed. PMID:23373976

  8. Soft Hair on Black Holes

    CERN Document Server

    Hawking, Stephen W; Strominger, Andrew

    2016-01-01

    It has recently been shown that BMS supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These laws require black holes to carry a large amount of soft ($i.e.$ zero-energy) supertranslation hair. The presence of a Maxwell field similarly implies soft electric hair. This paper gives an explicit description of soft hair in terms of soft gravitons or photons on the black hole horizon, and shows that complete information about their quantum state is stored on a holographic plate at the future boundary of the horizon. Charge conservation is used to give an infinite number of exact relations between the evaporation products of black holes which have different soft hair but are otherwise identical. It is further argued that soft hair which is spatially localized to much less than a Planck length cannot be excited in a physically realizable process, giving an effective number of soft degrees of freedom proportional to the ho...

  9. Soft Hair on Black Holes

    Science.gov (United States)

    Hawking, Stephen W.; Perry, Malcolm J.; Strominger, Andrew

    2016-06-01

    It has recently been shown that Bondi-van der Burg-Metzner-Sachs supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These laws require black holes to carry a large amount of soft (i.e., zero-energy) supertranslation hair. The presence of a Maxwell field similarly implies soft electric hair. This Letter gives an explicit description of soft hair in terms of soft gravitons or photons on the black hole horizon, and shows that complete information about their quantum state is stored on a holographic plate at the future boundary of the horizon. Charge conservation is used to give an infinite number of exact relations between the evaporation products of black holes which have different soft hair but are otherwise identical. It is further argued that soft hair which is spatially localized to much less than a Planck length cannot be excited in a physically realizable process, giving an effective number of soft degrees of freedom proportional to the horizon area in Planck units.

  10. Soft Decision Analyzer

    Science.gov (United States)

    Steele, Glen; Lansdowne, Chatwin; Zucha, Joan; Schlensinger, Adam

    2013-01-01

    The Soft Decision Analyzer (SDA) is an instrument that combines hardware, firmware, and software to perform realtime closed-loop end-to-end statistical analysis of single- or dual- channel serial digital RF communications systems operating in very low signal-to-noise conditions. As an innovation, the unique SDA capabilities allow it to perform analysis of situations where the receiving communication system slips bits due to low signal-to-noise conditions or experiences constellation rotations resulting in channel polarity in versions or channel assignment swaps. SDA s closed-loop detection allows it to instrument a live system and correlate observations with frame, codeword, and packet losses, as well as Quality of Service (QoS) and Quality of Experience (QoE) events. The SDA s abilities are not confined to performing analysis in low signal-to-noise conditions. Its analysis provides in-depth insight of a communication system s receiver performance in a variety of operating conditions. The SDA incorporates two techniques for identifying slips. The first is an examination of content of the received data stream s relation to the transmitted data content and the second is a direct examination of the receiver s recovered clock signals relative to a reference. Both techniques provide benefits in different ways and allow the communication engineer evaluating test results increased confidence and understanding of receiver performance. Direct examination of data contents is performed by two different data techniques, power correlation or a modified Massey correlation, and can be applied to soft decision data widths 1 to 12 bits wide over a correlation depth ranging from 16 to 512 samples. The SDA detects receiver bit slips within a 4 bits window and can handle systems with up to four quadrants (QPSK, SQPSK, and BPSK systems). The SDA continuously monitors correlation results to characterize slips and quadrant change and is capable of performing analysis even when the

  11. High flux coherent supercontinuum soft X-ray source driven by a single-stage 10 mJ, kHz, Ti:sapphire laser amplifier

    CERN Document Server

    Ding, Chengyuan; Fan, Tingting; Hickstein, Daniel D; Popmintchev, Tenio; Zhang, Xiaoshi; Walls, Mike; Murnane, Margaret M; Kapteyn, Henry C

    2014-01-01

    We demonstrate the highest flux tabletop source of coherent soft X-rays to date, driven by a single-stage 10 mJ Ti:sapphire regenerative amplifier at 1 kHz. We first down-convert the laser to 1.3 um using a parametric amplifier, before up-converting it to soft X-rays using high harmonic generation in a high-pressure, phase matched, hollow waveguide geometry. The resulting optimally phase matched broadband spectrum extends to 200 eV, with a soft X-ray photon flux of > 10^6 photons/pulse/1% bandwidth at 1 kHz, corresponding to > 10^9 photons/s/1% bandwidth, or approximately a three order-of-magnitude increase compared with past work. Finally, using this broad bandwidth X-ray source, we demonstrate X-ray absorption spectroscopy of multiple elements and transitions in molecules in a single spectrum, with a spectral resolution of 0.25 eV, and with the ability to resolve the near edge fine structure.

  12. A Ploidy-Sensitive Mechanism Regulates Aperture Formation on the Arabidopsis Pollen Surface and Guides Localization of the Aperture Factor INP1.

    Directory of Open Access Journals (Sweden)

    Sarah H Reeder

    2016-05-01

    Full Text Available Pollen presents a powerful model for studying mechanisms of precise formation and deposition of extracellular structures. Deposition of the pollen wall exine leads to the generation of species-specific patterns on pollen surface. In most species, exine does not develop uniformly across the pollen surface, resulting in the formation of apertures-openings in the exine that are species-specific in number, morphology and location. A long time ago, it was proposed that number and positions of apertures might be determined by the geometry of tetrads of microspores-the precursors of pollen grains arising via meiotic cytokinesis, and by the number of last-contact points between sister microspores. We have tested this model by characterizing Arabidopsis mutants with ectopic apertures and/or abnormal geometry of meiotic products. Here we demonstrate that contact points per se do not act as aperture number determinants and that a correct geometric conformation of a tetrad is neither necessary nor sufficient to generate a correct number of apertures. A mechanism sensitive to pollen ploidy, however, is very important for aperture number and positions and for guiding the aperture factor INP1 to future aperture sites. In the mutants with ectopic apertures, the number and positions of INP1 localization sites change depending on ploidy or ploidy-related cell size and not on INP1 levels, suggesting that sites for aperture formation are specified before INP1 is brought to them.

  13. A Ploidy-Sensitive Mechanism Regulates Aperture Formation on the Arabidopsis Pollen Surface and Guides Localization of the Aperture Factor INP1.

    Science.gov (United States)

    Reeder, Sarah H; Lee, Byung Ha; Fox, Ronald; Dobritsa, Anna A

    2016-05-01

    Pollen presents a powerful model for studying mechanisms of precise formation and deposition of extracellular structures. Deposition of the pollen wall exine leads to the generation of species-specific patterns on pollen surface. In most species, exine does not develop uniformly across the pollen surface, resulting in the formation of apertures-openings in the exine that are species-specific in number, morphology and location. A long time ago, it was proposed that number and positions of apertures might be determined by the geometry of tetrads of microspores-the precursors of pollen grains arising via meiotic cytokinesis, and by the number of last-contact points between sister microspores. We have tested this model by characterizing Arabidopsis mutants with ectopic apertures and/or abnormal geometry of meiotic products. Here we demonstrate that contact points per se do not act as aperture number determinants and that a correct geometric conformation of a tetrad is neither necessary nor sufficient to generate a correct number of apertures. A mechanism sensitive to pollen ploidy, however, is very important for aperture number and positions and for guiding the aperture factor INP1 to future aperture sites. In the mutants with ectopic apertures, the number and positions of INP1 localization sites change depending on ploidy or ploidy-related cell size and not on INP1 levels, suggesting that sites for aperture formation are specified before INP1 is brought to them. PMID:27177036

  14. Soft Matter under Exogenic Impacts

    CERN Document Server

    Rzoska, Sylwester J

    2007-01-01

    Soft Matter Under Exogenic Impacts’ is fairly unique in supplying a comprehensive presentation of high pressures, negative pressures, random constraints and strong electric field exogenic (external) impacts on various soft matter systems. These are: (i) critical liquids, (ii) glass formers, such as supercooled liquids including water, polymers and resins, (iii) liquid crystals and (iv) bio-liquids. It is, because of this, an excellent guide in this novel and still puzzling research area. Besides new results, the identification of new types of physical behavior, new technological materials, ultimate verification of condensed and soft matter physics models, new applications in geophysics, biophysics, biotechnology, are all discussed in this book.

  15. Millimeter-wave aperture synthesis for remote sensing of the Earth

    OpenAIRE

    Harvey, Andrew R.; Greenaway, Alain H.; Camps Carmona, Adriano José; Bará Temes, Francisco Javier; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Martín Neira, Manuel

    1998-01-01

    Millimetre-wave radiometry of the earth's surface from Low Earth Orbit (LEO) with a resolution of a few km requires antenna apertures several metres across and sub-second scanning times. Fulfilling these requirements with a mechanically scanned real-aperture antenna presents formidable mechanical challenges. An attractive alternative described here is to use synthetic aperture techniques employing a sparse-array of antennas that trade the mechanical complexity of real-aperture imaging for the...

  16. The Design, Implementation, and Performance of the Astro-H SXS Aperture Assembly and Blocking Filters

    Science.gov (United States)

    Kilbourne, C. A.; Adams, J. S.; Arsenovic, P.; Ayers, T.; Chiao, M. P.; DiPirro, M. J.; Eckart, M. E.; Fujimoto, R.; Kazeva, J. D.; Kelley, R. L.; Kripps, K. L.; Lairson, B.; Leutenegger, M. A.; Lopez, H.; McCammon, D.; McGuinness, D. S.; Mitsuda, K.; Moseley, S. J.; Porter, F. S.; Schweiss, A. N.; Takei, Y.; Thorpe, R. S.; Watanabe, T.; Yamasaki, N. Y.; Yoshida, S.

    2016-01-01

    The calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV. The properties that make the SXS a powerful x-ray spectrometer also make it sensitive to the entire electromagnetic band. If characterized as a bolometer, it would have a noise equivalent power (NEP) of < 4x10(exp -18) W/(Hz)0.5. Thus it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. Additionally, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. These needs are addressed by a series of five thin-film radiation blocking filters that block long-wavelength radiation while minimizing x-ray attenuation. The SXS aperture assembly is a system of barriers, baffles, filter carriers, and filter mounts that supports the filters and inhibits their potential contamination. The three warmer filters also were equipped with thermometers and heaters for decontamination.

  17. Cytodiagnosis of soft tissue tumors.

    Science.gov (United States)

    Oland, J; Rosen, A; Reif, R; Sayfan, J; Orda, R

    1988-03-01

    The only acceptable definitive diagnosis of a soft tissue mass is histologic or cytologic examination. In recent years, fine-needle aspiration cytology is used in more and more centers for diagnosis of soft tissue masses. We studied 196 aspiration cytologies performed on soft tissue lesions. Out of these, in 48 cases a definitive surgical procedure or open biopsy for histology and further evaluation were performed. There were 25 sarcomas and 23 benign tumors. There was one false negative cytologic result in this group; no false positive cytologies were detected. It seems that cytodiagnosis of soft tissue masses performed by an experienced pathologist is the method of choice, permitting a good diagnostic evaluation, with almost none of the traumatic and oncologic disadvantages of the other methods of biopsy. PMID:3352270

  18. MICROBIAL DIVERSITY IN SOFT DRINKS

    Directory of Open Access Journals (Sweden)

    A. Shiva Shanker

    2012-06-01

    Full Text Available A total of 4 carbonated soft drink (CSD samples, from various locations in nine places of India were examined to determine their biological quality. Most samples were not in compliance with microbiological standards set by organizations like the World Health Organization (WHO. The prevailing bacterial isolates were Gluconobacter sp., Lactobacillus sp., and Leuconostoc sp. The prevailing fungal isolates were Penicillium expansum and the next isolate was Penicillium roqueforti. Many microorganisms are found in soft drinks as environmental or raw materials contaminants, but relatively can grow within the acidic and low oxygen environment. It is crucial for soft drink manufacturers to inspect raw materials before they are mixed with other ingredients. Concern with consumer health, safety and the environment will continue to have a positive impact on trend in the soft drink industry.

  19. Aperture Effects on the Oxygen Abundance Determinations from CALIFA Data

    Science.gov (United States)

    Iglesias-Páramo, J.; Vílchez, J. M.; Rosales-Ortega, F. F.; Sánchez, S. F.; Duarte Puertas, S.; Petropoulou, V.; Gil de Paz, A.; Galbany, L.; Mollá, M.; Catalán-Torrecilla, C.; Castillo Morales, A.; Mast, D.; Husemann, B.; García-Benito, R.; Mendoza, M. A.; Kehrig, C.; Pérez-Montero, E.; Papaderos, P.; Gomes, J. M.; Walcher, C. J.; González Delgado, R. M.; Marino, R. A.; López-Sánchez, Á. R.; Ziegler, B.; Flores, H.; Alves, J.

    2016-07-01

    This paper aims to provide aperture corrections for emission lines in a sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey (CALIFA) database. In particular, we explore the behavior of the log([O iii] λ5007/Hβ)/([N ii] λ6583/Hα) (O3N2) and log[N ii] λ6583/Hα (N2) flux ratios since they are closely connected to different empirical calibrations of the oxygen abundances in star-forming galaxies. We compute the median growth curves of Hα, Hα/Hβ, O3N2, and N2 up to 2.5R 50 and 1.5 disk {R}{{eff}}. These distances cover most of the optical spatial extent of the CALIFA galaxies. The growth curves simulate the effect of observing galaxies through apertures of varying radii. We split these growth curves by morphological types and stellar masses to check if there is any dependence on these properties. The median growth curve of the Hα flux shows a monotonous increase with radius with no strong dependence on galaxy inclination, morphological type, and stellar mass. The median growth curve of the Hα/Hβ ratio monotonically decreases from the center toward larger radii, showing for small apertures a maximum value of ≈10% larger than the integrated one. It does not show any dependence on inclination, morphological type, and stellar mass. The median growth curve of N2 shows a similar behavior, decreasing from the center toward larger radii. No strong dependence is seen on the inclination, morphological type, and stellar mass. Finally, the median growth curve of O3N2 increases monotonically with radius, and it does not show dependence on the inclination. However, at small radii it shows systematically higher values for galaxies of earlier morphological types and for high stellar mass galaxies. Applying our aperture corrections to a sample of galaxies from the SDSS survey at 0.02 ≤ z ≤ 0.3 shows that the average difference between fiber-based and aperture-corrected oxygen abundances, for different galaxy stellar mass and redshift ranges

  20. Initial Images of the Synthetic Aperture Radiometer 2D-STAR

    Science.gov (United States)

    Initial results obtained using a new synthetic aperture radiometer, 2D-STAR, a dual polarized, L-band radiometer that employs aperture synthesis in two dimensions are presented and analyzed. This airborne instrument is the natural evolution of a previous design that employed employs aperture synthes...

  1. Enhanced transmission of transverse electric waves through periodic arrays of structured subwavelength apertures

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Peng, Liang; Mortensen, Asger

    2010-01-01

    Transmission through sub-wavelength apertures in perfect metals is expected to be strongly suppressed. However, by structural engineering of the apertures, we numerically demonstrate that the transmission of transverse electric waves through periodic arrays of subwavelength apertures in a thin...

  2. Bone and Soft Tissue Ablation

    OpenAIRE

    Foster, Ryan C.B.; Joseph M Stavas

    2014-01-01

    Bone and soft tissue tumor ablation has reached widespread acceptance in the locoregional treatment of various benign and malignant musculoskeletal (MSK) lesions. Many principles of ablation learned elsewhere in the body are easily adapted to the MSK system, particularly the various technical aspects of probe/antenna design, tumoricidal effects, selection of image guidance, and methods to reduce complications. Despite the common use of thermal and chemical ablation procedures in bone and soft...

  3. Imaging of soft tissue tumors.

    OpenAIRE

    Einarsdóttir, Hildur

    2003-01-01

    Abstract The aim of this project on soft tissue tumors, was to evaluate existing imaging methods and test new Magnetic Resonance Imaging (MRI) sequences for diagnosis and assessment of cytotoxic therapy and to relate the imaging studies to cytology to explore the limitations of each procedure. Patients and method The studies were based on patients with a soft tissue lesion diagnosed and treated at the Orthopedic Tumor Service at the Karolinska Hospital 1990-2003. In 17...

  4. Challenges in Soft Tissue Engineering

    OpenAIRE

    Yuksel, Eser; Choo, Joshua; Wettergreen, Matthew; Liebschner, Michael

    2005-01-01

    Soft tissue engineering strategies targeting restoration of volume loss have inherent critical challenges as they relate to the problem of restoration of defects with a high volume to surface ratio. We outline the problems associated with the limitations of translational applications regarding soft tissue engineering strategies as follows: cell survival, mechanical challenges: macroenvironment (scaffold collapse and on-the-shelf availability), compositional considerations: microenvironment, i...

  5. Trabectedin in Soft Tissue Sarcomas

    OpenAIRE

    Petek, Bradley J.; Loggers, Elizabeth T.; Pollack, Seth M.; Jones, Robin L.

    2015-01-01

    Soft tissue sarcomas are a group of rare tumors derived from mesenchymal tissue, accounting for about 1% of adult cancers. There are over 60 different histological subtypes, each with their own unique biological behavior and response to systemic therapy. The outcome for patients with metastatic soft tissue sarcoma is poor with few available systemic treatment options. For decades, the mainstay of management has consisted of doxorubicin with or without ifosfamide. Trabectedin is a synthetic ag...

  6. Soft Skills im bibliothekarischen Berufsalltag

    OpenAIRE

    Brücken, Sandra

    2003-01-01

    Soft Skills, zu deutsch "weiche Fähigkeiten", sind die Kompetenzen, die über fachliche Qualifikationen hinausgehen, wie beispielsweise Teamfähigkeit, Kommunikationstalent und Durchsetzungsvermögen. In dieser Arbeit wird der Frage nachgegangen, inwieweit Soft Skills in der Praxis bibliothekarischer Arbeit Beachtung finden. Über welche Persönlichkeitsmerkmale sollten Bibliothekare verfügen? Wie sieht der Berufsalltag in Bibliotheken heute aus? Welche Tätigkeiten werden vorwiegend ausgeübt? Wie ...

  7. Soft systems, hard lessons.

    Science.gov (United States)

    Kirwan, B

    2000-12-01

    This paper is concerned with practical experiences of achieving human factors and safety interventions in the nuclear power and process control industries. It rests upon the premise that, although human factors (HF) and safety may be technological in approach, they nevertheless must operate in a socio-technical environment, within companies with corporate structures and cultures, interacting with regulatory authorities. A crucial ingredient to the successful implementation and integration of human factors into company practices and procedures is therefore the nature of the inter-relationships between human factors personnel and those who control the existing procedures determining all aspects of the design and operational processes. Such inter-relationships can largely determine whether HF is implemented or not. These human-human interactions and interfaces in a socio-technical system may be referred to as soft systems. When training in human factors, much of the training is concerned with technical aspects of the discipline. However, when entering industry or consultancy, one quickly discovers that technical aspects are usually the least of one's problems. This paper is concerned with experiences and guidance to better help the human factors professional starting out in industry. There is little scientific method in the paper. It is, instead, a distillation of this author's and others' experiences in acting either as a practitioner or consultant, or as leader of a human factors unit in industries that have at times been reluctant or even hostile about the perceived 'invasion' of human factors. However, to avoid being purely anecdotal, the experiences are placed in a framework concerned with the life cycle of integrating human factors into an industry, from being the first HF person in a company, to the development of a successful unit, or the absorption of a successful unit into other departments. Within this framework a range of strategic aspects are dealt with

  8. [Soft tissue rheumatism in erderly].

    Science.gov (United States)

    Szczepański, Leszek

    2008-01-01

    Disorders of soft, peri-articular tissues are a common cause of musculoskeletal pain in elderly patients. Nevertheless, most physicians underestimate the role of soft tissue rheumatism in the pathomechanism of the pain. The impairments of soft tissue can not be diagnosed by X-rays examinations, whereas degenerative lesions of joints are easy diagnosed using this method even despite of their uncertain role in producing the symptoms. The incidence of pain syndromes originated from soft tissues differ regarding to the age of patients. In young subjects the incidence of all of them is generally low. Syndromes provoked by overloading during work: repetitive strain syndrome, canal tunnel syndrome, tennis elbow, golfers elbow, shoulder tendon coin disorders and myofascial pain syndrome are common in middle-aged patients. The morbidity of fibromialgia syndrome is also lower in old people probably as the result of diminished numbers and degenerative changes in nociceptive fibers. The syndromes prevailing in elderly patients include trochanteric syndrome and the pain syndromes provoked by muscle spasm depended on posture abnormalities. In the soft tissue pain syndrome prevention adapted to old age kinesitherapy and avoiding muscle overloading are recommended. Soft tissue pain syndromes are usually treated with non steroidal anti inflammatory drugs. In local pain syndromes better results can be obtained by local treatment. Local injections of glikocorticosteroids are usually very effective and safe.

  9. Materials identification synthetic aperture radar: progress toward a realized capability

    International Nuclear Information System (INIS)

    Most non-metallic materials have frequency-dependent reflectivity functions, that is, they reflect electromagnetic energy in a manner that depends on frequency. Pulsed-chirped synthetic aperture radar and other multispectral radar systems do not generally take into account the frequency dependence of material reflections in forming scenes or making other inferences. In this report, we introduce a simple mathematical approach to using existing pulsed chirp synthetic aperture systems in a manner which results in a determination of a frequency-dependent reflectivity function for each pixel in a computed scene. Our analysis of collected data suggests that the method may be useful to distinguish disturbed from non-disturbed earth, and to detect chemicals on the surface of the earth. The method we have developed provides the analyst with a vector above each pixel with each vector component referencing a frequency band. This additional information may be useful for considering surface texture, subsurface layering and materials identification. (paper)

  10. Reconstruction of defects by ultrasonic testing using synthetic aperture procedures

    International Nuclear Information System (INIS)

    The three methods ALOK (Amplitude Time Locus Curves), PHASED ARRAY and LSAFT (Line-Synthetic-Aperture-Focusing-Technique) use the method of synthesizing a large aperture by moving a probe. All methods are based on the time-of-flight or phase information and less to amplitude information. They differ in the state of development, in the complexity of data acquisition and reconstruction. The ALOK method is closest to those ultrasonic inspection methods used today in inservice inspection of nuclear pressure vessels. PHASED ARRAY combined with the compound scan synthesizes the divergent beam too and insonifies a reflector from many different insonification directions with high energy. LSAFT, like the others, reconstructs a B-scan image. For all three methods examples have been shown which demonstrate the state of development of these systems

  11. Synthetic aperture flow imaging using dual stage beamforming

    DEFF Research Database (Denmark)

    Li, Ye; Jensen, Jørgen Arendt

    2013-01-01

    continuous high frame rate flow images with lower calculation demands than the full synthetic aperture flow imaging. The performance of the approach was investigated using Field II simulations and measurements with the experimental scanner SARUS. A laminar flow with a parabolic profile was generated...... by a flow rig system. The flow data were acquired by a commercial 7 MHz linear array transducer. Four emissions were transmitted sequentially and repeated 12 times corresponding to 48 emissions. Flow with a peak velocity of 0.12 m/s was measured, the relative standard deviation was 6.4%, and the bias was 7......A method for synthetic aperture flow imaging using dual stage beamforming has been developed. The main motivation is to increase the frame rate and still maintain a beamforming quality sufficient for flow estimation that is possible to implement in a commercial scanner. This method can generate...

  12. Study of fractal aperture distribution and flow in fractures

    International Nuclear Information System (INIS)

    This study examines the roughness profiles and aperture distributions of fractures and faults by using concepts from fractal geometry. Simple models of flow of fluid in rough fractures are also discussed. A deterministic fractal representation of the roughness profile is presented which is shown to have many distinct advantages over other numerical methods, such as information compression, uniqueness and repeatability of surface simulation, retention of statistical information, and self-similarity over many scales. Also the fractal representation enables an isotropic surface and an aperture distribution to be simulated by examining a measured profile. Saturated fluid flow in fractures is then computed using a combined Navier-Stokes and Darcy equation. 14 refs., 5 figs

  13. Transmission of Megawatt Relativistic Electron Beams Through Millimeter Apertures

    CERN Document Server

    Alarcon, R; Benson, S V; Bertozzi, W; Boyce, J R; Cowan, R; Douglas, D; Evtushenko, P; Fisher, P; Ihloff, E; Kalantarians, N; Kelleher, A; Legg, R; Milner, R G; Neil, G R; Ou, L; Schmookler, B; Tennant, C; Tschalaer, C; Williams, G P; Zhang, S

    2013-01-01

    High power, relativistic electron beams from energy recovery linacs have great potential to realize new experimental paradigms for pioneering innovation in fundamental and applied research. A major design consideration for this new generation of experimental capabilities is the understanding of the halo associated with these bright, intense beams. In this Letter, we report on measurements performed using the 100 MeV, 430 kWatt CW electron beam from the energy recovery linac at the Jefferson Laboratory's Free Electron Laser facility as it traversed a set of small apertures in a 127 mm long aluminum block. Thermal measurements of the block together with neutron measurements near the beam-target interaction point yielded a consistent understanding of the beam losses. These were determined to be 3 ppm through a 2 mm diameter aperture and were maintained during a 7 hour continuous run.

  14. Apodized vortex coronagraph designs for segmented aperture telescopes

    CERN Document Server

    Ruane, Garreth; Mawet, Dimitri; Pueyo, Laurent; Shaklan, Stuart

    2016-01-01

    Current state-of-the-art high contrast imaging instruments take advantage of a number of elegant coronagraph designs to suppress starlight and image nearby faint objects, such as exoplanets and circumstellar disks. The ideal performance and complexity of the optical systems depends strongly on the shape of the telescope aperture. Unfortunately, large primary mirrors tend to be segmented and have various obstructions, which limit the performance of most conventional coronagraph designs. We present a new family of vortex coronagraphs with numerically-optimized gray-scale apodizers that provide the sensitivity needed to directly image faint exoplanets with large, segmented aperture telescopes, including the Thirty Meter Telescope (TMT) as well as potential next-generation space telescopes.

  15. Wide Aperture Vector magnet for neutron scattering studies

    CERN Document Server

    Lavie, P; Peugeot, A; Bredy, P; Berriaud, C; Daël, A; Riffet, J -M; Klimko, S; Meuriot, J -L; Robillard, T; Aubert, G

    2016-01-01

    We propose an innovative design for a vector magnet compatible with neutron scattering experiments. This would vastly expand the range of experimental possibilities since applying a magnetic field and orienting the sample in diffraction conditions will become completely independent. This Wide Aperture VEctor magnet is a setup made of 16 coils, all with a vertical axis. The vertical component of the field is produced by two pairs of coaxial coils carrying opposite currents for an active shielding of the stray field, while the horizontal components are generated by 3 sets of 4 coils each, two above and two below the diffraction plane. This innovative geometry allows a very wide aperture (220$\\,^{\\circ}$ horizontal, $\\pm$ 10$\\,^{\\circ}$ vertical), which is crucial for neutron diffraction and inelastic neutron scattering experiments. Moreover, the homogeneity of the field is far better than in the usual vertical coils, and the diameter of the sample bore is unusually large (10 cm). The concept has been developed ...

  16. Implementation of real-time duplex synthetic aperture ultrasonography

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Larsen, Lee; Kjeldsen, Thomas;

    2015-01-01

    in the TCP/IP protocol. Benchmarking of real-time imaging showed a total processing time of 25.7 ms (39 frames/s) which is less than the acquisition time (29.4 ms). In conclusion, the proposed implementation demonstrates that both B-mode and CFM can be executed in-time for real-time ultrasound imaging......This paper presents a real-time duplex synthetic aperture imaging system, implemented on a commercially available tablet. This includes real-time wireless reception of ultrasound signals and GPU processing for B-mode and Color Flow Imaging (CFM). The objective of the work is to investigate...... the implementation complexity and processing demands. The image processing is performed using the principle of Synthetic Aperture Sequential Beamforming (SASB) and the flow estimator is implemented using the cross-correlation estimator. Results are evaluated using a HTC Nexus 9 tablet and a BK Medical BK3000...

  17. Adaptive Matching of the Scanning Aperture of the Environment Parameter

    Science.gov (United States)

    Choni, Yu. I.; Yunusov, N. N.

    2016-04-01

    We analyze a matching system for the scanning aperture antenna radiating through a layer with unpredictably changing parameters. Improved matching has been achieved by adaptive motion of a dielectric plate in the gap between the aperture and the radome. The system is described within the framework of an infinite layered structure. The validity of the model has been confirmed by numerical simulation using CST Microwave Studio software and by an experiment. It is shown that the reflection coefficient at the input of some types of a matching device, which is due to the deviation of the load impedance from the nominal value, is determined by a compact and versatile formula. The potential efficiency of the proposed matching system is shown by a specific example, and its dependence on the choice of the starting position of the dielectric plate is demonstrated.

  18. Soft robotics: a bioinspired evolution in robotics.

    Science.gov (United States)

    Kim, Sangbae; Laschi, Cecilia; Trimmer, Barry

    2013-05-01

    Animals exploit soft structures to move effectively in complex natural environments. These capabilities have inspired robotic engineers to incorporate soft technologies into their designs. The goal is to endow robots with new, bioinspired capabilities that permit adaptive, flexible interactions with unpredictable environments. Here, we review emerging soft-bodied robotic systems, and in particular recent developments inspired by soft-bodied animals. Incorporating soft technologies can potentially reduce the mechanical and algorithmic complexity involved in robot design. Incorporating soft technologies will also expedite the evolution of robots that can safely interact with humans and natural environments. Finally, soft robotics technology can be combined with tissue engineering to create hybrid systems for medical applications.

  19. An Algebraic Approach to Synthetic Aperture Sonar Image Reconstruction

    OpenAIRE

    Sergio Rui Silva; Sergio Cunha; Anibal Matos; Nuno Cruz

    2008-01-01

    A new approach for synthetic aperture image formation is presented in this paper. With the presented method image formation is regarded as a signal arrangement that can be described by a matrix. This method integrates the sonar platform motion in the image formation process but more importantly it acknowledges the non ideal data gathering process and implements means to mitigate these shortcomings. This method is illustrated with real data obtained in test mission in the Douro River, Portugal...

  20. Application of Linear Prediction Technique to Passive Synthetic Aperture Processing

    OpenAIRE

    Hou Yunshan; Huang Jianguo; Jiang Min; Jin Yong

    2010-01-01

    A method for the synthesis of an aperture with improved angular resolution and array gain is described. The proposed method explores the merit of linear prediction technique to improve the performance of conventional ETAM (extended towed array measurements) method. Previous efforts to improve the ETAM method generally focused on how to get more accurate estimation of overlap correlator, with an aim to reduce bearing estimation variance. In this paper, however, we discuss how to further impro...

  1. Digital Beamforming Synthetic Aperture Radar (DBSAR) Polarimetric Upgrade

    Science.gov (United States)

    Rincon, Rafael F.; Perrine, Martin; McLinden, Matthew; Valett, Susan

    2011-01-01

    The Digital Beamforming Synthetic Aperture Radar (DBSAR) is a state-of-the-art radar system developed at NASA/Goddard Space Flight Center for the development and implementation of digital beamforming radar techniques. DBSAR was recently upgraded to polarimetric operation in order to enhance its capability as a science instrument. Two polarimetric approaches were carried out which will be demonstrated in upcoming flight campaigns.

  2. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging

    OpenAIRE

    Shuanghui Zhang; Yongxiang Liu; Xiang Li; Guoan Bi

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed met...

  3. Seamless Synthetic Aperture Radar Archive for Interferometry Analysis

    OpenAIRE

    S. Baker; C. Baru; Bryson, G; Buechler, B.; Crosby, C.; Fielding, E.; Meertens, C.; Nicoll, J.; Youn, C.

    2014-01-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived interferometric SAR (InSAR) data products. A unified application programming interface...

  4. Dynamic aperture studies for the LHC high luminosity lattice

    Energy Technology Data Exchange (ETDEWEB)

    Maria, R. de [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Giovannozzi, M. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); McIntosh, E. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Nosochkov, Y. M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Cai, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Wang, M. -H. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-07-14

    Since quite some time, dynamic aperture studies have been undertaken with the aim of specifying the required field quality of the new magnets that will be installed in the LHC ring in the framework of the high-luminosity upgrade. In this paper the latest results concerning the specification work will be presented, taking into account both injection and collision energies and the field quality contribution from all the magnets in the newly designed interaction regions.

  5. Inverse synthetic aperture radar imaging principles, algorithms and applications

    CERN Document Server

    Chen , Victor C

    2014-01-01

    Inverse Synthetic Aperture Radar Imaging: Principles, Algorithms and Applications is based on the latest research on ISAR imaging of moving targets and non-cooperative target recognition (NCTR). With a focus on the advances and applications, this book will provide readers with a working knowledge on various algorithms of ISAR imaging of targets and implementation with MATLAB. These MATLAB algorithms will prove useful in order to visualize and manipulate some simulated ISAR images.

  6. Imaging of Airborne Synthetic Aperture Ladar under Platform Vibration Condition

    OpenAIRE

    Ma Meng; Li Dao-jing; Du Jian-bo

    2014-01-01

    This study examines the imaging problems in airborne synthetic aperture ladar with single detector and dual detectors along tracks under platform vibration condition. Because platform vibrations affect imaging processing for short intervals negligibly, a method uniting the subaperture imaging and phase gradient autofocus is considered for single-detector ladar. To obtain long stripmap images in azimuth, the stripmap phase gradient autofocus method and the subaperture image mosaic process usin...

  7. Two-Dimensional Aperture Coding for Magnetic Sector Mass Spectrometry

    Science.gov (United States)

    Russell, Zachary E.; Chen, Evan X.; Amsden, Jason J.; Wolter, Scott D.; Danell, Ryan M.; Parker, Charles B.; Stoner, Brian R.; Gehm, Michael E.; Brady, David J.; Glass, Jeffrey T.

    2015-02-01

    In mass spectrometer design, there has been a historic belief that there exists a fundamental trade-off between instrument size, throughput, and resolution. When miniaturizing a traditional system, performance loss in either resolution or throughput would be expected. However, in optical spectroscopy, both one-dimensional (1D) and two-dimensional (2D) aperture coding have been used for many years to break a similar trade-off. To provide a viable path to miniaturization for harsh environment field applications, we are investigating similar concepts in sector mass spectrometry. Recently, we demonstrated the viability of 1D aperture coding and here we provide a first investigation of 2D coding. In coded optical spectroscopy, 2D coding is preferred because of increased measurement diversity for improved conditioning and robustness of the result. To investigate its viability in mass spectrometry, analytes of argon, acetone, and ethanol were detected using a custom 90-degree magnetic sector mass spectrometer incorporating 2D coded apertures. We developed a mathematical forward model and reconstruction algorithm to successfully reconstruct the mass spectra from the 2D spatially coded ion positions. This 2D coding enabled a 3.5× throughput increase with minimal decrease in resolution. Several challenges were overcome in the mass spectrometer design to enable this coding, including the need for large uniform ion flux, a wide gap magnetic sector that maintains field uniformity, and a high resolution 2D detection system for ion imaging. Furthermore, micro-fabricated 2D coded apertures incorporating support structures were developed to provide a viable design that allowed ion transmission through the open elements of the code.

  8. Nonlinear ocean internal waves observed by multifrequency synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    YANG Jingsong; XIAO Qingmei; HUANG Weigen; FU Bin; CHEN Peng

    2008-01-01

    A numerical model which consists of the Korteweg-de Vries (KdV) equation, the action balance equation and the radar backscat- tering model is developed to simulate the frequency dependence of synthetic aperture radar (SAR) remote sensing of nonlinear o- cean internal waves. Muhifrequency data collected by NASA SIR - C SAR and NASA JPL AIRSAR are used as comparison. Case studies show that the results of simulation agree well with the results of SAR data.

  9. Dynamic Aperture Studies for the FCC-ee

    CERN Document Server

    Medina, L; Tomas, R; Zimmermann, F

    2015-01-01

    Dynamic aperture (DA) studies have been conducted on the latest Future Circular Collider – ee (FCC-ee) lattices as a function of momentum deviation.Two different schemes for the interaction region are used, which are connected to the main arcs: the crab waist approach, developed by BINP, and an update to the CERN design where the use of crab cavities is envisioned. The results presented show an improvement in the performance of both designs.

  10. Two-dimensional aperture coding for magnetic sector mass spectrometry.

    Science.gov (United States)

    Russell, Zachary E; Chen, Evan X; Amsden, Jason J; Wolter, Scott D; Danell, Ryan M; Parker, Charles B; Stoner, Brian R; Gehm, Michael E; Brady, David J; Glass, Jeffrey T

    2015-02-01

    In mass spectrometer design, there has been a historic belief that there exists a fundamental trade-off between instrument size, throughput, and resolution. When miniaturizing a traditional system, performance loss in either resolution or throughput would be expected. However, in optical spectroscopy, both one-dimensional (1D) and two-dimensional (2D) aperture coding have been used for many years to break a similar trade-off. To provide a viable path to miniaturization for harsh environment field applications, we are investigating similar concepts in sector mass spectrometry. Recently, we demonstrated the viability of 1D aperture coding and here we provide a first investigation of 2D coding. In coded optical spectroscopy, 2D coding is preferred because of increased measurement diversity for improved conditioning and robustness of the result. To investigate its viability in mass spectrometry, analytes of argon, acetone, and ethanol were detected using a custom 90-degree magnetic sector mass spectrometer incorporating 2D coded apertures. We developed a mathematical forward model and reconstruction algorithm to successfully reconstruct the mass spectra from the 2D spatially coded ion positions. This 2D coding enabled a 3.5× throughput increase with minimal decrease in resolution. Several challenges were overcome in the mass spectrometer design to enable this coding, including the need for large uniform ion flux, a wide gap magnetic sector that maintains field uniformity, and a high resolution 2D detection system for ion imaging. Furthermore, micro-fabricated 2D coded apertures incorporating support structures were developed to provide a viable design that allowed ion transmission through the open elements of the code. PMID:25510933

  11. Dirichlet eigenvalues of cones in the small aperture limit

    OpenAIRE

    Ourmières-Bonafos, Thomas

    2014-01-01

    We are interested in finite cones of fixed height 1 parametrized by their opening angle. We study the eigenpairs of the Dirichlet Laplacian in such domains when their apertures tend to 0. We provide multi-scale asymptotics for eigenpairs associated with the lowest eigenvalues of each fiber of the Dirichlet Laplacian. In order to do this, we investigate the family of their one-dimensional Born-Oppenheimer approximations. The eigenvalue asymptotics involves powers of the cube root of the apertu...

  12. Synthetic Aperture Sonar Imaging via One-Way Wave Equations

    CERN Document Server

    Huynh, Quyen

    2009-01-01

    We develop an efficient algorithm for Synthetic Aperture Sonar imaging based on the one-way wave equations. The algorithm utilizes the operator-splitting method to integrate the one-way wave equations. The well-posedness of the one-way wave equations and the proposed algorithm is shown. A computational result against real field data is reported and the resulting image is enhanced by the BV-like regularization.

  13. Range-instantaneous Doppler imaging of inverse synthetic aperture sonar

    Institute of Scientific and Technical Information of China (English)

    XU Jia; JIANG Xingzhou; TANG Jingsong

    2003-01-01

    Because the existing range-Doppler algorithm in inverse synthetic aperture sonar (ISAS) is based on target model of uniform motion, it may be invalidated for maneuvering targets due to the time-varying changes of both individual scatter′s Doppler and imaging projection plane. To resolve the problem, a new range-instantaneous Doppler imaging method is proposed for imaging maneuvering targets based on time-frequency analysis. The proposed approach is verified using real underwater acoustic data.

  14. Wide Aperture Vector magnet for neutron scattering studies

    OpenAIRE

    LAVIE, P.; Bataille, A. M.; Peugeot, A.; Bredy, P.; Berriaud, C.; Daël, A.; Riffet, J. -M.; Klimko, S.; Meuriot, J. -L.; Robillard, T.; Aubert, G.

    2016-01-01

    We propose an innovative design for a vector magnet compatible with neutron scattering experiments. This would vastly expand the range of experimental possibilities since applying a magnetic field and orienting the sample in diffraction conditions will become completely independent. This Wide Aperture VEctor magnet is a setup made of 16 coils, all with a vertical axis. The vertical component of the field is produced by two pairs of coaxial coils carrying opposite currents for an active shield...

  15. Limits to Clutter Cancellation in Multi-Aperture GMTI Data

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Multi-aperture or multi-subaperture antennas are fundamental to Ground Moving Target Indicator (GMTI) radar systems in order to detect slow-moving targets with Doppler characteristics similar to clutter. Herein we examine the performance of several subaperture architectures for their clutter cancelling performance. Significantly, more antenna phase centers isn’t always better, and in fact is sometimes worse, for detecting targets.

  16. Aperture synthesis concepts in microwave remote sensing of the earth

    Science.gov (United States)

    Swift, Calvin T.; Le Vine, David M.; Ruf, Christopher S.

    1991-01-01

    The application of aperture synthesis concepts, used for many years in radio astronomy to achieve high image resolution at a reasonable cost, to remote sensing technology is discussed. The electronically scanned thinned array radiometer (ESTAR) is put forward as a viable alternative to improve spatial resolution by an order of magnitude over what is presently achieved by microwave imaging systems that are collecting data from earth orbit. Future developments in airborne sensor technology and potential spacecraft application are described.

  17. Passive Interferometric Ocean Currents Observation Synthetic Aperture Radar (PICOSAR)

    OpenAIRE

    Börner, Thomas; López-Dekker, Paco; Krieger, Gerhard; Bachmann, Markus; Moreira, Alberto; Müller, Hartmut

    2014-01-01

    This chapter describes PICOSAR (Passive Interferometric Ocean Currents Observation Synthetic Aperture Radar), a concept consisting of two small, low-cost and low power spacecraft carrying a passive, receive-only SAR payload. PICOSAR enhances the functionality of a full SAR system such as Sentinel-1 or TerraSAR-X by adding a unique along-track interferometer dedicated to ocean surface current measurements. The passive nature of this system and the focus on a single application and single opera...

  18. Soft Mobility and Urban Transformation

    Directory of Open Access Journals (Sweden)

    Rosa Anna La Rocca

    2010-04-01

    Full Text Available This paper examines some European cases referred to promotion of soft mobility as a new lifestyle aimed to improve benefits on environment and urban liveability. Soft mobility includes any non-motorized transport (human powered mobility. According to this, soft mobility refers to pedestrian, bicycle, roller skate and skateboard transfers. It could be indented as “zeroimpact” mobility too. As a matter of fact, the words to define this way of moving have not been codified yet, therefore mobilitè douce, soft mobility, slow traffic are synonymous in referring mainly to pedestrians and cyclists to indicate alternative to car use. Soft mobility, indeed, can be defined as a special form of sustainable mobility able to optimize urban liveability, by keeping the individual right to move. At present, cities are engaged in defining policies, procedures and interventions to further “slow traffic”, both to relieve the traffic congestion, and to work for regeneration and environmental improvements. This asks for an in-depth cooperation between different political and administrative levels to achieve common objectives of development more attentive to environmental concerns. Despite this increasing attention, the idea of a “network” for soft mobility has not been yet achieved and the supply of integrated facilities and services as an alternative to the car use seems to be still difficult of accomplishment. High disparity characterizes European countries in promoting soft mobility: despite a prolific production of laws and roles referred to emergency of adopting alternative ways of moving to minimize negatives impacts (especially air and noise pollution as very threat to health due to car dependence for urban short distance too. And yet, soft mobility could represent a real occasion of urban and territorial regeneration aimed to rehabilitate some disused paths and routes (greenways. Some successful European cases show how it is possible to

  19. Asynchronous rotation scan for synthetic aperture interferometric radiometer

    Institute of Scientific and Technical Information of China (English)

    WU Ji; ZHANG Cheng; LIU Hao; SUN WeiYing

    2009-01-01

    Synthetic aperture interferometric technique has wide applications in optics, radio astronomy and mi-crowave remote sensing areas. With the increasing demands of high resolution imaging observation, a new time-sharing sampling scheme of asynchronous rotation scan is proposed to meet the technical challenge of achieving a large equivalent aperture and overcome the operating barriers of space borne application. This configuration is basically composed by two asynchronously and concentrically ro-tating antenna groups, whose revolving radii and speeds are different. The synthetic aperture system with asynchronous rotation scanning scheme can effectively solve the trade-off problem of system complexity, and greatly simplify the system hardware at the cost of sacrificing a certain time resolution. The basic rules and design methods of asynchronous rotation scan are investigated The Gridding method is introduced to inverse the spiral sampling data for image reconstruction. The potential ap-plications of geostationary orbit (GEO) earth observation and solar polar orbit (SPO) plasma cloud observation are explored with numerical simulations to validate the significance and feasibility of this new imaging configuration.

  20. Lyot coronagraph design study for large, segmented space telescope apertures

    Science.gov (United States)

    Zimmerman, Neil T.; N'Diaye, Mamadou; St. Laurent, Kathryn E.; Soummer, Rémi; Pueyo, Laurent; Stark, Christopher C.; Sivaramakrishnan, Anand; Perrin, Marshall; Vanderbei, Robert J.; Kasdin, N. J.; Shaklan, Stuart; Carlotti, Alexis

    2016-07-01

    Recent efforts combining the optimization techniques of apodized pupil Lyot coronagraphs (APLC) and shaped pupils have demonstrated the viability of a binary-transmission mask architecture for extremely high contrast (10-10) exoplanet imaging. We are now building on those innovations to carry out a survey of Lyot coronagraph performance for large, segmented telescope apertures. These apertures are of the same kind under considera- tion for NASA's Large UV/Optical/IR (LUVOIR) observatory concept. To map the multi-dimensional design parameter space, we have developed a software toolkit to manage large sets of mask optimization programs and execute them on a computing cluster. Here we summarize a preliminary survey of 500 APLC solutions for 4 reference hexagonal telescope apertures. Several promising designs produce annular, 10-10 contrast dark zones down to inner working angle 4λ0=D over a 15% bandpass, while delivering a half-max PSF core throughput of 18%. We also report our progress on devising solutions to the challenges of Lyot stop alignment/fabrication tolerance that arise in this contrast regime.

  1. Optimized baffle and aperture placement in neutral beamlines

    International Nuclear Information System (INIS)

    Most neutral beamlines contain an iron-core ion-bending magnet that requires shielding between the end of the neutralizer and this magnet. This shielding allows the gas pressure to drop prior to the beam entering the magnet and therefore reduces beam losses in this drift region. We have found that the beam losses can be reduced even further by eliminating the iron-core magnet and the magnetic shielding altogether. The required bending field can be supplied by current coils without the iron poles. In addition, placement of the baffles and apertures can affect the cold gas entering the plasma region and the losses in the neutral beam due to re-ionization. In our study we varied the placement of the baffles, which determine the amount of pumping in each chamber, and the apertures, which determine the beam loss. Our results indicate that a baffle/aperture configuration can be set for either minimum cold gas into the plasma region or minimum beam losses, but not both

  2. Aperture effects on the oxygen abundance determinations from CALIFA data

    CERN Document Server

    Iglesias-Páramo, J; Rosales-Ortega, F F; Sánchez, S F; Puertas, S Duarte; Petropoulou, V; de Paz, A Gil; Galbany, L; Mollá, M; Catalán-Torrecilla, C; Morales, A Castillo; Mast, D; Husemann, B; García-Benito, R; Mendoza, M A; Kehrig, C; Pérez-Montero, E; Papaderos, P; Gomes, J M; Walcher, C J; Delgado, R M González; Marino, R A; López-Sánchez, Á R; Ziegler, B; Flores, H; Alves, J

    2016-01-01

    This paper aims at providing aperture corrections for emission lines in a sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey (CALIFA) database. In particular, we explore the behavior of the log([OIII]5007/Hbeta)/([NII]6583/Halpha) (O3N2) and log[NII]6583/Halpha (N2) flux ratios since they are closely connected to different empirical calibrations of the oxygen abundances in star forming galaxies. We compute median growth curves of Halpha, Halpha/Hbeta, O3N2 and N2 up to 2.5R_50 and 1.5 disk R_eff. The growth curves simulate the effect of observing galaxies through apertures of varying radii. The median growth curve of the Halpha/Hbeta ratio monotonically decreases from the center towards larger radii, showing for small apertures a maximum value of ~10% larger than the integrated one. The median growth curve of N2 shows a similar behavior, decreasing from the center towards larger radii. No strong dependence is seen with the inclination, morphological type and stellar mass for these...

  3. Colored coded-apertures for spectral image unmixing

    Science.gov (United States)

    Vargas, Hector M.; Arguello Fuentes, Henry

    2015-10-01

    Hyperspectral remote sensing technology provides detailed spectral information from every pixel in an image. Due to the low spatial resolution of hyperspectral image sensors, and the presence of multiple materials in a scene, each pixel can contain more than one spectral signature. Therefore, endmember extraction is used to determine the pure spectral signature of the mixed materials and its corresponding abundance map in a remotely sensed hyperspectral scene. Advanced endmember extraction algorithms have been proposed to solve this linear problem called spectral unmixing. However, such techniques require the acquisition of the complete hyperspectral data cube to perform the unmixing procedure. Researchers show that using colored coded-apertures improve the quality of reconstruction in compressive spectral imaging (CSI) systems under compressive sensing theory (CS). This work aims at developing a compressive supervised spectral unmixing scheme to estimate the endmembers and the abundance map from compressive measurements. The compressive measurements are acquired by using colored coded-apertures in a compressive spectral imaging system. Then a numerical procedure estimates the sparse vector representation in a 3D dictionary by solving a constrained sparse optimization problem. The 3D dictionary is formed by a 2-D wavelet basis and a known endmembers spectral library, where the Wavelet basis is used to exploit the spatial information. The colored coded-apertures are designed such that the sensing matrix satisfies the restricted isometry property with high probability. Simulations show that the proposed scheme attains comparable results to the full data cube unmixing technique, but using fewer measurements.

  4. Microstrip Yagi Antenna with Dual Aperture-Coupled Feed

    Science.gov (United States)

    Pogorzelski, Ronald; Venkatesan, Jaikrishna

    2008-01-01

    A proposed microstrip Yagi antenna would operate at a frequency of 8.4 GHz (which is in the X band) and would feature a mechanically simpler, more elegant design, relative to a prior L-band microstrip Yagi antenna. In general, the purpose of designing a microstrip Yagi antenna is to combine features of a Yagi antenna with those of a microstrip patch to obtain an antenna that can be manufactured at low cost, has a low profile, and radiates a directive beam that, as plotted on an elevation plane perpendicular to the antenna plane, appears tilted away from the broadside. Such antennas are suitable for flush mounting on surfaces of diverse objects, including spacecraft, aircraft, land vehicles, and computers. Stated somewhat more precisely, what has been proposed is a microstrip antenna comprising an array of three Yagi elements. Each element would include four microstrip-patch Yagi subelements: one reflector patch, one driven patch, and two director patches. To obtain circular polarization, each driven patch would be fed by use of a dual offset aperture-coupled feed featuring bow-tie-shaped apertures. The selection of the dual offset bow-tie aperture geometry is supported by results found in published literature that show that this geometry would enable matching of the impedances of the driven patches to the 50-Omega impedance of the microstrip feedline while maintaining a desirably large front-to-back lobe ratio.

  5. Coronagraph-integrated wavefront sensing with a sparse aperture mask

    Science.gov (United States)

    Subedi, Hari; Zimmerman, Neil T.; Kasdin, N. Jeremy; Cavanagh, Kathleen; Riggs, A. J. Eldorado

    2015-07-01

    Stellar coronagraph performance is highly sensitive to optical aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph, such as tip-tilt, defocus, and coma, must be determined and compensated. Previous authors have established the utility of pupil-plane masks (both nonredundant/sparse-aperture and generally asymmetric aperture masks) for wavefront sensing (WFS). Here, we show how a sparse aperture mask (SAM) can be integrated with a coronagraph to measure low-order differential phase aberrations. Starlight rejected by the coronagraph's focal plane stop is collimated to a relay pupil, where the mask forms an interference fringe pattern on a subsequent detector. Our numerical Fourier propagation models show that the information encoded in the fringe intensity distortions is sufficient to accurately discriminate and estimate Zernike phase modes extending from tip-tilt up to radial degree n=5, with amplitude up to λ/20 RMS. The SAM sensor can be integrated with both Lyot and shaped pupil coronagraphs at no detriment to the science beam quality. We characterize the reconstruction accuracy and the performance under low flux/short exposure time conditions, and place it in context of other coronagraph WFS schemes.

  6. Asynchronous rotation scan for synthetic aperture interferometric radiometer

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Synthetic aperture interferometric technique has wide applications in optics,radio astronomy and mi-crowave remote sensing areas.With the increasing demands of high resolution imaging observation,a new time-sharing sampling scheme of asynchronous rotation scan is proposed to meet the technical challenge of achieving a large equivalent aperture and overcome the operating barriers of space borne application.This configuration is basically composed by two asynchronously and concentrically ro-tating antenna groups,whose revolving radii and speeds are different.The synthetic aperture system with asynchronous rotation scanning scheme can effectively solve the trade-off problem of system complexity,and greatly simplify the system hardware at the cost of sacrificing a certain time resolution.The basic rules and design methods of asynchronous rotation scan are investigated The Gridding method is introduced to inverse the spiral sampling data for image reconstruction.The potential ap-plications of geostationary orbit(GEO)earth observation and solar polar orbit(SPO)plasma cloud observation are explored with numerical simulations to validate the significance and feasibility of this new imaging configuration.

  7. Phase contrast microscopy with full numerical aperture illumination.

    Science.gov (United States)

    Maurer, Christian; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2008-11-24

    A modification of the phase contrast method in microscopy is presented, which reduces inherent artifacts and improves the spatial resolution. In standard Zernike phase contrast microscopy the illumination is achieved through an annular ring aperture, and the phase filtering operation is performed by a corresponding phase ring in the back focal plane of the objective. The Zernike method increases the spatial resolution as compared to plane wave illumination, but it also produces artifacts, such as the halo- and the shade-off effect. Our modification consists in replacing the illumination ring by a set of point apertures which are randomly distributed over the whole aperture of the condenser, and in replacing the Zernike phase ring by a matched set of point-like phase shifters in the back focal plane of the objective. Experimentally this is done by illuminating the sample with light diffracted from a phase hologram displayed at a spatial light modulator (SLM). The subsequent filtering operation is then done with a second matched phase hologram displayed at another SLM in a Fourier plane of the imaging pathway. This method significantly reduces the halo- and shade-off artifacts whilst providing the full spatial resolution of the microscope. PMID:19030068

  8. Radio Astronomy transformed: Aperture Arrays - Past, Present and Future

    CERN Document Server

    Garrett, M A

    2013-01-01

    Aperture Arrays have played a major role in radio astronomy since the field emerged from the results of long-distance communication tests performed by Karl Jansky in the early 1930's. The roots of this technology extend back beyond Marconi, although the first electronically scanned instrument only appeared in the run-up to World War II. After the war, phased arrays had a major impact in many walks of life, including astronomy and astrophysics. Major progress was made in understanding the nature of the radio sky, including the discovery of Pulsars. Despite these early successes, parabolic dishes largely replaced aperture arrays through the 1960's, and right up until the end of the 20th century. Technological advances in areas such as signal processing, digital electronics, low-power/high performance super-computing and large capacity data storage systems have recently led to a substantial revival in the use of aperture arrays - especially at frequencies below 300 MHz. Composed of simple antennas with commercia...

  9. Strategies and performances of Soft Input Decryption

    OpenAIRE

    Zivic, Natasa

    2009-01-01

    This paper analyzes performance aspects of Soft Input Decryption and L values. Soft Input Decryption is a novel method which uses L values (soft output) of a SISO channel decoder for the correction of input of Soft Input Decryption (SID blocks) which have been modified during the transmission over a noisy channel. The method is based on the combination of cryptography and channel coding improving characteristics of both of them. The algorithm, strategies and scenarios of Soft Input Decryption...

  10. Synthetic Aperture Radiometry Evaluated by a Two-Channel Demonstration Model

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1998-01-01

    radiometer systems, especially at low frequencies. The TUD SARad demonstration model consists of a two-channel Ku-band correlation radiometer with two horn antennas and an antenna mounting structure enabling the horns to be mounted in relevant positions within a certain aperture. A total aperture synthesis......The Technical University of Denmark (TUD) Synthetic Aperture Radiometer (SARad) is a two-channel demonstration model that can simulate a two-dimensional (2D) thinned array radiometer having an unfilled aperture populated with several small antenna elements. Aperture synthesis obtained by...

  11. Microfluidic magnetic separator using an array of soft magnetic elements

    DEFF Research Database (Denmark)

    Smistrup, Kristian; Lund-Olesen, Torsten; Hansen, Mikkel Fougt;

    2006-01-01

    We present the design, fabrication, characterization, and demonstration of a new passive magnetic bead separator. The device operates in an effective state when magnetized by an external magnetic field of only 50 mT, which is available from a tabletop electromagnet. We demonstrate the complete...

  12. Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

    Science.gov (United States)

    Dönsberg, Timo; Mäntynen, Henrik; Ikonen, Erkki

    2016-06-01

    The measurement uncertainty of illuminance and, consequently, luminous flux and luminous efficacy of LED lamps can be reduced with a recently introduced method based on the predictable quantum efficient detector (PQED). One of the most critical factors affecting the measurement uncertainty with the PQED method is the determination of the aperture area. This paper describes an upgrade to an optical method for direct determination of aperture area where superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by scanning the aperture in front of an intensity-stabilized laser beam. In the upgraded method, the aperture is attached to the PQED and the whole package is transversely scanned relative to the laser beam. This has the benefit of having identical geometry in the laser scanning of the aperture area and in the actual photometric measurement. Further, the aperture and detector assembly does not have to be dismantled for the aperture calibration. However, due to small acceptance angle of the PQED, differences between the diffraction effects of an overfilling plane wave and of a combination of Gaussian laser beams at the circular aperture need to be taken into account. A numerical calculation method for studying these effects is discussed in this paper. The calculation utilizes the Rayleigh-Sommerfeld diffraction integral, which is applied to the geometry of the PQED and the aperture. Calculation results for various aperture diameters and two different aperture-to-detector distances are presented.

  13. Calculation Method and Distribution Characteristics of Fracture Hydraulic Aperture from Field Experiments in Fractured Granite Area

    Science.gov (United States)

    Cao, Yang-Bing; Feng, Xia-Ting; Yan, E.-Chuan; Chen, Gang; Lü, Fei-fei; Ji, Hui-bin; Song, Kuang-Yin

    2016-05-01

    Knowledge of the fracture hydraulic aperture and its relation to the mechanical aperture and normal stress is urgently needed in engineering construction and analytical research at the engineering field scale. A new method based on the in situ borehole camera measurement and borehole water-pressure test is proposed for the calculation of the fracture hydraulic aperture. This method comprises six steps. The first step is to obtain the equivalent hydraulic conductivity of the test section from borehole water-pressure tests. The second step is a tentative calculation to obtain the qualitative relation between the reduction coefficient and the mechanical aperture obtained from borehole camera measurements. The third step is to choose the preliminary reduction coefficient for obtaining the initial hydraulic aperture. The remaining three steps are to optimize, using the genetic algorithm, the hydraulic apertures of fractures with high uncertainty. The method is then applied to a fractured granite engineering area whose purpose is the construction of an underground water-sealed storage cavern for liquefied petroleum gas. The probability distribution characteristics of the hydraulic aperture, the relationship between the hydraulic aperture and the mechanical aperture, the hydraulic aperture and the normal stress, and the differences between altered fractures and fresh fractures are all analyzed. Based on the effects of the engineering applications, the method is proved to be feasible and reliable. More importantly, the results of the hydraulic aperture obtained in this paper are different from those results elicited from laboratory tests, and the reasons are discussed in the paper.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  15. Soft nanotechnology: "structure" vs. "function".

    Science.gov (United States)

    Whitesides, George M; Lipomi, Darren J

    2009-01-01

    This paper offers a perspective on "soft nanotechnology"; that is, the branch of nanotechnology concerned with the synthesis and properties of organic and organometallic nanostructures, and with nanofabrication using techniques in which soft components play key roles. It begins with a brief history of soft nanotechnology. This history has followed a path involving a gradual shift from the promise of revolutionary electronics, nanorobotics, and other futuristic concepts, to the realization of evolutionary improvements in the technology for current challenges in information technology, medicine, and sustainability. Soft nanoscience is an area that is occupied principally by chemists, and is in many ways indistinguishable from "nanochemistry". The paper identifies the natural tendency of its practitioners--exemplified by the speakers at this Faraday Discussion--to focus on synthesis and structure, rather than on function and application, of nanostructures. Soft nanotechnology has the potential to apply to a wide variety of large-scale applied (information technology, healthcare cost reduction, sustainability, energy) and fundamental (molecular biochemistry, cell biology, charge transport in organic matter) problems.

  16. Hard-soft composite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ghidini, M. [Department of Physics, University of Parma and CNISM, V.le G.P. Usberti 7/A, 43100, Parma (Italy)]. E-mail: ghidini@fis.unipr.it; Asti, G. [Department of Physics, University of Parma and CNISM, V.le G.P. Usberti 7/A, 43100, Parma (Italy); Pellicelli, R. [Department of Physics, University of Parma and CNISM, V.le G.P. Usberti 7/A, 43100, Parma (Italy); Pernechele, C. [Department of Physics, University of Parma and CNISM, V.le G.P. Usberti 7/A, 43100, Parma (Italy); Solzi, M. [Department of Physics, University of Parma and CNISM, V.le G.P. Usberti 7/A, 43100, Parma (Italy)

    2007-09-15

    A thorough micromagnetic analysis of the exchange-spring problem is reported with special emphasis on multilayers constituted by hard-soft exchange-coupled phases. The developed one-dimensional micromagnetic model leads to a complete magnetic phase diagram in terms of layer thicknesses. Both perpendicular and parallel configurations are considered. The phase diagram provides information on the type of demagnetization processes and the critical fields at which nucleation and reversal take place, depending on the intrinsic properties of the chosen soft and hard materials. The model has been applied to a variety of hard magnetic phases (e.g., FePt, CoPt, SmCo and NdFeB), coupled to different soft materials (e.g., Fe, FeCo, FeRh or permalloy) both in the form of bilayers and multilayers. The most significant results will be highlighted.

  17. Soft tissue tumours: imaging strategy

    Energy Technology Data Exchange (ETDEWEB)

    Brisse, Herve J. [Institute Curie, Department of Radiology, Paris (France); Orbach, Daniel [Institute Curie, Department of Paediatric Oncology, Paris (France); Klijanienko, Jerzy [Institute Curie, Department of Pathology, Paris (France)

    2010-06-15

    Vascular tumours and malformations, fibrous and fibrohistiocytic tumours and pseudotumours are the most common benign soft-tissue masses observed in children, and can be treated conservatively. Rhabdomyosarcomas are the most frequent malignant tumours, accounting for about half of soft tissue sarcomas. A child referred for a soft-tissue mass should ideally be managed by a multidisciplinary team and primary excision should be proscribed until a definite diagnosis has been established. Clinical examination, conventional radiography and US with Doppler represent the first-line examinations and are sometimes sufficient to make a diagnosis. In all other situations, MRI is mandatory to establish the aggressiveness and extension of the tumour. This technique provides the relevant data to guide the decision regarding tissue sampling. (orig.)

  18. Soft Pneumatic Actuators for Rehabilitation

    Directory of Open Access Journals (Sweden)

    Guido Belforte

    2014-05-01

    Full Text Available Pneumatic artificial muscles are pneumatic devices with practical and various applications as common actuators. They, as human muscles, work in agonistic-antagonistic way, giving a traction force only when supplied by compressed air. The state of the art of soft pneumatic actuators is here analyzed: different models of pneumatic muscles are considered and evolution lines are presented. Then, the use of Pneumatic Muscles (PAM in rehabilitation apparatus is described and the general characteristics required in different applications are considered, analyzing the use of proper soft actuators with various technical properties. Therefore, research activity carried out in the Department of Mechanical and Aerospace Engineering in the field of soft and textile actuators is presented here. In particular, pneumatic textile muscles useful for active suits design are described. These components are made of a tubular structure, with an inner layer of latex coated with a deformable outer fabric sewn along the edge. In order to increase pneumatic muscles forces and contractions Braided Pneumatic Muscles are studied. In this paper, new prototypes are presented, based on a fabric construction and various kinds of geometry. Pressure-force-deformation tests results are carried out and analyzed. These actuators are useful for rehabilitation applications. In order to reproduce the whole upper limb movements, new kind of soft actuators are studied, based on the same principle of planar membranes deformation. As an example, the bellows muscle model and worm muscle model are developed and described. In both cases, wide deformations are expected. Another issue for soft actuators is the pressure therapy. Some textile sleeve prototypes developed for massage therapy on patients suffering of lymph edema are analyzed. Different types of fabric and assembly techniques have been tested. In general, these Pressure Soft Actuators are useful for upper/lower limbs treatments

  19. Soft Neutrosophic Bi-LA-semigroup and Soft Neutrosophic N-LA-seigroup

    Directory of Open Access Journals (Sweden)

    Mumtaz Ali

    2014-09-01

    Full Text Available Soft set theory is a general mathematical tool for dealing with uncertain, fuzzy, not clearly defined objects. In this paper we introduced soft neutrosophic biLA-semigroup,soft neutosophic sub bi-LA-semigroup, soft neutrosophic N -LA-semigroup with the discuission of some of their characteristics. We also introduced a new type of soft neutrophic bi-LAsemigroup, the so called soft strong neutrosophic bi-LAsemigoup which is of pure neutrosophic character. This is also extend to soft neutrosophic strong N-LA-semigroup. We also given some of their properties of this newly born soft structure related to the strong part of neutrosophic theory.

  20. Lessons learned from the first US/Russian Federation joint tabletop exercise to prepare for conducting on-site inspections under the Comprehensive Nuclear Test Ban Treaty

    Energy Technology Data Exchange (ETDEWEB)

    Filarowski, C; Kreek, S; Smith, A; Sweeney, J; Wild, J; Gough, R; Rockett, P; MacLeod, G; Hawkins, W; Wohletz, K; Knowles, S

    1999-03-24

    A U.S./Russian Federation Joint Tabletop Exercise took place in Snezhinsk, Russia, from 19 to 24 October 1998 whose objectives were to examine the functioning of an Inspection Team (IT) in a given scenario, to evaluate the strategies and techniques employed by the IT, to identify ambiguous interpretations of treaty provisions that needed clarification, and to confirm the overall utility of tabletop exercises to assist in developing an effective Comprehensive Test Ban Treaty (CTBT) verification regime. To achieve these objectives, the United States and Russian Federation (RF) agreed that two exercises would be conducted. The first would be developed by the RF, who would act as controller and as the inspected State Party (ISP), while the United States would play the role of the IT. The roles would be reversed in the second exercise; the United States would develop the scenario and play the ISP, while the RF would play the IT. A joint control team, comprised of members of both the U.S. and RF control teams, agreed on a number of ground rules for the two exercises and established a joint Evaluation Team to evaluate both of the exercises against the stated objectives. To meet time limitations, the scope of this joint exercise needed to be limited. The joint control team decided that each of the two exercises would not go beyond the first 25 days of an on-site inspection (OSI) and that the focus would be on examining the decision-making of the IT as it utilized the various technologies to clarify whether a nuclear test explosion had taken place. Hence, issues such as logistics, restricted access, and activities prior to Point of Entry (POE) would be played only to the extent needed to provide for a realistic context for the exercises' focus on inspection procedures, sensor deployments, and data interpretation. Each of the exercises began at the POE and proceeded with several iterations of negotiations between the IT and ISP, instrument deployments, and data