WorldWideScience

Sample records for circular bragg phenomenon

  1. Bragg transmission phase plates for the production of circularly polarized x-rays

    International Nuclear Information System (INIS)

    A thin-crystal Si (400) Bragg transmission x-ray phase plate has been constructed for the production of 5 to 12 keV circularly polarized x-rays. Using multiple beam diffraction from a GaAs crystal, a direct measurement of the degree of circular polarization as a function of off-Bragg position was made. These measurements indicated nearly complete circular polarization (|Pc| ≥ 0.95) and full helicity reversal on opposite sides of the rocking curve

  2. Imaging of an undulator source by phase circular Bragg-Fresnel lenses

    OpenAIRE

    Hartman, Ya.; Tarazona, E; Elleaume, P.; Snigireva, I.; Snigirev, A.

    1994-01-01

    Focusing properties and heatload resistance of a Bragg-Fresnel lens placed in an undulator beam have been demonstrated. The electron beam at an undulator source has been imaged by two setups using Bragg-Fresnel lenses. The first setup is a two-lenses telescope and the second one consists of one circular BFL and an asymmetrically cut crystal.

  3. Imaging of an undulator source by phase circular Bragg-Fresnel lenses

    International Nuclear Information System (INIS)

    Focusing properties and heatload resistance of a Bragg-Fresnel lens placed in an undulator beam have been demonstrated. The electron beam at an undulator source has been imaged by two setups using Bragg-Fresnel lenses. The first setup is a two-lenses telescope and the second one consists of one circular BFL and an asymmetrically cut crystal. (orig.)

  4. A double focusing SAXS camera with µm focal spot based on a circular bragg-fresnel lens

    OpenAIRE

    Snigirev, A.; Snigireva, I.; Riekel, C.; Miller, A.; Wess, L.; Wess, T.

    1993-01-01

    A 2D focusing SAXS camera has been build based on a circular Bragg-Fresnel lens. The camera has been tested at the Microfocus beamline at the European Synchrotron Radiation Facility. An undulator was used as radiation source. The focused beam size at the sample position of about 1,5*2µm2 and intensity of about 109 photons/s was obtained at a wavelength of 1.24A (10keV). A Molecular Dynamics image plate was used to detect the low-angle diffraction pattern. For native turkey leg tendon collagen...

  5. Acoustic excitation of the circular Bragg endash Fresnel lens in backscattering geometry

    International Nuclear Information System (INIS)

    An increment of the x-ray flux in crystal Bragg endash Fresnel lens (BFL) focus in backscattering geometry obtained by means of acoustic excitation of the BFL crystal substrate has been investigated. The dependence of the x ray close-quote s total reflected power versus ultrasound parameters has been studied in a low frequency range (10 endash 50 MHz). The proposed technique allows an increase in the flux in a BFL focus by a factor of 2 which almost achieves the kinematic limit. copyright 1997 American Institute of Physics

  6. Energy Harvester Based on the Synchronization Phenomenon of a Circular Cylinder

    Directory of Open Access Journals (Sweden)

    Junlei Wang

    2014-01-01

    Full Text Available A concept of generating power from a circular cylinder undergoing vortex-induced vibration (VIV was investigated. Two lead zirconate titanate (PZT beams which had high power density were installed on the cylinder. A theoretical model has been presented to describe the electromechanical coupling of the open-circuit voltage output and the vibration amplitudes based on a second-order nonlinear Van der pol equation and Gauss law. A numerical computation was applied to measure the capacity of the power generating system. The lift and drag coefficient and the vortex shedding frequency were obtained to verify how the nondimensional parameter reduced velocity Ur affects the fluid field. Meanwhile, a single-degree of freedom system has been added to describe the VIV, presynchronization, and synchronization together with postsynchronization regimes of oscillating frequencies. And the amplitudes of the vibration have been obtained. Finally, the vibrational amplitudes and the voltage output could go up to a high level in the synchronization region. The maximum value of the voltage output and the corresponding reduced velocity Ur were 8.42 V and 5.6, respectively.

  7. Bragg-Berry mirrors: reflective broadband q-plates

    CERN Document Server

    Rafayelyan, Mushegh

    2016-01-01

    We report on the experimental realization of flat mirrors enabling the broadband generation of optical vortices upon reflection. The effect is based on the geometric Berry phase associated with the circular Bragg reflection phenomenon from chiral uniaxial media. We show the reflective optical vortex generation from both diffractive and nondiffractive paraxial light beams using spatially patterned chiral liquid crystal films. The intrinsic spectrally broadband character of spin-orbit generation of optical phase singularities is demonstrated over the full visible domain. Our results do not rely on any birefringent retardation requirement and consequently foster the development of a novel generation of robust optical elements for spin-orbit photonic technologies.

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

    OpenAIRE

    Sun, Xiankai; Yariv, Amnon

    2009-01-01

    This is a continuation of our previous work [Opt. Express 16, 9155 (2008)]. In this paper we investigate the effect of nonuniform pumping on the modal properties of surface-emitting chirped circular grating lasers. By numerically solving the coupled-mode equations and matching the boundaries we compare and discuss the threshold pump levels and frequency detuning factors for three pumping profiles: uniform, Gaussian, and annular. Depending on the overlap of the pumping and modal profiles, Gaus...

  9. Mode characteristics of hollow core Bragg fiber

    Institute of Scientific and Technical Information of China (English)

    Minning Ji; Zhidong Shi; Qiang Guo

    2005-01-01

    Analytical expression to calculate propagation constant and mode field of the hollow core Bragg fiber is derived. Numerical results are presented. It is shown that the fundamental mode of the hollow core Bragg fiber is circularly symmetric TE01 mode with no polarization degeneracy, while the higher order mode may be HE11, TM01, or TE02 etc.. This property is different from conventional optical fiber that its fundamental mode is the linearly polarized HE11 mode and is polarization degeneracy.

  10. Are Bragg Peaks Gaussian?

    OpenAIRE

    Hammouda, Boualem

    2014-01-01

    It is common practice to assume that Bragg scattering peaks have Gaussian shape. The Gaussian shape function is used to perform most instrumental smearing corrections. Using Monte Carlo ray tracing simulation, the resolution of a realistic small-angle neutron scattering (SANS) instrument is generated reliably. Including a single-crystal sample with large d-spacing, Bragg peaks are produced. Bragg peaks contain contributions from the resolution function and from spread in the sample structure....

  11. Administrative Circulars

    CERN Multimedia

    Département des Ressources humaines

    2004-01-01

    Administrative Circular N° 2 (Rev. 2) - May 2004 Guidelines and procedures concerning recruitment and probation period of staff members This circular has been revised. It cancels and replaces Administrative Circular N° 2 (Rev. 1) - March 2000. Administrative Circular N° 9 (Rev. 3) - May 2004 Staff members contracts This circular has been revised. It cancels and replaces Administrative Circular N° 9 (Rev. 2) - March 2000. Administrative Circular N° 26 (Rev. 4) - May 2004 Procedure governing the career evolution of staff members This circular has also been revised. It Administrative Circulars Administrative Circular N° 26 (Rev. 3) - December 2001 and brings up to date the French version (Rev. 4) published on the HR Department Web site in January 2004. Operational Circular N° 7 - May 2004 Work from home This circular has been drawn up. Operational Circular N° 8 - May 2004 Dealing with alcohol-related problems...

  12. Bragg grating rogue wave

    CERN Document Server

    Degasperis, Antonio; Aceves, Alejandro B

    2015-01-01

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing, may lead to extreme waves at extremely low powers.

  13. Bragg grating rogue wave

    Energy Technology Data Exchange (ETDEWEB)

    Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

    2015-06-12

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

  14. Bragg Curve Spectroscopy

    International Nuclear Information System (INIS)

    An alternative utilization is presented for the gaseous ionization chamber in the detection of energetic heavy ions, which is called Bragg Curve Spectroscopy (BCS). Conceptually, BCS involves using the maximum data available from the Bragg curve of the stopping heavy ion (HI) for purposes of identifying the particle and measuring its energy. A detector has been designed that measures the Bragg curve with high precision. From the Bragg curve the range from the length of the track, the total energy from the integral of the specific ionization over the track, the dE/dx from the specific ionization at the beginning of the track, and the Bragg peak from the maximum of the specific ionization of the HI are determined. This last signal measures the atomic number, Z, of the HI unambiguously

  15. Raynaud's phenomenon

    DEFF Research Database (Denmark)

    Nielsen, S L; Christensen, N J; Olsen, N;

    1980-01-01

    forearm venous concentration of noradrenaline was lower and adrenaline concentration higher in the sympathectomized patients than in the other groups (p less than 0,05). Noradrenaline showed a significant increase during body cooling in normals and primary Raynaud's (p less than 0,05). There was no...... significant correlation between the vasoconstrictor response to cooling of a finger and the noradrenaline concentration probably due to the fact that skin vasoconstriction impeded release of noradrenaline from the skin. The relapse of Raynaud's phenomenon after surgically sufficient sympathectomy could not be...

  16. Effects of a ground plate on magnus effect of a rotating circular cylinder. 5th Report. Hysteretic phenomenon of fluid force and numerical analysis by the finite difference method; Jimen ni kinsetsushite kaitensuru ento mawari no nagare. 5. Ryutairyoku no hisuterishisuna gensho to sabunhoni yoru suchi kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Kano, I. [Yamagata University, Yamagata (Japan). Faculty of Engineering

    2000-01-25

    The flow around a rotating circular cylinder that is close to a moving plate has been investigated numerically and experimentally for the high Reynolds number (Re=3.3 x 10{sup 4}-5 x 10{sup 4}). Two different flow patterns were observed under the same conditions by changing peripheral velocity of the circular cylinder. The transition of the flow pattern occurs when the jet through a small gap (H/D =0.1) switches from the moving plate to the cylinder wall. This phenomenon is known as some kind of the Coanda effect. Furthermore the Coanda effect was accompanied by hysteretic effect. Computation of the two-dimensional unsteady Navier-Stokes equations was also conducted. The numerical results qualitatively agreed with the experimental ones. It was found that the Coanda effect and the hysteretic phenomenon were greatly related to the standing vortex that exists behind the cylinder. (author)

  17. Raynaud's phenomenon.

    Science.gov (United States)

    Hughes, Michael; Herrick, Ariane L

    2016-02-01

    Raynaud's phenomenon (RP) is a major cause of pain and disability in patients with autoimmune connective tissue diseases (CTDs), particularly systemic sclerosis (SSc). The clinician must perform a comprehensive clinical assessment in patients with RP to differentiate between primary (idiopathic) and secondary RP, in particular (for rheumatologists), secondary to an autoimmune CTD, as both the prognosis and treatment may differ significantly. Key investigations are nailfold capillaroscopy and testing for autoantibodies (in particular, those associated with SSc). Patients with RP and either abnormal nailfold capillaroscopy or an SSc-specific antibody (and especially with both) have a high risk of transitioning to an autoimmune CTD. Both nailfold capillaroscopy and autoantibody specificity may help the clinician in predicting organ-based complications. The management of CTD-associated RP requires a multifaceted approach to treatment, including patient education and conservative ('non-drug') measures. Patients with CTD-associated RP often require pharmacological treatment, which in the first instance is usually a calcium channel blocker, although other agents can be used. There is an increasing tendency to use phosphodiesterase type 5 inhibitors early in the treatment of CTD-associated RP. Oral therapies are commonly associated with side effects (often due to systemic vasodilation) that may result in failure of dose escalation and/or permanent discontinuation. Intravenous prostanoid therapy and surgery (e.g., botulinum toxin injection and digital sympathectomy) can be considered in severe RP. Patients with CTD-associated RP can develop a number of ischaemic digital complications (primarily ulcers and critical ischaemia), which may be associated with significant tissue loss. Future research is required to increase the understanding of the pathogenesis and natural history of RP (to drive therapeutic advances), and to explore/develop drug therapies, including those that

  18. Supersymmetric Bragg gratings

    International Nuclear Information System (INIS)

    The supersymmetric (SUSY) structure of coupled-mode equations that describe scattering of optical waves in one-dimensional Bragg gratings is highlighted. This property can find applications to the synthesis of special Bragg filters and distributed-feedback (DFB) optical cavities. In particular, multiple SUSY (Darboux–Crum) transformations can be used to synthesize DFB filters with any desired number of resonances at target frequencies. As an example, we describe the design of a DFB structure with a set of equally-spaced resonances, i.e. a frequency comb transmission filter. (paper)

  19. Double Bragg Interferometry.

    Science.gov (United States)

    Ahlers, H; Müntinga, H; Wenzlawski, A; Krutzik, M; Tackmann, G; Abend, S; Gaaloul, N; Giese, E; Roura, A; Kuhl, R; Lämmerzahl, C; Peters, A; Windpassinger, P; Sengstock, K; Schleich, W P; Ertmer, W; Rasel, E M

    2016-04-29

    We employ light-induced double Bragg diffraction of delta-kick collimated Bose-Einstein condensates to create three symmetric Mach-Zehnder interferometers. They rely on (i) first-order, (ii) two successive first-order, and (iii) second-order processes which demonstrate the scalability of the corresponding momentum transfer. With respect to devices based on conventional Bragg scattering, these symmetric interferometers double the scale factor and feature a better suppression of noise and systematic uncertainties intrinsic to the diffraction process. Moreover, we utilize these interferometers as tiltmeters for monitoring their inclination with respect to gravity. PMID:27176520

  20. Silicon graphene Bragg gratings

    OpenAIRE

    Capmany, Jose; Domenech, David; Munoz, Pascual

    2013-01-01

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

  1. Information Circulars

    International Nuclear Information System (INIS)

    Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars which were of current interest on 15 January 1969 is given below, followed by an index to their subject matter. Other circulars can be traced by reference to earlier issues of the present document.

  2. Efectos rotacionales en redes de Bragg en fibras ópticas

    OpenAIRE

    Arce Diego, José Luis; Muriel Fernández, Miguel Ángel; López Ruisánchez, Roberto; López Higuera, José Miguel

    1997-01-01

    The periodic mode coupling between the right and left circular polarization modes that is induced by a photoinduced fiber grating, with or without lineal birefringence, and with a magnetic field or a twist rate applied to it, is studied and analyzed through the use of the generalized coupled-mode theory. Several novel application of such devices as a fiber Bragg grating twist rate probe, a tuneable optical fiber based on twisted fiber Bragg grating, and an optical filter tuned by magnetic fie...

  3. Bragg reflection program

    International Nuclear Information System (INIS)

    This user's guide to the Bragg Reflection Program (BRP) is in the nature of an informal report. The general purpose of BRP is to scan a series of Bragg reflections automatically in order to obtain profiles and integrated intensities. The program is used in conjunction with the SUPERVISOR and READ packages, and the procedures for using it are similar to those for the Triple-Axis Control program. All the general features of the system, SUPERVISOR and READ packages as described in the Spectrometer Control Systems User's Guide are preserved. The presentation assumes that the reader is familiar with these. Sections are given on the READ package, execution and use, error messages, and output. A few sample problems are shown. (1 figure) (U.S.)

  4. Information circulars

    International Nuclear Information System (INIS)

    Information circulars are published from time to time under the symbol INFCIRC/... for the purpose of bringing matters of general interest to the attention of all Members of the Agency. The present revision contains INFCIRCs published up to mid-August 1994. A complete numerical list of information circulars is reproduced with their titles in the Annex

  5. Information circulars

    International Nuclear Information System (INIS)

    The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Members of the Agency. This revision contains INFCIRCs published up to mid-August 1992. A complete numerical lift of Information Circulars with their titles is reproduced in an Annex

  6. Information circulars

    International Nuclear Information System (INIS)

    The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Member States. This revision contains INFCIRCs published up to the end of May 1999, grouped by field of activity. A complete list of information circulars in numerical order is given in an annex

  7. Information Circulars

    International Nuclear Information System (INIS)

    Information circulars are published from time to time under the symbol INFCIRC/. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current on 31 December 1964 is given, followed by an index to their subject matter.

  8. Information circulars

    International Nuclear Information System (INIS)

    The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Member States. This revision contains INFCIRCs published up to February 1997, grouped by field of activity. A complete list of information circulars in numerical order is given in an annex

  9. Information circulars

    International Nuclear Information System (INIS)

    Information circulars are published from time to time under the symbol INFCIRC/... for the purpose of bringing matters of general interest to the attention of all Members of the Agency. The present revision contains INFCIRCs published up to the end of April 2002. A complete numerical list of information circulars is reproduced with their titles in the Annex

  10. What Is Raynaud's Phenomenon?

    Science.gov (United States)

    ... Phenomenon PDF Version Size: 59 KB November 2014 What Is Raynaud’s Phenomenon? Fast Facts: An Easy-to- ... use tools that vibrate, such as a jackhammer. What Are the Symptoms of Raynaud’s Phenomenon? The body ...

  11. Circular Updates

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Circular Updates are periodic sequentially numbered instructions to debriefing staff and observers informing them of changes or additions to scientific and specimen...

  12. Information circulars

    International Nuclear Information System (INIS)

    The document summarizes the information circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Members of the Agency. In the main body of the document only those documents which are regarded as likely to be of current interest are listed. A complete numerical list of information circulars with their titles is reproduced in the Annex

  13. Fabrication and optical characterization of Bragg resonance luminescence porous silicon

    Science.gov (United States)

    Park, Mi-Ae; Sohn, Honglae

    2016-01-01

    The synthesis and characterization of Bragg resonance luminescence porous silicon (BRL PS) exhibiting both optical reflectivity and strong narrow visible photoluminescence (PL) prepared from highly doped n-type silicon wafers through the electrochemical etching are reported. BRL PS showing the luminescence at 702 nm with an excitation wavelength of 400 nm was prepared by applying the current of 360 mA cm-2 for 1.6 s and 75 mA cm-2 for 3.6 s with 50 repeats in etching solution of 1:1 volume mixture of absolute ethanol and aqueous 48% HF. BRL PS exhibited sharp PL peak which reached full width at half maximum of 14 nm, originated from the result of Bragg resonance in PS multilayer. The sharp PL peak at 702 nm of BRL PS is the second-order transmitted luminescence peak by Bragg resonance phenomenon. The simultaneous measurement of reflectivity and luminescence in the BRL PS under an exposure to a vapor flux of acetone showed that a narrow transmitted luminescence based on Bragg resonance in BRL PS quenched as well as the red-shifted by 37 nm of reflection wavelength was observed. A dramatic quenching PL of BRL PS compare to that of the monolayer PS, is probably due to the Bragg resonance effect on luminescence.

  14. Operational Circulars

    CERN Document Server

    2003-01-01

    Operational Circular N° 4 - April 2003 Conditions for use by members of the CERN personnel of vehicles belonging to or rented by CERN - This circular has been drawn up. Operational Circular N° 5 - October 2000 Use of CERN computing facilities - Further details on the personal use of CERN computing facilities Operational Circular N° 5 and its Subsidiary Rules http://cern.ch/ComputingRules defines the rules for the use of CERN computing facilities. One of the basic principles governing such use is that it must come within the professional duties of the user concerned, as defined by the user's divisional hierarchy. However, personal use of the computing facilities is tolerated or allowed provided : a) It is in compliance with Operational Circular N° 5 and not detrimental to official duties, including those of other users; b) the frequency and duration is limited and there is a negligible use of CERN resources; c) it does not constitute a political, commercial and/or profit-making activity; d) it is not...

  15. Circular polarization observed in bioluminescence

    NARCIS (Netherlands)

    Wijnberg, Hans; Meijer, E.W.; Hummelen, J.C.; Dekkers, H.P.J.M.; Schippers, P.H.; Carlson, A.D.

    1980-01-01

    While investigating circular polarization in luminescence, and having found it in chemiluminescence, we have studied bioluminescence because it is such a widespread and dramatic natural phenomenon. We report here that left and right lanterns of live larvae of the fireflies, Photuris lucicrescens and

  16. Information circulars

    International Nuclear Information System (INIS)

    The document summarizes the Information Circulars published by the IAEA under the symbol INFCIRC/ for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A complete list of INFCIRCs in numerical order with their titles is given in the Annex

  17. A highly sensitive fiber Bragg grating diaphragm pressure transducer

    Science.gov (United States)

    Allwood, Gary; Wild, Graham; Lubansky, Alex; Hinckley, Steven

    2015-10-01

    In this work, a novel diaphragm based pressure transducer with high sensitivity is described, including the physical design structure, in-depth analysis of optical response to changes in pressure, and a discussion of practical implementation and limitations. A flat circular rubber membrane bonded to a cylinder forms the body of the transducer. A fiber Bragg grating bonded to the center of the diaphragm structure enables the fractional change in pressure to be determined by analyzing the change in Bragg wavelength of the reflected spectra. Extensive evaluation of the physical properties and optical characteristics of the transducer has been performed through experimentation, and modeling using small deformation theory. The results show the transducer has a sensitivity of 0.116 nm/kPa, across a range of 15 kPa. Ultra-low cost interrogation of the optical signal was achieved through the use of an optically mismatched Bragg grating acting as an edge filter to convert the spectral change into an intensity change. A numerical model of the intensity based interrogation was implemented in order to validate the experimental results. Utilizing this interrogation technique and housing both the sensing and reference Bragg gratings within the main body of the transducer means it is effectively temperature insensitive and easily connected to electronic systems.

  18. Acoustical “transparency” induced by local resonance in Bragg bandgaps

    International Nuclear Information System (INIS)

    We show that sound waves can resonantly transmit through Bragg bandgaps in an acoustical duct periodically attached with an array of Helmholtz resonators, forming within the normally forbidden band a transparency window with group velocity smaller than the normal speed of sound. The transparency occurs for the locally resonant frequency so much close to the Bragg one that both the local-resonance-induced bandgap and the Bragg one heavily overlap with each other. The phenomenon seems an acoustical analog of the well-known electromagnetically induced transparency by quantum interference. Different from the Fano-like interference explanation, we also provide a mechanism for the transparency window phenomenon which makes it possible to extend the phenomenon in general

  19. Acoustical “transparency” induced by local resonance in Bragg bandgaps

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Gaokun; Wang, Xinlong, E-mail: xlwang@nju.edu.cn [Key Laboratory of Modern Acoustics and Institute of Acoustics, Nanjing University, Nanjing 210093 (China)

    2014-01-28

    We show that sound waves can resonantly transmit through Bragg bandgaps in an acoustical duct periodically attached with an array of Helmholtz resonators, forming within the normally forbidden band a transparency window with group velocity smaller than the normal speed of sound. The transparency occurs for the locally resonant frequency so much close to the Bragg one that both the local-resonance-induced bandgap and the Bragg one heavily overlap with each other. The phenomenon seems an acoustical analog of the well-known electromagnetically induced transparency by quantum interference. Different from the Fano-like interference explanation, we also provide a mechanism for the transparency window phenomenon which makes it possible to extend the phenomenon in general.

  20. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

  1. ADMINISTRATIVE CIRCULARS

    CERN Multimedia

    Division des ressources humaines

    2000-01-01

    N° 2 (Rev. 1) - March 2000Guidelines and procedures concerning recruitment and probation period of staff membersN° 9 (Rev. 2) - March 2000Staff members contractsN° 16 (Rev. 2) - January 2000TrainingN° 30 (Rev. 1) - January 2000Indemnities and reimbursements upon taking up appointment and termination of contractN° 32 - February 2000Principles and procedures governing complaints of harassmentThese circular have been amended (No 2, N° 9, N° 16 and N° 30) or drawn up (N° 32).Copies are available in the Divisional Secretariats.Note:\tAdministrative and operational circulars, as well as the lists of those in force, are available for consultation in the server SRV4_Home in the Appletalk zone NOVELL (as GUEST or using your Novell username and password), volume PE Division Data Disk.The Word files are available in the folder COM, folder Public, folder ADM.CIRC.docHuman Resources DivisionTel. 74128

  2. Detecting deformations in uncompacted strata by fiber Bragg grating sensors incorporated into GFRP

    Energy Technology Data Exchange (ETDEWEB)

    Chai, J.; Liu, J.X.; Qiu, B.A.; Li, Y.; Zhu, L.; Wei, S.M.; Wang, Z.P.; Zhang, G.W.; Yang, J.H. [Xian University of Science & Technology, Xian (China). School of Energy Engineering

    2011-01-15

    Coalfields based in east China, such as Huaibei, Datun, Xuzhou, Yanzhou, Yongxia and Huainan, have suffered paroxysmal shaft lining fracture and repeated deformation after repair in the last three decades. This phenomenon has required the development of fractured shaft lining repairing technology and a method for detecting rock strata settlement. It is proposed in this paper that, with the method of fiber Bragg grating sensor incorporated into GFRP, a sensing network of fiber Bragg grating wavelength division multiplexing (WDM)/spatial division multiplexing (SDM) mixing array composed of 18 fiber gratings is formed, and it is used for monitoring the settlement of uncompacted hydrous strata. It is the first time that the fiber Bragg grating sensing system is embedded into the 180-m deep uncompacted strata, and the field experiments are conducted at No. 3 Jingning Coal Mine. The layout of optical sensors, the fiber Bragg grating detecting system, the drilling of the borehole and the embedding method of fiber Bragg grating sensors are introduced. The monitoring results of fiber Bragg grating sensors are compared with groundwater level monitoring results. Engineering practice shows that the fiber Bragg grating sensors are working normally and they can be used to detect strain safely and stably.

  3. Weldable fibre Bragg grating sensors for steel bridge monitoring

    International Nuclear Information System (INIS)

    For applications related to the structural health monitoring of steel bridges, novel weldable strain and temperature sensors based on fibre Bragg gratings were developed. These sensors, which can be directly welded to metallic structures, reveal linear responses over typical required measurement ranges and stability over thousands of load and temperature cycles. Proper installation procedures and in-field mechanical protection were also developed and implemented. The significance of the developed sensors was demonstrated through the installation of a complete sensing network on a new circular pedestrian bridge in Aveiro, Portugal, where it was used for loading tests, and also for in-service monitoring of its structural health

  4. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren;

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  5. The Lazarus phenomenon.

    Science.gov (United States)

    Sahni, Vaibhav

    2016-08-01

    The Lazarus phenomenon or the unassisted return of spontaneous circulation after cardiac arrest is a grossly underreported phenomenon in medical literature which essentially implies the 'resurrection' of an individual after cardiac arrest. Although there have been a handful of such cases reported, the clinical incidence and significance may be underestimated. Because of the presumed infrequency of this condition, there are no studies specifically researching Lazarus phenomenon in scientific literature. This review intends to systematically present current and past knowledge on this rare but definitive phenomenon. Research databases namely Google Scholar, Science Direct, Medline and PubMed were utilized. Only articles which identified cases where the return of spontaneous circulation occurred after cessation of Cardiopulmonary Resuscitation (CPR), and review articles on the entity were included. The mentioned databases were searched using the terms 'Lazarus phenomenon', 'cardiopulmonary resuscitation' and 'return of spontaneous circulation'. A literature review was synthesised based on articles meeting the eligibility criteria to better understand the phenomenon of return of spontaneous circulation. PMID:27540490

  6. The Lazarus phenomenon

    Science.gov (United States)

    2016-01-01

    The Lazarus phenomenon or the unassisted return of spontaneous circulation after cardiac arrest is a grossly underreported phenomenon in medical literature which essentially implies the ‘resurrection’ of an individual after cardiac arrest. Although there have been a handful of such cases reported, the clinical incidence and significance may be underestimated. Because of the presumed infrequency of this condition, there are no studies specifically researching Lazarus phenomenon in scientific literature. This review intends to systematically present current and past knowledge on this rare but definitive phenomenon. Research databases namely Google Scholar, Science Direct, Medline and PubMed were utilized. Only articles which identified cases where the return of spontaneous circulation occurred after cessation of Cardiopulmonary Resuscitation (CPR), and review articles on the entity were included. The mentioned databases were searched using the terms ‘Lazarus phenomenon’, ‘cardiopulmonary resuscitation’ and ‘return of spontaneous circulation’. A literature review was synthesised based on articles meeting the eligibility criteria to better understand the phenomenon of return of spontaneous circulation.

  7. Circularly polarized lasing in chiral modulated semiconductor microcavity with GaAs quantum wells

    CERN Document Server

    Demenev, A A; Schneider, C; Brodbeck, S; Kamp, M; Höfling, S; Lobanov, S V; Weiss, T; Gippius, N A; Tikhodeev, S G

    2016-01-01

    We report the elliptically, close to circularly polarized lasing at $\\hbar\\omega = 1.473$ and 1.522 eV from an AlAs/AlGaAs Bragg microcavity with 12 GaAs quantum wells in the active region and chiral-etched upper distributed Bragg refractor under optical pump at room temperature. The advantage of using the chiral photonic crystal with a large contrast of dielectric permittivities is its giant optical activity, allowing to fabricate a very thin half-wave plate, with a thickness of the order of the emitted light wavelength, and to realize the monolithic control of circular polarization.

  8. Mask Phenomenon in Communication

    Institute of Scientific and Technical Information of China (English)

    郎丽璇

    2013-01-01

    People sometimes wear masks. Abusive expression may be used to convey love while polite words can be exchanged among enemies. This essay describes and discusses this special phenomenon in communication and analyzes the elements that con-tribute to the success of a mask communication.

  9. What Is Raynaud's Phenomenon?

    Science.gov (United States)

    ... is most common in:  Women.  People living in cold places. The secondary form tends to start after age 35 to 40. ... may be more likely to get the secondary form:  Workers who are around ... Phenomenon? The body saves heat when it is cold by slowing the supply of blood to the ...

  10. Fiber Bragg Grating Based Thermometry

    OpenAIRE

    Ahmed, Zeeshan; Filla, James; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined m...

  11. BESSY Bragg-Fresnel multilayer beam monitors

    International Nuclear Information System (INIS)

    X-ray optical systems based on Bragg-Fresnel multilayer components imaging an electron beam in a storage ring with microm resolution are presented. Design concepts are compared to alternative methods, and the aberrations and limits of Bragg-Fresnel multilayer optics are discussed. Experimental results of imaging the BESSY 1 source with sub 10 microm resolution are presented and the development of a compact Bragg-Fresnel multilayer telescope as a BESSY 2 standard beam monitor is described

  12. Berry phase of light Bragg-reflected by chiral liquid crystal media

    CERN Document Server

    Barboza, Raouf; Residori, Stefania; Clerc, Marcel G

    2016-01-01

    Berry phase is revealed for circularly polarized light when it is Bragg-reflected by a chiral liquid crystal medium of the same handedness. By using a chiral nematic layer we demonstrate that if the input plane of the layer is rotated with respect to a fixed reference frame, then, a geometric phase effect occurs for the circularly polarized light reflected by the periodic helical structure of the medium. Theory and numerical simulations are supported by an experimental observation, disclosing novel applications in the field of optical manipulation and fundamental optical phenomena.

  13. Synchronization: The ratchet phenomenon

    International Nuclear Information System (INIS)

    In this paper some simple models of coupled oscillators are defined. They are used as tools to analyze properties of synchronization domains. It is possible to get the general organization of these domains (generally known as tongues), particularly when the coupling or the forcing signal is 'square'. At large forcing a phenomenon, very similar to the ratchet wheel mechanism, takes place and many synchronization domains disappear. Generally the tongue associated with the relative winding number 1/1 becomes predominant and only tongues with relative winding number p/q < 1 remain. This phenomenon is rather general and appears in many real situations. It is related with motion and transport in physical and biological sciences.

  14. The Laurent phenomenon

    OpenAIRE

    Fomin, Sergey; Zelevinsky, Andrei

    2001-01-01

    A composition of birational maps given by Laurent polynomials need not be given by Laurent polynomials; however, sometimes---quite unexpectedly---it does. We suggest a unified treatment of this phenomenon, which covers a large class of applications. In particular, we settle in the affirmative a conjecture of D.Gale and R.Robinson on integrality of generalized Somos sequences, and prove the Laurent property for several multidimensional recurrences, confirming conjectures by J.Propp, N.Elkies, ...

  15. [Lazarus phenomenon: spontaneous resuscitation].

    Science.gov (United States)

    Casielles García, J L; González Latorre, M V; Fernández Amigo, N; Guerra Vélz, A; Cotta Galán, M; Bravo Capaz, E; de las Mulas Béjar, M

    2004-01-01

    A 94-year-old woman undergoing surgery for simple repair of a duodenal perforation experienced a sudden massive hemorrhage (1500 mL) when the duodenum was separated from adjacent structures. Hemodynamic stability was re-established when fluids were replaced. After the abdominal wall was closed, increased amplitude of the QRS wave was observed and heart rate slowed until there was no pulse. Electromechanical dissociation (EMD) was diagnosed and cardiopulmonary resuscitation was started. When EMD persisted after 40 minutes, resuscitative measures were stopped and the ventilator was disconnected, though orotracheal intubation and arterial and electrocardiographic monitoring were maintained. After 2 or 3 minutes, heart rhythm restarted spontaneously and arterial pressure waves reappeared on the monitor. The patient progressed well for 72 hours, after which she developed septic shock and multiorgan failure, dying 18 days later. The Lazarus phenomenon may be more common than the medical literature would indicate, possibly because a large gap in our understanding of the pathophysiology of the phenomenon underlies anecdotes about "miracles". As we wait for adequate international consensus on a protocol for monitoring the withdrawal of resuscitative measures, we should act prudently before definitively certifying death. The case we report occurred during a surgical intervention in which the patient had received general anesthesia. We believe that the causes that might explain the Lazarus phenomenon are quite different in that context than they would be in a nonsurgical setting, such that it would be useful to create a national database to keep a record of such intraoperative events. PMID:15495638

  16. The Void Phenomenon Revisited

    CERN Document Server

    Giovanelli, Riccardo

    2009-01-01

    The Void Phenomenon consists in the apparent discrepancy between the number of observed dwarf halos in cosmic voids and that expected from CDM simulations. We approach the problem considering the challenging prospects of detecting field dwarf systems with halo masses < 10^9 solar, via their possible HI emission. A brief review of recent work is followed by preliminary results from the ALFALFA survey, which suggest the possibility, but not yet the proof, that such objects may have been already detected towards the outskirts of the Local Group.

  17. Kasabach-Merritt phenomenon

    International Nuclear Information System (INIS)

    An association between a vascular lesion and a life threatening coagulopathy is called Kasabach-Merritt phenomenon (KMP). It includes thrombocytopenia, microangiopathic hemolytic anemia, and disseminated intravascular coagulopathy. We can not overstate the need for excellent and careful screening. Treatment modalities of KMP have included medication, radiation, embolization and surgery. Corticosteroids have traditionally been the mainstay of treatment. We report a 4-months-old girl with an extensive vascular lesion involving the left parotid, submandibular, and parapharyngeal regions, and with KMP. We treated her with a mega dose of corticosteroids. Her coagulopathy resolved, and her vascular lesion improved. (author)

  18. Circularity and Lambda Abstraction

    DEFF Research Database (Denmark)

    Danvy, Olivier; Thiemann, Peter; Zerny, Ian

    2013-01-01

    In this tribute to Doaitse Swierstra, we present the rst transformation between lazy circular programs a la Bird and strict cir- cular programs a la Pettorossi. Circular programs a la Bird rely on lazy recursive binding: they involve circular unknowns and make sense equa- tionally. Circular...... unknowns from what is done to them, which we lambda-abstract with functions. The circular unknowns then become dead variables, which we eliminate. The result is a strict circu- lar program a la Pettorossi. This transformation is reversible: given a strict circular program a la Pettorossi, we introduce...

  19. Fiber Bragg Grating Based Thermometry

    CERN Document Server

    Ahmed, Zeeshan; Guthrie, William; Quintavalle, John

    2016-01-01

    In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of ~500 mK. Our measurements indicate that the combined measurement uncertainty is dominated by uncertainty in determining the peak center fitting and by thermal aging of polyimide coated fibers.

  20. High order Bragg grating microfluidic dye laser

    DEFF Research Database (Denmark)

    Balslev, Søren; Kristensen, Anders

    2004-01-01

    We demonstrate a single mode distributed feedback liquid dye laser, based on a short 133 'rd order Bragg grating defined in a single polymer layer between two glass substrates.......We demonstrate a single mode distributed feedback liquid dye laser, based on a short 133 'rd order Bragg grating defined in a single polymer layer between two glass substrates....

  1. Focusing properties of ellipsoidal Bragg-Fresnel multilayer lenses

    International Nuclear Information System (INIS)

    Principles of calculation of the Bragg-Fresnel multilayer lenses (BFL) structure topology and the first results of test of ellipsoidal BFL using the Sibir'-1 synchrotron radiation source are presented. The picture of cross section of the rotation ellipsoids of the equal phase surfaces by the multilayer structure under the angle to the optical axis was used as the initial model of calculation of the BFL structure. As a result of this experiment, the pictures, reduced by a factor of 350, in the region of X-ray generation with 4.5 nm wavelength are obtained; focusing properties of ellipsoidal BFL with a circular form of a focal pit are demonstrated for the first time

  2. Circular-rubbing Manipulation

    Institute of Scientific and Technical Information of China (English)

    SHEN Guo-quan; XIAO Yuan-chun

    2003-01-01

    @@ "Mo" literally means "rubbing between two things"and "eliminating". Circular-rubbing is one of the earliest manipulations used in clinical practice. Circular-rubbing differs from pressing actually. Pressing is a static manipulation and acts to inhibit motion; circular-rubbing is a movable manipulation and serves to eliminate stationary. Circular-rubbing can be performed by either the palm or the finger.

  3. The Oklo phenomenon

    International Nuclear Information System (INIS)

    During 1972, research workers of the French Commissariat a I'Energie Atomique made an astonishing discovery: fission chain reactions had been triggered spontaneously in the very remote past within a uranium deposit in Gabon and parts of the deposit had behaved like a modern nuclear reactor for hundreds of thousands of years. Subsequent investigations showed that the reaction sites had remained in a remarkable state of preservation, so that detailed study was possible. he IAEA felt that the Oklo phenomenon would be an excellent subject for international co-operation in fundamental research and agreed to the suggestion of the Gabon Government and the French Commissariat a I'Energie Atomique that a jointly organized symposium be held. The symposium will take place at Franceville, Gabon, from 23 to 27 June 1975. (author)

  4. The neutron channeling phenomenon.

    Science.gov (United States)

    Khanouchi, A; Sabir, A; Boulkheir, M; Ichaoui, R; Ghassoun, J; Jehouani, A

    1997-01-01

    Shields, used for protection against radiation, are often pierced with vacuum channels for passing cables and other instruments for measurements. The neutron transmission through these shields is an unavoidable phenomenon. In this work we study and discuss the effect of channels on neutron transmission through shields. We consider an infinite homogeneous slab, with a fixed thickness (20 lambda, with lambda the mean free path of the neutron in the slab), which contains a vacuum channel. This slab is irradiated with an infinite source of neutrons on the left side and on the other side (right side) many detectors with windows equal to 2 lambda are placed in order to evaluate the neutron transmission probabilities (Khanouchi, A., Aboubekr, A., Ghassoun, J. and Jehouani, A. (1994) Rencontre Nationale des Jeunes Chercheurs en Physique. Casa Blanca Maroc; Khanouchi, A., Sabir, A., Ghassoun, J. and Jehouani, A. (1995) Premier Congré International des Intéractions Rayonnements Matière. Eljadida Maroc). The neutron history within the slab is simulated by the Monte Carlo method (Booth, T. E. and Hendricks, J. S. (1994) Nuclear Technology 5) and using the exponential biasing technique in order to improve the Monte Carlo calculation (Levitt, L. B. (1968) Nuclear Science and Engineering 31, 500-504; Jehouani, A., Ghassoun, J. and Aboubker, A. (1994) In Proceedings of the 6th International Symposium on Radiation Physics, Rabat, Morocco). Then different geometries of the vacuum channel have been studied. For each geometry we have determined the detector response and calculated the neutron transmission probability for different detector positions. This neutron transmission probability presents a peak for the detectors placed in front of the vacuum channel. This study allowed us to clearly identify the neutron channeling phenomenon. One application of our study is to detect vacuum defects in materials. PMID:9463884

  5. Air core Bragg fibers for delivery of near-infrared laser radiation

    Science.gov (United States)

    Jelínek, Michal; Frank, Milan; Kubeček, Václav; Matějec, Vlastimil; Kašík, Ivan; Podrazký, Ondřej

    2014-12-01

    Optical fibers designed for high power laser radiation delivery represent important tools in medicine, solar systems, or industry. For such purposes several different types of glass optical fibers such as silica, sapphire, or chalcogenide ones as well as hollow-glass fibers, photonic crystal fibers and Bragg fibers have been investigated. Air-core Bragg fibers or photonic crystal fibers offer us the possibility of light transmission in a low dispersive material - air having a high damage threshold and small non-linear coefficient. However, preforms for drawing Bragg fibers can be fabricated by MCVD method similarly as preforms of standard silica fibers. In this paper we present fundamental characteristics of laboratory-designed and fabricated Bragg fibers with air cores intended for delivery of laser radiation at a wavelength range from 0.9 to 1.5 μm. Bragg fibers with different air core diameters of 5, 45 and 73 mm were prepared. The fiber core was surrounded by three pairs of circular Bragg layers. Each pair was composed of one layer with a high and one layer with a low refractive index with a contrast up to 0.03. Several laser sources emitting at 0.975, 1.06, and 1.55 μm were used as radiation sources. Attenuation coefficients, overall transmissions, bending losses, and spatial profiles of output beams from fibers were determined at these wavelengths. The lowest attenuation coefficient of 70 dB/km was determined for the 45 μm and 73 mm air-core fiber when radiation from a laser was launched into the fibers by using optical lenses. However, multimodal transmission has been observed in such condition. It has also been found that bending losses of such fibers are negligible for bending diameters higher than 15 mm.

  6. New aspects in the Bragg Glass-Disordered phase transition: an analysis based on the 3rd harmonics of the AC magnetic susceptibility

    OpenAIRE

    Adesso*, M. G.; Flukiger, R.; Giamarchi, T.; Goldacker, W.; H.; Kupfer; Pace, S.; Polichetti, M.; Uglietti, D.

    2007-01-01

    We analyse the phase transition between the Bragg Glass and the Disordered phase in the vortex lattice in type-II superconductors, both by analytical computations and experimental investigations. It is known that if the Peak Effect can be detected, a Bragg Glass/Disordered phase transition takes place. We show that, in some conditions, this transition can occur without the observation of the Peak Effect Phenomenon. We introduce a method based on the 3rd harmonics of the AC magnetic susceptibi...

  7. Reflectivity and Braggs Wavelength in FBG

    Directory of Open Access Journals (Sweden)

    Dinesh Arora

    2011-12-01

    Full Text Available We have presented an analytical model of splitters based on Fiber Bragg grating used to detect a Bragg wavelength from the number of wavelengths which are traveling in an optical fiber. The number of grids and grating length can be used as a wavelength shifter.This paper presents experimental results that are used to show the effect of number of grids and the length of the grating on the Bragg wavelength and reflectivity of Fiber Bragg Grating (FBG. The pitch of grating is directly proportional to the grating length and inversely proportional to number of grids. When the grating length is fixed and the number of grids is increased, the Bragg wavelength decreases and reflectivity increases. This increase in reflectivity is very small. Further when the number of grids was kept constant and the grating length was increased the Bragg wavelength increases. The effect of this increase in grating length on reflectivity is a very small. In our model, the effectiveness of the grating in extracting the Braggs wavelength is nearly 100%.

  8. The Offshoring Phenomenon

    Directory of Open Access Journals (Sweden)

    Mery Patricia Tamayo Plata

    2014-06-01

    Full Text Available This paper explains some definitions which are necessary in order to understand the offshoring concept, going through the most relevant works about the development of the offshoring phenomenon and its impact on the demand for labor and on the most skilled workers' income. It is evidenced that the offshoring processes not only deal with the purchase and sale of goods anymore, but that the service sector has an increasingly important role, and that the lower cost is not the only aspect that matters when offshoring, but aspects such as the language and culture are also considered. It is also found that technology and research related services flow not only from the parent companies towards its subsidiaries, but from firms in less developed countries to other companies in advanced countries. It concludes with a review of the works that explores the relationship between offshoring, employment and wages, from both, a macro and microeconomic outlook. In the latter case, special consideration is given to the work carried out by Amity and Wei (2006, Crinó (2010, and Geishecker and Görg (2013.

  9. BESSY Bragg-Fresnel multilayer beam monitors

    International Nuclear Information System (INIS)

    X-ray optical systems based on Bragg-Fresnel multilayer components imaging an electron beam in a storage ring with μm resolution are presented. Design concepts are compared to alternative methods, and the aberrations and limits of Bragg-Fresnel multilayer optics are discussed. Experimental results of imaging the BESSY I source with sub-10-μm resolution are presented, and the development of a compact Bragg-Fresnel multilayer telescope as a BESSY II standard beam monitor is described. copyright 1996 American Institute of Physics

  10. Preparation and Characterization of Bragg Fibers for Delivery of Laser Radiation at 1064 nm

    Directory of Open Access Journals (Sweden)

    V. Matejec

    2013-04-01

    Full Text Available Bragg fibers offer new performance for transmission of high laser energies over long distances. In this paper theoretical modeling, preparation and characterization of Bragg fibers for delivery laser radiation at 1064 nm are presented. Investigated Bragg fibers consist of the fiber core with a refractive index equal to that of silica which is surrounded by three pairs of circular layers. Each pair is composed of one layer with a high and one layer with a low refractive index and characterized by a refractive-index difference around 0.03. Propagation constants and radiation losses of the fundamental mode in such a structure were calculated on the basis of waveguide optics. Preforms of the Bragg fibers were prepared by the MCVD method using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. The fibers with a diameter of 170 m were drawn from the preforms. Refractive-index profiles, angular distributions of the output power and optical losses of the prepared fibers were measured. Results of testing the fibers for delivery radiation of a pulse Nd:YAG laser at 1064 nm are also shown.

  11. Strain imaging by Bragg edge neutron transmission

    CERN Document Server

    Santisteban, J R; Fitzpatrick, M E; Steuwer, A; Withers, P J; Daymond, M R; Johnson, M W; Rhodes, N; Schooneveld, E M

    2002-01-01

    The Bragg edges appearing in the transmitted time-of-flight spectra of polycrystalline materials have been recorded using a two-dimensional array of detectors. Subsequent analysis has enabled maps of the elastic strain to be produced.

  12. Decoherence phenomenon in X-ray diffraction and scattering from rough multilayers

    Science.gov (United States)

    Chernov, V. A.; Kondratiev, V. I.; Kovalenko, N. V.; Mytnichenko, S. V.; Zolotarev, K. V.

    2005-02-01

    High-resolution X-ray diffractometry was used to study the diffuse scattering from a series of rough multilayers. Reciprocal-space maps were obtained around the small- and wide-angle Bragg reflections using SR from the VEPP-3 storage ring. The data obtained reveal well-known quasi-Bragg diffuse-scattering sheets caused by conformal behavior of interfacial roughness as well as amplification of diffuse scattering when the incoming or outgoing angle is nearly equal to the Bragg angle (incoming and outgoing Bragg scattering) and when incoming and outgoing angles are nearly equal (quasi-specular diffuse scattering). The observed domination in intensity of the incoming Bragg features over outgoing ones, which demonstrates the breakdown of the reciprocity principle, is shown to reflect the decay rate of the coherent X-ray field through the diffuse-scattering channel, which becomes predominant as the spatial coherence of the incident X-ray beam increases. This diffuse-scattering behavior can be considered as a decoherence phenomenon inherent to open quantum systems.

  13. Decoherence phenomenon in X-ray diffraction and scattering from rough multilayers

    International Nuclear Information System (INIS)

    High-resolution X-ray diffractometry was used to study the diffuse scattering from a series of rough multilayers. Reciprocal-space maps were obtained around the small- and wide-angle Bragg reflections using SR from the VEPP-3 storage ring. The data obtained reveal well-known quasi-Bragg diffuse-scattering sheets caused by conformal behavior of interfacial roughness as well as amplification of diffuse scattering when the incoming or outgoing angle is nearly equal to the Bragg angle (incoming and outgoing Bragg scattering) and when incoming and outgoing angles are nearly equal (quasi-specular diffuse scattering). The observed domination in intensity of the incoming Bragg features over outgoing ones, which demonstrates the breakdown of the reciprocity principle, is shown to reflect the decay rate of the coherent X-ray field through the diffuse-scattering channel, which becomes predominant as the spatial coherence of the incident X-ray beam increases. This diffuse-scattering behavior can be considered as a decoherence phenomenon inherent to open quantum systems

  14. Principles of Bragg-Fresnel multilayer optics

    OpenAIRE

    Aristov, V. V.; Erko, A.I.; Martynov, V.V.

    1988-01-01

    The paper describes the principles and theoretical models of new X-ray optical elements based on the behaviour of Bragg-Fresnel diffraction. The use of volume diffraction permits one to achieve better spatial resolution compared with conventional plane optics and bending mirrors. The construction of Bragg-Fresnel elements combines the advantages of high-resolution Fresnel optics with stability of multilayer mirrors.

  15. Bragg diffraction of fermions at optical potentials

    International Nuclear Information System (INIS)

    This thesis describes the Bragg diffraction of ultracold fermions at an optical potential. A moving optical lattice was created, by overlaying two slightly detuned lasers. Atoms can be diffracted at this lattice if the detuning fulfills the Bragg condition for resting atoms. This Bragg diffraction is analyzed systematically in this thesis. To this end Rabi oscillations between the diffraction states were driven, as well in the weakly interacting Bragg regime, as in the strongly interacting Kapitza-Dirac regime. Simulations, based on a driven two-, respectively multilevel-system describe the observed effects rather well. Furthermore, the temporal evolution of the diffracted states in the magnetic trapping potential was studied. The anharmonicity of the trap in use and the scattering cross section for p-wave collisions in a 6Li system was determined from the movement of these states. Moreover the momentum distribution of the fermions was measured with Bragg spectroscopy and first signs of Fermi degeneracy were found. Finally an interferometer with fermions was build, exhibiting a coherence time of more than 100 μs. With this, the possibility for measurement and manipulation of ultracold fermions with Bragg diffraction could bee shown. (orig.)

  16. Reflectivity and Braggs Wavelength in FBG

    Directory of Open Access Journals (Sweden)

    Dinesh Arora, Dr.Jai Prakash, Hardeep Singh & Dr.Amit Wason

    2011-12-01

    Full Text Available We have presented an analytical model of splitters based on Fiber Bragg Grating used to detect a Braggwavelength from the number of wavelengths which are traveling in an optical fiber. The number of gridsand grating length can be used as a wavelength shifter. This paper presents experimental results that areused to show the effect of number of grids, the length of the grating on the Bragg wavelength andreflectivity of Fiber Bragg Grating (FBG. The pitch of grating is directly proportional to the grating lengthand inversely proportional to number of grids. When the grating length is fixed and the number of grids isincreased, the Bragg wavelength decreases resulting in increased reflectivity. This increased reflectivity isvery small. Further when the number of grids is kept constant and the grating length is increased theBragg wavelength increases. The effect of this increase in grating length on reflectivity is a very small. Inour model, the effectiveness of the grating in extracting the Braggs wavelength is nearly 100%.

  17. PUBLICATION OF ADMINISTRATIVE CIRCULAR

    CERN Multimedia

    HR Department

    2008-01-01

    ADMINISTRATIVE CIRCULAR NO. 23 (REV. 2) – SPECIAL WORKING HOURS Administrative Circular No. 23 (Rev. 2) entitled "Special working hours", approved following discussion in the Standing Concertation Committee meeting of 9 December 2008, will be available on the intranet site of the Human Resources Department as from 19 December 2008: http://cern.ch/hr-docs/admincirc/admincirc.asp It cancels and replaces Administrative Circular No. 23 (Rev. 1) entitled "Stand-by duty" of April 1988. A "Frequently Asked Questions" information document on special working hours will also be available on this site. Paper copies of this circular will shortly be available in departmental secretariats. Human Resources Department Tel. 78003

  18. Publication of administrative circular

    CERN Multimedia

    HR Department

    2009-01-01

    ADMINISTRATIVE CIRCULAR NO. 23 (REV. 2) – SPECIAL WORKING HOURS Administrative Circular No. 23 (Rev. 2) entitled "Special working hours", approved following discussion in the Standing Concertation Committee on 9 December 2008, will be available on the intranet site of the Human Resources Department as from 19 December 2008: http://cern.ch/hr-docs/admincirc/admincirc.asp It cancels and replaces Administrative Circular No. 23 (Rev. 1) entitled "Stand-by duty" of April 1988. A "Frequently Asked Questions" information document on special working hours will also be available on this site. Paper copies of this circular will shortly be available in Departmental Secretariats. Human Resources Department Tel. 78003

  19. Toroidal circular dichroism

    Science.gov (United States)

    Raybould, T. A.; Fedotov, V. A.; Papasimakis, N.; Kuprov, I.; Youngs, I. J.; Chen, W. T.; Tsai, D. P.; Zheludev, N. I.

    2016-07-01

    We demonstrate that the induced toroidal dipole, represented by currents flowing on the surface of a torus, makes a distinct and indispensable contribution to circular dichroism. We show that toroidal circular dichroism supplements the well-known mechanism involving electric dipole and magnetic dipole transitions. We illustrate this with rigorous analysis of the experimentally measured polarization-sensitive transmission spectra of an artificial metamaterial, constructed from elements of toroidal symmetry. We argue that toroidal circular dichroism will be found in large biomolecules with elements of toroidal symmetry and should be taken into account in the interpretation of circular dichroism spectra of organics.

  20. Mixing in Circular and Non-circular Jets in Crossflow

    DEFF Research Database (Denmark)

    Salewski, Mirko; Stankovic, D.; Fuchs, L.

    2008-01-01

    are compared for circular, elliptic, and square nozzles. For the latter configurations, effects of orientation are considered. The computations reveal that the distribution of a passive scalar in a cross-sectional plane can be single- or double-peaked, depending on the nozzle shape and orientation. A proper...... orthogonal decomposition of the transverse velocity indicates that coherent structures may be responsible for this phenomenon. Nozzles which have a single-peaked distribution have stronger modes in transverse direction. The global mixing performance is superior for these nozzle types. This is the case...... for the blunt square nozzle and for the elliptic nozzle with high aspect ratio. It is further demonstrated that the flow field contains large regions in which a passive scalar is transported up the mean gradient (counter-gradient transport) which implies failure of the gradient diffusion hypothesis....

  1. Anomalous behavior of neutron refraction index in a perfect crystal near the Bragg reflex

    International Nuclear Information System (INIS)

    Anomalous behavior of neutron refraction index in a perfect crystal near Bragg resonance was studied. This phenomenon is connected with the resonance behavior of potential of neutron interaction with crystal near the Bragg reflex. The amplitude of this resonance is equal to magnitude of g-harmonic of neutron interaction potential Vg and width is about the Bragg width of reflex. Recently, it was shown that for the case of noncentrosymmetric crystal this effect result in a large electric field acting on a neutron (value of the field can reach about 108V/cm) . This effect is planed using to search for the electric dipole moment of a neutron. If the degree of crystal imperfect is less than the Bragg reflection width (case of perfect crystal) the width of the reflex is determined by the own width of crystal reflex that is about 10−5 of the neutron energy. The value of g-harmonics of interaction of neutron with crystal Vg and optical potential of the interaction of neutron with crystal V0 are usually about the same. Therefore the variation of neutron energy on a 10−5 of its value will change significantly a potential of neutron interaction with crystal

  2. The Circular Camera Movement

    DEFF Research Database (Denmark)

    Hansen, Lennard Højbjerg

    2014-01-01

    It has been an accepted precept in film theory that specific stylistic features do not express specific content. Nevertheless, it is possible to find many examples in the history of film in which stylistic features do express specific content: for instance, the circular camera movement is used...... circular camera movement. Keywords: embodied perception, embodied style, explicit narration, interpretation, style pattern, television style...

  3. Perfect Circular Dichroic Metamirrors

    CERN Document Server

    Wang, Zuojia; Liu, Yongmin

    2015-01-01

    In nature, the beetle Chrysina gloriosa derives its iridescence by selectively reflecting left-handed circularly polarized light only. Here, for the first time, we introduce and demonstrate the optical analogue based on an ultrathin metamaterial, which we term circular dichroic metamirror. A general method to design the circular dichroic metasmirror is presented under the framework of Jones calculus. It is analytically shown that the metamirror can be realized by two layers of anisotropic metamaterial structures, in order to satisfy the required simultaneous breakings of n-fold rotational (n>2) and mirror symmetries. We design an infrared metamirror, which shows perfect reflectance for left-handed circularly polarized light without reversing its handedness, while almost completely absorbs right-handed circularly polarized light. These findings offer new methodology to realize novel chiral optical devices for a variety of applications, including polarimetric imaging, molecular spectroscopy, as well as quantum ...

  4. Aharonov-Bohm effect induced by circularly polarized light

    Science.gov (United States)

    Sigurdsson, H.; Kibis, O. V.; Shelykh, I. A.

    2015-11-01

    We demonstrated theoretically that the strong electron interaction with circularly polarized photons in ring-like nanostructures changes the phase of electron wave. This optically-induced effect is caused by the breaking of time-reversal symmetry and is similar to the Aharonov-Bohm effect. As a consequence of this phenomenon, the conductance of mesoscopic rings irradiated by a circularly polarized electromagnetic wave behaves as an oscillating function of the intensity and frequency of the wave.

  5. Fiber Bragg Grating Filter High Temperature Sensors

    Science.gov (United States)

    Lyons, Donald R.; Brass, Eric D.; Pencil, Eric (Technical Monitor)

    2001-01-01

    We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

  6. Edge-emitting diode lasers with narrow circular beam output

    Science.gov (United States)

    Wang, Lijie; Tong, Cunzhu; Zeng, Yugang; Ning, Yongqiang; Wang, Lijun

    2015-05-01

    We report near circular beam output from 808 nm edge-emitting diode lasers based on Bragg reflection waveguide design. Increasing quantum well number combined with reducing defect layer index and thickness was used to achieve high power output and extremely low vertical far field divergence. The TQW-BRLs achieve the lowest vertical divergence of 4.91° (full width at half maximum) and 9.8° (95% power). The maximum power of 4.6 W was achieved in the mounted DQW-BRL device under continuous-wave operation, being limited by thermal rollover.

  7. Circular statistics in R

    CERN Document Server

    Pewsey, Arthur; Ruxton, Graeme D

    2013-01-01

    Circular Statistics in R provides the most comprehensive guide to the analysis of circular data in over a decade. Circular data arise in many scientific contexts whether it be angular directions such as: observed compass directions of departure of radio-collared migratory birds from a release point; bond angles measured in different molecules; wind directions at different times of year at a wind farm; direction of stress-fractures in concretebridge supports; longitudes of earthquake epicentres or seasonal and daily activity patterns, for example: data on the times of day at which animals are c

  8. Results from a Bragg Curve Spectrometer

    International Nuclear Information System (INIS)

    The Bragg Curve Spectrometer (BCS) is an ionization chamber long enough to stop particles of interest. Particles enter through the cathode window and leave an ionization track parallel to the electric field. The ionization electrons drift through a Frisch grid and are collected on an anode. The anode current, as a function of time, is split and used as input for two amplifiers, one with a long integration time constant for energy measurement, and one with a short time constant to pick off the maximum ionization or Bragg peak. The Bragg peak, which is proportional to the nuclear charge, is used for particle identification. We have constructed and tested several versions of the BCS. The results are described

  9. Results from a Bragg curve spectrometer

    Science.gov (United States)

    Leach, D. D.; Davis, K. J.

    The Bragg Curve Spectrometer (BCS) is an ionization chamber long enough to stop particles of interest. Particles enter through the cathode window and leave an ionization track parallel to the electric field. The ionization electrons drift through a Frisch grid and are collected on an anode. The anode current, as a function of time, is split and used as input for two amplifiers, one with a long integration time constant for energy measurement, and one with a short time constant to pick off the maximum ionization or Bragg peak. The Bragg peak, which is proportional to the nuclear charge, is used for particle identification. Several versions of the BCS have been constructed and tested. The results are described.

  10. POLICRYPS-based electrically switchable Bragg reflector.

    Science.gov (United States)

    De Sio, Luciano; Tabiryan, Nelson; Bunning, Timothy J

    2015-12-14

    The formation and characterization of a switchable volume reflective element fabricated from a polymer liquid crystal (LC) polymer slice (POLICRYPS) structure by holographic photopolymerization at high temperature (65 °C) using a photosensitive/nematic liquid crystal prepolymer mixture is reported. The submicron Bragg structure formed consists of periodic continuous polymeric walls separated by periodic LC channels. The phase separated NLC self-aligns in a homeotropic alignment between the polymer walls as indicated by polarizing optical microscopy analysis (Maltese cross). The resulting periodic grating structure results in a Bragg reflection notch upon illumination with white light due to the periodic variation in refractive index. Electro-optical experiments realized through in-plane electrodes and temperature experiments confirm that the multilayer structure acts as a Bragg mirror whose reflection efficiency can be controlled by either a small (~3V/µm) electric field or temperature. PMID:26699059

  11. Circularly polarized light emission from semiconductor planar chiral nanostructures.

    Science.gov (United States)

    Konishi, Kuniaki; Nomura, Masahiro; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko; Kuwata-Gonokami, Makoto

    2011-02-01

    We demonstrate circularly polarized light emission from InAs quantum dots embedded in the waveguide region of a GaAs-based chiral nanostructure. The observed phenomenon originates due to a strong imbalance between left- and right-circularly polarized components of the vacuum field and results in a degree of polarization as high as 26% at room temperature. A strong circular anisotropy of the vacuum field modes inside the chiral nanostructure is visualized using numerical simulation. The results of the simulation agree well with experimental results. PMID:21405435

  12. Aloneness and the Isakower phenomenon.

    Science.gov (United States)

    Peterson, C A

    1992-01-01

    Under the sway of the oedipal imperative, the Isakower phenomenon has long been regarded as a regressive perceptual defense against castration anxiety accompanying incestuous wishes, often stimulated by primal scene exposure-fantasy. Clinical material from the psychoanalytic psychotherapy of a borderline patient with object constancy deficits is offered to support a reconceptualization of the Isakower phenomenon: Following annihilatory rage and the destruction of extant inner objects, resulting in a regression to the "drive organization of memory," the face-breast imagery within the Isakower phenomenon arrives as a hallucinatory alternative to unbearable aloneness. PMID:1607306

  13. BRAGG-FRESNEL OPTICS AND SUPERMIRRORS

    OpenAIRE

    A. Erko; Vidal, B.

    1996-01-01

    The main principles and some applications of Bragg-Fresnel multilayer optics and X-ray supermirrors are described. An elliptical Bragg-Fresnel multilayer lens (BFML), designed and fabricated in the IMT RAS has been used for 2-dimensional focusing of the white X-ray synchrotron beam. For the beam energy of about 12 KeV the spot size checked with the knife edge method was about 1 mm. Applications of BFML and supermirrors in x-ray imaging are discussed.

  14. Sangac interferometer on the holographic bragg grating

    CERN Document Server

    Tikhonov, E A

    2015-01-01

    The ring interferometer with zero optical path difference known as Sagnac one is offered with a diffraction splitting of the entering light beam. As the beamsplitter, a transmission holographic Bragg grating is used. Conditions of normal operation of this interferometer achieve under the equal intensity of beam copies and the adjustable phase shift between them in its two interferometer shoulders. These conditions are met with the holographic grating, which provides the phase shift 180^0 on the central Bragg wavelength. Experimental approbation of the modified interferometer validates the expected results.

  15. [Methylphenidate and secondary Raynaud's phenomenon].

    Science.gov (United States)

    Iglesias Otero, M; Portela Romero, M; Bugarín González, R; Ventura Victoria, M A

    2013-09-01

    Raynaud's phenomenon is a clinical disease characterized by episodic attacks of vasoconstriction of the arteries and arterioles of the extremities such as fingers and toes, sometimes the ears and nose, in response to cold or emotional stimuli. A classic attack is the pallor of the distal extremity, followed by cyanosis and redness, accompanied by paresthesia, usually as heat. When it occurs without apparent cause is called primary Raynaud's phenomenon. When associated with other disease, is called secondary Raynaud's phenomenon. The secondary table is associated with increased frequency of rheumatic diseases of collagen. They can also present certain drugs that cause vasoconstriction, such as ergotamine, beta-adrenergic antagonists, contraception and sympathomimetic drugs. Regarding the latter, we present a case of Raynaud's phenomenon secondary to methylphenidate in a 14 years. PMID:24034762

  16. A neural network for the Bragg synthetic curves recognition

    International Nuclear Information System (INIS)

    A ionization chamber was employed named Bragg curve spectroscopy. The Bragg peak amplitude is a monotone growing function of Z, which permits to identify elements through their measurement. A better technique for this measurement is to improve the use of neural networks with the purpose of the identification of the Bragg curve. (Author)

  17. Femtosecond laser pulse written Volume Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Richter Daniel

    2013-11-01

    Full Text Available Femtosecond laser pulses can be applied for structuring a wide range of ransparent materials. Here we want to show how to use this ability to realize Volume-Bragg-Gratings in various- mainly non-photosensitive - glasses. We will further present the characteristics of the realized gratings and a few elected applications that have been realized.

  18. Modal analysis of Bragg onion resonators

    OpenAIRE

    Xu, Yong; Liang, Wei; Yariv, Amnon; Fleming, James G.; Lin, Shawn-Yu

    2004-01-01

    From analysis of the high Q modes in a Bragg onion resonator with an omnidirectional reflector cladding, we establish a close analogy between such a resonator and a spherical hollow cavity in perfect metal. We demonstrate that onion resonators are ideal for applications that require a large spontaneous-emission factor ß, such as thresholdless lasers and single-photon devices.

  19. Efficient iterative technique for designing bragg gratings

    DEFF Research Database (Denmark)

    Plougmann, Nikolai; Kristensen, Martin

    2004-01-01

    We present a new iterative method for designing Bragg gratings based on the Levenberg-Marquardt method of minimizing a chi-squared merit function. It is effective for designing both weak and strong gratings and is particularly well suited for unchirped gratings....

  20. Compact waveguide circular polarizer

    Energy Technology Data Exchange (ETDEWEB)

    Tantawi, Sami G.

    2016-08-16

    A multi-port waveguide is provided having a rectangular waveguide that includes a Y-shape structure with first top arm having a first rectangular waveguide port, a second top arm with second rectangular waveguide port, and a base arm with a third rectangular waveguide port for supporting a TE.sub.10 mode and a TE.sub.20 mode, where the end of the third rectangular waveguide port includes rounded edges that are parallel to a z-axis of the waveguide, a circular waveguide having a circular waveguide port for supporting a left hand and a right hand circular polarization TE.sub.11 mode and is coupled to a base arm broad wall, and a matching feature disposed on the base arm broad wall opposite of the circular waveguide for terminating the third rectangular waveguide port, where the first rectangular waveguide port, the second rectangular waveguide port and the circular waveguide port are capable of supporting 4-modes of operation.

  1. Characteristics of light polarization in magneto-optic fiber Bragg gratings with linear birefringence

    Institute of Scientific and Technical Information of China (English)

    Baojian Wu; Chongzhen Li; Kun Qiu; Liwei Cheng

    2011-01-01

    @@ The coupling between guided optical waves in magneto-optic fiber Bragg gratings (MFBGs) with linear birefringence is investigated using the eigen-mode and coupled-mode approaches. The relationship between the polarization-dependent loss (PDL) and the eigen states of polarization (SOPs) in the MFBGs is discussed. Only the MFBGs with low linear birefringence are applied to the peak PDL-based magnetic field measurement, after which the linear dynamic range is determined using the relative magnitude of linear and magnetically induced circular birefringence. In this letter, a theoretical model is presented to explain the experimental results and help develop novel MFBG-based devices.%The coupling between guided optical waves in magneto-optic fiber Bragg gratings (MFBGs) with linear birefringence is investigated using the eigen-mode and coupled-mode approaches. The relationship between the polarization-dependent loss (PDL) and the eigen states of polarization (SOPs) in the MFBGs is discussed. Only the MFBGs with low linear birefringence are applied to the peak PDL-based magnetic field measurement, after which the linear dynamic range is determined using the relative magnitude of linear and magnetically induced circular birefringence. In this letter, a theoretical model is presented to explain the experimental results and help develop novel MFBG-based devices.

  2. Multilayer optical elements for generation and analysis of circularly polarized x-rays

    International Nuclear Information System (INIS)

    Calculations of the relative phase changes of σ and π electric field components on Bragg reflection from and transmission through multilayers are presented. Large relative phase changes can be calculated in certain cases, which may lead to utility of multilayers as quarter-wave plates for generation and analysis of circularly polarized soft x-radiation. Similar behavior may be expected for perfect crystals in the hard x-ray range. 24 refs., 4 figs

  3. Resurrecting Dead-water Phenomenon

    CERN Document Server

    Mercier, Matthieu; Dauxois, Thierry

    2011-01-01

    We revisit experimental studies performed by Ekman on dead-water using modern techniques in order to present new insights on this peculiar phenomenon. We extend its description to more general situations such as a three-layer fluid or a linearly stratified fluid in presence of a pycnocline, showing the robustness of dead-water phenomenon. We observe large amplitude nonlinear internal waves which are coupled to the boat dynamics, and we emphasize that the modeling of the wave-induced drag requires more analysis, taking into account nonlinear effects.

  4. A rare phenomenon: oculonasal synkinesis.

    Science.gov (United States)

    Ciloglu, N Sinem; Duran, Alpay; Buyukdogan, Hasan

    2014-10-01

    Oculonasal synkinesis is the simultaneous contraction of the orbicularis oculi and the compressor narium minor muscles. The etiology of this phenomenon is still unclear; congenital and traumatic reasons are considered to be responsible. Here we report a case of oculonasal synkinesis. PMID:25015551

  5. Is consciousness a nonspatial phenomenon?.

    OpenAIRE

    Gundersen, Ståle

    2011-01-01

    Colin McGinn has argued that consciousness is a nonspatial phenomenon. McGinn’s arguments for the nonspatiality of consciousness are presented and then criticized. It is concluded that consciousness may be as spatial as electric charge and different kinds of abilities.

  6. Translation as a Psycholinguistic Phenomenon

    Science.gov (United States)

    Zasyekin, Serhiy

    2010-01-01

    The article sketches the outlines of a theoretical framework for the analysis of translation of literary texts, viewed as psycho-semiotic phenomenon and based on evaluation of earlier attempts in this direction, and on the results of a psycholinguistic empirical study of translations. Central to this framework is the recent insight that the human…

  7. Plasmonic Fano interference produced by gold nano-disks on a dielectric Bragg stack

    Science.gov (United States)

    Hajebifard, Akram; Berini, Pierre

    2015-09-01

    Fano interference is predicted in a structure consisting of a periodic array of uncoupled gold nano-disks (AuNDs) supported by a Bragg stack. The phenomenon occurs due to resonant interference between the reflection spectrum of the Bragg stack and localized surface plasmon resonances (LSPRs) on the AuNDs. Fitting the computational results to the Fano lineshape formula yields the Fano parameters of the resonances including their linewidth. One of the most important advantages of the structure is that the linewidth of the Fano resonances (˜9 nm) is much narrower than the bandwidth of the LSPR nano-disks (˜80 nm) and the reflection bandwidth of the Bragg stack on which the disks are supported (˜100 nm). The narrow Fano linewidth and the ease with which they can be interrogated using perpendicularly incident light makes the structure attractive for biosensing applications. The bulk sensitivities and figure of merit of Fano resonances in a proposed design are 44 nm/RIU (redshift) and -52 nm/RIU (blueshift), and ˜4 RIU-1, respectively.

  8. Wiimote Experiments: Circular Motion

    Science.gov (United States)

    Kouh, Minjoon; Holz, Danielle; Kawam, Alae; Lamont, Mary

    2013-01-01

    The advent of new sensor technologies can provide new ways of exploring fundamental physics. In this paper, we show how a Wiimote, which is a handheld remote controller for the Nintendo Wii video game system with an accelerometer, can be used to study the dynamics of circular motion with a very simple setup such as an old record player or a…

  9. Ground effects on magnetooptic Bragg cells

    Institute of Scientific and Technical Information of China (English)

    WEN Feng; WU BaoJian; QIU Kun

    2008-01-01

    Propagation equation of magnetostatic waves in an arbitrarily magnetized yttrium-iron-garnet/gadolinium-gallium-garnet waveguide coated with perfect metal planes is obtained using the method of the surface magnetic permeability. And ground effects on magnetooptic Bragg cells are investigated with the magnetooptic coupled-mode theory. Theoretical analysis indicates that, diffraction efficiency of guided optical waves can be improved by adjusting the spacing of the metal plane from the ferrite film, and ground effects on the diffraction efficiency will be enhanced using an appropriately tilted bias magnetic field. In the metal clad waveguide system, the magnetostatic wave frequency at which the diffraction efficiency peak is obtained corresponds to the "zero-dispersion" point. Performance of RF spectrum analyzers in this system can also be improved by comparing with the case of the sandwich waveguide. Therefore, magnetooptic Bragg cells with the metal clad waveguide are potential applications to the microwave communication and optical signal processing.

  10. Ion implanted Bragg endash Fresnel lens

    International Nuclear Information System (INIS)

    We have investigated the feasibility of widening the bandpath of the Bragg endash Fresnel optical element through the use of ion implantation. The focusing properties of Bragg endash Fresnel lenses (BFLs) were studied as a function of the implantation dose and energy. An enhancement of the focus intensity of up to 15% was found, which is less than expected. Due to the complicated scattering of the low energy ions inside the micrometer- and submicrometer-sized crystal features that make up the BFL relief, the implantation technology destroys the peripheral zones of the BFL more than it increases the intensity in the focus. Nevertheless we believe that high energy implantation can be successfully used to modify the BFL reflectivity, especially in the case of nearly backscattering reflection. copyright 1996 American Institute of Physics

  11. Bragg Curve Counter for primary beam monitor

    International Nuclear Information System (INIS)

    The prototype Bragg Curve Counter (BCC) has been tested by α-source (241Am) with a continuous gas flow system (P-10: 90% Ar+10% CH4, at 300Torr). Two types of the Frisch grid were prepared for the BCC. One was made of expanded metal meshes, which consist of 175 meshes/inch2 with a 100μmt nickel sheet. The other was made of a 1mm pitch wire with φ 50 μm of the tungsten. The shape of Bragg peak signal was compared each other. It was found that the energy spectrum obtained by the wire grid is a little sharper than that obtained by the meshes grid. However the meshes grid is superior than the wire grid so far as handling and durability are concerned. (author)

  12. Sampled phase-shift fiber Bragg gratings

    Institute of Scientific and Technical Information of China (English)

    Xu Wang(王旭); Chongxiu Yu(余重秀); Zhihui Yu(于志辉); Qiang Wu(吴强)

    2004-01-01

    A phase-shift fiber Bragg grating (FBG) with sampling is proposed to generate a multi-channel bandpass filter in the background of multi-channel stopbands. The sampled noire fiber gratings are analyzed by Fourier transform theory first, and then simulation and experiment are performed, the results show that transmission peaks are opened in every reflective channel, the spectrum shape of every channel is identical.It can be used to fabricate multi-wavelength distributed feedback (DFB) fiber laser.

  13. Study on position sensitive Bragg detector

    International Nuclear Information System (INIS)

    A position sensitive Bragg Curve Spectroscopy (PS-BCS) for heavy ion identification is introduced. The position signal is extracted via an auxiliary grid (P grid) between the anode and the Frisch grid. The position is determined by the wires. The charge division method have been used for position read-out. The test results of the detector with 252Cf α source have shown a position resolution ΔX<9 mm

  14. Improvement of soybean variety 'Bragg' through mutagenesis

    International Nuclear Information System (INIS)

    Full text: Variety 'Bragg' (Jackson x D49-2491) of soybean (Glycine max. (L.) Merrill) was found to be high yielding and widely adaptable throughout India. Its yield stability, however, is unsatisfactory, probably due to low germinability necessitating use of higher seed rate. With the main objective to rectify this defect, mutagenesis involving chemical as well as physical mutagens was used. Dry seeds were treated with EMS or MMS (0.2, 0.4 and 0.6%), or gamma rays (15, 20 and 25 kR) with and without additional exposure to UV (2 hrs at 260 nm) in 1982. In M2, a mutation frequency ranging from 2.24 to 22.85% was observed. Screening of M2 and of subsequent generations yielded a broad spectrum of mutations. Some of the mutants are agronomically useful. Among them, mutant 'T214' resulting from 25 kR gamma rays + UV, was found to possess better germinability (+15%), earliness (5 days) and high yield during both rainy and post-rainy seasons in 1986 and 1987, when compared with the parent variety 'Bragg'. The mutant has smaller seed-size (TGW 125 g) than the parent (145 g). In soybean, large-seeded varieties were reported to have poorer seed germinability. Thus, the better germinability of the mutant might be related to its reduced seed size. Seeds of the mutant show a light brown colour of the hilum in contrast to the black hilum of 'Bragg'. In other characters the mutant is similar to 'Bragg'. The mutant should have potential for commercial cultivation in India. For confirmation of its agronomically superior performance, it is undergoing national evaluation in multilocational trials under 'All India Co-ordinated Research Project on Soybean (ICAR)'. The strain has been named 'NRC-2'. (author)

  15. Fort Bragg Embraces Groundbreaking Heat Pump Technology

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2013-03-01

    The U.S. Army’s Fort Bragg partnered with the Department of Energy (DOE) to develop and implement solutions to build new, low-energy buildings that are at least 50% below Standard 90.1-2007 of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), the American National Standards Institute (ANSI), and the Illuminating Engineering Society of North America (IESNA) as part of DOE’s Commercial Building Partnerships (CBP) Program.

  16. City as an Interdisciplinary Phenomenon

    Directory of Open Access Journals (Sweden)

    S. A. Riazi

    2013-01-01

    Full Text Available Interdisciplinary as a new approach to the problems of science and knowledge, has a wide range, but there is no consensus on its epistemological range and ontological domain. Among the different and various problems, there is a general agreement on “City” as a field of study as an interdisciplinary phenomenon. At least, three important disciplines, geography, architecture and social sciences, have engaged in analyzing this phenomenon by using each other’s methods, indicators, and objects. The extensive scientific branches of city have attracted the attentions of phenomenologists, engineers, economists, politicians, researchers of cultural studies, environment, and media. In this paper, the interdisciplinary aspect of city is reviewed by focusing on its connection with space, media, politics, economic and culture.

  17. An intriguing oscillating combustion phenomenon

    OpenAIRE

    Corbel, J.M.L.; van Lingen, J.N.J.; Zevenbergen, J.F.; Gijzeman, O.L.J.; Meijerink, A.

    2012-01-01

    Strobes are pyrotechnic compositions that emit bright flashes of white or colored light at regular time intervals. The strobe effect has applications in various fields, most notably in the fireworks industry and in the military area (signaling – missile decoys – crowd control). However, the chemical and physical mechanisms involved in this curious combustion phenomenon remain unknown. This study investigates parameters that influence the strobe effect (frequency, sharpness of flashes). Variat...

  18. TERRORISM AS A COMMUNICATION PHENOMENON

    OpenAIRE

    Atanesian, Arthur

    2009-01-01

    Some of the contemporary theories of the mass media and political communications teach their audiences and mold public ideas about events or phenomena which political forces exploit for their own ends. The media do not merely cover events or describe phenomena-they cover them with "outgrowths" that disfigure them to the extent that the public gradually shifts from discussing the real phenomenon to its virtual likeness, which might well be a product of media skills. This explains why from time...

  19. Entropy-driven cutoff phenomenon

    CERN Document Server

    Lancia, Carlo

    2011-01-01

    In this article we present a theorem relating the cutoff phenomenon for finite Markov chains to suitably chosen random times. We have in mind the generalization to systems with uniform stationary measure of the link between hitting times and cutoff. Such link has been already proved in literature only for systems with stationary measure concentrated in a finite region. We show some examples of application of our result.

  20. PHENOMENON OF CARVED DRIVING WHEELS

    Institute of Scientific and Technical Information of China (English)

    LI Xianghua; ZHANG Jianwu

    2007-01-01

    A newly found phenomenon of carved driving wheels of a rea-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions, which distribute regularly and uniformly. Everyday, the tractor tows a trailer which are times heavier than the tractor, and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation, which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer, the slip ratio of the tractor's driving wheels is very large. Therefore, there is severe torsional self-excited vibration in the tractor's drivetrain, and the self-excited vibration results in severe and regular fluctuations of the rear wheel's velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time, the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration, and this times explained the existence of three damaged regions. At last, it points out that the phenomenon can be avoided when the torsional damping is large enough.

  1. Circularity-Measuring System

    Science.gov (United States)

    WHIPPO. WALTER B.; Rohrkaste, G. R.; Miller, John E.

    1989-01-01

    Shape gauge and associated computer constitute system measuring deviations of large cylinders from roundness. Shaped and held somewhat like crossbow, measures relative locations of three points on surface of large, round object. By making connected series of measurements around periphery technician using gauge determines deviation of object from perfect circularity. Used to measure straightness, roundness, or complicated shapes of such large geometrical objects as surfaces of aircraft and hulls of ships.

  2. Circular arc structures

    KAUST Repository

    Bo, Pengbo

    2011-07-01

    The most important guiding principle in computational methods for freeform architecture is the balance between cost efficiency on the one hand, and adherence to the design intent on the other. Key issues are the simplicity of supporting and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where geometric complexity is concentrated in the nodes, we stay with smooth surfaces and rather distribute complexity in a uniform way by allowing edges in the shape of circular arcs. We are able to achieve the simplest possible shape of nodes without interfering with known panel optimization algorithms. We study remarkable special cases of circular arc structures which possess simple supporting elements or repetitive edges, we present the first global approximation method for principal patches, and we show an extension to volumetric structures for truly threedimensional designs. © 2011 ACM.

  3. Switchable circular beam deflectors

    Science.gov (United States)

    Shang, Xiaobing; Joshi, Pankaj; Tan, Jin-Yi; De Smet, Jelle; Cuypers, Dieter; Baghdasaryan, Tigran; Vervaeke, Michael; Thienpont, Hugo; De Smet, Herbert

    2016-04-01

    In this work, we report two types of electrically tunable photonic devices with circularly symmetric polarization independent beam steering performance (beam condensing resp. beam broadening). The devices consist of circular micro grating structures combined with nematic liquid crystal (LC) layers with anti-parallel alignment. A single beam deflector converts a polarized and monochromatic green laser beam (λ =543.5 nm) into a diffraction pattern, with the peak intensity appearing at the third order when 0~{{V}\\text{pp}} is applied and at the zeroth order (no deflection) for voltages above 30~{{V}\\text{pp}} . Depending on the shape of the grating structure (non-inverted or inverted), the deflection is inwards or outwards. Both grating types can be made starting from the same diamond-tooled master mold. A polarized white light beam is symmetrically condensed resp. broadened over 2° in the off state and is passed through unchanged in the on state. By stacking two such devices with mutually orthogonal LC alignment layers, polarization independent switchable circular beam deflectors are realized with a high transmittance (>80%), and with the same beam steering performance as the polarization dependent single devices.

  4. Recollision with circular polarization

    Science.gov (United States)

    Mauger, Francois; Kamor, Adam; Bandrauk, Andre; Chandre, Cristel; Uzer, Turgay

    2013-05-01

    Since its identification in the 90s, the recollision scenario has revealed to be very helpful in explaining many phenomena in atomic and molecular systems subjected to strong and short laser pulses, and it is now at the core of the strong field physics and attosecond science. For linearly polarized laser fields, the recollision scenario has been able to explain nonsequential double ionization (NSDI), high harmonic generation (HHG) and laser induced diffraction (LIED), just to cite them. The same scenario also predicts the absence of recollision when the field is circularly polarized, therefore leading to the absence of NSDI, HHG or LIED. Recently, the influence of the ellipticity of the laser has drawn an increasing level of interest in the strong field community as it is seen as a way to control the electronic dynamics and, for instance, HHG. Using classical models, the common belief of the absence of recollision with circularly polarized laser fields has been proven wrong. In my talk I will present classical and quantum evidence of the presence of recollision with circular polarization. I will discuss the conditions under which such recollisions happen and what they imply.

  5. AIDS as a social phenomenon.

    Science.gov (United States)

    Bennett, F J

    1987-01-01

    AIDS as a new lethal and at present incurable sexually transmitted disease is already having remarkable social repercussions not yet fully explicit and hence it can be termed a social phenomenon. Political, behavioural, economic and legal reactions and social responses such as stigmatization, changes in the sick role and the growth of voluntary organizations and international collaboration are described. Communication, education and information aspects of AIDS are considered using material from the press and it is clear that a massive educational approach to modify behaviour must be the basis for a control programme. PMID:3317877

  6. Melting of chiral order in terbium manganate (TbMnO3) observed with resonant x-ray Bragg diffraction

    OpenAIRE

    Lovesey, S W; Scagnoli, V.; Garganourakis, M; Koohpayeh, S. M.; Detlefs, C.; Staub, U

    2013-01-01

    Resonant Bragg diffraction of soft, circularly polarized x-rays has been used to observe directly the temperature dependence of chiral-order melting in a motif of Mn ions in terbium manganate. The underlying mechanism uses the b-axis component of a cycloid, which vanishes outside the polar phase. Melting is witnessed by the first and second harmonics of a cycloid, and we explain why the observed temperature dependence is different in the two harmonics. Our direct observation of melting is sup...

  7. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

  8. Spatially Resolved Analysis of Bragg Selectivity

    Directory of Open Access Journals (Sweden)

    Tina Sabel

    2015-11-01

    Full Text Available This paper targets an inherent control of optical shrinkage in photosensitive polymers, contributing by means of spatially resolved analysis of volume holographic phase gratings. Point by point scanning of the local material response to the Gaussian intensity distribution of the recording beams is accomplished. Derived information on the local grating period and grating slant is evaluated by mapping of optical shrinkage in the lateral plane as well as through the depth of the layer. The influence of recording intensity, exposure duration and the material viscosity on the Bragg selectivity is investigated.

  9. Status of the OCS Bragg-Spectrometer for SODART

    DEFF Research Database (Denmark)

    Wiebicke, H.J.; Halm, I.; Christensen, Finn Erland; Rasmussen, Inga; Rasmussen, H.E.

    OCS, the Bragg spectrometer for the SODART X-ray telescope onboard the SPECTRUM-RONTGEN-GAMMA (SRG) satellite has been completed. Preliminary results of his performance are presented.......OCS, the Bragg spectrometer for the SODART X-ray telescope onboard the SPECTRUM-RONTGEN-GAMMA (SRG) satellite has been completed. Preliminary results of his performance are presented....

  10. Status of the OCS Bragg-Spectrometer for SODART

    DEFF Research Database (Denmark)

    Wiebicke, H.J.; Halm, I.; Christensen, Finn Erland;

    1998-01-01

    OCS, the Bragg spectrometer for the SODART X-ray telescope onboard the SPECTRUM-RONTGEN-GAMMA (SRG) satellite has been completed. Preliminary results of his performance are presented.......OCS, the Bragg spectrometer for the SODART X-ray telescope onboard the SPECTRUM-RONTGEN-GAMMA (SRG) satellite has been completed. Preliminary results of his performance are presented....

  11. Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio; Nielsen, Kristian; Rasmussen, Henrik K.; Khan, L.; Webb, D.J.; Kalli, K.; Bang, Ole

    2011-01-01

    A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

  12. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

    This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

  13. Antennas on circular cylinders

    DEFF Research Database (Denmark)

    Knudsen, H. L.

    1959-01-01

    antenna in a circular cylinder. By a procedure similar to the one used by Silver and Saunders, expressions have been derived for the field radiated from an arbitrary surface current distribution on a cylinder surface coaxial with a perfectly conducting cylinder. The cases where the space between the two...... cylindrical surfaces have the sane characteristic constants and different constants are treated separately. Extensive numerical computations of the field radiated from the slot antennas described here are being carried out, but no numerical results are yet available...

  14. Translation as a psycholinguistic phenomenon.

    Science.gov (United States)

    Zasyekin, Serhiy

    2010-06-01

    The article sketches the outlines of a theoretical framework for the analysis of translation of literary texts, viewed as psycho-semiotic phenomenon and based on evaluation of earlier attempts in this direction, and on the results of a psycholinguistic empirical study of translations. Central to this framework is the recent insight that the human cerebral hemisphere functional asymmetry somehow plays a role in structuring the fictional text by its author and in its processing by the interpreter. It is argued that the texts of modernism and post-modernism contain information blocks describing a character's perception of events in altered states of consciousness. This model helps to explain how a translator's inappropriate linguistic choice may influence the target language reader's aesthetic reaction. PMID:19894118

  15. Fano resonances in integrated silicon Bragg reflectors for sensing applications.

    Science.gov (United States)

    Chang, Chia-Ming; Solgaard, Olav

    2013-11-01

    We investigate theoretically and experimentally Fano resonances in integrated silicon Bragg reflectors. These asymmetric resonances are obtained by interference between light reflected from the Bragg waveguide and from the end facet. The Bragg reflectors were designed and modeled using the 1D transfer matrix method, and they were fabricated in standard silicon wafers using a CMOS-compatible process. The results show that the shape and asymmetry of the Fano resonances depend on the relative phase of the reflected light from the Bragg reflectors and end facet. This phase relationship can be controlled to optimize the lineshapes for sensing applications. Temperature sensing in these integrated Bragg reflectors are experimentally demonstrated with a temperature sensitivity of 77 pm/°C based on the thermo-optic effect of silicon. PMID:24216944

  16. Nonlinear light propagation in cholesteric liquid crystals with a helical Bragg microstructure

    CERN Document Server

    Liu, Yikun; Zhu, Xing; Xie, Xiangsheng; Feng, Mingneng; Zhou, Jianying; Li, Yongyao; Xiang, Ying; Malomed, Boris A; Kurizki, Gershon

    2015-01-01

    Nonlinear optical propagation in cholesteric liquid crystals (CLC) with a spatially periodic helical molecular structure is studied experimentally and modeled numerically. This periodic structure can be seen as a Bragg grating with a propagation stopband for circularly polarized light. The CLC nonlinearity can be strengthened by adding absorption dye, thus reducing the nonlinear intensity threshold and the necessary propagation length. As the input power increases, a blue shift of the stopband is induced by the self-defocusing nonlinearity, leading to a substantial enhancement of the transmission and spreading of the beam. With further increase of the input power, the self-defocusing nonlinearity saturates, and the beam propagates as in the linear-diffraction regime. A system of nonlinear couple-mode equations is used to describe the propagation of the beam. Numerical results agree well with the experiment findings, suggesting that modulation of intensity and spatial profile of the beam can be achieved simult...

  17. Electrically controlled Bragg resonances of an ambichiral electro-optic structure: oblique incidence

    CERN Document Server

    Dixit, Mukul

    2007-01-01

    The Pockels effect can increase the effective birefringence of ambichiral, electro--optic rejection filters made of materials with a $\\bar{4}2m$ point group symmetry, when a dc electric field is applied parallel to the axis of nonhomogeneity. The reflectances and the transmittances of such an ambichiral structure for obliquely incident plane waves is solvable through a boundary-value problem that is formulated using the frequency-domain Maxwell equations, the constitutive equations that contain the Pockels effect, and standard algebraic techniques for handling 4x4 matrix ordinary differential equations. The Bragg resonance peaks, for different circular-polarized-incidence conditions, blueshift as the angle of incidence increases. These blueshifts are unaffected by the sign of the dc electric field.

  18. Pi, Archimedes and circular splines

    OpenAIRE

    Sablonnière, Paul

    2013-01-01

    In the present paper, we give approximate values of $\\pi$ deduced from the areas of inscribed and circumscribed quadratic and cubic circular splines. Similar results on circular splines of higher degrees and higher approximation orders can be obtained in the same way. We compare these values to those obtained by computing the {\\em perimeters} of those circular splines. We observe that the former are much easier to compute than the latter and give results of the same order. It also appears tha...

  19. Deixis as a symbolic phenomenon

    Directory of Open Access Journals (Sweden)

    West, Donna E.

    2011-01-01

    Full Text Available Children's early development of demonstrative use emanates directly from indexical gestures, namely, eye gaze, pointing, prehensile reaching, and giving exchanges. These indexical gestures become social in that they are joint attentional, and mark the inception of deictic use. Although children's deictic use draws upon index as a directional and social phenomenon, early uses of index alone do not deliver any semantic/lexical/symbolic determinants to the mix. The distinctive premise here is that deictics, especially demonstratives, are not merely social, but symbolic from a Peircian perspective, especially in light of developmental findings (West 1986, 1987, 2010; Tanz 2009 indicating an acquisitional pattern of non-contrastive to contrastive uses of "this" and "that" from 3;0–4;9. While initial non-contrastive uses of demonstratives are directional and/or social, contrastive use after 3;0 requires apprehension of symbolic role taking/role shifting. In addition to delivering the indexical and/or social, deictic indicators must implicitly refer to a class (Nunberg 1993, 1995, e.g., near/far objects from speaker's perspective in the case of demonstratives, and must ultimately have the potential to contrast objects/places with respect to distinctive points of orientation. These components together illustrate how mastery of deictic indicators is both a socio-pragmatic and semantic enterprise. In addition to indexing objects and securing joint attention with gesture, deixis requires semiotic and semantically based orientational competencies to shift perspectives and speech situation roles.

  20. The phenomenon of Soviet science.

    Science.gov (United States)

    Kojevnikov, Alexei

    2008-01-01

    The grand "Soviet experiment" constituted an attempt to greatly accelerate and even shortcut the gradual course of historical development on the assumption of presumed knowledge of the general laws of history. This paper discusses the parts of that experiment that directly concerned scientific research and, in fact, anticipated or helped define important global changes in the functioning of science as a profession and an institution during the twentieth century. The phenomenon of Soviet, or socialist, science is analyzed here from the comparative international perspective, with attention to similarities and reciprocal influences, rather than to the contrasts and dichotomies that have traditionally interested cold war-type historiography. The problem is considered at several levels: philosophical (Soviet thought on the relationship between science and society and the social construction of scientific knowledge); institutional (the state recognition of research as a separate profession, the rise of big science and scientific research institutes); demographic (science becoming a mass profession, with ethnic and gender diversity among scientists); and political (Soviet-inspired influences on the practice of science in Europe and the United States through the social relations of science movement of the 1930s and the Sputnik shock of the 1950s). PMID:18831319

  1. Circular PVDF Airborne Transducer

    Institute of Scientific and Technical Information of China (English)

    JIAO Li-hua; XU Li-mei; HONG Hu

    2007-01-01

    With the required increased audio pressure of the parametric ultrasonic transducer array and the difficulty to theoretically analyse the complex ultrasonic structure in audio beam application, an computafionally efficient model is desired to describe the characteristic of the parametric ultrasonic transducer array for the system design and optimization. By applying the symmetry boundary conditions at the mid-plane in the thickness direction, a finite element model based on the half thickness simplification is presented to analyze the parametric circular transducer which is designed by gluing the poly Vinylidene fluoride film (PVDF). The validity of the proposed model is confirmed by a comparison of finite element aalysis results with the theoretical value and experimental data, which show that they are making a good agreement with each other.

  2. Operational circular No. 1 (Rev. 1) – Operational circulars

    CERN Multimedia

    HR Department

    2011-01-01

    Operational Circular No. 1 (Rev. 1) is applicable to members of the personnel and other persons concerned. Operational Circular No. 1 (Rev. 1) entitled "Operational circulars", approved following discussion at the Standing Concertation Committee meeting on 4 May 2011, is available on the intranet site of the Human Resources Department: https://hr-docs.web.cern.ch/hr-docs/opcirc/opcirc.asp It cancels and replaces Operational Circular No. 1 entitled "Operational Circulars” of December 1996. This new version clarifies, in particular, that operational circulars do not necessarily arise from the Staff Rules and Regulations, and the functional titles have been updated to bring them into line with the current CERN organigram. Department Head Office  

  3. Research of fiber Bragg grating geophone based on cantilever beam

    Science.gov (United States)

    Wang, Liang; Chen, Shao-hua; Tao, Guo; Lu, Gui-wu; Zhao, Kun

    2009-07-01

    Along with the development of seismic exploration, the demand of frequency, dynamic range, precision and resolution ration is increased. However, the traditional geophone has disadvantages of narrower bandwidth, lower dynamic range and resolution, and cannot meet the new needs of seismic exploration. Geophone technology is a choke point, which constrains the development of petroleum prospecting in recent years. Fiber Bragg Grating seism demodulation technology is the newest kind of seism demodulation technology. The sensing probe of the Fiber Bragg Grating geophone is made up of Fiber Bragg Gating. The information which it collects is embodied by wavelength. The modulation-demodulation is accomplished by Fiber Bragg Gating geophone directly. In this paper, we design different size Fiber Bragg Grating geophones based on the transmission properties of Fiber Bragg Grating and cantilever beam method. Beryllium bronze and stainless steel are chosen as the elastic beam and shell materials, respectively. The parameters such as response function and sensitivity are given theoretically. In addition, we have simulated the transmission characteristics of Fiber Bragg Grating geophone by virtue of finite element analysis. The influences of wavelength, mass block, fiber length on the characteristics of geophones are discussed in detail, and finally the appropriate structural parameters are presented.

  4. Frequency shift of the Bragg and Non-Bragg backscattering from periodic water wave.

    Science.gov (United States)

    Wen, Biyang; Li, Ke

    2016-01-01

    Doppler effect is used to measure the relative speed of a moving target with respect to the radar, and is also used to interpret the frequency shift of the backscattering from the ocean wave according to the water-wave phase velocity. The widely known relationship between the Doppler shift and the water-wave phase velocity was deduced from the scattering measurements data collected from actual sea surface, and has not been verified under man-made conditions. Here we show that this ob- served frequency shift of the scattering data from the Bragg and Non-Bragg water wave is not the Doppler shift corresponding to the water-wave phase velocity as commonly believed, but is the water-wave frequency and its integral multiple frequency. The power spectrum of the backscatter from the periodic water wave consists of serials discrete peaks, which is equally spaced by water wave frequency. Only when the water-wave length is the integer multiples of the Bragg wave, and the radar range resolution is infinite, does the frequency shift of the backscattering mathematically equal the Doppler shift according to the water-wave phase velocity. PMID:27531469

  5. A ballistic motion disrupted by Bragg reflections

    CERN Document Server

    Clark, Jeremy Thane

    2012-01-01

    I study a Lindblad dynamics modeling a quantum test particle in a Dirac comb that collides with particles from a background gas. The main result is a homogenization theorem in a semi-classical limiting regime involving large mass for the test particle and a rescaling for the strength and period of the Dirac comb. Over the time interval considered, the particle would exhibit essentially ballistic motion if either the singular periodic potential or the kicks from the gas were removed. However, the particle behaves diffusively when both sources of forcing are present. The conversion of the motion from ballistic to diffusive is generated by occasional Bragg reflections that result when the test particle's momentum is driven through a collision near an element of the half-spaced reciprocal lattice of the Dirac comb.

  6. Fiber Bragg gratings for microwave photonics subsystems.

    Science.gov (United States)

    Wang, Chao; Yao, Jianping

    2013-09-23

    Microwave photonics (MWP) is an emerging filed in which photonic technologies are employed to enable and enhance functionalities in microwave systems which are usually very challenging to fulfill directly in the microwave domain. Various photonic devices have been used to achieve the functions. A fiber Bragg grating (FBG) is one of the key components in microwave photonics systems due to its unique features such as flexible spectral characteristics, low loss, light weight, compact footprint, and inherent compatibility with other fiber-optic devices. In this paper, we discuss the recent development in employing FBGs for various microwave photonics subsystems, with an emphasis on subsystems for microwave photonic signal processing and microwave arbitrary waveform generation. The limitations and potential solutions are also discussed. PMID:24104174

  7. Phase transition between the Bragg Glass and a disordered Phase in Nb3Sn, detected by 3rd harmonics of the AC magnetic susceptibility

    OpenAIRE

    Adesso, Maria G.; Uglietti, Davide; Flukiger, Rene; Polichetti, Massimiliano; Pace, Sandro

    2005-01-01

    We report additional experimental evidences about the presence of an universal behavior in the Field-Temperature Phase Diagram of Type II Superconductors. This behavior is characterized by a phase transition in the vortex matter between the disordered and the Bragg Glass phase. The experimental detection of a Peak Effect phenomenon has been proved to be strictly connected to the existence of this phase transition. In this paper, we show the first observation of a Peak Effect in the compound N...

  8. Solgel grating waveguides for distributed Bragg reflector lasers.

    Science.gov (United States)

    Fardad, M A; Luo, H; Beregovski, Y; Fallahi, M

    1999-04-01

    Solgel grating waveguides and their application to the fabrication of external-cavity distributed Bragg reflector (DBR) lasers are demonstrated. A new composition of aluminosilicate material is developed for the fabrication of single-mode waveguides and Bragg reflectors. An average loss of <0.2 dB/cm is measured in the single-mode waveguides at 1550 nm. The reflectors show filtering greater than 97% near 1530 nm, with a bandwidth of ~0.6 nm . The Bragg reflectors are used as feedback resonators for DBR lasers. Single-mode lasing with a sidemode suppression of better than 25 dB is demonstrated. PMID:18071539

  9. Modeling Component-based Bragg gratings Application: tunable lasers

    Directory of Open Access Journals (Sweden)

    Hedara Rachida

    2011-09-01

    Full Text Available The principal function of a grating Bragg is filtering, which can be used in optical fibers based component and active or passive semi conductors based component, as well as telecommunication systems. Their ideal use is with lasers with fiber, amplifiers with fiber or Laser diodes. In this work, we are going to show the principal results obtained during the analysis of various types of grating Bragg by the method of the coupled modes. We then present the operation of DBR are tunable. The use of Bragg gratings in a laser provides single-mode sources, agile wavelength. The use of sampled grating increases the tuning range.

  10. X-ray diffraction at Bragg angles around π/2

    International Nuclear Information System (INIS)

    X-ray diffraction at Bragg angles around π/2 is studied from the theoretical and experimental points of view. The proposed corrections to the dynamical theory in the θβ ≅ π/2 cases, has been reviewed showing the equivalence between two formalisms leading to a corrected expression for the dependence of the angular parameter y with the angle of incidence. An expression for y valid in the conventional and θ β ≅ π/2 cases has been obtained. A general expression for Bragg law and for energy resolution after a Bragg diffraction was also deduced. (author)

  11. Thermally tunable integrated planar Bragg-grating stabilized diode laser

    Science.gov (United States)

    Lynch, S. G.; Gates, J. C.; Berry, S. A.; Holmes, C.; Smith, P. G. R.

    2015-03-01

    A pair of external cavity diode lasers are fabricated using an integrated planar Bragg grating. The planar waveguide and Bragg reflector is UV-written within a glass-on-silicon chip. Intensity isolated, continuous wavelength tuning at > 1kHz modulation rate is acheived using micro-heating elements fabricated directly over the Bragg grating. Low RIN (<140dB) and low linewidth (δν ~ 200 kHz) operation is found using a heterodyne measurement. We demonstrate the lasers operating in phase-locked loop configuration where one laser is frequency-offset locked to the other.

  12. Dispersion blue-shift in an aperiodic Bragg reflection waveguide

    Science.gov (United States)

    Fesenko, Volodymyr I.; Tuz, Vladimir R.

    2016-04-01

    A particular feature of an aperiodic design of cladding of Bragg reflection waveguides to demonstrate a dispersion blue-shift is elucidated. It is made on the basis of a comparative study of dispersion characteristics of both periodic and aperiodic configurations of Bragg mirrors in the waveguide system, wherein for the aperiodic configuration three procedures for layers alternating, namely Fibonacci, Thue-Morse and Kolakoski substitutional rules are considered. It was found out that, in a Bragg reflection waveguide with any considered aperiodic cladding, dispersion curves of guided modes appear to be shifted to shorter wavelengths compared to the periodic configuration regardless of the modes polarization.

  13. Dispersion blue-shift in an aperiodic Bragg reflection waveguide

    CERN Document Server

    Fesenko, Volodymyr I

    2016-01-01

    A particular feature of an aperiodic design of cladding of Bragg reflection waveguides to demonstrate a dispersion blue-shift is elucidated. It is made on the basis of a comparative study of dispersion characteristics of both periodic and aperiodic configurations of Bragg mirrors in the waveguide system, wherein for the aperiodic configuration three procedures for layers alternating, namely Fibonacci, Thue-Morse and Kolakoski substitutional rules are considered. It was found out that, in a Bragg reflection waveguide with any considered aperiodic cladding, dispersion curves of guided modes appear to be shifted to shorter wavelengths compared to the periodic configuration regardless of the modes polarization.

  14. Resonantly enhanced Bragg-scattering spectroscopy of an atomic transition

    Science.gov (United States)

    Yang, Xudong; Qiao, Cuifang; Li, Chuanliang; Chen, Fenghua

    2016-07-01

    A novel resonantly enhanced Bragg-scattering (REBS) spectroscopy from a population difference grating (PDG) is reported. The PDG is formed by a standing-wave (SW) pump field, which periodically modulates the space population distributions of two levels in the 87Rb D1 line. Then, a probe beam, having identical frequency and orthogonal polarization with the SW pump field, is Bragg-scattered by the PDG. The research achievement shows that the Bragg-scattered light is strongest at an atomic transition, and forms an REBS spectrum with a high signal-to-noise ratio and sub-natural linewidth. The observed REBS can be applied in precise frequency measurements.

  15. The Bragg Crystal Spectrometer for AXAF

    International Nuclear Information System (INIS)

    MIT's High Resolution X-ray Spectroscopy investigation on AXAF involves two complementary dispersive instruments, a Bragg Crystal Spectrometer (BCS) and a High Energy Transmission Grating Spectrometer (HETGS). The overall goal of the investigation is to study the physical conditions in celestial sources by means of detailed measurements of their X-ray spectra. High spectral resolution measurements can be used to perform diagnostics of emitting and absorbing matter, leading to knowledge of temperature, ionization state, elemental abundance, density and optical depth. The Bragg Crystal Spectrometer gives resolving powers of 200-2000 over the energy band 0.5-8 keV and resolving powers of 50-70 over 0.14-0.5 keV. The effective collecting areas in a typical scanning observation are 4-60 cm/sup 2/, and the minimum detectable line flux is 4-30 X 10/sup -6/ photons cm/sup -2/ s/sup -1/. The BCS will be located at the AXAF focal plane. The instrument consists of 10 curved diffractors each of which has a quasi-toroidal geometry, two types of imaging proportional counters optimized for low background (one sealed and one flow), an internal monitor counter that can be inserted into the beam to measure total source flux, a mechanical system that maintains Rowland circle geometry and an appropriate command and data system. The BCS is an upgraded and improved version of the Focal Plane Crystal Spectrometer flown on the Einstein Observatory. It will be used to measure the strengths of individual lines from both point and extended objects in order to apply plasma diagnostic techniques to the study of cosmic X-ray sources

  16. Implementing circularity using partial evaluation

    DEFF Research Database (Denmark)

    Lawall, Julia Laetitia

    2001-01-01

    Complex data dependencies can often be expressed concisely by defining a variable in terms of part of its own value. Such a circular reference can be naturally expressed in a lazy functional language or in an attribute grammar. In this paper, we consider circular references in the context of an...

  17. Circular chemiresistors for microchemical sensors

    Science.gov (United States)

    Ho, Clifford K.

    2007-03-13

    A circular chemiresistor for use in microchemical sensors. A pair of electrodes is fabricated on an electrically insulating substrate. The pattern of electrodes is arranged in a circle-filling geometry, such as a concentric, dual-track spiral design, or a circular interdigitated design. A drop of a chemically sensitive polymer (i.e., chemiresistive ink) is deposited on the insulating substrate on the electrodes, which spreads out into a thin, circular disk contacting the pair of electrodes. This circularly-shaped electrode geometry maximizes the contact area between the pair of electrodes and the polymer deposit, which provides a lower and more stable baseline resistance than with linear-trace designs. The circularly-shaped electrode pattern also serves to minimize batch-to-batch variations in the baseline resistance due to non-uniform distributions of conductive particles in the chemiresistive polymer film.

  18. Risk as a social phenomenon.

    Science.gov (United States)

    Jamison, Wesley V

    2003-01-01

    What do nuclear power, smoking, and eating beef have in common? The answer is multifaceted. They all share aspects of mass production and consumption, and therefore consumer confidence comes into play in evaluating each of the products' merits. They all produce some level of anxiety--be it in response to adverse media coverage, or the successes of adversarial interest groups in publicizing those products' weaknesses--among consumers who wonder what if any level of the product should be consumed. Finally, nuclear power, smoking, and eating beef all share risk; that is, the perceived and real detriments of producing and consuming those products. Whether or not the associated risks--from increased cancer to increased heart disease--are real is beside the point. When talking about risk, scientific education must deal with the perception of risk as much as its reality. Risk is a socially defined phenomenon, and as such, the successful scientists/communicator must understand the social evaluations of it. While many scientists take a rational view of risk evaluation and consumers often make rational decisions about technological and scientific risk based upon the costs and benefits of that technology, this approach is problematic for three reasons. First, the nature of modern risks has changed in that risk is complex, incomprehensible and uncontrollable to the average person. Second, the rational approach assumes that all costs and benefits of a technology, both real and potential, both current and future, can be known and therefore rationally evaluated. This is not the case. Third, evidence from Europe indicates that trust in information sources about risk has fallen, and thus classic scientific education campaigns that rely upon increasing public knowledge and acceptance of technological and scientific risk are problematic. Because of these factors we argue that effective scientific response must begin to understand the social components of risk if campaigns to shape

  19. The phenomenon of retarded potentials

    International Nuclear Information System (INIS)

    The logic simulation of process of time delay of potential on a moved body - recipient resulted in the deduction about cyclic irregularity of time delay, that means, that the moved body makes longitudinal vibrations. A conclusion is drawn that length of longitudinal vibrations depending from three variable: the law of interaction, spacing interval between bodies of interaction and phase velocity looks like: λ=Hvph/R·F(R) (1), where λ- length of oscillations; H- factor of proportionality; vph - phase velocity of a body; R - distance between test and central bodies R(t); F(R) - law of interaction. So far as λ=vph/v, and R·F(R)=∫∞RF(R)dR=Emove, then formula (1) will be transformed into: Emove=Hvpv/λ=Hv. Thus, the energy of radiating having the similar law is only reflex of motion of a matter. The energy of oscillating motion can be expressed through linear maximal velocity. It is established, that different expressions of the same energy, result in the law of a view of a proportion for lengths of de Broglie's waves: It shows that de Broglie's waves - the actual oscillating motions of bodies, as demonstrate interference and diffraction pictures at a dissipation of the accelerated particles on crystalline gratings. This deduction has far-reaching consequences for finding - out of the cause bases of the laws of a nature. So, the quantum mechanics becomes partition of mechanics of solids and is comprises all interactions. The nuclear energy is not 'defect of mass', but is 'defect' of energy of oscillating motion: ΔE=Hv1-Hv2. Definition of real cause of nuclear energy is very important for construction of model of nuclei and for development of physics as the whole. The interconnection of the phenomenon of longitudinal vibrations of moved bodies, as result of irregularity of time delay of potential, with many other natural phenomena is looked through. By such, as: motion of planets and electrons on elliptical orbits, oscillating of dipping drips of a rain, gusts

  20. Collapse phenomenon during Chartis collateral ventilation assessment.

    Science.gov (United States)

    Gesierich, Wolfgang; Samitas, Konstantinos; Reichenberger, Frank; Behr, Juergen

    2016-06-01

    Chartis is increasingly used for bronchoscopic assessment of collateral ventilation before endobronchial valve (EBV) treatment for severe emphysema. Its prognostic value is, however, limited by the airway collapse phenomenon. The frequency and clinical significance of the collapse phenomenon remain largely unknown.We performed a retrospective analysis of 92 patients undergoing Chartis evaluation under spontaneous breathing (n=55) or jet ventilation (n=37) from May 2010 to November 2013. Collateral ventilation status (positive/negative/collapse phenomenon/unclear) was reassessed and correlated with high-resolution computed tomography (HRCT) fissure analysis and clinical response.In the absence of the collapse phenomenon, the predictive value of Chartis measurements and HRCT fissural analysis was comparable. The collapse phenomenon was observed in 31.5% of all assessments, and was more frequent in lower lobes (44.9% versus 16.9% in upper lobes) and under jet ventilation (41.4% versus 22.1% under spontaneous breathing). 69.8% of lobes with the collapse phenomenon had complete fissures. Most patients with the collapse phenomenon in the target lobe and complete fissures treated with EBVs were responders (n=11/15). All valve-treated collapse phenomenon patients with fissure defects were nonresponders (n=3).In the absence of the collapse phenomenon Chartis measurement is reliable to predict response to valve treatment. In patients with the collapse phenomenon, treatment decisions should be based on HRCT detection of fissure integrity. Chartis assessment should be performed under spontaneous breathing. PMID:27076587

  1. In Search of Multi-Peaked Reflective Spectrum with Optic Fiber Bragg Grating Sensor for Dynamic Strain Measurement

    Science.gov (United States)

    Tai, Hsiang

    2006-01-01

    In a typical optic fiber Bragg grating (FBG) strain measurement, unless in an ideal static laboratory environment, the presence of vibration or often disturbance always exists, which often creates spurious multiple peaks in the reflected spectrum, resulting in a non-unique determination of strain value. In this report we attempt to investigate the origin of this phenomenon by physical arguments and simple numerical simulation. We postulate that the fiber gratings execute small amplitude transverse vibrations changing the optical path in which the reflected light traverses slightly and non-uniformly. Ultimately, this causes the multi-peak reflected spectrum.

  2. Tunable spiral Bragg gratings in 60-nm-thick silicon-on-insulator strip waveguides.

    Science.gov (United States)

    Zou, Zhi; Zhou, Linjie; Wang, Minjuan; Wu, Kan; Chen, Jianping

    2016-06-13

    We demonstrate spiral integrated Bragg gratings (IBGs) in 60-nm-thick strip waveguides on the silicon-on-insulator (SOI) platform. The length of the spiral IBG is 2 mm, occupying an area of 147 × 141 μm2 with a minimum bending radius of 20 μm. Experiments show that the spiral IBGs exhibit a single narrow transparent peak with a Q-factor of 1 × 105 in a broad stopband, induced by the phase shift of the S-junction at the spiral center. This phenomenon is analogous to the electromagnetically induced transparency (EIT) effect. The transparent peak can periodically shift in the stopband upon heating of the S-junction using a TiN-based heater on top. The peak transmittance and Q-factor are dependent on the reflectivity of the spiral IBG. The transparent peak can be completely eliminated under a certain tuning power, and the spiral IBG hence behaves as a bandstop optical filter. The bandwidth is 0.94 nm and the extinction ratio is as high as 43 dB. The stopband can also be shifted by heating the Bragg gratings using a separate TiN heater. The experimental results agree well with the modeling results based on the transfer matrix method. PMID:27410302

  3. UV writing of advanced Bragg gratings in optical waveguides

    DEFF Research Database (Denmark)

    Jensen, Jesper Bo Damm

    2002-01-01

    The subject of this ph.d. thesis is the fabrication of Bragg gratings in optical waveguides. During the study Bragg gratings were written in both planar waveguides and optical fibers using pulsed or continuous-wave lasers operating in the ultraviolet (UV) range. The main result is the development...... half the periodicity of the index modulation profile in the Bragg grating. A phase shift in the grating is realized by shifting the UV irradiance from one polarization to the other during the grating inscription. The amplitude of the modulation can also be varied continuously by changing the ration...... phase shifts were then translated into a polarizer angle profile and the Bragg grating were written using a pulsed excimer laser. Only optical fibers were used in this part of the thesis. The high quality planar waveguides used during the study were produced in the cleanroom facility at the...

  4. Observation of sub-Bragg diffraction of waves in crystals

    CERN Document Server

    Huisman, Simon R; Hartsuiker, Alex; Woldering, Léon A; Mosk, Allard P; Vos, Willem L

    2011-01-01

    We investigate the diffraction conditions and associated formation of stopgaps for waves in crystals with different Bravais lattices. We identify a prominent stopgap in high-symmetry directions that occurs at a frequency below the ubiquitous first-order Bragg condition. This sub-Bragg diffraction condition is demonstrated by reflectance spectroscopy on two-dimensional photonic crystals with a centred rectangular lattice, revealing prominent diffraction peaks for both the sub-Bragg and first-order Bragg condition. These results have implications for wave propagation in 2 of the 5 two-dimensional Bravais lattices and 7 out of 14 three-dimensional Bravais lattices, such as centred rectangular, triangular, hexagonal and body-centred cubic.

  5. Bragg Reflection of Waves by Different Shapes of Artificial Bars

    Institute of Scientific and Technical Information of China (English)

    许泰文; 张宪国; 蔡立宏

    2002-01-01

    Experiments are performed in a wave flume to demonstrate the Bragg reflection of linear gravity waves by artificialbars. Three different artificial bars with rectangular, triangular and rectified cosinoidal shapes are placed discretely on theseabed for measurement of the Bragg reflection. A series of experimental conditions including the number of bars, the pe-riodic bar spacing, the water depth and various wave conditions are tested. Key parameters influencing the Bragg reso-nances are investigated. The experimental data are compared with the values from both theoretical and numerical models.Some key parameters have proved to be effective in describing the primary resonances. Predictive equations of the charac-teristics for the Bragg reflection are proposed in this paper.

  6. Bragg-Fresnel optics: New field of applications

    International Nuclear Information System (INIS)

    Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 108-109 photons/sec in an energy bandwidth of 10-4-10-6 and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging

  7. Structural Health Monitoring Using Fiber Bragg Grating Sensor Matrix Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fiber Bragg Grating had been identified as very important elements, especially for strain measurements in smart structures. In many applications, arrays of FBG...

  8. Bragg-Fresnel optics: New field of applications

    Energy Technology Data Exchange (ETDEWEB)

    Snigirev, A. [ESRF, Grenoble (France)

    1997-02-01

    Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 10{sup 8}-10{sup 9} photons/sec in an energy bandwidth of 10{sup -4}-10{sup -6} and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging.

  9. The localized surface plasmon resonances based on a Bragg reflector

    Science.gov (United States)

    Wang, Jie; Liu, Yumin; Yu, Zhongyuan; Ye, Chunwei; Lv, Hongbo; Shu, Changgan

    2014-09-01

    In this paper, we present the theoretical analysis on how the wavelength of the localized surface plasmon resonances of gold nanoparticle can lead shift for the resonance wavelength. In our results, we calculate the scattering cross-section, the absorption cross-section and the field enhancement due to the nanoparticle. Numerical simulation were done using the finite element method (FEM). The work that we do here is different from the previous work because we use the Bragg reflector as a substrate. The Bragg reflector has a property of high reflectivity in some certain frequency bandwidth because of its periodic structure. The coherence interference of the Bragg reflector contributes to the plasmon resonances and results in some special character for a wide variety application, from sensing to photovoltaic. The periodic number of the Bragg reflector substrate and shapes of the nanoparticles are also discussed that result in a shift of the resonance wavelength.

  10. Time/Wavelength Fiber Bragg Grating Multiplexing Sensor Array

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel time/wavelength-multiplexed fiber Bragg grating sensor array is presented. This type of sensor array has the advantages of more points for multi-point measurement, simple structure and low cost.

  11. Future Circular Colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Zimmermann, Frank

    2015-01-01

    In response to a request from the 2013 Update of the European Strategy for Particle Physics, the global Future Circular Collider (FCC) study is preparing the foundation for a next-generation large-scale accelerator infrastructure in the heart of Europe. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh), to be accommodated in a new ∼100 km tunnel near Geneva. It also includes the design of a high-luminosity electron-positron collider (FCC-ee), which could be installed in the same tunnel as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detectors, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on Nb3Sn superconductor, for the FCC-hh hadron collider, and a highly efficient superconducting radiofrequency system for the FCC-ee lepton collider. The interna...

  12. Future Circular Colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Zimmermann, Frank

    2015-01-01

    In response to a request from the 2013 Update of the European Strategy for Particle Physics, the global Future Circular Collider (FCC) study is preparing the foundation for a next-generation large-scale accelerator infrastructure in the heart of Europe. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh), to be accommodated in a new ∼100 km tunnel near Geneva. It also includes the design of a high-luminosity electron-positron collider (FCC-ee), which could be installed in the same tunnel as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detector, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on Nb3Sn superconductor, for the FCC-hh hadron collider, and a highly efficient superconducting radiofrequency system for the FCC-ee lepton collider. The internat...

  13. Towards Future Circular Colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Zimmermann, Frank

    2015-01-01

    The Large Hadron Collider (LHC) at CERN presently provides proton-proton collisions at a centre-of-mass (c.m.) energy of 13 TeV. The LHC design was started more than 30 years ago, and its physics programme will extend through the second half of the 2030’s. The global Future Circular Collider (FCC) study is now preparing for a post-LHC project. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh) in a new ∼100 km tunnel. It also includes the design of a high-luminosity electron-positron collider (FCC-ee) as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detectors, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on $Nb_3Sn$ superconductor, for the FCC-hh hadron collider, and a highly efficient superconducting radiofrequency system for the FCC-ee lepton c...

  14. Fibre Bragg Grating Components for Filtering, Switching and Lasing

    OpenAIRE

    Yu, Zhangwei

    2008-01-01

    Fibre Bragg gratings (FBGs) are key components for a vast number of applications in optical communication systems, microwave photonics systems, and optical sensors, etc. The main topic of this thesis is fibre Bragg grating fabrication and applications in direct microwave optical filtering, high speed switching and switchable dual-wavelength fibre lasers. First, a brief overview is given about the photosensitivity in optical fibre, basic FBG fabrication techniques, the popular coupled-mode the...

  15. Photonic scanning receiver using an electrically tuned fiber Bragg grating.

    Science.gov (United States)

    Rugeland, P; Yu, Z; Sterner, C; Tarasenko, O; Tengstrand, G; Margulis, W

    2009-12-15

    A 5-cm-long electrically tuned fiber Bragg grating is used to filter a microwave signal on an optical carrier at 1.55 mum. A chirped distributed-feedback structure is employed, with a transmission bandwidth of 54 MHz and relative optical carrier rejection of >30 dB for rf frequencies >2 GHz. The rapid monotonic sweep of the Bragg wavelength is translated into a fast-frequency sweep for rf analysis. PMID:20016616

  16. Particularities of the Romanian Money Laundering Phenomenon

    OpenAIRE

    Condrea Elena

    2012-01-01

    By analyzing the components of the underground economy matrix, we can say that its financial support is "money laundering" a comprehensive, dynamic phenomenon which lies in the desire of criminals to hide practiced illegal activities behind their sources of income, in order to allow a normal development in society. In this study we tried to highlight some of the features of the phenomenon of money laundering, as well as some preoccupations concerning combating this phenomenon in Romania, memb...

  17. Flow characteristics around a circular cylinder with grooves; Mizo tsuki enchu mawari no ryudo tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Oki, M. [Tokai University, Tokyo (Japan); Aoki, K. [Tokai University, Tokyo (Japan). Faculty of Engineering; Nakayama, Y.

    1998-09-25

    In the flow around a circular cylinder, the sudden decrease in the drag force occurs at around Reynolds number Re = 3 times 10{sup 5}, but the same phenomenon occurs at a lower Reynolds number in the case where there exist grooves or roughness on the circular cylinder surface. In this paper, in order to make clear the flow characteristics around a circular cylinder with grooves, the unsteady flow was analyzed by applying the RNG (Renormalization Group) {kappa}-{epsilon} turbulent model to a flow around a circular cylinder with grooves each of whose section shapes being as same as that of a dimple an a golf ball, with changing Reynolds number. This result made clear the characteristics of lift and drag, Strouhal number, flow pattern behind the circular cylinder, pressure distribution and separation points. Moreover, the time averages of these values almost agreed with the experimental values. 20 refs., 10 figs.

  18. Circularly-Polarized Microstrip Antenna

    Science.gov (United States)

    Stanton, P. H.

    1985-01-01

    Microstrip construction compact for mobile applications. Circularly polarized microstrip antenna made of concentric cylindrical layers of conductive and dielectric materials. Coaxial cable feedlines connected to horizontal and vertical subelements from inside. Vertical subelement acts as ground for horizontal subelement.

  19. Coloring fuzzy circular interval graphs

    OpenAIRE

    Eisenbrand, Friedrich; Niemeier, Martin

    2012-01-01

    Computing the weighted coloring number of graphs is a classical topic in combinatorics and graph theory. Recently these problems have again attracted a lot of attention for the class of quasi-line graphs and more specifically fuzzy circular interval graphs. The problem is NP-complete for quasi-line graphs. For the subclass of fuzzy circular interval graphs however, one can compute the weighted coloring number in polynomial time using recent results of Chudnovsky and Ovetsky and of King and Re...

  20. Energy dissipation in circular tube

    OpenAIRE

    A.D. Girgidov

    2012-01-01

    Energy dissipation distribution along the circular tube radius is important in solving such problems as calculation of heat transfer by the air flow through building envelope; calculation of pressure loss in spiral flows; calculation of cyclones with axial and tangential supply of dust-containing gas.Two types of one-dimensional radially axisymmetric flows in circular tube were considered: axial flow and rotation about the axis (Rankine vortex). Relying on two- and four-layer description of a...

  1. Writing Bragg Gratings in Multicore Fibers.

    Science.gov (United States)

    Lindley, Emma Y; Min, Seong-Sik; Leon-Saval, Sergio G; Cvetojevic, Nick; Lawrence, Jon; Ellis, Simon C; Bland-Hawthorn, Joss

    2016-01-01

    Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers. PMID:27167576

  2. Dynamic fiber Bragg grating sensing method

    Science.gov (United States)

    Ho, Siu Chun Michael; Ren, Liang; Li, Hongnan; Song, Gangbing

    2016-02-01

    The measurement of high frequency vibrations is important in many scientific and engineering problems. This paper presents a novel, cost effective method using fiber optic fiber Bragg gratings (FBGs) for the measurement of high frequency vibrations. The method uses wavelength matched FBG sensors, with the first sensor acting as a transmission filter and the second sensor acting as the sensing portion. Energy fluctuations in the reflection spectrum of the second FBG due to wavelength mismatch between the sensors are captured by a photodiode. An in-depth analysis of the optical circuit is provided to predict the behavior of the method as well as identify ways to optimize the method. Simple demonstrations of the method were performed with the FBG sensing system installed on a piezoelectric transducer and on a wind turbine blade. Vibrations were measured with sampling frequencies up to 1 MHz for demonstrative purposes. The sensing method can be multiplexed for use with multiple sensors, and with care, can be retrofitted to work with FBG sensors already installed on a structure.

  3. First order Bragg grating filters in silicon on insulator waveguides

    Science.gov (United States)

    Waugh, Peter Michael

    2008-08-01

    The subject of this project is the design; analysis, fabrication and characterisation of first order Bragg Grating optical filters in Silicon-on-Insulator (SOI) planar waveguides. It is envisaged that this work will result in the possibility of Bragg Grating filters for use in Silicon Photonics. It is the purpose of the work to create as far as is possible flat surface waveguides so as to facilitate Thermo-Optic tuning and also the incorporation into rib-waveguide Silicon Photonics. The spectral response of the shallow Bragg Gratings was modelled using Coupled Mode Theory (CMT) by way of RSoft Gratingmod TM. Also the effect of having a Bragg Grating with alternate layers of refractive index of 1.5 and 3.5 was simulated in order to verify that Silica and Silicon layered Bragg Gratings could be viable. A series of Bragg Gratings were patterned on 1.5 micron SOI at Philips in Eindhoven, Holland to investigate the variation of grating parameters with a) the period of the gratings b) the mark to space ratio of the gratings and c) the length of the region converted to Bragg Gratings (i.e. the number of grating period repetitions). One set of gratings were thermally oxidised at Philips in Eindhoven and another set were ion implanted with Oxygen ions at the Ion Beam Facility, University of Surrey, England. The gratings were tested and found to give transmission minima at approximately 1540 nanometres and both methods of creating flat surfaces were found to give similar minima. Atomic Force Microscopy was applied to the grating area of the as-implanted samples in the Advanced Technology Institute, University of Surrey, which were found to have surface undulations in the order of 60 nanometres.

  4. Flip-flop phenomenon: observations and theory

    CERN Document Server

    Elstner, D

    2005-01-01

    In many active stars the spots concentrate on two permanent active longitudes which are 180 degrees apart. In some of these stars the dominant part of the spot activity changes the longitude every few years. This so-called flip-flop phenomenon has up to now been reported in 11 stars, both single and binary alike, and including also the Sun. To explain this phenomenon, a non-axisymmetric dynamo mode, giving rise to two permanent active longitudes at opposite stellar hemispheres, is needed together with an oscillating axisymmetric magnetic field. Here we discuss the observed characteristics of the flip-flop phenomenon and present a dynamo solution to explain them.

  5. Recent advances and prospects of Bragg-Fresnel optics

    International Nuclear Information System (INIS)

    Diffraction optics, i.e. Fresnel zone plates, holograms and diffraction gratings, has a limited application in the optical wavelength range. A decrease in wavelength to 100 nm and less changes conventional relationships between different types of optical elements owing to the change in the radiation-substance interaction since absorption starts to play a more important role as compared to refraction. Therefore at 1 nm approx lt λ approx lt 100 nm focusing elements may be fabricated only from thin membranes distinguished by an abrupt change of either absorption (amplitude zone plates) or transmitted wave phase (phase zone plates). In this wavelength range it is necessary that three-dimensional Bragg and Bragg-Fresnel elements should be used. Three-dimensional elements appear to be efficient for the whole short wavelength range 10-2 nm approx lt λ approx lt 100 nm. In doing so, the use of Bragg diffraction enables fabrication of high resolution gratings, radiation modulators and prisms. Thus, two- and three-dimensional diffraction elements form the basis for production of multifunctional x-ray optics in a wide wavelength range. It is essential that these elements can be reproduced in production quantities. Below is a summary of the results obtained at the Institute of Problems of Microelectronics Technology and High Purity Materials (IPMT) of the USSR Academy of Sciences in 1984-88. Emphasis is placed on Bragg- and Bragg-Fresnel elements that are fundamental for future x-ray optics. 15 refs., 2 figs., 1 tab

  6. Circularly polarized open-loop antenna

    OpenAIRE

    Li, Rong-Lin; Fusco, Vincent F.; Nakano, Hisamatsu

    2003-01-01

    A printed circular open-loop antenna is introduced as a simple structure for producing circular polarization; the antenna is fed with a coaxial probe. By introducing a gap within the circular loop a traveling-wave current is excited and thus circularly polarized radiation can be achieved. An optimized circularly polarized antenna is designed through numerical analysis using a so-called parametric method of moment technique. Experimental verification of the new antenna is presented. The antenn...

  7. Claw-free circular-perfect graphs

    OpenAIRE

    Pecher, Arnaud; Zhu, Xuding

    2007-01-01

    The circular chromatic number of a graph is a well studied refinement of the chromatic number. Circular perfect graphs is a superclass of perfect graphs defined by means of this more general coloring concept. This paper studies claw free circular perfect graphs. A consequence of the strong perfect graph theorem is that minimal circular perfect graphs G. In contrast to this result, it is shown in that minimal circular imperfect graphs G can have arbitrarily large independence number and arbitr...

  8. Acoustojet: acoustic analogue of photonic jet phenomenon

    CERN Document Server

    Minin, Igor V

    2016-01-01

    It has been demonstrated for the first time that an existence of acoustic analogue of photonic jet phenomenon, called acoustojet, providing for subwavelength localization of acoustic field in the shadow area of arbitrary 3D penetrable mesoscale particle, is possible.

  9. Professor Nambu, String Theory and Moonshine Phenomenon

    CERN Document Server

    Eguchi, Tohru

    2016-01-01

    I first recall the last occasion of meeting the late Professor Yoichiro Nambu in a hospital in Osaka. I then present a brief introduction to the moonshine phenomenon in string theory which is under recent investigations.

  10. Tamm-Horsfall phenomenon in neonates

    International Nuclear Information System (INIS)

    Tamm-Horsfall phenomenon is a transient hyperechogenicity of the renal pyramids during the first few days of life. The purpose of this study was to determine whether there is a correlation between the Tamm-Horsfall phenomenon and the pathology of pregnancy, the kind of delivery, or selected biochemical parameters of urine. The study involved 153 neonates, divided into two groups based on pregnancy age. Group I consisted of 118 full term neonates born in the 37th - 42nd week of pregnancy, while Group II included 35 premature neonates born before the 37th week of pregnancy. Ultrasonograms of the kidneys were performed on the 1st and 3rd day of life, as well as examinations of urine protein, creatinine, uric acid and urea concentration. The Examinations were repeated in the 2nd month of life after making a diagnosis of Tamm-Hosfall phenomenon. Tamm-Horsfall phenomenon was diagnosed in 32 eutrophic children (22.7% of the group). Among the term neonates, diagnoses of Tamm-Horsfall phenomenon were made in 24.6% of the children (29/118), as opposed to 8.6% (3/35) in the preterm group in. Pregnancy was terminated by caesarean section in 22 cases (68.7 % of all 32). 10 children (31.3 % of all 32) were born spontaneously (p=0.01). Significantly higher urine protein and creatinine concentrations were noted in this group only on the 3rd day of life. Children with Tamm-Horsfall phenomenon had greater body mass at birth (p=0.01) than the others. Repeated examinations of 23 children diagnosed with Tamm-Horsfall phenomenon performed in the 2nd month of life showed that this phenomenon had disappeared. Tamm-Horsfall phenomenon is observed more often in children delivered by caesarean section. Children diagnosed with Tamm-Horsfall phenomenon have higher urine levels of protein and creatinine on the 3rd day of life. Tamm-Horsfall phenomenon is observed more often in term, eutrophic children. (author)

  11. Spatially discontinuous ionization phenomenon in inhomogeneous soil

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    By using X-ray film imaging technology,a phenomenon of discontinuous ionization was observed in the inhomogeneous soil around the grounding electrode on which a surge voltage was applied.A simplified two-phase solid-gas model was built to study the electric field distribution in the soil to explain the discontinuous ionization phenomenon.Analysis showed the differences of the dielectric properties,the shapes and sizes of soil particles can cause discontinuous ionization in the soil.

  12. PROSTITUTION PHENOMENON - LEGAL AND SOCIAL ASPECTS

    OpenAIRE

    Ilinca Alexandra TÃLNAR; Camelia Augusta HIMCINSCHI

    2012-01-01

    The prostitution phenomenon is a global, complex, controversial, and problematic phenomenon which remains one of the current subjects debated at national and international level. From a judicial point of view, despite of the numerous legal measures and sporadic actions realized by the police, prostitution continues to be present in Romania, partially due to the low efficiency of legal controls and laws’ implementation. In this respect, we have focused on the distinction between offence and co...

  13. Open source innovation phenomenon, participant behaviour, impact

    CERN Document Server

    Herstatt, Cornelius

    2015-01-01

    Open Source Innovation (OSI) has gained considerable momentum within the last years. Academic and management practice interest grows as more and more end-users consider and even participate in Open Source product development like Linux, Android, or Wikipedia. Open Source Innovation: Phenomenon, Participant Behaviour, Impact brings together rigorous academic research and business importance in scrutinizing OCI from three perspectives: The Phenomenon, Participants' Behavior, and Business Implications. The first section introduces OCI artefacts, including who is participating and why, and provide

  14. Koebner phenomenon of the ear canal skin.

    LENUS (Irish Health Repository)

    Young, O

    2009-02-01

    The Koebner phenomenon originally described the appearance of psoriatic lesions in the uninvolved skin of patients with psoriasis as a consequence of trauma. We describe a case of concurrent lichen planus and sarcoidosis in the auditory canal, which represents an unusual manifestation of the Koebner phenomenon. This is the first case of concurrent lichen planus and sarcoidosis in the head and neck region and highlights the need for biopsy to allow accurate histopathological diagnosis and treatment.

  15. Koebner phenomenon of the ear canal skin.

    LENUS (Irish Health Repository)

    Young, O

    2012-02-01

    The Koebner phenomenon originally described the appearance of psoriatic lesions in the uninvolved skin of patients with psoriasis as a consequence of trauma. We describe a case of concurrent lichen planus and sarcoidosis in the auditory canal, which represents an unusual manifestation of the Koebner phenomenon. This is the first case of concurrent lichen planus and sarcoidosis in the head and neck region and highlights the need for biopsy to allow accurate histopathological diagnosis and treatment.

  16. Validation of the Impostor Phenomenon Among Managers

    OpenAIRE

    Sonja eRohrmann; Myriam eBechtoldt; Mona eLeonhardt

    2016-01-01

    Following up on earlier investigations, the present research aims to validate the construct impostor phenomenon by taking personality correlates into account and to examine whether the impostor phenomenon is a construct in its own right. In addition, gender effects as well as effects on working style and stress or strain are examined. In an online study we surveyed a sample of N = 242 individuals occupying leadership positions in different sectors. Confirmatory factor analyses provide empiric...

  17. Validation of the Impostor Phenomenon among Managers

    OpenAIRE

    Rohrmann, Sonja; Bechtoldt, Myriam N.; Leonhardt, Mona

    2016-01-01

    Following up on earlier investigations, the present research aims at validating the construct impostor phenomenon by taking other personality correlates into account and to examine whether the impostor phenomenon is a construct in its own right. In addition, gender effects as well as associations with dispositional working styles and strain are examined. In an online study we surveyed a sample of N = 242 individuals occupying leadership positions in different sectors. Confirmatory factor anal...

  18. Orgasm Induced Seizures: A Rare Phenomenon.

    Science.gov (United States)

    Chaukimath, S P; Patil, P S

    2015-01-01

    A variety of stimuli can cause reflex seizures, Some triggers include light, music and cognitive phenomenon. There are case reports however where the phenomenon of sexual activity has been a trigger for epileptic seizures. Most of these cases reported are in women so far, and were found to be localized to right cerebral hemisphere. We report a case of a 36-year-old male with orgasm-induced seizures, with other atypical features compared to majority of previous reports. PMID:27057393

  19. Prussian phenomenon and its historical distortion

    OpenAIRE

    Oleg Y. Plenkov; Vladimir N. Baryshnikov; Viktor N. Borisenko; Vladimir L. Piankewich; Nina E. Adamova

    2016-01-01

    The article deals with the phenomenon of Prussia. Once, Prussia had been the largest continental Protestant state in Europe. The main issue of this phenomenon is that upon the tragic events of the World War II Prussian history and heritage had been considerably distorted, in order to compensate somehow for the dreadful casualties suffered by the victorious powers. The common European misconception implied that Prussia had been the bulwark of militarism, and therefore had to bear all the respo...

  20. Temperature Compensation for Double Fiber Bragg Grating Sensors

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-cheng; LIU Jia; ZHENG Jian-bang

    2006-01-01

    A novel double fiber Bragg grating(FBG) strain sensor configuration is presented. Temperature compensation method is based on double FBG moored on a rhombus frame. Through the theoretical analysis,the relation between relative shift of Bragg wavelength and the strain applied on the sensor is obtained,and the analytical expression of strain sensitivity coefficient is also given. The experiment results show that:in the strain range of 0~0.8 mm,the relation between the relative shift of Bragg wavelength and applied strain is linear,and the dispersion of double FBG wavelength at the range of -25 ℃~60 ℃ is 0~0.002 nm. The strain sensitivity of the displacement sensor configuration is 0.171 nm/με,and is nearly twice than that of single FC sensor.

  1. Performance of a Bragg curve detector for heavy ion identification

    International Nuclear Information System (INIS)

    By using Bragg curve spectroscopy, one can measure atomic number and energy of high energy heavy ions stopping in a gas-filled ionization chamber with longitudinal electric field. In this paper, we report on the results obtained with an isobutane filled detector. An energy resolution of 0.8% fwhm and a Z resolution of 2.7% fwhm were achieved for elastically scattered 300 MeV 40Ar ions. We study the Bragg peak amplitude dependence on the energy of the incoming ions, a dependence presumably due to the Frisch grid screening inefficiency. The corrected Bragg peak spectrum of inelastically scattered 300 MeV 40Ar ions exhibits a satisfactory Z separation around Z = 18. (orig.)

  2. Performance of a Bragg curve detector for heavy ion identification

    Science.gov (United States)

    Asselineau, J. M.; Duchon, J.; L'Haridon, M.; Mosrin, P.; Regimbart, R.; Tamain, B.

    1982-12-01

    By using Bragg curve spectroscopy, one can measure atomic number and energy of high energy heavy ions stopping in a gas-filled ionization chamber with longitudinal electric field. In this paper, we report on the results obtained with an isobutane filled detector. An energy resolution of 0.8% fwhm and a Z resolution of 2.7% fwhm were achieved for elastically scattered 300 MeV 40Ar ions. We study the Bragg peak amplitude dependence on the energy of the incoming ions, a dependence presumably due to the Frisch grid screening inefficiency. The corrected Bragg peak spectrum of inelastically scattered 300 MeV 40Ar ions exhibits a satisfactory Z separation around Z=18.

  3. Flexible nanofiber-coupled hybrid plasmonic Bragg grating.

    Science.gov (United States)

    Liu, Sheng; Zhou, Linjie; Xu, Jian; Wang, Xinyi; Chen, Jianping

    2016-05-01

    We report a hybrid plasmonic Bragg grating composed of a nanofiber coupled with orthogonally oriented metal strips. Numerical simulations are performed to study the transmission and reflection spectra of the grating. It shows that the TM polarization has much stronger Bragg reflection due to the excitation of hybrid plasmonic modes. The dependence of reflection peaks on several key device parameters is analyzed. Light propagation simulation further reveals that both fundamental and first-order TM modes are excited upon Bragg reflection, leading to two separate peaks in the spectrum. We implement the prototype device by attaching a nanofiber onto the surface of an array of sub-micrometer-wide metal strips. The main reflection peak is measured to have a 3-dB bandwidth of 15 nm and out-of-band rejection of more than 30 dB. The effects of nanofiber radius, alignment angle and coupling length on the device performance are also experimentally investigated. PMID:27137547

  4. Tunable plasmonic Bragg reflector with different graphene nanoribbon widths

    Science.gov (United States)

    Zhuang, Huawei; Kong, Fanmin; Li, Kang; Sheng, Shiwei

    2015-09-01

    We propose and numerically analyze a Bragg reflector composed of periodically arranged graphene nanoribbon waveguides with different widths. Because of the unique property of the graphene edge mode, the effective index contrast used for the reflector can be obtained by designing graphene nanoribbons with different widths without changing the dielectric substrate structure. Good band stop filtering characteristics are shown at the band gap of the transmission spectrum by numerical simulation. The performance of the proposed Bragg reflector is analyzed in terms of different parameters, such as the chemical potential, the number of periods, and the size of the unit cell. The proposed Bragg reflector will be expected to have important potential applications in the highly integrated SPP-based photonic devices.

  5. A plating method for metal coating of fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    Yulong Li; Hua Zhang; Yan Feng; Gang Peng

    2009-01-01

    We present a method for metal coating optical fiber and in-fiber Bragg grating. The technology process which is based on electroless plating and electroplating method is described in detail. The fiber is firstly coated with a thin copper or nickel plate with electroless plating method. Then, a thicker nickel plate is coated on the surface of the conductive layer. Under the optimum conditions, the surfaces of chemical plating and electroplating coatings are all smooth and compact. There is no visible defect found in the cross-section. Using this two-step metallization method, the in-fiber Bragg grating can be well protected and its thermal sensitivity can be enhanced. After the metallization process, the fiber sensor is successfully embedded in the 42CrMo steel by brazing method. Thus a smart metal structure is achieved. The embedding results show that the plating method for metallization protection of in-fiber Bragg grating is effective.

  6. Holographic Bragg gratings: measurements and examination diffraction parameters

    CERN Document Server

    Tikhonov, E A

    2015-01-01

    Measurement and analysis of diffraction parameters of thick transmission holographic phase gratings recorded on PHC-488 photopolymer are presented. Precision determination of the spatial grating period is executed by Bragg angle measurement for two precisely known wavelengths in the first diffraction order and also by Bragg angle measurement on one wavelength in the first and second diffraction orders. Determination of actual grating thickness and depths of spatial modulation of a holographic recording, which are responsible for their main optical characteristics, is carried out with the application of H. Kogelnik 2-wave coupled model. Calculated and experimental Bragg angles in two orthogonal orientated planes of linear polarized laser light were used to confirm theoretical model with experimental results. Extreme values of the diffraction parameters, efficiency and spectral resolution, important for holographic phase grating applications are analyzed.

  7. Validation of the Impostor Phenomenon among Managers.

    Science.gov (United States)

    Rohrmann, Sonja; Bechtoldt, Myriam N; Leonhardt, Mona

    2016-01-01

    Following up on earlier investigations, the present research aims at validating the construct impostor phenomenon by taking other personality correlates into account and to examine whether the impostor phenomenon is a construct in its own right. In addition, gender effects as well as associations with dispositional working styles and strain are examined. In an online study we surveyed a sample of N = 242 individuals occupying leadership positions in different sectors. Confirmatory factor analyses provide empirical evidence for the discriminant validity of the impostor phenomenon. In accord with earlier studies we show that the impostor phenomenon is accompanied by higher levels of anxiety, dysphoric moods, emotional instability, a generally negative self-evaluation, and perfectionism. The study does not reveal any gender differences concerning the impostor phenomenon. With respect to working styles, persons with an impostor self-concept tend to show perfectionist as well as procrastinating behaviors. Moreover, they report being more stressed and strained by their work. In sum, the findings show that the impostor phenomenon constitutes a dysfunctional personality style. Practical implications are discussed. PMID:27313554

  8. Validation of the Impostor Phenomenon among Managers

    Science.gov (United States)

    Rohrmann, Sonja; Bechtoldt, Myriam N.; Leonhardt, Mona

    2016-01-01

    Following up on earlier investigations, the present research aims at validating the construct impostor phenomenon by taking other personality correlates into account and to examine whether the impostor phenomenon is a construct in its own right. In addition, gender effects as well as associations with dispositional working styles and strain are examined. In an online study we surveyed a sample of N = 242 individuals occupying leadership positions in different sectors. Confirmatory factor analyses provide empirical evidence for the discriminant validity of the impostor phenomenon. In accord with earlier studies we show that the impostor phenomenon is accompanied by higher levels of anxiety, dysphoric moods, emotional instability, a generally negative self-evaluation, and perfectionism. The study does not reveal any gender differences concerning the impostor phenomenon. With respect to working styles, persons with an impostor self-concept tend to show perfectionist as well as procrastinating behaviors. Moreover, they report being more stressed and strained by their work. In sum, the findings show that the impostor phenomenon constitutes a dysfunctional personality style. Practical implications are discussed. PMID:27313554

  9. BRAGG-PEAK LOCATION EMPLOYING A MAXIMUM-ENTROPY FORMALISM

    OpenAIRE

    Lehmann, M.; Robinson, T.; Wilkins, S.

    1986-01-01

    The maximum entropy method has been tried on simulated data from a small 2-dimensional position-sensitive detector. Constraints were introduced to account for smoothness and the fact that only one peak was found within the frame of the recording. Analysis of a large number of weak Bragg peaks with I/σ(I) < 9 and of different size and background showed the method to give virtually bias-free results. The computing time is sufficiently low to allow real time use on measurements of a single Bragg...

  10. Temperature sensor based on dual fiber Bragg gratings

    OpenAIRE

    Ekestam, Henrik; Larsson, Jim

    2015-01-01

    The objective of the project was to examine if it was possible to develop a low-cost temperature sensor using dual fiber Bragg gratings (FBGs). The intention was to use one FBG as a reference and let the other FBG function as the sensor. The study shows that it is possible to characterize the temperature sensitivity of each FBG and use the reference to sweep over the applicable spectrum to find the Bragg-wavelength of the sensor. This could be done measuring only the total intensity instead o...

  11. A novel optical filter of fiber Bragg grating

    Institute of Scientific and Technical Information of China (English)

    LI; Xiaolu; JIANG; Yuesong

    2006-01-01

    A theory of a novel optical filter of drawing the fiber Bragg grating by the heated elastic sheet is advanced. Based on the heat conduction equation, a set of functions of temperature and thermal expansion on the heated elastic sheet are calculated. And the most displacement of the heated elastic sheet is also described. Finally the expression of the reflected Bragg wavelength deviation in terms of the thermal power density of heat-source is deduced. The physics feasibility of these conclusions mentioned above is proved. It is a potential value for the novel optical filter to research.

  12. Bridge pier scour measurement by means of Bragg grating arrays

    Directory of Open Access Journals (Sweden)

    Manzoni S.

    2010-06-01

    Full Text Available This paper deals with a new method to measure scour level at bridge piers. The proposed technique is based on an array of Bragg grating temperature sensors, heated by an electrical circuit. The Bragg gratings in water sense a lower temperature than those buried in the river bed, because of the different heat scattering principles in the two situations. Furthermore the response of each sensor is slower if it is buried in the bed, with respect to the case it is in water. The paper presents laboratory tests, showing the method effectiveness and reliability, and it explains the advantages with respect to other more traditional methodologies to measure scour level.

  13. Bragg grating chemical sensor with hydrogel as sensitive element

    Institute of Scientific and Technical Information of China (English)

    Xiaomei Liu(刘小梅); Shilie Zheng(郑史烈); Xianmin Zhang(章献民); Jun Cong(丛军); Kangsheng Chen(陈抗生); Jian Xu(徐坚)

    2004-01-01

    A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.

  14. Podokinetic circular vection: characteristics and interaction with optokinetic circular vection.

    Science.gov (United States)

    Becker, W; Kliegl, K; Kassubek, J; Jürgens, R

    2016-07-01

    Stabilising horizontal body orientation in space without sight on a rotating platform by holding to a stationary structure and circular 'treadmill' stepping in the opposite direction can elicit an illusion of self-turning in space (Bles and Kapteyn in Agressologie 18:325-328, 1977). Because this illusion is analogous to the well-known illusion of optokinetic circular vection (oCV), we call it 'podokinetic circular vection' (pCV) here. Previous studies using eccentric stepping on a path tangential to the rotation found that pCV was always contraversive relative to platform rotation. In contrast, when our subjects stepped at the centre of rotation about their vertical axis, we observed an inverted, ipsiversive pCV as a reproducible trait in many of our subjects. This ipCV occurred at the same latency as the pCV of subjects reporting the actually expected contraversive direction, but had lower gain. In contrast to pCV, the nystagmus accompanying circular treadmill stepping had the same direction in all individuals (slow phase in the direction of platform motion). The direction of an individual's pCV predicted the characteristics of the CV resulting from combined opto- and podokinetic stimulation (circular treadmill stepping while viewing a pattern rotating together with the platform): in individuals with contraversive pCV, latency shortened and both gain and felt naturalness increased in comparison with pure oCV, whereas the opposite (longer latency, reduced gain and naturalness) occurred in individuals with ipCV. Taken together, the reproducibility of ipCV, the constant direction of nystagmus and the fact that pCV direction predicts the outcome of combined stimulation suggest that ipCV is an individual trait of many subjects during compensatory stepping at the centre of rotation. A hypothetical model is presented of how ipCV possibly could arise. PMID:26965438

  15. Measurement of distributed strain and temperature based on higher order and higher mode Bragg conditions

    Science.gov (United States)

    Sirkis, James S. (Inventor); Sivanesan, Ponniah (Inventor); Venkat, Venki S. (Inventor)

    2001-01-01

    A Bragg grating sensor for measuring distributed strain and temperature at the same time comprises an optical fiber having a single mode operating wavelength region and below a cutoff wavelength of the fiber having a multimode operating wavelength region. A saturated, higher order Bragg grating having first and second order Bragg conditions is fabricated in the optical fiber. The first order of Bragg resonance wavelength of the Bragg grating is within the single mode operating wavelength region of the optical fiber and the second order of Bragg resonance wavelength is below the cutoff wavelength of the fiber within the multimode operating wavelength region. The reflectivities of the saturated Bragg grating at the first and second order Bragg conditions are less than two orders of magnitude of one another. In use, the first and second order Bragg conditions are simultaneously created in the sensor at the respective wavelengths and a signal from the sensor is demodulated with respect to each of the wavelengths corresponding to the first and second order Bragg conditions. Two Bragg conditions have different responsivities to strain and temperature, thus allowing two equations for axial strain and temperature to be found in terms of the measure shifts in the primary and second order Bragg wavelengths. This system of equations can be solved for strain and temperature.

  16. Distributed Feedback in and Distributed Bragg Reflection from Periodic Chiral Structures.

    Science.gov (United States)

    Flood, Kevin Michael

    1995-01-01

    In this study, we examine the combined effects of electromagnetic chirality and periodicity on wave interactions in active and passive media. Isotropic chiral media have the unique property of possessing two intrinsic indices of refraction without the additional complication of anisotropy. The two refractive indices arise from different propagation velocities for right-circularly-polarized (RCP) and left -circularly-polarized (LCP) waves (i.e., circular birefringence), and their existence suggests that chiral media may be used in conjunction with the coherent feedback characteristics of periodic structures to create structures that favor either RCP or LCP solutions. In this study, we develop the theory that describes the wave interactions in such periodic chiral structures, and we examine several representative cases, including active devices, to identify specific characteristics. Bandgap characteristics are developed here for finite-length slabs of periodic chiral media using coupled -mode theory. The theory shows that stratified, periodic, isotropic media fall into one of three categories: subchiral, chiral, or superchiral. The superchiral periodic medium possesses three stop bands for the fundamental Bragg condition where the three stop bands are associated with LCP rightarrow RCP coupling, LCP to LCP coupling, and RCP to RCP coupling. We examine the reflectivity for superchiral periodic media to show the degree of polarization mode isolation for both passive and active structures. We also study the relationships among the chiral constitutive parameters (i.e., permittivity, permeability, and chirality admittance) based on a canonical chiral media model, and we address how the presence of chirality may enhance the reflectivity from periodic slabs. In addition to periodic media, we investigate the role of chirality for mode coupling in symmetric planar waveguides with periodic boundaries. Such structures are of current interest as mode converters, filters, and

  17. Magnetic hysteresis of an artificial square ice studied by in-plane Bragg x-ray resonant magnetic scattering

    Directory of Open Access Journals (Sweden)

    J. P. Morgan

    2012-06-01

    Full Text Available We report X-ray resonant magnetic scattering studies of a Permalloy artificial square ice nanomagnet array, focussing on the field-driven evolution of the sum Σ and difference Δ signals of left and right handed circularly polarized synchrotron X-rays at different lateral positions in reciprocal space Qx. We used X-rays tuned to the Fe L3 resonance energy, with the scattering plane aligned along a principal symmetry axis of the array. Details of the specular Δ hysteresis curve are discussed, following the system magnetization from an initial demagnetized state. The periodic structure gives rise to distinct peaks at in-plane reciprocal Bragg positions, as shown by fitting Σ(Qx to a model based on a simple unit cell structure. Diffraction order-dependent hysteresis in Δ is observed, indicative of the reordering of magnetization on the system's two interpenetrating sublattices, which markedly deviates from an ideal Ising picture under strong applied fields.

  18. Circular RNA expands its territory.

    Science.gov (United States)

    Bao, Chunyang; Lyu, Dongbin; Huang, Shenglin

    2016-03-01

    Circular RNAs (circRNAs) represent a novel class of widespread non-coding RNAs in eukaryotes. They are unusually stable RNA molecules with cell type-specific expression patterns, and are predominantly present in the cytoplasm. We recently demonstrated the existence of abundant circRNAs in exosomes and suggest a potential application of exosomal circRNAs for cancer detection. PMID:27308606

  19. High intensity circular proton accelerators

    International Nuclear Information System (INIS)

    Circular machines suitable for the acceleration of high intensity proton beams include cyclotrons, FFAG accelerators, and strong-focusing synchrotrons. This paper discusses considerations affecting the design of such machines for high intensity, especially space charge effects and the role of beam brightness in multistage accelerators. Current plans for building a new generation of high intensity 'kaon factories' are reviewed. 47 refs

  20. Application of circular filter inserts

    International Nuclear Information System (INIS)

    High efficiency particulate air (HEPA) filters are used in the ventilation of nuclear plant as passive clean-up devices. Traditionally, the work-horse of the industry has been the rectangular HEPA filter. An assessment of the problems associated with remote handling, changing, and disposal of these rectangular filters suggested that significant advantages to filtration systems could be obtained by the adoption of HEPA filters with circular geometry for both new and existing ventilation plants. This paper covers the development of circular geometry filters and highlights the advantages of this design over their rectangular counterparts. The work has resulted in a range of commercially available filters for flows from 45 m3/h up to 3400 m3/h. This paper also covers the development of a range of sizes and types of housings that employ simple change techniques which take advantage of the circular geometry. The systems considered here have been designed in response to the requirements for shielded (remote filter change) and for unshielded facilities (potentially for bag changing of filters). Additionally the designs have allowed for the possibility of retrofitting circular geometry HEPA filters in place of the rectangular geometry filter

  1. Historical Aspects in Tolerance Phenomenon Research

    Directory of Open Access Journals (Sweden)

    Janat A. Karmanova

    2013-01-01

    Full Text Available The article examines the historical aspect of the tolerance phenomenon research, particularly the study of tolerance in the age of Antiquity, Middle Ages, New Times, Enlightenment. It is remarkable that the problem of tolerance, emerged in Western civilization on religious grounds, laid the foundation for all other freedoms, attained in many countries. Besides, the article attaches special attention to the researchers of the East, such as Abu Nasr al-Farabi, Khoja Ahmed Yasawi, studies the historical aspect of works by Kazakhstan thinkers A. Kunanbayev, C. Valikhanova, K.B. Zharikbayev, S.K. Kaliyev, A.N. Nysanbayev, A.I. Artemev and others. The analysis of historical research of the tolerance phenomenon brings the author to the conclusion that religious freedom was the starting point for the emergence of new areas of tolerance display. The content of this phenomenon changed according to the historical peculiarities of the societies’ development

  2. Circular orbits and related quasiharmonic oscillatory motion of charged particles around weakly magnetized rotating black holes

    Science.gov (United States)

    Tursunov, Arman; Stuchlík, Zdeněk; Kološ, Martin

    2016-04-01

    We study the motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasicircular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyze the circular orbits using the so-called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum, and specific energy of the circular orbits in dependence on the black-hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with an outward-oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged particles in the radial and vertical directions related to the equatorial circular orbits and study the radial profiles of the radial, ωr; vertical, ωθ; and orbital, ωϕ, frequencies, finding significant differences in comparison to the epicyclic geodesic circular motion. The most important new phenomenon is the existence of toroidal charged particle epicyclic motion with ωr˜ωθ≫ωϕ that could occur around retrograde circular orbits with an outward-oriented Lorentz force. We demonstrate that for the rapidly rotating black holes the role of the "Wald induced charge" can be relevant.

  3. Rational solitons in deep nonlinear optical Bragg grating

    NARCIS (Netherlands)

    Alatas, H.; Iskandar, A.A.; Tjia, M.O.; Valkering, T.P.

    2006-01-01

    We have examined the rational solitons in the Generalized Coupled Mode model for a deep nonlinear Bragg grating. These solitons are the degenerate forms of the ordinary solitons and appear at the transition lines in the parameter plane. A simple formulation is presented for the investigation of the

  4. The Wavelength Shifting and Temperature Athermalization of Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Yu; e; Kong

    2003-01-01

    The wavelength shifting properties and the temperature athermalization technology of fiber Bragg grating (FBG) were studied in this paper, and then two different athermalization methods were introduced. The research shows that FBG with athermalization by applying the substrate with negative coefficient of thermal expansion is effective and can be used in many fields.

  5. A Bragg curve ionization chamber for acceleration mass spectrometry

    International Nuclear Information System (INIS)

    An ionization chamber based on the Bragg curve spectrometry method to be used as the final detector in a accelerator mass spectrometry system is described. The first tests with a Cl beam give energy resolution of 1% and Z resolving power of 72 at Z=17

  6. Ultrafast Laser Fabrication of Bragg Waveguides in GLS Chalcogenide Glass

    Directory of Open Access Journals (Sweden)

    McMillen Ben

    2013-11-01

    Full Text Available We present work on the fabrication of Bragg waveguides in gallium-lanthanum-sulfide chalcogenide glass using an ultrafast laser. Waveguides were written with a single pass while modulating the writing beam. The spatial and temporal profile of the writing beam was ontrolled during waveguide fabrication in order to control the shape and size of the waveguide cross-section.

  7. Crystal clear the autobiographies of Sir Lawrence and Lady Bragg

    CERN Document Server

    Thomson, Patience

    2015-01-01

    The main body of this book contains the hitherto unpublished autobiographies of both William Lawrence Bragg, an innovative scientist who won the Nobel Prize for Physics in 1915, and his wife, Alice, a Mayor of Cambridge and National Chairman of Marriage Guidance. Their autobiographies give unusual insights into the lives and times of two distinguished people and the real personalities behind their public appearance.

  8. Linearized Bragg grating assisted electro-optic modulator.

    Science.gov (United States)

    Khurgin, Jacob B; Morton, Paul A

    2014-12-15

    We propose a new linearized electro-optic modulator in which linearization is achieved by modulating the index of a Bragg grating reflector placed in the arm(s) of a Michelson Interferometer. This grating-assisted Michelson (GAMI) modulator can operate as either an intensity or amplitude modulator, and is shown to significantly improve the linearity of microwave photonics links. PMID:25503037

  9. Growth and characterization of nitride-based distributed Bragg reflectors

    Energy Technology Data Exchange (ETDEWEB)

    Kruse, Carsten; Dartsch, Heiko; Aschenbrenner, Timo; Figge, Stephan; Hommel, Detlef [Section Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen (Germany)

    2011-08-15

    We report on a systematic study concerning the realization of nitride-based distributed Bragg reflectors (DBRs) for opto-electronic applications in the near-UV to visible spectral range. Different material combinations are used in order to find an optimized trade-off concerning peak reflectivity, stop band width, and strain state of the Bragg mirrors. For the high refractive index material GaN is used in all cases, while for the low index material a layer of either AlGaN or AlInN, respectively, or a AlN/(In)GaN short-period superlattice (SL) is employed. The best peak reflectivity of 97% at a wavelength of 495 nm is achieved for a lattice matched Bragg reflector based on the GaN/AlInN material combination. Transmission electron microscopy image of a 30-fold distributed Bragg reflector consisting of AlInN (dark) and GaN (bright) layers. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Dynamic gate algorithm for multimode fiber Bragg grating sensor systems

    DEFF Research Database (Denmark)

    Ganziy, Denis; Jespersen, O.; Woyessa, Getinet;

    2015-01-01

    -to-noise ratio and different peak shapes. Our simulations and experiments demonstrate that the DGA method is fast and robust with better stability and accuracy than conventional algorithms. This makes it very attractive for future implementation in sensing systems, especially based on multimode fiber Bragg...

  11. Laser sensor with Bragg gratings of fiber optics to physics parameter measuring

    International Nuclear Information System (INIS)

    We present the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980nm, an 4.23 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength increases their temperature which can be used as a sensor element. The laser generation thus shows that the Bragg grating is increasing their temperature. We used a Peltier cell for to change gradually the temperature. (Author)

  12. Non-genetic phenomenons of radiosensitivity

    International Nuclear Information System (INIS)

    Transcription factors are activated by radiation induced DNA damage. This is followed by cell cycle regulation (cell cycle blocks and DNA repair), which influence radiosensitivity. This phenomenon is seen as a genetic effect. Proteins as transcription factors (e.g. NF-κB) are directly activated by ionizing radiation, genes coding for cytokines and growth factors are expressed and influence the radiosensitivity. Damage of the cell membrane also induces signal transduction cascades and activates genes via transcription factors, which influence radiosensitivity. The latter two phenomenons are described as non genetics and will get more and more importance in He radiobiology. (orig.)

  13. Flip-flop phenomenon: observations and theory

    OpenAIRE

    Elstner, D.; Korhonen, H.

    2005-01-01

    In many active stars the spots concentrate on two permanent active longitudes which are 180 degrees apart. In some of these stars the dominant part of the spot activity changes the longitude every few years. This so-called flip-flop phenomenon has up to now been reported in 11 stars, both single and binary alike, and including also the Sun. To explain this phenomenon, a non-axisymmetric dynamo mode, giving rise to two permanent active longitudes at opposite stellar hemispheres, is needed toge...

  14. Spectrometer with CMOS demodulation of fiber optic Bragg grating sensors

    Science.gov (United States)

    Christiansen, Martin Brokner

    A CMOS imager based spectrometer is developed to interrogate a network containing a large number of Bragg grating sensors. The spectrometer uses a Prism-Grating- Prism (PGP) to spectrally separate serially multiplexed Bragg reflections on a single fiber. As a result, each Bragg grating produces a discrete spot on the CMOS imager that shifts horizontally as the Bragg grating experiences changes in strain or temperature. The reflected wavelength of the spot can be determined by finding the center of the spot produced. The use of a randomly addressable CMOS imager enables a flexible sampling rate. Some fibers can be interrogated at a high sampling rate while others can be interrogated at a low sampling rate. However, the use of a CMOS imager leads to several unique problems in terms of signal processing. These include a logarithmic pixel response, a low signal-to-noise ratio, a long pixel time constant, and software issues. The expected capabilities of the CMOS imager based spectrometer are determined with a theoretical model. The theoretical model tests three algorithms for determining the center of the spot: single row centroid, single row parabolic fit, and entire spot centroid. The theoretical results are compared to laboratory test data and field test data. The CMOS based spectrometer is capable of interrogating many optical fibers, and in the configuration tested, the fiber bundle consisted of 23 fibers. Using this system, a single fiber can be interrogated from 778 nm to 852 nm at 2100 Hz or multiple fibers can be interrogated over the same wavelength so that the total number of fiber interrogations is up to 2100 per second. The reflected Bragg wavelength can be determined within +/-3pm, corresponding to a +/-3μɛ uncertainty.

  15. Nonlinear light propagation in cholesteric liquid crystals with a helical Bragg microstructure

    International Nuclear Information System (INIS)

    Nonlinear optical propagation in cholesteric liquid crystals (CLC) with a spatially periodic helical molecular structure is studied experimentally and modeled numerically. This periodic structure can be seen as a Bragg grating with a propagation stopband for circularly polarized light. The CLC nonlinearity can be strengthened by adding absorption dye, thus reducing the nonlinear intensity threshold and the necessary propagation length. As the input power increases, a blue shift of the stopband is induced by the self-defocusing nonlinearity, leading to a substantial enhancement of the transmission and spreading of the beam. With further increase of the input power, the self-defocusing nonlinearity saturates, and the beam propagates as in the linear-diffraction regime. A system of nonlinear couple-mode equations is used to describe the propagation of the beam. Numerical results agree well with the experiment findings, suggesting that modulation of intensity and spatial profile of the beam can be achieved simultaneously under low input intensities in a compact CLC-based micro-device. (paper)

  16. EDUCATION AS A SOCIO-CULTURAL PHENOMENON

    Directory of Open Access Journals (Sweden)

    Victor A. SHTURBA

    2016-01-01

    Full Text Available In the article author analyze the socio-cultural phenomenon of education through the prism of its values and target components. Understanding of the role and place of education in society is not possible out of the human essence context. In living nature man appears as a phenomenon - this thesis is recognized the absolute majoriy of scientific and philosophical theories, concepts and doctrines, including non-humanistic oriented. It is known that man is a social being - society is environment for its full life. As Aristotle said, only the gods and the animals can live outside society. However, human nature does not imply a simple social existence in the form of an intensive exchange of information with similar entities and, based on this, building complex collective actions. The man has a mind that is capable of abstract thought, speech, language, complex psyche, important component of which is imagination. These features formed the basis of theoretical and methodological basis of the analysis of education as a phenomenon. The author indicated value and target measurement of socio-cultural phenomenon of education, which led to the conclusion about the need to rely on a properly organized philosophical and pedagogical knowledge, the importance of implementation in the educational process of program-target approach and the relevance of the audit of modern educational models for nonborrowed trainings, upbringing and socialization. doi: 10.17748/2075-9908-2016-8-2/1-124-126. [en

  17. Left renal vein compression syndrome ("nutcracker phenomenon").

    Science.gov (United States)

    Stassen, C M; Weil, E H; Janevski, B K

    1989-06-01

    Four cases are presented with clinical diagnosis of scrotal varicocele on the left side, and one case with ureter varices and left-sided haematuria as a result of compression of the left renal vein between the aorta and superior mesenteric artery (SMA), also known as "nutcracker phenomenon". The clinical signs and the radiological diagnostic methods of the condition are discussed. PMID:2544950

  18. Left renal vein compression syndrome ('nutcracker phenomenon')

    International Nuclear Information System (INIS)

    Four cases are presented with clinical diagnosis of scrotal varicocele on the left side, and one case with ureter varices and left-sided haematuria as a result of compression of the left renal vein between the aorta and superior mesenteric artery (SMA), also known as 'nutcracker phenomenon'. The clinical signs and the radiological diagnostic methods of the condition are discussed. (orig.)

  19. Bullying: Description and Analysis of the Phenomenon

    Science.gov (United States)

    Benitez, Juan Luis; Justicia, Fernando

    2006-01-01

    This article purports to present this Special Issue about Bullying and, at the same time, to introduce the phenomenon of bullying in order to facilitate readers an updated vision about the problem that will be worked from different perspectives by researchers from national and international scope. With this purpose, we present some controversial…

  20. Mesoscale Phenomenon Revealed by an Acoustic Sounder

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Jensen, Niels Otto

    1976-01-01

    A particular phenomenon observed on an acoustic sounder record is analyzed, and is interpreted as being associated with the passing of a land breeze front. A simple physical explanation of the frontal movements is suggested. The actual existence of the land breeze is demonstrated by examination of...

  1. Methods to Minimize Zero-Missing Phenomenon

    DEFF Research Database (Denmark)

    da Silva, Filipe Miguel Faria; Bak, Claus Leth; Gudmundsdottir, Unnur Stella; Wiechowski, W.; Knardrupgård, M. R.

    2010-01-01

    With the increasing use of high-voltage AC cables at transmission levels, phenomena such as current zero-missing start to appear more often in transmission systems. Zero-missing phenomenon can occur when energizing cable lines with shunt reactors. This may considerably delay the opening of the ci...

  2. Fujita phenomenon in inhomogeneous fast diffusion system

    Science.gov (United States)

    Yang, Jinge; Zheng, Sining; Qu, Chengyuan

    2013-04-01

    This paper deals with the Fujita phenomenon for the Cauchy problem of an inhomogeneous fast diffusion system. Both the critical exponent and the second exponent are obtained. We observe that the inhomogeneous terms in the system substantially contribute to the critical exponent, in that the blow-up exponent region is obviously enlarged, with keeping the second critical exponent unchanged for small inhomogeneous sources.

  3. Convex mappings on some circular domains

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper,we consider some circular domains.And we give an extension theorem for some normalized biholomorphic convex mapping on some circular domains.Especially,we discover the normalized biholomorphic convex mapping on some circular domains have the form f(z) =(f1(z1),...,fn(zn)),where fj:D → C are normalized biholomorphic convex mapping.

  4. Energy dissipation in circular tube

    Directory of Open Access Journals (Sweden)

    A.D. Girgidov

    2012-01-01

    Full Text Available Energy dissipation distribution along the circular tube radius is important in solving such problems as calculation of heat transfer by the air flow through building envelope; calculation of pressure loss in spiral flows; calculation of cyclones with axial and tangential supply of dust-containing gas.Two types of one-dimensional radially axisymmetric flows in circular tube were considered: axial flow and rotation about the axis (Rankine vortex. Relying on two- and four-layer description of axial turbulent flow energy dissipation was calculated in each layer.Similar calculation for Rankine vortex with viscous sublayer at the tube surface was provided. By employing the dissipation minimum principle the boundary radius between rigid rotation and free vortex is calculated. Approximation of the velocity distribution in Rankine vortex is proposed.

  5. Capacitance of circular patch resonator

    International Nuclear Information System (INIS)

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants

  6. Capacitance of circular patch resonator

    Energy Technology Data Exchange (ETDEWEB)

    Miano, G.; Verolino, L. [Dip. di Ingegneria Elettrica, Ist. Nazionale di Fisica Nucleare, Naples (Italy); Panariello, G. [Dip. di Ingegneria Elettronica, Naples (Italy); Vaccaro, V.G. [Ist. Nazionale di Fisica Nucleare, Naples (Italy). Dipt. di Scienze Fisiche

    1995-11-01

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants.

  7. Longitudinal motion in circular accelerators

    International Nuclear Information System (INIS)

    A general description is given of the longitudinal motion of an idealized synchronous particle, exactly in step with the radiofrequency field of a circular accelerator, and a domain in phase and energy, called a bucket, around this particle within which particles are focused around the synchronous particle. This general picture is then made more precise and quantitative. The equations of longitudinal motion and their solutions and the resulting motion are discussed, followed by applications and amplication of the theory. 7 refs., 8 figs

  8. Circular Polarization in Pulsar Integrated Profiles: Updates

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We update the systematic studies of circular polarization in integrated pulse profiles by Han et al. Data of circular polarization profiles are compiled. Sense reversals can occur in core or cone components, or near the intersection between components. The correlation between the sense of circular polarization and the sense of position angle variation for conal-double pulsars is confirmed with a much large database. Circular polarization of some pulsars has clear changes with frequency.Circular polarization of millisecond pulsars is marginally different from that of normal pulsars.

  9. Total positive curvature of circular DNA

    DEFF Research Database (Denmark)

    Bohr, Jakob; Olsen, Kasper Wibeck

    2013-01-01

    micro-DNAs longer than the minimum length must be concave, a result that is consistent with typical atomic force microscopy images of plasmids. Predictions for the total positive curvature of circular micro-DNAs are given as a function of length, and comparisons with circular DNAs from the literature...... molecules, e.g., plasmids, it is shown to have implications for the total positive curvature integral. For small circular micro-DNAs it follows as a consequence of Fenchel's inequality that there must exist a minimum length for the circular plasmids to be double stranded. It also follows that all circular...

  10. Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Assmann, W., E-mail: walter.assmann@lmu.de; Reinhardt, S.; Lehrack, S.; Edlich, A.; Thirolf, P. G.; Parodi, K. [Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748 (Germany); Kellnberger, S.; Omar, M.; Ntziachristos, V. [Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764 (Germany); Moser, M.; Dollinger, G. [Institute for Applied Physics and Measurement Technology, Universität der Bundeswehr, Werner-Heisenberg-Weg 39, Neubiberg 85577 (Germany)

    2015-02-15

    Purpose: Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam. Methods: A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE. Results: In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10{sup 12} eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations. Conclusions: The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound

  11. Monte Carlo Simulation of the Crossover from Bose Glass to Bragg Glass Phase in Layered BSCCO with Columnar Defects

    CERN Document Server

    Queiroz, L M

    2016-01-01

    Monte Carlo simulations of layered BSCCO samples are used to investigate the behavior of vortex matter at low fields, particularly in connection with the possible occurrence of a Bragg glass (BrG) phase at low density of columnar defects, a phenomenon characterized by the prevalence of short-range over long-range order. In this dislocation-free topological phase the translational order correlation function displays a power law decay. For magnetic induction $B=0.1$ kG the analysis of the data for the first Bragg peak of the planar structure factor, the hexatic order parameter, and the Delaunay triangulation shows that, as the density of columnar defects is lowered, a \\textit{crossover} (or transition) from Bose glass to BrG phase takes place in this \\textit{highly anisotropic} high-T${}_c$ superconductor. Most importantly, an analysis of the 3D vortex-vortex correlation function in terms of the structure factor, calculated via a saddle point approach and the use of the numerical data as input, provides clear-c...

  12. Phase transition phenomenon: A compound measure analysis

    Science.gov (United States)

    Kang, Bo Soo; Park, Chanhi; Ryu, Doojin; Song, Wonho

    2015-06-01

    This study investigates the well-documented phenomenon of phase transition in financial markets using combined information from both return and volume changes within short time intervals. We suggest a new measure for the phase transition behaviour of markets, calculated as a return distribution conditional on local variance in volume imbalance, and show that this measure successfully captures phase transition behaviour under various conditions. We analyse the intraday trade and quote dataset from the KOSPI 200 index futures, which includes detailed information on the original order size and the type of each initiating investor. We find that among these two competing factors, the submitted order size yields more explanatory power on the phenomenon of market phase transition than the investor type.

  13. The phenomenon of fluorescence in immunosensors.

    Science.gov (United States)

    Kłos-Witkowska, Aleksandra

    2016-01-01

    The phenomenon of fluorescence in immunosensors is described in this paper. Both structure and characteristics of biosensors and immunosensors are presented. Types of immunosensors and the response of bioreceptor layers to the reaction with analytes as well as measurements of electrochemical, piezoelectric and optical parameters in immunosensors are also presented. In addition, detection techniques used in studies of optical immunosensors based on light-matter interactions (absorbance, reflectance, dispersion, emission) such as: UV/VIS spectroscopy, reflectometric interference spectroscopy (RIfs), surface plasmon resonance (SPR), optical waveguide light-mode spectroscopy (OWLS), fluorescence spectroscopy. The phenomenon of fluorescence in immunosensors and standard configurations of immunoreactions between an antigen and an antibody (direct, competitive, sandwich, displacement) is described. Fluorescence parameters taken into account in analyses and fluorescence detection techniques used in research of immunosensors are presented. Examples of immunosensor applications are given. PMID:27192088

  14. Dissymmetric flow phenomenon in a multistrand tundish

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The dissymmetric flow phenomenon exists in a symmetric multistrand tundish. It was studied by the physical simulation experiment. The fundamental flow characteristic of dissymmetry was analyzed. The asymmetry of the flow field, the temperature field, and the inclusions distribution without flow-control devices (FCDs) were compared with those with FCDs. It is proved that the asymmetry of the flow and temperature field along the outlets at the long range is more obvious. The symmetric FCDs installation has a slight effect on the dissymmetric temperature field, simultaneously, the symmetry of the average residence time and the fluid flow pattern has improved, and the fluid flow in the tundish has been more reasonable. In case of a symmetric multistrand tundish having a large volume, the influence of the dissymmetric phenomenon should be considered and the flow behaviors in the whole tundish should be studied completely.

  15. Multiple steady state phenomenon in martensitic transformation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the basic facts that the martensitic transformation is a physical phenomenon which occurs in non-equilibrium conditions and there exists the feedback mechanism in the martensitic transformation, the dynamical processes of the isothermal and athermal martensitic transformations were analyzed by using nonlinear theory and a bifurcation theory model was established. It is shown that a multiple steady state phenomenon can take place as austenite is cooled, and the transitions of the steady state temperature between the branches of stable steady states can be considered the transformation from austenite to martensite. This model can estimate the starting temperature of the martensitic transformation and explain some experimental features of the martensitic transformation such as the effects of cooling rate, fluctuation and austenitic grain size on the martensitic transformation.

  16. Diffusion phenomenon for linear dissipative wave equations

    KAUST Repository

    Said-Houari, Belkacem

    2012-01-01

    In this paper we prove the diffusion phenomenon for the linear wave equation. To derive the diffusion phenomenon, a new method is used. In fact, for initial data in some weighted spaces, we prove that for {equation presented} decays with the rate {equation presented} [0,1] faster than that of either u or v, where u is the solution of the linear wave equation with initial data {equation presented} [0,1], and v is the solution of the related heat equation with initial data v 0 = u 0 + u 1. This result improves the result in H. Yang and A. Milani [Bull. Sci. Math. 124 (2000), 415-433] in the sense that, under the above restriction on the initial data, the decay rate given in that paper can be improved by t -γ/2. © European Mathematical Society.

  17. Distribution of Micronuclei in Human Fibroblasts across the Bragg Curve of Light and Heavy Ions

    Science.gov (United States)

    Hada, M.; Lacy, S.; Gridley, D. S.; Rusek, A.; Cucinotta, F. A.; Wu, H.

    2007-01-01

    The space environment consists of energetic particles of varying mass and energy, and understanding the :biological Bragg curve" is essential in optimizing shielding effectiveness against space radiation induced biological impacts. The "biological Bragg curve" is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Previously, we studied the induction of micronuclei (MN) across the Bragg curve of energetic Fe and Si ions, and observed no increased yield of MN at the location of the Bragg peak. However, the ratio of mono- to bi-nucleated cells, which indicates inhibition of cell progression, was found higher at the Bragg peak location in comparison to the plateau region of the Bragg curve. Here, we report the induction of MN in normal human fibroblast cells across the Bragg curve of incident protons generated at Loma Linda University. Similar to Si and Fe ions, the ratio of mono- to bi-nucleated cells showed a clear spike as the protons reached the Bragg peak. Unlike the two heavy ions, however, the MN yield also increased at the Bragg peak location. These results confirm the hypothesis that severely damaged cells at the Bragg peak of heavy, but not light ions are more likely to go through reproductive death and not be evaluated for micronuclei.

  18. Improved Phase-Mask Fabrication of Fiber Bragg Gratings

    Science.gov (United States)

    Grant, Joseph; Wang, Ying; Sharma, Anup

    2004-01-01

    An improved method of fabrication of Bragg gratings in optical fibers combines the best features of two prior methods: one that involves the use of a phase mask and one that involves interference between the two coherent laser beams. The improved method affords flexibility for tailoring Bragg wavelengths and bandwidths over wide ranges. A Bragg grating in an optical fiber is a periodic longitudinal variation in the index of refraction of the fiber core. The spatial period (Bragg wavelength) is chosen to obtain enhanced reflection of light of a given wavelength that would otherwise propagate relatively unimpeded along the core. Optionally, the spatial period of the index modulation can be made to vary gradually along the grating (such a grating is said to be chirped ) in order to obtain enhanced reflection across a wavelength band, the width of which is determined by the difference between the maximum and minimum Bragg wavelengths. In the present method as in both prior methods, a Bragg grating is formed by exposing an optical fiber to an ultraviolet-light interference field. The Bragg grating coincides with the pattern of exposure of the fiber core to ultraviolet light; in other words, the Bragg grating coincides with the interference fringes. Hence, the problem of tailoring the Bragg wavelength and bandwidth is largely one of tailoring the interference pattern and the placement of the fiber in the interference pattern. In the prior two-beam interferometric method, a single laser beam is split into two beams, which are subsequently recombined to produce an interference pattern at the location of an optical fiber. In the prior phase-mask method, a phase mask is used to diffract a laser beam mainly into two first orders, the interference between which creates the pattern to which an optical fiber is exposed. The prior two-beam interferometric method offers the advantage that the period of the interference pattern can be adjusted to produce gratings over a wide range

  19. Love Phenomenon and Neurobiology of Love Relations

    OpenAIRE

    Tufan, Ali Evren; Yaluğ, İrem

    2010-01-01

    The biology; especially the neurobiological features of the �love� phenomenon has recently started to attract attention. Love relations and attachment, which is closely related with them, are known to be important in health and disease. Love and love relations are found to be complex neurobiological phenomena based on activation of the limbic system of the brain. Those processes involve oxytocin, vasopressin, dopamine and serotonergic functions. Additionally, endorphine ...

  20. Phenomenon, noumenon, and mind in Kant

    OpenAIRE

    Alejandro Rosas

    1996-01-01

    The Cartesian substantial dualism and the mind-body problem provoked in the Modern Times a monist reaction that eliminated the ontological dualist interaction and conceived the problem as a conflict between explanatory discourses. Kant introduces the distinction between phenomenon and noumenon as one of perspective, with the intention of solving the conflict between materialist and mentalist explanations. However, he does not consistently place the mind in the noumenic perspective and thus bl...

  1. 2. The Central American gang phenomenon

    OpenAIRE

    Does, Antonia

    2013-01-01

    2.1. Differentiating between pandillas and maras Youth gangs have existed since the 1960s and 1970s in Central America. However, there are different types of Central American gangs and thus one has to distinguish between pandillas and maras. The former are localized, homegrown gangs, which are “direct inheritors” (Jütersonke, Rodgers & Muggah 2009: 379) of the gangs that have historically characterized Central American societies, while the latter are a more recent phenomenon with transnationa...

  2. NANOLEAKAGE PHENOMENON ON DEPROTEINIZED HUMAN DENTIN

    OpenAIRE

    Patrícia de Britto Pereira Garcia Duarte; Eduardo Moreira da Silva

    2007-01-01

    OBJECTIVE: The purpose of this study was to evaluate the influence of dentin deproteinization on the nanoleakage phenomenon. MATERIAL AND METHODS: Class V cavities were prepared in 12 human molars with cervical margins located in dentin. The cavities were assigned to 2 groups (n=6) according to dentin treatment: Group I - dentin treated in accordance with the manufacturer's instructions and Group II - dentin treated following the manufacturer's instructions + 10% NaOCl. Each group was sub-div...

  3. Prebiotic homochirality as a critical phenomenon.

    Science.gov (United States)

    Gleiser, Marcelo; Thorarinson, Joel

    2006-12-01

    The development of prebiotic homochirality on early-Earth or another planetary platform may be viewed as a critical phenomenon. It is shown, in the context of spatio-temporal polymerization reaction networks, that environmental effects--be they temperature surges or other external disruptions--may destroy any net chirality previously produced. In order to understand the emergence of prebiotic homochirality it is important to model the coupling of polymerization reaction networks to different planetary environments. PMID:17120129

  4. Prebiotic Homochirality as a Critical Phenomenon

    CERN Document Server

    Gleiser, M; Gleiser, Marcelo; Thorarinson, Joel

    2006-01-01

    The development of prebiotic homochirality on early-Earth or another planetary platform may be viewed as a critical phenomenon. It is shown, in the context of spatio-temporal polymerization reaction networks, that environmental effects -- be them temperature surges or other external disruptions -- may destroy any net chirality previously produced. In order to understand the emergence of prebiotic homochirality it is important to model the coupling of polymerization reaction networks to different planetary environments.

  5. Prebiotic Homochirality as a Critical Phenomenon

    OpenAIRE

    Gleiser, Marcelo; Thorarinson, Joel

    2006-01-01

    The development of prebiotic homochirality on early-Earth or another planetary platform may be viewed as a critical phenomenon. It is shown, in the context of spatio-temporal polymerization reaction networks, that environmental effects -- be them temperature surges or other external disruptions -- may destroy any net chirality previously produced. In order to understand the emergence of prebiotic homochirality it is important to model the coupling of polymerization reaction networks to differ...

  6. Cyberbullying as a modern phenomenon of ICT

    OpenAIRE

    Vlk, Jan

    2013-01-01

    This bachelor work summarizes the problem known as cyberbullying. It is a problem about last two decades, coupled with the rapid development of communication technology and the rapprochement of communications equipment to children and youth. Cyberbullying is the phenomenon of limiting user rights through the Internet. Typically it is the ridicule, humiliation and reducing of user dignity. The work monitors cyberbullying from the perspective of the aggressor (producer) and victims. The proces...

  7. Tax Culture as Tax Administration Staff Phenomenon

    OpenAIRE

    Viktor Synchak

    2013-01-01

    The concept of the tax culture has been grounded. Various approaches to the tax culture have been highlighted. The ambiguous aspects of the tax culture approaches and interpretation have been pointed out. The authors have also given the definition of the tax body officials' culture. The tax culture has been defined as a special kind of tax service employee's culture. The necessity of the tax culture phenomenon to be familiarized with by every tax official prior to their employment has been pr...

  8. THE LUXURY PHENOMENON - THE GLOBALIZATION OF VARIETY

    OpenAIRE

    Murali Murti

    2010-01-01

    Our contemporary understanding of globalization is an increasing interlinking and interdependence of national economies within a global economy. This view of globalization has become associated with large corporations driven by their own immediate self-interests. This process is seen as leading to an increasingly homogenous global culture. This can be described as the globalization of uniformity. The globalization of uniformity is most often identified with the phenomenon of outsourcing, and ...

  9. Animal Rights as a Mainstream Phenomenon

    OpenAIRE

    Rollin, Bernard E.

    2011-01-01

    Simple Summary The twentieth century has witnessed a bewildering array of ethical revolutions, from civil rights to environmentalism to feminism. Often ignored is the rise of massive societal concern across the world regarding animal treatment. Regulation of animal research exists in virtually all western countries, and reform of “factory farming” is regnant in Europe and rapidly emerging in the United States. Opponents of concern for animals often dismiss the phenomenon as rooted in emotion ...

  10. Earnings Management: Obvious Phenomenon in Albanian Market

    OpenAIRE

    Teuta Llukani; Vjollca Karapici

    2013-01-01

    Fiscal earnings, measures the performance of the company during the financial year. Motivated by different factors such as those related to the capital market, contractual motives etc, managers can manipulate earnings, increasing or reducing them and this phenomenon is recognized as “earnings management”. If we accept that the initiatives of “earnings management” lead to distortion of the financial results, it means that financial reports can be considered as poor quality reports, and financi...

  11. Characterizing the phenomenon of radiation recall dermatitis

    International Nuclear Information System (INIS)

    Radiation recall represents the 'recalling' of an effect similar in appearance to that of an acute radiation reaction in a previously irradiated field. The recall is triggered by the administration of certain drugs days to years after the exposure to ionizing radiation. This review focuses almost exclusively on the skin manifestations of radiation recall to assemble the largest data base upon which to discuss this rare phenomenon. No absolute radiation dose threshold is apparent, but rather an interplay between dose and time before drug exposure seems to affect both the risk and speed of onset of recall. Recall usually occurs on first exposure to a particular recall-triggering drug. The skin reaction develops within minutes to days. The time to develop the reaction may be slightly longer for oral than intravenously administered drugs reflecting their bioavailability. Most drugs associated with recall are cytotoxics, but several other drugs may elicit the phenomenon. Individuals exposed to a number of potentially recall-triggering drugs reveal the marked drug specificity characteristic of the phenomenon. Skin reactions usually settle within a few days of stopping the triggering drug. The role of steroids or anti-histamines in affecting resolution is unclear. Drug rechallenge tends to produce either only a mild recurrence or no recurrence of recall. Steroids or dose reduction may favour uneventful rechallenge. A number of aetiological hypotheses on radiation recall exist. Using the available evidence these hypotheses are critically reviewed and a novel hypothesis based on radiation affecting local cutaneous immunological responses proposed

  12. Andreev-Bragg Reflection from an Amperian Superconductor

    Science.gov (United States)

    Baireuther, P.; Hyart, T.; Tarasinski, B.; Beenakker, C. W. J.

    2015-08-01

    We show how an electrical measurement can detect the pairing of electrons on the same side of the Fermi surface (Amperian pairing), recently proposed by Patrick Lee for the pseudogap phase of high-Tc cuprate superconductors. Bragg scattering from the pair-density wave introduces odd multiples of 2 kF momentum shifts when an electron incident from a normal metal is Andreev reflected as a hole. These Andreev-Bragg reflections can be detected in a three-terminal device, containing a ballistic Y junction between normal leads (1, 2) and the superconductor. The cross-conductance d I1/d V2 has the opposite sign for Amperian pairing than it has either in the normal state or for the usual BCS pairing.

  13. Bragg-peak spectroscopy of low-energy heavy ions

    International Nuclear Information System (INIS)

    A small axial ionization chamber with the electric field lines parallel to the particle trajectory (Bragg ionization chamber) allowing the determination of the nuclear charge and the energy of low energetic low mass heavy ions (E/A approximately 0.8 - 2.0 MeV/amu) is presented together with an adapted shaping amplifier. Using the usual technique of pulse shaping with a long and a short time constant the energy and the Bragg peak resolutions for projectiles between 24He and 1632S were determined. With commercially available low purity n-pentane purified from water and oxygene by a threefold destillation an energy resolution of ΔE/E = 1% and a charge resolving power of Z/ΔZ = 47 are attainable for 41.4 MeV 28Si ions elastically scattered from 197Au. No significant pulse height defect is observable for the energy determination of particles with Z <= 17. (author)

  14. Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

    Science.gov (United States)

    Carman, Gregory P. (Inventor); Emmons, Michael C. (Inventor); Richards, William Lance (Inventor); Mohanchandra, Panduranga K. (Inventor)

    2016-01-01

    The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

  15. Self-aligned Coupled Waveguide Distributed Bragg Reflector Lasers

    Institute of Scientific and Technical Information of China (English)

    LIU Guoli; WANG Wei; ZHU Hongliang; ZHANG Jingyuan; HU Xiaohua; LU Yu; ZHANG Jing

    2002-01-01

    A novel self-aligned coupled waveguide (SACW) multi-quantum-well (MQW) distributed Bragg reflector (DBR) laser is proposed and demonstrated for the first time. By selectively removing the MQW layer and leaving the low SCH/SACW layer the Bragg grating is partially formed on this layer. By optimizing the thickness of the low SCH/SACW layer, a~80% coupling efficiency between the MQW gain region and the passive region are obtained. The typical threshold current of the SACW DBR laser is 39 mA, the slope efficiency can reach to 0.2 mW/mA and the output power is more than 20 mW with a more than 30dB side mode suppression ratio.

  16. Processing of Signals from Fiber Bragg Gratings Using Unbalanced Interferometers

    Science.gov (United States)

    Adamovsky, Grigory; Juergens, Jeff; Floyd, Bertram

    2005-01-01

    Fiber Bragg gratings (FBG) have become preferred sensory structures in fiber optic sensing system. High sensitivity, embedability, and multiplexing capabilities make FBGs superior to other sensor configurations. The main feature of FBGs is that they respond in the wavelength domain with the wavelength of the returned signal as the indicator of the measured parameter. The wavelength is then converted to optical intensity by a photodetector to detect corresponding changes in intensity. This wavelength-to-intensity conversion is a crucial part in any FBG-based sensing system. Among the various types of wavelength-to-intensity converters, unbalanced interferometers are especially attractive because of their small weight and volume, lack of moving parts, easy integration, and good stability. In this paper we investigate the applicability of unbalanced interferometers to analyze signals reflected from Bragg gratings. Analytical and experimental data are presented.

  17. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Hu, Xiaolian; Saez-Rodriguez, D.; Bang, Ole;

    2014-01-01

    Step-index polymer optical fiber Bragg gratings (POFBGs) and microstructured polymer optical fiber Bragg gratings (mPOFBGs) present several attractive features, especially for sensing purposes. In comparison to FBGs written in silica fibers, they are more sensitive to temperature and pressure...... because of the larger thermo-optic coefficient and smaller Young's modulus of polymer materials. (M)POFBGs are most often photowritten in poly(methylmethacrylate) (PMMA) materials using a continuous-wave 325 nm HeCd laser. For the first time to the best of our knowledge, we study photoinduced...... birefringence effects in (m)POFBGs. To achieve this, highly reflective gratings were inscribed with the phase mask technique. They were then monitored in transmission with polarized light. For this, (m)POF sections a few cm in length containing the gratings were glued to angled silica fibers. Polarization...

  18. Andreev-Bragg Reflection from an Amperian Superconductor.

    Science.gov (United States)

    Baireuther, P; Hyart, T; Tarasinski, B; Beenakker, C W J

    2015-08-28

    We show how an electrical measurement can detect the pairing of electrons on the same side of the Fermi surface (Amperian pairing), recently proposed by Patrick Lee for the pseudogap phase of high-Tc cuprate superconductors. Bragg scattering from the pair-density wave introduces odd multiples of 2k(F) momentum shifts when an electron incident from a normal metal is Andreev reflected as a hole. These Andreev-Bragg reflections can be detected in a three-terminal device, containing a ballistic Y junction between normal leads (1, 2) and the superconductor. The cross-conductance dI1/dV2 has the opposite sign for Amperian pairing than it has either in the normal state or for the usual BCS pairing. PMID:26371674

  19. Planar Bragg Grating Sensors—Fabrication and Applications: A Review

    Directory of Open Access Journals (Sweden)

    I. J. G. Sparrow

    2009-01-01

    Full Text Available We discuss the background and technology of planar Bragg grating sensors, reviewing their development and describing the latest developments. The physical operating principles are discussed, relating device operation to user requirements. Recent performance of such devices includes a planar Bragg grating sensor design which allows refractive index resolution of 1.9×10−6 RIU and temperature resolution of 0.03∘C. This sensor design is incorporated into industrialised applications allowing the sensor to be used for real time sensing in intrinsically safe, high-pressure pipelines, or for insertion probe applications such as fermentation. Initial data demonstrating the ability to identify solvents and monitor long term industrial processes is presented. A brief review of the technology used to fabricate the sensors is given along with examples of the flexibility afforded by the technique.

  20. Fiber Bragg grating strain sensors for marine engineering

    Science.gov (United States)

    Wang, Tingting; Yuan, Zilin; Gong, Yuan; Wu, Yu; Rao, Yunjiang; Wei, Lili; Guo, Peng; Wang, Junpu; Wan, Fu

    2013-09-01

    For the health monitoring of the offshore drilling platform in the salt-fog environment, three nonmetallic materials, i.e., silica, FR-4 epoxy board and sheet molding compound (SMC), with the good anti-corrosion ability were chosen as the packaging materials for the fiber Bragg grating (FBG) strain sensors. By selecting a highly sensitive structure of the fiber Bragg grating strain sensor, the performances of the sensors with three materials were investigated both numerically and experimentally. The strain sensitivities were 3.76 pm/μɛ, 3.02 pm/μɛ and 3.03 pm/μɛ, respectively. The linearity was better than 0.998. It provides useful information for developing sensors for the marine engineering.

  1. Energy-dispersive phase plate for magnetic circular dichroism experiments in the X-ray range

    International Nuclear Information System (INIS)

    A 220 diamond phase plate was combined with an energy-dispersive absorption spectrometer to convert linearly polarized X-rays into circularly polarized photons and to detect circular magnetic X-ray dichroism (CMXD) from ferromagnetic samples. In these experiments, carried out at LURE, the energy-dispersive spectrometer was equipped with a bent Si (311) polychromator and vertically collimating slits accepting essentially a linearly polarized incident beam. The quarter-wave plate was operated in the Bragg geometry but well outside the range of quasi total reflection, with the consequence that the forward-diffracted beam was circularly polarized with a polarization rate approaching 80% over the whole energy bandpass of the polychromator. CMXD spectra of GdFe2 and GdCo2 intermetallic compounds were recorded at ca 7.2 keV near the Gd LIII absorption edge: they are essentially identical to the spectra commonly recorded with elliptically polarized X-ray photons collected out of the orbit plane of the storage ring. It is suggested that the energy-dispersive phase plate will be very useful to detect CMXD spectra with energy-dispersive spectrometers exploiting the well collimated linearly polarized emission of standard undulators installed on the storage rings of the third generation. (orig.)

  2. Photonic crystal distributed feedback fiber lasers with Bragg gratings

    DEFF Research Database (Denmark)

    Søndergaard, Thomas

    2000-01-01

    Two new types of optical fibers, where air-holes are running down their length, are considered for making fiber lasers with Bragg gratings. The mode areas for pump and signal in these fiber lasers may be either larger or smaller compared to the corresponding mode areas for fiber lasers based on...... standard step index fibers. This makes possible realization of fiber lasers with a low pump threshold (small mode area), and fiber lasers suitable for high-power applications (large mode area)...

  3. DESIGN AND SIMULATION OF FIBER BRAGG GRATING BASED SENSORS

    OpenAIRE

    MOHAMED M. SALEH; RIADH K. A. Al-ANI; ILHAM K. ONEES

    2014-01-01

    In this paper the temperature and strain sensing principle of FBG based sensors are design & simulated by using Optigrating software. Simulation tools provide valuable help in optimizing the design parameters.From the graphical simulations, it can be concluded that there is a linear relationship between the Bragg wavelength shift and the temperature as well as the strain change. Also different values of grating period due to increasing the value of shifted wavelength.

  4. Simulation of Novel Tunable Nonlinear Chirped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-min; YU Zhong-yuan; ZHANG Xiao-guang; YU Li; YANG Bo-jun

    2003-01-01

    A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.

  5. Trial analysis of swine's periodontal ligament with Bragg grating sensors

    Science.gov (United States)

    Menegotto, G. F.; Grabarski, L.; Kalinowski, H. J.; Simões, J. A.

    2009-10-01

    In this work it is reported the measurement of the differential strain between the dental and bone tissues under effect of an applied load. Slices of swine mandible, containing the premolar tooth, are cut and measured in fresh condition. The strain is measured using fibre Bragg grating sensors glued to both tissues. In the measured range the results show a linear behaviour and confirm the importance of the periodontal ligament in the load transfer mechanism.

  6. Bragg optics computer codes for neutron scattering instrument design

    Energy Technology Data Exchange (ETDEWEB)

    Popovici, M.; Yelon, W.B.; Berliner, R.R. [Missouri Univ. Research Reactor, Columbia, MO (United States); Stoica, A.D. [Institute of Physics and Technology of Materials, Bucharest (Romania)

    1997-09-01

    Computer codes for neutron crystal spectrometer design, optimization and experiment planning are described. Phase space distributions, linewidths and absolute intensities are calculated by matrix methods in an extension of the Cooper-Nathans resolution function formalism. For modeling the Bragg reflection on bent crystals the lamellar approximation is used. Optimization is done by satisfying conditions of focusing in scattering and in real space, and by numerically maximizing figures of merit. Examples for three-axis and two-axis spectrometers are given.

  7. Large-momentum-transfer Bragg interferometer with strontium atoms

    CERN Document Server

    Mazzoni, T; Del Aguila, R; Salvi, L; Poli, N; Tino, G M

    2015-01-01

    We report on the first atom interferometer based on Bragg diffraction in a fountain of alkaline-earth atoms, namely $^{88}$Sr. We demonstrate large momentum transfer to the atoms up to eight photon recoils and the use of the interferometer as a gravimeter with a sensitivity $\\delta g/g=4\\times 10^{-8}$. Thanks to the special characteristics of strontium atoms for precision measurements, this result opens a new way for experiments in fundamental and applied physics.

  8. Boron-doped superlattices and Bragg mirrors in diamond

    OpenAIRE

    Fiori, Alexandre; Bousquet, Jessica; Eon, David; Omnès, Franck; Bellet-Amalric, E.; Bustarret, Etienne

    2014-01-01

    International audience A periodic modulation of the boron doping level of single crystal diamond multilayers over more than three orders of magnitude during epitaxial growth by microwave plasma-enhanced chemical vapor deposition is shown to yield Bragg mirrors in the visible. The thicknesses and doping level of the individual layers were controlled by in situ spectroscopic ellipsometry, enabling to tune the reflec-tance peak to the wavelength range of diamond color centers, such as NV 0 or...

  9. Fiber Bragg Gratings Embedded in 3D-Printed Scaffolds

    CERN Document Server

    Liacouras, Peter; Choudhry, Khazar; Strouse, G F; Ahmed, Zeeshan

    2015-01-01

    In recent years there has been considerable interest in utilizing embedded fiber optic based sensors for fabricating smart materials. One of the primary motivations is to provide real-time information on the structural integrity of the material so as to enable proactive actions that prevent catastrophic failure. In this preliminary study we have examined the impact of embedding on the temperature-dependent response of fiber Bragg gratings.

  10. A new generation of multilayer Bragg-Fresnel lenses

    International Nuclear Information System (INIS)

    A new type of Bragg-Fresnel multilayer lens (BFML) have been fabricated at IMT RAS and tested at LURE. The idea to combine different diffraction orders of a zone plate in one focal spot introduced by Simpson and Michette has been realized in a BFML with extended aperture. Matching of the two diffraction orders, the first and third, into one focal plane increases the output flux by a factor of two and the spatial resolution in the same order of magnitude

  11. Degradation of the Bragg peak due to inhomogeneities.

    Science.gov (United States)

    Urie, M; Goitein, M; Holley, W R; Chen, G T

    1986-01-01

    The rapid fall-off of dose at the end of range of heavy charged particle beams has the potential in therapeutic applications of sparing critical structures just distal to the target volume. Here we explored the effects of highly inhomogeneous regions on this desirable depth-dose characteristic. The proton depth-dose distribution behind a lucite-air interface parallel to the beam was bimodal, indicating the presence of two groups of protons with different residual ranges, creating a step-like depth-dose distribution at the end of range. The residual ranges became more spread out as the interface was angled at 3 degrees, and still more at 6 degrees, to the direction of the beam. A second experiment showed little significant effect on the distal depth-dose of protons having passed through a mosaic of teflon and lucite. Anatomic studies demonstrated significant effects of complex fine inhomogeneities on the end of range characteristics. Monoenergetic protons passing through the petrous ridges and mastoid air cells in the base of skull showed a dramatic degradation of the distal Bragg peak. In beams with spread out Bragg peaks passing through regions of the base of skull, the distal fall-off from 90 to 20% dose was increased from its nominal 6 to well over 32 mm. Heavy ions showed a corresponding degradation in their ends of range. In the worst case in the base of skull region, a monoenergetic neon beam showed a broadening of the full width at half maximum of the Bragg peak to over 15 mm (compared with 4 mm in a homogeneous unit density medium). A similar effect was found with carbon ions in the abdomen, where the full width at half maximum of the Bragg peak (nominally 5.5 mm) was found to be greater than 25 mm behind gas-soft-tissue interfaces. We address the implications of these data for dose computation with heavy charged particles. PMID:3952143

  12. A high sensitive fiber Bragg grating cryogenic temperature sensor

    Institute of Scientific and Technical Information of China (English)

    Kuo Li; Zhen'an Zhou; Aichun Liu

    2009-01-01

    At cryogenic temperature, a fiber Bragg grating (FBG) temperature sensor with controllable sensitivity and variable measurement range is demonstrated by using bimetal configuration. In experiments, sensitivities of -51.2, -86.4, and -520 pm/K are achieved by varying the lengths of the metals. Measurement ranges of 293 - 290.5, 283 - 280.5, and 259 - 256.5 K are achieved by shortening the distance of the gap among the metals.

  13. Underwater Acoustic Sensors Based on Fiber Bragg Gratings

    OpenAIRE

    Giuseppe Parente; Giuseppe Lanza; Armando Laudati; Michele Giordano; Andrea Cusano; Stefania Campopiano; Antonello Cutolo

    2009-01-01

    We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating) under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, sho...

  14. Measurement of sensors with fiber Bragg gratings by laser interferometer

    Czech Academy of Sciences Publication Activity Database

    Mikel, Břetislav; Čížek, Martin; Řeřucha, Šimon; Číp, Ondřej

    Budva : University of Montenegro, 2013. s. 47. [ALT´13. Annual International Conference on Advanced Laser Technologies /21./. 16.09.2013-20.09.2013, Budva] R&D Projects: GA MŠk ED0017/01/01; GA TA ČR TA01010995; GA TA ČR(CZ) TA03010835 Institutional support: RVO:68081731 Keywords : fiber Bragg sensors * laser interferometry * optical spectrum analysis * fiber sensors Subject RIV: BH - Optics, Masers, Laser s

  15. Calibration of elongation of fiber Bragg gratings by laser interferometer

    Czech Academy of Sciences Publication Activity Database

    Mikel, Břetislav; Čížek, Martin; Holík, M.; Číp, Ondřej

    Bellingham : SPIE, 2013, 89161I:1-6. ISSN 0277-786X. [International Symposium on Precision Mechanical Measurements /6./. Guiyang (CN), 10.10.2013] R&D Projects: GA MŠk ED0017/01/01; GA TA ČR TA01010995; GA TA ČR(CZ) TA03010835; GA MV VG20132015124 Institutional support: RVO:68081731 Keywords : Fiber Bragg gratings * Interferometers * Laser s * Optical fibers * Buildings Subject RIV: BH - Optics, Masers, Laser s

  16. Deterministic Circular Self Test Path

    Institute of Scientific and Technical Information of China (English)

    WEN Ke; HU Yu; LI Xiaowei

    2007-01-01

    Circular self test path (CSTP) is an attractive technique for testing digital integrated circuits(IC) in the nanometer era, because it can easily provide at-speed test with small test data volume and short test application time. However, CSTP cannot reliably attain high fault coverage because of difficulty of testing random-pattern-resistant faults. This paper presents a deterministic CSTP (DCSTP) structure that consists of a DCSTP chain and jumping logic, to attain high fault coverage with low area overhead. Experimental results on ISCAS'89 benchmarks show that 100% fault coverage can be obtained with low area overhead and CPU time, especially for large circuits.

  17. High frequency strain measurements with fiber Bragg grating sensors

    Science.gov (United States)

    Koch, J.; Angelmahr, M.; Schade, W.

    2015-05-01

    In recent years fiber Bragg grating sensors gained interest in structural health monitoring and concepts for smart structures. They are small, lightweight, and immune to electromagnetic interference. Using multiplexing techniques, several sensors can be addressed by a single fiber. Therefore, well-established structures and materials in industrial applications can be easily equipped with fiber optical sensors with marginal influence on their mechanical properties. In return, critical components can be monitored in real-time, leading to reduced maintenance intervals and a great reduction of costs. Beside of generally condition monitoring, the localization of failures in a structure is a desired feature of the condition monitoring system. Detecting the acoustic emission of a sudden event, its place of origin can be determined by analyzing the delay time of distributed sensor signals. To achieve high localization accuracies for the detection of cracks, breaks, and impacts high sampling rates combined with the simultaneous interrogation of several fiber Bragg grating sensors are required. In this article a fiber Bragg grating interrogator for high frequency measurements up to the megahertz range is presented. The interrogator is based on a passive wavelength to intensity conversion applying arrayed waveguide gratings. Light power fluctuations are suppressed by a differential data evaluation, leading to a reduced signal-to-noise ratio and a low strain detection limit. The measurement system is used to detect, inter alia, wire breaks in steel wire ropes for dockside cranes.

  18. Synchrotron radiation focusing by a Bragg--Fresnel lens

    International Nuclear Information System (INIS)

    Since the discovery of x rays and until the present time the possibilities of their controlling and focusing have been widely discussed. In the hard spectrum region (λ∼1 A) the main focusing schemes are the following: geometrical focusing based on incoherent interaction of wave packets reflected by different regions of bending crystals and coherent (dynamic) focusing performed at the cost of the effect of refraction index angular dispersion near the exact Bragg angle value -θB. A main disadvantage of geometrical focusing is low spatial resolution (∼0.1 mm) and temperature stability. In the case of coherent focusing a main disadvantage is a narrow angular aperture (∼10 sec. of arc) at spatial resolution (∼1--10 μm). Recently, advances in the development of diffraction physics and microstructuring technology open up possibilities for fabricating effective focusing x-ray optical elements---Bragg--Fresnel lenses (BFL)---with high spatial resolution (∼0.1 μm) at a wide angular aperture and high temperature stability. The present paper describes the main principles of Bragg--Fresnel optics (BFO). It presents the results on the synchrotron experiment and on observation of focusing. In this work the peculiarities of BFL diffraction contrast formation are investigated and image transmission using a BFL is performed. Possibilities of developing x-ray optical schemes of ultrahigh resolution on the basis of BFL elements are also discussed

  19. Physics at Future Circular Colliders

    Science.gov (United States)

    Kotwal, Ashutosh

    2016-03-01

    The Large Hadron Collider has been a grand success with the discovery of the Higgs boson, with bright prospects for additional discoveries since the recent increase in collider energy and the anticipated large datasets. Big open questions such as the nature of dark matter, the origin of the matter-antimatter asymmetry in the Universe, and the theoretical puzzle of the finely-tuned parameters in the Higgs sector, demand new physics principles that extend the established Standard Model paradigm. Future circular colliders in a substantially larger tunnel can house both a high luminosity electron-positron collider for precision measurements of Higgs and electroweak parameters, as well as a very high energy proton-proton collider which can directly manifest particles associated with these new physics principles. We discuss the physics goals of these future circular colliders, and the prospects for elucidating fundamental new laws of nature that will significantly extend our understanding of the Universe. Detailed studies of the discovery potential in specific benchmark models will be presented, with implications for detector design.

  20. A Method to Discriminate Strain and Temperature in Fiber Bragg Grating Sensors

    OpenAIRE

    Chalapati, Madhan T; Pattnaik, PK; Selvarajan, A; T. Srinivas

    2005-01-01

    A significant limitation to the applications of fiber Bragg gratings (FBG) sensors is the sensitivity of the Bragg wavelength to both temperature and strain, complicating the independent measurement of these paremeters. In this letter, we explore a new method to discriminate strain and temperature in FBG sensors, which utilises the additioanl wavelength dependent phase introduced by Fiber Bragg grating written on sensing arm of Mach Zehnder Interferometer (MZI). The intensity variations of th...

  1. Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan; HE Xing-Fang; YUAN Jie; YIN Li-Qun; FANG Xiao-Yong; CAO Mao-Sheng

    2009-01-01

    We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating.

  2. Spectral characteristics of draw-tower step-chirped fiber Bragg gratings

    Science.gov (United States)

    Idrisov, Ravil F.; Varzhel, Sergey V.; Kulikov, Andrey V.; Meshkovskiy, Igor K.; Rothhardt, Manfred; Becker, Martin; Schuster, Kay; Bartelt, Hartmut

    2016-06-01

    This paper presents research results on the spectral properties of step-chirped fiber Bragg grating arrays written during the fiber drawing process into a birefringent optical fiber with an elliptical stress cladding. The dependences of resonance shift of the step-chirped fiber Bragg grating on bending, on applied tensile stress and on temperature have been investigated. A usage of such step-chirped fiber Bragg gratings in fiber-optic sensing elements creation has been considered.

  3. SPECTRAL CHARACTERISTIC OF UNIFORM FIBER BRAGG GRATING USING COUPLE MODE THEORY

    Directory of Open Access Journals (Sweden)

    JYOTSNA RANI MAHAPATRA, MANISHA CHATTOPADHYAY

    2013-08-01

    Full Text Available This paper presents spectral characteristic of Fiber Bragg Grating. Here the modeling and simulation of an optical fiber Bragg grating for reflectivity based on coupled mode theory is discussed in details. Grating length represent as one of the important parameters in contributing to a high performance Fiber Bragg Grating. The reflection spectrum is analyzed with different parameters like wavelength, grating lengths and induced index change

  4. Phenomenon, noumenon, and mind in Kant

    Directory of Open Access Journals (Sweden)

    Alejandro Rosas

    1996-06-01

    Full Text Available The Cartesian substantial dualism and the mind-body problem provoked in the Modern Times a monist reaction that eliminated the ontological dualist interaction and conceived the problem as a conflict between explanatory discourses. Kant introduces the distinction between phenomenon and noumenon as one of perspective, with the intention of solving the conflict between materialist and mentalist explanations. However, he does not consistently place the mind in the noumenic perspective and thus blurs his perspectivist solution and ontological commitments to the idealist mentalism. The A. intends to show the plausibility of this hypothetical interpretation.

  5. A cutoff phenomenon for quantum Markov chains

    International Nuclear Information System (INIS)

    We derive upper and lower bounds on the convergence behavior of certain classes of one-parameter quantum dynamical semigroups. The classes we consider, consist of tensor product channels and of channels with commuting Liouvillians. We introduce the notion of cutoff phenomenon in the setting of quantum information theory, and show how it exemplifies the fact that the convergence of (quantum) stochastic processes is not solely governed by the spectral gap of the transition map. We apply the new methods to show that graph states can be prepared efficiently, albeit not in constant time, by dissipation, and give the exact scaling behavior of the time to stationarity. (paper)

  6. Tacit Knowledge as a Cognitive Phenomenon

    Directory of Open Access Journals (Sweden)

    Roman G. Bolbakov

    2016-03-01

    Full Text Available The article analyzes the implicit knowledge as a cognitive phenomenon. The article reveals the content of tacit knowledge. The article reveals the contents of the transformation of tacit knowledge into explicit knowledge. This article describes an inductive approach as a cognitive approach. The article introduces the concept of an information structure for communication and information between cognitive processes. The article substantiates the proposition that cognitive methods and procedures for implementing the process of "socialization". The article proves that the process is a prerequisite for the subsequent externalization, that is, the conversion of tacit knowledge into explicit knowledge.

  7. Statistical analysis of the migration phenomenon

    OpenAIRE

    Alina - Andreea CRUCERU

    2010-01-01

    On the basis of economic conditions being devalued in Romania, more and more persons were forced to find a work place – be it temporary or permanent – outside of the country’s borders. This phenomenon of international migration has, as a main effect, the emergence of a special category of persons, respectively that of children left behind under the care of one of the parents or of other people. The situation of these minors is extremely difficult because, lacking the careful supervision of th...

  8. Gravity as an emergent phenomenon: experimental signatures

    OpenAIRE

    Consoli, M.; Pluchino, A.

    2013-01-01

    According to some authors, gravity might be an emergent phenomenon in a fundamentally flat space-time. In this case the speed of light in the vacuum would not coincide exactly with the basic parameter "c" entering Lorentz transformations and, for an apparatus placed on the Earth's surface, light should exhibit a tiny fractional anisotropy at the level 10^{-15}. We argue that, most probably, this effect is now observed in many room-temperature ether-drift experiments and, in particular, in a v...

  9. Gauge fixing and the gibbs phenomenon

    International Nuclear Information System (INIS)

    We address the question of why global gauge fixing, specifically to the lattice Landau gauge, becomes an extremely lengthy process for large lattices. We construct an artificial 'gauge-fixing' problem which has the essential features encountered in actuality. In the limit in which the size of the system to be gauge fixed becomes infinite, the problem becomes equivalent to finding a series expansion in functions which are related to the Jacobi polynomials. The series converges slowly, as expected. It also converges non-uniformly, which is an observed characteristic of gauge fixing. In the limiting example, the non-uniformity arises through the Gibbs phenomenon

  10. CIRCULAR ECONOMY IN ROMANIA WITHIN EUROPEAN CONTEXT

    OpenAIRE

    Cornelia Marcela Danu; Valentin Nedeff

    2015-01-01

    In the present paper we have approached some conceptual and coordinated marks of the societal reality connected to the circular economy. Generated by „the limits of certainty” regarding the future of the world business, the operationalization of the circular economy has become a part of the EU strategies and started the various stages of implementation as an active process in all countries. We have highlighted the opportunities and the risks related to the circular economy, the European dimen...

  11. A COMPACT CIRCULARLY POLARIZED SLOTTED MICROSTRIP ANTENNA

    OpenAIRE

    V. Jebaraj; K.R.S. Ravi Kumar; D. Mohanageetha

    2014-01-01

    Slot antennas are often used at UHF and microwave frequencies. In slot antenna for RFID reader applications the frequency ranges from 902-923MHz to achieve circular polarization. The shapes and size of the slot, as well as the driving frequency, determine the radiation distribution pattern. The proposed compact size circularly polarized slotted microstrip antenna are summarized with design rules. The circularly polarized radiation in square patch antenna can be obtained by perturbation techni...

  12. Reconfigurable Monopole Antennas With Circular Polarization

    OpenAIRE

    Panahi, Afshin

    2015-01-01

    This thesis presents research on printed circularly-polarized monopole antennas and their application in reconfigurable monopole antennas. The proposed circularly-polarised monopole antennas benefit from advantages such as small size, low-cost, low-profile and simple designs. The first part of this thesis introduces three printed circularly-polarized monopole antennas for global navigation satellite systems and Wi-Fi applications. The primary focus is on the ground plane which is used as a ra...

  13. In-line phase retarder and polarimeter for conversion of linear to circular polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Smith, N.V.; Denlinger, J.D. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    An in-line polarimeter including phase retarder and linear polarizer was designed and commissioned on undulator beamline 7.0 for the purpose of converting linear to circular polarization for experiments downstream. In commissioning studies, Mo/Si multilayers at 95 eV were used both as the upstream, freestanding phase retarder and the downstream linear polarized. The polarization properties of the phase retarder were characterized by direct polarimetry and by collecting MCD spectra in photoemission from Gd and other magnetic surfaces. The resonant birefringence of transmission multilayers results from differing distributions of s- and p-component wave fields in the multilayer when operating near a structural (Bragg) interference condition. The resulting phase retardation is especially strong when the interference is at or near the Brewster angle, which is roughly 45{degrees} in the EUV and soft x-ray ranges.

  14. Molecular alignment using circularly polarized laser pulses

    CERN Document Server

    Smeenk, C T L

    2013-01-01

    We show that circularly polarized femtosecond laser pulses produce field-free alignment in linear and planar molecules. We study the rotational wavepacket evolution of O$_2$ and benzene created by circularly polarized light. For benzene, we align the molecular plane to the plane of polarization. For O$_2$, we demonstrate that circular polarization yields a net alignment along the laser propagation axis at certain phases of the evolution. Circular polarization gives us the ability to control alignment of linear molecules outside the plane of polarization, providing new capabilities for molecular imaging.

  15. The happy victimizer phenomenon: Not found here

    Directory of Open Access Journals (Sweden)

    Jevtić Ana

    2014-01-01

    Full Text Available Children’s attribution of emotions to a moral transgressor is an important research topic in the psychology of moral and emotional development. This is especially because of the so-called Happy Victimizer Phenomenon (HVP where younger children attribute positive emotions to a moral transgressor described in a story. In the two studies that we have conducted (children aged 5, 7 and 9, 20 of each age; 10 of each age in the second study we have tested the possible influence of the fear of sanctions and the type of transgression (stealing and inflicting body injuries on the attribution of emotions. Children were presented with stories that described transgressions and they were asked to answer how the transgressor felt. The fear of sanctions did not make a significant difference in attribution but the type of transgression did - more negative emotions were attributed for inflicting body injuries than for stealing. Positive emotions were explained with situational-instrumental explanations in 84% of cases while negative emotions were explained with moral explanations in 63,5%. Girls attributed more positive emotions (61% than boys (39%. However, our main finding was that, for the aforementioned age groups, we did not find the HVP effect although it has regularly been registered in foreign studies. This finding denies the generalizability of the phenomenon and points to the significance of disciplining styles and, even more so, culture for children’s attribution of emotions to moral transgressors.

  16. Turnpike phenomenon and infinite horizon optimal control

    CERN Document Server

    Zaslavski, Alexander J

    2014-01-01

    This book is devoted to the study of the turnpike phenomenon and describes the existence of solutions for a large variety of infinite horizon optimal control classes of problems.  Chapter 1 provides introductory material on turnpike properties. Chapter 2 studies the turnpike phenomenon for discrete-time optimal control problems. The turnpike properties of autonomous problems with extended-value intergrands are studied in Chapter 3. Chapter 4 focuses on large classes of infinite horizon optimal control problems without convexity (concavity) assumptions. In Chapter 5, the turnpike results for a class of dynamic discrete-time two-player zero-sum game are proven. This thorough exposition will be very useful  for mathematicians working in the fields of optimal control, the calculus of variations, applied functional analysis, and infinite horizon optimization. It may also be used as a primary text in a graduate course in optimal control or as supplementary text for a variety of courses in other disciplines. Resea...

  17. Circular polarization of light by planet Mercury and enantiomorphism of its surface minerals.

    Science.gov (United States)

    Meierhenrich, Uwe J; Thiemann, Wolfram H P; Barbier, Bernard; Brack, André; Alcaraz, Christian; Nahon, Laurent; Wolstencroft, Ray

    2002-04-01

    Different mechanisms for the generation of circular polarization by the surface of planets and satellites are described. The observed values for Venus, the Moon, Mars, and Jupiter obtained by photo-polarimetric measurements with Earth based telescopes, showed accordance with theory. However, for planet Mercury asymmetric parameters in the circular polarization were measured that do not fit with calculations. For BepiColombo, the ESA cornerstone mission 5 to Mercury, we propose to investigate this phenomenon using a concept which includes two instruments. The first instrument is a high-resolution optical polarimeter, capable to determine and map the circular polarization by remote scanning of Mercury's surface from the Mercury Planetary Orbiter MPO. The second instrument is an in situ sensor for the detection of the enantiomorphism of surface crystals and minerals, proposed to be included in the Mercury Lander MSE. PMID:12185675

  18. Numerical Study on Heat Transfer Deterioration of Supercritical n-Decane in Horizontal Circular Tubes

    OpenAIRE

    Yanhong Wang; Sufen Li; Ming Dong

    2014-01-01

    In order to obtain a deeper understanding of the regenerative cooling process of scramjet engines, in this paper, a numerical investigation on the supercritical convective heat transfer of n-decane in horizontal circular tubes was conducted, based on a complete set of conservation equations and the Renormalization group (RNG) k–ε turbulence model with enhanced wall treatment. The present study mainly focuses on the heat transfer deterioration (HTD) phenomenon, including the mechanism and c...

  19. La raó circular

    OpenAIRE

    Pinyol i Bori, Francesc

    2007-01-01

    És un text epistemològic sobre les qüestions cognitives circulars que apareixen: a) Quan el subjecte forma part de l'objecte estudiat; b) En la recerca de les bases del coneixement; c) Al voler justificar la inducció; d) En algunes interpretacions filosòfiques i científiques. S'hi explica l'estat del punt a) el més problemàtic, i s'aclareixen els altres tres punts: els b) i c) pel fet científic que l'evolució cognitiva humana ha anat acoblada a l'evolució biològica, la qual ha generat els a p...

  20. The United States pork niche market phenomenon.

    Science.gov (United States)

    Honeyman, M S; Pirog, R S; Huber, G H; Lammers, P J; Hermann, J R

    2006-08-01

    After the broad industrialization of the US pork industry, there has been a development of niche markets for export and domestic pork; that is, there is a pork niche market phenomenon. The US pork niche market phenomenon is characterized, and 2 of the major markets are explained in detail. With the Midwest's tradition of a diversified family-based agriculture and record low hog prices of the late 1990s, the conditions were conducive for this phenomenon to develop. Pork niche markets utilize various sales methods including Internet sales, local abattoir sales, direct marketing, farmer networks, and targeting to organized groups. In 2003, there were approximately 35 to 40 active pork niche marketing efforts in Iowa. The Berkshire breed is an example of a swine breed that has had a recent resurgence because of niche markets. Berkshire pork is known for tenderness and excellent quality. Berkshire registrations have increased 4-fold in the last 10 yr. One of the larger niche marketers of "natural pork" is Niman Ranch Pork, which has more than 400 farmer-producers and processes about 2,500 pigs weekly. Many US consumers of pork are interested in issues concerning the environment, food safety, pig welfare, and pig farm ownership and structure. These consumers may be willing to pay more for pork from farmers who are also concerned about these issues. Small- and medium-sized swine farmers are active in pork niche markets. Niche markets claim product differentiation by superior or unique product quality and social attributes. Quality attributes include certain swine breeds, and meat quality, freshness, taste or flavor, and tenderness. Social or credence attributes often are claimed and include freedom from antibiotics and growth promotants; local family farm production; natural, organic, outdoor, or bedded rearing; humane rearing; known origin; environmentally friendly production; and the absence of animal by-products in the feed. Niche pork markets and alternative swine

  1. [Electroencephalographic characteristics of the deja vu phenomenon].

    Science.gov (United States)

    Vlasov, P N; Cherviakov, A V; Gnezdinsiĭ, V V

    2013-01-01

    Déjà vu (DV, from French "already seen") is an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known. An aim of the study was to investigate EEG characteristics of DV in patients with epilepsy. We studied 166 people (63.2% women, mean age 25.17±9.19 years). The DV phenomenon was studied in patients (27 people) and in a control group (139 healthy people). Patients were interviewed for DV characteristics and underwent a long (12-16 h) ambulatory EEG-monitoring study. In EEG, DV episodes in patients began with polyspike activity in the right temporal lobe and, in some cases, ended with the slow-wave theta-delta activity in the right hemisphere. PMID:23739447

  2. Gravity as an emergent phenomenon: experimental signatures

    CERN Document Server

    Consoli, M

    2013-01-01

    According to some authors, gravity might be an emergent phenomenon in a fundamentally flat space-time. In this case the speed of light in the vacuum would not coincide exactly with the basic parameter "c" entering Lorentz transformations and, for an apparatus placed on the Earth's surface, light should exhibit a tiny fractional anisotropy at the level 10^{-15}. We argue that, most probably, this effect is now observed in many room-temperature ether-drift experiments and, in particular, in a very precise cryogenic experiment where this level of signal is about 100 times larger than the designed short-term stability. To fully appreciate what is going on, however, one should consider the vacuum as a true physical medium whose fundamental quantum nature gives rise to the irregular, non-deterministic pattern which characterizes the observed signal.

  3. PUBLIC RELATIONS AS AN INFORMATION PROCESS PHENOMENON

    Directory of Open Access Journals (Sweden)

    TKACH L. M.

    2016-06-01

    Full Text Available Formulation of the problem. If public relations as a phenomenon of information management are examined, we deal with the question of knowledge content and nature of relationship of PR with environment, ability to manage the perception and attitude of people to events in the environment; ensure priority of information over other resources. Goal. To investigate the concept of "public relations" of foreign and domestic experts; consider the typology of the public and the "laws" of public opinion; define the basic principles according to which relations with public should be built, and to identify PR activities as a kind of social communication. Conclusions. Public relations on the basis of advanced information and communication technologies create fundamentally new opportunities for information control and influence on public consciousness.

  4. Statistical analysis of the migration phenomenon

    Directory of Open Access Journals (Sweden)

    Alina - Andreea CRUCERU

    2010-11-01

    Full Text Available On the basis of economic conditions being devalued in Romania, more and more persons were forced to find a work place – be it temporary or permanent – outside of the country’s borders. This phenomenon of international migration has, as a main effect, the emergence of a special category of persons, respectively that of children left behind under the care of one of the parents or of other people. The situation of these minors is extremely difficult because, lacking the careful supervision of their evolution by their parents, they arefrequently confronted with problems of social adaptation, with learning difficulties and even with situations of willful breaking of legal norms.

  5. On the 'Meishan Phenomenon' in Song culture

    Institute of Scientific and Technical Information of China (English)

    Zhu Shangshu

    2006-01-01

    The Song Dynasty enjoyed a splendid culture.Meishan,a small county in Southwest Sichuan,was one of the most developed cultural areas.This is closely related to a large-scale immigration after the collapse of the an area receiving more immigrants than other regions.A great number of distinguished families from North China brought with them the advanced culture of the Yellow River areas to Meishan,which combined with native culture,and produced many"cultural clans"from this"clan culture."Some of these people became elites in various areas through education and the Civil Service Examinations.The so-called"Meishan Phenomenon"was a result of cultural melting.

  6. [Burnout: rising interest phenomenon in stressful workplace].

    Science.gov (United States)

    Della Valle, E; De Pascale, G; Cuccaro, A; Di Mare, M; Padovano, L; Carbone, U; Farinaro, E

    2006-01-01

    Many stressful situations, particularly strong and long time lasting, can induce the burnout syndrome. The definition "burnout" refers to emotional and exhausting conditions related to working environment. Since 70'ties, many studies, have focused on this topic, have assessed that this condition is much more frequent in some particular professional categories: teachers, physicians, nurses, social workers, policemen, judges (the so-called helping professions). The main syndrome characteristics are: physical and emotional fatigue, depersonalization, frustration for unsuccessful professional realization and reduced personal accomplishment in competence and productivity with decreasing critical sense towards working field. The Maslach Burnout Inventory (MBI) has been the most popular instrument for measuring burnout in medical research. The coherence of many studies results on helping professions in different countries, leads to the conclusion that basically burnout is a psycho-social phenomenon of international relevance. These studies have also identified personal, relational and environmental risk factors susceptible to prevention. PMID:16649514

  7. The Trump phenomenon, an explanation from sociophysics

    CERN Document Server

    Galam, Serge

    2016-01-01

    The Trump phenomenon is argued to depart from current populist rise in Europe. According to a model of opinion dynamics from sociophysics the machinery of Trump's amazing success obeys well-defined counter-intuitive rules. Therefore, his success was in principle predictable from the start. The model uses local majority rule arguments and obeys a threshold dynamics. The associated tipping points are found to depend on the leading collective beliefs, cognitive biases and prejudices of the social group which undertakes the public debate. And here comes the sesame of the Trump campaign, which develops along two successive steps. During a first moment, Trump's statement produces a majority of voters against him. But at the same time, according to the model the shocking character of the statement modifies the prejudice balance. In case the prejudice is present even being frozen among voters, the tipping point is lowered at Trump's benefit. Nevertheless, although the tipping point has been lowered by the activation ...

  8. Prussian phenomenon and its historical distortion

    Directory of Open Access Journals (Sweden)

    Oleg Y. Plenkov

    2016-03-01

    Full Text Available The article deals with the phenomenon of Prussia. Once, Prussia had been the largest continental Protestant state in Europe. The main issue of this phenomenon is that upon the tragic events of the World War II Prussian history and heritage had been considerably distorted, in order to compensate somehow for the dreadful casualties suffered by the victorious powers. The common European misconception implied that Prussia had been the bulwark of militarism, and therefore had to bear all the responsibility for the atrocities of war. Unfortunately, the majority of modern German historians share such misinterpretation of Prussian heritage in order to please false political correctness, perhaps, as an act of contrition for National Socialism and its crimes. However, the Prussian tradition and history go far beyond this militarism, and this article explains what ways. The authors believe that there should not be any prejudices and biases, that any subject should be examined sine ira et studio. Moreover, given that it is possible to characterize the Great French Revolution as a juristic one, and the Great October revolution – as a social one, the Prussian revolution “from above”, led by the first representatives of the Hohenzollern family, may be well considered as a pedagogical revolution. This revolution did bring definitely positive changes; they are surveyed in the article. The French Revolution has not eliminated the covetousness of the bourgeoisie after 1789; despotism of the authorities and people’s passiveness similarly have remained unaltered in Russia after 1917. On the contrary, Federal Republic of Germany of nowadays, distinctive for its law, order and effective responsible government is unthinkable without Prussian heritage.

  9. Generation of OAM Radio Waves Using Circular Vivaldi Antenna Array

    Directory of Open Access Journals (Sweden)

    Changjiang Deng

    2013-01-01

    Full Text Available This paper gives a feasible and simple solution of generating OAM-carrying radio beams. Eight Vivaldi antenna elements connect sequentially and fold into a hollow cylinder. The circular Vivaldi antenna array is fed with unit amplitude but with a successive phase difference from element to element. By changing the phase difference at the steps of 0, ±45°, ±90°, ±135°, and 180°, the OAM radio beam can be generated with mode numbers 0, ±1, ±2, ±3, and 4. Simulations show that the OAM states of ±2 and ±3 are the same as the traditional states, while the OAM states of 0, ±1, and 4 differ at the boresight. This phenomenon can be explained by the radiation pattern difference between Vivaldi antenna and tripole antenna. A solution of distinguishing OAM states is also proposed. The mode number of OAM can be distinguished with only 2 receivers.

  10. Microstrip Antenna Generates Circularly Polarized Beam

    Science.gov (United States)

    Huang, J.

    1986-01-01

    Circular microstrip antenna excited with higher order transverse magnetic (TM) modes generates circularly polarized, conical radiation patterns. Found both theoretically and experimentally that peak direction of radiation pattern is varied within wide angular range by combination of mode selection and loading substrate with materials of different dielectric constants.

  11. Circular Loudspeaker Array with Controllable Directivity

    DEFF Research Database (Denmark)

    Møller, Martin; Olsen, Martin; Agerkvist, Finn T.;

    2010-01-01

    Specific directivity patterns for circular arrays of loudspeakers can be achieved by utilizing the concept of phase-modes, which expands the directivity pattern into a series of circular harmonics. This paper investigates the applicability of this concept applied on a loudspeaker array on a...

  12. Underwater Acoustic Sensors Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Giuseppe Parente

    2009-06-01

    Full Text Available We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, showing that the sensitivity is not influenced by the shape but by the transversal dimension and the material characteristics of the coating.

  13. Application of the Transmission Bragg Gratings for Vibration Monitoring

    CERN Document Server

    Tikhonov, E A

    2010-01-01

    It is shown that the optical-electronic system consisted of the transmission Bragg grating, a laser and the intermediate sensitive to the vibrations mirror can detect the vibrations, when touched by them laser beam scan will exceed the angular divergence of the beam. The mathematical model of the sensor of the vibrations presented in the form of Taylor series describes the system response taking into account the operating point, in particular, describes the effect of the doubling of the modulation frequency response relative to the frequency of acting vibrations.

  14. On-Chip Silicon Waveguide Bragg Grating Photonic Temperature Sensor

    CERN Document Server

    Klimov, Nikolai N; Berger, Michaela; Ahmed, Zeeshan

    2015-01-01

    Resistance thermometry is a time-tested method for taking temperature measurements. In recent years fundamental limits to resistance-based approaches spurred considerable interest in developing photonic temperature sensors as a viable alternative. In this study we demonstrate that our photonic thermometer, which consists of a silicon waveguide integrated with a Bragg grating, can be used to measure temperature changes over the range from 5 C to 160 C with a combined expanded uncertainty [k = 2 ; 95% confidence level] of 1.25 degree C. The computational modeling of the sensor predicts the resonance wavelength and effective refractive index within 4% of the measured value.

  15. Photoluminescence and X-ray Diffraction of Distributed Bragg Reflector

    Institute of Scientific and Technical Information of China (English)

    LI Lin; LI Yong-da; LIU Wen-li; LU Bin; JU Guo-xian; ZHANG Yong-ming; HAO Yong-qin; SU Wei; ZHONG Jing-chang

    2004-01-01

    Spectral and structural characteristics of distributed Bragg reflector (DBR) in vertical-cavity surface-emitting lasers were studied with photoluminescence and double- crystal X- ray diffraction measurement. The expected high quality epitaxial DBR structure was verified. In the X- ray double- crystal rocking curves of DBR the zeroth- order peak, the first and second order satellite peaks were measured.Splitting of diffraction peak appeared in the rocking curves was analyzed. The effects of introduced deep energy levels on the structural perfection and optical properties were discussed.

  16. Reannealed Fiber Bragg Gratings Demonstrated High Repeatability in Temperature Measurements

    Science.gov (United States)

    Adamovsky, Grigory; Juergens, Jeffrey R.

    2004-01-01

    Fiber Bragg gratings (FBGs) are formed by periodic variations of the refractive index of an optical fiber. These periodic variations allow an FBG to act as an embedded optical filter, passing the majority of light propagating through a fiber while reflecting back a narrow band of the incident light. The peak reflected wavelength of the FBG is known as the Bragg wavelength. Since the period and width of the refractive index variation in the fiber determines the wavelengths that are transmitted and reflected by the grating, any force acting on the fiber that alters the physical structure of the grating will change the wavelengths that are transmitted and reflected by it. Both thermal and mechanical forces acting on the grating will alter its physical characteristics, allowing the FBG sensor to detect both the temperature variations and the physical stresses and strains placed upon it. This ability to sense multiple physical forces makes the FBG a versatile sensor. To assess the feasibility of using Bragg gratings as temperature sensors for propulsion applications, researchers at the NASA Glenn Research Center evaluated the performance of Bragg gratings at elevated temperatures for up to 300 C. For these purposes, commercially available polyimide-coated high-temperature gratings were used that were annealed by the manufacturer to 300 C. To assure the most thermally stable gratings at the operating temperatures, we reannealed the gratings to 400 C at a very slow rate for 12 to 24 hr until their reflected optical powers were stabilized. The reannealed gratings were then subjected to periodic thermal cycling from room temperature to 300 C, and their peak reflected wavelengths were monitored. The setup shown is used for reannealing and thermal cycling the FBGs. Signals from the photodetectors and the spectrum analyzer were fed into a computer equipped with LabVIEW software. The software synchronously monitored the oven/furnace temperature and the optical spectrum analyzer

  17. OPTIMIZATION OF INTRAGRATING SENSING USING FIBER BRAGG GRATING

    OpenAIRE

    B.B.PADHY; HAFTAY ABADI GEBRU; SANDIPAN M.NALAWADE

    2011-01-01

    Linearly Chirped Fiber Bragg Gratings (FBGs) have been optimized and investigated for intragrating sensing. The side lobes have been suppressed using Gaussian apodization while maintaining the peak reflectivity and the bandwidth of the reflected signal. We have achieved a chirp rate of 0.5 to 2 nm/mm for intragrating sensing.Average thermal sensitivity of 11.55 pm/ oC is obtained which is higher than uniform FBGs. We have achieved novel characteristics of linearly chirped FBGs under the effec...

  18. OPTIMIZATION OF INTRAGRATING SENSING USING FIBER BRAGG GRATING

    Directory of Open Access Journals (Sweden)

    B.B.PADHY

    2011-01-01

    Full Text Available Linearly Chirped Fiber Bragg Gratings (FBGs have been optimized and investigated for intragrating sensing. The side lobes have been suppressed using Gaussian apodization while maintaining the peak reflectivity and the bandwidth of the reflected signal. We have achieved a chirp rate of 0.5 to 2 nm/mm for intragrating sensing.Average thermal sensitivity of 11.55 pm/ oC is obtained which is higher than uniform FBGs. We have achieved novel characteristics of linearly chirped FBGs under the effect of non-monotonic physical parameter distribution fields for excellent spectral response profile for intragrating sensing.

  19. Microfiber-Based Bragg Gratings for Sensing Applications: A Review

    Directory of Open Access Journals (Sweden)

    Jun-Long Kou

    2012-06-01

    Full Text Available Microfiber-based Bragg gratings (MFBGs are an emerging concept in ultra-small optical fiber sensors. They have attracted great attention among researchers in the fiber sensing area because of their large evanescent field and compactness. In this review, the basic techniques for the fabrication of MFBGs are introduced first. Then, the sensing properties and applications of MFBGs are discussed, including measurement of refractive index (RI, temperature, and strain/force. Finally a summary of selected MFBG sensing elements from previous literature are tabulated.

  20. Passive Temperature-Compensating Technique for Microstructured Fiber Bragg Gratings

    CERN Document Server

    Huy, Minh Châu Phan; Dewynter, Véronique; Ferdinand, Pierre; Pagnoux, Dominique; Dussardier, Bernard; Blanc, Wilfried; 10.1109/JSEN.2008.926169

    2010-01-01

    The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For instance, the spectral range of variations is divided by a factor of 4 over a temperature range larger than 20\\degree C in a six-hole MOF, and the maximum sensitivity is reduced. Such passive FBG temperature compensation technique is of great interest for applications involving accurate sensing free of thermal effects.

  1. Dynamic gate algorithm for multimode fiber Bragg grating sensor systems.

    Science.gov (United States)

    Ganziy, D; Jespersen, O; Woyessa, G; Rose, B; Bang, O

    2015-06-20

    We propose a novel dynamic gate algorithm (DGA) for precise and accurate peak detection. The algorithm uses a threshold-determined detection window and center of gravity algorithm with bias compensation. We analyze the wavelength fit resolution of the DGA for different values of the signal-to-noise ratio and different peak shapes. Our simulations and experiments demonstrate that the DGA method is fast and robust with better stability and accuracy than conventional algorithms. This makes it very attractive for future implementation in sensing systems, especially based on multimode fiber Bragg gratings. PMID:26193010

  2. Underwater acoustic sensors based on fiber bragg gratings.

    Science.gov (United States)

    Campopiano, Stefania; Cutolo, Antonello; Cusano, Andrea; Giordano, Michele; Parente, Giuseppe; Lanza, Giuseppe; Laudati, Armando

    2009-01-01

    We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating) under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, showing that the sensitivity is not influenced by the shape but by the transversal dimension and the material characteristics of the coating. PMID:22408534

  3. A porous silicon Bragg grating waveguide by direct laser writing

    Energy Technology Data Exchange (ETDEWEB)

    Rea, Ilaria; Iodice, Mario; Coppola, Giuseppe; Rendina, Ivo; De Stefano, Luca [National Council of Research, Institute for Microelectronic and Microsystems, Department of Naples, Via P Castellino 111, I-80131 Naples (Italy); Marino, Antigone [Department of Physics, ' Federico II' University of Naples, Via Cinthia, I-80126 Naples (Italy)], E-mail: ilaria.rea@na.imm.cnr.it

    2008-09-10

    We have designed, fabricated and characterized a porous silicon-based Bragg grating integrated in an optical waveguide, by using a low cost and fast technique, direct laser writing. A periodic optical structure with a pitch of 10 {mu}m, resonant in the near-infrared wavelength region, has been obtained. The simulated transmission spectra, calculated by the transfer matrix method and waveguide modal computation, are in good qualitative agreement with the experimental ones. The waveguide transmission losses have been quantified as 22 dB cm{sup -1}.

  4. A porous silicon Bragg grating waveguide by direct laser writing

    International Nuclear Information System (INIS)

    We have designed, fabricated and characterized a porous silicon-based Bragg grating integrated in an optical waveguide, by using a low cost and fast technique, direct laser writing. A periodic optical structure with a pitch of 10 μm, resonant in the near-infrared wavelength region, has been obtained. The simulated transmission spectra, calculated by the transfer matrix method and waveguide modal computation, are in good qualitative agreement with the experimental ones. The waveguide transmission losses have been quantified as 22 dB cm-1

  5. Ultrafast laser inscribed fiber Bragg gratings for sensing applications

    Science.gov (United States)

    Mihailov, Stephen J.

    2016-05-01

    Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on femtosecond infrared laser-material processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This tutorial paper will present a review of some of the more recent developments.

  6. Fiber-bragg grating-loop ringdown method and apparatus

    Science.gov (United States)

    Wang, Chuji

    2008-01-29

    A device comprising a fiber grating loop ringdown (FGLRD) system of analysis is disclosed. A fiber Bragg grating (FBG) or Long-Period grating (LPG) written in a section of single mode fused silica fiber is incorporated into a fiber loop. By utilizing the wing areas of the gratings' bandwidth as a wavelength dependent attenuator of the light transmission, a fiber grating loop ringdown concept is formed. One aspect of the present invention is temperature sensing, which has been demonstrated using the disclosed device. Temperature measurements in the areas of accuracy, stability, high temperature, and dynamic range are also described.

  7. CIRCULAR ECONOMY IN ROMANIA WITHIN EUROPEAN CONTEXT

    Directory of Open Access Journals (Sweden)

    Cornelia Marcela Danu

    2015-07-01

    Full Text Available In the present paper we have approached some conceptual and coordinated marks of the societal reality connected to the circular economy. Generated by „the limits of certainty” regarding the future of the world business, the operationalization of the circular economy has become a part of the EU strategies and started the various stages of implementation as an active process in all countries. We have highlighted the opportunities and the risks related to the circular economy, the European dimension and, in particular, the Romanian one of this process, the role of the triad: consumer-company-natural environment, while implementing the circular economy. Circular economy is both a new approach of the societal life, based on changing the mentalities of the individuals having the role of decision makers at the company level and public administration and the decision makers – consumers, as well as a policy meant to be made operational across all entities: governmental, entrepreneurial, individually – human.

  8. Gauge-Invariant Formulation of Circular Dichroism.

    Science.gov (United States)

    Raimbault, Nathaniel; de Boeij, Paul L; Romaniello, Pina; Berger, J A

    2016-07-12

    Standard formulations of magnetic response properties, such as circular dichroism spectra, are plagued by gauge dependencies, which can lead to unphysical results. In this work, we present a general gauge-invariant and numerically efficient approach for the calculation of circular dichroism spectra from the current density. First we show that in this formulation the optical rotation tensor, the response function from which circular dichroism spectra can be obtained, is independent of the origin of the coordinate system. We then demonstrate that its trace is independent of the gauge origin of the vector potential. We also show how gauge invariance can be retained in practical calculations with finite basis sets. As an example, we explain how our method can be applied to time-dependent current-density-functional theory. Finally, we report gauge-invariant circular dichroism spectra obtained using the adiabatic local-density approximation. The circular dichroism spectra we thus obtain are in good agreement with experiment. PMID:27295541

  9. Nanofocusing in circular sector-like nanoantennas

    DEFF Research Database (Denmark)

    Zenin, Volodymyr; Pors, Anders Lambertus; Han, Zhanghua;

    2014-01-01

    Gold circular sector-like nanoantennas (with a radius of 500 nm and a taper angle of 60°, 90°, and 120°) on glass are investigated in a near-infrared wavelength range (900 - 2100 nm). Amplitude- and phase-resolved near-field images of circular sector-like antenna modes at telecom wavelength feature...... a concentric circular line of phase contrast, demonstrating resonant excitation of a standing wave of counter-propagating surface plasmons, travelling between a tip and opposite circular edge of the antenna. Transmission spectra obtained in the range 900 - 2100 nm are in good agreement with...... makes circular sector-like nanoantennas very promising for implementing bowtie antennas and attractive for many applications....

  10. Optical Properties of High Sensitivity Fiber Bragg Grating on Temperature Sensor

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the spectrum shift properties of the center reflection wavelength detected to be based on the FBG sensor with ambient temperature change. The basic theoretical methods and numerical simulation for the spectral properties of uniform Bragg grating is analyzed by using coupling mode theory which is optical properties of high sensitivity fiber Bragg grating on temperature sensor in accordance with experiment.

  11. Numerical Simulation of Bragg Reflection Based on Linear Waves Propagation over A Series of Rectangular Seabed

    Institute of Scientific and Technical Information of China (English)

    Chih-Chung WEN; Li-Hung TSAI

    2008-01-01

    A numerical model, Evolution Equation of Mild-Slope Equation (EEMSE) developed by Hsu et al. (2003), was applied to study the Bragg reflection of water waves over a series of rectangular seabed. Three key parameters of the Bragg reflection including the peak coefficient of primary Bragg reflection, its corresponding relative wavelength, and the bandwidth, have shown to be effective in describing the characteristics of the primary Bragg reflection. The characteristics of the Bragg reflection were investigated under the various conditions comprising number, height, and spacing interval of a series of rectangular seabed. The results reveal that the peak of Bragg reflection increases with the increase of rectangular seabed height and number, the bandwidth and the shift value of the Bragg reflection depend on the increase of the rectangular seabed height as well as the decrease of rectangular seabed number, and the relative rectangular seabed spacing in the rang of 3 and 4 could produce higher Bragg reflection. Finally, a correlative and regressive analysis is performed by use of the calculated data. Based on the results of the analysis, empirical equations were established. Our study results can provide an appropriate choice of a series of rectangular seabed field for a practical design.

  12. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    OpenAIRE

    Zheng WenJun; Fei GuangTao; Wang Biao; Zhang Li

    2009-01-01

    Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR) using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  13. Modulation of Transmission Spectra of Anodized Alumina Membrane Distributed Bragg Reflector by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Zheng WenJun

    2009-01-01

    Full Text Available Abstract We have successfully prepared anodized alumina membrane distributed Bragg reflector (DBR using electrochemical anodization method. The transmission peak of this distributed Bragg reflector could be easily and effectively modulated to cover almost any wavelength range of the whole visible spectrum by adjusting anodization temperature.

  14. Fabrication of the Long Bragg Grating by Excimer Laser Micro Machining with High-Precision Positioning XXY Platform

    OpenAIRE

    Jian-Zhong Wu; Jian-Cin Chao; Jui-Yi Hu; Chia-Chin Chiang

    2014-01-01

    With the advancement of technology, the application of fiber Bragg grating is widely used as a Bragg grating sensor. Fiber Bragg grating is fabrication using excimer laser machining with the phase masker. The grating length is decided by the width of laser beam. In this paper, we proposed fabrication of the long Bragg grating by excimer Laser micro machining with a high-precision positioning XXY platform. The high-precision positioning XXY platform plays an important role for long FBG. It nee...

  15. Calculated x-ray dichroic signals and resonant Bragg diffraction structure factors for dysprosium borocarbide (DyB2C2)

    International Nuclear Information System (INIS)

    Low temperature properties of dysprosium borocarbide display evidence of two continuous phase transitions; it has been proposed that the first involves ordering of Dy quadrupole moments and, at a lower temperature, the second involves ordering of Dy magnetic moments. The latter has been established by magnetic neutron diffraction. Insight to the first phase transition, at TQ, has been sought by resonant x-ray Bragg diffraction, which reveals charge-forbidden (Templeton-Templeton) intensities (00l + 1/2) that increase continuously with decreasing temperature. We show that this scattering is absent if the space group is P4/mbm which has been proposed for the high temperature crystal structure. Tanaka et al. (1999) report evidence that at TQ the lattice distorts and the new space group is P42/mnm. The lower point-group symmetry of Dy ions in this space group is shown by us to allow diffraction at (00l + 1/2) and, indeed, in part it is due to Dy quadrupole moments. In the magnetically ordered phase two neighbouring Dy moments along the c-axis are mutually perpendicular and two neighbouring moments in the plane normal to the c-axis are almost oppositely aligned. This magnetic configuration and point-group symmetry 2/m for Dy sites lead us to predict magnetic and charge scattering at reflections (00l + 1/2) in the magnetically ordered phase. At reflections (h0l) and h odd calculated structure factors are purely magnetic. Our finding is consistent with data collected by Hirota et al. (2000) at the reflection (102). We report expressions for circular and linear dichroic signals and structure factors for Bragg scattering for the interpretation of future experiments. The structure factors are appropriate for azimuthal-angle scans in which the crystal is rotated about the (00l + 1/2) or the (h0l) Bragg wavevectors. (author)

  16. UV inactivation of enzymes in supramolecular complexes of biological membranes. The phenomenon of photochemical allotropy

    International Nuclear Information System (INIS)

    The photosensitivity of erythrocyte acetylcholinesterase (AChE) is different in its free and membrane-bound states. The modification of the structure of membraneous lipids by phospholipases A2, C and D or by cholesterol depletion is accompanied by a change in AChE photosensitivity. UV light was demonstrated to induce cooperative structural transitions in the erythrocyte membrane. This follows from the data obtained by circular dichroism and solubilization in detergents. In contrast to free AChE, UV light acts on the membraneous enzyme as a mixed inhibitor (simultaneous change in Vsub(max) and Ksub(m)). The anomalous behaviour of membrane-bound enzyme, termed the phenomenon of photochemical allotropy, is associated with a modification of the structure within the microenvironment of the residual AChE. The phenomenon depends on membrane integrity, and disappears after treatment of erythrocyte ghosts with ultrasound, trypsin, phospholipases and neuraminidase and remains unchanged in cholesterol-depleted membranes. The nature and localization of events responsible for this phenomenon are discussed. (author)

  17. Muscular condition monitoring system using fiber bragg grating sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Young; Lee, Jin Hyuk; Kim, Dae Hyun [Seoul National University of Technology, Seoul (Korea, Republic of)

    2014-10-15

    Fiber optic sensors (FOS) have advantages such as electromagnetic interference (EMI) immunity, corrosion resistance and multiplexing capability. For these reasons, they are widely used in various condition monitoring systems (CMS). This study investigated a muscular condition monitoring system using fiber optic sensors (FOS). Generally, sensors for monitoring the condition of the human body are based on electro-magnetic devices. However, such an electrical system has several weaknesses, including the potential for electro-magnetic interference and distortion. Fiber Bragg grating (FBG) sensors overcome these weaknesses, along with simplifying the devices and increasing user convenience. To measure the level of muscle contraction and relaxation, which indicates the muscle condition, a belt-shaped FBG sensor module that makes it possible to monitor the movement of muscles in the radial and circumferential directions was fabricated in this study. In addition, a uniaxial tensile test was carried out in order to evaluate the applicability of this FBG sensor module. Based on the experimental results, a relationship was observed between the tensile stress and Bragg wavelength of the FBG sensors, which revealed the possibility of fabricating a muscular condition monitoring system based on FBG sensors.

  18. A simple Bragg detector design for AMS and IBA applications

    Science.gov (United States)

    Müller, Arnold Milenko; Döbeli, Max; Seiler, Martin; Synal, Hans-Arno

    2015-08-01

    A new compact Bragg type gas ionization chamber (GIC) has been built for use as particle counter in AMS and IBA applications. The detector stands out due to its simple concept, which does not include a Frisch grid. Test experiments have been performed with ions in the mass range from He to Th and energies ranging from 30 keV to 2.5 MeV, in order to find optimal measurement conditions and to characterize the detector performance. For projectiles heavier than Al at energies below 2.5 MeV the obtained energy resolution is comparable with that of a state-of-the-art GIC with Frisch grid and clearly outperforms solid state detectors. Additionally the operation of this simplified Bragg GIC in the electron multiplication mode was investigated for the first time, which allows the detection of radiocarbon ions at energies below 50 keV with an energy resolution of the order of 10 keV.

  19. Muscular condition monitoring system using fiber bragg grating sensors

    International Nuclear Information System (INIS)

    Fiber optic sensors (FOS) have advantages such as electromagnetic interference (EMI) immunity, corrosion resistance and multiplexing capability. For these reasons, they are widely used in various condition monitoring systems (CMS). This study investigated a muscular condition monitoring system using fiber optic sensors (FOS). Generally, sensors for monitoring the condition of the human body are based on electro-magnetic devices. However, such an electrical system has several weaknesses, including the potential for electro-magnetic interference and distortion. Fiber Bragg grating (FBG) sensors overcome these weaknesses, along with simplifying the devices and increasing user convenience. To measure the level of muscle contraction and relaxation, which indicates the muscle condition, a belt-shaped FBG sensor module that makes it possible to monitor the movement of muscles in the radial and circumferential directions was fabricated in this study. In addition, a uniaxial tensile test was carried out in order to evaluate the applicability of this FBG sensor module. Based on the experimental results, a relationship was observed between the tensile stress and Bragg wavelength of the FBG sensors, which revealed the possibility of fabricating a muscular condition monitoring system based on FBG sensors.

  20. Multilayer Bragg Fresnel zone plate for coherent HHG radiation

    International Nuclear Information System (INIS)

    Coherent diffractive imaging in the (soft) X-ray regime is an emerging new lens-less X-ray microscopy technique with the future potential of molecular or even atomic resolution, because it is ultimately limited by the wavelength of the illuminating radiation and not by the imaging quality of the X-ray lens. However, this technique depends on the availability of coherent x-ray sources as well as optics for spectral filtering and focusing. We describe the development fabrication and testing of a reflective multilayer Bragg Fresnel phase zone plate for focusing coherent XUV radiation at 13 nm wavelength from a High Harmonic Generation source. This X-ray optical device serves for spectral filtering as well as sub-micron focusing of the HH spectrum in a single element for largely reduced losses. Large zone plate structures (conventional, spiral) matching the HH beam size are recorded by e-beam lithography in ultrathin HSQ e-beam resist and over-coated with a reflective Mo/Si multilayer by ion beam deposition. By accurately matching the groove depth of the diffractive structure to odd multiples of the quarter Bragg wavelength, the total diffraction efficiency can be improved by a factor of 4 theoretically compared to amplitude structures.

  1. Self-consistent electrodynamic scattering in the symmetric Bragg case

    International Nuclear Information System (INIS)

    We have analyzed the symmetric Bragg case, introducing a model of self consistent scattering for two elliptically polarized beams. The crystal is taken as a set of mathematical planes, each of them defined by a surface density of dipoles. We have considered the mesofield and the epifield differently from that of the Ewald's theory and, we assumed a plane of dipoles and the associated fields as a self consistent scattering unit. The exact analytical treatment when applied to any two neighbouring planes, results in a general and self consistent Bragg's equation, in terms of the amplitude and phase variations. The generalized solution for the set of N planes was obtained after introducing an absorption factor in the incident radiation, in two ways: (i) the analytical one, through a rule of field similarity, which says that the incidence occurs in both faces of the all crystal planes and also, through a matricial development with the Chebyshev polynomials; (ii) using the numerical solution we calculated, iteratively, the reflectivity, the reflection phase, the transmissivity, the transmission phase and the energy. The results are showed through reflection and transmission curves, which are characteristics as from kinematical as dynamical theories. The conservation of the energy results from the Ewald's self consistency principle is used. In the absorption case, the results show that it is not the only cause for the asymmetric form in the reflection curves. The model contains basic elements for a unified, microscope, self consistent, vectorial and exact formulation for interpretating the X ray diffraction in perfect crystals. (author)

  2. Self-heated fiber Bragg grating sensors for cryogenic environments

    Science.gov (United States)

    Chen, Tong; Swinehart, Philip R.; Maklad, Mokhtar S.; Buric, Michael P.; Chen, Kevin P.

    2010-04-01

    Cryogenic fuels are often considered as major energy alternatives to coal and petroleum based fuels. Safe and reliable sensor networks are required for on-demand, real-time fuel management in cryogenic environments. In this paper, a new sensor design is described that enhances the low-temperature performance of fiber sensors. FBGs inscribed in high attenuation fiber (HAF) are used to absorb in-fiber power light to raise the local sensor temperature in the cryogenic environment. When in-fiber power light is turned off, FBG sensors can serve as passive sensors to gauge temperature and stress in the cryogenic system. When the in-fiber power light is turned on, the heated sensors can be used to rapidly gauge fuel level and fuel leaks. In one example, a hydrogen gas sensor is demonstrated with a palladium-coated fiber Bragg grating (FBG). The low-temperature performance of the sensor was improved by heating the gratings as much as 200 K above the ambient temperature, and hydrogen concentration well below the 4% explosion limit was measured at 123K. In a second example, an array of four aluminum coated fiber Bragg gratings was used to measure liquid level in a cryogenic environment.

  3. A simple Bragg detector design for AMS and IBA applications

    International Nuclear Information System (INIS)

    A new compact Bragg type gas ionization chamber (GIC) has been built for use as particle counter in AMS and IBA applications. The detector stands out due to its simple concept, which does not include a Frisch grid. Test experiments have been performed with ions in the mass range from He to Th and energies ranging from 30 keV to 2.5 MeV, in order to find optimal measurement conditions and to characterize the detector performance. For projectiles heavier than Al at energies below 2.5 MeV the obtained energy resolution is comparable with that of a state-of-the-art GIC with Frisch grid and clearly outperforms solid state detectors. Additionally the operation of this simplified Bragg GIC in the electron multiplication mode was investigated for the first time, which allows the detection of radiocarbon ions at energies below 50 keV with an energy resolution of the order of 10 keV

  4. Transient alien limb phenomenon in right frontoparietal infarction

    OpenAIRE

    Panda Samhita

    2010-01-01

    Alien limb phenomenon is associated with different neurological disorders, such as stroke and corticobasal degeneration. It is usually caused by involvement of the corpus callosum, with or without the frontal regions. Rarely, it can result from insult in the posterior cerebral artery territory. Alien limb phenomenon is generally persistent. Here, an unusual case of transient alien hand phenomenon is reported.

  5. Transient alien limb phenomenon in right frontoparietal infarction

    Directory of Open Access Journals (Sweden)

    Panda Samhita

    2010-01-01

    Full Text Available Alien limb phenomenon is associated with different neurological disorders, such as stroke and corticobasal degeneration. It is usually caused by involvement of the corpus callosum, with or without the frontal regions. Rarely, it can result from insult in the posterior cerebral artery territory. Alien limb phenomenon is generally persistent. Here, an unusual case of transient alien hand phenomenon is reported.

  6. Vacuum phenomenon in the metatarsophalangeal joint of a horse

    International Nuclear Information System (INIS)

    Vacuum phenomenon was induced inadvertently during radiographic examination of a metatarsophalangeal joint of a lame horse. The phenomenon was recreated in a sound horse when a metacarpophalangeal joint was radiographed in a stress-flexed position. Distraction of apposing articular surfaces may induce the vacuum phenomenon, which could result in misdiagnosis of an osteochondral defect or fracture

  7. Anesthesia cutoff phenomenon: Interfacial hydrogen bonding

    International Nuclear Information System (INIS)

    Anesthesia cutoff refers to the phenomenon of loss of anesthetic potency in a homologous series of alkanes and their derivatives when their sizes become too large. In this study, hydrogen bonding of 1-alkanol series (ethanol to eicosanol) to dipalmitoyl-L-alpha-phosphatidylcholine (DPPC) was studied by Fourier transform infrared spectroscopy (FTIR) in DPPC-D2O-in-CCl4 reversed micelles. The alkanols formed hydrogen bonds with the phosphate moiety of DPPC and released the DPPC-bound deuterated water, evidenced by increases in the bound O-H stretching signal of the alkanol-DPPC complex and also in the free O-D stretching band of unbound D2O. These effects increased according to the elongation of the carbon chain of 1-alkanols from ethanol (C2) to 1-decanol (C10), but suddenly almost disappeared at 1-tetradecanol (C14). Anesthetic potencies of these alkanols, estimated by the activity of brine shrimps, were linearly related to hydrogen bond-breaking activities below C10 and agreed with the FTIR data in the cutoff at C10

  8. Evolution as a molecular cooperative phenomenon

    International Nuclear Information System (INIS)

    We discuss an hypothesis according to which microscopic mechanisms due to cooperation, at the molecular level, may have been key factors in the evolution of life on Earth. We view our hypothesis as a natural extension to the molecular level of viewing cooperation (symbiosis) as an evolutionary driving force; this does not restrict the interpretation of the evolutionary process to be the result of slow accumulation of mutations in the DNA. Some evidence supporting this hypothesis is discussed: (a) The Salam enhancement factor. This molecular phenomenon was recently introduced in order to understand the bases of the first unifying principle of biochemistry, namely that transcription of all known genes in prokaryotes, protists, metazoan, and metaphytes are translated into L-amino acids, except for some bacterial membrane proteins. (b) The role that cooperative phenomena may have played in the origin of evolution itself, i.e., in the resolution of Sagan's ultraviolet paradox. (c) The relationship between evolution and the constraints imposed by embryonic development. This is considered from the point of view of molecular cooperative phenomena. (author). Refs

  9. Priming intelligent behavior: an elusive phenomenon.

    Directory of Open Access Journals (Sweden)

    David R Shanks

    Full Text Available Can behavior be unconsciously primed via the activation of attitudes, stereotypes, or other concepts? A number of studies have suggested that such priming effects can occur, and a prominent illustration is the claim that individuals' accuracy in answering general knowledge questions can be influenced by activating intelligence-related concepts such as professor or soccer hooligan. In 9 experiments with 475 participants we employed the procedures used in these studies, as well as a number of variants of those procedures, in an attempt to obtain this intelligence priming effect. None of the experiments obtained the effect, although financial incentives did boost performance. A Bayesian analysis reveals considerable evidential support for the null hypothesis. The results conform to the pattern typically obtained in word priming experiments in which priming is very narrow in its generalization and unconscious (subliminal influences, if they occur at all, are extremely short-lived. We encourage others to explore the circumstances in which this phenomenon might be obtained.

  10. Interhemispheric sensorimotor integration; an upper limb phenomenon?

    Science.gov (United States)

    Ruddy, Kathy L; Jaspers, Ellen; Keller, Martin; Wenderoth, Nicole

    2016-10-01

    Somatosensory information from the limbs reaches the contralateral Primary Sensory Cortex (S1) with a delay of 23ms for finger, and 40ms for leg (somatosensory N20/N40). Upon arrival of this input in the cortex, motor evoked potentials (MEPs) elicited by Transcranial Magnetic Stimulation (TMS) are momentarily inhibited. This phenomenon is called 'short latency afferent inhibition (SAI)' and can be used as a tool for investigating sensorimotor interactions in the brain. We used SAI to investigate the process of sensorimotor integration in the hemisphere ipsilateral to the stimulated limb. We hypothesized that ipsilateral SAI would occur with a delay following the onset of contralateral SAI, to allow for transcallosal conduction of the signal. We electrically stimulated the limb either contralateral or ipsilateral to the hemisphere receiving TMS, using a range of different interstimulus intervals (ISI). We tested the First Dorsal Interosseous (FDI) muscle in the hand, and Tibialis Anterior (TA) in the lower leg, in three separate experiments. Ipsilateral SAI was elicited in the upper limb (FDI) at all ISIs that were greater than N20+18ms (all pintegration. PMID:27425210

  11. Empirical Study on the Creative Accounting Phenomenon

    Directory of Open Access Journals (Sweden)

    Cernusca Lucian

    2016-06-01

    Full Text Available The present study aims to analyze the accounting professionals’ point of view as opposed to the students and master students’ one, regarding the creative accounting phenomenon existence and manifestation forms. In order to accomplish this objective, there has been used the poll/investigation, as a research method and the questionnaire, as a research instrument. Within the study, there is suggested the testing of more hypotheses that contribute to the clarifying of the aspects wished to be analyzed through the research. These hypotheses’ acceptance or rejection is based on the „chi-square“ (Karl Pearson statistical test and rank ordering method. Trying to elaborate a global conclusion of the questionnaire, there could be noticed the fact that over 50% from the questioned accounting students are not tempted to use the creative accounting practices and techniques in order to optimize the taxation without breaking the actual law regulations. At the opposite side, more than a half from the questioned accounting professionals would use these practices without breaking the law regulations that lead to the taxation’s optimization. The creative accounting has a negative connotation if the accurate image of the financial position and of the performance is not targeted because it represents the essential factor for elaborating and grounding the accounting policies. However, the positive side of the creative accounting is not excluded, given that one appeals to the „fair“ professional judgment of the accounting professionals and to the good faith of managers.

  12. The Study of Heat Transfer on a Heated Circular Surface by an Impinging, Circular Water Jet with the Low Velocity Against the Direction of Gravity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Tae; Eom, Yong Kyoon [Andong National University, Andong (Korea, Republic of)

    2009-12-15

    The heat transfer phenomenon was investigated on this study when a circular water jet with low velocity flows to the downward facing heated circular plate and against the direction of gravity. Data are presented for jet flow rate between 0.23 and 2.3 l/min, jet fluid temperature of 24 .deg. C, heat fluxes between 345 and 687 W/m{sup 2}, H/D=1, 2 and 3 with a single round jet diameter 2mm. The effects of heat flux, jet velocity and H/D on the local heat transfer are investigated in for the various regions of jet impingement. The local heat transfer distributions are analyzed based on the visualization of jet flow field. Data from experimental results are correlated by expressions of the from Nu = 0.01Re{sup 0.58} {center_dot} Pr{sup 0.4}.

  13. The Study of Heat Transfer on a Heated Circular Surface by an Impinging, Circular Water Jet with the Low Velocity Against the Direction of Gravity

    International Nuclear Information System (INIS)

    The heat transfer phenomenon was investigated on this study when a circular water jet with low velocity flows to the downward facing heated circular plate and against the direction of gravity. Data are presented for jet flow rate between 0.23 and 2.3 l/min, jet fluid temperature of 24 .deg. C, heat fluxes between 345 and 687 W/m2, H/D=1, 2 and 3 with a single round jet diameter 2mm. The effects of heat flux, jet velocity and H/D on the local heat transfer are investigated in for the various regions of jet impingement. The local heat transfer distributions are analyzed based on the visualization of jet flow field. Data from experimental results are correlated by expressions of the from Nu = 0.01Re0.58 · Pr0.4

  14. Breaking the fault tree circular logic

    International Nuclear Information System (INIS)

    Event tree - fault tree approach to model failures of nuclear plants as well as of other complex facilities is noticeably dominant now. This approach implies modeling an object in form of unidirectional logical graph - tree, i.e. graph without circular logic. However, genuine nuclear plants intrinsically demonstrate quite a few logical loops (circular logic), especially where electrical systems are involved. This paper shows the incorrectness of existing practice of circular logic breaking by elimination of part of logical dependencies and puts forward a formal algorithm, which enables the analyst to correctly model the failure of complex object, which involves logical dependencies between system and components, in form of fault tree. (author)

  15. Entanglement of quantum circular states of light

    Science.gov (United States)

    Horoshko, D. B.; De Bièvre, S.; Kolobov, M. I.; Patera, G.

    2016-06-01

    We present a general approach to calculating the entanglement of formation for superpositions of two-mode coherent states, placed equidistantly on a circle in phase space. We show that in the particular case of rotationally invariant circular states the Schmidt decomposition of two modes, and therefore the value of their entanglement, are given by analytical expressions. We analyze the dependence of the entanglement on the radius of the circle and number of components in the superposition. We also show that the set of rotationally invariant circular states creates an orthonormal basis in the state space of the harmonic oscillator, and this basis is advantageous for representation of other circular states of light.

  16. Symmetric Circular Matchings and RNA Folding

    DEFF Research Database (Denmark)

    Hofacker, Ivo L.; Reidys, Christian; Stadler, Peter F.

    2012-01-01

    RNA secondary structures can be computed as optimal solutions of certain circular matching problems. An accurate treatment of this energy minimization problem has to account for the small --- but non-negligible --- entropic destabilization of secondary structures with non-trivial automorphisms....... Such intrinsic symmetries are typically excluded from algorithmic approaches, however, because the effects are small, they play a role only for RNAs with symmetries at sequence level, and they appear only in particular settings that are less frequently used in practical application, such as circular...... asymptotic results for both the circular and the co-folding version are derived....

  17. Circular polarization memory in polydisperse scattering media

    CERN Document Server

    Macdonald, Callum M; Meglinski, Igor

    2015-01-01

    We investigate the survival of circularly polarized light in random scattering media. The surprising persistence of this form of polarization has a known dependence on the size and refractive index of scattering particles, however a general description regarding polydisperse media is lacking. Through analysis of Mie theory, we present a means of calculating the magnitude of circular polarization memory in complex media, with total generality in the distribution of particle sizes and refractive indices. Quantification of this memory effect enables an alternate pathway towards recovering particle size distribution, based on measurements of diffusing circularly polarized light.

  18. The phenomenon of transdisciplinary cognitive revolution

    Directory of Open Access Journals (Sweden)

    Bazhanov V. A.

    2016-01-01

    Full Text Available Phenomenon of transdisciplinarity was put into the fore of analysis rather recently. In the article an attempt is made to find out whether it is possible to attribute this phenomenon not only to a science (or even non-classical post-non-classical of the 21st century, or we have here the case where some scientific realities come to the attention of researchers with certain delay and has its value for the culture in general? It is possible to judge even the emergence of a kind of cognitive revolution affecting both science culture. We need to find out what is meant by a transdisciplinarity, and how it differs from the inter- or multiransdisciplinarity. In the study the method of historical reconstruction, combining elements of presentism and antiqurism, was implemented. This method allows us to interpret historical events in the context of a specific level of knowledge, and at the same time to evaluate them in terms of modern ideas related to transdisciplinarity, inter- and multidisciplinarity. System-structural method , focused on an integrated analysis of the dynamics of development of cognitive processes in culture was implied as well, and the method of comparative analysis, which is aimed at comparing different but conceptually similar processes in various areas of conceptual art practice. It is in the framework of (disciplinary based paradigm adopted a tacit agreement among scientists about the validity and effectiveness of research methods and techniques of inquiry. Within the (disciplinary based paradigm, which presupposes certain fundamental principles, goals, and certain values shared by the scientific community, the novel sprouts of radical ideas once emerge. The scientific revolution here means a radical revision of the admissibility of accepted and proven methods, goals and values that are common to the members of the scientific community. Typically, new theories and concepts proposed and already mastered new scientific community

  19. Direct Containment Heating Phenomenon in LWRS

    International Nuclear Information System (INIS)

    Simulation of direct containment heating (DCH) phenomenon for BWR 5 Mark II reactor containment vessel had been performed for the purpose of PSA level 2 study. The accident was assumed to follow a sequence with combination of failure on High Pressure Core Spray System and the failure of manual depressurization of the reactor coolant system leading to core melt-down. The melting core then collapses into the bottom head of the pressure vessel. If the bottom head could not withstand the increasing thermal and pressure loads released by the melts, it would result in the break of the bottom head and subsequent ejection of the core debris to the surface of reactor cavity. During this process, steam containing core debris is then transported to the drywell and containment atmosphere as well as to suppression pool where condensation takes place. Various modes of heat transfer, including radiation, conduction, and convection, and mass transfer take place during this process. The release of such a large amount of heat source could result in increasing pressure of containment atmosphere. The increase in temperature and pressure loads to the containment could be enhanced by metal-water reaction if the temperature reaches the ignition point of this reaction. The simulation assumed release fractions of core debris from reactor vessel to the cavity of 0 %, 10 %, 50 %, and 100 %. The temperature and pressure of the containment atmosphere reach maximum values of 3380 K and 0.726 MPa respectively for the assumed release fraction of core debris of 50 %. This pressure is still below the design pressure of this type of containment, i.e. 0.78 MPa

  20. Electron string phenomenon: physics and use

    Science.gov (United States)

    Donets, Evgeny D.

    2004-01-01

    Electron string phenomenon arises as a result of phase transition of a state of multiply reflected electron beam to this new discovered state of one component electron plasma and can be easily observed in the reflex mode of EBIS operation. The transition goes via a strong instability, which causes considerable electron energy spread, which in its turn suppresses the instability. Electron string state is a stationary state of hot pure electron plasma, which is heated by injected electron beam and cooled because of electron loses. Electron string is quiet in broad regions of experimental parameters, so that it is used for confinement and ionization of positive ions by electron impact to highly charge states similar to electron beams in EBIS. Application of electron strings instead of electron beams for ion production allows to save about 99% of electric power of electron beam and simultaneously to improve reliability of an ion source considerably. The JINR EBIS `Krion-2' in the string mode of operation is used for production of N7+, Ar16+ and Fe24+ ion beams and their acceleration to relativistic energies on the facility of the JINR super conducting one turn injection synchrotron `Nuklotron'. The tubular electron string possibly can exist and it is under study now theoretically and experiments are prepared now. Estimations show that a Tubular Electron String Ion Source (TESIS) could have up to three orders of magnitude higher ion output then a Linear one (LESIS). In frames of nuclear astrophysics electron strings can be used for research of fusion nuclear reactions at low energies in conditions when both beam and target nuclei do not carry orbital electrons. The project NARITA — Nuclear Astrophysics Researches in an Ion Trap Apparatus is proposed. Polarization effects also can be studied.

  1. Sessile Drop Evaporation and Leidenfrost Phenomenon

    Directory of Open Access Journals (Sweden)

    A. K. Mozumder

    2010-01-01

    Full Text Available Problem statement: Quenching and cooling are important process in manufacturing industry for controlling the mechanical properties of materials, where evaporation is a vital mode of heat transfer. Approach: This study experimentally investigated the evaporation of sessile drop for four different heated surfaces of Aluminum, Brass, Copper and Mild steel with a combination of four different liquids as Methanol, Ethanol, Water and NaCl solution. The time of evaporation for the droplet on the hot metallic surface was measured and compared with a proposed correlation as well. With the time temperature plot of these experimental data, the Leidenfrost phenomena had been elucidated. In the pool boiling curve for liquid, just after the transition boiling region and before the film boiling region, the heat transfer approaches its minimum value. The corresponding temperature of this minimum value was termed as the Leidenfrost temperature and the phenomenon is known as Leidenfrost phenomena. According to the experimental data, the Leidenfrost temperature was within a range of 150-200°C for all the experimental conditions. Results: This revealed that Leidenfrost temperature was independent of thermo-physical properties of solid and liquid. Sessile drop evaporation time was the maximum for water, then decreases gradually for Nacl solution, methanol and was the minimum for ethanol for a particular solid material. On the other hand, this time was the highest for copper and the lowest for mild steel for a specific liquid. Conclusion: The experimental data for the evaporation time fairly agree with the proposed correlation within a certain range. The collected time and temperature data may be used as a good data bank for the researchers.

  2. 77 FR 42077 - Environmental Justice: Final Circular

    Science.gov (United States)

    2012-07-17

    ... social service providers to identify transportation challenges and mitigation strategies. FTA is... Register notice (76 FR 60590). II. Chapter-by-Chapter Analysis A. General Comments This section addresses... Circular does not contain any new responsibilities for recipients. Recipients' responsibilities...

  3. Dual frequency launcher for circularly polarized antenna

    Science.gov (United States)

    Chen, Ming H.

    1989-10-01

    A dual frequency antenna feed is formed from a central, circular waveguide connected to the flat boundry of circular, disk-shaped resonant cavity. A second circular waveguide is connected one end of a disk-shaped resonant cavity. Energy of one frequency enters and exits the cavity along the common axis of the waveguides. Energy of the second frequency is introduced to the same resonant cavity by way of a plurality of bandpass filters, also connected to the cavity. This energy enters by way of slots in the cylindrical walls of the cavity. The central circular waveguide is propagating at one frequency but cut off at the second frequency. These bandpass filters are at this pass band for the second frequency, but at the rejection band for the first frequency. Therefore, the isolation between these two input ports are obtained.

  4. Unleashing the Power of the Circular Economy

    Energy Technology Data Exchange (ETDEWEB)

    Kok, L.; Wurpel, G.; Ten Wolde, A. [IMSA Amsterdam, Amsterdam (Netherlands)

    2013-04-15

    The concept of circular economy is an economic and industrial system that focuses on the reusability of products and raw materials, reduces value destruction in the overall system and aims at value creation within each tier of the system. This report for Circle Economy (CE) outlines the general direction and concrete steps that must be taken to accomplish a breakthrough to a circular economy. It also provides a knowledge base behind the concept, connecting it to sustainability.

  5. Construction of Circular Economy Industrial System

    Institute of Scientific and Technical Information of China (English)

    Cao Man; Ye Wenhu

    2007-01-01

    It is difficult to realize the transformation from traditional economy industrial system to circular economy industrial system.Regarding primary raw materials as the indicators,the industrial system has been specified according to the divergence among the indicators and the circular utilization modes.In comparison with the association among industrial systems,the relationship among industrial sub-systems is named as industrial cross-linking in this paper.The industrial system which could completely utilize and recycle the indicators should be increased and strengthened,and the circular economy industrial system with complete industrial association and industrial cross-linking should also be constructed.Taking the development of circular agricultural system basing on the traditional agricultural system as an example,the traditional agricultural products are regarded as the indicators which have been divided into foodstuff and crop straws which are used to produce food and articlesfor use,like fertilizer,energy and papers etc.The way to construct the circular agricultural industrial system is to increase the industrial systems that could utilize the products generated from crop straws,feces and other castoffs and transform the wastewater and other trucks into environmental friendly products.It has also been pointed out that the construction of circular economy industrial system is conducive to the foundation of circular industrial economics and the establishment of the construction layout of circular economy and the application schemes.Suggestions to the theoretical and practical work of the next step have also been brought forward in this paper.

  6. A Conceptual Framework for Circular Design

    Directory of Open Access Journals (Sweden)

    Mariale Moreno

    2016-09-01

    Full Text Available Design has been recognised in the literature as a catalyst to move away from the traditional model of take-make-dispose to achieve a more restorative, regenerative and circular economy. As such, for a circular economy to thrive, products need to be designed for closed loops, as well as be adapted to generate revenues. This should not only be at the point of purchase, but also during use, and be supported by low-cost return chains and reprocessing structures, as well as effective policy and regulation. To date, most academic and grey literature on the circular economy has focused primarily on the development of new business models, with some of the latter studies addressing design strategies for a circular economy, specifically in the area of resource cycles and design for product life extension. However, these studies primarily consider a limited spectrum of the technical and biological cycles where materials are recovered and restored and nutrients (e.g., materials, energy, water are regenerated. This provides little guidance or clarity for designers wishing to design for new circular business models in practice. As such, this paper aims to address this gap by systematically analysing previous literature on Design for Sustainability (DfX (e.g., design for resource conservation, design for slowing resource loops and whole systems design and links these approaches to the current literature on circular business models. A conceptual framework is developed for circular economy design strategies. From this conceptual framework, recommendations are made to enable designers to fully consider the holistic implications for design within a circular economy.

  7. Dual-band Omnidirectional Circularly Polarized Antenna

    OpenAIRE

    Narbudowicz, Adam; Bao, Xiulong; Ammann, Max

    2013-01-01

    A dual-band omnidirectional circularly polarized antenna is proposed. The antenna comprises back-to-back microstrip patches fed by a coplanar waveguide. A very low frequency ratio of 1.182 has been achieved, which can be easily tuned by adjusting four lumped capacitors incorporated into the antenna. An analysis of the omnidirectional circular polarization mechanism as well the dual band operation is provided and confirmed by numerical and experimental data. Key parameters to tune the resonant...

  8. Single particle dynamics in circular accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, R.D.

    1986-10-01

    The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

  9. CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS

    International Nuclear Information System (INIS)

    Solar flare emissions in the chromosphere often appear as elongated ribbons on both sides of the magnetic polarity inversion line (PIL), which has been regarded as evidence of a typical configuration of magnetic reconnection. However, flares having a circular ribbon have rarely been reported, although it is expected in the fan-spine magnetic topology involving reconnection at a three-dimensional (3D) coronal null point. We present five circular ribbon flares with associated surges, using high-resolution and high-cadence Hα blue wing observations obtained from the recently digitized films of Big Bear Solar Observatory. In all the events, a central parasitic magnetic field is encompassed by the opposite polarity, forming a circular PIL traced by filament material. Consequently, a flare kernel at the center is surrounded by a circular flare ribbon. The four homologous jet-related flares on 1991 March 17 and 18 are of particular interest, as (1) the circular ribbons brighten sequentially, with cospatial surges, rather than simultaneously, (2) the central flare kernels show an intriguing 'round-trip' motion and become elongated, and (3) remote brightenings occur at a region with the same magnetic polarity as the central parasitic field and are co-temporal with a separate phase of flare emissions. In another flare on 1991 February 25, the circular flare emission and surge activity occur successively, and the event could be associated with magnetic flux cancellation across the circular PIL. We discuss the implications of these observations combining circular flare ribbons, homologous jets, and remote brightenings for understanding the dynamics of 3D magnetic restructuring.

  10. On the circular polarization of pulsar radiation

    OpenAIRE

    Lyubarskii, Y. E.; Petrova, S. A.

    1999-01-01

    We consider the polarization behaviour of radio waves propagating through an ultrarelativistic highly magnetized electron-positron plasma in a pulsar magnetosphere. The rotation of magnetosphere gives rise to the wave mode coupling in the polarization-limiting region. The process is shown to cause considerable circular polarization in the linearly polarized normal waves. Thus, the circular polarization observed for a number of pulsars, despite the linear polarization of the emitted normal wav...

  11. Angle-resolved x-ray circular and magnetic circular dichroisms: Definitions and applications

    OpenAIRE

    Tong, DSY; X Guo; Tobin, JG; Waddill, GD

    1996-01-01

    We introduce definitions of angle-resolved x-ray circular dichroism (ARXCD) and magnetic x-ray circular dichroism (ARMXCD). As defined, the much larger effect of circular dichroism (ARXCD) is separated from the smaller magnetic (ARMXCD) effect. In all materials, ARXCD is zero along mirror planes while nonzero elsewhere. ARMXCD is nonzero only in magnetic materials. The measurement and analysis of ARMXCD allow element specific surface magnetism and surface structure as well as their inter-rela...

  12. Broadband circularly polarized planar antenna using partially covered circular wide-slot and L-probe

    OpenAIRE

    Fukusako, Takeshi; Sakami, Ryo; Iwata, Kazuki; フクサコ, タケシ; サカミ, リョウ; イワタ, カズキ; 福迫, 武; 酒見, 遼; 岩田, 一樹

    2008-01-01

    The novel structure of a unique circularly polarized broadband antenna that combines an L-shaped probe with a partially covered circular slot has been presented. A principle that can be used to generate CP using the proposed structure has been presented using an L-shaped probe and a modified circular wide slot. Using the above, a 3 -dB AR bandwidth of 58% and matching bandwidth of 57% were obtained at 3.2 GHz.

  13. Exciton circular dichroism in channelrhodopsin.

    Science.gov (United States)

    Pescitelli, Gennaro; Kato, Hideaki E; Oishi, Satomi; Ito, Jumpei; Maturana, Andrés Daniel; Nureki, Osamu; Woody, Robert W

    2014-10-16

    Channelrhodopsins (ChRs) are of great interest currently because of their important applications in optogenetics, the photostimulation of neurons. The absorption and circular dichroism (CD) spectra of C1C2, a chimera of ChR1 and ChR2 of Chlamydomonas reinhardtii, have been studied experimentally and theoretically. The visible absorption spectrum of C1C2 shows vibronic fine structure in the 470 nm band, consistent with the relatively nonpolar binding site. The CD spectrum has a negative band at 492 nm (Δε(max) = -6.17 M(-1) cm(-1)) and a positive band at 434 nm (Δε(max) = +6.65 M(-1) cm(-1)), indicating exciton coupling within the C1C2 dimer. Time-dependent density functional theory (TDDFT) calculations are reported for three models of the C1C2 chromophore: (1) the isolated protonated retinal Schiff base (retPSB); (2) an ion pair, including the retPSB chromophore, two carboxylate side chains (Asp 292, Glu 162), modeled by acetate, and a water molecule; and (3) a hybrid quantum mechanical/molecular mechanical (QM/MM) model depicting the binding pocket, in which the QM part consists of the same ion pair as that in (2) and the MM part consists of the protein residues surrounding the ion pair within 10 Å. For each of these models, the CD of both the monomer and the dimer was calculated with TDDFT. For the dimer, DeVoe polarizability theory and exciton calculations were also performed. The exciton calculations were supplemented by calculations of the coupling of the retinal transition with aromatic and peptide group transitions. For the dimer, all three methods and three models give a long-wavelength C2-axis-polarized band, negative in CD, and a short-wavelength band polarized perpendicular to the C2 axis with positive CD, differing in wavelength by 1-5 nm. Only the retPSB model gives an exciton couplet that agrees qualitatively with experiment. The other two models give a predominantly or solely positive band. We further analyze an N-terminal truncated mutant

  14. Powerful Radio Burst Indicates New Astronomical Phenomenon

    Science.gov (United States)

    2007-09-01

    Astronomers studying archival data from an Australian radio telescope have discovered a powerful, short-lived burst of radio waves that they say indicates an entirely new type of astronomical phenomenon. Region of Strong Radio Burst Visible-light (negative greyscale) and radio (contours) image of Small Magellanic Cloud and area where burst originated. CREDIT: Lorimer et al., NRAO/AUI/NSF Click on image for high-resolution file ( 114 KB) "This burst appears to have originated from the distant Universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole," said Duncan Lorimer, Assistant Professor of Physics at West Virginia University (WVU) and the National Radio Astronomy Observatory (NRAO). The research team led by Lorimer consists of Matthew Bailes of Swinburne University in Australia, Maura McLaughlin of WVU and NRAO, David Narkevic of WVU, and Fronefield Crawford of Franklin and Marshall College in Lancaster, Pennsylvania. The astronomers announced their findings in the September 27 issue of the online journal Science Express. The startling discovery came as WVU undergraduate student David Narkevic re-analyzed data from observations of the Small Magellanic Cloud made by the 210-foot Parkes radio telescope in Australia. The data came from a survey of the Magellanic Clouds that included 480 hours of observations. "This survey had sought to discover new pulsars, and the data already had been searched for the type of pulsating signals they produce," Lorimer said. "We re-examined the data, looking for bursts that, unlike the usual ones from pulsars, are not periodic," he added. The survey had covered the Magellanic Clouds, a pair of small galaxies in orbit around our own Milky Way Galaxy. Some 200,000 light-years from Earth, the Magellanic Clouds are prominent features in the Southern sky. Ironically, the new discovery is not part of these galaxies, but rather is much more distant

  15. PLANAR MOTION OF A SLIGHTLY DISTORTED CIRCULAR CYLINDER AROUND ANOTHER CIRCULAR ONE

    Institute of Scientific and Technical Information of China (English)

    SUN Ren; CHWANG Allen T.

    2004-01-01

    Accurate prediction of the motion of a body moving around another one in an unbounded fluid and determi-nation of the hydrodynamic interaction between them are im-portant in the coastal and offshore engineering. For two-dimensional cases, most of the previous studies were focused on the interaction between circular cylinders without considering the non-circular situation. To break through the limitation of"circular" bodies, in the present paper the boundary perturbation method was employed to investigate the motion of a slightly distorted circular cylinder around a circular one. An approximate complex velocity potential in terms of double infinite series expanded at two singular points was derived using the method of continued fractions. The hydrodynamic interaction between two cylinders was computed by solving the dynamical equations of motion. In a relative coordinate system moving with the uniform stream, the kinetic energy of the fluid was expressed as a function of fifteen added masses. Approximate analytical solutions of added masses in the series form were obtained and applied to determine the trajectories of the slightly distorted circular cylinder around a fixed circular one. Numerical results show that the presence of the circular cylinder affects the planar motion of the slightly distorted cirular cylinder and the initial configuration of the slightly distorted circular cylinder has a decisive influence on the development of its rotational motion.

  16. A fast response temperature sensor based on fiber Bragg grating

    International Nuclear Information System (INIS)

    Aimed at the requirement for a fast-response expendable ocean temperature sensor, this paper presents a new design scheme for an optic fiber sensor. Ocean temperature sensors require high sensitivity and high response speed, which must be up to milliseconds. The fiber Bragg grating (FBG) temperature sensor with high sensitivity has been declared in the last decade, but its response speed has been rarely reported. In this paper, a method is proposed which is to package an FBG with a metal tube. The response time of this sensor is 48.6 ms, which is an order of magnitude greater than that of an ordinary optical fiber temperature sensor. Temperature sensitivity is 27.6 pm/°C and the linearity is up to 0.9999. In addition, the sensor can be less than 15 mm. It offers a new way to detect ocean temperature. (paper)

  17. Humidity insensitive TOPAS polymer fiber Bragg grating sensor

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Khan, Lutul; Webb, David J.;

    2011-01-01

    We report the first experimental demonstration of a humidity insensitive polymer optical fiber Bragg grating (FBG), as well as the first FBG recorded in a TOPAS polymer optical fiber in the important low loss 850nm spectral region. For the demonstration we have fabricated FBGs with resonance...... wavelength around 850 nm and 1550 nm in single-mode microstructured polymer optical fibers made of TOPAS and the conventional poly (methyl methacrylate) (PMMA). Characterization of the FBGs shows that the TOPAS FBG is more than 50 times less sensitive to humidity than the conventional PMMA FBG in both...... wavelength regimes. This makes the TOPAS FBG very appealing for sensing applications as it appears to solve the humidity sensitivity problem suffered by the PMMA FBG....

  18. Prospects for solar axion searches with crystals via Bragg scattering

    International Nuclear Information System (INIS)

    A calculation of the expected signal due to Primakov coherent conversion of solar axions into photons via Bragg scattering in several solid-state detectors is presented and compared with present and future experimental sensitivities. The axion window ma > or approx. 0.03 eV (not accessible at present by other techniques) could be explored in the foreseeable future with crystal detectors to constrain the axion-photon coupling constant gaγγ below the latest bounds coming from helioseismology. On the contrary a positive signal in the sensitivity region of such devices would imply revisiting other more stringent astrophysical limits derived for the same range of the axion mass. The application of this technique to the COSME germanium detector which is taking data at the Canfranc Underground Laboratory leads to a 95% C.L. limit gaγγ ≤ 2.8 x 10-9 GeV-1

  19. Fiber Bragg grating strain sensor for hard rocks

    Science.gov (United States)

    Castro-Caicedo, Alvaro; Nieto-Callejas, María. J.; Torres, Pedro

    2015-09-01

    Strain is an important property to be measured in rock structures such as tunnels, slopes, dams, and mining. However, commercial surface mountable fiber Bragg grating (FBG) strain sensors are packaged in planar configuration, which is not appropriate for the irregular surface of the rocks since an unacceptable bonding layer fails to transfer the strain from the rock to the FBG. As a first approach to this problem, in this work we analyze packaged FBG sensors for cylindrical samples of hard rocks. A calibration process was carried out to evaluate the performance of the packaging and bonding layer as compared to electrical resistance strain gage methods. We show the importance of both packaging and bonding layer in FBG sensor technology for measuring strain in hard rocks.

  20. Microwave Bragg-scattering zone-axis-pattern analysis

    CERN Document Server

    Fraundorf, P; Garver, W; Freeman, M; Proctor, D

    2013-01-01

    Louis deBroglie's connection between momentum and spatial-frequency vectors is perhaps most viscerally-experienced via the real-time access that electron-diffraction provides to transverse slices of a crystal's reciprocal lattice. The classic introductory (and/or advanced) physics lab-experiment on microwave Bragg-scattering can with a bit of re-arrangement also give students access to "zone-axis-pattern" slices through the 3D spatial-frequency (i.e. reciprocal) lattice of a ball-bearing crystal. In this paper we show how data from the standard experimental set up can be used to generate zone-axis-patterns oriented down the crystal rotation-axis. This may be used to give students direct experience with crystal shape-transforms (which help to explain anomalous peaks), as well as to the complementary relation between non-Cartesian basis-vectors in direct and reciprocal (co-vector) space.

  1. Wavefront distortion optimized with volume Bragg gratings in photothermorefractive glass.

    Science.gov (United States)

    Gao, Fan; Zhang, Xiang; Sun, Xiaojie; Yuan, Xiao

    2016-03-15

    The wavefront characteristics in 2D angular filtering on the basis of two orthogonal transmitting volume Bragg gratings (VBGs) is presented. The experimental results show that middle-high frequency wavefront distortions are efficiently suppressed with VBGs. The peak-valley value of the beam at a wavelength of 1053 nm reduces from 2.075λ to 0.209λ, and the root mean square value reduces from 0.207λ to 0.041λ. The wavefront power spectrum density shows that the wavefront distribution of the beam in medium and high frequencies is corrected by the VBGs. Additionally, the far-field distribution and focusing properties of the beam are improved. The beam Strehl ratio increases from 0.43 to 0.96, and the encircled energy improves from 95% energy at 4.01 mrad to 95% energy at 1.26 mrad. PMID:26977639

  2. Fiber Bragg grating demodulation through innovative numerical procedures

    Science.gov (United States)

    Dinardo, Giuseppe; Vacca, Gaetano

    2016-01-01

    The aim of this article is to introduce an innovative algorithm for the calculation of the shift of the maximum reflectivity wavelength of a Fiber Bragg Grating experiencing an applied strain. An accurate and precise evaluation of the FBG spectrum displacement is crucial for determining the amount of the physical quantity inducing such perturbations. The proposed method is based on the Fast Fourier Transform based Cross Correlation function. Such method is compared to Least Squares Fitting (LSF) and the centroid algorithms, pointing out remarkable improvements in accuracy, precision, and time consumption performance. In addition, a further improvement of the proposed algorithm is introduced. It consists in an iteratively performed Cross Correlation algorithm. It has been proved that such improvement leads to estimations characterized by better accuracy and precision, thanks also to a considerable reduction of the peak-locking effect due to the FBG spectral resolution.

  3. Bragg diffraction and the Iron crust of Neutron Stars

    CERN Document Server

    Llanes-Estrada, Felipe J

    2009-01-01

    If neutron stars have a thin atomic crystalline-iron crust, they must diffract X-rays of appropriate wavelength. So that the diffracted beam is visible from Earth, the illuminating source must be very intense and near the reflecting star. An example is a binary system with two neutron stars, one of them inert, the other an X-ray pulsar, in close orbit. The observable to be searched for is a secondary peak added (quasi-) periodically to the main X-ray pulse. The distinguishing feature of this secondary is that it appears at wavelengths related by simple integer numbers, lambda, lambda/2, lambda/3... lambda/n because of Bragg's diffraction law.

  4. Dynamic and static strain gauge using superimposed fiber Bragg gratings

    International Nuclear Information System (INIS)

    This paper demonstrates a simple and fast interrogation method for the dynamic and/or static strain gauge using a reflection spectrum from two superimposed fiber Bragg gratings (FBGs). The superimposed FBGs are designed to decrease nonequidistant space of generated a sensing pulse train in a time domain during dynamic strain gauge. By combining centroid finding with smooth filtering methods, both the interrogation speed and accuracy are improved. A four times increase in the interrogation speed of dynamic strain, by generating a 2 kHz optical sensing pulse train from a 500 Hz scanning frequency, is demonstrated experimentally. The interrogation uncertainty and total harmonic distortion characterization of superimposed FBGs are tested and less than 4 pm standard deviation is obtained. (paper)

  5. Fiber Bragg grating (FBG) sensors used in coal mines

    Science.gov (United States)

    Wang, Jinyu; Liu, Tongyu; Song, Guangdong; Xie, Hongjing; Li, Lianqing; Deng, Xiaolin; Gong, Zhijie

    2014-06-01

    The fiber Bragg grating (FBG) strain sensors were used for on-line monitoring of the stress variation of the lined wall in the gateway retained along the goaf of No. 3203 coal mining face in Dongtan Mine. The results showed that the FBG strain sensor with the wide measuring range could measure the stress variation accurately during the support process of the gateway retained along the goaf and could provide the basis to further optimize the support structure and to determine the support plan of the gateway retained along the goaf. The FBG micro-seismic sensors were used in Xinglong Mine to detect the micro-seismic signal. The signals were well received and analyzed to determine the location and energy level of the source of the micro-seismic event warning. The FBG sensors and detecting system show a significant potential for micro-seismic detection and geological disasters detection.

  6. Contact microphone using optical fibre Bragg grating technology

    International Nuclear Information System (INIS)

    A contact microphone using optical fibre Bragg grating has been developed. It enables one to listen and record a human voice and/or breathing by monitoring the vibration generated by the outer wall of the throat during speech. This system can have many applications such as detecting defects in vocal folds, measuring and monitoring the vibration and defection generated by intubations of a patient throat and other voice related problem, low level speaking recording and transmitting is also possible, the microphone can be also used to monitor breathing and the system can be used as a microphone in very harsh environments for example it would allow one to hear the patient during a cat scan

  7. Contact microphone using optical fibre Bragg grating technology

    Energy Technology Data Exchange (ETDEWEB)

    Bezombes, F A; Lalor, M J; Burton, D R [General Engineering Research Institute (GERI), Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool (United Kingdom)

    2007-07-15

    A contact microphone using optical fibre Bragg grating has been developed. It enables one to listen and record a human voice and/or breathing by monitoring the vibration generated by the outer wall of the throat during speech. This system can have many applications such as detecting defects in vocal folds, measuring and monitoring the vibration and defection generated by intubations of a patient throat and other voice related problem, low level speaking recording and transmitting is also possible, the microphone can be also used to monitor breathing and the system can be used as a microphone in very harsh environments for example it would allow one to hear the patient during a cat scan.

  8. Research of embedded fiber Bragg grating temperature sensor system

    Science.gov (United States)

    Hu, Ji; Wan, Shengpeng; Xie, Changlin; Zhang, Zhimin; Luo, Ningning; He, Shuai

    2010-10-01

    In this article, an embedded fiber Bragg grating temperature sensor system is proposed and researched. The demodulating system controls a Piezoelectric Ceramic (PZT) with sawteeth wave to scan the matching grating, then do photoelectric conversion using a detector, and use Digital Signal Processor (DSP) to find the max intensity. Meanwhile, use PZT drive voltage to control the central wavelength of sensor grating to demodulate. Then use the USB interface chip to realize the communication between DSP and the host computer, and send the collected data to the host computer. Finally, the real time temperature can be inquired and stored through the inquiring interface programmed by computer. The result demonstrates that this experimental system has the wave addressing range from 1540 to 1565 nm and the temperature resolution of 0.1°C.

  9. Fibre Bragg grating based accelerometer with extended bandwidth

    Science.gov (United States)

    Basumallick, Nandini; Biswas, Palas; Chakraborty, Rajib; Chakraborty, Sushanta; Dasgupta, Kamal; Bandyopadhyay, Somnath

    2016-03-01

    We have shown experimentally that the operable bandwidth of a fibre Bragg grating (FBG) based accelerometer can be extended significantly, without compromising its sensitivity, using a post-signal processing technique which involves frequency domain weighting. It has been demonstrated that using the above technique acceleration can be correctly interpreted even when the operating frequency encroaches on the region where the frequency response of the sensor is non-uniform. Two different excitation signals, which we often encounter in structural health monitoring applications, e.g. (i) a signal composed of multi-frequency components and (ii) a sinusoidal excitation with a frequency sweep, have been considered in our experiment. The results obtained have been compared with a piezo accelerometer.

  10. Remote (250 km Fiber Bragg Grating Multiplexing System

    Directory of Open Access Journals (Sweden)

    Manuel Lopez-Amo

    2011-09-01

    Full Text Available We propose and demonstrate two ultra-long range fiber Bragg grating (FBG sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6–8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system.

  11. Notes on Evanescent Wave Bragg-Reflection Waveguides

    CERN Document Server

    Pressl, Benedikt

    2013-01-01

    We investigate an extended version of the Bragg reflection waveguide (BRW) with air gaps as one of the layers. This design has the potential of drastically simplifying the epitaxial structure for integrated nonlinear optical elements at the expense of more complicated structuring. This approach would afford much more flexibility for designing and varying BRW structures. Here, we discuss an extension of the established theory for BRW slabs and report our results of applying Marcatili's method for rectangular waveguides to the BRW case. With this analytic approach we can estimate the effective index of the modes orders of magnitudes faster than with full numerical techniques such as finite-difference time-domain (FDTD) or finite elements. Initial results are mixed; while phase-matched designs have been found, they currently have no significant advantage over other schemes.

  12. Pure Bending Characteristic of Tilted Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    Bo Liu; Yin-Ping Miao; Hai-Bin Zhou; Qi-Da Zhao

    2008-01-01

    a novel structure of the pure macro-bending sensor based on the tilted fiber Bragg grating (TFBG) is proposed. The TFBG located in the half circle with the different diameters is bent at a constant angle with respect to the tilted grating planes. With the variations of the curvature, the core-mode resonance is unchanged and the transmission power of cladding modes detected by the photodiodes varies linearly with curvature, while the ghost mode changes by the form of two-order polynomial. So we can use the transmission power of ghost mode or other cladding modes to detect bending curvature as shape sensor. From a practical point of view, the sensor proposed here is simple, low cost and easy to implement. Moreover, it is possible to make a temperature-insensitive shape sensor due to the same temperature characteristic between the core mode and the cladding modes.

  13. Modulational instability in a fibre and a fibre Bragg grating

    International Nuclear Information System (INIS)

    In this review article, we study the influence of cross-phase modulation, higher order nonlinear effects such as self-steepening, self-induced Raman scattering and higher order dispersion effects such as third and fourth order dispersion on cross-phase modulational instability for a highly elliptical birefringent optical fibre, and obtain the conditions for the occurrence of cross-phase modulational instability in the normal dispersion regime. In addition, we also consider the pulse propagation through a fibre Bragg grating structure where we investigate the occurrence of modulational instability at the two edges of the photonic bandgap as well as on the upper and lower branches of the dispersion curves. (review article)

  14. Femtosecond soliton diode on heterojunction Bragg-grating structure

    CERN Document Server

    Deng, Zhigui; Li, Hongji; Fu, Shenhe; Liu, Yikun; Xiang, Ying; Li, Yongyao

    2016-01-01

    We numerically propose a scheme for realizing an all-optical femtosecond soliton diode based on a tailored heterojunction Bragg grating, which is designed by two spatially asymmetric chirped cholesteric liquid crystals. Our simulations demonstrate that with the consideration of optical nonlinearity, not only the femtosecond diode effect with nonreciprocal transmission ratio up to 120 can be achieved, but also the optical pulse evolving into soliton which maintains its shape during propagation through the sample is observed. Further, the influence of pulse width and the carrier wavelength to the femtosecond diode effect is also discussed in detail. Our demonstrations might suggest a new direction for experimentally realizing the femtosecond soliton diode based on the cholesteric liquid crystals.

  15. Direct UV-written planar Bragg grating sensors

    International Nuclear Information System (INIS)

    Integrated photonics is a proven platform for physical and chemical sensing. It offers miniaturised solutions that are suited for use in extreme environments, including strong EM-fields, EM-pulses and contact with flammable materials, often far exceeding electronic sensors in this regard. This review looks into direct UV-written planar Bragg grating technology and its application to integrated photonic sensors. The platform has been demonstrated widely for measurement of physical properties such as temperature, pressure and strain. In addition, by using an evanescent interaction, refractive index can be measured allowing for chemical and biochemical detection. Further to this, the platform has recently been utilised in quantum information processing, where quantum gate operations and single photon detection has been shown. (topical review)

  16. Vibration measurement of electrical machines using integrated fibre Bragg gratings

    Science.gov (United States)

    Fabian, M.; Borg Bartolo, J.; Ams, M.; Gerada, C.; Sun, T.; Grattan, K. T. V.

    2015-09-01

    In this paper a method to track the rotating force vector set up within the air-gap of radial flux rotating electrical machines using fibre Bragg gratings is reported. The proposed technique offers the potential for simultaneous rotor speed and position monitoring. This specific sensor design, together with other FBG-based multi-parameter measurements, is aimed to create an all-optical sensor solution for electrical machines, reducing the component count of existing systems and addressing noise issues traditionally associated with electrical sensors used. In this work, an optical fibre sensor system has been successfully integrated into an off-the-shelf four-pole 11kW induction motor.

  17. Fabrication of Dual-Wavelength Fiber Bragg Grating with a Longitudinal Stretch

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; ZHANG Dong-sheng; ZHANG Wei-gang; KAI Gui-yun; DONG Xiao-yi

    2006-01-01

    A method of fabricating dual-wavelength fiber Bragg grating with a uniform phase mask is demonstrated.Theoretical analysis and numerical simulation using Matrix method arc given.The moving exposing technique is adopted.Good control over the grating's reflectivity and the separation of the two Bragg wavelengths is enabled by adjusting the stretch,the length of the grating,and the exposure.A grating with two equal transmission peaks of 19.5 dB is obtained by using this method,and the separation of the two Bragg wavelengths is 0.78 nm.

  18. Bragg-case section topography of growth defects in Si : Ge crystals

    International Nuclear Information System (INIS)

    The samples cut out from Si : Ge crystals with 3% and 1.2% of germanium were studied by means of synchrotron white beam Bragg-case section and projection topography as well as conventional transmission Lang topography. The obtained topographs revealed dominant contrast coming from the segregation of germanium. The use of Bragg-case section topography made possible to follow the shape of growth surfaces inside the crystal. The formation of contrast in Bragg-case section topographs for different orientation of growth surfaces with respect to the incident beam is discussed. The applied methods enabled also revealing growth surface instabilities occurring in some regions of Si : Ge crystals

  19. Planar waveguide tilted Bragg grating refractometer fabricated through physical micromachining and direct UV writing.

    Science.gov (United States)

    Holmes, Christopher; Carpenter, Lewis G; Rogers, Helen L; Sparrow, Ian J G; Gates, James C; Smith, Peter G R

    2011-06-20

    A set of rapid prototyping techniques are combined to construct a laterally-tilted Bragg grating refractometer in a novel planar geometry. The tilted Bragg grating is fabricated in a silica-on-silicon planar substrate using a dual beam direct UV writing (DUW) technique. Lateral cladding mode confinement is subsequently achieved by physically micromachining two trenches either side of the direct UV written waveguide. The resulting device is demonstrated as an effective refractometer, displaying a comparable sensitivity to tilted Bragg gratings in a fiber optical geometry, but with the added advantages of planar integration. PMID:21716485

  20. New imaging using pulsed neutron sources imaging of crystalline structural information by Bragg edge transmission spectroscopy

    International Nuclear Information System (INIS)

    Neutron imaging at a pulsed neutron source can simultaneously give position-dependent neutron transmission spectra of a material. 'Bragg edge' transmission pattern appears at low energy region of the spectrum. Since the Bragg edge transmission spectrum includes various crystalline structural information, e.g., crystal structure, crystalline phase, crystallographic texture, crystallite size and strain, the pulsed neutron imaging using a two-dimensional area detector can non-destructively visualize such the information over the wide area of a material. In this article, principles, features and experimental examples of the Bragg edge transmission imaging that is expected as a new analysis tool for materials science are presented. (author)

  1. Miniature fiber Bragg grating sensor interrogator (FBG-Transceiver) system

    Science.gov (United States)

    Mendoza, Edgar A.; Kempen, Cornelia; Lopatin, Craig

    2007-04-01

    This paper describes recent progress conducted towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-Transceiver TM) system based on multi-channel integrated optic sensor (InOSense TM) microchip technology. The hybrid InOSense TM microchip technology enables the integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogator systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation. The FBG-Transceiver system uses active optoelectronic components monolithically integrated to the InOSense TM microchip, a microprocessor controlled signal processing electronics board capable of processing the FBG sensors signals related to stress-strain and temperature as well as vibration and acoustics. The FBG-Transceiver TM system represents a new, reliable, highly robust technology that can be used to accurately monitor the status of an array of distributed fiber optic Bragg grating sensors installed in critical infrastructures. Its miniature package, low power operation, and state-of-the-art data communications architecture, all at a very affordable price makes it a very attractive solution for a large number of SHM/NDI applications in aerospace, naval and maritime industry, civil structures like bridges, buildings and dams, the oil and chemical industry, and for homeland security applications. The miniature, cost-efficient FBG-Transceiver TM system is poised to revolutionize the field of structural health monitoring and nondestructive inspection market. The sponsor of this program is NAVAIR under a DOD SBIR contract.

  2. Basal cell carcinoma with halo phenomenon in a young female: Significance of dermatoscopy in early diagnosis

    Directory of Open Access Journals (Sweden)

    Pinar Yuksel Basak

    2015-01-01

    Full Text Available Halo phenomenon of nevus may be observed as a circular reaction, although it is unusual around tumors. A 29-year-old woman presented with a pigmented lesion on the cheek since three years. She noted whitening of the skin around the lesion almost after a year following its appearance. Dermatologic examination revealed a pigmented nodular lesion with a hypopigmented halo on the left infraorbital region. The clinical impression was halo nevus, whereas basal cell carcinoma (BCC was considered in dermatoscopic differential diagnosis. The diagnosis was infiltrative-type BCC histopathologically. The persistence of a perilesional halo around an enlarging pigmented lesion should be carefully examined with accompanying dermatoscopic findings even in young patients for early diagnosis of tumoral lesions.

  3. High-sensitivity temperature sensor based on Bragg grating in BDK-doped photosensitive polymer optical fiber

    Institute of Scientific and Technical Information of China (English)

    Xusheng Cheng; Weiwei Qiu; Wenxuan Wu; Yanhua Luo; Xiujie Tian; Qijin Zhang; Bing Zhu

    2011-01-01

    @@ A single-mode polymer optical fiber (POF) with highly photosensitive core doped with benzil dimethyl ketal (BDK) is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum (FWHM) of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating (FBG). The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.%A single-mode polymer optical fiber (POF) with highly photosensitive core doped with benzil dimethyl ketal (BDK) is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum (FWHM) of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating (FBG). The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.

  4. Delayed-choice experiments and Bohr's elementary quantum phenomenon

    International Nuclear Information System (INIS)

    In today's words, ''No elementary quantum phenomenon is a phenomenon until it is a registered ('observed', 'indelibly recorded') phenomenon, 'brought to a close' by 'an irreversible act of amplification'. ''In a delayed-choice experiment, one decides which of one or another complementary feature of a phenomenon the observing device will register after the development of the phenomenon is already under way. Several proposals for such experiments are reviewed. When a delayed-choice experiment is conducted at the cosmological level (light coming to the telescope from a distant quasar by two different gravitationally-bent routes), ''one-half of the ghost of a photon'' can be delayed by a month or a year compared to the ''other half''. The circumstance raises an interesting technical question, ''How can one keep one-half the ghost of a photon alive for a year.'' Bohr's phenomenon is discussed as a primordial building element for all of physics. (author)

  5. OPERATIONAL CIRCULAR NO 6 - JUNE 2001 'CERN SCIENTIFIC DOCUMENTS'

    CERN Multimedia

    Human Resources Division

    2001-01-01

    This new operational circular has been drawn up. It cancels and replaces Administrative Circular N° 29 entitled "Principles and procedures governing CERN publications and reports and other publications arising from CERN work". Copies are available from Divisional Secretariats. Note : Administrative and operational circulars, as well as the lists of those in force, are available for consultation on WWW : ADMINISTRATIVE CIRCULARSOPERATIONAL CIRCULARS

  6. Case report 551: Intraosseous ganglion of olecranon with vacuum phenomenon

    International Nuclear Information System (INIS)

    Intraosseous ganglion of the ulna in a 52-year-old woman is reported. Gas (vacuum phenomenon) in the lesion was documented on CT scan. Vacuum phenomenon may be observed in intraosseous ganglion even if there is no communication with the joint. The clinical, radiological and pathological features of intraosseous ganglion were discussed and the reasons for a vacuum phenomenon were considered. (orig./GDG)

  7. Hockey Stick Phenomenon: Supply Chain Management Challenge in Brazil

    OpenAIRE

    Lars Meyer Sanches; Orlando Fontes Lima Jr.

    2014-01-01

    The objective of this study is to investigate a phenomenon that occurs in Brazil, specifically the spike in demand at the end of the sales period, known as the hockey stick phenomenon. This analysis will encompass the causes as well as the impacts of this phenomenon, in a way that allows alternative policies to be evaluated. Data was collected from a Brazilian branch of a large multinational in the non-durable consumer goods industry and in semi-structured interviews conducted...

  8. Researches on Relationship between Circular Agriculture and Industrial Diversity

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    First, this paper establishes the conceptual model of circular agriculture, conducts systematic analysis on the circular agriculture on the basis of conceptual model, and discusses the characteristics of closeness and openness of circular agriculture and relationship between closeness and openness of circular agriculture. Second, this paper introduces the industrial diversity related to circular agriculture, defines the concept of industry and the concept of industries related to agriculture, and illustrates the related industries that are conducive to circular agriculture and the related industries that are not conducive to circular agriculture. Finally, this paper analyzes the mutual relationship between circular agriculture and industrial diversity as follows: in the system of circular agriculture, the industrial diversity can transform the wastes in upstream industries into resources in downstream industries; the industrial diversity creates possibility for recycling of agricultural byproducts; the industrial diversity is conducive to the diversification of industries related to circular agriculture.

  9. Unsteady flow around two-dimensional circular cylinder bundles in fluid elastic vibration

    International Nuclear Information System (INIS)

    We describe the unsteady flow around two-dimensional circular cylinder bundles supported by the leaf spring in the fluid-elastic vibration. The experiment was carried out in a circuit-type wind tunnel having a 200 mm x 200 mm working section of 2,000 mm length at the Reynolds number Re of 6,300. Two-dimensional circular cylinders with diameter D = 20 mm were aligned at regular spaces S in the square array of three rows. The spacing ratio between two adjoining circular cylinders was constant as S/D = 1.5. The time-mean velocity, turbulent intensities and Reynolds stress were measured by use of a laser Doppler velocimeter. The unsteady flow pattern around an oscillating cylinder was observed by the flow visualization in a water channel. Consequently, it was found that the occurrence of the fluid-elastic vibration is caused by the phenomenon of wake-switch for the circular cylinder bundles of three rows. (author)

  10. Moe fenomen. The Phenomenon of Fashion

    Directory of Open Access Journals (Sweden)

    Ines Piibeleht

    2012-06-01

    Full Text Available Since the last quarter of the 20th century, particularly after the “cultural turn”, the interest in fashion has been increasing in a variety of different disciplines. Fashion has begun to be investigated in many different contexts, using new theoretical approaches. Fashion can be regarded as a social phenomenon, a sign system, as art, myth, or the product of the fashion industry. The purpose of this article is not to provide a definition of fashion, but rather to raise the question of how to approach the experience of fashion analytically. The methodological issues discussed here emerged in the course of preparing for empirical research on fashion. The observations and comparisons that constitute the core of this article are the result of efforts to juxtapose different methods. The traditional history of fashion used a historical-epistemological strategy but, depending on how one defines culture, the meaning of fashion can also be analysed using methods based on different epistemological strategies. The phenomenological method elaborated by Edmund Husserl, which I have chosen for my analysis of the experience of fashion, defines culture through the experiential acts of individuals. Simply stated, phenomenology considers the world as it is given to us in our consciousness. What is most important for empirical research is that the phenomenological method makes it possible to study the structure of a concrete experience and to focus on the mechanisms of the subjective creation of meaning. Thus this article has two main foci: a theoretical analysis of how the experience of fashion can be analytically revealed using the phenomenological method, and a comparison of the phenomenological approach with methods based on other strategies. The analysis of descriptions in the first person makes it possible to highlight how experience has been constructed. People “see” fashion based on structures of meaning; when they describe their own experience

  11. Total and Differential Efficiencies for a Circular Detector Viewing a Circular Radiator of Finite Thickness

    International Nuclear Information System (INIS)

    Total and differential detection efficiencies have been computed for a circular detector viewing a circular radiator of finite thickness. Isotropic, cosines and n-p scattering angular emission distributions of the radiated particles are considered. Tables are given for the total efficiencies as well as for the differential efficiencies in the n-p scattering case

  12. Study on Dual Bragg Wavelength Fiber Grating and Its Tuning Scheme

    Institute of Scientific and Technical Information of China (English)

    Dong Xingfa; Fu Shenggui; Zhang Hao; Kai Guiyun; Dong Xiaoyi

    2003-01-01

    Because of package, a single FBG has dual Bragg wavelength. One is sensitive to stress and the other is sensitive to temperature. By using the special mechanism, the wavelengths can be tuned by stress and temperature respectively.

  13. High Power Compact Single-Frequency Volume Bragg Er-Doped Fiber Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is based on successful results of Phase I project where it was shown that the use of volume Bragg gratings in PTR glass as selectors of transverse and...

  14. Impact of Saturable Gain/Loss on Bistability of Nonlinear Parity-Time Bragg Gratings

    CERN Document Server

    Phang, Sendy; Susanto, Hadi; Benson, Trevor M; Sewell, Phillip

    2014-01-01

    We report on the impact of realistic gain and loss models on the bistable operation of nonlinear parity-time Bragg gratings. In our model we include both dispersive and saturable gain and show that levels of gain/loss saturation can have significant impact on the bistable operation of a nonlinear PT Bragg grating based on GaAs material. The hysteresis of the nonlinear PT Bragg grating is analyzed for different levels of gain and loss and different saturation levels. We show that high saturation levels can improve the nonlinear operation by reducing the intensity at which the bistability occurs. However when the saturation intensity is low, saturation inhibits PT phenomena in a nonlinear PT Bragg grating.

  15. Fiber sensing system based on a bragg grating and optical time domain reflectometry

    OpenAIRE

    Chin, Sanghoon; Thévenaz, Luc

    2013-01-01

    Optic fiber sensor characterized in that the sensing fiber is provided with a continuous Bragg grating covering the entire fiber length which is dedicated to sensing and along which spatially resolved measurements are performed.

  16. Development of a Fibre Bragg Grating Sensor for Rock Deformation Monitoring

    Science.gov (United States)

    Kanopoulos, Patrick Paskalis

    This thesis examines the theoretical and experimental performance of a fibre Bragg grating sensor for static and dynamic strain measurement in hard rock. A literature review focuses on the fundamental theory of fibre Bragg gratings, various physical demodulation schemes used to interrogate Bragg sensors with an emphasis on charge coupled device spectrometry, as well as the aliasing behaviour of Bragg gratings as sensors. A coupled numerical-analytical analysis is conducted on various sensor configurations designed for borehole deployment in order to establish the response of the strain sensors under various strain conditions. The findings of an experimental investigation of two sensors subjected to uniaxial strain within a grout and a rock specimen are presented. The experimental data confirm the feasibility of using the proposed sensor as a part of an integrated optical strain sensing network.

  17. Analysis of Sampled Fiber Bragg Grating Based on the Photonic Crystal Theory

    Institute of Scientific and Technical Information of China (English)

    ZHU Dan-dan

    2009-01-01

    One of the most basic characteristics of photonic crystal is frequency band gap.When defects are introduced into the periodic photonic crystal,a number of defect modes appear in the stop band.In this paper,we exploit transfer matrix method based on photonic crystal theory,and assume the sampled fiber Bragg grating as one-dimensional dual photonic crystal with a large size defect.Characteristics of the sampled fiber Bragg grating are analyzed.Experimental results show that the sampled fiber Bragg grating has many reflective peaks.Its reflectivity,center wavelength,reflective peak intervals and band width all change with the grating parameters,including grating length,duty ratio of the material with high dielectric constant,and index modulation depth and period.Results agree with the conventional couple mode theory which can be used when analyzing other characteristics of the sampled fiber Bragg grating or applying it into practice.

  18. Extending Bragg peak of heavy ion beam and melanoma cell inactivation measurement

    Institute of Scientific and Technical Information of China (English)

    LiQiang; WeiZeng-Quan; 等

    1998-01-01

    A rotating range modulator was designed and manufactured.which is applied to extend Bragg peak of heavy ion beam.Bragg curves of 75MeV/u 16O and 75MeV/u 12C ion beams through this range modulator were measured respectively and two evident spread-out Bragg peaks corresponding to the modulated beams above are shown.In addition,inactivation effect of the modulated 75MeV/u 16O ion beam at nine different penetration depths on melanoma cells(B16) was measured.Results indicate that lethal effects at the spread-out Bragg peak region are larger than at the plateau of the particle beam entrance.

  19. Fiber Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    CERN Document Server

    Abbaneo, D; Abbrescia, M.; Abdelalim, A.A.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Ahmed, W.; Aleksandrov, A.; Aly, R.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F.R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M.M.; De Lentdecker, G.; De Oliveira, R.; De Robertis, G.; Dildick, S.; Dorney, B.; Elmetenawee, W.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R.M.; Hassan, A.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y.G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P.K.; Mandal, K.; Marchioro, A.; Marinov, A.; Masod, R.; Majumdar, N.; Merlin, J.A.; Mitselmakher, G.; Mohanty, A.K.; Mohamed, S.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L.M.; Paolucci, P.; Park, I.; Passeggio, G.; Passamonti, L.; Pavlov, B.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Russo, A.; Ryu, G.; Ryu, M.S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A.H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S.K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2016-01-01

    A novel approach which uses Fibre Bragg Grating (FBG) sensors has been utilised to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

  20. Trends and future of fiber Bragg grating sensing technologies: tailored draw tower gratings (DTGs)

    Science.gov (United States)

    Lindner, E.; Hartung, A.; Hoh, D.; Chojetzki, C.; Schuster, K.; Bierlich, J.; Rothhardt, M.

    2014-05-01

    Today fiber Bragg gratings are commonly used in sensing technology as well as in telecommunications. Numerous requirements must be satisfied for their application as a sensor such as the number of sensors per system, the measurement resolution and repeatability, the sensor reusability as well as the sensor costs. In addition current challenges need to be met in the near future for sensing fibers to keep and extend their marketability such as the suitability for sterilization, hydrogen darkening or the separation of strain and temperature (or pressure and temperature). In this contribution we will give an outlook about trends and future of the fiber Bragg gratings in sensing technologies. Specifically, we will discuss how the use of draw tower grating technology enables the production of tailored Bragg grating sensing fibers, and we will present a method of separating strain and temperature by the use of a single Bragg grating only, avoiding the need for additional sensors to realize the commonly applied temperature compensation.

  1. High-speed two-dimensional laser scanner based on Bragg gratings stored in photothermorefractive glass.

    Science.gov (United States)

    Yaqoob, Zahid; Arain, Muzammil A; Riza, Nabeel A

    2003-09-10

    A high-speed free-space wavelength-multiplexed optical scanner with high-speed wavelength selection coupled with narrowband volume Bragg gratings stored in photothermorefractive (PTR) glass is reported. The proposed scanner with no moving parts has a modular design with a wide angular scan range, accurate beam pointing, low scanner insertion loss, and two-dimensional beam scan capabilities. We present a complete analysis and design procedure for storing multiple tilted Bragg-grating structures in a single PTR glass volume (for normal incidence) in an optimal fashion. Because the scanner design is modular, many PTR glass volumes (each having multiple tilted Bragg-grating structures) can be stacked together, providing an efficient throughput with operations in both the visible and the infrared (IR) regions. A proof-of-concept experimental study is conducted with four Bragg gratings in independent PTR glass plates, and both visible and IR region scanner operations are demonstrated. PMID:14503693

  2. Fiber Bragg Grating (FBG) sensors as flatness and mechanical stretching sensors

    Science.gov (United States)

    Abbaneo, D.; Abbas, M.; Abbrescia, M.; Abdelalim, A. A.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Ahmed, W.; Aleksandrov, A.; Aly, R.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F. R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M. M.; De Lentdecker, G.; De Oliveira, R.; De Robertis, G.; Dildick, S.; Dorney, B.; Elmetenawee, W.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hassan, A.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y. G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P. K.; Mandal, K.; Marchioro, A.; Marinov, A.; Masod, R.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohamed, S.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passeggio, G.; Passamonti, L.; Pavlov, B.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Russo, A.; Ryu, G.; Ryu, M. S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A. H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S. K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2016-07-01

    A novel approach which uses Fiber Bragg Grating (FBG) sensors has been utilized to assess and monitor the flatness of Gaseous Electron Multipliers (GEM) foils. The setup layout and preliminary results are presented.

  3. A broadband, circular-polarization selective surface

    Science.gov (United States)

    Momeni Hasan Abadi, Seyed Mohamad Amin; Behdad, Nader

    2016-06-01

    We introduce a new technique for designing wideband circular-polarization selective surfaces (CPSSs) based on anisotropic miniaturized element frequency selective surfaces. The proposed structure is a combination of two linear-to-circular polarization converters sandwiching a linear polarizer. This CPSS consists of a number of metallic layers separated from each other by thin dielectric substrates. The metallic layers are in the form of two-dimensional arrays of subwavelength capacitive patches and inductive wire grids with asymmetric dimensions and a wire grid polarizer with sub-wavelength period. The proposed device is designed to offer a wideband circular-polarization selection capability allowing waves with left-hand circular polarization to pass through while rejecting those having right-hand circular polarization. A synthesis procedure is developed that can be used to design the proposed CPSS based on its desired band of operation. Using this procedure, a prototype of the proposed CPSS operating in the 12-18 GHz is designed. Full-wave electromagnetic simulations are used to predict the response of this structure. These simulation results confirm the validity of the proposed design concept and synthesis procedure and show that proposed CPSS operates within a fractional bandwidth of 40% with a co-polarization transmission discrimination of more than 15 dB. Furthermore, the proposed design is shown to be capable of providing an extremely wide field of view of ±60°.

  4. Environmental issues elimination through circular economy

    Science.gov (United States)

    Špirková, M.; Pokorná, E.; Šujanová, J.; Samáková, J.

    2016-04-01

    Environmental efforts of European Union are currently going towards circular economy. Tools like Extended Producer Responsibility and Eco-design were established. The circular economy deals with resources availability issue on one hand and waste management on the other hand. There are few pioneering companies all over the world with some kind of circular economy practice. Generally the concept is not very wide-spread. The paper aims to evaluate possibility of transition towards circular economy in Slovak industrial companies. They need to have an active approach to material treatment of their products after usage stage. Innovation is another important pre-condition for the transition. Main problem of current cradle to grave system is landfilling of valuable materials after one cycle of usage. Their potential value for next manufacturing cycles is lost. Companies may do not see connection between waste management and material resource prices and volatility of supplies. Municipalities are responsible for municipal waste collection and treatment in Slovakia. The circular economy operates by cradle to cradle principle. Company manages material flow until the material comes back to the beginning of manufacturing process by itself or by another partners. Stable material supplies with quite low costs are provided this way. It is necessary to deal with environmental problems in phase of product design. Questionnaire survey results show on one hand low involvement of industrial companies in waste management area, however on the other hand they are open to environmental innovations in future.

  5. A COMPACT CIRCULARLY POLARIZED SLOTTED MICROSTRIP ANTENNA

    Directory of Open Access Journals (Sweden)

    V. Jebaraj

    2014-12-01

    Full Text Available Slot antennas are often used at UHF and microwave frequencies. In slot antenna for RFID reader applications the frequency ranges from 902-923MHz to achieve circular polarization. The shapes and size of the slot, as well as the driving frequency, determine the radiation distribution pattern. The proposed compact size circularly polarized slotted microstrip antenna are summarized with design rules. The circularly polarized radiation in square patch antenna can be obtained by perturbation technique with different shapes of slot in the orthogonal direction. A single feed configuration based symmetric slotted microstrip antenna is adapted to realize the compact circularly polarized microstrip antennas. Based on the perimeter, the size of the slot on microstrip slot antenna are studied and compared. The Operating frequency of the antenna is 912MHz that can be tuned by varying the perimeter of the slot while the keeping the circularly polarized radiation unchanged. The schematic and layout are configured by using Advanced Design System (ADS. Return loss, Resonant Frequency, Axial Ratio (AR, and Gain were determined for the proposed system using ADS. A measured 3dB Axial Ratio (AR bandwidth around 6MHz with 16MHz impedance bandwidth has been achieved for the antenna on a RO3004C substrate with dielectric constant 3.38.

  6. Circular Ribbon Flares and Homologous Jets

    CERN Document Server

    Wang, Haimin

    2012-01-01

    Solar flare emissions in the chromosphere often appear as elongated ribbons on both sides of the magnetic polarity inversion line (PIL), and this has been regarded as evidence of a typical configuration of magnetic reconnection. However, flares having a closed circular ribbon have rarely been reported, although it is expected in the fan--spine magnetic topology involving reconnection at a three-dimensional (3D) coronal null point. We present five circular ribbon flares with associated surges, using high-resolution and high-cadence \\ha blue wing observations obtained from the recently digitized films of Big Bear Solar Observatory (BBSO). In all the events, a central parasitic magnetic field is encompassed by the opposite magnetic polarity, forming a circular PIL that is also traced by filament material. Consequently, a flare kernel at the center is surrounded by a circular flare ribbon. The four homologous jet-related flares on 1991 March 17 and 18 are of particular interest, as (1) the circular ribbons bright...

  7. Finite mixture model applied in the analysis of a turbulent bistable flow on two parallel circular cylinders

    International Nuclear Information System (INIS)

    This paper presents a study of the bistable phenomenon which occurs in the turbulent flow impinging on circular cylinders placed side-by-side. Time series of axial and transversal velocity obtained with the constant temperature hot wire anemometry technique in an aerodynamic channel are used as input data in a finite mixture model, to classify the observed data according to a family of probability density functions. Wavelet transforms are applied to analyze the unsteady turbulent signals. Results of flow visualization show a predominantly two-dimensional behavior. A double-well energy model is suggested to describe the behavior of the bistable phenomenon in this case. (author)

  8. Anomalous longitudinal mode hops in GaAs/AlGaAs distributed Bragg reflector lasers

    OpenAIRE

    Hofstetter, Daniel; Zappe, H. P.

    2008-01-01

    We investigate normal and anomalous longitudinal mode hops in GaAs/AlGaAs-based distributed Bragg reflector (DBR) lasers; anomalous mode hops are defined as those which move toward shorter wavelengths with increasing temperature, which is unexpected. The two-section DBR lasers discussed in this letter, consisting of a gain section and an unpumped Bragg reflector, typically exhibit one mode hop in a 10 K temperature range. Although the longer wavelength modes are expected to start lasing when ...

  9. Fiber-optical accelerometers based on polymer optical fiber Bragg gratings

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Stefani, Alessio; Bang, Ole;

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer.......Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  10. An experimental approach to quantify strain transfer efficiency of fibre bragg grating sensors to host structures

    OpenAIRE

    C. Y. Wei; Ye, Chen-Chun; James, Stephen W.; Tatam, Ralph P.; Irving, Phil E.

    2001-01-01

    This paper developed a method to evaluate the strain transfer efficiency of fibre Bragg grating sensors to host structures. Various coatings were applied to fibre Bragg grating sensors after being fabricated. They were epoxy, silane agent and polypropylene, representing different surface properties. A neat epoxy resin plate was used as the host in which the coated fibre sensors were embedded in the central layer. The tensile strain output from the FBGs was compared with that...

  11. Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

    Directory of Open Access Journals (Sweden)

    Abdallah Ikhlef

    2012-01-01

    Full Text Available This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on solving coupled mode equations by transfer matrix method.

  12. Ionoacoustic tomography of the proton Bragg peak in combination with ultrasound and optoacoustic imaging

    OpenAIRE

    Stephan Kellnberger; Walter Assmann; Sebastian Lehrack; Sabine Reinhardt; Peter Thirolf; Daniel Queirós; George Sergiadis; Günther Dollinger; Katia Parodi; Vasilis Ntziachristos

    2016-01-01

    Ions provide a more advantageous dose distribution than photons for external beam radiotherapy, due to their so-called inverse depth dose deposition and, in particular a characteristic dose maximum at their end-of-range (Bragg peak). The favorable physical interaction properties enable selective treatment of tumors while sparing surrounding healthy tissue, but optimal clinical use requires accurate monitoring of Bragg peak positioning inside tissue. We introduce ionoacoustic tomography based ...

  13. Strain and temperature sensors using multimode optical fiber Bragg gratings and correlation signal processing

    OpenAIRE

    Lim, J; Yang, QP; Jones, BE; Jackson, PR

    2002-01-01

    Multimode fiber optic Bragg grating sensors for strain and temperature measurements using correlation signal processing methods have been developed. Two multimode Bragg grating sensors were fabricated in 62/125 m graded-index silica multimode fiber; the first sensor was produced by the holographic method and the second sensor by the phase mask technique. The sensors have signal reflectivity of approximately 35% at peak wavelengths of 835 nm and 859 nm, respectively. Strain testing...

  14. A temperature insensitive Bragg grating sensor - using orthogonal polar polarisation modes for in situ temperature compensation

    OpenAIRE

    Parker, R M; J.C.Gates; Grossel, M. C.; P.G.R.Smith

    2010-01-01

    An exposed Bragg grating incorporated into a planar waveguide forms an optical device that acts as a refractive index sensor. The exposed evanescent field causes the Bragg peak to be sensitive to the refractive index of its surroundings and can be used to detect changes in this environment. The method reported is able to provide accurate temperature compensation by applying a scaling factor derived from measurement of the birefringence of the transverse electric (TE) and transverse magnetic (...

  15. Karakterisasi Fiber Bragg Grating (FBG) Untuk Pengembangan Sistem Sensor Strain Tanah

    OpenAIRE

    Sinuhaji, Depi Santi

    2010-01-01

    Fiber Bragg Grating (FBG) is a periodic change of refractive index which is the length of optical fiber. Has been developed Fiber Bragg Grating (FBG)-based laser diodes for monitoring landslide-prone areas. This sensor has been developed because high sensitivity and is not affected by electromagnetic induction that can be placed at a distance from the location where the power supply and monitor. FBG transmission peak will shift when the grating is change resulting from a change in temperature...

  16. Practical biological spread-out Bragg peak design of carbon beam

    OpenAIRE

    Kim, Chang Hyeuk; Lee, Hwa-Ryun; Chang, Seduk; Jang, Hong Suk; Kim, Jeong Hwan; Park, Dong Wook; Hwang, Won Taek; Yang, Tea-Keun

    2015-01-01

    The carbon beams show more advantages on the biological properties compared with proton beams in radiation therapy. The carbon beam shows high linear energy transfer (LET) to medium and it increases the relative biological effectiveness (RBE). To design spread-out Bragg peak (SOBP) of biological dose using carbon beam, a practical method was purposed by using the linear-quadratic (LQ) model and Geant4 based Monte Carlo simulation code. The various Bragg peak profiles and LET was calculated fo...

  17. 100 GHz electrically tunable planar Bragg gratings via liquid crystal overlay

    OpenAIRE

    Adikan, F.R.Mahamd; J.C.Gates; Snow, B.D.; Dyadyusha, A.; Major, H.E.; Gawith, C.B.E.; Kaczmarek, M.; P.G.R.Smith

    2007-01-01

    We demonstrate 114GHz electrically tunable liquid crystal Bragg gratings using 170Vpp voltage. The devices were made using direct UV grating writing and use evanescent coupling into an electrically tuned nematic liquid crystal. Reconfigurable integrated optical devices are essential in today's dense and complex telecommunication meshes. A commonly employed component on the silica platform fulfilling the above role is a planar Bragg grating. The ability to tune the reflection peak of these gra...

  18. Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

    OpenAIRE

    Abdallah Ikhlef; Rachida Hedara; Mohamed Chikh-Bled

    2012-01-01

    This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on ...

  19. Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

    OpenAIRE

    Hisham K. Hisham

    2016-01-01

    The thermal dependence of the spectral response (i.e. transmission, reflection and time delay (r) responses) of uniform polymer optical fiber (POF) Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg) and fiber index modulation (n) have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings sh...

  20. Floquet-Bloch vs. Nicolson-Ross-Weir Extraction for Magneto-Dielectric Bragg Stacks

    DEFF Research Database (Denmark)

    Clausen, Niels Christian Jerichau; Arslanagic, Samel; Breinbjerg, Olav

    We extract and compare the permittivity and permeability from a dielectric and a magnetodielectric Bragg stack with the Floquet-Bloch (FB) method for the infinite stack and the Nicolson-Ross- Weir (NRW) method for the finite stack. While the extracted propagation constants are identical, the wave...... impedances are different. Moreover, the NRWmethod yields magnetic effects for the dielectric Bragg stack, while the FB method gives the expected vacuum permeability, also in the bandgab....

  1. Fiber Bragg Gratings in Small-Core Ge-Doped Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    Yiping Wang; Hartmut Bartelt; Wolfgang Ecke; Reinhardt Willsch; Jens Kobelke; Michael Kautz; Sven Brueckner; Manfred Rothhardt

    2008-01-01

    This paper reports fiber Bragg gratings (FBGs) inscribed in a small-core Ge-doped photonic crystal fibers with a UV laser and a Talbot inter-ferometer. The responses of such FBGs to temper-ature, strain, bending, and transverse-loading were systematically investigated. The Bragg wavelength of the FBGs shifts toward longer wavelengths with increasing temperature, tensile strain, and trans-verse-loading. The bending and transverse- loading properties of the FBGs are sensitive to the fiber orientations.

  2. Computer-Generated Holograms for Recording Multiple-Phase-Shifte Fiber Bragg Grating Corrugations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new method of fabricating multiple-phase-shifte fiber Bragg grating by CGHs is proposed. The authors present an example of such CGH by which a section multiple-phase-shifte fiber Bragg grating with two π/2 phase shifts and grating length L=21.2 μm was produced. The authors describe the production process and finally give an example of a reconstructed fiber grating with two phase-shifts.

  3. Temperature sensor based on injection fiber Bragg grating laser with wavelength and temporal domain demodulation

    Science.gov (United States)

    Li, Qi; Huang, Kaiqiang; Chen, Haiyan

    2015-08-01

    A novel temperature sensor based on injection fiber Bragg grating laser with wavelength and temporal domain demodulation is proposed and demonstrated experimentally. The proof of concept device consists of a DFB laser modulated by a RF signal as injection light, a fiber Bragg grating laser, an optical spectrum analyzer, and a digital oscilloscope. The dynamic range of the proposed sensor is explored. The results demonstrate the new concept of temperature sensors and the technical feasibility for temperature measurement.

  4. Comparison of spatial harmonics in infinite and finite Bragg stacks for metamaterial homogenization

    DEFF Research Database (Denmark)

    Clausen, Niels Christian Jerichau; Arslanagic, Samel; Breinbjerg, Olav

    2014-01-01

    Metamaterial homogenization may be based on the dominance of a single Floquet-Bloch spatial harmonic in an infinite periodic structure - with the dominance quantified in terms of the relative magnitude of the associated spatial harmonic Poynting vector. For the corresponding finite structure...... of the corresponding infinite Bragg stack. This is even the case for finite Bragg stacks having only two unit cells; thus, the number of unit cells does not influence the homogenizability of this type of configuration. ©...

  5. Numerical Analysis of Thermal Dependence of the Spectral Response of Polymer Optical Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Hisham K. Hisham

    2016-06-01

    Full Text Available The thermal dependence of the spectral response (i.e. transmission, reflection and time delay (r responses of uniform polymer optical fiber (POF Bragg gratings has been investigated. In addition to the temperature dependence, the effects of grating strength (kLg and fiber index modulation (n have been investigated. Besides high capability of tunable wavelength due to the unique large and negative thermo-optic coefficient of POF, the spectral response for POF Bragg gratings show high stability and larger spectrum bandwidth with temperature variation compare with the silica optical fiber (SOF Bragg gratings, especially with the increase of the kLg value. It was found that by increasing kLg, the peak reflectance value increases and the bandwidth of the Bragg reflector become narrower. Also it’s shown by increasing the kLg value, r deceasing significantly and reach its minimum value at the designed wavelength (B. Furthermore, the r for POF Bragg gratings is less than that for SOF Bragg gratings at the same value of kLg. Also it’s found that the peak reflectivity value increases to around 60% when the n value increases from 110-4 to 510-4.

  6. Bragg diffraction of fermions at optical potentials; Braggbeugung von Fermionen an optischen Potentialen

    Energy Technology Data Exchange (ETDEWEB)

    Deh, Benjamin

    2008-10-27

    This thesis describes the Bragg diffraction of ultracold fermions at an optical potential. A moving optical lattice was created, by overlaying two slightly detuned lasers. Atoms can be diffracted at this lattice if the detuning fulfills the Bragg condition for resting atoms. This Bragg diffraction is analyzed systematically in this thesis. To this end Rabi oscillations between the diffraction states were driven, as well in the weakly interacting Bragg regime, as in the strongly interacting Kapitza-Dirac regime. Simulations, based on a driven two-, respectively multilevel-system describe the observed effects rather well. Furthermore, the temporal evolution of the diffracted states in the magnetic trapping potential was studied. The anharmonicity of the trap in use and the scattering cross section for p-wave collisions in a {sup 6}Li system was determined from the movement of these states. Moreover the momentum distribution of the fermions was measured with Bragg spectroscopy and first signs of Fermi degeneracy were found. Finally an interferometer with fermions was build, exhibiting a coherence time of more than 100 {mu}s. With this, the possibility for measurement and manipulation of ultracold fermions with Bragg diffraction could bee shown. (orig.)

  7. Formularization and simulation of Bragg selectivity of readout signals in angular-multiplexing holographic data storage.

    Science.gov (United States)

    Ide, Tatsuro

    2016-04-01

    Bragg selectivity of readout signals in angular-multiplexing holographic data storage was investigated. The effects of degrading factors, namely, volume change, refractive-index change, and positional change (tilt and rotation) of a hologram, and the effects of compensating variables, namely, wavelength shift and reference-beam-angle shift, on Bragg selectivity were evaluated. Deviation of wave vectors of recovered pixels of a hologram from the Bragg condition under degrading factors and compensating variables, namely, Bragg mismatch, Δσ, was mathematically derived. Approximating Δσ by using the first-order Maclaurin series with respect to degrading factors and compensating variables revealed their effects on Bragg selectivity. The extent to which wavelength and angle of reference beam should be shifted to compensate for the degrading factors were determined. Then, readout images were simulated under multiple degrading factors and compensating variables. These simulated images were found to agree well with the experimentally obtained ones, which reveals the validity of the formalization of Bragg selectivity. PMID:27139671

  8. The Functionality of Fiber Bragg Grating Sensor Compared to that of Foil Gauge

    Directory of Open Access Journals (Sweden)

    Bashir A. Tahir

    2005-01-01

    Full Text Available Technology such as Fiber Bragg Grating (FBG sensors are widely accepted in almost all industries. FBG are being investigated for their applicability in other markets such as smart structures. Fiber optic sensors can also be used in many different applications. Fiber optic sensors are available in several types; among them, the Bragg grating sensor is being studied in this research. For this research work, the main focus was the use of fiber Bragg grating sensors for measuring strain. The key objective of this research; to determine the functionality of fiber Bragg grating sensors compared to that of conventional foil gauges. Fiber Bragg grating sensors were chosen for this research because they have a high potential for various uses in the monitoring of smart structures. The major incentives for this type of research are the current deterioration of civil structures in west Malaysia. The laboratory tests are being reported in this research work including tests of steel straps and an aluminum test specimen. In all the tests, strain was measured using the fiber Bragg grating sensors and compared to values from a conventional foil gauge. The results are being discussed in details. It was inferred that the use of fiber optic technology for the monitoring of civil structures is very promising and the future is sure to bring further advancements and improvements.

  9. Heavy ion induced damage to plasmid DNA: plateau region vs. spread out Bragg-peak

    Science.gov (United States)

    Dang, H. M.; van Goethem, M. J.; van der Graaf, E. R.; Brandenburg, S.; Hoekstra, R.; Schlathölter, T.

    2011-08-01

    We have investigated the damage of synthetic plasmid pBR322 DNA in dilute aqueous solutions induced by fast carbon ions. The relative contribution of indirect damage and direct damage to the DNA itself is expected to vary with linear energy transfer along the ion track, with the direct damage contribution increasing towards the Bragg peak. Therefore, 12C ions at the spread-out Bragg peak (dose averaged LET∞ = 189 ± 15 keV/ μm) and in the plateau region of the Bragg curve (LET = 40 keV/ μm) were employed and the radical scavenger concentration in the plasmid solution was varied to quantify the indirect effect. In order to minimize the influence of 12C break-up fragments, a relatively low initial energy of 90 MeV/nucleon was employed for the carbon ions. DNA damage has been quantified by subsequent electrophoresis on agarose gels. We find that strand breaks due to both indirect and direct effects are systematically higher in the plateau region as compared to the Bragg peak region with the difference being smallest at high scavenging capacities. In view of the fact that the relative biological effectiveness for many biological endpoints is maximum at the Bragg peak our findings imply that DNA damage at the Bragg peak is qualitatively most severe.

  10. Development of Bragg Gratings as Shear Stress Monitors in Aerodynamic >Facilities

    Science.gov (United States)

    Parmar, Devandra S.

    1998-04-01

    Two Bragg gratings centered at 1289.565 nm and 1299.432 nm were co-written in the core of a 9/125 telecommunications fiber doped with 10 weight percent germanium. The fiber was mounted in a 126 deep groove, with a 127 diameter semicircular bottom, etched in a flat metal plate used as the test model. A 1 thick epoxy layer bonded the fiber to the metal plate. A thermocouple was also attached to the metal plate in the vicinity of the Bragg fiber. The metal plate was next mounted in the test section of a subsonic wind tunnel. A skin friction balance was also mounted on the wall of the test section. As the wind speed in the tunnel was increased from 0 to 90 m/sec, reflected Bragg wavelengths and the fiber temperatures were recorded continuously. At a windspeed of 38.89 m/sec, the tunnel flow experienced a fan-induced turbulence registered by the skin friction balance as well as the Bragg signals. This commonality of the turbulence signal registration provided a unique calibration datum for the modulus of rigidity of the Bragg fiber assembly. This value of h has been used to calculate the values of shear stress at various tunnel speeds on the basis of Bragg wavelength changes at those speeds.

  11. Heavy ion induced damage to plasmid DNA: plateau region vs. spread out Bragg-peak

    Energy Technology Data Exchange (ETDEWEB)

    Dang, H.M.; Van Goethem, M.J.; Van der Graaf, E.R.; Brandenburg, S.; Hoekstra, R.; Schlatholtera, T. [KVI University of Groningen, Zernikelaan 25, 9747AA Groningen (Netherlands)

    2011-08-15

    We have investigated the damage of synthetic plasmid pBR322 DNA in dilute aqueous solutions induced by fast carbon ions. The relative contribution of indirect damage and direct damage to the DNA itself is expected to vary with linear energy transfer along the ion track, with the direct damage contribution increasing towards the Bragg peak. Therefore, {sup 12}C ions at the spread-out Bragg peak (dose averaged LET{sub {infinity} }= (189 {+-} 15) keV/{mu}m) and in the plateau region of the Bragg curve (LET = 40 keV/{mu}m) were employed and the radical scavenger concentration in the plasmid solution was varied to quantify the indirect effect. In order to minimize the influence of {sup 12}C break-up fragments, a relatively low initial energy of 90 MeV/nucleon was employed for the carbon ions. DNA damage has been quantified by subsequent electrophoresis on agarose gels. We find that strand breaks due to both indirect and direct effects are systematically higher in the plateau region as compared to the Bragg peak region with the difference being smallest at high scavenging capacities. In view of the fact that the relative biological effectiveness for many biological endpoints is maximum at the Bragg peak our findings imply that DNA damage at the Bragg peak is qualitatively most severe. (authors)

  12. Heavy ion induced damage to plasmid DNA: plateau region vs. spread out Bragg-peak

    International Nuclear Information System (INIS)

    We have investigated the damage of synthetic plasmid pBR322 DNA in dilute aqueous solutions induced by fast carbon ions. The relative contribution of indirect damage and direct damage to the DNA itself is expected to vary with linear energy transfer along the ion track, with the direct damage contribution increasing towards the Bragg peak. Therefore, 12C ions at the spread-out Bragg peak (dose averaged LET∞ = (189 ± 15) keV/μm) and in the plateau region of the Bragg curve (LET = 40 keV/μm) were employed and the radical scavenger concentration in the plasmid solution was varied to quantify the indirect effect. In order to minimize the influence of 12C break-up fragments, a relatively low initial energy of 90 MeV/nucleon was employed for the carbon ions. DNA damage has been quantified by subsequent electrophoresis on agarose gels. We find that strand breaks due to both indirect and direct effects are systematically higher in the plateau region as compared to the Bragg peak region with the difference being smallest at high scavenging capacities. In view of the fact that the relative biological effectiveness for many biological endpoints is maximum at the Bragg peak our findings imply that DNA damage at the Bragg peak is qualitatively most severe. (authors)

  13. Circularly symmetric light scattering from nanoplasmonic spirals.

    Science.gov (United States)

    Trevino, Jacob; Cao, Hui; Dal Negro, Luca

    2011-05-11

    In this paper, we combine experimental dark-field imaging, scattering, and fluorescence spectroscopy with rigorous electrodynamics calculations in order to investigate light scattering from planar arrays of Au nanoparticles arranged in aperiodic spirals with diffuse, circularly symmetric Fourier space. In particular, by studying the three main types of Vogel's spirals fabricated by electron-beam lithography on quartz substrates, we demonstrate polarization-insensitive planar light diffraction in the visible spectral range. Moreover, by combining dark-field imaging with analytical multiparticle calculations in the framework of the generalized Mie theory, we show that plasmonic spirals support distinctive structural resonances with circular symmetry carrying orbital angular momentum. The engineering of light scattering phenomena in deterministic structures with circular Fourier space provides a novel strategy for the realization of optical devices that fully leverage on enhanced, polarization-insensitive light-matter coupling over planar surfaces, such as thin-film plasmonic solar cells, plasmonic polarization devices, and optical biosensors. PMID:21466155

  14. Analytical Optimization of Piezoelectric Circular Diaphragm Generator

    Directory of Open Access Journals (Sweden)

    S. Mohammadi

    2013-01-01

    Full Text Available This paper presents an analytical study of the piezoelectric circular diaphragm microgenerator using strain energy method. Piezoelectrics are the intelligent materials that can be used as transducer to convert mechanical energy into electrical energy and vice versa. The aim of this paper is to optimize produced electrical energy from mechanical pressure. Therefore, the circular metal plate equipped with piezoelectric circular patch has been considered with simply and clamped supports. A comprehensive modeling, parametrical study and the effect of the boundary conditions on the performance of the microgenerator have been investigated. The system is under variable pressure from an oscillating pressure source. Results are presented for PZT and PMN-PT piezoelectric materials with steel and aluminum substrates. An optimal value for the radius and thickness of the piezoelectric layer with a special support condition has been obtained.

  15. Charged Particle Optics in Circular Higgs Factory

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yunhai [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-02-26

    Similar to a super B-factory, a circular Higgs factory will require strong focusing systems near the interaction points and a low-emittance lattice in arcs to achieve a factory luminosity. At electron beam energy of 120 GeV, beamstrahlung effects during the collision pose an additional challenge to the collider design. In particular, a large momentum acceptance at 2 percent level is necessary to retain an adequate beam lifetime. This turns out to be the most challenging aspect in the design of circular Higgs factory. In this paper, an example will be provided to illustrate the beam dynamics in circular Higgs factory, emphasizing on the chromatic optics. Basic optical modules and advanced analysis will be presented. Most important, we will show that 2% momentum aperture is achievable

  16. Circular object recognition based on shape parameters

    Institute of Scientific and Technical Information of China (English)

    Chen Aijun; Li Jinzong; Zhu Bing

    2007-01-01

    To recognize circular objects rapidly in satellite remote sensing imagery, an approach using their geometry properties is presented.The original image is segmented to be a binary one by one dimension maximum entropy threshold algorithm and the binary image is labeled with an algorithm based on recursion technique.Then, shape parameters of all labeled regions are calculated and those regions with shape parameters satisfying certain conditions are recognized as circular objects.The algorithm is described in detail, and comparison experiments with the randomized Hough transformation (RHT) are also provided.The experimental results on synthetic images and real images show that the proposed method has the merits of fast recognition rate, high recognition efficiency and the ability of anti-noise and anti-jamming.In addition, the method performs well when some circular objects are little deformed and partly misshapen.

  17. Chaotic Motion of Corrugated Circular Plates

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large deflection theory of thin anisotropic circular plates was used to analyze the bifurcation behavior and chaotic phenomena of a corrugated thin circular plate with combined transverse periodic excitation and an in-plane static boundary load. The nonlinear dynamic equation for the corrugated plate was derived by employing Galerkin's technique. The critical conditions for occurrence of the homoclinic and subharmonic bifurcations as well as chaos were studied theoretically using the Melnikov function method. The chaotic motion was also simulated numerically using Maple, with the Poincaré map and phase curve used to evaluate when chaotic motion appears. The results indicate some chaotic motion in the corrugated plate. The method is directly applicable to chaotic analysis of an isotropic circular plate.

  18. El Nino phenomenon, effects on the tree of coffee

    International Nuclear Information System (INIS)

    El Nino phenomenon is manifested in the coffee by a deficiency of water in the plant, that which affects its normal development in its fruits; the author describes other alterations that affect the plants of coffee due to El Nino phenomenon

  19. The Grey Nomad Phenomenon: Changing the Script of Aging

    Science.gov (United States)

    Onyx, Jenny; Leonard, Rosemary

    2007-01-01

    This article explores a relatively new and little understood phenomenon, that of the Australian Grey Nomads. Every year increasing numbers of older Australians take to the road. This article explores the phenomenon both empirically and theoretically. A grounded approach is used by which the experience is explored from an ethnographic account…

  20. Autoresuscitation: A Case and Discussion of the Lazarus Phenomenon

    Directory of Open Access Journals (Sweden)

    Kjartan Eskjaer Hannig

    2015-01-01

    Full Text Available Lazarus phenomenon or autoresuscitation is a very rare condition defined as delayed unassisted return of spontaneous circulation after cessation of cardiopulmonary resuscitation. Based on a case with a 67-year-old male who came back to life after discontinuation of cardiopulmonary resuscitation, we discuss the background and possible countermeasures related to the Lazarus phenomenon.

  1. Fluorescence: An Interdisciplinary Phenomenon for Different Education Levels

    Science.gov (United States)

    García, J. A.; Moreno, J. M.; Perales, F. J.; Romero, J.; Sánchez, P.; Gómez-Robledo, L.

    2012-01-01

    This paper shows the scientific foundations of a natural phenomenon of undoubted interest and applicability in our day, fluorescence, and its possibilities for teaching at three educational levels: primary, secondary and university. It begins by describing the nature of the phenomenon and continues by explaining how we work with students of the…

  2. Laurent phenomenon algebras and the discrete BKP equation

    Science.gov (United States)

    Okubo, Naoto

    2016-09-01

    We construct the Laurent phenomenon algebras the cluster variables of which satisfy the discrete BKP equation, the discrete Sawada–Kotera equation and other difference equations obtained by its reduction. These Laurent phenomenon algebras are constructed from seeds with a generalization of mutation-period property. We show that a reduction of a seed corresponds to a reduction of a difference equation.

  3. Autoresuscitation: A Case and Discussion of the Lazarus Phenomenon

    OpenAIRE

    Kjartan Eskjaer Hannig; Rasmus Wulff Hauritz; Erik Lerkevang Grove

    2015-01-01

    Lazarus phenomenon or autoresuscitation is a very rare condition defined as delayed unassisted return of spontaneous circulation after cessation of cardiopulmonary resuscitation. Based on a case with a 67-year-old male who came back to life after discontinuation of cardiopulmonary resuscitation, we discuss the background and possible countermeasures related to the Lazarus phenomenon.

  4. Palladium coated fibre Bragg grating based hydrogen sensor

    International Nuclear Information System (INIS)

    Detection of steam generator leaks in fast nuclear reactors is carried out by monitoring hydrogen in argon cover-gas. Hydrogen released during sodium cleaning of fast reactor components is required to be monitored. Hydrogen sensors with good sensitivity, stability and response time are required for all the above applications. We report a new type of hydrogen sensor with a Fibre Bragg Grating (FBG) coated with palladium thin film which is used to detect the leak of hydrogen gas in the Steam Generator (SG) module of the Fast Breeder Reactor (FBR). If water leaks into sodium, it results in sodium-water reaction. In this reaction hydrogen and sodium hydroxide are formed. Due to the explosive risk of hydrogen system, hydrogen sensors are of great interest in this case. It is known that hydrogen forms an explosive mixture with air once its concentration exceeds beyond the explosion limit of four percent. The advantages of FBG based hydrogen sensor over the other hydrogen sensors are its inherent property of safety from sparking, immunity to ambient electromagnetic interference. The sensing mechanism in this device is based on mechanical strain that is induced in the palladium coating when it absorbs hydrogen. This process physically stretches the grating and causes the grating period and grating's refractive index, to change. The Bragg wavelength shift is directly proportional to the strain induced and can be directly related to the percentage of hydrogen exposure. The online monitoring of palladium thin film coating on FBG is carried out and recorded the wavelength change and strain induced on the FBG. A hydrogen sensor set up have been fabricated which consists of SS vessel of capacity 10 litres, provided with pressure gauge, Argon filling line with a valve, Hydrogen injection line with flange, a vent line with valve and Hydrogen sensor fixing point. The Palladium coated FBG based Hydrogen sensor is tested in this experimental facility in the exposure of hydrogen in

  5. Domain structure of circular and ring magnets

    International Nuclear Information System (INIS)

    We present the results of a study of the domain structure and the magnetization reversal processes in arrays of circular and ring magnets, obtained by magnetic force microscopy and magnetization measurements. The particles, with outer diameter 0.55 and 2.2 μm, were made of Permalloy films of thickness 24 and 66 nm. In the circular elements two domain configurations were observed: a vortex structure with perpendicular magnetization at the core and a 'bud' state. In the ring elements the domain structure was found to depend on the ring width: a flux closed state was formed in wide rings and the 'onion' state was observed in narrow rings

  6. Circular economy in China and recommendations

    Institute of Scientific and Technical Information of China (English)

    Zhou Hongchun

    2006-01-01

    @@ It is an overall, urgent and long-term strategic task for China to vigorously develop the circular economy and build a resource-saving and environmental-friendly society. China is now at the accelerating stage of industrialization and urbanization.Lower per-capita resource amount and tendency of environmental deterioration has not been fundamentally averted. Therefore a circular economy development is an inevitable choice to realize the goal of building a well-off society, ensure sustainable development of national economy, and coordinate the relationship between mankind and nature.

  7. Circularly polarized U-Slot antenna

    OpenAIRE

    Tong, K. F.; Wong, T P

    2007-01-01

    Circularly polarized single-layer U-slot microstrip patch antenna has been proposed. The suggested asymmetrical U-slot can generate the two orthogonal modes for circular polarization without chamfering any corner of the probe-fed square patch microstrip antenna. A parametric study has been carried out to investigate the effects caused by different arm lengths of the U-slot. The thickness of the foam substrate is about 8.5% of the wavelength at the operating frequency. The 3 dB axial ratio ban...

  8. Broadband Suspended Microstrip Antenna For Circular Polarization

    OpenAIRE

    Kasabegoudar, VG; Vinoy, KJ

    2009-01-01

    In this paper we propose a circularly polarized (CP) microstrip antenna on a suspended substrate with a coplanar capacitive feed and a slot within the rectangular patch. The antenna has an axial ratio bandwidth (< 3 dB) of 7.1%. The proposed antenna exhibits a much higher impedance bandwidth of about 49% (S11 < -10 dB) and also yields return loss better than -15 dB in the useful range of circular polarization. Measured characteristics of the antenna are in good agreement with the simulated re...

  9. Free vibrations of circular cylindrical shells

    CERN Document Server

    Armenàkas, Anthony E; Herrmann, George

    2013-01-01

    Free Vibrations of Circular Cylindrical Shells deals with thin-walled structures that undergo dynamic loads application, thereby resulting in some vibrations. Part I discusses the treatment of problems associated with the propagation of plane harmonic waves in a hollow circular cylinder. In such search for solutions, the text employs the framework of the three-dimensional theory of elasticity. The text explains the use of tables of natural frequencies and graphs of representative mode shapes of harmonic elastic waves bounding in an infinitely long isotropic hollow cylinder. The tables are

  10. Circularly Polarized Luminescence from Simple Organic Molecules.

    Science.gov (United States)

    Sánchez-Carnerero, Esther M; Agarrabeitia, Antonia R; Moreno, Florencio; Maroto, Beatriz L; Muller, Gilles; Ortiz, María J; de la Moya, Santiago

    2015-09-21

    This article aims to show the identity of "circularly polarized luminescent active simple organic molecules" as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented. PMID:26136234

  11. Rectangular-to-circular groove waveguide junction

    Institute of Scientific and Technical Information of China (English)

    CUI; Licheng; (崔立成); YANG; Hongsheng; (杨鸿生)

    2003-01-01

    Mode matching method is used to analyze the scattering characteristics of the rectangular-to-circular groove waveguide junction. Firstly, the scattering matrix equation is obtained by matching the electromagnetic fields at the boundary of the junction. The scattering coefficients can be obtained from the equation. Secondly the scattering characteristics of the iris with rectangular window positioned in circular groove waveguide are briefly analyzed. Thirdly, the convergent problem is discussed and the numerical results are given. At last experiment is made and good agreement is found between the calculated results and the measured results.

  12. Circular depolarization ratios of single water droplets and finite ice circular cylinders: a modeling study

    Directory of Open Access Journals (Sweden)

    M. Nicolet

    2011-11-01

    Full Text Available Computations of the phase matrix elements for single water droplets and ice crystals in fixed orientations are presented to determine if circular depolarization δ±C is more accurate than linear depolarization for phase discrimination. T-matrix simulations were performed to calculate right-handed and left-handed circular depolarization ratios δ+C, respectively δ−C and to compare them with linear ones. Ice crystals are assumed to have a circular cylindrical shape where their surface-equivalent diameters range up to 5 μm. The circular depolarization ratios of ice particles were generally higher than linear depolarization and depended mostly on the particle orientation as well as their sizes. The fraction of non-detectable ice crystals (δ < 0.05 was smaller considering a circular polarized light source, reaching 4.5%. However, water droplets also depolarized light circularly for scattering angles smaller than 179° and size parameters smaller than 6 at side- and backscattering regions. Differentiation between ice crystals and water droplets might be difficult for experiments performing at backscattering angles which deviate from 180° unlike lidar applications. If the absence of the liquid phase is confirmed, the use of circular depolarization in single particle detection is more sensitive and less affected by particle orientation.

  13. Accuracy of needle position measurements using fiber Bragg gratings.

    Science.gov (United States)

    Henken, Kirsten; Van Gerwen, Dennis; Dankelman, Jenny; Van Den Dobbelsteen, John

    2012-11-01

    Accurate placement of the needle tip is essential in percutaneous therapies such as radiofrequency ablation (RFA) of liver tumors. Use of a robotic system for navigating the needle could improve the targeting accuracy. Real-time information on the needle tip position is needed, since a needle deflects during insertion in tissue. Needle shape can be reconstructed based on strain measurements within the needle. In the current experiment we determined the accuracy with which the needle tip position can be derived from strain measurements using Fiber Bragg Gratings (FBGs). Three glass fibers equipped with two FBGs each were incorporated in a needle. The needle was clamped at one end and deformed by applying static radial displacements at one or two locations. The FBG output was used for offline estimation of the needle shape and tip position. During deflections of the needle tip up to 12.5 mm, the tip position was estimated with a mean accuracy of 0.89 mm (std 0.42 mm). Adding a second deflection resulted in an error of 1.32 mm (std 0.48 mm). This accuracy is appropriate for applications such as RFA of liver tumors. The results further show that the accuracy can be improved by optimizing the placement of FBGs. PMID:22455615

  14. Investigation on Thermal-Induced Decay of Fiber Bragg Grating

    Science.gov (United States)

    Zhang, Peng; Ding, Pinyi; Liu, Li

    2015-06-01

    A fiber Bragg grating (FBG), with advantages such as high anti-interference ability, a simple structure, and multiplexing, is widely used as a core component in numerous applications to monitor adverse environments of high temperature and air pressure. When FBGs are exposed to these extreme conditions, especially high temperature, performance decay may occur, bringing serious impact on the stability and reliability of the instruments. Therefore, it is necessary to make a detailed analysis on the mechanism of the thermal-induced decay of a FBG. One commonly used theory is proposed by Erdogn, which is based on a power function and aging curve method. However, these empirical equations are limited in application because only one single type of FBG can be analyzed this way. This paper focuses on the mechanism of a FBG, and presents a detailed analysis on the theory of the thermal-induced decay of a FBG using the electron dipole mode. Theoretical relationships between reflectivity and time or temperature were obtained, and a corresponding thermal-induced decay testing system was designed. The experimental and theoretical reflectivity decline under different temperatures of and are plotted, and the curves of reduction derived from the theoretical model fit the experimental data well. Thus, this model can be applied to predict the performance decay of FBGs at high temperature.

  15. Nuclear Bragg diffraction of synchrotron x-rays

    International Nuclear Information System (INIS)

    In the last few years several groups have successfully carried out experiments involving the excitation of nuclear resonances using synchrotron radiation. All the experiments so far have used 57Fe as the resonant nucleus. The extremely narrow width of the 14.4 keV resonance in 57Fe makes these experiments very difficult at even the highest-brightness synchrotron beam lines currently available, so much effort is being devoted toward improvements in equipment and techniques. The general aim of this work is to use resonant scattering to produce high-flux beams of extremely monochromatic radiation, which can then be used as source beams for a variety of experiments. This talk, however, will stress the kinds of physics questions that can be answered using broad-band synchrotron radiation to induce resonant nuclear diffraction in perfect crystal samples. Experiments of this type are being carried out today, albeit with difficulty, using present synchrotron sources. They will become technically easy when advanced sources such as the APS become available, and it is expected that nuclear Bragg diffraction will become a standard technique

  16. Perimeter security alarm system based on fiber Bragg grating

    Science.gov (United States)

    Zhang, Cui; Wang, Lixin

    2010-11-01

    With the development of the society and economy and the improvement of living standards, people need more and more pressing security. Perimeter security alarm system is widely regarded as the first line of defense. A highly sensitive Fiber Bragg grating (FBG) vibration sensor based on the theory of the string vibration, combined with neural network adaptive dynamic programming algorithm for the perimeter security alarm system make the detection intelligently. Intelligent information processing unit identify the true cause of the vibration of the invasion or the natural environment by analyzing the frequency of vibration signals, energy, amplitude and duration. Compared with traditional perimeter security alarm systems, such as infrared perimeter security system and electric fence system, FBG perimeter security alarm system takes outdoor passive structures, free of electromagnetic interference, transmission distance through optical fiber can be as long as 20 km It is able to detect the location of event within short period of time (high-speed response, less than 3 second).This system can locate the fiber cable's breaking sites and alarm automatically if the cable were be cut. And the system can prevent effectively the false alarm from small animals, birds, strong wind, scattering things, snowfalls and vibration of sensor line itself. It can also be integrated into other security systems. This system can be widely used in variety fields such as military bases, nuclear sites, airports, warehouses, prisons, residence community etc. It will be a new force of perimeter security technology.

  17. Fiber Bragg grating sensors for strain monitoring of steelwork

    Science.gov (United States)

    Wang, Tao; He, Dawei; Yang, Fan; Wang, Yongsheng

    2009-11-01

    Over the last few years, fiber Bragg grating (FBG) sensors have attracted a lot of interest and they are being used in various applications. This paper describes the FBG sensors used for strain monitoring of bogie and other steelworks. FBG sensors and resistance strain gauges are set on different position of steel girder, and weight is loaded on the steel girder. Strain value of the steel girder can be caught by two kinds of sensors when weight loaded is changed. Result of experiment shows that strain value obtained by resistance strain gauges and FBG sensor is coinciding. There is a linear correlation between value of strain and the weight loaded on the steel girder. FBG sensors with different encapsulations are set on bogie by acrylic plastic materials in order to monitor its dynamic strains. When sinusoidal load with its frequency from 0.15Hz to 2Hz was set on the bogie, FBG sensor system with data sampling rate of 20Hz were used to monitoring the dynamic strains. Strain data caught by FBG sensor system can offer accurate description of dynamic strain, and value of strain provided by FBG sensor suits theoretical values well. The experimental observations show that FBG sensors can be set on steelworks easily, and can monitor both static strain and dynamic strains well.

  18. Integrated waveguide Bragg gratings for microwave photonics signal processing.

    Science.gov (United States)

    Burla, Maurizio; Cortés, Luis Romero; Li, Ming; Wang, Xu; Chrostowski, Lukas; Azaña, José

    2013-10-21

    Integrated Microwave photonics (IMWP) signal processing using Photonic Integrated Circuits (PICs) has attracted a great deal of attention in recent years as an enabling technology for a number of functionalities not attainable by purely microwave solutions. In this context, integrated waveguide Bragg grating (WBG) devices constitute a particularly attractive approach thanks to their compactness and flexibility in producing arbitrarily defined amplitude and phase responses, by directly acting on coupling coefficient and perturbations of the grating profile. In this article, we review recent advances in the field of integrated WBGs applied to MWP, analyzing the advantages leveraged by an integrated realization. We provide a perspective on the exciting possibilities offered by the silicon photonics platform in the field of MWP, potentially enabling integration of highly-complex active and passive functionalities with high yield on a single chip, with a particular focus on the use of WBGs as basic building blocks for linear filtering operations. We demonstrate the versatility of WBG-based devices by proposing and experimentally demonstrating a novel, continuously-tunable, integrated true-time-delay (TTD) line based on a very simple dual phase-shifted WBG (DPS-WBG). PMID:24150355

  19. Opto-acoustic behavior of coated fiber Bragg gratings.

    Science.gov (United States)

    Moccia, Massimo; Pisco, Marco; Cutolo, Antonello; Galdi, Vincenzo; Bevilacqua, Pierantonio; Cusano, Andrea

    2011-09-26

    In this paper, we present the study of the acousto-optic behavior of underwater-acoustic sensors constituted by fiber Bragg gratings (FBGs) coated by ring-shaped overlays. Via full-wave numerical simulations, we study the complex opto-acousto-mechanical interaction among an incident acoustic wave traveling in water, the optical fiber surrounded by the ring shaped coating, and the FBG inscribed the fiber, focusing on the frequency range 0.5-30 kHz of interest for SONAR applications. Our results fully characterize the mechanical behavior of an acoustically driven coated FBG, and highlight the key role played by the coating in enhancing significantly its sensitivity by comparison with a standard uncoated configuration. Furthermore, the hydrophone sensitivity spectrum exhibits characteristic resonances, which strongly improve the sensitivity with respect to its background (i.e., away from resonances) level. Via a three-dimensional modal analysis, we verify that the composite cylindrical structure of the sensor acts as an acoustic resonator tuned at the frequencies of its longitudinal vibration modes. In order to evaluate the sensor performance, we also carry out a comprehensive parametric analysis by varying the geometrical and mechanical properties of the coating, whose results also provide a useful design tool for performance optimization and/or tailoring for specific SONAR applications. Finally, a preliminary validation of the proposed numerical analysis has been carried out through experimental data obtained using polymeric coated FBGs sensors revealing a good agreement and prediction capability. PMID:21996827

  20. Photonic hydrophones based on coated fiber Bragg gratings

    International Nuclear Information System (INIS)

    The development of underwater acoustic sensors with performances competitive with conventional piezoelectric hydrophones would overcome intrinsic limitations related to the piezoceramic technology. Optical fiber technology represents a valid platform to implement acoustic sensors for underwater scenarios. Here we report on recent numerical and experimental results obtained with photonic hydrophones based on fiber-Bragg-grating (FBG) with ring shaped coatings. Our numerical results fully characterize the opto-acoustic response of the optical hydrophone, and highlight the key role played by the coating in enhancing significantly its sensitivity by comparison with a standard uncoated configuration. Furthermore, the analysis reveals that the hydrophone sensitivity spectrum exhibits characteristic resonances, which strongly improve the sensitivity with respect to its background level. Our experimental results confirmed the expected resonant behavior of such devices and are in good agreement with the numerical predictions. Optical hydrophones based on coated FBG exhibited an excellent capability to detect acoustic waves in the acoustic frequency range, with extremely high sensitivities. By comparison with bare FBGs, sensitivity enhancements of up to three orders of magnitude were found, demonstrating the effectiveness of polymeric coatings in tailoring the acoustic response of FBG-based hydrophones.