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Sample records for body taper conspire

  1. Controlled quantum dialogue robust against conspiring users

    Science.gov (United States)

    Kao, Shih-Hung; Hwang, Tzonelih

    2016-07-01

    This paper explores a new security problem in controlled quantum dialogue (CQD) protocols, where the communicants may try to conspire to communicate without the controller's permission. According to our survey, all the previous CQD protocols suffer from this attack. In order to resolve this problem, we also present an improvement protocol. The security analyses show that the improved scheme is secure under this and other well-known attacks.

  2. Tapered structure construction

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Eric D.; Takata, Rosalind K.; Slocum, Alexander H.; Nayfeh, Samir A.

    2016-04-05

    Feeding stock used to form a tapered structure into a curving device such that each point on the stock undergoes rotational motion about a peak location of the tapered structure; and the stock meets a predecessor portion of stock along one or more adjacent edges.

  3. Taper Hip Prosthesis

    Medline Plus

    Full Text Available ... L Taper Hip Prosthesis with Modular Neck Kinectiv® Technology March 12, 2009 7:00 PM EDT Welcome ... hopefully you will see the benefits and the advantages of the new Zimmer Kinectiv System. Thank you. ...

  4. Taper Hip Prosthesis

    Medline Plus

    Full Text Available ... We'll see if we can use a large curved retractor just posterior to the acetabulum. I ... old gentleman. Okay. So you're using a large head with very slim tapered head and neck ...

  5. Taper Hip Prosthesis

    Medline Plus

    Full Text Available ... I like this because it presents a nice, flat, broad base to retract the gluteus medius. Nice ... up of the component? It’s a bi-taper design, which is proximally plasma sprayed. The very nice ...

  6. Taper Hip Prosthesis

    Medline Plus

    Full Text Available Zimmer M/L Taper Hip Prosthesis with Modular Neck Kinectiv® Technology March 12, 2009 7:00 PM EDT Welcome to this "OR Live" Webcast presentation brought to you by Zimmer. During ...

  7. Taper Hip Prosthesis

    Medline Plus

    Full Text Available Zimmer M/L Taper Hip Prosthesis with Modular Neck Kinectiv® Technology March 12, 2009 7:00 PM EDT Welcome to this "OR Live" Webcast presentation ... an "OR Live" Webcast on the Kinectiv Total Hip System. At this time, let’s join Dr. Maltry ...

  8. Taper Hip Prosthesis

    Medline Plus

    Full Text Available Zimmer M/L Taper Hip Prosthesis with Modular Neck Kinectiv® Technology March 12, 2009 7:00 PM EDT Welcome to this "OR Live" Webcast presentation brought to ... approximately one centimeter to the shoulder of my prosthesis. And then I will simply use the prosthesis ...

  9. Tapered capillary optics

    Science.gov (United States)

    Hirsch, Gregory

    1998-01-01

    A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

  10. Research of Klopfenstein taper UWB monopole antenna

    OpenAIRE

    Wang, Nan-Nan; Qiu, Jinghui; Zhang, Zhi-Feng; Zong, Hua; Ling-Ling, Zhong; Wei-Bo, Deng

    2011-01-01

    The tapered line theory in circuit can be applied to the design of the special-shaped monopole antenna in order to obtain better electrical characteristics. So a novel Klopfenstein taper monopole antenna is proposed. The impedance matching characteristic of the Klopfenstein tapered line is the best, and the Klopfenstein taper monopole antenna is designed based on it. On this basis, the coplanar waveguide-fed planar Klopfenstein taper monopole antennas are designed. The simulation and measurem...

  11. Tapered undulators for SASE FELs

    CERN Document Server

    Fawley, W M; Vinokurov, N A

    2002-01-01

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

  12. The wild tapered block bootstrap

    DEFF Research Database (Denmark)

    Hounyo, Ulrich

    In this paper, a new resampling procedure, called the wild tapered block bootstrap, is introduced as a means of calculating standard errors of estimators and constructing confidence regions for parameters based on dependent heterogeneous data. The method consists in tapering each overlapping block......-of-the-art block-based method in terms of asymptotic accuracy of variance estimation and distribution approximation. For stationary time series, the asymptotic validity, and the favorable bias properties of the new bootstrap method are shown in two important cases: smooth functions of means, and M-estimators. The...... estimator for the sample mean is shown to be robust against heteroskedasticity of the wild tapered block bootstrap. This easy to implement alternative bootstrap method works very well even for moderate sample sizes....

  13. Controlling nanowire emission profile using conical taper

    DEFF Research Database (Denmark)

    Gregersen, Niels; Nielsen, Torben Roland; Mørk, Jesper;

    2008-01-01

    The influence of a conical taper on nanowire light emission is studied. For nanowires with divergent output beams, the introduction of tapers improves the emission profile and increase the collection efficiency of the detection optics.......The influence of a conical taper on nanowire light emission is studied. For nanowires with divergent output beams, the introduction of tapers improves the emission profile and increase the collection efficiency of the detection optics....

  14. Modeling of nonlinear propagation in fiber tapers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2012-01-01

    A full-vectorial nonlinear propagation equation for short pulses in tapered optical fibers is developed. Specific emphasis is placed on the importance of the field normalization convention for the structure of the equations, and the interpretation of the resulting field amplitudes. Different...... numerical schemes for interpolation of fiber parameters along the taper are discussed and tested in numerical simulations on soliton propagation and generation of continuum radiation in short photonic-crystal fiber tapers....

  15. Tapered fibers embedded in silica aerogel.

    Science.gov (United States)

    Xiao, Limin; Grogan, Michael D W; Leon-Saval, Sergio G; Williams, Rhys; England, Richard; Wadsworth, Willam J; Birks, Tim A

    2009-09-15

    We have embedded thin tapered fibers (with diameters down to 1 microm) in silica aerogel with low loss. The aerogel is rigid but behaves refractively like air, protecting the taper without disturbing light propagation along it. This enables a new class of fiber devices exploiting volume evanescent interactions with the aerogel itself or with dopants or gases in the pores. PMID:19756084

  16. A taper-fused microspherical laser source

    OpenAIRE

    Jonathan M. Ward; Féron, Patrice; Nic Chormaic, Síle

    2008-01-01

    We report on the realization of an integrated lasing device consisting of a microsphere optical resonator fused to a tapered optical fiber. A microsphere fabricated from Er: Yb-codoped phosphate glass is heated above its glass transition temperature of 375degC by pumping it at 977 nm with 70 mW via a tapered optical fiber. The onset of thermal stress in the glass at a maximum pumping power results in the sphere melting and fusing to the taper coupler, without inhibition of whispering gallery ...

  17. Tapered fiber based high power random laser.

    Science.gov (United States)

    Zhang, Hanwei; Du, Xueyuan; Zhou, Pu; Wang, Xiaolin; Xu, Xiaojun

    2016-04-18

    We propose a novel high power random fiber laser (RFL) based on tapered fiber. It can overcome the power scaling limitation of RFL while maintaining good beam quality to a certain extent. An output power of 26.5 W has been achieved in a half-open cavity with one kilometer long tapered fiber whose core diameter gradually changes from 8 μm to 20 μm. The steady-state light propagation equations have been modified by taking into account the effective core area to demonstrate the tapered RFL through numerical calculations. The numerical model effectively describes the power characteristics of the tapered fiber based RFL, and both the calculating and experimental results show higher power exporting potential compared with the conventional single mode RFL. PMID:27137338

  18. Vibration Analysis of Hollow Tapered Shaft Rotor

    OpenAIRE

    P. M. G. Bashir Asdaque; Behera, R. K.

    2014-01-01

    Shafts or circular cross-section beams are important parts of rotating systems and their geometries play important role in rotor dynamics. Hollow tapered shaft rotors with uniform thickness and uniform bore are considered. Critical speeds or whirling frequency conditions are computed using transfer matrix method and then the results were compared using finite element method. For particular shaft lengths and rotating speeds, response of the hollow tapered shaft-rotor system is determined for t...

  19. Nanostructured optical fibre tapers and related applications

    OpenAIRE

    Ding, Ming

    2013-01-01

    In the last decade, optical fibre tapers have attracted considerable interest because they offer a variety of enabling properties, including large evanescent fields, flexibility, configurability, high confinement, robustness and compactness. These distinctive features have been exploited in a wealth of applications ranging from telecommunication devices to sensors, from optical manipulation to high-Q resonators. Nanostructures on the optical fibre tapers are very promising since the size of t...

  20. Rotational flow in tapered slab rocket motors

    Science.gov (United States)

    Saad, Tony; Sams, Oliver C.; Majdalani, Joseph

    2006-10-01

    Internal flow modeling is a requisite for obtaining critical parameters in the design and fabrication of modern solid rocket motors. In this work, the analytical formulation of internal flows particular to motors with tapered sidewalls is pursued. The analysis employs the vorticity-streamfunction approach to treat this problem assuming steady, incompressible, inviscid, and nonreactive flow conditions. The resulting solution is rotational following the analyses presented by Culick for a cylindrical motor. In an extension to Culick's work, Clayton has recently managed to incorporate the effect of tapered walls. Here, an approach similar to that of Clayton is applied to a slab motor in which the chamber is modeled as a rectangular channel with tapered sidewalls. The solutions are shown to be reducible, at leading order, to Taylor's inviscid profile in a porous channel. The analysis also captures the generation of vorticity at the surface of the propellant and its transport along the streamlines. It is from the axial pressure gradient that the proper form of the vorticity is ascertained. Regular perturbations are then used to solve the vorticity equation that prescribes the mean flow motion. Subsequently, numerical simulations via a finite volume solver are carried out to gain further confidence in the analytical approximations. In illustrating the effects of the taper on flow conditions, comparisons of total pressure and velocity profiles in tapered and nontapered chambers are entertained. Finally, a comparison with the axisymmetric flow analog is presented.

  1. Turbine airfoil fabricated from tapered extrusions

    Science.gov (United States)

    Marra, John J

    2013-07-16

    An airfoil (30) and fabrication process for turbine blades with cooling channels (26). Tapered tubes (32A-32D) are bonded together in a parallel sequence, forming a leading edge (21), a trailing edge (22), and pressure and suction side walls (23, 24) connected by internal ribs (25). The tapered tubes may be extruded without camber to simplify the extrusion process, then bonded along matching surfaces (34), forming a non-cambered airfoil (28), which may be cambered in a hot forming process and cut (48) to length. The tubes may have tapered walls that are thinner at the blade tip (T1) than at the base (T2), reducing mass. A cap (50) may be attached to the blade tip. A mounting lug (58) may be forged (60) on the airfoil base and then machined, completing the blade for mounting in a turbine rotor disk.

  2. Crystallographic Analysis of Tapering of ADP Crystallites

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, the growth rate of prismatic faces is slower and more sensitive to the additives and impurities for ADP crystals. When the supersaturation is low, the advance of growth steps on prismatic face can be blocked by ethanol or impurities, the crystal morphology is changed from the tetragonal prism to shuttle (i.e., the tapered shape). The tapering formation of ADP crystallites was structurally studied in a novel view.

  3. Tapered photonic crystal fibers for blue-enhanced supercontinuum generation

    DEFF Research Database (Denmark)

    Møller, Uffe; Sørensen, Simon Toft; Larsen, Casper;

    2012-01-01

    Tapering of photonic crystal fibers is an effective way of shifting the blue edge of a supercontinuum spectrum down in the deep-blue. We discuss the optimum taper profile for enhancing the power in the blue edge.......Tapering of photonic crystal fibers is an effective way of shifting the blue edge of a supercontinuum spectrum down in the deep-blue. We discuss the optimum taper profile for enhancing the power in the blue edge....

  4. Nanofocusing in a tapered graphene plasmonic waveguide

    DEFF Research Database (Denmark)

    Dai, Yunyun; Zhu, Xiaolong; Mortensen, N. Asger;

    2015-01-01

    Gated or doped graphene can support plasmons making it a promising plasmonic material in the terahertz regime. Here, we show numerically that in a tapered graphene plasmonic waveguide mid- and far-infrared light can be focused in nanometer scales, far beyond the diffraction limit. The underlying ...

  5. Time series tapering for short data samples

    DEFF Research Database (Denmark)

    Kaimal, J.C.; Kristensen, L.

    We explore the effect of applying tapered windows on atmospheric data to eliminate overestimation inherent in spectra computed from short time series. Some windows are more effective than others in correcting this distortion. The Hamming window gave the best results with experimental data. The Ha...

  6. The avian tectorial membrane: Why is it tapered?

    CERN Document Server

    Iwasa, Kuni H

    2015-01-01

    While the mammalian- and the avian inner ears have well defined tonotopic organizations as well as hair cells specialized for motile and sensing roles, the structural organization of the avian ear is different from its mammalian cochlear counterpart. Presumably this difference stems from the difference in the way motile hair cells function. Short hair cells, whose role is considered analogous to mammalian outer hair cells, presumably depends on their hair bundles, and not motility of their cell body, in providing the motile elements of the cochlear amplifier. This report focuses on the role of the avian tectorial membrane, specifically by addressing the question, "Why is the avian tectorial membrane tapered from the neural to the abneural direction?"

  7. Performance of an elliptically tapered neutron guide

    International Nuclear Information System (INIS)

    Supermirror coated neutron guides are used at all modern neutron sources for transporting neutrons over large distances. In order to reduce the transmission losses due to multiple internal reflection of neutrons, ballistic neutron guides with linear tapering have been proposed and realized. However, these systems suffer from an inhomogeneous illumination of the sample. Moreover, the flux decreases significantly with increasing distance from the exit of the neutron guide. We propose using elliptically tapered guides that provide a more homogeneous phase space at the sample position as well as a focusing at the sample. Moreover, the design of the guide system is simplified because ellipses are simply defined by their long and short axes. In order to prove the concept we have manufactured a doubly focusing guide and investigated its properties with neutrons. The experiments show that the predicted gains using the program package McStas are realized. We discuss several applications of elliptic guides in various fields of neutron physics

  8. Spatially resolved spectroscopy using tapered stripline NMR

    Science.gov (United States)

    Tijssen, Koen C. H.; Bart, Jacob; Tiggelaar, Roald M.; Janssen, J. W. G. (Hans); Kentgens, Arno P. M.; van Bentum, P. Jan M.

    2016-02-01

    Magnetic field B0 gradients are essential in modern Nuclear Magnetic Resonance spectroscopy and imaging. Although RF/B1 gradients can be used to fulfill a similar role, this is not used in common practice because of practical limitations in the design of B1 gradient coils. Here we present a new method to create B1 gradients using stripline RF coils. The conductor-width of a stripline NMR chip and the strength of its radiofrequency field are correlated, so a stripline chip can be tapered to produce any arbitrary shaped B1 field gradient. Here we show the characterization of this tapered stripline configuration and demonstrate three applications: magnetic resonance imaging on samples with nL-μL volumes, reaction monitoring of fast chemical reactions (10-2-101 s) and the compensation of B0 field gradients to obtain high-resolution spectra in inhomogeneous magnetic fields.

  9. Wave breaking in tapered holey fibers

    Institute of Scientific and Technical Information of China (English)

    Shuguang Li; Lei Zhang; Bo Fu; Yi Zheng; Ying Han; Xingtao Zhao

    2011-01-01

    We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers (THFs). The curvature indices of the concave, linear, and convex tapers are 2.0, 1.0, and 0.5, respectively. The central wavelength, located in the normal dispersion regime, is 800 nm. The nonlinear coefficient of the THFs increases from the initial 0.095 m-1· W-1 to the final 0.349 m-l·W-1. Wave breaking accompanied by oscillatory structures occurs near pulse edges, and sidelobes appear in the pulse spectrum. With the increase in propagation distance z, the pulse shape becomes broader and the pulse spectrum flattens. A concave THF is advantageous to the generation of wave breaking and enables easier achievement of super fiat spectra at short lengths.%@@ We numerically study the propagation of 1-ps laser pulse in three tapered holey fibers (THFs).The curvature indices of the concave, linear, and convex tapers are 2.0, 1.0, and 0.5, respectively.The central wavelength, located in the normal dispersion regime, is 800 nm.The nonlinear coefficient of the THFs increases from the initial 0.095 m-1.W-1 to the final 0.349 m-1.W-1.Wave breaking accompanied by oscillatory structures occurs near pulse edges, and sidelobes appear in the pulse spectrum.With the increase in propagation distance z, the pulse shape becomes broader and the pulse spectrum flattens.A concave THF is advantageous to the generation of wave breaking and enables easier achievement of super flat spectra at short lengths.

  10. Supercontinuum noise in tapered photonic crystal fibers

    DEFF Research Database (Denmark)

    Møller, Uffe; Sørensen, Simon Toft; Moselund, Peter Morten;

    Supercontinuum generation (SCG) in highly nonlinear photonic crystal fibers (PCF) has drawn a lot of attention for the last decade. Pumping such PCFs with high-power picosecond laser pulses enables the creation of broadband and intense light. Picosecond SCG is initiated by modulation instability...... and as such contains some noise. It is thus of significant interest to reduce the noise. Here we focus on the noise properties of such supercontinuum (SC) generated in tapered PCFs....

  11. Comparison between 50 W tapered laser arrays and tapered single emitters

    Science.gov (United States)

    Scholz, Christian; Boucke, Konstantin; Poprawe, Reinhart; Keleman, Marc T.; Weber, Jürgen; Mikulla, Michael; Weimann, Günter

    2006-02-01

    During the last few years high power diode laser arrays have become well established for direct material processing due to their high efficiency of more than 50%. But standard broad-area waveguide designs are susceptible to modal instabilities and filamentations resulting in low beam qualities. The beam quality increases by more than a factor of four by using tapered laser arrays, but so far they suffer from lower efficiencies. Therefore tapered lasers are mainly used today as single emitters in external resonator configurations. With increased output power and lifetime, they will be much more attractive for material processing and for pumping of fiber amplifiers. High efficiency tapered mini bars emitting at a wavelength of 980 nm are developed, and in order to qualify the bars, the characteristics of single emitters and mini bars from the same wafer have been compared. The mini bars have a width of 6 mm with 12 emitters. The ridge waveguide tapered lasers consist of a 500 μm long ridge and a 2000 μm long tapered section. The results show very similar behavior of the electro-optical characteristics and the beam quality for single emitters and bars. Due to different junction temperatures, different slope efficiencies were measured: 0.8 W/A for passively cooled mini bars and 1.0 W/A for actively cooled mini-bars and single emitters. The threshold current of 0.7 A per emitter is the same for single emitters and emitter arrays. Output powers of more than 50 W in continuous wave mode for a mini bar with standard packaging demonstrates the increased power of tapered laser bars.

  12. Optimum PCF tapers for blue-enhanced supercontinuum sources

    DEFF Research Database (Denmark)

    Møller, Uffe Visbech; Sørensen, Simon Toft; Larsen, Casper;

    2012-01-01

    Tapering of photonic crystal fibers has proven to be an effective way of blueshifting the dispersive wavelength edge of a supercontinuum spectrum down in the deep-blue. In this article we will review the state-of-the-art in fiber tapers, and discuss the underlying mechanisms of supercontinuum...... generation in tapers. We show, by introducing the concept of a group-acceleration mismatch, that for a given taper length, the downtapering section should be as long as possible to enhance the amount of blueshifted light. We also discuss the noise properties of supercontinuum generation in uniform and...... tapered fibers, and we demonstrate that the intensity noise at the spectral edges of the generated supercontinuum is at a constant level independent on the pump power in both tapered and uniform fibers....

  13. Concept modeling of tapered thin-walled tubes

    Institute of Scientific and Technical Information of China (English)

    Yu-cheng LIU; Michael L.DAY

    2009-01-01

    This paper presents a method to create concept models for the tapered thin-walled tubes using beam elements and spring elements. Developed concept tapered beam models with different taper angles and cross sections are compared with those detailed models through impact analyses. Important crash results are recorded and compared, and the relatively good agreement is achieved between these analyses. Concept modeling steps are illustrated in detail, and a general concept modeling method for such thin-walled tubes is summarized and presented.

  14. Tapered Yagi-Uda Nanoantennas for Broadband Unidirectional Emission

    OpenAIRE

    Staude, Isabelle; Ivan S. Maksymov; Decker, Manuel; Miroshnichenko, Andrey E.; Neshev, Dragomir N.; Jagadish, Chennupati; Kivshar, Yuri S.

    2012-01-01

    We demonstrate experimentally the operation of tapered Yagi-Uda nanoantennas for broadband unidirectional emission enhancement. The measured transmittance spectra show that, in comparison to untapered reference structures, the tapered nanoantennas exhibit distinct wide-band spectral resonances. The performed full-vectorial numerical calculations are in good qualitative agreement with the measured spectra, further revealing how the near-field profiles of the tapered nanoantennas are directly r...

  15. Tapered Yagi-Uda Nanoantennas for Broadband Unidirectional Emission

    CERN Document Server

    Staude, Isabelle; Decker, Manuel; Miroshnichenko, Andrey E; Neshev, Dragomir N; Jagadish, Chennupati; Kivshar, Yuri S

    2012-01-01

    We demonstrate experimentally the operation of tapered Yagi-Uda nanoantennas for broadband unidirectional emission enhancement. The measured transmittance spectra show that, in comparison to untapered reference structures, the tapered nanoantennas exhibit distinct wide-band spectral resonances. The performed full-vectorial numerical calculations are in good qualitative agreement with the measured spectra, further revealing how the near-field profiles of the tapered nanoantennas are directly reflecting their broadband characteristics.

  16. Ultra-low-loss tapered optical fibers with minimal lengths

    CERN Document Server

    Nagai, Ryutaro

    2014-01-01

    We design and fabricate ultra-low-loss tapered optical fibers (TOFs) with minimal lengths. We first optimize variations of the torch scan length using the flame-brush method for fabricating TOFs with taper angles that satisfy the adiabaticity criteria. We accordingly fabricate TOFs with optimal shapes and compare their transmission to TOFs with a constant taper angle and TOFs with an exponential shape. The highest transmission measured for TOFs with an optimal shape is in excess of 99.7 % with a total TOF length of only 23 mm, whereas TOFs with a constant taper angle of 2 mrad reach 99.6 % transmission for a 63 mm TOF length.

  17. Improved Tennis Racquets Have Tapered Strings

    Science.gov (United States)

    Noever, David A.

    1995-01-01

    Design concept for better performing tennis racquet. Essence of concept to taper strings in such way as to shift center of percussion (also called "sweet spot") toward the toe (outer end of racquet, farthest from player's hand). In addition to increasing power on serves, also improves player's control and feel of racquet in player's hand. Racquet less likely to twist in player's hand on off-center shots. Important element of better feel is better absorption of vibrations; especially for players having chronic arm problems. String material nylon, animal gut, or other naturally or artifically spun threads. String can be attached to conventional racquet frame.

  18. Polarization of Tapered Semiconductor Travelling-Wave Amplifiers

    Institute of Scientific and Technical Information of China (English)

    Huang Dexiu; Li Hong

    2001-01-01

    The polarization of a tapered semi-conductor travelling-wave amplifier has been investigated with the transfer matrix method based on convective equation. It is shown that the apparent polarization mode competition exists, and polarization-independent tapered semiconductor travellingwave amplifiers can be obtained through the optimization of amplifier parameters.

  19. Enhanced emission and light control with tapered plasmonic nanoantennas

    OpenAIRE

    Maksymov, Ivan S.; Davoyan, Arthur R.; Kivshar, Yuri S.

    2011-01-01

    We introduce a design of Yagi-Uda plasmonic nanoantennas for enhancing the antenna gain and achieving control over the angular emission of light. We demonstrate that tapering of antenna elements allows to decrease spacing between the antenna elements tenfold also enhancing its emission directivity. We find the optimal tapering angle that provides the maximum directivity enhancement and the minimum end-fire beamwidth.

  20. Wavelength stabilisation during current pulsing of tapered laser

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin

    2009-01-01

    The use of external feedback to stabilise the frequency of a tapered laser during current pulsing is reported. Using this technique more than 20 W of peak power in 60 ns pulses from the tapered laser is obtained and owing to the external feedback, the laser is tunable in the 778-808 nm range. The...

  1. Electromagnetic field tapering using all-dielectric gradient index materials

    Science.gov (United States)

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-01-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes. PMID:27464989

  2. Electromagnetic field tapering using all-dielectric gradient index materials.

    Science.gov (United States)

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-01-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes. PMID:27464989

  3. Electromagnetic field tapering using all-dielectric gradient index materials

    Science.gov (United States)

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  4. High power supercontinuum generation in tapered photonic crystal fibers

    DEFF Research Database (Denmark)

    Møller, Uffe; Sørensen, Simon Toft; Larsen, Casper;

    2012-01-01

    Tapering of photonic crystal fibers has proven to be an effective way of blueshifting the dispersive wavelength edge of a supercontinuum spectrum down in the deep-blue. In this contribution we will discuss the underlying mechanisms of supercontinuum generation in tapers. We show, by introducing the...... concept of a group-acceleration mismatch, that for a given taper length, the downtapering section should be as long as possible to enhance the amount of blueshifted light. We also discuss the noise properties of supercontinuum in uniform and tapered fibers and we demonstrate that the amplitude noise at...... the spectral edges of the generated supercontinuum is at a constant level independent on the pump power in both tapered and uniform fibers....

  5. Configuring the Mesh Size, Side Taper and Wing Depth of Penaeid Trawls to Reduce Environmental Impacts

    Science.gov (United States)

    Broadhurst, Matt K.; Sterling, David J.; Millar, Russell B.

    2014-01-01

    The effects of reducing mesh size while concomitantly varying the side taper and wing depth of a generic penaeid-trawl body were investigated to improve engineering performance and minimize bycatch. Five trawl bodies (with the same codends) were tested across various environmental (e.g. depth and current) and biological (e.g. species and sizes) conditions. The first trawl body comprised 41-mm mesh and represented conventional designs (termed the ‘41 long deep-wing'), while the remaining trawl bodies were made from 32-mm mesh and differed only in their side tapers, and therefore length (i.e. 1N3B or ‘long’ and ∼28o to the tow direction vs 1N5B or ‘short’ and ∼35o) and wing depths (‘deep’–97 T vs ‘shallow’–60 T). There were incremental drag reductions (and therefore fuel savings – by up to 18 and 12% per h and ha trawled) associated with reducing twine area via either modification, and subsequently minimizing otter-board area in attempts to standardize spread. Side taper and wing depth had interactive and varied effects on species selectivity, but compared to the conventional 41 long deep-wing trawl, the 32 short shallow-wing trawl (i.e. the least twine area) reduced the total bycatch by 57% (attributed to more fish swimming forward and escaping). In most cases, all small-meshed trawls also caught more smaller school prawns Metapenaeus macleayi but to decrease this effect it should be possible to increase mesh size slightly, while still maintaining the above engineering benefits and species selectivity. The results support precisely optimizing mesh size as a precursor to any other anterior penaeid-trawl modifications designed to improve environmental performance. PMID:24911786

  6. Numerical study of hub taper angle on podded propeller performance

    International Nuclear Information System (INIS)

    Presently, the majority of podded propulsion systems are of the pulling type, because this type provides better hydrodynamic efficiency than the pushing type. There are several possible explanations for the better overall performance of a puller type podded propulsor. One is related to the difference in hub shape. Puller and pusher propellers have opposite hub taper angles, hence different hub and blade root shape. These differences cause changes in the flow condition and possibly influence the overall performance. The current study focuses on the variation in performance of pusher and puller propellers with the same blade sections, but different hub taper angles. A hyperboloidal low order source doublet steady/unsteady time domain panel method code was modified and used to evaluate effects of hub taper angle on the open water propulsive performance of some fixed pitch screw propellers used in podded propulsion systems. The modified code was first validated against measurements of two model propellers in terms of average propulsive performance and good agreement was found. Major findings include significant effects of hub taper angle on propulsive performance of tapered hub propellers and noticeable effects of hub taper angle on sectional pressure distributions of tapered hub propeller blades. (author)

  7. Numerical study of hub taper angle on podded propeller performance

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.F.; Veitch, B.; Bose, N. [Memorial Univ. of Newfoundland, Faculty of Engineering and Applied Science, St. John' s, Newfoundland (Canada)]. E-mail: Mohammed.Islam@nrc-cnrc.gc.ca; Liu, P. [National Research Council of Canada, Inst. for Ocean Technology (IOT), St. John' s, Newfoundland (Canada)

    2005-07-01

    Presently, the majority of podded propulsion systems are of the pulling type, because this type provides better hydrodynamic efficiency than the pushing type. There are several possible explanations for the better overall performance of a puller type podded propulsor. One is related to the difference in hub shape. Puller and pusher propellers have opposite hub taper angles, hence different hub and blade root shape. These differences cause changes in the flow condition and possibly influence the overall performance. The current study focuses on the variation in performance of pusher and puller propellers with the same blade sections, but different hub taper angles. A hyperboloidal low order source doublet steady/unsteady time domain panel method code was modified and used to evaluate effects of hub taper angle on the open water propulsive performance of some fixed pitch screw propellers used in podded propulsion systems. The modified code was first validated against measurements of two model propellers in terms of average propulsive performance and good agreement was found. Major findings include significant effects of hub taper angle on propulsive performance of tapered hub propellers and noticeable effects of hub taper angle on sectional pressure distributions of tapered hub propeller blades. (author)

  8. Discontinuous Tapered Surface Plasmon Polariton Waveguides with Gap.

    Science.gov (United States)

    Lee, Dong Hun; Lee, Myung-Hyun

    2016-06-01

    We investigate characteristics of discontinuous tapered surface plasmon polariton waveguides with a gap (DTG-SPPWs) to control a guided surface plasmon polariton (SPP) at a telecommunication wavelength of 1.55 μm. The DTG-SPPWs are composed of an input 2 μm-wide and 10 μm-long reverse tapered IMI-W (RT-IMI-W) and a 10 μm-long tapered and output 2 μm-wide IMI-W (T-IMI-W) with the 8 μm-long gap. The width and length of the tapered regions in the RT-IMI-W and the T-IMI-W were varied from 2 to 10 μm and 1 to 8 μm, respectively. Gold is used as the metal in the insulator-metal-insulator waveguides (IMI-Ws). The thickness of the gold strips is fixed with 20 nm. A low-loss polymer is used for the 30 μm-thick upper and lower cladding layers. The coupling losses of the DTG-SPPWs are less than 0.055 dB with an 8 μm-long gap and various taper widths up to 10 μm. The normalized transmissions (NTs) of the DTG-SPPWs are less than about -0.060 dB with various taper widths up to 10 μm. The NTs of the DTG-SPPWs are less than about -0.069 dB with various taper lengths up to 8 μm. The maximum NT of about -0.042 dB was obtained using the 6 μm-wide taper width and the 3 μm-long taper length in the DTG-SPPW. The DTG-SPPWs have potential as a new plasmonic modulation device via control of the guided SPP through interaction with an applied force in the gap. PMID:27427702

  9. Fiber-diffraction Interferometer using Coherent Fiber Optic Taper

    OpenAIRE

    Kihm, Hagyong; Lee, Yun-Woo

    2010-01-01

    We present a fiber-diffraction interferometer using a coherent fiber optic taper for optical testing in an uncontrolled environment. We use a coherent fiber optic taper and a single-mode fiber having thermally-expanded core. Part of the measurement wave coming from a test target is condensed through a fiber optic taper and spatially filtered from a single-mode fiber to be reference wave. Vibration of the cavity between the target and the interferometer probe is common to both reference and me...

  10. Tapered diode laser pumped 946 nm Nd:YAG laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael;

    2009-01-01

    We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....

  11. Study on tapered crossed subwavelength gratings by Fourier modal method

    Science.gov (United States)

    Chen, Xi; Zhong, Yuan; Wang, Qing; Zhang, Ye-Jin; Chen, Liang-Hui

    2010-10-01

    Fourier modal method incorporating staircase approximation is used to study tapered crossed subwavelength gratings in this paper. Three intuitive formulations of eigenvalue functions originating from the prototype are presented, and their convergences are compared through numerical calculation. One of them is found to be suitable in modeling the diffraction efficiency of the circular tapered crossed subwavelength gratings without high absorption, and staircase approximation is further proven valid for non-highly-absorptive tapered gratings. This approach is used to simulate the “moth-eye" antireflection surface on silicon, and the numerical result agrees well with the experimental one.

  12. Study on tapered crossed subwavelength gratings by Fourier modal method

    International Nuclear Information System (INIS)

    Fourier modal method incorporating staircase approximation is used to study tapered crossed subwavelength gratings in this paper. Three intuitive formulations of eigenvalue functions originating from the prototype are presented, and their convergences are compared through numerical calculation. One of them is found to be suitable in modeling the diffraction efficiency of the circular tapered crossed subwavelength gratings without high absorption, and staircase approximation is further proven valid for non-highly-absorptive tapered gratings. This approach is used to simulate the 'moth-eye' antireflection surface on silicon, and the numerical result agrees well with the experimental one. (classical areas of phenomenology)

  13. Simulation of double and single tapered PET collimators

    International Nuclear Information System (INIS)

    This paper reports on interplane data which allows Multi-Slice Positron Emission Tomographs (PET) to reconstruct images of planes between adjacent axial cross sections. The size and shape of the interplane collimators determine the amount of such data which is available for the detectors. Monte Carlo techniques were used to analyze the performance of a new collimator design, a collimator with double tapered geometry, which maximizes interplane data collection by increasing the transaxial crystal area available for photon detection. Simulations were done to compare the behavior of a GBO-Brain scanner when different interplane shaped collimators are used, and for volume imaging systems with tapered collimators. Three collimator shapes were analyzed-cylindrical, tapered and the new collimator with a double tapered geometry. A 9% increase in the efficiency of interplane data collection was observed without significant detriment in any other imaging parameter

  14. Tapered fluorotellurite microstructured fibers for broadband supercontinuum generation.

    Science.gov (United States)

    Wang, Fang; Wang, Kangkang; Yao, Chuanfei; Jia, Zhixu; Wang, Shunbin; Wu, Changfeng; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2016-02-01

    Fluorotellurite microstructured fibers (MFs) based on TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method. Tapered fluorotellurite MFs with varied transition region lengths are prepared by employing an elongation machine. By using a tapered fluorotellurite MF with a transition region length of ∼3.3  cm as the nonlinear medium and a 1560 nm femtosecond fiber laser as the pump source, broadband supercontinuum generation covering from 470 to 2770 nm is obtained. The effects of the transition region length of the tapered fluorotellurite MF on supercontinuum generation are also investigated. Our results show that tapered fluorotellurite MFs are promising nonlinear media for generating broadband supercontinuum light expanding from visible to mid-infrared spectral region. PMID:26907442

  15. Gaussian Filtering with Tapered Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2006-01-01

    We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm......We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm...

  16. Bamboo Taper Effect on Third Point Loading Bending Test

    OpenAIRE

    Naresworo Nugroho; Effendi Tri Bahtiar

    2013-01-01

    Geometrical shape of bamboo usually assumed as tapered hollow pipe. This study proved that the dimensional changes along the bamboo stem significantly affected to its Modulus of Rupture (SR) value which measured from third point loading bending test. Therefore if the bending test applied using third point loading configuration, the SR value should be adjusted by strength ratio of taper (Ct). Ct is theratio between (SR) calculated in the center span and the maximum bending stress along the bam...

  17. Highly efficient hybrid fiber taper coupled microsphere laser

    OpenAIRE

    Ming CAI; Vahala, Kerry

    2001-01-01

    A novel hybrid fiber taper is proposed and demonstrated as the coupler in a microsphere laser system. The pump wave and the laser emission, respectively, are more efficiently coupled to and from the sphere modes with this taper structure. A 980-nm pumped erbium–ytterbium codoped phosphate microsphere laser is demonstrated in the 1550-nm band. As much as 112 µW of single-frequency laser output power was measured, with a differential quantum efficiency of 12%.

  18. A mechanical model of wing and theoretical estimate of taper factor for three gliding birds

    Indian Academy of Sciences (India)

    Moosarreza Shamsyeh Zahedi; Mir Yaseen Ali Khan

    2007-03-01

    We tested a mechanical model of wing, which was constructed using the measurements of wingspan and wing area taken from three species of gliding birds. In this model, we estimated the taper factors of the wings for jackdaw (Corrus monedula), Harris’ hawk (Parabuteo unicinctas) and Lagger falcon (Falco jugger) as 1.8, 1.5 and 1.8, respectively. Likewise, by using the data linear regression and curve estimation method, as well as estimating the taper factors and the angle between the humerus and the body, we calculated the relationship between wingspan, wing area and the speed necessary to meet the aerodynamic requirements of sustained flight. In addition, we calculated the relationship between the speed, wing area and wingspan for a specific angle between the humerus and the body over the range of stall speed to maximum speed of gliding flight. We then compared the results for these three species of gliding birds. These comparisons suggest that the aerodynamic characteristics of Harris’ hawk wings are similar to those of the falcon but different from those of the jackdaw. This paper also presents two simple equations to estimate the minimum angle between the humerus and the body as well as the minimum span ratio of a bird in gliding flight.

  19. Temperature Distribution and Scuffing of Tapered Roller Bearing

    Institute of Scientific and Technical Information of China (English)

    WANG Ailin; WANG Jiugen

    2014-01-01

    In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

  20. Tapered fiber optic sensor for potassium detection in distilled water

    Science.gov (United States)

    Yasin, M.; Pujiyanto, .; Apsari, R.; Tanjung, M.

    2015-01-01

    A simple sensor is proposed and demonstrated using a silica tapered fiber for sensing different concentration of potassium in de-ionized water. The tapered fiber is fabricated using a flame brushing technique to achieve a waist diameter and length of 10 μm and 80 mm, respectively. For a concentration change from 0 to 50 %, the ouput signal of the sensor decreases exponentially from -10.04 dBm to -11.11 dBm with linearity of more than 92%. The increment of potassium concentration increases the refractive index of the solution, which in turn reduces the index difference between core and cladding of the tapered fiber and thus allows more light to be leaked out from the fiber. This new potassium monitoring system provides numerous advantages such as simplicity of design and low cost of production.

  1. Enhanced plasmonic nanofocusing of terahertz waves in tapered graphene multilayers.

    Science.gov (United States)

    Liu, Weiwei; Wang, Bing; Ke, Shaolin; Qin, Chengzhi; Long, Hua; Wang, Kai; Lu, Peixiang

    2016-06-27

    We investigate the plasmonic nanofocusing of terahertz waves in tapered graphene multilayers separated by dielectrics. The nanofocusing effect is significantly enhanced in the graphene multilayer taper compared with that in a single layer graphene taper due to interlayer coupling between surface plasmon polaritons. The results are optimized by choosing an appropriate layer number of graphene and the field amplitude has been enhanced by 620 folds at λ = 50 μm. Additionally, the structure can slow light to a group velocity ~1/2815 of the light speed in vacuum. Our study provides a unique approach to compress terahertz waves into deep subwavelength scale and may find great applications in terahertz nanodevices for imaging, detecting and spectroscopy. PMID:27410629

  2. Gap and channeled plasmons in tapered grooves: a review

    DEFF Research Database (Denmark)

    Smith, C. L. C.; Stenger, Nicolas; Kristensen, Anders;

    2015-01-01

    Tapered metallic grooves have been shown to support plasmons - electromagnetically coupled oscillations of free electrons at metal-dielectric interfaces - across a variety of configurations and V-like profiles. Such plasmons may be divided into two categories: gap-surface plasmons (GSPs) that are......Tapered metallic grooves have been shown to support plasmons - electromagnetically coupled oscillations of free electrons at metal-dielectric interfaces - across a variety of configurations and V-like profiles. Such plasmons may be divided into two categories: gap-surface plasmons (GSPs...... platform to explore the fundamental science of plasmon excitations and their interactions. In this Review, we provide a research status update of plasmons in tapered grooves, starting with a presentation of the theory and important features of GSPs and CPPs, and follow with an overview of the broad range...

  3. Windows tapers effects on the impulse deconvolution filter

    International Nuclear Information System (INIS)

    The aim of the present paper is the study of the effect of window tapers on autocorrelation function, φgg(.), of seismic traces in the design of the important Wiener optimum impulse response filter. Systematic application of window class tapers and truncations, permitted to demonstrate that the resolution of the filter depends on the window type length. As a simple and convenient result, we found that the exponential taper with decaying coefficient β = 30 is one of the best values to start experimenting on processing, with the operator length 2-3 times source pulse length. Due to the non simplicity of the functions involved, the only way to obtain results is through numerical algorithms. (author)

  4. An accurate RLGC circuit model for dual tapered TSV structure

    International Nuclear Information System (INIS)

    A fast RLGC circuit model with analytical expression is proposed for the dual tapered through-silicon via (TSV) structure in three-dimensional integrated circuits under different slope angles at the wide frequency region. By describing the electrical characteristics of the dual tapered TSV structure, the RLGC parameters are extracted based on the numerical integration method. The RLGC model includes metal resistance, metal inductance, substrate resistance, outer inductance with skin effect and eddy effect taken into account. The proposed analytical model is verified to be nearly as accurate as the Q3D extractor but more efficient. (semiconductor integrated circuits)

  5. Tapered amplifier laser with frequency-shifted feedback

    CERN Document Server

    Bayerle, A; Vlaar, P; Pasquiou, B; Schreck, F

    2016-01-01

    We present a frequency-shifted feedback (FSF) laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time. If the FSF laser is seeded by a continuous-wave laser a frequency comb spanning the output spectrum appears in addition to the broadband emission. The laser has an output power of 280mW and a center wavelength of 780nm. The ease and flexibility of use of tapered amplifiers makes our FSF laser attractive for a wide range of applications, especially in metrology.

  6. Bend sensors based on periodically-tapered soft glass fibers

    OpenAIRE

    Wang, Y.; Richardson, D. J.; Brambilla, G; Feng, X.; Petrovich, M.N.; Ding, M.; Song, Z.(Central China Normal University, Wuhan, China)

    2011-01-01

    We demonstrate a technique for tapering periodically an all-solid soft glass fiber consisting of two types of lead silicate glasses by the use of a CO2 laser and investigate the bend sensing applications of the periodically-tapered soft glass fiber. Such a soft glass fiber with periodic microtapers could be used to develop a promising bend sensor with a sensitivity of ?27.75 ?W/m-1 by means of measuring the bend-induced change of light intensity. The proposed bend sensor exhibits a very low m...

  7. FDML swept source at 1060 nm using a tapered amplifier

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang;

    2010-01-01

    We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain medium. These devices feature significantly higher saturation power than conventional semiconductor optical amplifiers and can thus improve the limited output power of swept sources in this...... wavelength range. We demonstrate that a tapered amplifier can be integrated into a fiber-based swept source and allows for high-speed FDML operation. The developed light source operates at a sweep rate of 116kHz with an effective average output power in excess of 30mW. With a total sweep range of 70 nm an...

  8. Perambatan Gelombang Optik pada Grating Sinusoidal dengan Chirp dan Taper

    Directory of Open Access Journals (Sweden)

    Isnani Darti

    2009-11-01

    menggunakan MIL, dipelajari perubahan respon optik pada grating sinusoidal akibat variasi amplitudo modulasi indeks (taper dan variasi frekuensi spasial grating (chirp. Hasil simulasi menunjukkan bahwa taper menyebabkan adanya fenomena penghilangan side-lobe pada spektrum transmitansi. Adanya chirp menyebabkan penghalusan side-lobe pada spektrum transmitansi dengan semakin besar parameter chirp menyebabkan peningkatan transmitansi di sekitar pusat band-gap dari grating homogen. Selain implementasi integrasi numerik (Runge-Kutta, MIL merupakan metode eksak sehingga dapat digunakan untuk mengevaluasi validitas metode yang sering digunakan yaitu Persamaan Moda Tergandeng (PMT. Dari hasil perbandingan dapat disimpulkan bahwa secara umum PMT kurang akurat dalam menganalisis struktur grating sinusoidal baik homogen maupun tak-homogen.

  9. Optimization of Tapered Photonic Crystal Fibers for Blue-Enhanced Supercontinuum Generation

    DEFF Research Database (Denmark)

    Møller, Uffe; Sørensen, Simon Toft; Larsen, Casper;

    2012-01-01

    Tapering of photonic crystal fibers is an effective way of shifting the dispersive wavelength edge of a supercontinuum spectrum down in the deep-blue. We discuss the optimum taper profile for blue-enhanced supercontinuum generation.......Tapering of photonic crystal fibers is an effective way of shifting the dispersive wavelength edge of a supercontinuum spectrum down in the deep-blue. We discuss the optimum taper profile for blue-enhanced supercontinuum generation....

  10. Pseudotumor of Ciliary Body

    Directory of Open Access Journals (Sweden)

    Mary Varghese

    2014-01-01

    Full Text Available Orbital pseudotumor is a benign disease involving the orbital structures. Pseudotumor of the ciliary body is rare. We present a case of a 27-year-old male who presented with gradual visual loss, pain, and redness in his left eye. On examination he was found to have a yellowish white mass at the periphery of anterior chamber in his left eye and ultrasound biomicroscopy (UBM revealed a ciliary body mass in the same eye. He was treated with systemic steroids, which was tapered over a period of 8 weeks. His symptoms improved and the ciliary body mass disappeared with no recurrence over the next 6 months. UBM is an important diagnostic tool for diagnosing ciliary body mass. Early diagnosis and prompt treatment with systemic steroids may help resolve pseudotumor of the ciliary body.

  11. Spontaneous radiation from relativistic electrons in a tapered Apple-II undulator

    International Nuclear Information System (INIS)

    This paper presents most properties of radiation from a tapered Apple-II undulator. The study demonstrates that tapering an Apple-II undulator can broaden the harmonic bandwidth and the performance of polarization is also excellent at the broadened energy range. So Apple-II undulator can be tapered to provide more convenience for energy scan experiment. (authors)

  12. 洛阳市出土元代防奸令牌诠释%A Study of the Anti-conspirator Decree Tablets of the Yuan Dynasty Unearthed from Luoyang City

    Institute of Scientific and Technical Information of China (English)

    蔡美彪

    2003-01-01

    In 2000, five anti-conspirator decree tablets of the Yuan Dynasty were discovered piled up on the site of the eastern city of Sui-Tang Luoyang. The obverse side is cast with Chinese characters: a large “令” in the center and “除伪防奸不许” and “借带违者治罪” on the right and left respectively. The reverse side bears Phagspa, Mongolo-Uighur and Persian scripts. The present paper deciphers the inscriptions and studies the nature and use of the tablets. These findings represent a type of decree tablet the local government issued to archers going on patrol or criminal-catching constables. Their caster may have been the Henan Prefectural Government of the late Yuan Dynasty.

  13. Tapered composite likelihood for spatial max-stable models

    KAUST Repository

    Sang, Huiyan

    2014-05-01

    Spatial extreme value analysis is useful to environmental studies, in which extreme value phenomena are of interest and meaningful spatial patterns can be discerned. Max-stable process models are able to describe such phenomena. This class of models is asymptotically justified to characterize the spatial dependence among extremes. However, likelihood inference is challenging for such models because their corresponding joint likelihood is unavailable and only bivariate or trivariate distributions are known. In this paper, we propose a tapered composite likelihood approach by utilizing lower dimensional marginal likelihoods for inference on parameters of various max-stable process models. We consider a weighting strategy based on a "taper range" to exclude distant pairs or triples. The "optimal taper range" is selected to maximize various measures of the Godambe information associated with the tapered composite likelihood function. This method substantially reduces the computational cost and improves the efficiency over equally weighted composite likelihood estimators. We illustrate its utility with simulation experiments and an analysis of rainfall data in Switzerland.

  14. Pulse propagation in tapered granular chains: An analytic study

    OpenAIRE

    Harbola, Upendra; Rosas, Alexandre; ESPOSITO, massimiliano; Lindenberg, Katja

    2009-01-01

    We study pulse propagation in one-dimensional tapered chains of spherical granules. Analytic results for the pulse velocity and other pulse features are obtained using a binary collision approximation. Comparisons with numerical results show that the binary collision approximation provides quantitatively accurate analytic results for these chains.

  15. Opioid Abstinence Reinforcement Delays Heroin Lapse during Buprenorphine Dose Tapering

    Science.gov (United States)

    Greenwald, Mark K.

    2008-01-01

    A positive reinforcement contingency increased opioid abstinence during outpatient dose tapering (4, 2, then 0 mg/day during Weeks 1 through 3) in non-treatment-seeking heroin-dependent volunteers who had been maintained on buprenorphine (8 mg/day) during an inpatient research protocol. The control group (n = 12) received $4.00 for completing…

  16. Nonlinear Vibration of an Elastically Restrained Tapered Beam

    DEFF Research Database (Denmark)

    Karimpour, S; Ganji, S.S; Barari, Amin; Ibsen, Lars Bo; Domairry, G

    2012-01-01

    This paper presents the analytical simulation of an elastically restrained tapered cantilever beam using the energy balance method (EBM) and the iteration perturbation method (IPM). To assess the accuracy of solutions, we compare the results with the harmonic balance method (HBM). The obtained...

  17. Gaussian Filtering with Tapered Oil-Filled Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Scolari, Lara; Weirich, Johannes;

    2008-01-01

    A tunable Gaussian filter based on a tapered oil-filled photonic crystal fiber is demonstrated. The filter is centered at X=1364nm with a bandwidth (FWHM) of 237nm. Tunability is achieved by changing the temperature of the filter. A shift of 210nm of the central wavelength has been observed by...

  18. Theoretical Analysis and Preparation of Tapered Suspended Core Microstructure Fibers

    Czech Academy of Sciences Publication Activity Database

    Martan, Tomáš; Kaňka, Jiří; Kašík, Ivan; Matějec, Vlastimil

    2009-01-01

    Roč. 3, č. 3 (2009), s. 233-249. ISSN 1559-9612 Institutional research plan: CEZ:AV0Z20670512 Keywords : tapered fibers * optical sensors Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.354, year: 2009

  19. Power dependence of supercontinuum noise in uniform and tapered PCFs

    DEFF Research Database (Denmark)

    Møller, Uffe; Sørensen, Simon Toft; Jakobsen, C.;

    2012-01-01

    We experimentally investigate the noise properties of picosecond supercontinuum spectra generated at different power levels in uniform and tapered photonic crystal fibers. We show that the noise at the spectral edges of the generated supercontinuum is at a constant level independent on the pump...

  20. Coherent multi-octave spanning supercontinuum in tapered sulphide fibres

    DEFF Research Database (Denmark)

    Kubat, Irnis; Mägi, Eric; Hu, Tomonori;

    A novel frequency comb design is proposed based on a newly developed ultrafast 3µm mid-infrared laser in conjunction with micro-taper chalcogenide fibre. The novel design allows for an all-fibre laser source yielding up to three octave coherent supercontinuum. The design is the first step in...

  1. Terahertz field imaging inside tapered parallel plate waveguides

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei; Zhang, Xi-Cheng; Jepsen, Peter Uhd

    We present a non-invasive broadband air photonic method of terahertz field imaging inside a tapered parallel plate waveguide. The method is based on the terahertz-enhanced second harmonic generation of the fundamental laser beam in an external electric field. We also demonstrate the direct...

  2. Taper array in silica glass for beam splitting

    Science.gov (United States)

    Xia, Zehua; Li, Yan; Han, Yanhua; Ge, Meng; Ye, Jingfu; Deng, Duo; Wang, Benyang; Gao, Jianmin; Qu, Shiliang

    2016-03-01

    We proposed taper array in silica glass for beam splitting which was fabricated by water-assisted femtosecond laser direct writing technology and the subsequent heat treatment. We divided the array into many fabricating cells which were executed automatically in sequences as specified by the program that contained the information for the three-dimensional stage movements. Each cell could fabricated a rectangular cylinder. The size and distribution of the rectangular cylinder could be controlled by adjusting the position of the fabricating cells. Then the heat treatment should be used to reshape the rectangular cylinders into taper array. The experimental results show that the taper periodic microstructures in silica glass are uniform and smooth, and the tapers can divide the incident light into beam array. The results demonstrated that the combination of the water-assisted femtosecond laser direct writing technology and the heat treatment is accessible and practical for the high quality micro-optical elements. These micro-optical elements will have potential applications in fluorescence detection and beam splitter.

  3. Ion-exchanged Nd:glass tapered waveguide laser

    OpenAIRE

    Hettrick, S.J.; Mackenzie, J.I.; Wilkinson, J.S.; Tropper, A.C.; Shepherd, D.P.

    2000-01-01

    We report an efficient (>40% slope) and low threshold (~10mW) ion-exchanged Nd:glass tapered waveguide laser with near-diffraction-limited output. This structure is compatible with high-power, broad-stripe, diode pumping.

  4. Vortex Shedding from Tapered Cylinders at high Reynolds Numbers

    DEFF Research Database (Denmark)

    Johansson, Jens; Andersen, Michael Styrk; Christensen, Silas Sverre; Ingólfsson, Karl; Kristensen, Lasse Abildgaard

    2015-01-01

    towers during transportation. Preliminary wind tunnel experiments have been conducted with a tapered cylinder representing these towers. Static tests have been performed up to Re = 7.2x10^5. Dynamic tests at which the system oscillated due to VIV at Re = 1.48x10^5 (Subcritical) and Re = 4.96x10...

  5. Dossier concerning the abuses of Luis de Rosas, governor of New Mexico (1637-1641), his murder in 1641, and the extrajudicial execution of the alleged conspirators in the murder by Alonso Pacheco de Heredia, governor of New Mexico (1642-1644)

    OpenAIRE

    Hidalgo Strolle, Martha; Craddock, Jerry R.; Polt, John H.R.

    2010-01-01

    Edition and translation of a dossier (expediente) concerning the abuses of the governor of New Mexico (1637-1641), his murder in 1641, and the extrajudicial execution of the alleged conspirators in the murder by Alonso Pacheco de Heredia, governor of New Mexico (1642-1644)

  6. Compact and broadband waveguide taper based on partial bandgap photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Jin Hou; Dingshan Gao; Huaming Wu; Zhiping Zhou

    2009-01-01

    Partial bandgap characteristics of parallelogram lattice photonic crystals are proposed to suppress the radiation modes in a compact dielectric waveguide taper so as to obtain high transmittance in a large wavelength range. Band structure of the photonic crystals shows that there exists a partial bandgap. The photonic crystals with partial bandgap are then used as the cladding of a waveguide taper to reduce the radiation loss efficiently. In comparison with the conventional dielectric taper and the complete bandgap photonic crystal taper, the partial bandgap photonic crystal taper has a high transmittance of above 85% with a wide band of 170 nm.

  7. Do Ceramic Femoral Heads Reduce Taper Fretting Corrosion in Hip Arthroplasty? A Retrieval Study

    OpenAIRE

    Kurtz, Steven M.; Kocagöz, Sevi B.; Hanzlik, Josa A.; Underwood, Richard J.; Gilbert, Jeremy L.; MacDonald, Daniel W.; Lee, Gwo-Chin; Mont, Michael A.; Kraay, Matthew J.; Klein, Gregg R.; Parvizi, Javad; Rimnac, Clare M.

    2013-01-01

    Background Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads. Questions/purposes We asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads. Met...

  8. Refractive index sensors based on the fused tapered special multi-mode fiber

    Science.gov (United States)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  9. High-power green light generation by second harmonic generation of single-frequency tapered diode lasers

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Sumpf, Bernd;

    2010-01-01

    We demonstrate the generation of high power (>1.5W) and single-frequency green light by single-pass second harmonic generation of a high power tapered diode laser. The tapered diode laser consists of a DBR grating for wavelength selectivity, a ridge section and a tapered section. The DBR tapered...

  10. Method for Characterization of Material Loss from Modular Head-Stem Taper Surfaces of Hip Replacement Devices

    OpenAIRE

    Racasan, Radu; Bills, Paul J.; Blunt, Liam; Hart, Alister; Skinner, John

    2015-01-01

    Assessment of the head-stem taper junction requires the estimation of material loss from the taper surfaces of both femoral head and stem. This paper describes a method for the measurement and analysis of material loss from the modular taper junction of hip replacements, in particular femoral stem tapers where generally the entire taper surface has been engaged. In such cases no direct unworn datum is readily identifiable to assess material loss. The highly anisotropic topology of some stem d...

  11. X-ray beam compression by tapered waveguides

    International Nuclear Information System (INIS)

    We have fabricated linear tapered waveguide channels filled with air and imbedded in silicon for the hard x-ray regime, using a processing scheme involving e-beam lithography, reactive ion etching, and wafer bonding. Beam compression in such channels is demonstrated by coupling a pre-focused undulator beam into the channels, and recording the exit flux and far-field diffraction patterns. We achieved a compressed beam with a spot size of 16.48 nm (horizontal) × 14.6 nm (vertical) near the waveguide exit plane, as determined from the reconstructed near-field distribution, at an exit flux which is eight times higher than that of an equivalent straight channel. Simulations indicate that this gain could reach three to four orders of magnitude for longer channels with tapering in two directions

  12. Piezoelectric energy harvester having planform-tapered interdigitated beams

    Science.gov (United States)

    Kellogg, Rick A.; Sumali, Hartono

    2011-05-24

    Embodiments of energy harvesters have a plurality of piezoelectric planform-tapered, interdigitated cantilevered beams anchored to a common frame. The plurality of beams can be arranged as two or more sets of beams with each set sharing a common sense mass affixed to their free ends. Each set thus defined being capable of motion independent of any other set of beams. Each beam can comprise a unimorph or bimorph piezoelectric configuration bonded to a conductive or non-conductive supporting layer and provided with electrical contacts to the active piezoelectric elements for collecting strain induced charge (i.e. energy). The beams are planform tapered along the entirety or a portion of their length thereby increasing the effective stress level and power output of each piezoelectric element, and are interdigitated by sets to increase the power output per unit volume of a harvester thus produced.

  13. Spectral narrowing of a 980 nm tapered diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Lucas Leclin, Gaëlle;

    2011-01-01

    in wavelength specific applications and hence, it is vital to stabilize the emission spectrum of these devices. In our experiment, we describe the wavelength narrowing of a 12 element 980 nm tapered diode laser bar using a simple Littman configuration. The tapered laser bar which suffered from a big......High power diode laser bars are interesting in many applications such as solid state laser pumping, material processing, laser trapping, laser cooling and second harmonic generation. Often, the free running laser bars emit a broad spectrum of the order of several nanometres which limit their scope...... smile has been "smile corrected" using individual phase masks for each emitter. The external cavity consists of the laser bar, both fast and slow axis micro collimators, smile correcting phase mask, 6.5x beam expanding lens combination, a 1200 lines/mm reflecting grating with 85% efficiency in the first...

  14. Free-electron lasers with very slow wiggler taper

    Energy Technology Data Exchange (ETDEWEB)

    Bosley, D.L.; Kevorkian, J.

    1990-09-01

    A highly accurate, explicit asymptotic solution of the electron energy and phase is found for a class of free-electron lasers with very long wavelength beams, very low electron energies, and very slow taper of the wiggler field relative to the wiggler period. Dimensionless variables are defined and normalized, and three small parameters which characterize the operation of the FEL are identified. Because of the explicit nature of the solution, our results may be directly used to calculate features such as the escape distance of the electron from the potential well and the effects of the various physical parameters. One important advantage of the very slow wiggler taper is the increased efficiency of the energy transfer from the electron beam to the signal field due to increased bucket width. Numerical calculations are performed to verify all results. 9 refs., 6 figs.

  15. X-ray beam compression by tapered waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.-Y., E-mail: hchen2@gwdg.de, E-mail: tsaldit@gwdg.de; Hoffmann, S.; Salditt, T., E-mail: hchen2@gwdg.de, E-mail: tsaldit@gwdg.de [Institut für Röntgenphysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2015-05-11

    We have fabricated linear tapered waveguide channels filled with air and imbedded in silicon for the hard x-ray regime, using a processing scheme involving e-beam lithography, reactive ion etching, and wafer bonding. Beam compression in such channels is demonstrated by coupling a pre-focused undulator beam into the channels, and recording the exit flux and far-field diffraction patterns. We achieved a compressed beam with a spot size of 16.48 nm (horizontal) × 14.6 nm (vertical) near the waveguide exit plane, as determined from the reconstructed near-field distribution, at an exit flux which is eight times higher than that of an equivalent straight channel. Simulations indicate that this gain could reach three to four orders of magnitude for longer channels with tapering in two directions.

  16. A tapered poloidal gap for the reduction of field errors

    International Nuclear Information System (INIS)

    The conventional Reversed Field Pinch is surrounded by a toroidal conducting shell that provides wall stabilization for the plasma. Usually, this shell is made of aluminum or copper, and it must have an insulated poloidal gap to permit penetrations of toroidal loop voltage to the plasma. Many magnetic field perturbations will induce toroidal shell currents with poloidal Fourier components having mode numbers m ≥1. A butt-joint poloidal gap will mode convert all of these image currents into potentially damaging magnetic-field errors with large spectra of toroidal-mode numbers. Overlapping tapered gaps have been proposed and partially tested for reducing these field errors. The mathematical basis for minimizing the m = 1, n = 0 field errors for all frequencies using tapered gaps, is presented in this paper

  17. Reduced Amplitude Noise in Supercontinuum Generated in Tapered PCFs

    DEFF Research Database (Denmark)

    Møller, Uffe; Sørensen, Simon Toft; Moselund, P. M.;

    2011-01-01

    Supercontinuum generation (SCG) in highly nonlinear photonic crystal fibers (PCF) has drawn a lot of attention for the last decade. Pumping such PCFs with high-power picosecond laser pulses enables the creation of broadband and intense light [1]. Picosecond SCG is initiated by modulation instabil......Supercontinuum generation (SCG) in highly nonlinear photonic crystal fibers (PCF) has drawn a lot of attention for the last decade. Pumping such PCFs with high-power picosecond laser pulses enables the creation of broadband and intense light [1]. Picosecond SCG is initiated by modulation...... instability and as such contains some noise. It is thus of significant interest to reduce the noise. Here we therefore focus on the noise properties of such supercontinuum (SC) generated in tapered PCFs, and that the tapering reduces the noise at the spectral edge....

  18. Gas insulated transmission line having tapered particle trapping ring

    Science.gov (United States)

    Cookson, Alan H.

    1982-01-01

    A gas-insulated transmission line includes an outer sheath, an inner conductor, insulating supports and an insulating gas. A particle-trapping ring is secured to each insulating support, and it is comprised of a central portion and two tapered end portions. The ends of the particle trapping ring have a smaller diameter than the central portion of the ring, so as to enable the use of the particle trapping ring in a curved transmission line.

  19. Plasmonic Sensors Based on Doubly-Deposited Tapered Optical Fibers

    Science.gov (United States)

    González-Cano, Agustín; Navarrete, María-Cruz; Esteban, Óscar; Díaz-Herrera, Natalia

    2014-01-01

    A review of the surface plasmon resonance (SPR) transducers based on tapered fibers that have been developed in the last years is presented. The devices have proved their good performance (specifically, in terms of sensitivity) and their versatility and they are a very good option to be considered as basis for any kind of chemical and biological sensor. The technology has now reached its maturity and here we summarize some of the characteristics of the devices produced. PMID:24618726

  20. Plasmonic Sensors Based on Doubly-Deposited Tapered Optical Fibers

    Directory of Open Access Journals (Sweden)

    Agustín González-Cano

    2014-03-01

    Full Text Available A review of the surface plasmon resonance (SPR transducers based on tapered fibers that have been developed in the last years is presented. The devices have proved their good performance (specifically, in terms of sensitivity and their versatility and they are a very good option to be considered as basis for any kind of chemical and biological sensor. The technology has now reached its maturity and here we summarize some of the characteristics of the devices produced.

  1. Tapered Diode-pumped continuous-wave alexandrite laser

    OpenAIRE

    Beyatlı, Ersen; Sennaroğlu, Alphan; Baali, Ilyes; Sumpf, Bernd; Erbert, Goetz; Leitenstorfer, Alfred; Demirbaş, Ümit

    2013-01-01

    Tapered diode-pumped continuous-wave alexandrite laser Ersen Beyatli,1 Ilyes Baali,2 Bernd Sumpf,3 Götz Erbert,3 Alfred Leitenstorfer,4 Alphan Sennaroglu,1 and Umit Demirbas2,4,* 1Laser Research Laboratory, Departments of Physics and Electrical-Electronics Engineering, Koç University, Rumelifeneri, Sariyer, Istanbul 34450, Turkey 2Laser Technology Laboratory, Department of Electrical and Electronics Engineering, Antalya International University, 07190 Dosemealti, Antalya,...

  2. Comparative evaluation of apically extruded debris with V-Taper, ProTaper Next, and the Self-adjusting File systems

    Directory of Open Access Journals (Sweden)

    Nishant K Vyavahare

    2016-01-01

    Full Text Available Background: Complete cleaning of the root canal is the goal for ensuring success in endodontics. Removal of debris plays an important role in achieving this goal. In spite of advancements in instrument design, apical extrusion of debris remains a source of inflammation in the periradicular region. Aim: To comparatively evaluate the amount of apically extruded debris with V-Taper, ProTaper Next, and the self-adjusting File (SAF system. Materials and Methods: Sixty-four extracted human mandibular teeth with straight root canals were taken. Access openings were done and working length determined. The samples were randomly divided into three groups: Group I - V-Taper files (n = 20, Group II - ProTaper Next (n = 20, Group III - SAF (n = 20. Biomechanical preparation was completed and the debris collected in vials to be quantitatively determined. The data obtained was statistically analyzed using ANOVA and post hoc Tukey′s test. Results: All the specimens showed apical debris extrusion. SAF showed significantly less debris extrusion compared to V-Taper and ProTaper Next (P < 0.001. Among Groups I and II, ProTaper Next showed lesser debris extrusion as compared to V-Taper, but it was not significant (P = 0.124. Conclusion: The SAF showed least amount of apical debris extrusion when compared to newer rotary endodontic instruments. This indicates that the incidence of inter-treatment flare-ups due to debris extrusion would be less with the SAF.

  3. EFFECT OF TWO TAPERING METHODS ON INTERLEUKIN-6, CORTISOL AND PERFORMANCE IN ELITE MALE WRESTLER

    Directory of Open Access Journals (Sweden)

    Mehranpour A.B.

    2015-08-01

    Full Text Available Purpose : This study examined that effect of two types of tapering on interleukin-6(IL-6, cortisol and performance in elite male wrestler. Material : After 4 weeks of progressive training, wrestlers were randomly divided into three equal groups, 1-control group (N=10 continued performing progressive training for one week, 2-taper group 1 (N=10 continued with a 50% reduction in training volume for one week, 3-taper group 2 (N=10 continued with a 75% reduction in volume of training for one week .plasma blood IL-6 and cortisol levels were assayed from analysis obtained via standard ELISA. Also general strength of muscles was recorded as a performance test. All data were collected before and after progressive training and also after one week of tapering period. Results : There were significant reduction of IL-6 and cortisol levels in both tapering group comparing with control group (P≤0.05.There was significant reduction of IL-6 and cortisol levels among tapering 50% and tapering 75% after tapering period (P≤0.05. Also there was significant increase of general strength of muscles between tapering 75% and control group (P≤0.05. Conclusion : hence, one week tapering with 75% reduction in training volume after progressive training while the intensity kept high is effective strategy for reduction of IL-6, and cortisol levels and also increase performance. It seems that higher reduction of training volume when the intensity kept high is a good strategy for wrestler before main competition.

  4. Electromechanical analysis of tapered piezoelectric bimorph at high electric field

    Science.gov (United States)

    Chattaraj, Nilanjan; Ganguli, Ranjan

    2015-04-01

    Piezoelectric bimorph laminar actuator of tapered width exhibits better performance for out-of-plane deflection compared to the rectangular surface area, while consuming equal surface area. This paper contains electromechanical analysis and modeling of a tapered width piezoelectric bimorph laminar actuator at high electric field in static state. The analysis is based on the second order constitutive equations of piezoelectric material, assuming small strain and large electric field to capture its behavior at high electric field. Analytical expressions are developed for block force, output strain energy, output energy density, input electrical energy, capacitance and energy efficiency at high electric field. The analytical expressions show that for fixed length, thickness, and surface area of the actuator, how the block force and output strain energy gets improved in a tapered surface actuator compared to a rectangular surface. Constant thickness, constant length and constant surface area of the actuator ensure constant mass, and constant electrical capacitance. We consider high electric field in both series and parallel electrical connection for the analysis. Part of the analytical results is validated with the experimental results, which are reported in earlier literature.

  5. Magnetic field tunability of optical microfiber taper integrated with ferrofluid.

    Science.gov (United States)

    Miao, Yinping; Wu, Jixuan; Lin, Wei; Zhang, Kailiang; Yuan, Yujie; Song, Binbin; Zhang, Hao; Liu, Bo; Yao, Jianquan

    2013-12-01

    Optical microfiber taper has unique propagation properties, which provides versatile waveguide structure to design the tunable photonic devices. In this paper, the S-tapered microfiber is fabricated by using simple fusion spicing. The spectral characteristics of microfiber taper integrated with ferrofluid under different magnetic-field intensities have been theoretically analyzed and experimentally demonstrated. The spectrum are both found to become highly magnetic-field-dependent. The results indicate the transmission and wavelength of the dips are adjustable by changing magnetic field intensity. The response of this device to the magnetic field intensity exhibits a Langvin function. Moreover, there is a linear relationship between the transmission loss and magnetic field intensity for a magnetic field intensity range of 25 to 200Oe, and the sensitivities as high as 0.13056dB/Oe and 0.056nm/Oe have been achieved, respectively. This suggests a potential application of this device as a tunable all-in-fiber photonic device, such as magneto-optic modulator, filter, and sensing element. PMID:24514542

  6. How Tapered Roller Geometry Determines Bearing Energy Efficiency

    Directory of Open Access Journals (Sweden)

    Craig Seidelson

    2011-01-01

    Full Text Available With annual global sales of approximately $5 billion [1], tapered roller bearing consumers increasingly valued energy efficient products [2]. Two of the world’s largest bearing producers, SKF [3] and Timken [4] promoted energy efficient bearings based on their abilities to grind rollers to reduced radial deviation from round (OOR. Bearing designers, however, did not know if roller geometries specified placed limitations on roller roundness. Testing under shop floor conditions at Timken, the researcher discovered a positive linear regression between roller nominal diameter and OOR. The basis for the regression was under geometric roller rounding conditions found to exist when through feed centreless grinding tapered rollers, synchronous regulating wheel vibrations transferred at higher amplitude to larger nominal diameter rollers. This research pointed energy efficient bearing design in a new direction. For example, tapered roller bearing designers typically specified rollers of minimum length to reduce problems associated with rolling contact. Bearings assembled from shorter rollers, to retain the same load capacity, required fewer rollers of larger nominal diameter. This research, however, found all things equal larger nominal diameter rollers suffered from increased OOR. Bearings designed to reduce power losses associated with rotational displacements benefited from employing more, smaller nominal diameter rollers.

  7. Bamboo Taper Effect on Third Point Loading Bending Test

    Directory of Open Access Journals (Sweden)

    Naresworo Nugroho

    2013-06-01

    Full Text Available Geometrical shape of bamboo usually assumed as tapered hollow pipe. This study proved that the dimensional changes along the bamboo stem significantly affected to its Modulus of Rupture (SR value which measured from third point loading bending test. Therefore if the bending test applied using third point loading configuration, the SR value should be adjusted by strength ratio of taper (Ct. Ct is theratio between (SR calculated in the center span and the maximum bending stress along the bamboo beam. This study resulted mathematical formulae to calculate the Ct value for overall range of bamboo taper based on six species namely Tali (Gigantochloa apus (Bl.Ex Schult.f Kurz, Hitam (Gigantochloa atroviolaceae Widjaja, Andong (Gigantochloa psedorundinaceae, Ampel (Bambusa vulgaris Schrad, Gombong (Gigantochloa verticillata (Willd Munro, and Mayan (Gigantochloa robusta Kurz. The first tree species were obtained from the Bogor market, while the others were harvested from bamboo clumps in Arboretum Bamboo – Bogor Agricultural University. Then the formula was applied to sketch the graphical style in order to simplify the result.

  8. A prospective evaluation of outcomes of two tapered implant systems.

    Science.gov (United States)

    Andreasi Bassi, M; Lopez, M A; Confalone, L; Gaudio, R M; Lombardo, L; Lauritano, D

    2016-01-01

    The purpose of this prospective clinical study was to evaluate survival rate (SVR - i.e. fixtures still in place at the end of the observation period) and success rate (SCR - i.e. bone resorption around the implant neck) of two tapered implant systems. Both systems were equipped with a tapered connection, one requiring bone-level (BL) placement, while the other required soft-tissue-level (STL) placement. In the period between January 1996 and October 2011, 133 fixtures were inserted, 90 in females and 43 in males, with a mean age of 60±11 years. The mean post-surgical follow-up was 64±38 months. Several clinical parameters were evaluated as potential outcome conditioners. An SPSS program was used for statistical analysis and a Cox analysis was performed. The SVR was 100% since no fixtures were lost. SCR, expressed through the mean marginal bone loss, was 88%. No significant differences were found, for most of the variables investigated with the exception of bone grafting and implant type: STL implants showed a better clinical outcome than BL implants when bone grafting was performed simultaneously with implant placement. Tapered implants are reliable devices for oral rehabilitation of jaws. PMID:27469541

  9. Thermomechanical Behavior in Continuous Bloom Casting with Different Mold Tapers

    Institute of Scientific and Technical Information of China (English)

    LUO Xin; CHEN Yong; SHEN Houfa

    2008-01-01

    A two-dimensional finite element model was used to analyze the thermal and mechanical behavior dunng solidification of the strand in a continuous bloom casting mold.The coupled heat transfer and defermation were analyzed to simulate the formation of the air gap between the mold and the strand.The model was used to investigate the influence of mold taper on the temperature and stress distributions in the strand.The results show that the air gap mainly forms around the strand corner,causing a hoRer and thinner solidifying shell in this region.The mold taper partially compensates for the strand shell shnnkage and reduces the infiuence of the air gap on the heat transfer.The mold taper compresses the shell and changes the stress state around the stmnd comer region.As the strand moves down into the mold,the mold constraint causes compressive stress beneath the comer surface.which reduces the hot tear that forms on the strand.

  10. Microbiological Seal of Two Types of Tapered Implant Connections.

    Science.gov (United States)

    Peruzetto, Wheslley M; Martinez, Elizabeth F; Peruzzo, Daiane C; Joly, Júlio Cesar; Napimoga, Marcelo H

    2016-01-01

    Tapered implant connections have gained wide popularity for being more resistant to fatigue and for promoting a better seal against bacterial infiltration than conventional connections. The aim of this study was to evaluate the bacterial seal at the implant-abutment interface using two Morse taper implant models, by in vitro microbiological analysis. Eleven non-indexed and 11 indexed abutments were selected and connected to their respective implants with a 20 N torque, according to manufacturer's recommendation. Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. For control, one non-contaminated abutment-implant set from each group (negative control) and one contaminated implant with no abutment (positive control) were used. The specimens were immersed in BHI broth and maintained in an incubator at 37 °C for 14 days to assess the development of bacterial contamination. The results revealed that 36.4% (n=4) of the indexed components and 90.9% (n=10) of the non-indexed components allowed bacterial leakage, with significant difference between groups (p=0.0237). In conclusion, both tapered components failed to provide adequate sealing to bacterial leakage, although the indexed type components showed a superior seal compared with non-indexed components. PMID:27224559

  11. Manipulating rogue wave triplet in optical waveguides through tapering

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Rama [Department of Physics, DAV University, Jalandhar 144008 (India); Kumar, C.N., E-mail: cnkumar@pu.ac.in [Department of Physics, Panjab University, Chandigarh 160014 (India); Vyas, Vivek M. [Institute of Mathematical Sciences, CIT Campus, Taramani, Chennai 600 113 (India); Panigrahi, Prasanta K., E-mail: pprasanta@iiserkol.ac.in [Indian Institute of Science Education and Research – Kolkata, Mohanpur, Nadia 741252 (India)

    2015-02-06

    Taking account of the results of the paper, published in [21] (Chabchoub and Akhmediev, 2013), containing experimental generation of rogue wave triplets in the water tank, we demonstrate a theoretical approach to coherently control the rogue wave triplet dynamics and spectral spread in a tapered index optical waveguide. The relative distance between the successive waves of the triplet, along both longitudinal and transverse axes, can be manipulated by modulating the tapering of the waveguide. This not only significantly enhances the possibility of observing these statistically rare events in the waveguide, but can also controllably amplify the intensity and spectral spread, the desired features for supercontinuum generation. The controlling of real Riccati parameter intrinsically arises from the allowed phase variation of the self-similar solutions of the nonlinear Schrödinger equation. - Highlights: • Manipulating rogue wave triplets in GNLSE using Riccati parameter is outlined. • Symmetric transformations used to scale mutual spacing in a triplet. • Results presented for sech{sup 2}-type tapered waveguides.

  12. Should Psychiatrists Resurrect the Body?

    Science.gov (United States)

    Benning, Tony B

    2016-01-01

    The current article interrogates the mind-body dualism that characterizes modern psychiatry and contends that the dualism is manifested by the relative neglect by psychiatrists of the body, or soma. The article argues that the state of affairs has several consequences, including psychiatrists' underappreciation of the somatic manifestations of mental disorders and of the therapeutic potential of somatic or body-based therapies. Empirical data attest to the association of a range of mental illnesses with somatic pathologies, as does the fact that a range of somatic therapies, including yoga and t'ai chi, are increasingly being shown to be efficacious in the treatment of a range of mental illnesses. The current article contextualizes contemporary Western psychiatry's relative neglect of the body by drawing on some historical as well as cross-cultural perspectives. Although their overall effect has been minimal, various theoretical perspectives in Western psychiatry, including Jungian thought, psychoanalytical psychosomatics, Reichian and related schools, and the phenomenological tradition, have sought to overcome psychiatry's mind-body dualism. Neither has psychiatry incorporated the values of various non-Western schools of medicine that maintain a far more integrated conceptualization of the relationship between mind and body than is seen in modern Western psychiatry. The field of psychosomatics could potentially influence general psychiatry to reverse its bifurcated mind-body relationship, but that field's increasingly narrow mandate and organizational separation from general psychiatry conspire to militate against the latter's incorporation of psychosomatic medicine's conceptual advances or pragmatic insights in any convincing or enduring manner. PMID:26878681

  13. A Tapered Aluminium Microelectrode Array for Improvement of Dielectrophoresis-Based Particle Manipulation

    OpenAIRE

    Muhamad Ramdzan Buyong; Farhad Larki; Mohd Syafiq Faiz; Azrul Azlan Hamzah; Jumrail Yunas; Burhanuddin Yeop Majlis

    2015-01-01

    In this work, the dielectrophoretic force (FDEP) response of Aluminium Microelectrode Arrays with tapered profile is investigated through experimental measurements and numerical simulations. A standard CMOS processing technique with a step for the formation of a tapered profile resist is implemented in the fabrication of Tapered Aluminium Microelectrode Arrays (TAMA). The FDEP is investigated through analysis of the Clausius-Mossotti factor (CMF) and cross-over frequency (fxo). The performan...

  14. Influence of internally dropped-off plies on the impact damage of asymmetrically tapered laminated CFRP

    OpenAIRE

    Abdulhamid, Hakim; Bouvet, Christophe; Michel, Laurent; Aboissière, Jacky; Minot, Clément

    2015-01-01

    This paper presents an experimental study of low velocity impact response of carbon/epoxy asymmetrically tapered laminates. The tests are realised at energy between 10 and 30 J on two types of layup with multiple terminated plies. The type and localisation of damage are analysed using C-scan and micrographs. Then, the data is compared with the response of corresponding respective plain laminate. The effects of some tapering parameters (taper angle, drop-off disposition and configuration) o...

  15. Wear patterns of taper connections in retrieved large diameter metal-on-metal bearings.

    Science.gov (United States)

    Bishop, Nicholas; Witt, Florian; Pourzal, Robin; Fischer, Alfons; Rütschi, Marcel; Michel, Markus; Morlock, Michael

    2013-07-01

    Wear of the modular taper between head and shaft has been related to clinical failure resulting from adverse reactions to metallic debris. The problem has become pronounced in large metal-on-metal bearings, but the mechanism has not yet been fully understood. We analyzed retrieved components from five patients revised with various diagnoses. Two distinct wear patterns were observed for the head tapers. Three samples demonstrated "asymmetric" wear towards the inner end of the head taper. The other two showed "axisymmetric" radial wear (up to 65 µm) presenting the largest wear volumes (up to 20 mm(3)). Stem tapers demonstrated relatively little wear, and the fine thread on the stem taper surface was observed to be imprinted on the taper inside of the head. Our findings demonstrate that the cobalt-chrome head wears preferentially to the titanium stem taper. "asymmetric" wear suggests toggling due to the offset of the joint force vector from the taper. In contrast, samples with "axisymmetric" radial wear and a threaded imprint suggested that corrosion led to head subsidence onto the stem taper with gradual rotation. PMID:23440943

  16. Single quantum dot spectroscopy using a fiber taper waveguide near-field optic

    OpenAIRE

    Srinivasan, Kartik; Stintz, Andreas; Krishna, Sanjay; Painter, Oskar

    2007-01-01

    Photoluminescence spectroscopy of single InAs quantum dots at cryogenic temperatures (~14 K) is performed using a micron-scale optical fiber taper waveguide as a near-field optic. A lower bound on the measured collection efficiency of quantum dot spontaneous emission into the fundamental guided mode of the fiber taper is estimated at 0.1%, and spatially resolved measurements with ~600 nm resolution are obtained by varying the taper position with respect to the sample and using the fiber taper...

  17. Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan; Yvind, Kresten; Hvam, Jørn Märcher

    2010-01-01

    width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler for......An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering the...

  18. Nonlinear effects generation in non-adiabatically tapered fibres

    Science.gov (United States)

    Palací, Jesús; Mas, Sara; Monzón-Hernández, David; Martí, Javier

    2015-12-01

    Nonlinear effects are observed in a non-adiabatically tapered optical fibre. The designed structure allows for the introduction of self-phase modulation, which is observed through pulse breaking and spectral broadening, in approximately a centimetre of propagation using a commercial telecom laser. These devices are simple to fabricate and suitable to generate and control a variety of nonlinear effects in practical applications because they do not experience short-term degradation as previously reported approaches. Experimental and theoretical results are obtained, showing a good agreement.

  19. Nanocoating effects on tapered long period fiber gratings

    Science.gov (United States)

    Pilla, P.; Cusano, A.; Cutolo, A.; Giordano, M.; Korwin-Pawlowski, M. L.; Bock, W. J.

    2007-07-01

    In this work, the experimental analysis of the response of nanocoated Tapered Long Period Gratings (TLPGs) to Surrounding Refractive Index (SRI) changes is presented. The modal transition is demonstrated to take place in this kind of devices and to be an effective method to improve their SRI sensitivity. The dip-coating method was carried out by an automated system and showed to be a reliable technique for the deposition of conformal coatings. A comparison with traditional UV-written LPGs revealed that a thicker overlay is necessary for the TLPG to tune the transition region in the same SRI range.

  20. Modeling taper charge with a non-linear equation

    Science.gov (United States)

    Mcdermott, P. P.

    1985-01-01

    Work aimed at modeling the charge voltage and current characteristics of nickel-cadmium cells subject to taper charge is presented. Work reported at previous NASA Battery Workshops has shown that the voltage of cells subject to constant current charge and discharge can be modeled very accurately with the equation: voltage = A + (B/(C-X)) + De to the -Ex where A, B, D, and E are fit parameters and x is amp-hr of charge removed during discharge or returned during charge. In a constant current regime, x is also equivalent to time on charge or discharge.

  1. Laser field distribution near inclined taper optical antenna

    International Nuclear Information System (INIS)

    This work focuses on the mechanism of laser field enhancement within a gap between a taper plasmonic nanoantenna and a dielectric substrate in the inverted optical configuration. We show that field enhancement factor depends on several parameters such as: tip-sample distance, radius of curvature of the tip and its inclination angle in respect to the substrate. In particular, a relation between the field enhancement near the tip apex and the inclination angle is deduced. Numerical simulation and optimization were performed within the framework of the FDTD method and the Green function formalism

  2. Lanthanum hexaboride tapered filament in a plasma source

    International Nuclear Information System (INIS)

    A directly heated lanthanum hexaboride tapered filament has been tested in a plasma generator. A uniform temperature distribution at 1820 K has been achieved. The heating and cooling power calculated from measured quantities are balanced. A maximum arc current of 80 A was obtained, limited only by the power supply and plasma generator. The corresponding hydrogen ion current density was 0.6 A/cm2 when the arc voltage was 80 V and the filament heater current was about 5 A. The filament was capable of emitting 100 A of current at an operating temperature of 1900 K. The estimated lifetime for this filament is 900 h

  3. Supercontinuum Generation in Uniform and Tapered Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Møller, Uffe Visbech; Larsen, Casper;

    Supercontinuum generation (SCG) is a striking phenomenon of extreme spectral broadening involving a wealth of beautiful nonlinear physics. The study of SCG and development of today’s commercial sources really took off with the invention of the photonic crystal fiber (PCF), in which light can be...... describe the underlying mechanisms responsible for SCG in PCFs, and show how the position and power in the spectral edges can be manipulated by tapering the fiber to achieve, e.g., spectra extending into the ultraviolet. This is motivated by the huge commercial potential of blue-extended supercontinuum...

  4. Supercontinuum generation in dispersion-managed tapered-rib waveguide.

    Science.gov (United States)

    Hu, Hongyu; Li, Wenbo; Dutta, Niloy K

    2013-10-20

    We have designed a tapered-rib waveguide and numerically studied the generation of supercontinuum using such waveguides. The Air-SF57 glass-SiO(2) waveguide is 3 cm long, with a varying etched depth to manage the total dispersion. Numerical simulations are conducted for input pulses at a wavelength of 1.55 μm with a width of 150 fs and peak power of 5 kW. The proposed waveguide geometry greatly broadens the output spectrum, extending from ∼1 to ∼6  μm, caused by the continuous modification of the phase-matching condition for the generated waves. PMID:24216588

  5. Dispersion-engineered tapered planar waveguide for coherent supercontinuum generation

    Science.gov (United States)

    Hu, Hongyu; Li, Wenbo; Dutta, Niloy K.

    We have designed a tapered planar rib waveguide and numerically studied supercontinuum generation by the propagation of input pulses at 1.55 μm. The Air-SF57 glass-SiO2 waveguide is 2 cm long, with a varying etch depth to manage the total dispersion. This proposed waveguide geometry significantly broadens the output spectrum caused by continuous modification of the phase matching condition for dispersive wave emission. The coherence property has also been investigated, demonstrating that fully coherent supercontinuum extending from ~1 μm to ~4.6 μm can be obtained with proper pumping conditions.

  6. Analysis of guided wave propagation in a tapered composite panel

    Science.gov (United States)

    Wandowski, Tomasz; Malinowski, Pawel; Moll, Jochen; Radzienski, Maciej; Ostachowicz, Wieslaw

    2015-03-01

    Many studies have been published in recent years on Lamb wave propagation in isotropic and (multi-layered) anisotropic structures. In this paper, adiabatic wave propagation phenomenon in a tapered composite panel made out of glass fiber reinforced polymers (GFRP) will be considered. Such structural elements are often used e.g. in wind turbine blades and aerospace structures. Here, the wave velocity of each wave mode does not only change with frequency and the direction of wave propagation. It further changes locally due to the varying cross-section of the GFRP panel. Elastic waves were excited using a piezoelectric transducer. Full wave-field measurements using scanning Laser Doppler vibrometry have been performed. This approach allows the detailed analysis of elastic wave propagation in composite specimen with linearly changing thickness. It will be demonstrated here experimentally, that the wave velocity changes significantly due to the tapered geometry of the structure. Hence, this work motivates the theoretical and experimental analysis of adiabatic mode propagation for the purpose of Non-Destructive Testing and Structural Health Monitoring.

  7. Temperature control of ion guiding through tapered capillaries

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, Elisabeth, E-mail: egruber@iap.tuwien.ac.at [Institute of Applied Physics, TU Wien – Vienna University of Technology, 1040 Vienna (Austria); Stolterfoht, Nikolaus [Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin (Germany); Allinger, Peter; Wampl, Stefan [Institute of Applied Physics, TU Wien – Vienna University of Technology, 1040 Vienna (Austria); Wang, Yuyu [Institute of Applied Physics, TU Wien – Vienna University of Technology, 1040 Vienna (Austria); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu (China); Simon, Marius J. [Labor für Ionenstrahlphysik, ETH Zürich, 8093 Zürich (Switzerland); Aumayr, Friedrich, E-mail: aumayr@iap.tuwien.ac.at [Institute of Applied Physics, TU Wien – Vienna University of Technology, 1040 Vienna (Austria)

    2014-12-01

    We investigate the guiding of Ar{sup 7+} ions (kinetic energy of 4.5 keV) through a single macroscopic tapered glass capillary of conical shape as a function of capillary tilt angle with respect to the incident ion beam direction. At room temperature a minimum in the transmitted ion intensity appears around the forward direction, which was previously observed and interpreted by a blocking of the transmission by repulsive Coulomb forces due to a uniformly charged ring shaped region in the centre part of the capillary. By heating the tapered capillary to temperatures around 100 °C and thus drastically increasing the electrical conductivity of the capillary material we no longer observe a minimum in the transmission curve but the transmission curve now has its maximum in forward direction. Since the maximum transmission at high temperature in forward direction is still smaller than the minimum in transmitted intensity at room temperature, we conclude that even at room temperature and in forward direction the focusing effect due to guiding is dominant and only partially weakened by blocking. Our experimental results are well reproduced in simulations using a theoretical model originally developed for straight nano-capillaries.

  8. Fatigue Life Analysis of Tapered Hybrid Composite Flexbeams

    Science.gov (United States)

    Murri, Gretchen B.; Schaff, Jeffery R.; Dobyns, Alan L.

    2002-01-01

    Nonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.

  9. Fatigue Life Methodology for Tapered Hybrid Composite Flexbeams

    Science.gov (United States)

    urri, Gretchen B.; Schaff, Jeffery R.

    2006-01-01

    Nonlinear-tapered flexbeam specimens from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. Two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) associated with simulated delamination growth in the flexbeams are presented from both codes. These results compare well with each other and suggest that the initial delamination growth from the tip of the ply-drop toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves for comparison with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared well with the test results.

  10. Optimization of epitaxial layer design for high brightness tapered lasers

    Science.gov (United States)

    Tijero, J. M. G.; Rodriguez, D.; Borruel, L.; Sujecki, S.; Larkins, E. C.; Esquivias, I.

    2005-04-01

    A comparative simulation study of the optical output characteristics of tapered lasers with different epitaxial structure was performed. The simulation model self-consistently solves the steady state electrical and optical equations for the flared unstable resonator and was previously backed by experiments on one of the simulated structures. Three different epitaxial designs emitting at 975 nm were analyzed: a standard single quantum well symmetrically located in the confinement region (s-SQW), a double quantum well also symmetrically located (s-DQW) and an asymmetrically located double quantum well (a-DQW). The symmetric structures have different confinement factor but a similar ratio between the active layer thickness and the confinement factor, dQW/Γ, while the a-DQW has similar confinement factor than the s-SQW, but double dQW/Γ. A better performance is predicted for the a-DQW design, reaching considerably higher output power with good beam quality. The results are interpreted in terms of a lower density of power in the QW in the case of the a-DQW design, thus delaying to higher output power the onset of the non-linear effects that degrade the beam quality. The role of dQW/Γ as a figure of merit for high brightness tapered lasers is emphasized.

  11. Dynamic analysis of tapered laminated composite magnetorheological elastomer (MRE) sandwich plates

    Science.gov (United States)

    Babu, V. Ramesh; Vasudevan, R.

    2016-03-01

    In the present study, the dynamic performance of the sandwich plate with magneto rheological elastomer (MRE) as the core layer and tapered laminated composite plates as the face layers is investigated. Various MRE tapered laminated composite sandwich plate models are formulated by dropping-off the plies longitudinally in top and bottom composite layers to yield tapered plates as the face layers and uniform MRE layer as the core layer. The governing equations of motion of tapered composite MRE sandwich plates are derived using classical laminated plate theory and solved numerically. Further, silicon based MRE is being fabricated and tested to obtain the shear and loss moduli using MR rheometer. The efficacy of the finite element formulation is validated by carrying out experiments on the various prototypes of tapered composite silicon based MRE sandwich plates and comparing the results in terms of natural frequencies obtained at various magnetic fields with those obtained numerically and with available literature. Also, the effects of magnetic field, taper angle of the top and bottom layers, aspect ratio, ply orientations and various end conditions on the various dynamic properties of tapered laminated composite MRE sandwich plate are investigated. Further, the transverse vibration responses of three different tapered composite MRE based sandwich plates under harmonic force excitation are analyzed at various magnetic fields.

  12. Tapering of Polymer Optical Fibers for Compound Parabolic Concentrator Fiber Tip Fabrication

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Fasano, Andrea; Nielsen, Kristian; Aasmul, Søren; Rasmussen, Henrik K.; Bang, Ole

    2015-01-01

    We propose a process for Polymer Optical Fiber (POF) Compound Parabolic Compound (CPC) tip manufacturing using a heat and pull fiber tapering technique. The POF, locally heated above its glass transition temperature, is parabolically tapered down in diameter, after which it is cut to the desired...

  13. Controlling the emission profile of a nanowire with a conical taper

    DEFF Research Database (Denmark)

    Gregersen, Niels; Nielsen, Torben Roland; Claudon, J.;

    2008-01-01

    The influence of a tapering on nanowire light-emission profiles is studied. We show that, for nanowires with divergent output beams, the introduction of a conical tapering with a small opening angle reduces the beam divergence and increases transmission. This results in a dramatic increase in the...

  14. Tapering Talk: The Impact of Expectations of Reduced Federal Reserve Security Purchases on Emerging Markets

    OpenAIRE

    Eichengreen, Barry; Gupta, Poonam

    2014-01-01

    In May 2013, Federal Reserve officials first began to talk of the possibility of tapering their security purchases. This tapering talk had a sharp negative impact on emerging markets. Different countries, however, were affected very differently. This paper uses data on exchange rates, foreign reserves and equity prices between April and August 2013 to analyze who was hit and why. It finds ...

  15. Comparative evaluation of apically extruded debris with V-Taper, ProTaper Next, and the Self-adjusting File systems

    Science.gov (United States)

    Vyavahare, Nishant K.; Raghavendra, Srinidhi Surya; Desai, Niranjan N.

    2016-01-01

    Background: Complete cleaning of the root canal is the goal for ensuring success in endodontics. Removal of debris plays an important role in achieving this goal. In spite of advancements in instrument design, apical extrusion of debris remains a source of inflammation in the periradicular region. Aim: To comparatively evaluate the amount of apically extruded debris with V-Taper, ProTaper Next, and the self-adjusting File (SAF) system. Materials and Methods: Sixty-four extracted human mandibular teeth with straight root canals were taken. Access openings were done and working length determined. The samples were randomly divided into three groups: Group I - V-Taper files (n = 20), Group II - ProTaper Next (n = 20), Group III - SAF (n = 20). Biomechanical preparation was completed and the debris collected in vials to be quantitatively determined. The data obtained was statistically analyzed using ANOVA and post hoc Tukey's test. Results: All the specimens showed apical debris extrusion. SAF showed significantly less debris extrusion compared to V-Taper and ProTaper Next (P endodontic instruments. This indicates that the incidence of inter-treatment flare-ups due to debris extrusion would be less with the SAF. PMID:27217636

  16. Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

    Directory of Open Access Journals (Sweden)

    Mary Kinue Nakamune Uezu

    2010-12-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars. MATERIAL AND METHODS: The amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris. RESULTS: ProTaper Universal files were significantly faster (p=0.0011 than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion. CONCLUSIONS: ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris.

  17. Two-octave spectral broadening of subnanojoule Cr:forsterite femtosecond laser pulses in tapered fibers

    Science.gov (United States)

    Akimov, D. A.; Ivanov, A. A.; Alfimov, M. V.; Bagayev, S. N.; Birks, T. A.; Wadsworth, W. J.; Russell, P. St. J.; Fedotov, A. B.; Pivtsov, V. S.; Podshivalov, A. A.; Zheltikov, A. M.

    Spectral broadening of femtosecond Cr:forsterite laser pulses is enhanced due to the use of tapered fibers. Supercontinuum generation with unamplified subnanojoule femtosecond Cr:forsterite laser pulses is observed for the first time. With 40-fs 0.6-nJ pulses of 1.25-μm Cr:forsterite laser radiation coupled into a tapered fiber having a taper waist diameter of about 2 μm and a taper waist length of 90 mm, we observed the spectra spanning more than two octaves at the output of the fiber in the regime of anomalous group-velocity dispersion. This result opens the way for the creation of compact femtosecond Cr:forsterite laser plus tapered fiber systems for optical metrology and biomedical applications.

  18. Acousto-optic interaction in biconical tapered fibers: shaping of the stopbands

    Science.gov (United States)

    Ramírez-Meléndez, Gustavo; Bello-Jiménez, Miguel Ángel; Cuadrado-Laborde, Christian; Díez, Antonio; Cruz, José Luis; Rodríguez-Cobos, Amparo; Balderas-Navarro, Raúl; Andrés Bou, Miguel Vicente

    2016-03-01

    The effect of a gradual reduction of the fiber diameter on the acousto-optic (AO) interaction is reported. The experimental and theoretical study of the intermodal coupling induced by a flexural acoustic wave in a biconical tapered fiber shows that it is possible to shape the transmission spectrum, for example, substantially broadening the bandwidth of the resonant couplings. The geometry of the taper transitions can be regarded as an extra degree of freedom to design the AO devices. Optical bandwidths above 45 nm are reported in a tapered fiber with a gradual reduction of the fiber down to 70 μm diameter. The effect of including long taper transition is also reported in a double-tapered structure. A flat attenuation response is reported with 3-dB stopband bandwidth of 34 nm.

  19. Comparison of the fracture resistance of dental implants with different abutment taper angles.

    Science.gov (United States)

    Wang, Kun; Geng, Jianping; Jones, David; Xu, Wei

    2016-06-01

    To investigate the effects of abutment taper angles on the fracture strength of dental implants with TIS (taper integrated screwed-in) connection. Thirty prototype cylindrical titanium alloy 5.0mm-diameter dental implants with different TIS-connection designs were divided into six groups and tested for their fracture strength, using a universal testing machine. These groups consisted of combinations of 3.5 and 4.0mm abutment diameter, each with taper angles of 6°, 8° or 10°. 3-Dimensional finite element analysis (FEA) was also used to analyze stress states at implant-abutment connection areas. In general, the mechanical tests found an increasing trend of implant fracture forces as the taper angle enlarged. When the abutment diameter was 3.5mm, the mean fracture forces for 8° and 10° taper groups were 1638.9N±20.3 and 1577.1N±103.2, respectively, both larger than that for the 6° taper group of 1475.0N±24.4, with the largest increasing rate of 11.1%. Furthermore, the difference between 8° and 6° taper groups was significant, based on Tamhane's multiple comparison test (Pimplants with different abutment taper angles and supported the findings of the static tests. In conclusion, increases of the abutment taper angle could significantly increase implant fracture resistance in most cases established in the study, which is due to the increased implant wall thickness in the connection part resulting from the taper angle enlargement. The increasing effects were notable when a thin implant wall was present to accommodate wide abutments. PMID:27040208

  20. A New Stem Taper Function for Short-rotation poplar

    Energy Technology Data Exchange (ETDEWEB)

    Benbrahim, Mohammed [INRA Centre de Bordeaux, Cestas (France). Unite de Recherches Forestieres; Gavaland, Andre [INRA Centre de Toulouse, Castanet-Tolosane (France). Unite Agroforesterie et Foret Paysanne

    2003-07-01

    A new stem taper function was established for individual trees of two poplar hybrid clones grown on a short-rotation coppice. The model could be easily fitted and required three parameters to be estimated. It can be used to estimate both diameter at a given height and height for a given top diameter. Two of the three parameters controlled the conical and the neiloid parts of the stem. Significant differences in these parameters were observed between the two clones even if no differences were observed for diameter at breast height or total height of the stem. The model could not be integrated to calculate volumes (total volume, merchantable volume), which were estimated by numerical integration. However, use of this new model allows the optimal length of billets to be determined and thus maximizes the merchantable biomass of poplar in short-rotation coppice by minimizing the biomass of residues.

  1. Efficiency enhancement of anomalous-Doppler electron cyclotron masers with tapered magnetic field

    International Nuclear Information System (INIS)

    The efficiency of slow-wave electron cyclotron masers (ECM) is usually low, thus limiting the practical applications. Here, a method of tapered magnetic field is introduced for the efficiency enhancement of the slow-wave ECM. The numerical calculations show that the tapered magnetic-field method can enhance the efficiency of slow-wave ECM significantly. The effect of beam electron velocity spread on the efficiency has also been studied. Although the velocity spread reduces the efficiency, a great enhancement of efficiency can still be obtained by the tapered magnetic field method

  2. Simulation on friction taper plug welding of AA6063-20Gr metal matrix composite

    Science.gov (United States)

    Hynes, N. Rajesh Jesudoss; Nithin, Abeyram M.

    2016-05-01

    Friction taper plug welding a variant of friction welding is useful in welding of similar and dissimilar materials. It could be used for joining of composites to metals in sophisticated aerospace applications. In the present work numerical simulation of friction taper plug welding process is carried out using finite element based software. Graphite reinforced AA6063 is modelled using the software ANSYS 15.0 and temperature distribution is predicted. Effect of friction time on temperature distribution is numerically investigated. When the friction time is increased to 30 seconds, the tapered part of plug gets detached and fills the hole in the AA6063 plate perfectly.

  3. Hollow-core tapered coupler for large inner diameter hollow-core optical fibers

    Institute of Scientific and Technical Information of China (English)

    Guiyao Zhou(周桂耀); Zhiyun Hou(侯峙云); Lantian Hou(侯蓝田); Jigang Liu(刘继刚)

    2003-01-01

    A novel hollow-core tapered coupler has been theoretically designed and fabricated by fiber drawing machine. The coupler's inner wall is coated with a polycrystalline GeO2 film. The coupling loss of hollow-core tapered coupler is about 0.2 dB. Hollow-core tapered coupler reduces the transmission loss of hollow-core optical fiber (HCOF) by 0.5 dB/m, therefore the coupler is suitable for coupling high power CO2 laser in industrial application.

  4. Enhanced terahertz transmission through a periodic array of tapered rectangular apertures

    CERN Document Server

    Devi, Koijam Monika; Kumar, Gagan

    2016-01-01

    We numerically analyse extraordinary terahertz transmission properties of an array of rectangular shaped apertures perforated periodically on a thin metal film. The apertures are tapered at different angles to achieve higher field concentration at the tapered end. The periodic sub-wavelength scale apertures ensure plasmonic behaviour giving rise to the enhanced transmission of a specific frequency mode decided by the periodicity. We compare results of transmission with the rectangular shaped apertures of same parameters and observe a significant increase in the transmission for the tapered case. We have compared results of our numerical simulations with theory and have found them consistent.

  5. Analytical Solution of a Tapering Cable Equation for Dendrites and Conformal Symmetry

    Science.gov (United States)

    Romero, Juan M.; Trenado, Carlos

    2015-09-01

    Progress towards detailed characterization of structural and biophysical properties of dendrites emphasizes the importance of finding analytical solutions for more realistic dendrite models with circular cross-section and varying diameter. In this regard, we employ symmetry methods and the passive cable theory to deduce a generalized analytical solution for electric propagation in a family of tapering dendrites. In particular, we study the effect of such tapering geometries on the obtained electric voltage. Simulations using the deduced analytical solution indicate that for a subfamily of tapering profiles neural integration is better than in the stereotypical profile given by a cylinder.

  6. Treatment with stereotactic radiotherapy body in lung cancer using tomography with taper beam of megavoltage

    International Nuclear Information System (INIS)

    Analyzes variations inter and intra fraction and their corrections online, for this case and for the 13 first. We study the dosimetric parameters recommended in the RTOG 0813 Protocol. Reported global dosimetry of treatments; discussed pros and cons of this methodology. (Author)

  7. Novel Route to Fabrication of Metal-Sandwiched Nanoscale Tapered Structures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yang; YU Da-Peng

    2009-01-01

    Tapered dielectric structures in metal have exhibited extraordinary performance in both surface plasmon polariton (SPP) waveguiding and SPP focusing.This is crucial to plazmonic research and industrial plasmonic device integration.We present a method that facilitates easy fabrication of smooth-surfaced sub-micron tapered structures in large scale simply with electron beam lithography (EBL).When a PMMA layer is spin-coated on previously-EBL-defined PMMA structures,steep edges can be transformed into a declining slope to form tapered PMMA structures,scaled from 10nm to 1000nm.Despite the simplicity of our method,patterns with PMMA surface smoothness can be well-positioned and replicated in large numbers,which therefore gives scientists easy access to research on the properties of tapered structures.

  8. Tapered optical fibers as tools for probing magneto-optical trap characteristics

    International Nuclear Information System (INIS)

    We present a novel technique for measuring the characteristics of a magneto-optical trap (MOT) for cold atoms by monitoring the spontaneous emission from trapped atoms coupled into the guided mode of a tapered optical nanofiber. We show that the nanofiber is highly sensitive to very small numbers of atoms close to its surface. The size and shape of the MOT, determined by translating the cold atom cloud across the tapered fiber, is in excellent agreement with measurements obtained using the conventional method of fluorescence imaging using a charge coupled device camera. The coupling of atomic fluorescence into the tapered fiber also allows us to monitor the loading and lifetime of the trap. The results are compared to those achieved by focusing the MOT fluorescence onto a photodiode and it was seen that the tapered fiber gives slightly longer loading and lifetime measurements due to the sensitivity of the fiber, even when very few atoms are present.

  9. Vector rectangular-shape laser based on reduced graphene oxide interacting with long fiber taper

    CERN Document Server

    Gao, Lei; Zeng, Jing; Huang, Wei; Liu, Min

    2014-01-01

    A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber taper deposited with reduced graphene oxide is proposed, where the nonlinearity is enhanced due to large evanescent-field-interacting length and strong field confinement of a 8 mm fiber taper with a waist diameter of 4 micronmeters. Graphene flakes are deposited uniformly on the taper waist with light pressure effect, so this structure guarantees both excellent saturable absorption and high nonlinearity. The RSL with a repetition rate of 7.9 MHz exhibits fast polarization switching in two orthogonal polarization directions, and the temporal and spectral characteristics are investigated. The results suggest that the long taper-based graphene structure is an efficient choice for nonlinear devices.

  10. Asymmetric first order shear horizontal guided waves propagation in a tapered plate

    International Nuclear Information System (INIS)

    In this paper, through numerical simulation of the first order shear horizontal guided waves propagation in a homogeneous tapered plate, we have realized sound unidirectional transmission based on the mode conversion mechanism. We also find that the contrast transmission ratio of unidirectional transmission is highly influenced by the slope angle of tapered edge. And the working frequency range of the asymmetric transmission can be easily controlled by the height of tapered surface or the thickness of slab. This asymmetric system shows potentially significant applications in various sound devices. - Highlights: • We study the sound unidirectional transmission for SH1 guided wave in a homogeneous tapered plate. • The contrast transmission ratio of unidirectional transmission is highly influenced by the slope angle. • The working frequency range of unidirectional transmission can be easily controlled by structure parameters

  11. Study of mode propagation with 632.8-nm laser in tapered fiber

    Institute of Scientific and Technical Information of China (English)

    He Chen; Junliang Lu; Chengliang Zhao; Botao Cheng; Xuanhui Lu

    2009-01-01

    The material dispersion of a tapered fiber is described by Sellmeier's equation.The dependence of refractive index on wavelength and doping concentration is discussed.A He-Ne laser with the output wavelength of 632.8 nm is used in the experiment.When the cutoff frequency of the fiber is less than the laser frequency,the guiding modes of a single-mode fiber(at 1550 nm)are investigated.The results show that the original single-mode fiber becomes a multi-mode waveguide.The propagation and mode coupling of the light in the taper region are analyzed.By controlling the taper end size of the fiber,the unique tapered fiber can convert a multi-mode beam into a single-mode one.

  12. Label free detection of DNA hybridization by refractive index tapered fiber biosensor

    Science.gov (United States)

    Zibaii, M. I.; Latifi, H.; Ghanati, E.; Gholami, M.; Hosseini, S. M.

    2010-04-01

    We demonstrate a simple refractive index sensor (RI) sensing system based on a biconical tapered optical fiber (BTOF), which is fabricated by heat pulling method, utilizing a CO2 laser. In this work we explore the application of these sensors for the detection of label free single stranded DNA (ssDNA) in real time. During the experiment, the target ssDNA did not need to be labeled with a fluorescent tag, which is expensive and complicated. The change in output optical transmission of the tapered fiber was recorded for Poly-L-Lysine (PLL) coating, ssDNA probe immobilization and hybridization. The result indicated that due to the hybridization with the complementary target ssDNA on the tapered surface, the RI of surrounding medium changes which leads to changes in the characteristics of the tapered region and change in the output power of the sensor.

  13. Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil

    Science.gov (United States)

    Nunes, Matheus Henrique

    2016-01-01

    Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects. PMID:27187074

  14. Analysis and Design of Tapered Slot Antenna for Ultra-Wideband Applications

    Institute of Scientific and Technical Information of China (English)

    YAO Yuan; CHEN Wenhua; HUANG Bin; FENG Zhenghe; ZHANG Zhijun

    2009-01-01

    The tapered slot antenna,such as Vivaldi,has been widely used due to its ultra-wideband,high gain,simple feed structure,and easy fabrication.However,there is no rigorous analytical theory for this type of antenna.This paper analyzed the metal parts of a tapered slot antenna in a conical coordinate system with the medium analyzed in rectangular coordinates.This mixed mode gave an approximate analytical form for the tapered slot antenna with the field distribution and radiation characteristics.A planar tapered slot antenna was proposed according to the results of the analysis methods.Measured and simulated results demonstrate the antenna performance.The antenna shows good impedance matching over a wide bandwidth of 9 GHz,from 2 GHz to 11 GHz,and good radiation patterns.It is suitable for ultra-wideband applications.

  15. Supercontinuum generation in Ge-doped Y-shaped microstructured tapered fiber

    Energy Technology Data Exchange (ETDEWEB)

    Cascante-Vindas, J [Escuela de Ingenieria Electrica, Universidad de Costa Rica (Costa Rica); DIez, A; Cruz, J L; Andres, M V [Departamento de Fisica Aplicada-ICMUV, Universidad de Valencia (Spain)

    2011-01-01

    We have investigated the generation of supercontinuum in tapered Y-shaped fibers in the nanosecond pump regime. This fiber used to fabricate the tapers has, in addition, a Ge-doped core which enhances the nonlinearity of the material and the Raman gain. The fiber was pumped at 1064 nm in the ns pump regime (0.6 ns pulses and up to 3.2 kW peak power). The taper had a uniform waist of 0.9 {mu}m diameter and 130 mm length, and the adiabatic transitions were 110 mm long. A flat spectrum spanning from 420 nm to 1870 nm was obtained using a single tapered fiber.

  16. Enhanced soliton self-frequency shift in a longitudinally varying taper

    DEFF Research Database (Denmark)

    Judge, A.C.; Bang, Ole; Eggleton, B.J.;

    2009-01-01

    We propose a method for the enhancement of the soliton self-frequency shift in a tapered PCF with a carefully designed waist diameter profile which optimises the dispersion and nonlinearity at the soliton wavelength.......We propose a method for the enhancement of the soliton self-frequency shift in a tapered PCF with a carefully designed waist diameter profile which optimises the dispersion and nonlinearity at the soliton wavelength....

  17. Empirical Optimization of Undulator Tapering at FLASH2 and Comparison with Numerical Simulations

    CERN Document Server

    Mak, Alan; Faatz, Bart; Werin, Sverker

    2016-01-01

    In a free-electron laser equipped with variable-gap undulator modules, the technique of undulator tapering opens up the possibility to increase the radiation power beyond the initial saturation point, thus enhancing the efficiency of the laser. The effectiveness of the enhancement relies on the proper optimization of the taper profile. In this work, a multidimensional optimization approach is implemented empirically in the x-ray free-electron laser FLASH2. The empirical results are compared with numerical simulations.

  18. Experimental and Analytical Investigation of the Shear Strength of Unstiffened Tapered Steel Members

    OpenAIRE

    Redmond, Nicholas A

    2007-01-01

    Tapered beams and columns are often used in single story gable framed steel buildings for reasons of economy. By varying the resistance to bending in similar proportion to the bending moments, more economical structures can be obtained. The beam and column connection, or knee area, is generally subject to the greatest bending moments. It is therefore comprised of the deepest sections of the tapered members, which also possess the least resistance to shear buckling. The web elementâ s str...

  19. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    OpenAIRE

    Milad Farzadi; Mohammadreza Mallakzadeh

    2013-01-01

    Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS), which is a Tapered Interference Fit (TIF) with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tig...

  20. Heater self-calibration technique for shape prediction of fiber tapers

    OpenAIRE

    Sorensen, Heidi L.; Polzik, Eugene S.; Appel, Jurgen

    2013-01-01

    In the production of tapered optical fibers, it is important to control the fiber shape according to application-dependent requirements and to ensure adiabatic tapers. Especially in the transition regions, the fiber shape depends on the heater properties. The axial viscosity profile of the fiber within the heater can, however, be hard to access and is therefore often approximated by assuming a uniform temperature distribution. We present a method for easy experimental calibration of the visco...

  1. Dynamic Response of Tapered Optical Multimode Fiber Coated with Carbon Nanotubes for Ethanol Sensing Application

    OpenAIRE

    Arafat Shabaneh; Saad Girei; Punitha Arasu; Mohd Mahdi; Suraya Rashid; Suriati Paiman; Mohd Yaacob

    2015-01-01

    Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT se...

  2. A tapered undulator experiment at the ELBE far infrared hybrid-resonator oscillator free electron laser

    International Nuclear Information System (INIS)

    A tapered undulator experiment was carried out at the ELBE far-infrared free electron laser (FEL). The oscillator FEL makes use of a hybrid optical resonator. The main motivation was to see whether the presence of a dispersive medium in the form of a waveguide in the resonator has any effect on the outcome. The FEL saturated power and the wavelength shifts have been measured as a function of both positive as well as negative undulator field amplitude tapering. In contrast to the typical high-gain FELs where positive tapering proves beneficial for the output power we observed an improvement of performance at negative taper. During the same experiments we studied the characteristics of the detuning curves. The width of the curves indicates a maximum small signal gain for zero taper while the output peak power increases with negative taper. The saturated power output, the detuning curve characteristics, and the wavelength shifts agrees with the theoretical predictions. Details of the experiment are presented.

  3. Polymer taper bridge for silicon waveguide to single mode waveguide coupling

    Science.gov (United States)

    Kruse, Kevin; Middlebrook, Christopher T.

    2016-03-01

    Coupling of optical power from high-density silicon waveguides to silica optical fibers for signal routing can incur high losses and often requires complex end-face preparation/processing. Novel coupling device taper structures are proposed for low coupling loss between silicon photonic waveguides and single mode fibers are proposed and devices are fabricated and measured in terms of performance. Theoretical mode conversion models for waveguide tapers are derived for optimal device structure design and performance. Commercially viable vertical and multi-layer taper designs using polymer waveguide materials are proposed as innovative, cost-efficient, and mass-manufacturable optical coupling devices. The coupling efficiency for both designs is determined to evaluate optimal device dimensions and alignment tolerances with both silicon rib waveguides and silicon nanowire waveguides. Propagation loss as a function of waveguide roughness and metallic loss are determined and correlated to waveguide dimensions to obtain total insertion loss for the proposed taper designs. Multi-layer tapers on gold-sputtered substrates are fabricated through photolithography as proof-of-concept devices and evaluated for device loss optimization. Tapered waveguide coupling loss with Si WGs (2.74 dB) was experimentally measured with high correlation to theoretical results.

  4. 2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla

    Directory of Open Access Journals (Sweden)

    Shrikar R Desai

    2013-01-01

    Full Text Available Aim: The aim of the study is to evaluate the influence implant length on stress distribution at bone implant interface in single immediately loaded implants when placed in D4 bone quality. Materials and Methods: A 2-dimensional finite element models were developed to simulate two types of implant designs, standard 3.75 mm-diameter tapered body implants of 6 and 10 mm lengths. The implants were placed in D4 bone quality with a cortical bone thickness of 0.5 mm. The implant design incorporated microthreads at the crestal part and the rest of the implant body incorporated Acme threads. The Acme thread form has a 29° thread angle with a thread height half of the pitch; the apex and valley are flat. A 100 N of force was applied vertically and in the oblique direction (at an angle of 45° to the long axis of the implants. The respective material properties were assigned. Micro-movements and stresses at the bone implant interface were evaluated. Results: The results of total deformation (micro-movement and Von mises stress were found to be lower for tapered long implant (10 mm than short implant (6 mm while using both vertical as well as oblique loading. Conclusion: Short implants can be successfully placed in poor bone quality under immediate loading protocol. The novel approach of the combination of microthreads at the crestal portion and acme threads for body portion of implant fixture gave promising results.

  5. Effects of intensified training and taper on immune function

    Directory of Open Access Journals (Sweden)

    Elena Papacosta

    2013-03-01

    Full Text Available Although resting immune function is not very different in athletes compared with non-athletes periods of intensified training (overreaching in already well trained athletes can result in a depression of immunity in the resting state. Illness-prone athletes appear to have an altered cytokine response to antigen stimulation and exercise. Having low levels of salivary IgA secretion also makes athletes more susceptible to upper respiratory tract infections. Overtraining is associated with recurrent infections and immunodepression is common, but immune functions do not seem to be reliable markers of impending overtraining. There are several possible causes of the diminution of immune function associated with periods of heavy training. One mechanism may simply be the cumulative effects of repeated bouts of intense exercise (with or without tissue damage with the consequent elevation of stress hormones, particularly glucocorticoids such as cortisol, causing temporary inhibition of TH-1 cytokines with a relative dampening of the cell-mediated response. When exercise is repeated frequently there may not be sufficient time for the immune system to recover fully. Tapering has been described as a gradual reduction in the training load which allows the recovery of physiological capacities that were impaired by previous intensive training and permits further training-induced adaptations to occur accompanied by competition performance enhancements. The majority of the studies that have examined the recovery of immunoendocrine responses during 1-3 week tapers in trained athletes have mainly reported enhanced performance, often accompanied by increased anabolic activity, reduced physiological stress and restoration of mucosal immunity and immune function.Quando se compara a função imune, em repouso, de atletas e não atletas, não se verificam grandes diferenças. Porém, períodos de treinamento intensificado ("overreaching" em atletas bem treinados podem

  6. Characterization of a high-power tapered semiconductor amplifier system

    CERN Document Server

    Voigt, D; Spreeuw, R J C; Van Linden van den Heuvell, H B

    2001-01-01

    We have characterized a semiconductor amplifier laser system which provides up to 200mW output after a single-mode optical fiber at 780nm wavelength. The system is based on a tapered semiconductor gain element, which amplifies the output of a narrow-linewidth diode laser. Gain and saturation are discussed as a function of operating temperature and injection current. The spectral properties of the amplifier are investigated with a grating spectrometer. Amplified spontaneous emission (ASE) causes a spectral background with a width of 4nm FWHM. The ASE background was suppressed to below our detection limit by a proper choice of operating current and temperature, and by sending the light through a single-mode optical fiber. The final ASE spectral density was less than 0.1nW/MHz, i.e. less than 0.2 % of the optical power. Related to an optical transition linewidth of $\\Gamma/2\\pi=6$ MHz for rubidium, this gives a background suppression of better than -82dB. An indication of the beam quality is provided by the fibe...

  7. Columnar mesophase from non-symmetrical tapered hydrazide derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Bai Binglian, E-mail: baibinglian@jlu.edu.cn [Key Laboratory for Automobile Materials (JLU), Ministry of Education, Institute of Materials Science and Engineering, Jilin University, Changchun 130012 (China); College of Physics, Jilin University, Changchun 130012 (China); Zhao Chengxiao; Wang Haitao; Ran Xia [Key Laboratory for Automobile Materials (JLU), Ministry of Education, Institute of Materials Science and Engineering, Jilin University, Changchun 130012 (China); Wang Dan [College of Physics, Jilin University, Changchun 130012 (China); Li Min, E-mail: minli@mail.jlu.edu.cn [Key Laboratory for Automobile Materials (JLU), Ministry of Education, Institute of Materials Science and Engineering, Jilin University, Changchun 130012 (China)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We aimed at developing new liquid-crystalline hydrazide derivatives. Black-Right-Pointing-Pointer The columnar mesophases are observed in these hydrazide derivatives. Black-Right-Pointing-Pointer Experimental results revealed that the amide protons of the central hydrazide group participated in intermolecular double hydrogen bonds based on C=O and -NH in mesophase. Black-Right-Pointing-Pointer The intermolecular hydrogen-bonding interaction among dihydrazine units is the main driving force to form the mesophase. - Abstract: A new series of liquid-crystalline tapered hydrazide derivatives with an amino head group, e.g. N-(3,4,5-trialkoxylbenzoyl)-N Prime -(4 Prime -aminobenzoyl) hydrazine (Dn, where n is the number of carbon atoms in the alkyl chains, n = 6, 8, 16), were designed and synthesized. Results of {sup 1}H NMR diluting experiment and FTIR spectroscopy revealed that the amide protons of the central hydrazide group in Dn participated in intermolecular double hydrogen bonds based on C=O and -NH in liquid crystalline phase. Investigations on the liquid crystalline properties showed that the D6 exhibited non-mesophase, D8 exhibited monotropic hexagonal columnar mesophase, while D16 exhibited enantiotropic oblique columnar mesophase with increasing the length of the terminal chains.

  8. Analysis of elastic stiffness for the leaf type holddown spring assembly with uniformly tapered thickness considering the point of taper runout

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Nam [Korea Atomic Energy Research Institute, Daeduk (Korea, Republic of)

    1996-04-01

    In the case that the point of taper runout is outside the bent region of spring base, a formula to evaluate the elastic stiffness of the leaf type holddown spring (HDS) assembly with uniformly tapered thickness from t{sub 0} to t{sub 1} (t{sub 0}>t{sub 1}) has been analytically derived by applying the engineering beam theory and Casiliano`s theorem based on strain energy. It has found that taper runouts for the 14x14 and 17x17 type KOFA HDS were up to 2.2 mm and effects on their elastic stiffnesses were about 3.70%, and that the elastic stiffness of the HDS was mainly caused by bending moment. And in addition, for the HDS designed/manufactured from Westinghouse, elastic stiffnesses from the derived formula were in good agreement with those from the Westinghouse`s empirical formula. Therefore, the derived formula could be applicable to evaluating the elastic stiffness of any HDS with tapered thickness only with the informations of the geometric data and material properties of leaf springs regardness of the manufacturing companies. 11 tabs., 4 figs., 25 refs. (Author) .new.

  9. Lumped-element model of a tapered transmission line for impedance matching in a pulsed power system

    Science.gov (United States)

    Lee, Kun-A.; Ko, Kwang-Cheol

    2016-07-01

    In a pulsed power system, impedance matching is one of the significant factors for increasing the efficiency of the system. One of the most general methods for impedance matching is to use a tapered transmission line. Because the characteristics of a tapered transmission line are changed continuously according to its position, modeling the tapered transmission line by using lumped elements is difficult. In this study, we investigated a tapered transmission line to match the impedance of power supply to that of a load by using lumped elements especially in a pulsed power system. In modeling the tapered transmission line, we used the concept of a transmission, and we introduced an efficient modeling method. We propose a simulation model based on the investigation results. The results of the study will be useful for research on tapered transmission lines.

  10. Fatigue Life Methodology for Tapered Composite Flexbeam Laminates

    Science.gov (United States)

    Murri, Gretchen B.; O''Brien, T. Kevin; Rousseau, Carl Q.

    1997-01-01

    The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to nonlinear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending loads. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse flexbeam tip-displacement and flapping angle. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

  11. Silicon knife-edge taper waveguide for ultralow-loss spot-size converter fabricated by photolithography

    Science.gov (United States)

    Takei, R.; Suzuki, M.; Omoda, E.; Manako, S.; Kamei, T.; Mori, M.; Sakakibara, Y.

    2013-03-01

    For ultralow-loss and polarization-insensitive spot-size converters (SSCs) on a silicon platform, we propose and demonstrate a silicon knife-edge taper waveguide with a gradual decrease in height as well as width toward the taper end. The taper was fabricated using a double-patterning method involving i-line stepper photolithography and angled sidewall dry-etching. The SSC, with the knife-edge taper covered with a polymer secondary core, exhibited mode conversion losses of 0.35 and 0.21 dB for transverse electric-like and transverse magnetic-like modes, respectively.

  12. Mechanically induced long period fiber gratings on single mode tapered optical fiber for structure sensing applications

    Science.gov (United States)

    Pulido-Navarro, María. G.; Marrujo-García, Sigifredo; Álvarez-Chávez, José A.; Velázquez-González, Jesús S.; Martínez-Piñón, Fernando; Escamilla-Ambrosio, Ponciano J.

    2015-08-01

    The modal characteristics of tapered single mode optical fibers and its strain sensing characteristics by using mechanically induced long period fiber gratings are presented in this work. Both Long Period Fiber Gratings (LPFG) and fiber tapers are fiber devices that couple light from the core fiber into the fiber cladding modes. The mechanical LPFG is made up of two plates, one flat and the other grooved. For this experiment the grooved plate was done on an acrylic slab with the help of a computer numerical control machine. The manufacturing of the tapered fiber is accomplished by applying heat using an oxygen-propane flame burner and stretching the fiber, which protective coating has been removed. Then, a polymer-tube-package is added in order to make the sensor sufficiently stiff for the tests. The mechanical induced LPFG is accomplished by putting the tapered fiber in between the two plates, so the taper acquires the form of the grooved plate slots. Using a laser beam the transmission spectrum showed a large peak transmission attenuation of around -20 dB. The resultant attenuation peak wavelength in the transmission spectrum shifts with changes in tension showing a strain sensitivity of 2pm/μɛ. This reveals an improvement on the sensitivity for structure monitoring applications compared with the use of a standard optical fiber. In addition to the experimental work, the supporting theory and numerical simulation analysis are also included.

  13. An experimental and analytical evaluation of the tapered tension-torsion strap concept

    Science.gov (United States)

    Louie, Alexander

    1988-01-01

    A new free-tip rotor moment controller designed to increase torque output (a restoring moment) was proposed. The controller would be used as a retention device for the freely pitching tip of a helicopter rotor. The new design featured a tapered tension-torsion strap instead of the previously used parellel strap. A tapered strap has a larger separation between the tension wires at the retention end than at the oscillating end; separation is equal at both ends for a parallel strap. A simple dynamic analysis was developed and an experiment performed to evaluate this tapered strap concept. The test results indicated that the torsional spring stiffness of the strap, represented by a torsional pendulum, increased with the amount of taper. The predicted dynamic characteristics of the pendulum also confirmed this observation and correlated reasonably well with the experimental results. It could be concluded from the experimental and analytical results that the tapered strap accomplished increased torque output when compared to the parellel strap.

  14. Investigation on single taper-based all-solid photonic bandgap fiber modal interferometers.

    Science.gov (United States)

    Li, Jie; Geng, Mengmei; Sun, Li-Peng; Fan, Pengcheng; Liu, Bo; Guan, Bai-Ou

    2016-04-18

    We demonstrate a single taper-based all-solid photonic bandgap (AS-PBG) fiber modal interferometer that consists of a central tapered fiber region connected to the untapered via two abrupt transitions. Modal interference is given by superimposing the bandgap-guided fundamental core mode with a lower effective index and a specific index-guided cladding supermode with a higher effective index. A series of interferometers with taper diameter of 50μm ~60μm and device length of ~3mm are fabricated and studied in contrast to the conventional counterparts. The temperature coefficient of the interferometer is closely determined by the fraction of the cladding supermode energy localized within the index-raised regions of the fiber. The refractive index (RI) responsivities associated to fiber taper sizes are investigated. The measured maximal RI sensitivity is ~3512.36nm/RIU at the taper diameter of 50μm around RI = 1.423. This research gives a deep understanding to the modal-interferometric AS-PBG structure, which we believe to be valuable for the future application of the related device. PMID:27137292

  15. Experimental study of friction of tapered surfaces in keyless propeller. 2{sup nd} report. Effects of taper machining error and surface roughness; Keyless propeller ni okeru taper sesshokumen no masatsu ni kansuru-jikken. 2: taper kako gosa oyobi hyomen arasa no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kawazoe, T.; Ura, A.; Nakashima, A. [Nagasaki Univ. (Japan)] Nishikido, S. [Mitsubishi Heavy Industries Ltd., Nagasaki (Japan). Nagasaki Shipyard and Engine Works

    1997-12-01

    About 25 years have passed since the development of the keyless propeller, however, recently, torque slip problem is cause in keyless propeller. In the previous report, from one of this factor, experiment was carried out concentrating on the friction behavior at elasto-plastic deformation region. This time, effect of taper machining error and surface roughness, that are the problems while manufacturing keyless propeller and axes on the friction behavior of taper contact surface was studied using a new grip coefficient. As a result, the friction behavior (specially the grip coefficient) during the pushing of keyless propeller was effected greatly by the taper machining error rather than surface roughness and the precision of the taper machining of axis and boss become important. Further, taper machining error is not considered in the design calculation of push-up distance, therefore, if low grip coefficient region is caused in push-up operation, it is preferred that push-up must be carried out up to the decided push-up distance excluding this. These were the clarified things. 6 refs., 10 figs.

  16. Thermoelectric generator performance analysis: Influence of pin tapering on the first and second law efficiencies

    International Nuclear Information System (INIS)

    Highlights: • Double tapering of thermoelectric elements improves first and second law efficiency. • Pin geometric feature maximizing device output work does not maximize thermal efficiency. • Pin geometric feature maximizing first law efficiency slight alters for maximum second law efficiency. • External resistance and operating temperature ratios influence design configuration of thermoelectric generator. - Abstract: Thermoelectric generators are the important candidates for clean energy conversion from the waste heat; however, their low efficiency limits the practical applications of the devices. Tailoring the geometric configuration of the device in line with the operating conditions can improve the device performance. Consequently; in the present study, the influence of the pin geometric configuration on the thermoelectric generator performance is investigated. The dimensionless tapering parameter is introduced and its effect on the first and second law efficiencies is examined for various operating conditions including the external load resistance and the temperature ratio. It is found that the first and second law efficiencies are significantly influenced by the pin geometry. The dimensionless tapering parameter (a), increasing tapering of the thermoelectric pins, within the range of 2 ⩽ a ⩽ 4 results in improved first and second law efficiencies. However, the dimensionless tapering parameter maximizing the first and second law efficiencies does not maximize the device output power. This behavior is associated with the external load resistance which has a considerable influence on the device output power such that increasing external load resistance lowers the device output power

  17. On the use of tapered bismuth germanate crystals in positron emission tomography

    International Nuclear Information System (INIS)

    An analytical model of gamma ray transport within the detectors of a positron camera, based on exponential absorption, has been developed and verified experimentally. The model has been used to study the intrinsic resolution obtained with scintillation detectors that have had their front corners removed. It is concluded that for crystals greater than 0.8 cm wide, tapering the face of the detector results in improved uniformity of resolution. Thus it is useful for medium and low resolution scanners. In these cases, it has been found that the loss in sensitivity resulting from the use of tapered crystals is less than that which occurs when septa are placed between crystals to achieve comparable uniformity of resolution. It has also been established that, in some instances, reducing the length of the detectors results in a more uniform resolution than that obtained with tapered crystals, although this leads to a loss in ring sensitivity and an increase in the detected scatter fraction. (orig.)

  18. About the role of phase matching between a coated microsphere and a tapered fiber: experimental study.

    Science.gov (United States)

    Ristić, Davor; Rasoloniaina, Alphonse; Chiappini, Andrea; Féron, Patrice; Pelli, Stefano; Conti, Gualtiero Nunzi; Ivanda, Mile; Righini, Giancarlo C; Cibiel, Gilles; Ferrari, Maurizio

    2013-09-01

    Coatings of spherical optical microresonators are widely employed for different applications. Here the effect of the thickness of a homogeneous coating layer on the coupling of light from a tapered fiber to a coated microsphere has been studied. Spherical silica microresonators were coated using a 70SiO(2)- 30HfO(2) glass doped with 0.3 mol% Er(3+) ions. The coupling of a 1480 nm pump laser inside the sphere has been assessed using a tapered optical fiber and observing the 1530-1580 nm Er(3+) emission outcoupled to the same tapered fiber. The measurements were done for different coating thicknesses and compared with theoretical calculations to understand the relationship of the detected signal with the whispering gallery mode electric field profiles. PMID:24103968

  19. Temperature sensing on tapered single mode fiber using mechanically induced long period fiber gratings

    Science.gov (United States)

    Marrujo-García, Sigifredo; Velázquez-González, Jesús Salvador; Pulido-Navarro, María. Guadalupe; González-Ocaña, Ernesto; Mújica-Ascencio, Saúl; Martínez-Piñón, Fernando

    2015-09-01

    The modeling of a temperature optical fiber sensor is proposed and experimentally demonstrated in this work. The suggested structure to obtain the sensing temperature characteristics is by the use of a mechanically induced Long Period Fiber Grating (LPFG) on a tapered single mode optical fiber. A biconical fiber optic taper is made by applying heat using an oxygen-propane flame burner while stretching the single mode fiber (SMF) whose coating has been removed. The resulting geometry of the device is important to analyze the coupling between the core mode to the cladding modes, and this will determine whether the optical taper is adiabatic or non-adiabatic. On the other hand, the mechanical LPFG is made up of two plates, one grooved and other flat, the grooved plate was done on an acrylic slab with the help of a computerized numerical control machine (CNC). In addition to the experimental work, the supporting theory is also included.

  20. Optical microscope and tapered fiber coupling apparatus for a dilution refrigerator.

    Science.gov (United States)

    MacDonald, A J R; Popowich, G G; Hauer, B D; Kim, P H; Fredrick, A; Rojas, X; Doolin, P; Davis, J P

    2015-01-01

    We have developed a system for tapered fiber measurements of optomechanical resonators inside a dilution refrigerator, which is compatible with both on- and off-chip devices. Our apparatus features full three-dimensional control of the taper-resonator coupling conditions enabling critical coupling, with an overall fiber transmission efficiency of up to 70%. Notably, our design incorporates an optical microscope system consisting of a coherent bundle of 37,000 optical fibers for real-time imaging of the experiment at a resolution of ∼1 μm. We present cryogenic optical and optomechanical measurements of resonators coupled to tapered fibers at temperatures as low as 9 mK. PMID:25638072

  1. New stem taper functions for 12 Saskatchewan timber species. Information report No. -X-338

    Energy Technology Data Exchange (ETDEWEB)

    Gal, J.

    1994-12-31

    The Saskatchewan Provincial Timber Inventory system uses a combined-variable equation for calculating tree volumes and taper functions for calculating log volumes. In the past few years, there have been concerns that the system might underestimate the volumes of small-sized trees. To address this, additional data were collected for small trees and refitting of the old taper function was initiated. This study screened all available data; chose new taper functions of potential usefulness for the 12 timber species in the province; fit these functions to the data; and through analysis of their fit, selected the function or functions that provide the best fit and the most accurate volume estimates over the range of size classes present. The species used were white spruce, black spruce, jack pine, lodgepole pine, balsam fir, tamarack larch, trembling aspen, black poplar, white birch, green ash, Manitoba maple, and white elm.

  2. A study of multi-trapping of tapered-tip single fiber optical tweezers

    International Nuclear Information System (INIS)

    We develop a pair of tapered-tip single fiber optical tweezers, and study its multi-trapping characteristic. The finite difference time domain method is employed to simulate the trapping force characteristic of this pair of single fiber optical tweezers, and the results show that the number of trapped particles depends on the refractive index and the size of the particles. The trapping force of this pair of tapered-tip single fiber optical tweezers is calibrated by the experimental method, and the experimental results are consistent with the theoretical calculation results. The multi-trapping capability realized by the tapered-tip single fiber optical tweezers will be practical and useful for applications in biomedical research fields. (interdisciplinary physics and related areas of science and technology)

  3. Tailored dispersion profile in controlling optical solitons in a tapered parabolic index fiber

    Science.gov (United States)

    Prakash, S. Arun; Malathi, V.; Mani Rajan, M. S.

    2016-03-01

    We investigate the soliton dynamics in tapered parabolic index fibers via symbolic computation for a variety of dispersion profiles to inspect how a specific dispersion profile controls the optical soliton. By means of AKNS procedure, Lax pair is constructed for nonlinear Schrödinger equation with variable coefficients. Using obtained Lax pair, multi-soliton solutions are generated via Darboux transformation technique. Using multi-soliton solutions, soliton dynamics in tapered parabolic index fiber with the hyperbolic, Gaussian, exponential, and linear profiles are discussed. Results obtained in this study will be of certain potential application on construction of the nonlinear optical devices by soliton control. Results obtained in this study will be of certain value to the studies on the propagation and application of the soliton in the tapered parabolic index fiber and dispersion-managed fiber system.

  4. Generation of single-frequency tunable green light in a coupled ring tapered diode laser cavity

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Petersen, Paul Michael

    2013-01-01

    the broad wavelength range from 1049 nm to 1093 nm and the beam propagation factor is improved from M2 = 2.8 to below 1.1. The laser frequency is automatically locked to the cavity resonance frequency using optical feedback. Furthermore, we show that this adaptive external cavity approach leads to......We report the realization of a tapered diode laser operated in a coupled ring cavity that significantly improves the coherence properties of the tapered laser and efficiently generates tunable light at the second harmonic frequency. The tapered diode laser is tunable with single-frequency output in...... efficient frequency doubling. More than 500 mW green output power is obtained by placing a periodically poled LiNbO3 crystal in the external cavity. The single frequency green output from the laser system is tunable in the 530 nm to 533 nm range limited by the LiNbO3 crystal. The optical to optical...

  5. High-power 1550 nm tapered DBR lasers fabricated using soft UV-nano-imprint lithography

    Science.gov (United States)

    Viheriälä, Jukka; Aho, Antti T.; Mäkelä, Jaakko; Salmi, Joel; Virtanen, Heikki; Leinonen, Tomi; Dumitrescu, Mihail; Guina, Mircea

    2016-03-01

    Paper reports the DBR-RWG surface grating design, the fabrication process, and the output characteristics of tapered DBR laser diodes for the applications, like for example LIDAR and range finding, that require eye-safe high-power single-mode coherent light sources. The fabricated regrowth-free DBR AlGaInAs/InP lasers exhibited a CW output power as high as 560 mW in single-mode operation at room temperature. At maximum output power the SMSR was 38 dB, proving the excellent behavior of the surface gratings. The tapered section enabled scaling the maximum CW power at room temperature from 125 mW to 560 mW, by increasing its length from 0.5 mm to 4.0 mm. The paper discusses the limitations and performance variation associated to the power scaling by using the tapered section length as a scaling parameter.

  6. Ultrathin fiber-taper coupling with nitrogen vacancy centers in nanodiamonds at cryogenic temperatures.

    Science.gov (United States)

    Fujiwara, Masazumi; Zhao, Hong-Quan; Noda, Tetsuya; Ikeda, Kazuhiro; Sumiya, Hitoshi; Takeuchi, Shigeki

    2015-12-15

    We demonstrate cooling of ultrathin fiber tapers coupled with nitrogen vacancy (NV) centers in nanodiamonds to cryogenic temperatures. Nanodiamonds containing multiple NV centers are deposited on the subwavelength 480-nm-diameter nanofiber region of fiber tapers. The fiber tapers are successfully cooled to 9 K using our home-built mounting holder and an optimized cooling speed. The fluorescence from the nanodiamond NV centers is efficiently channeled into a single guided mode and shows characteristic sharp zero-phonon lines (ZPLs) of both neutral and negatively charged NV centers. The present nanofiber/nanodiamond hybrid systems at cryogenic temperatures can be used as NV-based quantum information devices and for highly sensitive nanoscale magnetometry in a cryogenic environment. PMID:26670490

  7. Hydrolysis of Olive Oil with Immobilized Lipase in a Tapered Column Reactor

    Institute of Scientific and Technical Information of China (English)

    杨伯伦; 赵国胜; 林宏业

    2003-01-01

    Lipase was immobilized in ion exchange resin and then used in the hydrolysis of olive oil to produce fatty acids and glycerol. The time course of hydrolysis of olive oil was investigated in a stirred tank reactor using both of the free and immobilized lipases to find the yield of activity of immobilized enzyme. Continuous hydrolysis of olive oil was also carried out in a tapered column reactor and a cylindrical column reactor with a bottom ID of 10 mm at different upward flow rates. It can be known from experimental results that the degree of hydrolysis of olive oil in the tapered column reactor is moderately better than that in the cylindrical column reactor, the pressure drop in the tapered column reactor is much smaller than that in the cylindrical column reactor.

  8. An efficient method for supercontinuum generation in dispersion-tailored Lead-silicate fiber taper

    Science.gov (United States)

    Chen, Z.; Ma, S.; Dutta, N. K.

    2010-08-01

    In this paper we theoretically study the broadband mid-IR supercontinuum generation (SCG) in a lead-silicate microstructured fiber (the glass for simulation is SF57). The total dispersion of the fiber can be tailored by changing the core diameter of the fiber so that dispersion profiles with two zero dispersion wavelengths (ZDWs) can be obtained. Numerical simulations of the SCG process in a 4 cm long SF57 fiber/fiber taper seeded by femto-second pulses at telecommunications wavelength of 1.55 µm are presented. The results show that a fiber taper features a continuous shift of the longer zero dispersion wavelength. This extends the generated continuum to a longer wavelength region compared to fibers with fixed ZDWs. The phase-matching condition (PMC) is continuously modified in the fiber taper and the bandwidth of the generated dispersive waves (DWs) is significantly broadened.

  9. Analysis & Design of the Coupling Efficiency using Ion Exchange Tapered Waveguide

    Directory of Open Access Journals (Sweden)

    A. Agrebi

    2014-01-01

    Full Text Available This paper reports modeling and simulation of low-loss coupling between two different sections standard optical fiber. This Technique will use a Tapered waveguide made by ion exchange technique on glass substrate. The principle of ion exchange technology, to make a planar waveguides on glass, is explained. So we have developed a program that simulates diffusion with or without external electric field assistance to manufacture diffused waveguides. On the other hand, the numerical method used to compute the propagation in those waveguides, is the finite-difference vector beam propagation method (FD-VBPM. As an application, concave and convex ion exchange (IEx Tapers obtained by varying the parameter α, are analyzed. Length, input and output cross-section of this component, are also varied in order to investigate the effects of geometric parameters on coupling efficiency. The calculated coupling losses are reasonable and acceptable and prove that using convex Tapered waveguide is recommended.

  10. High power, high brightness Al-free active region tapered lasers at 915 nm

    Science.gov (United States)

    Hassiaoui, I.; Michel, N.; Lecomte, M.; Parillaud, O.; Calligaro, M.; Krakowski, M.

    2006-04-01

    To achieve high power and high brightness, we have developed tapered diode lasers based on an Al-free active region at 915 nm. The material structure was grown by MOCVD (Metallorganic Chemical Vapor Deposition). It shows very low internal losses of only 0.5 cm -1, a very low transparency current density of 86 A/cm2, an excellent internal quantum efficiency of 86%, and a high characteristic temperature T 0 of 171 K. Based on these good results, at first, we have realised index-guided tapered lasers (IG1) with a narrow output width and a narrow taper angle, which deliver 1 W CW, together with an M2 beam quality parameter of 2.9 at 1/e2, and a narrow divergence angle in the slow axis of 5.1° FWHM and 7.5° at 1/e2. We have also fabricated new index-guided tapered lasers with a Clarinet shape, which were recently proposed to achieve high brightness together with a very narrow divergence angle. The Clarinet lasers deliver 0.6W CW, together with an excellent M2 beam quality factor of 1.2 at 1/e2, and a very narrow divergence angle in the slow axis of only 2.5° FWHM, and 3.9° at 1/e2, which is stable with current. These very narrow divergences are very advantageous for the collective coupling of tapered bars into optical fibers. In this work we have also investigated the influence of taper length on the output power and beam quality.

  11. First Principles Studies of Tapered Silicon Nanowires: Fundamental Insights and Practical Applications

    Science.gov (United States)

    Wu, Zhigang

    2008-03-01

    Nanowires (NWs) are often observed experimentally to be tapered rather than straight-edged, with diameters (d) shrinking by as much as 1 nm per 10 nm of vertical growth. Previous theoretical studies have examined the electronic properties of straight-edged nanowires (SNWs), although the effects of tapering on quantum confinement may be of both fundamental and practical importance. We have employed ab initio calculations to study the structural and electronic properties of tapered Si NWs. As one may expect, tapered nanowires (TNWs) possess axially-dependent electronic properties; their local energy gaps vary along the wire axis, with the largest gap occurring at the narrowest point of the wire. In contrast to SNWs, where confinement tends to shift valence bands more than conduction bands away from the bulk gap, the unoccupied states in TNWs are much more sensitive to d than the occupied states. In addition, tapering causes the band-edge states to be spatially separated along the wire axis, a consequence of the interplay between a strong variation in quantum confinement strength with diameter and the tapering-induced charge transfer. This property may be exploited in electronic and optical applications, for example, in photovoltaic devices where the separation of the valence and conduction band states could be used to transport excited charges during the thermalization process. In order to gain insight into TNW photovoltaic properties, we have also carried out calculations of the dipole matrix elements near the band edges as well as the role of metal contacts on TNW electronic properties. Finally, a combination of ab initio total energy calculations and classical molecular dynamics (MD) simulations are employed to suggest a new technique for bringing nanoscale objects together to form ordered, ultra high-aspect ratio nanowires. This work was supported in part by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  12. Influence of convective conditions in radiative peristaltic flow of pseudoplastic nanofluid in a tapered asymmetric channel

    Science.gov (United States)

    Hayat, T.; Iqbal, Rija; Tanveer, Anum; Alsaedi, A.

    2016-06-01

    This paper looks at the influences of magnetohydrodynamics (MHD) and thermal radiation on peristaltic transport of a pseudoplastic nanofluid in a tapered asymmetric channel. The tapered channel walls satisfy convective boundary conditions. The governing equations for the balance of mass, momentum, temperature and volume fraction for pseudoplastic nanofluid are first formulated and then utilized for long wavelength and small Reynolds number considerations. Effects of involved parameters on the flow characteristics have been plotted and examined. It is observed that the heat transfer Biot number shows a dual behavior on the temperature of nanofluid particles whereas the mass transfer Biot number with its increasing values enhances the fluid temperature.

  13. About the role of phase matching between a coated microsphere and a tapered fiber: experimental study

    OpenAIRE

    Ristic, Davor; Rasoloniaina, Alphonse; Chiappini, Andrea; Féron, Patrice; Pelli, Stefano; Nunzi-Conti, Gualtiero; Ivanda, Mile; Righini, Giancarlo; Cibiel, Gilles; Ferrari, Maurizio

    2013-01-01

    Coatings of spherical optical microresonators are widely employed for different applications. Here the effect of the thickness of a homogeneous coating layer on the coupling of light from a tapered fiber to a coated microsphere has been studied. Spherical silica microresonators were coated using a 70SiO2 - 30HfO2 glass doped with 0.3 mol% Er3+ ions. The coupling of a 1480 nm pump laser inside the sphere has been assessed using a tapered optical fiber and observing the 1530-1580 nm Er3+ emissi...

  14. Intensity-measurement bend sensors based on periodically tapered soft glass fibers

    OpenAIRE

    Wang, Y.; Richardson, D. J.; Brambilla, G; Feng, X.; Petrovich, M.N.; Ding, M.; Song, Z.(Central China Normal University, Wuhan, China)

    2011-01-01

    We demonstrate a novel technique for tapering periodically an all-solid soft glass fiber, consisting of two types of lead silicate glasses, by the use of a focused CO2 laser beam and investigate the bend sensing applications of the periodically-tapered soft glass fiber. Such a soft glass fiber with periodic microtapers could be used to develop promising bend sensors with a sensitivity of -27.75 ?W/m^-1 by means of measuring the bend-induced change of light intensity. The proposed bend sensor ...

  15. Widely Tunable High-Power Tapered Diode Laser at 1060 nm

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Sumpf, Bernd; Erbert, Götz;

    2011-01-01

    We report a large tuning range from 1018 to 1093 nm from a InGaAs single quantum-well 1060-nm external cavity tapered diode laser. More than 2.5-W output power has been achieved. The tuning range is to our knowledge the widest obtained from a high-power InGaAs single quantum-well tapered laser...... operating around 1060 nm. The light emitted by the laser has a nearly diffraction limited beam quality and a narrow linewidth of less than 6 pm everywhere in the tuning range....

  16. Interlaminar stresses and fracture behavior in thickness-tapered composite laminates

    Science.gov (United States)

    He, Kan

    Design and manufacture of a variable thickness composite laminate such as a helicopter yoke involves tapering the laminate by dropping individual plies at discrete internal locations, in order to tailor the stiffness of the laminate. The ply drop in the laminate creates large interlaminar stresses and initiates delamination. Therefore, there is a necessity to investigate the fundamental failure mechanisms and controlling parameters that account for the delamination mode of failure in tapered laminates. In this thesis, a numerical and experimental study on interlaminar stresses and delamination in tapered laminates is presented, including a critical and comprehensive review on earlier works on this type of structure. Numerical analyses performed involved development of partial hybrid stress finite elements needed to enhance computational efficiency, and development of a physical concept-based modified shear-lag model that is based on the essential assumptions that both plies and resin layers are treated as carriers of tensile stress and also to act as stress-transfer media. Experimental analysis was attempted to assess the accuracy of the numerical predictions. For this purpose, tapered NCT-301 Graphite/Epoxy specimens were manufactured using a ply in-fill technique for the cured consolidation and tested under quasi-static uniaxial tension. To perform strength and delamination analyses of the tapered laminate, the laminate was modeled as a generalized plane deformation problem, where all the variables involved in the model are independent of the coordinate system. Also quasi-three dimensional partial hybrid finite elements were used to quantify the analysis. In addition to the plies, the inter-ply resin at the critical ply interface was also modeled in order to have direct and realistic interlaminar responses. Stress-based criteria that have proved to be effective in determination of critical location and load of delamination onset were utilized in this study to

  17. Evaluation on Tensile Strength and Applicability of Tapered Rolled Thread Coupler

    International Nuclear Information System (INIS)

    Various diameters of reinforcing bars, ASTM A 615 Grade 60 11, 14, and 18, are used for construction of Nuclear Power Plant structures. But due to the large diameter of these rebar, placing rebar is difficult. This study suggests a new tapered rolled thread coupler which have improved workability and fastening force. To evaluate tensile strength and applicability, the tensile test are conducted and static load-carrying capacity of rolled thread coupler are evaluated. In the both tensile tests and column tests, the good agreement of load-carrying capacity are shown. Therefore the proposed tapered rolled thread coupler can be applied to the NPP to replace conventional coupler

  18. Low-loss deposition of solgel-derived silica films on tapered fibers.

    Science.gov (United States)

    Kakarantzas, G; Leon-Saval, S G; Birks, T A; Russell, P St J

    2004-04-01

    Films of porous silica are deposited on the uniform waists of tapered fibers in minutes by a modified solgel dip coating method, inducing less than 0.2 dB of loss. The coated tapers are an ideal platform for realizing all-fiber devices that exploit evanescent-field interactions with the deposited porous film. As an example we demonstrate structural long-period gratings in which a periodic index variation in the film arises from the porosity variation produced by spatially varying exposure of the waist to a scanned CO2 laser beam. The long period grating is insensitive to temperature up to 800 degrees C. PMID:15072361

  19. ¿Cómo ajustar la carga de entrenamiento? : proceso de tapering en baloncesto

    OpenAIRE

    Muñoz Diez, Rubén

    2014-01-01

    El objetivo del trabajo es determinar cómo se puede ajustar la carga de entrena-miento durante el periodo competitivo en baloncesto. Se realiza una revisión bibliográ-fica del tapering para determinar cuáles son las variables más importantes a utilizar en una puesta a punto. Tras esto se adjuntan varias propuestas en función de la semana competitiva y se pretende aclarar si es factible la utilización de un tapering en deportes con un periodo de competición muy concentrado.

  20. Tapered Simplified Modal Method for Analysis of Non-rectangular Gratings

    CERN Document Server

    Li, Shuai; Barbastathis, George

    2016-01-01

    The Simplified Modal Method (SMM) provides a quick and intuitive way to analyze the performance of gratings of rectangular shapes. For non-rectangular shapes, a version of SMM has been developed, but it applies only to the Littrow-mounting incidence case and it neglects reflection. Here, we use the theory of mode-coupling in a tapered waveguide to improve SMM so that it applies to non-rectangular gratings at arbitrary angles of incidence. Moreover, this new 'Tapered Simplified Modal Method' (TSMM) allows us to properly account for reflected light. We present here the analytical development of the theory and numerical simulations, demonstrating the validity of the method.

  1. 77 FR 2031 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2012-01-13

    ... Unfinished From the People's Republic of China: Initiation of Antidumping Duty New Shipper Review, 76 FR... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... shipper review of the antidumping duty order on tapered roller bearings and parts thereof, finished...

  2. 76 FR 6397 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2011-02-04

    ... China, 52 FR 22667 (June 15, 1987) (``Order''). On December 23, 2010, pursuant to section 751(a)(2)(B)(i... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the... shipper review (``NSR'') of the antidumping duty order on tapered roller bearings (``TRBs'') from...

  3. Tapered and linearly chirped fiber Bragg gratings with co-directional and counter-directional resultant chirps

    Science.gov (United States)

    Osuch, Tomasz

    2016-05-01

    A method of spectral width tailoring of tapered fiber Bragg gratings is theoretically analyzed and experimentally verified. This concept is based on inscription grating structures in which synthesis of chirps comes from both taper profile and a linearly chirped phase mask used for grating inscription. It is shown that under UV exposure and depending on the orientation of the optical fiber taper relative to the variable-pitch phase mask, tapered and linearly chirped fiber Bragg gratings (TCFBG) with resultant co-directional or counter-directional chirps are achieved. Thus, both effects, those of reduction and enhancement of the grating chirp, as well as their influence on the grating spectral response, are presented. In particular, using the above approach TCFBG with significantly narrowed spectral width are shown. Moreover, fused tapered chirped FBG with relatively large waist diameter are shown having broad spectrum, something that prior to now was not attainable using previously developed techniques.

  4. Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations.

    Science.gov (United States)

    Tan, Quan-Chang; Wu, Jian-Wei; Peng, Fei; Zang, Yuan; Li, Yang; Zhao, Xiong; Lei, Wei; Wu, Zi-Xiang

    2016-06-01

    OBJECTIVE This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw. METHODS Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter. RESULTS The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study results indicated 1.5-ml of PMMA was a conservative volume for PMMA augmentation; more cement injection would significantly increase the risk of cement leakage

  5. A high precision recipe for correcting images distorted by a tapered fiber optic

    International Nuclear Information System (INIS)

    Images captured with a tapered fiber optic camera show significant spatial distortion mainly because the spatial orientation of the fiber bundles is not identical at each end of the taper. We present three different techniques for the automatic distortion correction of images acquired with a charge-coupled device (CCD) camera bonded to a tapered optical fiber. In this paper we report - (i) comparison of various methods for distortion correction (ii) extensive quantitative analysis of the techniques and (iii) experiments carried out using a high resolution fiber optic camera. A pinhole array was used to find control points in the distorted image space. These control points were then associated with their known true coordinates. To apply geometric correction, three different approaches were investigated - global polynomial fitting, local polynomial fitting and triangulated interpolation. Sub-pixel accuracy was achieved in all approaches, but the experimental results reveal that the triangulated interpolation gave the most satisfactory result for the distortion correction. The effect of proper alignment of the mask with the fiber optic taper (FOT) camera was also investigated. It was found that the overall dewarping error is minimal when the mask is almost parallel to the CCD.

  6. Randomized clinical trial comparing blunt tapered and standard needles in closing abdominal fascia.

    NARCIS (Netherlands)

    Nordkam, R.A.; Bluyssen, S.J.; Goor, H. van

    2005-01-01

    Glove perforation frequently occurs during the course of surgical procedures, introducing risks for both surgeons and patients. The aim of this study was to compare the use of blunt tapered and "sharp" needles during abdominal wall closure with respect to the incidence of glove perforation and the c

  7. Optimization of line-tapered MMI devices using a genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Xiao; Jianjiang Zhou; Shujing Li; Lizhen Huang; Dingshan Gao; Huaming Wu

    2009-01-01

    @@ We discuss the optimal design of line-tapered multimode interference (MMI) devices using a genetic al-gorithm (GA).A 1×4 MMI device is designed as a numerical example.Compared with the conventional design based on self-imaging theory, the present method demonstrates superior performance with low in-sertion loss and small non-uniformity.

  8. 77 FR 16859 - Tapered Roller Bearings From China; Scheduling of a Full Five-Year Review

    Science.gov (United States)

    2012-03-22

    ... that a full review pursuant to section 751(c)(5) of the Act should proceed (76 FR 72213, November 22... amended. The amendments took effect on November 7, 2011. See 76 FR 61937 (Oct. 6, 2011) and the newly... COMMISSION Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United...

  9. 77 FR 12326 - Tapered Roller Bearings From China; Scheduling of a Full Five-Year Review

    Science.gov (United States)

    2012-02-29

    ... to section 751(c)(5) of the Act should proceed (76 FR 72213, November 22, 2011). A record of the... amendments took effect on November 7, 2011. See 76 FR 61937 (Oct. 6, 2011) and the newly revised Commission's... COMMISSION Tapered Roller Bearings From China; Scheduling of a Full Five- Year Review AGENCY: United...

  10. Hypnotic Taper with or without Self-Help Treatment of Insomnia: A Randomized Clinical Trial

    Science.gov (United States)

    Belleville, Genevieve; Guay, Catherine; Guay, Bernard; Morin, Charles M.

    2007-01-01

    This study aimed to assess the efficacy of a minimal intervention focusing on hypnotic discontinuation and cognitive-behavioral treatment (CBT) for insomnia. Fifty-three adult chronic users of hypnotics were randomly assigned to an 8-week hypnotic taper program, used alone or combined with a self-help CBT. Weekly hypnotic use decreased in both…

  11. Techniques for chamfer and taper grinding of oxide fuel pellets (LWBR Development Program)

    International Nuclear Information System (INIS)

    Floor mounted centerless grinding machines were adapted for shaping the edges of cylindrical oxide fuel pellets for the Light Water Breeder Reactor (LWBR) by plunge grinding. Edge configurations consisted of chamfers, either 0.015 inch x 450 or 0.006 inch x 450, or tapers 0.150 inch long x .0025 inch deep. Grinding was done by plunging the pellet against a shaped grinding wheel which ground both the diameter to the required size and shaped the edges of the pellet. Two plunges per pellet were required to complete the operation. Separate wheels were needed for grinding either a chamfer or a taper, the set up was adjustable to vary the size of the chamfer or taper as needed. The set up also had the flexibility to accommodate the multiple pellet lengths and diameters required by the LWBR design. Tight manufacturing tolerances in the chamfer and taper dimensions required the use of dimensional control charts and statistical sampling plans as process controls

  12. Effects of Prosthesis Stem Tapers on Stress Distribution of Cemented Hip Arthroplasty

    International Nuclear Information System (INIS)

    Aseptic loosening effects are critical issues in encouraging long term stability of cemented hip arthroplasty. Stress shielding is believed to be an important factor that contributes to the aseptic loosening problems. The numerous changes in the prosthesis stem design are intended to minimize the stress shielding and aseptic loosening problems and to improve the long term performance of the implants. In this study, the stress distribution in cemented hip arthroplasty is established using finite element method. The taper of the prosthesis is designed to be 3 deg. at anterior/posterior, 3 deg. at medial/lateral and 10 deg. from wide lateral to narrow medial. Major muscle loads and contact forces are simulated for walking (toe-off phase) and stair climbing load cases. Effects of prosthesis stem tapers on the resulting stress distribution are investigated. Results show that compressive stress dominates in the medial plane while tensile stress in the lateral plane of the femur. The corresponding stress levels of intact femur for walking and stair-climbing load cases are 22 and 29 MPa, respectively. The magnitude of Tresca stress for the THA femur in stair-climbing load case remains higher in the region of 85 MPa while the walking load case induces around 40 MPa. The stress range in the straight and single taper stem prosthesis is lower than 260 MPa, while localized Tresca stress is in the order of the yield strength of Ti-6Al-4V alloy for double and triple taper stem design.

  13. Fiber Volume Fraction Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

    Science.gov (United States)

    Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

    2015-10-01

    Liquid resin is injected into the tapered injection chamber through the injection slots to completely wetout the fiber reinforcements in a resin injection pultrusion process. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the centerline causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to effectively penetrate through the fibers and achieve complete wetout. Fiber volume fraction in the final pultruded composite is a key to decide the mechanical and/or chemical properties of the composite. If the fiber volume fraction is too high, more fibers are squeezed together creating a fiber lean region near the wall and fiber rich region away from the wall. Also, the design of the injection chamber significantly affects the minimum injection pressure required to completely wet the fibers. A tapered injection chamber is considered such that wetout occurs at lower injection pressures due to the taper angle of the injection chamber. In this study, the effect of fiber volume fraction on the fiber reinforcement compaction and complete fiber wetout for a tapered injection chamber is investigated.

  14. A Tapered Aluminium Microelectrode Array for Improvement of Dielectrophoresis-Based Particle Manipulation

    Directory of Open Access Journals (Sweden)

    Muhamad Ramdzan Buyong

    2015-05-01

    Full Text Available In this work, the dielectrophoretic force (FDEP response of Aluminium Microelectrode Arrays with tapered profile is investigated through experimental measurements and numerical simulations. A standard CMOS processing technique with a step for the formation of a tapered profile resist is implemented in the fabrication of Tapered Aluminium Microelectrode Arrays (TAMA. The FDEP is investigated through analysis of the Clausius-Mossotti factor (CMF and cross-over frequency (fxo. The performance of TAMA with various side wall angles is compared to that of microelectrodes with a straight cut sidewall profile over a wide range of frequencies through FEM numerical simulations. Additionally, electric field measurement (EFM is performed through scanning probe microscopy (SPM in order to obtain the region of force focus in both platforms. Results showed that the tapered profile microelectrodes with angles between 60° and 70° produce the highest electric field gradient on the particles. Also, the region of the strongest electric field in TAMA is located at the bottom and top edge of microelectrode while the strongest electric field in microelectrodes with straight cut profile is found at the top corner of the microelectrode. The latter property of microelectrodes improves the probability of capturing/repelling the particles at the microelectrode’s side wall.

  15. Effect of length and diameter of tapered posts on the retention

    NARCIS (Netherlands)

    Nergiz, [No Value; Schmage, P; Ozcan, M; Platzer, U

    2002-01-01

    The force transmission of tapered unthreaded posts along the root has been reported to be homogenous but their retentive strength was found to be lower compared with those of parallel unthreaded or other kinds of threaded posts. The purpose of this in vitro study was to investigate the effect of len

  16. Bond strengths of five tapered root posts regarding the post surface

    NARCIS (Netherlands)

    Nergiz, [No Value; Schmage, P; Platzer, U; Ozcan, M

    2002-01-01

    The advantage of tapered passive root posts is their homogenous force transmission without creating stress peaks on the root surface because of their anatomical root form. However, their expected retentive strengths are low compared with the other post systems. The objective of this in vitro study w

  17. Near-unity efficiency, single-photon sources based on tapered photonic nanowires

    DEFF Research Database (Denmark)

    Bleuse, Joël; Munsch, Mathieu; Claudon, Julien;

    2012-01-01

    Single-photon emission from excitons in InAs Quantum Dots (QD) embedded in GaAs Tapered Photonic Wires (TPW) already demonstrated a 0.72 collection efficiency, with TPWs were the apex is the sharp end of the cone. Going to alternate designs, still based on the idea of the adiabatic deconfinement ...

  18. Tapering biologic and conventional DMARD therapy in rheumatoid arthritis: current evidence and future directions.

    Science.gov (United States)

    Schett, Georg; Emery, Paul; Tanaka, Yoshiya; Burmester, Gerd; Pisetsky, David S; Naredo, Esperanza; Fautrel, Bruno; van Vollenhoven, Ronald

    2016-08-01

    Improvements in the control of inflammation in rheumatoid arthritis (RA) by conventional synthetic and biologic disease-modifying antirheumatic drugs (DMARDs) have led to a substantial change in the clinical outcomes of patients during the last 30 years. Current treatment can lead to sustained remission in some patients raising questions about the optimal management strategies in this subgroup of patients. Today, tapering of DMARDs and even their discontinuation appears as an interesting concept for achieving a more tailored and dynamic treatment approach of RA, especially in patients, who achieved full disease control by DMARD treatment. In this review article, current developments of DMARD tapering are discussed. The article provides an overview of existing studies on this topic and addresses new strategies to reach drug-free remission. Furthermore, concepts for defining patients eligible for DMARD tapering are described and potential future strategies in using biomarkers in predicting the risk for disease relapse after initiation of DMARD tapering are addressed. These findings are finally considered in light of the vision to achieve cure as an ultimate goal in patients with RA achieving full control of inflammation. PMID:27261493

  19. Novel Fused Taper 1x4 Star Coupler for Full-Band Operation

    Institute of Scientific and Technical Information of China (English)

    Masakazu; Ohashi; Hideki; Sasaki; Ryoukichi; Matsumoto; Daiichiro; Tanaka; Akira; Wada

    2003-01-01

    A novel fused taper 1×4 coupler for full-band operation is proposed. Wavelength flattened characteristics and excellent branching uniformity less than 0.4 dB have been achieved in wavelength range from 1200 nm to 1700 nm.

  20. Survival Rate of Short, Locking Taper Implants with a Plateau Design: A 5-Year Retrospective Study

    OpenAIRE

    Kemal Özgür Demiralp; Nihat Akbulut; Sebnem Kursun; Didem Argun; Nilsun Bagis; Kaan Orhan

    2015-01-01

    Background. Short implants have become popular in the reconstruction of jaws, especially in cases with limited bone height. Shorter implants, those with locking tapers and plateau root shapes, tend to have longer survival times. We retrospectively investigated the cumulative survival rates of Bicon short implants (

  1. Thinning effects on taper of Eremanthus incanus (Less. Less. in natural stands

    Directory of Open Access Journals (Sweden)

    Gabriel William Dias Ferreira

    2014-09-01

    Full Text Available This study aimed to analyze the effect of different thinning intensities on stem taper of Eremanthus incanus in naturally regenerated stands. Data from an experiment located at Morro do Pilar/MG and installed in 2002 were used. About three years after a fire occurrence that provided an intense regeneration of Eremanthus incanus, five thinning intensities were applied and compared with a control treatment with no thinning. Seven and a half years after installation of the trial 360 standing trees in the different thinning treatments and diameter classes were scaled. Three taper equations were tested: Schöepfer (1966, Hradetzky (1976 and Kozak, Munro e Smith (1969, as well as the possibility of grouping the treatments into one equation using the identity test. The equation proposed by Schöepfer (1966 was the most accurate and precise in estimating the diameters along the stem. While the diameters at different stem height were satisfactorily estimated, the three equations tested tended to underestimate the volume of the larger trees. Using the identity test, it was possible to use one taper equation for the two lower thinning intensities, and another to represent the trees placed in the three treatments with higher thinning intensities. Trees grown at lower densities of plants per hectare were found to be more conical compared to the trees at higher densities. Trees of the control treatment were less conical and needed an exclusive taper equation.

  2. Stress distributions in peri-miniscrew areas from cylindrical and tapered miniscrews inserted at different angles

    Science.gov (United States)

    Choi, Sung-Hwan; Kim, Seong-Jin; Lee, Kee-Joon; Sung, Sang-Jin; Chun, Youn-Sic

    2016-01-01

    Objective The purpose of this study was to analyze stress distributions in the roots, periodontal ligaments (PDLs), and bones around cylindrical and tapered miniscrews inserted at different angles using a finite element analysis. Methods We created a three-dimensional (3D) maxilla model of a dentition with extracted first premolars and used 2 types of miniscrews (tapered and cylindrical) with 1.45-mm diameters and 8-mm lengths. The miniscrews were inserted at 30°, 60°, and 90° angles with respect to the bone surface. A simulated horizontal orthodontic force of 2 N was applied to the miniscrew heads. Then, the stress distributions, magnitudes during miniscrew placement, and force applications were analyzed with a 3D finite element analysis. Results Stresses were primarily absorbed by cortical bone. Moreover, very little stress was transmitted to the roots, PDLs, and cancellous bone. During cylindrical miniscrew insertion, the maximum von Mises stress increased as insertion angle decreased. Tapered miniscrews exhibited greater maximum von Mises stress than cylindrical miniscrews. During force application, maximum von Mises stresses increased in both groups as insertion angles decreased. Conclusions For both cylindrical and tapered miniscrew designs, placement as perpendicular to the bone surface as possible is recommended to reduce stress in the surrounding bone. PMID:27478796

  3. High Sensitivity Refractometer Based on TiO₂-Coated Adiabatic Tapered Optical Fiber via ALD Technology.

    Science.gov (United States)

    Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun

    2016-01-01

    Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO₂) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO₂ nanofilm compared to that of silica, an asymmetric Fabry-Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO₂ nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO₂ on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373-1.3500. Due to TiO₂'s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field. PMID:27537885

  4. Fiber Volume Fraction Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

    Science.gov (United States)

    Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

    2016-06-01

    Liquid resin is injected into the tapered injection chamber through the injection slots to completely wetout the fiber reinforcements in a resin injection pultrusion process. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the centerline causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to effectively penetrate through the fibers and achieve complete wetout. Fiber volume fraction in the final pultruded composite is a key to decide the mechanical and/or chemical properties of the composite. If the fiber volume fraction is too high, more fibers are squeezed together creating a fiber lean region near the wall and fiber rich region away from the wall. Also, the design of the injection chamber significantly affects the minimum injection pressure required to completely wet the fibers. A tapered injection chamber is considered such that wetout occurs at lower injection pressures due to the taper angle of the injection chamber. In this study, the effect of fiber volume fraction on the fiber reinforcement compaction and complete fiber wetout for a tapered injection chamber is investigated.

  5. Effects of Tapered Diffuser Vane on the Flow Field and Noise of a Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    Yutaka OHTA; Takashi GOTO; Eisuke OUTA

    2007-01-01

    The effects of a three-dimensional tapered diffuser vane on the flow field and noise radiated from a centrifugal compressor are investigated by both CFD analyses and experiments. Tapered diffuser vanes are very useful not only for the reduction of the interaction tone noise but also for the improvement of the pressure recovery characteristics within the diffuser passage. By using tapered diffuser vanes, the interaction area between the impeller-discharge flow and diffuser vanes becomes small, and then the noise level of the discrete tone can be reduced remarkably as a result. Furthermore, by utilizing the visualization technique of vortical structures based on the CFD results, the scale of vortex shedding leaving from the leading edge of the diffuser vanes is found to be contracted and a tendency for the turbulence level to decrease is observed. This may be the cause of the attenuation of broadband noise components. The secondary flow, which is considered to be an obstruction of diffuser pressure recovery, can also be suppressed by the tapered diffuser vanes, and the pressure decrease observed in the throat part of the diffuser passage is further reducible.

  6. Cutting ability of nickel-titanium rotary systems ProTaper, Mtwo and K3

    Directory of Open Access Journals (Sweden)

    Sergio Herrero Moraes

    2012-06-01

    Full Text Available Introduction: Nickel-titanium rotatory systems should remove dentin during the root canal preparation to promote the enlargement and tapered shape with continuously narrowing towards the apex. Objective: The aim of this study was to analyze the cutting ability of three NiTi rotatory systems (n = 12: ProTaper (group 1, Mtwo (group 2, and K3 (group 3. Material and methods: Thirty six maxillary molar teeth were weighted on an analytical balance before and after the rotatory preparation of the mesio-buccal root canal. Data was statistically analyzed by ANOVA and Tukey’s test with a significance level of 5%. Results: The results revealed the following mass differences (g before and after the root canal preparation: ProTaper (group 1 – 0.0159 ± 0.004, Mtwo (group 2 – 0.0125 ± 0.002, and K3 (group 3 – 0.007 ± 0.003. Conclusion: ProTaper showed the highest cutting ability among the three tested nickeltitanium rotatory systems followed by Mtwo and K3.

  7. Evanescent wave absorption sensor based on tapered multimode fiber coated with monolayer graphene film

    Science.gov (United States)

    Qiu, Hengwei; Gao, Saisai; Chen, Peixi; Li, Zhen; Liu, Xiaoyun; Zhang, Chao; Xu, Yuanyuan; Jiang, Shouzhen; Yang, Cheng; Huo, Yanyan; Yue, Weiwei

    2016-05-01

    An evanescent wave absorption (EWA) sensor based on tapered multimode fiber (TMMF) coated with monolayer graphene film for the detection of double-stranded DNA (DS-DNA) is investigated in this work. The TMMF is a silica multimode fiber (nominally at 62.5 μm), which was tapered to symmetric taper with waist diameters of ~30 μm and total length of ~3 mm. Monolayer graphene film was grown on a copper foil via chemical vapor deposition (CVD) technology and transferred onto skinless tapered fiber core via dry transfer technology. All the components of the sensor are coupled together by fusion splicer in order to eliminate the external disturbance. DS-DNA is created by the assembly of two relatively complemented oligonucleotides. The measurements are obtained by using a spectrometer in the optical wavelength range of 400-900 nm. With the increase of DS-DNA concentration, the output light intensity (OPLI) arisen an obvious attenuation. Importantly, the absorbance (A) and the DS-DNA concentrations shown a reasonable linear variation in a wide range of 5-400 μM. Through a series of comparison, the accuracy of TMMF sensor with graphene (G-TMMF) is much better than that without graphene (TMMF), which can be attributed to the molecular enrichment of graphene by π-π stacking.

  8. Periodically tapered photonic crystal fibre based strain sensor fabricated by a CO2 laser technique

    Science.gov (United States)

    Farrell, Gerald; Bo, Lin; Guan, Chunying; Semenova, Yuliya; Wang, Pengfei

    2014-05-01

    A focused CO2 laser beam has been previously used to successfully fabricate both symmetric and asymmetric long period fiber gratings which have been used for a variety of sensing applications. However fabrication by a CO2 laser beam demands a time consuming laser scanning process which increases the difficulty and cost of fabrication. In this paper a fibre sensor based on a fibre heterostructure with a simple configuration consisting of a series of periodical tapers in a photonic crystal fibre (PCF) sandwiched between two singlemode fibres is proposed and investigated experimentally. The tapers are periodically fabricated along the PCF section using a CO2 laser beam. The proposed fibre heterostructure can be used for strain sensing by measuring the wavelength blueshift of the multimode interference dip of the transmission spectrum as a function of strain. An average stain sensitivity of -68.4 pm/μ ɛ has been experimentally achieved over a microstrain range from 0 to 100 μ ɛ. Assuming in practice that the sensor is interrrogated with a ratiometric power measurement system, then the strain resolution is estimated to be better than 1.18×10-2 microstrain. The mechanisms for refractive index modulation periodically tapered PCF under tensile strain measurements are complex but may be regarded as a combination of stress-relaxation and refractive index perturbations over the length of the tapered PCF induced by strain and by tapering. The proposed fibre strain sensor has the advantage of low temperature sensitivity (average 8.4 pm/°C) and an experimental demonstration of this reduced sensitivity is also presented. The proposed strain sensor benefits from simplicity of fabrication and achieves a competitive sensitivity compared with other existing fibre-optic sensors.

  9. Effect of ripple taper on band-gap overlap in a coaxial Bragg structure operating at terahertz frequency

    Energy Technology Data Exchange (ETDEWEB)

    Ding Xueyong; Li Hongfan; Lv Zhensu [Polytechnic Institute of San Ya University, Sanya, Hainan 572022 (China)

    2012-09-15

    Based on the mode-coupling method, numerical analysis is presented to demonstrate the influence of ripple taper on band-gap overlap in a coaxial Bragg structure operating at terahertz frequency. Results show that the interval between the band-gaps of the competing mode and the desired working mode is narrowed by use of positive-taper ripples, but is expanded if negative-taper ripples are employed, and the influence of the negative-taper ripples is obviously more advantageous than the positive-taper ripples; the band-gap overlap of modes can be efficiently separated by use of negative-taper ripples. The residual side-lobes of the frequency response in a coaxial Bragg structure with ripple taper also can be effectively suppressed by employing the windowing-function technique. These peculiarities provide potential advantage in constructing a coaxial Bragg cavity with high quality factor for single higher-order-mode operation of a high-power free-electron maser in the terahertz frequency range.

  10. THE EFFECT OF TAPERING PERIOD ON PLASMA PRO-INFLAMMATORY CYTOKINE LEVELS AND PERFORMANCE IN ELITE MALE CYCLISTS

    Directory of Open Access Journals (Sweden)

    Peter M. Tiidus

    2009-12-01

    Full Text Available The aim of this study was to investigate the effect of two different tapering period lengths on the concentration of plasma interleukin- 6 (IL-6, interleukin (IL-1β and tumor necrosis factor-? (TNF-α and performance in elite male cyclists. To this end, after completing 8 weeks progressive endurance exercise, twenty four high-level endurance cyclists were randomly assigned to one of two groups: a control group of cyclists (n = 12 continued performing progressive weekly training volume for 3 weeks while a taper group of cyclists (n = 12 proceeded with a 50% reduction in weekly training volume relative to the control group. A simulated 40 min time trial (40TT performance ride was used as the criterion index of performance before and after the tapering period to evaluate the physiological and performance effects of each protocol. Blood samples were collected immediately post-40TT from all participants at the beginning of week 1, and the end of weeks 4, 8, 9 and 11. IL-1β, IL-6 and TNFα were assayed using a standard commercial ELISA kits (Quantikine; R & D Systems, Minneapolis, MN. The mean time to complete the 40TT in the taper group decreased significantly (p < 0.01 after both 1 and 3 weeks with reduced training volume relative to the control group. There were significant reductions in (p < 0.001 IL-1β, IL-6 and TNFα concentrations in the taper group relative to the control group at the end of the 3 week tapering period, but not at the end of the 1 week tapering period. These results demonstrate that both a 1 and a 3 week taper period will result in improved physical performance in trained cyclists but only a 3 week taper period will result in attenuation of post-exercise pro- inflammatory cytokines when compared to those continuing a more intense training regimen

  11. Integration of an optical fiber taper with an optical microresonator fabricated in glass by femtosecond laser 3D micromachining

    CERN Document Server

    Song, Jiangxin; Tang, Jialei; Qiao, Lingling; Cheng, Ya

    2014-01-01

    We report on fabrication of a microtoroid resonator of a high-quality factor (i. e., Q-factor of ~3.24x10^6 measured under the critical coupling condition) using femtosecond laser three-dimensional (3D) micromachining. Coupling of light into and out of the microresonator has been realized with a fiber taper that is reliably assembled with the microtoroid. The assembly of the fiber taper to the microtoroid is achieved by welding the fiber taper onto the sidewall of the microtoroid using CO2 laser irradiation. The integrated microresonator maintains a high Q-factor of 3.21x10^5 as measured in air.

  12. Učinkovitost sustava ProTaper Universal Retreatment™ i ručne tehnike u endodontskoj reviziji

    OpenAIRE

    Aguiar, Carlos Menezes; de Assis Costa Lima, Grasiele; Damo Bernart, Fabiana; Cruz Câmara, Andréa

    2011-01-01

    Svrha istraživanja: Željela se procijeniti učinkovitost sustava ProTaper Universal Retreatment™ i ručnih instrumenata kod endodontske revizije korištenjem dvaju otapala gutaperki – Orange Oila i Eucalypthola. Materijali i metode: Odabrano je 40 meziobukalnih korijena. Podijeljeni su u četiri skupine po 10 uzoraka: I. skupina – punjenje je uklonjeno sustavom ProTaper Universal Retreatment ™ i otapalom Orange Oilom; II. skupina – korijeni su očišćeni sustavom ProTaper Universal Retreatment™ i o...

  13. Complement activation capacity in plasma before and during high-dose prednisolone treatment and tapering in exacerbations of Crohn's disease and ulcerative colitis

    Directory of Open Access Journals (Sweden)

    Baatrup Gunnar

    2005-09-01

    Full Text Available Abstract Background Ulcerative colitis (UC and Crohn's disease (CD are characterized by intestinal inflammation mainly caused by a disturbance in the balance between cytokines and increased complement (C activation. Our aim was to evaluate possible associations between C activation capacity and prednisolone treatment. Methods Plasma from patients with exacerbations of UC (n = 18 or CD (n = 18 were collected before and during high dose prednisolone treatment (1 mg/kg body weight and tapering. Friedman's two way analysis of variance, Mann-Whitney U test and Wilcoxon signed-rank sum test were used Results Before treatment, plasma from CD patients showed significant elevations in all C-mediated analyses compared to the values obtained from 38 healthy controls (p Conclusion Our findings indicate that C activation capacity is up-regulated significantly in plasma from CD patients. The decreases observed after prednisolone treatment reflect a general down-regulation in immune activation.

  14. A Stereomicroscopic Evaluation of Dentinal Cracks at Different Instrumentation Lengths by Using Different Rotary Files (ProTaper Universal, ProTaper Next, and HyFlex CM): An Ex Vivo Study

    Science.gov (United States)

    Shankarappa, Pushpa; Misra, Abhinav; Sawhney, Asheesh; Sridevi, Nandamuri; Singh, Anu

    2016-01-01

    Introduction. The aim of the present study was to evaluate the dentinal cracks after root canal preparation with rotary files: Gates Glidden, ProTaper Universal, ProTaper Next, and HyFlex CM at different instrumentation lengths. Methodology. Sixty-five mandibular premolars were mounted in the acrylic tube with simulated periodontal ligaments and the apex was exposed. The root canals were instrumented with different rotary files, namely, ProTaper Universal, ProTaper Next, and HyFlex CM, to the major apical foramen (AF), short AF, and beyond AF. The root apex was stained with 1% methylene blue dye and digital images of apical surface of every tooth were taken and development of dentinal defects was determined by using stereomicroscope. Multinomial logistic regression test was performed to identify influencing factors. Results. Instrumentation with rotary files terminated 2 mm short AF and did not cause any cracks. Significantly less cracks were seen when instrumentation with rotary files terminated 1 mm short apical foramen when compared with the instrumentation terminated at or beyond apical foramen (p < 0.05). Conclusion. ProTaper Universal rotary files caused more dentinal cracks than ProTaper Next and HyFlex CM. Instrumentation short AF reduced the risk of dentinal defects.

  15. A Stereomicroscopic Evaluation of Dentinal Cracks at Different Instrumentation Lengths by Using Different Rotary Files (ProTaper Universal, ProTaper Next, and HyFlex CM: An Ex Vivo Study

    Directory of Open Access Journals (Sweden)

    Fauzia Ashraf

    2016-01-01

    Full Text Available Introduction. The aim of the present study was to evaluate the dentinal cracks after root canal preparation with rotary files: Gates Glidden, ProTaper Universal, ProTaper Next, and HyFlex CM at different instrumentation lengths. Methodology. Sixty-five mandibular premolars were mounted in the acrylic tube with simulated periodontal ligaments and the apex was exposed. The root canals were instrumented with different rotary files, namely, ProTaper Universal, ProTaper Next, and HyFlex CM, to the major apical foramen (AF, short AF, and beyond AF. The root apex was stained with 1% methylene blue dye and digital images of apical surface of every tooth were taken and development of dentinal defects was determined by using stereomicroscope. Multinomial logistic regression test was performed to identify influencing factors. Results. Instrumentation with rotary files terminated 2 mm short AF and did not cause any cracks. Significantly less cracks were seen when instrumentation with rotary files terminated 1 mm short apical foramen when compared with the instrumentation terminated at or beyond apical foramen (p<0.05. Conclusion. ProTaper Universal rotary files caused more dentinal cracks than ProTaper Next and HyFlex CM. Instrumentation short AF reduced the risk of dentinal defects.

  16. Effect of cyclic torsional preloading on cyclic fatigue resistance of ProTaper Next and Mtwo nickel–titanium instruments

    Directory of Open Access Journals (Sweden)

    Eugenio Pedullà

    2015-06-01

    Conclusions: Torsional preloads reduced the cyclic fatigue resistance of M-wire and conventional (as ProTaper Next and Mtwo NiTi rotary instruments except for Mtwo with 25% or 50% of torsional preloading.

  17. Efficiency Enhancement in a Tapered Free Electron Laser by Varying the Electron Beam Radius

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Yi; Wu, J.; Cai, Y.; Chao, A.W.; Fawley, W.M.; Frisch, J.; Huang, Z.; Nuhn, H.-D.; /SLAC; Pellegrini, C.; /SLAC /UCLA; Reiche, S.; /PSI, Villigen

    2012-02-15

    Energy extraction efficiency of a free electron laser (FEL) can be increased when the undulator is tapered after the FEL saturation. By use of ray equation approximation to combine the one-dimensional FEL theory and optical guiding approach, an explicit physical model is built to provide insight to the mechanism of the electron-radiation coherent interaction with variable undulator parameters as well as electron beam radius. The contribution of variation in electron beam radius and related transverse effects are studied based on the presented model and numerical simulation. Taking a recent studied terawatt, 120 m long tapered FEL as an example, we demonstrate that a reasonably varied, instead of a constant, electron beam radius along the undulator helps to improve the optical guiding and thus the radiation output.

  18. Nonlinear Optics with Tapered Fibers and Magneto-Optically Trapped Rubidium

    Science.gov (United States)

    Little, Bethany; Mullarkey, Chris; Howell, John; Vamivakas, Nick; Lin, Qiang

    2016-05-01

    Tapered optical fibers of sub-wavelength diameter present a promising means of integrating the light-atom interaction into larger scale devices. We present work on a tapered fiber system loaded by a magneto optical trap of Rubidium atoms, in which a combination of red and blue detuned beams create a one-dimensional lattice trap along the fiber. The same fiber is used for interacting with the atoms in the trap via the evanescent fields of light propagating along the fiber. Light storage has been demonstrated in a similar system with Cesium, and we believe that much nonlinear optics remains to be explored in this regime. We also plan to see how these nonlinear effects can be enhanced with the addition of a micro-resonator such as the ones in.

  19. Efficient coupling of light to graphene plasmons by compressing surface polaritons with tapered bulk materials.

    Science.gov (United States)

    Nikitin, A Yu; Alonso-González, P; Hillenbrand, R

    2014-05-14

    Graphene plasmons promise exciting nanophotonic and optoelectronic applications. Owing to their extremely short wavelengths, however, the efficient coupling of photons to propagating graphene plasmons-critical for the development of future devices-can be challenging. Here, we propose and numerically demonstrate coupling between infrared photons and graphene plasmons by the compression of surface polaritons on tapered bulk slabs of both polar and doped semiconductor materials. Propagation of surface phonon polaritons (in SiC) and surface plasmon polaritons (in n-GaAs) along the tapered slabs compresses the polariton wavelengths from several micrometers to around 200 nm, which perfectly matches the wavelengths of graphene plasmons. The proposed coupling device allows for a 25% conversion of the incident energy into graphene plasmons and, therefore, could become an efficient route toward graphene plasmon circuitry. PMID:24773123

  20. Free Vibration and Stability of Axially Functionally Graded Tapered Euler-Bernoulli Beams

    Directory of Open Access Journals (Sweden)

    Ahmad Shahba

    2011-01-01

    Full Text Available Structural analysis of axially functionally graded tapered Euler-Bernoulli beams is studied using finite element method. A beam element is proposed which takes advantage of the shape functions of homogeneous uniform beam elements. The effects of varying cross-sectional dimensions and mechanical properties of the functionally graded material are included in the evaluation of structural matrices. This method could be used for beam elements with any distributions of mass density and modulus of elasticity with arbitrarily varying cross-sectional area. Assuming polynomial distributions of modulus of elasticity and mass density, the competency of the element is examined in stability analysis, free longitudinal vibration and free transverse vibration of double tapered beams with different boundary conditions and the convergence rate of the element is then investigated.

  1. High-resolution optical spectroscopy using multimode interference in a compact tapered fibre

    Science.gov (United States)

    Wan, Noel H.; Meng, Fan; Schröder, Tim; Shiue, Ren-Jye; Chen, Edward H.; Englund, Dirk

    2015-07-01

    Optical spectroscopy is a fundamental tool in numerous areas of science and technology. Much effort has focused on miniaturizing spectrometers, but thus far at the cost of spectral resolution and broad operating range. Here we describe a compact spectrometer that achieves both high spectral resolution and broad bandwidth. The device relies on imaging multimode interference from leaky modes along a multimode tapered optical fibre, resulting in spectrally distinguishable spatial patterns over a wide range of wavelengths from 500 to 1,600 nm. This tapered fibre multimode interference spectrometer achieves a spectral resolution down to 40 pm in the visible spectrum and 10 pm in the near-infrared spectrum (corresponding to resolving powers of 104-105). Multimode interference spectroscopy is suitable in a variety of device geometries, including planar waveguides in a broad range of transparent materials.

  2. Highly tapered pentagonal bipyramidal Au microcrystals with high index faceted corrugation: Synthesis and optical properties

    Science.gov (United States)

    Mettela, Gangaiah; Boya, Radha; Singh, Danveer; Kumar, G. V. Pavan; Kulkarni, G. U.

    2013-05-01

    Focusing light at sub-wavelength region opens up interesting applications in optical sensing and imaging beyond the diffraction limit. In the past, tapered Au wires with carved gratings have been employed to achieve nanofocusing. The fabrication process however, is expensive and the obtained wires are polycrystalline with high surface roughness. A chemical synthetic method overcoming these hurdles should be an attractive alternative. Here, we report a method to chemically synthesize Au microcrystals (~10 μm) bearing pentagonal bipyramidal morphology with surface corrugations assignable to high index planes. The method is a single step solid state synthesis at a temperature amenable to common substrates. The microcrystals are tapered at both ends forming sharp tips (~55 nm). Individual microcrystals have been used as pick and probe SERS substrates for a dye embedded in a polymer matrix. The unique geometry of the microcrystal also enables light propagation across its length.

  3. Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang;

    2010-01-01

    While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from...... air (~11 μm in tissue) in OCT measurements. As our work shows, tapered amplifiers are suitable gain media for swept sources at 1050 nm with increased output power, while high gain counteracts dispersion effects in an FDML laser....... achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion. The light source operates at a repetition rate of 116 kHz with an effective average output power in excess of 30 mW. With a total sweep range of 70 nm, we achieved an axial resolution of 15 μm in...

  4. Method for mounting Gunn Diode in Active Tapered Slot-Ring Antenna

    Directory of Open Access Journals (Sweden)

    Somnath Chatterjee

    2013-03-01

    Full Text Available To find the optimum location of an active device i.e., Gunn diode in the Active tapered Slot-Ring Antenna (ASRA equivalent {ABCD} matrix parameters has been used, so that the best performance in antenna characteristics is realized in terms of power radiated and power received. Microstrip tapered slot-ring antenna was fabricated by using a 0.787mm thick Takonic TLY-5-0310-CH/CH substrate with $varepsilon_r$ = 2.2 and the active device used is commercially available low power MA/COM packaged Gunn diode (MA 49104 with typical dc to rf conversion efficiency of approximately 1.5% for experimental study. Radiation pattern and locking characteristics of the ASRA have been measure and presented in support of the analytical methods.

  5. Simulation study of tapered FEL amplifiers in Raman and Compton regimes

    International Nuclear Information System (INIS)

    The magnetic taper of the wiggler field was studied numerically for an efficiency enhancement of mm wave free electron laser using the 3 dimensional analysis code. The linear taper seems effective to obtain an effective energy conversion. As the total conversion ratio increase as the K parameter increase, the large value of K parameter should be designed for high efficiency FEL. Prior to the simulation, the energy and its spread of the electron beam Esp were measured experimentally at the JAERI mm wave FEL (LAX-1). As a result, Esp = 15 keV at the beam energy of induction linac of 820 keV, which support that the JAERI FEL was operated at the Raman regime. (author)

  6. Total Hip Arthroplasty Using a Polished Tapered Cemented Stem in Hereditary Multiple Exostosis

    Directory of Open Access Journals (Sweden)

    Akio Kanda

    2016-01-01

    Full Text Available A 61-year-old Japanese man underwent right total hip arthroplasty for hereditary multiple exostosis. At first presentation, he had suffered from coxalgia for a long time. On radiographic images, there was a gigantic femoral head, increased shaft angle, and large diameter of the femoral neck. He had also developed coxarthrosis and severe pain of the hip joint. The transformation of the proximal femur bone causes difficulty in setting a cementless total hip prosthesis. Therefore, total hip arthroplasty using a cemented polished tapered stem was performed via a direct lateral approach. Using a cemented polished tapered stem allowed us to deal with the femoral bone transformation and bone substance defectiveness due to exostosis and also minimized the invasiveness of the operation.

  7. Tapering of Polymer Optical Fibers for Compound Parabolic Concentrator Fiber Tip Fabrication

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Fasano, Andrea; Nielsen, Kristian; Aasmul, Søren; Rasmussen, Henrik K.; Bang, Ole

    2015-01-01

    We propose a process for Polymer Optical Fiber (POF) Compound Parabolic Compound (CPC) tip manufacturing using a heat and pull fiber tapering technique. The POF, locally heated above its glass transition temperature, is parabolically tapered down in diameter, after which it is cut to the desired...... output diameter and finally polished to obtain the special CPC tip. The physical mechanism responsible for giving a CPC shape to the POF tip is also investigated. The fabrication process is shown to be sensitive to several manufacturing parameters, such as temperature of the heat source, thermal flux...... from the heat source, and heating time. We further consider the influence of the heating time latter parameter on the geometry of the obtained CPC fiber tips...

  8. Analysis of the polarization rotation effect in the inversely tapered spot size converter.

    Science.gov (United States)

    Jia, Lianxi; Zhou, Haifeng; Liow, Tsung-Yang; Song, Junfeng; Huang, Ying; Tu, Xiaoguang; Luo, Xianshu; Li, Chao; Fang, Qing; Yu, Mingbin; Lo, Guoqiang

    2015-10-19

    Inversely tapered spot size converter (SSC) is widely used to connect silicon waveguide with fiber in silicon photonics. However, the tapered structure may cause polarization rotation and further generate interference fluctuation in the transmission spectrum even of a straight waveguide. We analyzed the light propagation in a straight waveguide with SSC at the both ends with coupling matrix and transmission matrix methods. The analysis results matched with the phenomena we observed in the transmission spectrum. Combining the analysis with the measurement results, we calculated the polarization rotation efficiency of the SSC in different samples and analyzed the origin of the polarization rotation effect. Finally, we discussed the influence of the effect to the DP-QPSK signal and proposed several methods to release the impact. PMID:26480439

  9. Tapered acoustical directional couplers for integrated acousto-optical mode converters with weighted coupling

    Science.gov (United States)

    Herrmann, Harald; Rust, Ulrich; Schafer, Klaus

    1995-03-01

    Weighted coupling for strong sidelobe suppression of integrated acoustooptical mode converters in LiNbO3 using acoustical directional couplers has been studied theoretically and experimentally. A parameter free model for the propagation of surface acoustic waves in guiding structures has been developed based on a step-like variation of the acoustic velocity. Comparisons of theoretical results with experimental ones for acoustic waveguides and directional coupler structures confirm the applicability of the model. A coupled mode description of the acousto-optical polarization conversion in converters with acoustical directional couplers has been developed and applied to several tapered acoustical directional couplers. The model reveals that the conversion characteristics are usually strongly asymmetric. If the directional coupler is appropriately designed, a sidelobe suppression of about 30 dB can be achieved. First experimental results with tapered directional couplers confirm within some limits the theoretical predictions.

  10. Evaluation of the flaring in mandibular molars danger zone using ProTaper rotatory system

    Directory of Open Access Journals (Sweden)

    Fernanda Missao Brugin MATSUBARA

    2005-11-01

    Full Text Available The aim of this study was to evaluate in vitro the flaring in mandibular molars danger zone, after root canal instrumentation with the ProTaper rotatory instrument system. Sixty extracted mandibular molars with fully formed apices had the mesial roots sectioned. The specimens were divided into four groups and instrumented until Shaping X, Shaping 1 and Shaping 2 files, respectively. One group was kept as control with no instrumentation. The results submitted to statistical analysis, showed a 1% significant differenceamong experimental groups, with an enlargement of the flaring in danger zone being directly proportional to the diameter of ProTaper instruments. It is concluded that the use of this instruments on the preparation of mandibular molars is safe because there isn’t any report of root perforation.

  11. Single microdroplet ejection using an ultrasonic longitudinal mode with a PZT/tapered glass capillary.

    Science.gov (United States)

    Lee, Chung-Hoon; Lal, Amit

    2004-11-01

    We have developed an ultrasonic PZT/tapered glass capillary resonant actuator that can eject a single droplet every acoustic cycle without also generating satellite droplets. The mechanism of the actuation is resonant longitudinal motion-induced squeezing of a tapered volume. The actuator is driven at 160 kHz and requires voltages less than 2 Vpp to operate. In this paper, the droplet generation of isopropanol and water mixtures, which have different densities, viscosities, and surface tensions, is investigated. It is determined that the geometrical squeezing mechanism and the ejected jet breakup makes the droplet size independent of frequency, but more a function of the ejecting orifice diameter that is much smaller than the capillary wavelength. PMID:15600097

  12. Experimental measurement and numerical analysis of fused taper shape for optical fiber coupler

    Institute of Scientific and Technical Information of China (English)

    SHUAI Ci-jun; DUAN Ji-an; ZHONG Jue

    2007-01-01

    To find out the effect of the shape of fused taper region on the optical fiber coupler, the fiber couplers were fabricated at different drawing speeds with a six-axes fiber coupler machine. The results, which were obtained from the shape of fused taper region measured with microscope, show that there is a close correlation between the cone angle and optical performance of fiber coupler. High-performance fiber coupler cannot be obtained until rheological shape is controlled accurately. The numerical analysis model, which was built based on generalized Maxwell viscoelastic theory, is resolved with ANSYS software. The calculated results accord with the experimental data. It can apply a theoretic basis for forecasting the shape of fiber coupler fabricated under the conditions of different technological parameters.

  13. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

    2010-01-01

    4.0 nm between the emitters. An output power of 9 W has been achieved at an operating current of 30 A. The combined beam had an M2 value (1/e2) of 5.3 along the slow axis which is comparable to that of a single tapered emitter on the laser bar. The overall beam combining efficiency was measured to......High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality...

  14. Vibration analysis of tapered rotating composite beams using the hierarchical finite element

    Directory of Open Access Journals (Sweden)

    Ghayour R.

    2010-12-01

    Full Text Available A hierarchical finite element model is presented for the flapwise bending vibration analysis of a tapered rotating multi-layered composite beam. The shear and rotary inertia effects are considered based on the higher shear deformation theory to derive the stiffness and mass matrices of a tapered- wisted rotating and composite beam element. Certain non-composite beams for which comparative results are available in the literature are used to illustrate the application of the proposed technique. Dimensionless parameters are identified from the equations of motion and the combined effects of the dimensionless parameters on the modal characteristics of the rotating composite beams are investigated through numerical studies. The results indicate that, comparedwith the conventional finite element method, the hierarchical finite element has the advantage of using fewer elements to obtain a better accuracy in the calculation of the vibration characteristics of rotating beams such as natural frequencies and mode shapes.

  15. Dynamic Response of Tapered Optical Multimode Fiber Coated with Carbon Nanotubes for Ethanol Sensing Application

    Directory of Open Access Journals (Sweden)

    Arafat Shabaneh

    2015-05-01

    Full Text Available Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%, the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s towards ethanol.

  16. Supercontinuum generation in dispersion-tailored lead-silicate fiber taper

    Science.gov (United States)

    Hu, Hongyu; Li, Wenbo; Ma, Shaozhen; Dutta, Niloy K.

    2013-01-01

    In this paper we numerically study the coherence properties of the supercontinuum generated in a lead-silicate microstructured fiber taper, with an increasing core radius along the propagation distance which tailors the dispersion property. Simulations are conducted by adding quantum noise into the input pulse at 1.55 μm, and the complex degree of first-order coherence function and the overall spectral coherence degree are both calculated. Although the spectral broadening is comparable, the coherence degree is shown to vary with different pumping conditions. It decreases with higher peak power and longer duration due to the significant competition between the soliton-fission process and the noise-seeded modulation instability. By controlling the input pulse parameters, it is possible to generate perfectly coherent supercontinuum with a flat broadened spectrum extending to ~5μm in this fiber taper.

  17. Coherence Properties of Supercontinuum Generated in Dispersion-Tailored Lead-Silicate Microstructured Fiber Taper

    Science.gov (United States)

    Hu, Hongyu; Li, Wenbo; Ma, Shaozhen; Dutta, Niloy K.

    2013-05-01

    This article details the numerically studied coherence properties of the supercontinuum generated in a lead-silicate microstructured fiber taper, with an increasing core radius along the propagation distance that tailors the dispersion property. Simulations are conducted by adding quantum noise into the input pulse at 1.55 μm, and the complex degree of first-order coherence function and the overall spectral coherence degree are both calculated. Although the spectral broadening is comparable, the coherence degree is shown to vary with different pumping conditions. It decreases with higher peak power and longer duration due to the significant competition between the soliton-fission process and the noise-seeded modulation instability. By controlling the input pulse parameters, it is possible to generate a perfectly coherent supercontinuum with a flat broadened spectrum extending from ~1 μm to ~5μm in this fiber taper.

  18. Diaphragm-free fiber-optic Fabry-Perot interferometer based on tapered hollow silica tube

    Science.gov (United States)

    Fang, Guocheng; Jia, Pinggang; Liang, Ting; Tan, Qiulin; Hong, Yingping; Liu, Wenyi; Xiong, Jijun

    2016-07-01

    A miniature fiber-optic Fabry-Perot interferometer fabricated by splicing a diaphragm-free hollow silica tube to a single-mode fiber and fusing the inner core to a taper is presented. The tapered zone forces lights to propagate from the fiber core into the silica tube, and the lights is reflected from the end faces of the optical fiber and the hollow silica tube. The contrast ratio of the interference fringe is determined by the minimum inner diameter of hollow silica tube. The responses of the proposed interferometer to high-temperature, gas refractive index, liquid refractive index and pressure were measured and were found to be linear with sensitivities of 16.26 pm/°C, 610.47 nm/RIU, -122.36 dB/RIU and 1.56 pm/kPa, respectively.

  19. Performance evaluation of four-wave mixing in a graphene-covered tapered fiber

    Science.gov (United States)

    Jin, Qiang; Lu, Jiamei; Li, Xibin; Yan, Qiang; Gao, Qianyu; Gao, Shiming

    2016-07-01

    Four-wave mixing in a monolayer graphene-covered tapered fiber is theoretically analyzed by taking into account the influence of the graphene layer on the light-field distribution. A figure-of-merit (FOM) coefficient, considering both the high nonlinearity and the heavy absorption, is redefined to evaluate nonlinear performance. The fiber diameter and length are optimized to acquire a higher FOM. Using such a graphene-covered tapered fiber with an optimal diameter of 0.736 μm, a maximum conversion efficiency of ‑38.07 dB is numerically obtained for the 1.55 μm pump when the graphene length is 34.4 μm and the peak pump power is 10 W. Moreover, a 3 dB bandwidth as broad as 430 nm can be realized in the 1.55 μm telecommunication band.

  20. Wave front adaptation using a deformable mirror for adiabatic nanofocusing along an ultrasharp gold taper

    CERN Document Server

    Schmidt, Slawa; Piglosiewicz, Bjoern; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Gross, Petra

    2013-01-01

    We describe and demonstrate the use of an adaptive wave front optimization scheme for enhancing the efficiency of adiabatic nanofocusing of surface plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic nanofocusing is an emerging and promising scheme for controlled focusing of far field light into nanometric volumes. It comprises three essential steps: SPP excitation by coupling far field light to an SPP waveguide, SPP propagation along the waveguide and adiabatic SPP nanofocusing towards a geometric singularity. For commonly used complex waveguide geometries, such as, e.g., conical metal tapers, a realistic modeling and efficiency optimization is challenging. Here, we use a deformable mirror to adaptively control the wave front of the incident far field light. We demonstrate an eight-fold enhancement in nanofocusing efficiency and analyze the shape of the resulting optimized wave front. The introduced wave front optimization scheme is of general interest for guiding and controlling ...

  1. Tunable modulational instability sidebands via parametric resonance in periodically tapered optical fibers.

    Science.gov (United States)

    Armaroli, Andrea; Biancalana, Fabio

    2012-10-22

    We analyze the modulation instability induced by periodic variations of group velocity dispersion and nonlinearity in optical fibers, which may be interpreted as an analogue of the well-known parametric resonance in mechanics. We derive accurate analytical estimates of resonant detuning, maximum gain and instability margins, significantly improving on previous literature on the subject. We also design a periodically tapered photonic crystal fiber, in order to achieve narrow instability sidebands at a detuning of 35 THz, above the Raman maximum gain peak of fused silica. The wide tunability of the resonant peaks by variations of the tapering period and depth will allow to implement sources of correlated photon pairs which are far-detuned from the input pump wavelength, with important applications in quantum optics. PMID:23187276

  2. Investigation on spectral response of micro-cavity structure by symmetrical tapered fiber tips

    Science.gov (United States)

    Liu, Yan; Li, Yang; Yan, Xiaojun; Li, Weidong

    2016-06-01

    We proposed and experimentally demonstrated a micro-cavity structure made of symmetrical tapered fiber tips. The waist of a conventional fiber taper fabricated from heating and stretching technique is symmetrically cleaved, and the aligned fiber tips with air gap constitute a Fabry-Perot micro-cavity due to the reflection at the tip facet. The spectral responses of such micro-cavity structure have been investigated both in beam propagation models and experiments. The multibeam interference in the micro-cavity and the impact of the waist diameter and cavity length on the spectral response has been successfully demonstrated. And a micro-cavity structure with 45 μm waist diameter was experimentally achieved, the measured spectra agree well with the simulation ones, indicating that the spectral response of the micro-cavity structure is contributed by both the multibeam interference and the Fabry-Perot micro-cavity.

  3. Tapering studies for Terawatt level X-ray FELs with a superconducting undulator

    CERN Document Server

    Emma, Claudio; Emma, Paul; Huang, Zhirong; Pellegrini, Claudio

    2015-01-01

    We study the tapering optimization scheme for a short period, less than two cm, superconducting undulator, and show that it can generate 4 keV X-ray pulses with peak power in excess of 1 terawatt, using LCLS electron beam parameters. We study the e?ect of undulator module length relative to the FEL gain length for continous and step-wise taper pro?les. For the optimal section length of 1.5m we study the evolution of the FEL process for two di?erent superconducting technologies NbTi and Nb3Sn. We discuss the major factors limiting the maximum output power, particle detrapping around the saturation location and time dependent detrapping due to generation and ampli?cation of sideband modes.

  4. Stress analysis on tapered joint surface of keyless propeller by computer simulation; Keyless propeller taper sesshokubu no rikigakuteki kyodo no simulation

    Energy Technology Data Exchange (ETDEWEB)

    Takai, M. [Ministry of Transportation, Tokyo (Japan)

    1998-09-01

    Tapered joint or shrink fit joint have been used in the joint flange and so forth of keyless propeller or power transmission axis. In each case, the power is transmitted by the friction force of surface contact portion and is not only have simple structure as compared to key system but also there are advantages like not having strength reduction due to the stress concentration at the groove notched surface of key and so forth. On the other hand, higher technology is required whether in the case of press fitting of joint surface or the press fitting design of sliding combination and so forth or press fitting process control. As for keyless propeller system, research results regarding the study of the reliability of press fitting portion, reduction of cost by simplifying the press fitting process, reduction of thickness of press fitting portion or reduction of length of joint surface in order to make light shafting and increase the efficiency, effect of friction coefficient on the joint surface and so forth, are reported. In this report, the simulation results using FEM of practical propeller boss from the indentation process to the tapered shaft up to the slip torque process after the indentation are cited. 3 refs., 11 figs., 2 tabs.

  5. Tunable high-power narrow-linewidth semiconductor laser based on an external-cavity tapered amplifier at 670 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Erbert, G.;

    2009-01-01

    A narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. 800 mW output power is obtained, and the laser system is tunable from 655 to 679 nm.......A narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. 800 mW output power is obtained, and the laser system is tunable from 655 to 679 nm....

  6. 1.38 W tunable high-power narrow-linewidth external-cavity tapered amplifier at 670 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Erbert, G.; Sumpf, B.;

    2010-01-01

    A diffraction-limited narrow-linewidth diode laser system based on a tapered amplifier in external cavity is demonstrated. 1.38 W output power is obtained. The laser system is tunable from 659 to 675 nm.......A diffraction-limited narrow-linewidth diode laser system based on a tapered amplifier in external cavity is demonstrated. 1.38 W output power is obtained. The laser system is tunable from 659 to 675 nm....

  7. Shear evaluation of tapered bridge girder panels with steel corrugated webs near the supports of continuous bridges

    OpenAIRE

    Zevallos, E.; Hassanein, M.F.; Real Saladrigas, Esther; Mirambell Arrizabalaga, Enrique

    2016-01-01

    Because of public construction budgets were cut over the last few years, new bridge girders with corrugated webs to reduce the construction costs have become more widely studied and used. In spite that tapered bridge girders with corrugated webs (BGCWs) are used in modern bridges, their shear strength and behaviour rarely exists in literature. Based on available literature, the web of the linearly tapered BGCWs may be divided into three typologies with different structural response to shear f...

  8. A novel temperature-insensitive strain sensor based on tapered fiber grating

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel temperature-insensitive strain sensor based on bandwidth demodulation of the reflected light from the tapered fiber grating is presented, which is simple and low-cost and has considerable potential particularly application for strain sensing,and with the development of the interrogation system, it can demodulate both the bandwidth and the center wavelength of the reflected light from TFG to measure strain and temperature simultaneously.

  9. U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring

    OpenAIRE

    Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

    2016-01-01

    To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes’ Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide–silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed...

  10. Thru-reflect-line calibration for substrate integrated waveguide devices with tapered microstrip transitions

    OpenAIRE

    Díaz Caballero, Elena; BELENGUER MARTÍNEZ, ÁNGEL; Esteban González, Héctor; Boria Esbert, Vicente Enrique

    2013-01-01

    One of the main problems when exciting or measuring substrate integrated waveguide (SIW) devices lies in the need of a good interconnection with planar structures. In this reported work, the negative effects produced by the connectors and the tapered microstrip-to-SIW transitions are de-embedded from the measurements of the SIW structure by a thru-reflect-line calibration with an adequate and cheap SIW calibration kit.

  11. Tapered cladding diameter profile design for high-power tandem-pumped fiber lasers

    Science.gov (United States)

    Huang, Zhihua; Tang, Xuan; Lin, Honghuan; Wang, Jianjun

    2016-05-01

    The thermal effect has become the biggest limiting factor regarding the further power scaling of single mode fiber lasers, and it can lead to coating failure and transverse mode instability. A tapered cladding diameter profile design is proposed for the tandem-pumped fiber laser in this work, as it can smooth the temperature profile and reduce the maximum temperature rise within the fiber tremendously. The improvement in performance of the fiber design is verified by analytical and numerical results.

  12. Optical manipulation of particles and cells using a tapered fibre probe

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Hongbao Xin, Rui Xu & Baojun Li ### Abstract The protocol reported here describes an optical method for flexible manipulation of particles and cells. Using a tapered optical fibre probe launched with a laser at 980-nm wavelength, particles and cells can be stably trapped, targeted driven to designated positions, and flexibly arranged into desired patterns. This method provides a highly potential avenue for highly flexible and precise manipulation of biological objects. ...

  13. Design and Characterization of Tapered Transition and Inductive Window Filter Based on Substrate Integrated Waveguide Technology

    Directory of Open Access Journals (Sweden)

    Nouri Keltouma

    2011-11-01

    Full Text Available Microstrip tapered transition and inductive band-pass filter around 5 GHz, using Substrate Integrated Waveguide technology (SIW are studied in this paper. All the structures are designed with Finite Element Method (FEM and fabricated on a single substrate of Epoxy FR4 using a standard PCB process. The return loss of the proposed filter is better than 20 dB. The measured results for all the structures investigated show a good agreement with the simulation results.

  14. Design and Characterization of Tapered Transition and Inductive Window Filter Based on Substrate Integrated Waveguide Technology

    OpenAIRE

    Nouri Keltouma; Feham Mohammed; Adnan Saghir

    2011-01-01

    Microstrip tapered transition and inductive band-pass filter around 5 GHz, using Substrate Integrated Waveguide technology (SIW) are studied in this paper. All the structures are designed with Finite Element Method (FEM) and fabricated on a single substrate of Epoxy FR4 using a standard PCB process. The return loss of the proposed filter is better than 20 dB. The measured results for all the structures investigated show a good agreement with the simulation results.

  15. Mathematical Modelling of Blood Flow through a Tapered Overlapping Stenosed Artery with Variable Viscosity

    OpenAIRE

    Shit, G. C.; Roy, M.; Sinha, A

    2014-01-01

    This paper presents a theoretical study of blood flow through a tapered and overlapping stenosed artery under the action of an externally applied magnetic field. The fluid (blood) medium is assumed to be porous in nature. The variable viscosity of blood depending on hematocrit (percentage volume of erythrocytes) is taken into account in order to improve resemblance to the real situation. The governing equation for laminar, incompressible and Newtonian fluid subject to the boundary conditions ...

  16. Mathematical modelling of blood flow through a tapered overlapping stenosed artery with variable viscosity

    OpenAIRE

    Shit, G. C.; Roy, M.; Sinha, A

    2012-01-01

    This paper presents a theoretical study of blood flow through a tapered and overlapping stenosed artery under the action of an externally applied magnetic field. The fluid (blood) medium is assumed to be porous in nature. The variable viscosity of blood depending on hematocrit (percentage volume of erythrocytes) is taken into account in order to improve resemblance to the real situation. The governing equation for laminar, incompressible and Newtonian fluid subject to the boundary conditions ...

  17. Optimization of single-step tapering amplitude and energy detuning for high-gain FELs

    Science.gov (United States)

    Li, He-Ting; Jia, Qi-Ka

    2015-01-01

    We put forward a method to optimize the single-step tapering amplitude of undulator strength and initial energy tuning of electron beam to maximize the saturation power of high gain free-electron lasers (FELs), based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimations for parameters corresponding to the linac coherent light source and the Tesla test facility.

  18. Coupling of single NV Center to adiabatically tapered optical single mode fiber

    CERN Document Server

    Vorobyov, Vadim V; Bolshedvorskii, Stepan V; Javadzade, Javid; Lebedev, Nikolay; Smolyaninov, Andrey N; Sorokin, Vadim N; Akimov, Alexey V

    2016-01-01

    We demonstrated a simple and reliable technique of coupling diamond nanocrystal containing NV center to tapered optical fiber. We carefully studied fluorescence of the fiber itself and were able to suppress it to the level lower than single photon emission from the NV center. Single photon statistics was demonstrated at the fiber end as well as up to 3 times improvement in collection efficiency with respect to our confocal microscope

  19. Detecting atoms trapped in an optical lattice using a tapered optical nanofiber

    CERN Document Server

    Hennessy, T

    2014-01-01

    Optical detection of structures with dimensions smaller than an optical wavelength requires devices that work on scales beyond the diffraction limit. Here we present the possibility of using a tapered optical nanofiber as a detector to resolve individual atoms trapped in an optical lattice in the Mott Insulator phase. We show that the small size of the fiber combined with an enhanced photon collection rate can allow for the attainment of large and reliable measurement signals.

  20. WAVE SCATTERING AT A TAPERED FREE END OF AN ELASTIC PLATE

    OpenAIRE

    Yagoub Nassar Al-Nassar

    2011-01-01

    This paper focuses on the interaction of SH elastic waves in a plate with a tapered free end. The plate is modeled as a semi-infinite elastic structure, which was assumed to have traction-free surfaces. The results of the analysis based on mode matching are presented for various combinations of normalized frequencies and angles of free end inclination. The reported observations form important guidelines for the interpretation of experimental data when using horizontally polarized wave as ...

  1. Evaluation of the flaring in mandibular molars danger zone using ProTaper rotatory system

    OpenAIRE

    Fernanda Missao Brugin MATSUBARA; Janaina Glaucia Trevizan PEREIRA; Flares BARATTO FILHO; Gisele Aihara HARAGUSHIKU; Flávia Sens FAGUNDES

    2005-01-01

    The aim of this study was to evaluate in vitro the flaring in mandibular molars danger zone, after root canal instrumentation with the ProTaper rotatory instrument system. Sixty extracted mandibular molars with fully formed apices had the mesial roots sectioned. The specimens were divided into four groups and instrumented until Shaping X, Shaping 1 and Shaping 2 files, respectively. One group was kept as control with no instrumentation. The results submitted to statistical analysis, showed ...

  2. Reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of canal preparation

    Directory of Open Access Journals (Sweden)

    Amir Abbas Moshari

    2015-01-01

    Full Text Available Aims: The aim of this study was to evaluate the reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of the canal preparation. Materials and Methods: Mandibular first molars (n = 103 with curved mesiobuccal canals were divided into one control (n = 5 and 7 experimental (n = 14 groups, were inoculated with E. faecalis (ATTC 29212 and prepared with the following RaCe files (FKG Dentaire as master apical file: Groups: 25.04, 25.06, 30.04, 30.06, 35.04, 35.06 and 40.06. All the experimental groups were irrigated with 2 mL of 1% sodium hypochlorite during instrumentation and finally rinsed with 17% ethylenediaminetetraacetic acid (EDTA (2 mL followed by 5.25% NaOCl (2 mL and sterile distilled water. Colony counting was performed after incubation. Statistical Analysis Used: Resulting data were analyzed using one-way ANOVA and Tukey′s post-hoc test, (P < 0.05. Results and Conclusions: All the experimental groups showed significant bacterial reduction (P < 0.001. Although the greater the size/taper or both led to more decreased amount of bacteria, differences between the groups with the identical size and different tapers, and among the groups with the same taper and different sizes were not significant. Based on this study, 25.04 along with using 2 mL of 1% NaOCl during instrumentation, and using 17% EDTA and 5.25% NaOCl as final rinse successively after the termination of preparation, can effectively reduce intra-canal bacteria and preserve root structure.

  3. High energy supercontinuum sources using tapered photonic crystal fibers for multispectral photoacoustic microscopy

    Science.gov (United States)

    Bondu, Magalie; Brooks, Christopher; Jakobsen, Christian; Oakes, Keith; Moselund, Peter Morten; Leick, Lasse; Bang, Ole; Podoleanu, Adrian

    2016-06-01

    We demonstrate a record bandwidth high energy supercontinuum source suitable for multispectral photoacoustic microscopy. The source has more than 150 nJ/10 nm bandwidth over a spectral range of 500 to 1600 nm. This performance is achieved using a carefully designed fiber taper with large-core input for improved power handling and small-core output that provides the desired spectral range of the supercontinuum source.

  4. Two-Element Tapered Slot Antenna Array for Terahertz Resonant Tunneling Diode Oscillators

    OpenAIRE

    Jianxiong Li; Yunxiang Li; Weiguang Shi; Haolin Jiang; Luhong Mao

    2014-01-01

    Two-element tapered slot antenna (TSA) array for terahertz (THz) resonant tunneling diode (RTD) oscillators is proposed in this paper. The proposed TSA array has the advantages of both the high directivity and high gain at the horizontal direction and hence can facilitate the horizontal communication between the RTD oscillators and other integrated circuit chips. A MIM (metal-insulator-metal) stub with a T-shaped slot is used to reduce the mutual coupling between the TSA elements. The validit...

  5. High energy supercontinuum sources using tapered photonic crystal fibers for multispectral photoacoustic microscopy.

    Science.gov (United States)

    Bondu, Magalie; Brooks, Christopher; Jakobsen, Christian; Oakes, Keith; Moselund, Peter Morten; Leick, Lasse; Bang, Ole; Podoleanu, Adrian

    2016-06-01

    We demonstrate a record bandwidth high energy supercontinuum source suitable for multispectral photoacoustic microscopy. The source has more than 150  nJ/10  nm bandwidth over a spectral range of 500 to 1600 nm. This performance is achieved using a carefully designed fiber taper with large-core input for improved power handling and small-core output that provides the desired spectral range of the supercontinuum source. PMID:26836298

  6. Performance of nonsynchronous noncommensurate impedance transformers in comparison to tapered line transformers

    DEFF Research Database (Denmark)

    Kim, Kseniya; Zhurbenko, Vitaliy; Johansen, Tom Keinicke;

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of high- and low-impedance transmission lines. The present work is dedicated to the synthesis of such transformers. They are analyzed employing wave transmission matrices. The performance of the transformer is compared...... to a traditional tapered line impedance transformer. The increase in bandwidth of nonsynchronous noncommensurate impedance transformers typically leads to shortening the transformer length, which makes the transformer attractive for applications, where a wide operating band and high transformation...

  7. Bone Remodeling Around Implants with External Hexagon and Morse-Taper Connections

    DEFF Research Database (Denmark)

    Pessoa, Roberto S; Sousa, Ravel M; Pereira, Leandro M;

    2016-01-01

    OBJECTIVES: To evaluate clinical, radiographic, microbiologic, and biomechanical parameters related to bone remodeling around implants with external hexagon (EH) and Morse-taper (MT) connections. MATERIALS AND METHODS: Twelve totally edentulous patients received four custom-made implants in the...... interforaminal region of the mandible. Two of those implants had the same macroscopic design, but different prosthetic connections. All patients received an immediate implant-supported prosthesis. Clinical parameters (periimplant probing pocket depth (PPD), modified gingival index (mGI), and mucosal thickness...

  8. Modelling of Burning Surface Regression of Taper Convex Star Propellant Grain

    OpenAIRE

    Himanshu Shekhar

    2000-01-01

    The burn area calc,ulhtion of al propellant, grain with taper convex star Port is discussed and a software developed, usIng a new zoning definition of the star cross-section,is elaborated. The evolution of lengthwise conditions,inclusion of a coupled sustainer mode, real-time calculations andcalculation for sliver burrling part make this software a versatile tool for propellant grain design and parametric studies.

  9. Assessing the material loss of the modular taper interface in retrieved metal-on-metal hip replacements

    Science.gov (United States)

    Bills, Paul J.; Racasan, R.; Tessier, P.; Blunt, L. A.

    2015-06-01

    Measuring the amount of material loss in the case of revised hip replacements is considered to be a prerequisite of understanding and assessing the true in vivo performance of the implant. This paper outlines a method developed by the authors for quantifying taper material loss as well as more general taper interface parameters. Previous studies have mostly relied on visual inspection to assess the material loss at the taper interface, whereas this method aims to characterize any surface and form changes through the use of an out-of-roundness measurement machine. Along with assessing the volumetric wear, maximum linear penetration and taper contact length can also be determined. The method was applied to retrieved large head metal-on-metal femoral heads in order to quantify the material loss at this junction. Material loss from the female femoral head taper can be characterized as a localized area that is in contact with the stem taper surface. The study showed that this method has good repeatability and a low level of interoperability variation between operators.

  10. Evaluation of surgical impaction technique and how it affects locking strength of the head-stem taper junction.

    Science.gov (United States)

    Scholl, Laura; Schmidig, Gregg; Faizan, Ahmad; TenHuisen, Kevor; Nevelos, Jim

    2016-07-01

    Cases of fretting and corrosion at the taper junction have been reported in large metal-on-metal bearing combinations, and more recently, this concern has included metal-on-polyethylene bearing combinations. Many of these patients have been revised due to adverse local tissue reaction secondary to taper corrosion. This taper corrosion-related adverse local tissue reaction seems to be a multifactorial issue and difficult to assess. The aim of this study was to look at one potential variable, the impaction behavior (impaction force, number of blows, etc.) of orthopedic surgeons, and understand how this can affect the locking strength of tapers. A group of experienced orthopedic surgeons were asked to use their typical surgical approach to impact a femoral head onto a hip femoral stem using an Operating Room (OR)-simulated test setup. Impaction parameters such as impaction force, velocity, and energy, as well as the number of impacts, were characterized and applied in a bench-top study used to evaluate the effect of these parameters on the initial stability of the taper junction. High variation was found in the surgical impaction parameters, but overall it was determined that increased impaction force correlated to superior stability of the taper junction. PMID:27107031

  11. John H. Dillon Medal: Tapered Block Copolymers: Tuning Self-Assembly and Properties by Manipulating Monomer Segment Distributions

    Science.gov (United States)

    Epps, Thomas

    The self-assembly of block copolymers (BCPs) presents unique opportunities to design materials with attractive chemical and mechanical properties based on the ability of BCPs to form periodic structures with nanoscale domain spacings. One area of recent progress in our group focuses on the behavior of tapered BCPs in which the segment distribution at the interface between blocks is synthetically varied to tune morphology, domain density profiles, thermal transitions as well as mechanical and transport properties. Two application targets for these materials are lithium-ion conducting membranes for batteries and nanostructured thin films for nanotemplates and barrier membranes. In the first target area, we found that the taper volume fraction and composition allow us to manipulate the self-assembly of salt-doped BCPs in a well-defined manner that permits optimization of morphology and ion-content. Additionally, we found that the tapered interfaces influence the glass-transition behavior of the ion-conducting block leading to significant changes in lithium-ion transport (ion conductivity). In the second target area, we found the taper content alters the rate of self-assembly as well as the rate of island/hole formation (and ultimate island/hole size) upon thermal annealing. Additionally, using reflectivity techniques, we probed the domain density profiles as a function of taper composition and linked these profiles to changes in domain spacing and glass transition temperature. Overall, these studies show the versatility of tapering to provide a unique handle for simultaneously optimizing multiple materials properties.

  12. Influence of pitch, twist, and taper on a blade`s performance loss due to roughness

    Energy Technology Data Exchange (ETDEWEB)

    Tangler, J.L. [National Renewable Energy Laboratory, Golden, Colorado (United States)

    1997-08-01

    The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. (au)

  13. Mode Transition of RNA Trap by Electric and Hydraulic Force Field in Microfluidic Taper Shape Channel

    Science.gov (United States)

    Takamura, Yuzuru; Ueno, Kunimitsu; Nagasaka, Wako; Tomizawa, Yuichi; Tamiya, Eiichi

    2007-03-01

    We have discovered a phenomenon of accumulation of DNA near the constricted position of a microfluidic chip with taper shaped channel when both hydro pressure and electric field are applied in opposite directions. However, RNA has not been able to trap so far, unlike huge and uniformly double stranded DNA molecules, RNAs are smaller in size and single stranded with complicated conformation like blocks in lysed cell solution. In this paper, we will report not only large but also small RNA (100˜10b) are successfully trapped in relatively large microfluidic taper shape channel (width >10um). RNA are trapped in circular motion near the constricted position of taper shape channel, and the position and shape of the trapped RNA are controlled and make mode transition by changing the hydraulic and the electric force. Using this technique, smaller size molecule can be trapped in larger micro fluidic structure compared to the trap using dielectrophoresis. This technique is expected to establish easy and practical device as a direct total RNA extraction tool from living cells or tissues.

  14. Minimum weight design of rectangular and tapered helicopter rotor blades with frequency constraints

    Science.gov (United States)

    Chattopadhyay, Aditi; Walsh, Joanne L.

    1988-01-01

    The minimum weight design of a helicopter rotor blade subject to constraints on coupled flap-lag natural frequencies has been studied. A constraint has also been imposed on the minimum value of the autorotational inertia of the blade in order to ensure that it has sufficient inertia to autorotate in the case of engine failure. The program CAMRAD is used for the blade modal analysis and CONMIN is used for the optimization. In addition, a linear approximation analysis involving Taylor series expansion has been used to reduce the analysis effort. The procedure contains a sensitivity analysis which consists of analytical derivatives of the objective function and the autorotational inertia constraint and central finite difference derivatives of the frequency constraints. Optimum designs have been obtained for both rectangular and tapered blades. Design variables include taper ratio, segment weights, and box beam dimensions. It is shown that even when starting with an acceptable baseline design, a significant amount of weight reduction is possible while satisfying all the constraints for both rectangular and tapered blades.

  15. A broadband gyrotron backward-wave oscillator with tapered interaction structure and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Li, G. D.; Chang, P. C.; Chiang, W. Y.; Lin, P. N.; Kao, S. H.; Lin, Y. N.; Huang, Y. J.; Barnett, L. R.; Chu, K. R., E-mail: krchu@yahoo.com.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Chen, H. Y.; Fan, C. T. [Wave Power Technology, 232 Youyi Road, Zhunan, Miaoli, Taiwan (China)

    2015-11-15

    The gyro-monotron and gyrotron backward-wave oscillator (gyro-BWO) are the two oscillator versions of gyrotrons. While serving different functions, they are also radically different in the RF field formation mechanisms. The gyro-monotron RF field profile is essentially fixed by the resonant interaction structure, while the gyro-BWO possesses an extra degree of freedom in that the axial RF field profile is self-determined by the beam-wave interaction in a waveguide structure. The present study examines ways to utilize the latter feature for bandwidth broadening with a tapered magnetic field, while also employing a tapered waveguide to enhance the interaction efficiency. We begin with a mode competition analysis, which suggests the theoretical feasibility of broadband frequency tuning in single-mode operation. It is then shown in theory that, by controlling the RF field profile with an up- or down-tapered magnetic field, the gyro-BWO is capable of efficient operation with a much improved tunable bandwidth.

  16. Magnetically assisted gas-solid fluidization in a tapered vessel: Part Ⅱ Dimensionless bed expansion scaling

    Institute of Scientific and Technical Information of China (English)

    Jordan Hristov

    2009-01-01

    The article presents an effort to create dimensionless scaling correlations of the overall bed porosity in the case of magnetically assisted fluidization in a tapered vessel with external transverse magnetic field. This is a stand of portion of new branch in the magnetically assisted fluidization recently created con-cerning employment of tapered vessels. Dimensional analysis based on "pressure transform" of the initial set of variables and involving the magnetic granular Bond number has been applied to develop scaling relationships of dimensionless groups representing ratios of pressures created by the fluid flow, gravity and the magnetic field over an elementary volume of the fluidized bed. Special attention has been paid on the existing data correlations developed for non-magnetic beds and the links to the new ones especially developed for tapered magnetic counterparts. A special dimensionless variable Xp = (Ar△DbL)1/3(√RgMQ) combining Archimedes and Rosensweig numbers has been conceived for porosity correlation. Data cor-relations have been performed by power-law, exponential decay and asymptotic functions with analysis of their adequacies and accuracies of approximation.

  17. Evanescent wave optical trapping and transport of micro- and nanoparticles on tapered optical fibers

    International Nuclear Information System (INIS)

    We investigate the manipulation of microscopic and nanoscopic particles using the evanescent optical field surrounding an optical fiber that is tapered to a micron-scale diameter, and propose that this scheme could be used to discriminate between, and thereby sort, metallic nanoparticles. First we show experimentally the concept of the transport of micron-sized spheres along a tapered fiber and measure the particle velocity. Having demonstrated the principle we then consider theoretically the application to the optical trapping and guiding of metallic nanoparticles, where the presence of a plasmon resonance is used to enhance optical forces. We show that the dynamics of the nanoparticles trapped by the evanescent field can be controlled by the state of polarization of the fiber mode, and by using more than one wavelength differently detuned from the nanoparticle plasmon resonance. Such a scheme could potentially be used for selectively trapping and transporting nano- or microscopic material from a polydisperse suspension. -- Highlights: ► We fabricate single-mode tapered optical fibers of sub-micron diameter. ► We demonstrate trapping of microparticles in the evanescent field of the . ► We demonstrate transport of microparticles along the fiber propelled by radiation pressure. ►We calculate the optical trapping and propelling forces on nanoparticles. ► We show these forces are enhanced by using a laser tuned close to a nanoparticle plasmon resonance.

  18. Influence of pitch, twist, and taper on a blade`s performance loss due to roughness

    Energy Technology Data Exchange (ETDEWEB)

    Tangler, J.L. [National Renewable Energy Lab., Golden, CO (United States)

    1996-12-31

    The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. 8 refs., 6 figs.

  19. Taper functions and merchantable timber for temperate forests of northern Mexico

    Directory of Open Access Journals (Sweden)

    José Návar

    2013-05-01

    Full Text Available Taper functions are required in modern forest management in estimationof the end forest products, to be classified for their life time in the environment. Based on a sample of 1640 trees of 10 species measured in volume, biomass and taper project on Mexico’s northern temperate, mixed, uneven-aged coniferous forests, 12 stem profile taper functions were fitted in order to select the equation that provides better diameter estimates at commercial tree height. Although several equations fitted better specific tree species, the Newnham (1990 equation consistently yielded better diameter estimates at any length of the stem for all studied species. The confidence intervals on the Newnham (1990 equation parameters showed that each species has an unique stem profile and, therefore, single parameter equations are reported. Because of lack of analytical integration, the recommendedtaper equation (when numerically integrated provided compatible,unbiased total bole volume when contrasted to conventional timber volume assessments. Data for 637 circular, 1/10 ha, plots from temperate forests of Central Durango, Mexico estimated a mean of 135 m3 ha-1, of which 18, 59, 30, and 17 m3 ha-1 could be classified as poles, sawn wood, plywood and secondary forest products, respectively. This information can be used for the planning of the forest industry to optimize forest products derived from timber harvesting, as well as for estimating other environmental components.

  20. Tapered Optical Fiber Humidity Sensor Coated with Nano-crystalline ZnO Doped with KCI

    Directory of Open Access Journals (Sweden)

    Sivacoumar Rajalingam

    2015-03-01

    Full Text Available In this research study we have targeted to fabricate a tapered optical fiber coated with zinc oxide doped with KCl to improve the humidity sensing capability of zinc oxide. The optical fiber was tapered through chemical etching method by HF acid (49.5%. The nano-crystalline Zinc Oxide (ZnO was synthesized using single molecular precursor method doped with KCl. The resulting material was characterized with Fourier Transform Infrared spectroscopy (FTIR, X-Ray Diffractometry (XRD and Scanning Electron Microscopy (SEM. The sensing mechanism of this sensor is based on the change of the optical properties of the coating when the relative humidity increases. The humidity sensing characteristic has been estimated by measuring the Optical Permeability (OP as a function of percentage of Relative Humidity (%RH in the ranging from 5 to 98% inside a closed chamber. The tapered optical fiber tested with an overlay coating at the optimal working point achieves better sensitivity. The experimental results show that the 5.7 wt% KCl doped ZnO nano-fibers hold super-rapid response and recovery than normal ZnO coating.

  1. Modeling of stem taper models for Chamaecyparis obtusa in Jeju Island, Korea

    Science.gov (United States)

    SungCheol, Jung; YeonOk, Seo; Roscinto ian, Lumbres; SeongYoun, Lee; ChanSoo, Kim

    2016-04-01

    This study was conducted to fit the different commonly used stem taper models in predicting the diameter over bark at any given height (d) and total volume of Chamaecyparis obtusa in Jeju Island, Korea. The performance of the stem taper models were evaluated using four fit statistics and these were standard error of estimate (SEE), mean bias ( PIC ), absolute mean difference (AMD), and coefficient of determination (R2). Lack-of-fit statistics were also determine and in this study, SEE, AMD and PIC of the different models in predicting d in the different relative height classes and in predicting the total volume in the different diameter at breast height (DBH) classes were calculated. Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics with SEE of 1.3327, PIC of 0.0020 cm, AMD of 0.9970 cm and R2of 0.9958. Based on the lack of fit statistics, this model also showed a good performance in predicting d in most of the relative height classes and in estimating the total volume in the different DBH classes. The result of this study could help forest managers to determine the d, merchantable stem volumes and total stem volumes of Chamaecyparis obtusa in Jeju Island, Korea.

  2. Design of a Tapered and Twisted Blade for the NREL Combined Experiment Rotor; TOPICAL

    International Nuclear Information System (INIS)

    A tapered/twisted blade was designed to operate on the Combined Experiment Rotor (CER) of the National Renewable Energy Lab., which is a stall-regulated downwind wind turbine having a rated power of 20 kilowatt. The geometry of the new blade set was optimized based on annual energy production subject to the constraints imposed on the design. These constraints were mainly related to scientific needs for fundamental research in rotor aerodynamics. A trade-off study was conducted to determine the effect of the different design constraints. Based on the results of this study, which considered nonlinear twist and taper distributions as well as the NREL S809, S814, S822 and S823 airfoils, a blade having a linear taper and a nonlinear twist distribution that uses the S809 airfoil from root to tip was selected. This blade configuration is the logical continuation of the previous constant-chord twisted and untwisted blade sets and will facilitate comparison with those earlier blades. Despite th e design constraints based on scientific needs, the new blade is more representative of commercial blades than the previous blade sets

  3. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    Directory of Open Access Journals (Sweden)

    Milad Farzadi

    2013-02-01

    Full Text Available Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS, which is a Tapered Interference Fit (TIF with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tightening and loosening torques, contactpressure and preloads with and without bone tissue in this analysis. The efficiency is defined as the ratio of the loosening torque to the tightening torque. The effects of the change in elastic modulus and thickness of the bone on operation of this mechanism were investigated.Results: In this study, 14 independent parameters such as taper angle, friction coefficient, abutment and implantgeometry that are effective on performance of TIS mechanism were presented. The role of some factors was shown in the performance of ITI implant using sensitivity analysis.Conclusion: It was shown that friction coefficient, contact length, and implant radius play major roles on tightening and loosening torques and efficiency of the mechanism. Furthermore, the results revealed that the change in the elastic modulus and thickness of the bone influenced the efficiency of the mechanism less than 15%.

  4. Segmentation of the Manila subduction system from migrated multichannel seismics and wedge taper analysis

    Science.gov (United States)

    Zhu, Junjiang; Sun, Zongxun; Kopp, Heidrun; Qiu, Xuelin; Xu, Huilong; Li, Sanzhong; Zhan, Wenhuan

    2013-12-01

    Based on bathymetric data and multichannel seismic data, the Manila subduction system is divided into three segments, the North Luzon segment, the seamount chain segment and the West Luzon segment starts in Southwest Taiwan and runs as far as Mindoro. The volume variations of the accretionary prism, the forearc slope angle, taper angle variations support the segmentation of the Manila subduction system. The accretionary prism is composed of the outer wedge and the inner wedge separated by the slope break. The backstop structure and a 0.5-1 km thick subduction channel are interpreted in the seismic Line 973 located in the northeastern South China Sea. The clear décollement horizon reveals the oceanic sediment has been subducted beneath the accretionary prism. A number of splay faults occur in the active outer wedge. Taper angles vary from 8.0° ± 1° in the North Luzon segment, 9.9° ± 1° in the seamount segment to 11° ± 1° in the West Luzon segment. Based on variations between the taper angle and orthogonal convergence rates in the world continental margins and comparison between our results and the global compilation, different segments of the Manila subduction system fit well the global pattern. It suggests that subduction accretion dominates the north Luzon and seamount chain segment, but the steep slope indicates in the West Luzon segment and implies that tectonic erosion could dominate the West Luzon segment.

  5. Efficient generation of 509 nm light by sum-frequency mixing between two tapered diode lasers

    DEFF Research Database (Denmark)

    Tawfieq, Mahmoud; Jensen, Ole Bjarlin; Hansen, Anders Kragh;

    2015-01-01

    We demonstrate a concept for visible laser sources based on sum-frequency generation of beam com- bined tapered diode lasers. In this specific case, a 1.7 W sum-frequency generated green laser at 509 nm is obtained, by frequency adding of 6.17 W from a 978 nm tapered diode laser with 8.06 W from a...... 1063 nm tapered diode laser, inside a periodically poled MgO doped lithium niobate crystal. This corresponds to an optical to optical conversion ef fi ciency of 12.1%. As an example of potential applica- tions, the generated nearly diffraction-limited green light is used for pumping a Ti:sapphire laser......, thus demonstrating good beam quality and power stability. The maximum output powers achieved when pumping the Ti:sapphire laser are 226 mW (CW) and 185 mW (mode-locked) at 1.7 W green pump power. The optical spectrum emitted by the mode-locked Ti:sapphire laser shows a spectral width of about 54 nm...

  6. Efficiency enhancement of a two-beam free-electron laser using a nonlinearly tapered wiggler

    Institute of Scientific and Technical Information of China (English)

    Maryam Zahedian; B.Maraghechi; M.H.Rouhani

    2012-01-01

    A nonlinear and non-averaged model of a two-beam free-electron laser (FEL) wiggler that is tapered nonlinearly in the absence of slippage is presented.The two beams are assumed to have different energies,and the fundamental resonance of the higher energy beam is at the third harmonic of the lower energy beam.By using Maxwell's equations and the full Lorentz force equation of motion for the electron beams,coupled differential equations are derived and solved numerically by the fourth-order Runge-Kutta method.The amplitude of the wiggler field is assumed to decrease nonlinearly when the saturation of the third harmonic occurs.By simulation,the optimum starting point of the tapering and the slopes for reducing the wiggler amplitude are found.This technique can be applied to substantially improve the efficiency of the two-beam FEL in the XUV and X-ray regions.The effect of tapering on the dynamical stability of the fast electron beam is also studied.

  7. Body Odor

    Science.gov (United States)

    ... Health Medical Conditions Nutrition & Fitness Emotional Health Body Odor Posted under Health Guides . Updated 29 October 2014. + ... guy has to deal with. What causes body odor? During puberty, your sweat glands become much more ...

  8. Body Hygiene

    Science.gov (United States)

    ... Home Diaper-Changing Steps for Childcare Settings Body Hygiene Dental Hygiene Water Fluoridation Facial Cleanliness Fish Pedicures and ... spread of hygiene-related diseases . Topics for Body Hygiene Facial Cleanliness Dental Hygiene Water Fluoridation Fish Pedicures and Fish Spas ...

  9. Body Image

    Science.gov (United States)

    ... Help your child have a healthy body image Cosmetic surgery Breast surgery Botox Liposuction Varicose or spider veins Body dysmorphic disorder (BDD) Eating disorders Anorexia nervosa Binge eating ... nervosa Cosmetics and your health Depression during and after pregnancy ...

  10. Body Basics

    Science.gov (United States)

    ... about how the body works, what basic human anatomy is, and what happens when parts of the body don't function properly. Blood Bones, Muscles, and Joints Brain and Nervous System Digestive System Endocrine System Eyes Female Reproductive System ...

  11. Body embellishment

    OpenAIRE

    Zellweger, Christoph

    2015-01-01

    The exhibition Body Embellishment explores the most innovative artistic expression in the 21st-century international arenas of body extension, augmentation, and modification, focusing on jewelry, tattoos, nail arts, and fashion. The areas of focus are jewelry, tattoos, nail arts, and fashion. Avant-garde jewelry consciously engages the body by intersecting and expanding the planes of the human form. Tattoos are at once on and in the body. Nail art, from manicures to pedicures, has humble ...

  12. Body Clock

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2000-01-01

    Body clocks” are biological methods of controling body activities.Every living thing has one. In humans, a body clock controls normal periods of sleeping and waking. It controls the time swhen you are most likely to feel pain.Eating, sleeping and exercising at about the same time each day will help keep body activities normal. But changes in your life, a new job, for example, destroy the balance and thus cause health problems.

  13. Theoretical calculations and experimental verification for the pumping effect caused by the dynamic micro-tapered angle

    Science.gov (United States)

    Cai, Yufei; Zhang, Jianhui; Zhu, Chunling; Huang, Jun; Jiang, Feng

    2016-05-01

    The atomizer with micro cone apertures has advantages of ultra-fine atomized droplets, low power consumption and low temperature rise. The current research of this kind of atomizer mainly focuses on the performance and its application while there is less research of the principle of the atomization. Under the analysis of the dispenser and its micro-tapered aperture's deformation, the volume changes during the deformation and vibration of the micro-tapered aperture on the dispenser are calculated by coordinate transformation. Based on the characters of the flow resistance in a cone aperture, it is found that the dynamic cone angle results from periodical changes of the volume of the micro-tapered aperture of the atomizer and this change drives one-way flows. Besides, an experimental atomization platform is established to measure the atomization rates with different resonance frequencies of the cone aperture atomizer. The atomization performances of cone aperture and straight aperture atomizers are also measured. The experimental results show the existence of the pumping effect of the dynamic tapered angle. This effect is usually observed in industries that require low dispersion and micro- and nanoscale grain sizes, such as during production of high-pressure nozzles and inhalation therapy. Strategies to minimize the pumping effect of the dynamic cone angle or improve future designs are important concerns. This research proposes that dynamic micro-tapered angle is an important cause of atomization of the atomizer with micro cone apertures.

  14. Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe

    Science.gov (United States)

    Fujii, T.; Taguchi, Y.; Saiki, T.; Nagasaka, Y.

    2012-12-01

    A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

  15. Comparison of stem taper equations for eight major tree species in the Spanish Plateau

    Directory of Open Access Journals (Sweden)

    Francisco Rodríguez

    2015-12-01

    Full Text Available Aim of study: A stem taper function and a compatible merchantable volume system are compared to evaluate which provides a better description of the stem profile for the main species in central Spain.Area of study: This research was carried out in the region of Castile-Leon, located in Central Spain.Material and Methods: A total of 6,357 trees were selected for destructive sampling. All models were fitted using a first-order continuous autoregressive error structure to address the problem of autocorrelation.Main results: In terms of accuracy, the root mean square error (RMSE in both models ranged from 0.75 to 2.72 depending on the species analyzed, presenting values similar to those reported in other studies. Small differences in the goodness-of-fit for both procedures were also found, and the Stud model provided better accuracy for 6 of the 8 species studied, with RMSE reductions of 0.5% to 8.6%. The RMSE obtained in the cross-validation phase was on average 1.22 times higher than what was obtained in the fitting phase.Research highlights: The non-linear extra sum of squares method indicated that the stem taper differs among the five softwood species and three hardwood species. In hardwoods, the first inflection point is lower than in softwoods (at around 5% and the second inflection point is higher (at around 85% than those of softwoods.Keywords: taper function; volume system; Central Spain; softwoods; hardwoods.

  16. Influence of Ply Waviness on Fatigue Life of Tapered Composite Flexbeam Laminates

    Science.gov (United States)

    Murri, Gretchen B.

    1999-01-01

    Nonlinear tapered flexbeam laminates, with significant ply waviness, were cut from a full-size composite rotor hub flexbeam. The specimens were tested under combined axial tension and cyclic bending loads. All of the specimens had wavy plies through the center and near the surfaces (termed marcelled areas), although for some of the specimens the surface marcels were very obvious, and for others they were much smaller. The specimens failed by first developing cracks through the marcels at the surfaces, and then delaminations grew from those cracks, in both directions. Delamination failure occurred in these specimens at significantly shorter fatigue lives than similar specimens without waviness, tested in ref. 2. A 2D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. In addition, the FE model duplicated the waviness observed in one of the test specimens. The model was analyzed using a geometrically nonlinear FE code. Modifications were made to the original model to reduce the amplitude of the marcels near the surfaces. The analysis was repeated for each modification. Comparisons of the interlaminar normal stresses, sigma(sub n), in the various models showed that under combined axial-tension and cyclic-bending loading, for marcels of the same aspect ratio, sigma(sub n) stresses increased as the distance along the taper, from thick to thin end, increased. For marcels of the same aspect ratio and at the same X-location along the taper, sigma(sub n) stresses decreased as the distance from the surface into the flexbeam interior increased. A technique was presented for determining the smallest acceptable marcel aspect ratio at various locations in the flexbeam.

  17. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    Science.gov (United States)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup, Birgitte

    2010-04-01

    High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality. By adapting a bar geometry, the output power could be scaled even up to several tens of watts. Unfortunately, the high divergence which is a characteristic feature of the bar geometry could lead to a degradation of the overall beam quality of the laser bar. However, spectral beam combining is an effective solution for preserving the beam quality of the bar in the range of that of a single emitter and at the same time, enabling the power scaling. We report spectral beam combining applied to a 12 emitter tapered laser bar at 980 nm. The external cavity has been designed for a wavelength separation of 4.0 nm between the emitters. An output power of 9 W has been achieved at an operating current of 30 A. The combined beam had an M2 value (1/e2) of 5.3 along the slow axis which is comparable to that of a single tapered emitter on the laser bar. The overall beam combining efficiency was measured to be 63%. The output spectrum of the individual emitters was narrowed considerably. In the free running mode, the individual emitters displayed a broad spectrum of the order of 0.5-1.0 nm while the spectral width has been reduced to 30-100 pm in the spectral beam combining mode.

  18. High light-extraction-efficiency OLED based on photonic crystal slab structures with taper unit cells

    Institute of Scientific and Technical Information of China (English)

    YAN Rong-jin; WANG Qing-kang

    2006-01-01

    To improve the light-extraction-efficiency of OLED,we introduced PCS (Photonic Crystal Slab) structures into the interface of ITO layer and glass substrate.PCS structures with Taper unit cells are proved to be effective in reducing the energy of guided wave trapped in high refractive index material,and an increase of light-extraction-efficiency to 95.26% is gained.This enhancement is much greater than the traditional PCS with cylinder unit cells (60%-70%).Physical mechanisms of light-extraction-efficiency enhancement in these structures are further discussed.

  19. Plasmon-controlled excitonic emission from vertically-tapered organic nanowires

    Science.gov (United States)

    Chikkaraddy, Rohit; Patra, Partha Pratim; Tripathi, Ravi P. N.; Dasgupta, Arindam; Kumar, G. V. Pavan

    2016-08-01

    Organic molecular nanophotonics has emerged as an important avenue to harness molecular aggregation and crystallization on various functional platforms to obtain nano-optical devices. To this end, there is growing interest to combine organic molecular nanostructures with plasmonic surfaces and interfaces. Motivated by this, herein we introduce a unique geometry: vertically-tapered organic nanowires grown on a plasmonic thin film. A polarization-sensitive plasmon-polariton on a gold thin-film was harnessed to control the exciton-polariton propagation and subsequent photoluminescence from an organic nanowire made of diaminoanthraquinone (DAAQ) molecules. We show that the exciton-polariton emission from individual DAAQ nanowires can be modulated up to a factor of 6 by varying the excitation polarization state of surface plasmons. Our observations were corroborated with full-wave three-dimensional finite-difference time-domain calculations performed on vertically-tapered nanowire geometry. Our work introduces a new optical platform to study coupling between propagating plasmons and propagating excitons, and may have implications in emerging fields such as hybrid-polariton based light emitting devices and vertical-cavity nano-optomechanics.Organic molecular nanophotonics has emerged as an important avenue to harness molecular aggregation and crystallization on various functional platforms to obtain nano-optical devices. To this end, there is growing interest to combine organic molecular nanostructures with plasmonic surfaces and interfaces. Motivated by this, herein we introduce a unique geometry: vertically-tapered organic nanowires grown on a plasmonic thin film. A polarization-sensitive plasmon-polariton on a gold thin-film was harnessed to control the exciton-polariton propagation and subsequent photoluminescence from an organic nanowire made of diaminoanthraquinone (DAAQ) molecules. We show that the exciton-polariton emission from individual DAAQ nanowires can be

  20. High efficiency energy extraction from a relativistic electron beam in a strongly tapered undulator

    CERN Document Server

    Sudar, Nicholas; Duris, Joe; Gadjev, Ivan; Polyaniy, Mikhail; Pogorelsky, Igor; Fedurin, Mikhail; Swinson, Christina; Babzien, Marcus; Kusche, Karl; Gover, Avi

    2016-01-01

    We present results of an experiment where, using a 200 GW CO2 laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54 cm long strongly tapered helical magnetic undulator, extracting over 30$\\%$ of the initial electron beam energy to coherent radiation. These results demonstrate unparalleled electro-optical conversion efficiencies for a relativistic beam in an undulator field and represent an important step in the development of high peak and average power coherent radiation sources.

  1. Capillary electrophoresis in tapered capillary manufactured by etching with sub-supercritical water

    Czech Academy of Sciences Publication Activity Database

    Karásek, Pavel; Horká, Marie; Šlais, Karel; Roth, Michal; Planeta, Josef

    Messina : Chromaleont S.r.L, 2012 - (Sandra, P.; Mondello, L.). s. 254 [International Symposium on Capillary Chromatography /36./ and GC x GC Symposium /9./. 27.5.2012-01.06.2012, Riva del Garda] R&D Projects: GA ČR(CZ) GAP206/11/0138; GA ČR(CZ) GAP106/12/0522; GA MV VG20112015021 Institutional research plan: CEZ:AV0Z40310501 Keywords : electrophoresis in tapered capillaries * supercritical water * complex samples Subject RIV: CB - Analytical Chemistry, Separation

  2. Plasma Etching of Tapered Features in Silicon for MEMS and Wafer Level Packaging Applications

    International Nuclear Information System (INIS)

    This paper is a brief report of plasma etching as applied to pattern transfer in silicon. It will focus more on concept overview and strategies for etching of tapered features of interest for MEMS and Wafer Level Packaging (WLP). The basis of plasma etching, the dry etching technique, is explained and plasma configurations are described elsewhere. An important feature of plasma etching is the possibility to achieve etch anisotropy. The plasma etch process is extremely sensitive to many variables such as mask material, mask openings and more important the plasma parameters

  3. Polarization independent, integrated optical, acoustically tunable wavelength filters/switches with tapered acoustical directional coupler

    Science.gov (United States)

    Herrmann, H.; Schaefer, K.; Sohler, W.

    1994-11-01

    Enhanced sidelobe suppression of the filter characteristics of tunable acousto-optical mode converters in LiNbO3 has been achieved using for the first time tapered acoustical directional couplers. A sidelobe suppression of more than 15.5 dB could be demonstrated in a single stage device. By combining the mode converter with two integrated optical polarization splitters a polarization independent filter/wavelength selective switch has been fabricated with less than 3 dB intrinsic insertion loss, a polarization dependence of less than 1 dB, and a sidelobe suppression exceeding 14 dB.

  4. Chalcogenide Microsphere Fabricated from Fiber Tapers Using Contact With a High-Temperature Ceramic Surface

    OpenAIRE

    Wang, Pengfei; Murugan, Ganapathy; Bramilla, Gilberto; Ding, Ming; Semenova, Yuliya; Wu, Qiang; Farrell, Gerald

    2012-01-01

    The fabrication 1 and characterization of a 2 chalcogenide glass microsphere resonator has been demonstrated. 3 At wavelengths near 1550 nm, whispering gallery mode 4 resonances can be efficiently excited in a 74-μm-diameter 5 chalcogenide glass microsphere via evanescent coupling using a 6 tapered silica glass fiber with a waist diameter of circa 2 μm. 7 Resonances with Q-factors greater than 105 were observed. 8 Due to the high nonlinearity properties of the chalcogenide 9 material and the ...

  5. Power-efficient production of photon pairs in a tapered chalcogenide microwire

    CERN Document Server

    Meyer-Scott, Evan; Ahmad, Raja; Li, Lizhu; Rochette, Martin; Jennewein, Thomas

    2015-01-01

    Using tapered fibers of As2Se3 chalcogenide glass, we produce photon pairs at telecommunication wavelengths with pump power as low as 250 nW for a single pump, and 191 nW for the weak pump in a two-pump non-degenerate scheme. Our results show that the ultrahigh nonlinearity in these microwires could allow single-photon pumping to produce photon pairs, enabling the production of large entangled states, heralding of single photons after lossy transmission, and photonic quantum information processing with nonlinear optics.

  6. High energy supercontinuum sources using tapered photonic crystal fibers for multispectral photoacoustic microscopy

    DEFF Research Database (Denmark)

    Bondu, Magalie; Brooks, Christopher; Jakobsen, Christian;

    2016-01-01

    We demonstrate a record bandwidth high energy supercontinuum source suitable for multispectral photoacoustic microscopy. The source has more than 150  nJ/10  nm150  nJ/10  nm bandwidth over a spectral range of 500 to 1600 nm. This performance is achieved using a carefully designed fiber taper with...... large-core input for improved power handling and small-core output that provides the desired spectral range of the supercontinuum source....

  7. Supercontinuum generation and carrier envelope offset frequency measurement in a tapered single-mode fiber

    CERN Document Server

    Zhang, Long; Zhao, Yanying; Hou, Lei; Yu, Zijiao; Wei, Zhiyi

    2014-01-01

    We report supercontinuum generation by launching femtosecond Yb fiber laser pulses into a tapered single-mode fiber of 3 um core diameter. A spectrum of more than one octave, from 550 to 1400 nm, has been obtained with an output power of 1.3 W at a repetition rate of 250 MHz, corresponding to a coupling efficiency of up to 60%. By using a typical f-2f interferometer, the carrier envelope offset frequency was measured and found to have a signal-to-noise ratio of nearly 30 dB.

  8. Reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of canal preparation

    OpenAIRE

    Amir Abbas Moshari; Nahid Mohammadzadeh Akhlaghi; Nahid Rahimifard; Soheila Darmiani

    2015-01-01

    Aims: The aim of this study was to evaluate the reduction of Enterococcus faecalis in curved root canals after various sizes and tapers of the canal preparation. Materials and Methods: Mandibular first molars (n = 103) with curved mesiobuccal canals were divided into one control (n = 5) and 7 experimental (n = 14) groups, were inoculated with E. faecalis (ATTC 29212) and prepared with the following RaCe files (FKG Dentaire) as master apical file: Groups: 25.04, 25.06, 30.04, 30.06, 35.04,...

  9. Effects of short-term altitude training and tapering on left ventricular morphology in elite swimmers.

    Science.gov (United States)

    Haykowsky, M J; Smith, D J; Malley, L; Norris, S R; Smith, E R

    1998-05-01

    Short or long-term athletic training has been associated with left ventricular (LV) morphological adaptations, including increases in wall thickness, cavity dimension and estimated LV mass. A limitation of previous studies assessing the 'athlete heart' was that exercise training was performed at sea level. Since the 1968 Olympic summer games a popular method of maximizing athletic performance has been to use altitude training (AT) as a means of improving sea level performance. However, the effects of short term AT and taper training on LV morphology have not been well studied. Based on this limitation, the effects of three weeks of intense AT (1848 m) or low level control training (CT) (1050 m) followed by two weeks of taper training were investigated in 15 elite swimmers between 16 and 21 years of age. Short term AT or CT training followed by two weeks of taper training was not associated with alterations in LV diastolic cavity dimension (AT pre 53.3 +/- 2.8 mm versus post 52.6 +/- 4.3 mm; CT pre 52.9 +/- 3.7 mm versus post 51.2 +/- 4.0 mm), ventricular septal wall thickness (AT pre 9.6 +/- 1.0 mm versus post 9.4 +/- 1.1 mm; CT pre 8.4 +/- 1.2 mm versus post 8.6 +/- 1.1 mm), estimated LV mass (AT pre 186.4 +/- 45.8 g versus post 190.0 +/- 48.2 g; CT pre 159.1 +/- 35.8 g versus post 160.1 +/- 40.8 g) or fractional shortening (AT pre 36.8 +/- 3.5% versus post 34.8 +/- 2.7%; CT pre 32.6 +/- 5.0% versus post 32.8 +/- 4.7%). However, a main time effect, independent of training intervention, was observed for posterior wall thickness (pre 8.7 +/- 1.4 mm versus post 9.3 +/- 1.1 mm, P < 0.05). Therefore, with the exception of posterior wall thickness, short term AT followed by two weeks of taper training appears not to be associated with alterations in LV morphology or systolic function. PMID:9627523

  10. Magnetically assisted gas-solid fluidization in a tapered vessel: Part Ⅰ. Magnetization-LAST mode

    Institute of Scientific and Technical Information of China (English)

    Jordan Hristov

    2009-01-01

    This article presents further experimental results of the Magnetization-LAST mode in magnetically assisted gas-fluidized tapered beds, including external transverse magnetic field control of solid phase movement, central channel formation, spout depth and the pressure drop across the bed. Phase diagrams similar to those recently reported for the Magnetization-FIRST mode were also developed. Dimensional analysis based on "pressure transform" of the initial set of variables and involving the magnetic granular Bond number pertinent to particle aggregate formation was applied to develop the scaling relationships.

  11. Note: femtosecond laser micromachining of straight and linearly tapered capillary discharge waveguides.

    Science.gov (United States)

    Wiggins, S M; Reijnders, M P; Abuazoum, S; Hart, K; Welsh, G H; Issac, R C; Jones, D R; Jaroszynski, D A

    2011-09-01

    Gas-filled capillary discharge waveguides are important structures in laser-plasma interaction applications, such as the laser wakefield accelerator. We present the methodology for applying femtosecond laser micromachining in the production of capillary channels (typically 200-300 μm in diameter and 30-40 mm in length), including the formalism for capillaries with a linearly tapered diameter. The latter is demonstrated to possess a smooth variation in diameter along the length of the capillary (tunable with the micromachining trajectories). This would lead to a longitudinal plasma density gradient in the waveguide that may dramatically improve the laser-plasma interaction efficiency in applications. PMID:21974631

  12. Note: Efficient generation of optical sidebands at GHz with a high-power tapered amplifier

    International Nuclear Information System (INIS)

    Two methods using a laser-diode tapered amplifier to produce high-power, high-efficiency optical frequency sidebands over a wide tunable frequency range are studied and compared. For a total output of 500 mW at 811 nm, 20% of the power can be placed in each of the first-order sidebands. Functionality and characterization are presented within the sideband frequency region of 0.8–2.3 GHz, and it is shown that both methods can be applied beyond this frequency range. These methods provide a versatile and effective tool for atomic physics experiments

  13. A Study of the Anechoic Performance of Rice Husk-Based, Geometrically Tapered, Hollow Absorbers

    OpenAIRE

    Muhammad Nadeem Iqbal; Mohd. Fareq Malek; Yeng Seng Lee; Liyana Zahid; Muhammad Shafiq Mezan

    2014-01-01

    Although solid, geometrically tapered microwave absorbers are preferred due to their better performance, they are bulky and must have a thickness on the order of λ or more. The goal of this study was to design lightweight absorbers that can reduce the electromagnetic reflections to less than −10 dB. We used a very simple approach; two waste materials, that is, rice husks and tire dust in powder form, were used to fabricate two independent samples. We measured and used their dielectric propert...

  14. Highly sensitive evanescent wave combination tapered fiber optic fluorosensor for protein detection

    Science.gov (United States)

    Nardone, Vincent; Kapoor, Rakesh

    2008-02-01

    In this paper we are reporting the development of a highly sensitive evanescent wave combination tapered fiber optic fluorosensor. We have demonstrated detection of 5 pM Bovine Serum Albumin (BSA) protein using these fiber optic sensors. The sensor can be easily adopted for detection of other proteins. Six identical probes were prepared and affinity pure Goat anti-BSA antibodies were immobilized on the probe surface. We could detect signal from all the probes kept in 5 pM to 1 nM BSA solution while no signal was detected from the probes kept in 20 nM labeled ESA solution.

  15. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers

    DEFF Research Database (Denmark)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin;

    2011-01-01

    output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2- values of the laser with lowest spatial coherence. The principle of......Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest...... spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future....

  16. k-space Imaging of the Eigenmodes of Sharp Gold Tapers for Scanning Near-Field Optical Microscopy

    CERN Document Server

    Esmann, Martin; da Cunha, Bernard B; Brauer, Jens H; Vogelgesang, Ralf; Gross, Petra; Lienau, Christoph

    2013-01-01

    We investigate the radiation patterns of sharp conical gold tapers, designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM). Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the generation of strongly enhanced near-field signals. Higher order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate between the lowest and higher order eigenmodes of such a metallic taper by filtering in the spatial frequency domain. Our approach has the potential to considerably improve the signal-to-background ratio in spectroscopic experiments on the nanoscale.

  17. k-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy

    Directory of Open Access Journals (Sweden)

    Martin Esmann

    2013-10-01

    Full Text Available We investigate the radiation patterns of sharp conical gold tapers, which were designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM. Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the generation of strongly enhanced near-field signals. Higher-order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate between the lowest and higher-order eigenmodes of such a metallic taper by filtering in the spatial frequency domain. Our approach has the potential to considerably improve the signal-to-background ratio in spectroscopic experiments at the nanoscale.

  18. Body punk

    DEFF Research Database (Denmark)

    Mogensen, Kevin

    BODYPUNK - A Treatise on male body builders and the meaning of the body in the shadow of an Anti Doping Campaign Based on a qualitative study, the thesis investigates the visual representation of the male bodybuilder found in the national anti doping campaign: ‗ "The hunt has begun" along with an...... analysis of the embodied meaning of men‘s bodybuilding....

  19. Body Weight and Body Image

    OpenAIRE

    McFarlane Traci; Olmsted Marion P

    2004-01-01

    Abstract Health Issue Body weight is of physical and psychological importance to Canadian women; it is associated with health status, physical activity, body image, and self-esteem. Although the problems associated with overweight and obesity are indeed serious, there are also problems connected to being underweight. Weight prejudice and the dieting industry intensify body image concerns for Canadian women and can have a major negative impact on self-esteem. Key Findings Women have lower BMIs...

  20. Development of a Compatible Taper Function and Stand-Level Merchantable Volume Model for Chinese Fir Plantations

    Science.gov (United States)

    Tang, Xiaolu; Pérez-Cruzado, César; Fehrmann, Lutz; Álvarez-González, Juan Gabriel; Lu, Yuanchang; Kleinn, Christoph

    2016-01-01

    Chinese fir (Cunninghamia lanceolata [Lamb.] Hook) is one of the most important plantation tree species in China with good timber quality and fast growth. It covers an area of 8.54 million hectare, which corresponds to 21% of the total plantation area and 32% of total plantation volume in China. With the increasing market demand, an accurate estimation and prediction of merchantable volume at tree- and stand-level is becoming important for plantation owners. Although there are many studies on the total tree volume estimation from allometric models, these allometric models cannot predict tree- and stand-level merchantable volume at any merchantable height, and the stand-level merchantable volume model was not seen yet in Chinese fir plantations. This study aimed to develop (1) a compatible taper function for tree-level merchantable volume estimation, and (2) a stand-level merchantable volume model for Chinese fir plantations. This “taper function system” consisted in a taper function, a merchantable volume equation and a total tree volume equation. 46 Chinese fir trees were felled to develop the taper function in Shitai County, Anhui province, China. A second-order continuous autoregressive error structure corrected the inherent serial autocorrelation of different observations in one tree. The taper function and volume equations were fitted simultaneously after autocorrelation correction. The compatible taper function fitted well to our data and had very good performances in diameter and total tree volume prediction. The stand-level merchantable volume equation based on the ratio approach was developed using basal area, dominant height, quadratic mean diameter and top diameter (ranging from 0 to 30 cm) as independent variables. At last, a total stand-level volume table using stand basal area and dominant height as variables was proposed for local forest managers to simplify the stand volume estimation. PMID:26799399

  1. Plasmon-controlled excitonic emission from vertically-tapered organic nanowires.

    Science.gov (United States)

    Chikkaraddy, Rohit; Patra, Partha Pratim; Tripathi, Ravi P N; Dasgupta, Arindam; Kumar, G V Pavan

    2016-08-21

    Organic molecular nanophotonics has emerged as an important avenue to harness molecular aggregation and crystallization on various functional platforms to obtain nano-optical devices. To this end, there is growing interest to combine organic molecular nanostructures with plasmonic surfaces and interfaces. Motivated by this, herein we introduce a unique geometry: vertically-tapered organic nanowires grown on a plasmonic thin film. A polarization-sensitive plasmon-polariton on a gold thin-film was harnessed to control the exciton-polariton propagation and subsequent photoluminescence from an organic nanowire made of diaminoanthraquinone (DAAQ) molecules. We show that the exciton-polariton emission from individual DAAQ nanowires can be modulated up to a factor of 6 by varying the excitation polarization state of surface plasmons. Our observations were corroborated with full-wave three-dimensional finite-difference time-domain calculations performed on vertically-tapered nanowire geometry. Our work introduces a new optical platform to study coupling between propagating plasmons and propagating excitons, and may have implications in emerging fields such as hybrid-polariton based light emitting devices and vertical-cavity nano-optomechanics. PMID:27444822

  2. Tunable tapered waveguide for efficient compression of light to graphene surface plasmons

    Science.gov (United States)

    Cheng, Bo Han; Chen, Hong Wen; Jen, Yi-Jun; Lan, Yung-Chiang; Tsai, Din Ping

    2016-01-01

    Dielectric-graphene-dielectric (DGD) structure has been widely used to construct optical devices at infrared region with features of small footprint and low-energy dissipation. The optical properties of graphene can be manipulated by changing its chemical potential by applying a biased voltage onto graphene. However, the excitation efficiency of surface wave on graphene by end-fire method is very low because of large wavevector mismatch between infrared light and surface wave. In this paper, a dielectric-semiconductor-dielectric (DSD) tapered waveguide with magnetic tunability for efficient excitation of surface waves on DGD at infrared region is proposed and analyzed. Efficient excitation of surface waves on DGD with various chemical potentials in graphene layer and incident frequencies can be attained by merely changing the external magnetic field applied onto the DSD tapered waveguide. The electromagnetic simulations verify the design of the proposed structure. More importantly, the constituent materials used in the proposed structure are available in nature. This work opens the door toward various applications in the field of using surface waves. PMID:27353171

  3. The visibility based Tapered Gridded Estimator (TGE) for the redshifted 21-cm power spectrum

    CERN Document Server

    Choudhuri, Samir; Chatterjee, Suman; Ali, Sk Saiyad; Roy, Nirupam; Ghosh, Abhik

    2016-01-01

    We present the improved visibility based Tapered Gridded Estimator (TGE) for the power spectrum of the diffuse sky signal. The visibilities are gridded to reduce the computation, and tapered through a convolution to suppress the contribution from the outer regions of the telescope's field of view. The TGE also internally estimates the noise bias, and subtracts this out to give an unbiased estimate of the power spectrum. An earlier version of the 2D TGE for the angular power spectrum $C_{\\ell}$ is improved and then extended to obtain the 3D TGE for the power spectrum $P({\\bf k})$ of the 21-cm brightness temperature fluctuations. Analytic formulas are also presented for predicting the variance of the binned power spectrum. The estimator and its variance predictions are validated using simulations of $150 \\, {\\rm MHz}$ GMRT observations. We find that the estimator accurately recovers the input model for the 1D Spherical Power Spectrum $P(k)$ and the 2D Cylindrical Power Spectrum $P(k_\\perp,k_\\parallel)$, and the...

  4. Survival Rate of Short, Locking Taper Implants with a Plateau Design: A 5-Year Retrospective Study

    Directory of Open Access Journals (Sweden)

    Kemal Özgür Demiralp

    2015-01-01

    Full Text Available Background. Short implants have become popular in the reconstruction of jaws, especially in cases with limited bone height. Shorter implants, those with locking tapers and plateau root shapes, tend to have longer survival times. We retrospectively investigated the cumulative survival rates of Bicon short implants (<8 mm according to patient variables over a 5-year period. Materials and Methods. This study included 111 consecutively treated patients with 371 implants supporting fixed or removable prosthetics. Data were evaluated to acquire cumulative survival rates according to gender, age, tobacco use, surgical procedure, bone quality, and restoration type. Statistics were performed using chi-square, Mann-Whitney, and Kruskal Wallis H tests. Results. The survival rate was 97.3% with, on average, 22.8 months of follow-up. Patients older than 60 years had higher failure rate than the other age groups (P<0.05. Placed region, age, and bone quality had adverse effects on survival rate in the <8 mm implant group with statistically significant difference (P<0.05. Conclusions. Approximately 23-month follow-up data indicate that short implants with locking tapers and plateau-type roots have comparable survival rates as other types of dental implants. However, due to limitations of study, these issues remain to be further investigated in future randomized controlled clinical trials.

  5. Does offshore crustal taper control an onshore topographic displacement gradient in SE Brasil?

    Science.gov (United States)

    Redfield, Tim; Terje Osmundsen, Per; Peron-Pinvidic, Gwenn

    2015-04-01

    The SE Brasilian Serras da Mantiqueira and do Mar topographic envelopes exhibit coast-parallel displacement gradients typical of linked normal faults in extending terrain. Between southern Curitiba and Cabo Frio, coast-perpendicular profiles show the distance from the maximum escarpment elevation to the likely location of the extended margin's flexural/rheological coupling point (Taper Break, or TB) is inversely correlative to the height of the escarpment. The correlation is similar to previously-published scaling relationships derived from Scandinavian and global datasets. Although Precambrian ductile shear zones guided brittle phase faulting during Mesozoic extension and Cenozoic margin uplift, the primary control governing fault reactivation and source-to-sink evolution of the SE Brasilian rifted margin seems rooted in crustal thinning. We see two lines of interest for petroleum exploration: Preferential reactivation of high angle faults at sharply-tapered margin sectors is expected to guide onshore to offshore sediment routing along margin-parallel corridors, and (should the TB-escarpment correlation be better validated with proposed analyses of high-quality marine geophysical datasets) a partial constraint upon architectural end member interpretations of deep crustal structure may be contemplated.

  6. Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

    Science.gov (United States)

    Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

    2015-08-12

    Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples. PMID:26186260

  7. Structural health monitoring of constrained tapered beamlike structures using natural frequencies and nodal points

    International Nuclear Information System (INIS)

    The integrity and safety of beam-like structures are dependent in part on their boundary conditions which can vary with time due to damage or aging. Structural health monitoring of such structures should therefore include attention to boundary conditions. Where the boundary conditions can be represented by a lumped spring then the identification of associated stiffness parameter values may be a means to quantifying the integrity of the support. This paper investigates such a method for identifying the equivalent translational and rotational stiffness of a constrained tapered beam-like structure. An analytical model of a beam of tapered width and thickness is adopted as a simplified representation of a tower-like structure. The model is used to explore in what scenarios natural frequencies and/or nodal points might be sufficiently sensitive to changes in support conditions to be measurable indicators of damage. The method is evaluated by Monte Carlo simulations for a numerical example where the severity of noise can be controlled.

  8. Exact solutions for coupled free vibrations of tapered shear-flexible thin-walled composite beams

    Science.gov (United States)

    Piovan, Marcelo T.; Filipich, Carlos P.; Cortínez, Víctor H.

    2008-09-01

    In this paper, analytical solutions for the free vibration analysis of tapered thin-walled laminated-composite beams with both closed and open cross-sections are developed. The present study is based on a recently developed model that incorporates in a full form the shear flexibility. The model considers shear flexibility due to bending as well as warping related to non-uniform torsion. The theory is briefly reviewed with the aim to present the equilibrium equations, the related boundary conditions and the constitutive equations. The stacking sequences in the panels of the cross-sections are selected in order to behave according to certain elastic coupling features. Typical laminations for a box-beam such as circumferentially uniform stiffness (CUS) or circumferentially asymmetric stiffness (CAS) configurations are adopted. For open cross-sections, special laminations behaving elastically like the CAS and CUS configurations of closed sections are also taken into account. The exact values (i.e. with arbitrary precision) of frequencies are obtained by means of a generalized power series methodology. A recurrence scheme is introduced with the aim to simplify the algebraic manipulation by shrinking the number of unknown variables. A parametric analysis for different taper ratios, slenderness ratios and stacking sequences is performed. Numerical examples are also carried out focusing attention in the validation of the present theory with respect to 2D FEM computational approaches, as well as to serve as quality test and convergence test of former finite elements schemes.

  9. Torsional Vibrations of a Conic Shaft with Opposite Tapers Carrying Arbitrary Concentrated Elements

    Directory of Open Access Journals (Sweden)

    Jia-Jang Wu

    2013-01-01

    Full Text Available The purpose of this paper is to present the exact solution for free torsional vibrations of a linearly tapered circular shaft carrying a number of concentrated elements. First of all, the equation of motion for free torsional vibration of a conic shaft is transformed into a Bessel equation, and, based on which, the exact displacement function in terms of Bessel functions is obtained. Next, the equations for compatibility of deformations and equilibrium of torsional moments at each attaching point (including the shaft ends between the concentrated elements and the conic shaft with positive and negative tapers are derived. From the last equations, a characteristic equation of the form is obtained. Then, the natural frequencies of the torsional shaft are determined from the determinant equation , and, corresponding to each natural frequency, the column vector for the integration constants, , is obtained from the equation . Substitution of the last integration constants into the associated displacement functions gives the corresponding mode shape of the entire conic shaft. To confirm the reliability of the presented theory, all numerical results obtained from the exact method are compared with those obtained from the conventional finite element method (FEM and good agreement is achieved.

  10. Demonstration of large electron-beam energy extraction by a tapered-wiggler free-electron laser

    International Nuclear Information System (INIS)

    Electron-beam energy spectral measurements were made on a tapered-wiggler free-electron laser amplifier. A 10 MeV electron beam from a traveling-wave linear accelerator interacted in a tapered-wiggler with an intense 10.6μm CO/sub 2/ laser beam. The electron spectra show a 4 percent net energy loss and a 9 percent peak loss. Measurements of electron energy spectra, extraction efficiency as a function of electron-beam energy, and extraction efficiency as a function of optical power are presented and are consistent with theoretically predicted performance

  11. Coupling Single-Mode Fiber to Uniform and Symmetrically Tapered Thin-Film Waveguide Structures Using Gadolinium Gallium Garnet

    Science.gov (United States)

    Gadi, Jagannath; Yalamanchili, Raj; Shahid, Mohammad

    1995-01-01

    The need for high efficiency components has grown significantly due to the expanding role of fiber optic communications for various applications. Integrated optics is in a state of metamorphosis and there are many problems awaiting solutions. One of the main problems being the lack of a simple and efficient method of coupling single-mode fibers to thin-film devices for integrated optics. In this paper, optical coupling between a single-mode fiber and a uniform and tapered thin-film waveguide is theoretically modeled and analyzed. A novel tapered structure presented in this paper is shown to produce perfect match for power transfer.

  12. Cross two photon absorption in a silicon photonic crystal waveguide fiber taper coupler with a physical junction

    International Nuclear Information System (INIS)

    Cross two photon absorption in silicon is characterized using a tapered fiber photonic crystal silicon waveguide coupler. There is a physical junction between the tapered fiber and the waveguide constituting a stand-alone device. This device is used to obtain the spectrum for cross two photon absorption coefficient per unit volume of interaction between photons of nondegenerate energy. The corresponding Kerr coefficient per unit volume of interaction is also experimentally extracted. The thermal resistance of the device is also experimentally determined and the response time of the device is estimated for on-chip all-optical signal processing and data transfer between optical signals of different photon energies

  13. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers

    OpenAIRE

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E.; Petersen, Paul Michael

    2011-01-01

    Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and...

  14. Design of Highly Efficient Hybrid Si-Au Taper for Dielectric Strip Waveguide to Plasmonic Slot Waveguide Mode Converter

    CERN Document Server

    Chen, Chin-Ta; Hosseini, Amir; Pan, Zeyu; Subbaraman, Harish; Zhang, Xingyu; Chen, Ray T

    2015-01-01

    In this paper, we design a dielectric-to-plasmonic slot waveguide mode converter based on the hybrid silicon-gold taper. The effects of mode matching, the effective index matching, and the metallic absorption loss on the conversion efficiency are studied. Consequently, a metallic taper-funnel coupler with an overall length of 1.7um is designed to achieve a very high conversion efficiency of 93.3% at 1550 nm. The configuration limitations for not allowing this mode converter to achieve a 100% conversion efficiency are also investigated. Such a high-efficiency converter can provide practical routes to realize ultracompact integrated circuits.

  15. Design and performance analysis of InP/InGaAsP-MMI based 1310/1550-nm wavelength division demultiplexer with tapered waveguide geometry

    Science.gov (United States)

    Chack, D.; Kumar, V.; Raghuwanshi, S. K.

    2015-12-01

    The design and performance analysis of a 1310/1550-nm wavelength division demultiplexer with tapered geometry based on InP/InGaAsP multimode interference (MMI) coupler has been carried out. Wavelength response of demultiplexer of conventional MMI and tapered input and tapered output (tapered I/O) waveguides geometry of the MMI have been discussed. The demultiplexing function has been first performed by choosing a suitable refractive index of the guiding region and geometrical parameters such as the width and length of MMI structure have been achieved. Access width of tapered I/O waveguides have been adjusted to give a low insertion loss (IL) and high extinction ratio (ER) for the considered wavelengths of 1310 nm and 1550 nm. The total size of the demultiplexer has been significantly reduced over the existing MMI devices. Numerical simulations with finite difference beam propagation method are applied to design and optimize the operation of the proposed demultiplexer.

  16. Body lice

    Science.gov (United States)

    Lice - body; Pediculosis corporis; Vagabond disease ... Diaz JH. Lice (pediculosis). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases . 8th ...

  17. Bog bodies

    DEFF Research Database (Denmark)

    Lynnerup, Niels

    2015-01-01

    the bog bodies have been studied using medical and natural scientific methods, and recently many bog bodies have been re-examined using especially modern, medical imaging techniques. Because of the preservation of soft tissue, especially the skin, it has been possible to determine lesions and trauma......In northern Europe during the Iron Age, many corpses were deposited in bogs. The cold, wet and anaerobic environment leads in many cases to the preservation of soft tissues, so that the bodies, when found and excavated several thousand years later, are remarkably intact. Since the 19th century....... Conversely, the preservation of bones is less good, as the mineral component has been leached out by the acidic bog. Together with water-logging of collagenous tissue, this means that if the bog body is simply left to dry out when found, as was the case pre-19th century, the bones may literally warp...

  18. Strain analysis of different diameter Morse taper implants under overloading compressive conditions

    Directory of Open Access Journals (Sweden)

    Carolina Guimarães CASTRO

    2015-01-01

    Full Text Available The aim of this study was to evaluate the amount of deformation from compression caused by different diameters of Morse taper implants and the residual deformation after load removal. Thirty Morse taper implants lacking external threads were divided into 3 groups (n = 10 according to their diameter as follows: 3.5 mm, 4.0 mm and 5.0 mm. Two-piece abutments were fixed into the implants, and the samples were subjected to compressive axial loading up to 1500 N of force. During the test, one strain gauge remained fixed to the cervical portion of each implant to measure the strain variation. The strain values were recorded at two different time points: at the maximum load (1500 N and 60 seconds after load removal. To calculate the strain at the implant/abutment interface, a mathematical formula was applied. Data were analyzed using a one-way Anova and Tukey’s test (α = 0.05. The 5.0 mm diameter implant showed a significantly lower strain (650.5 μS ± 170.0 than the 4.0 mm group (1170.2 μS ± 374.7 and the 3.5 mm group (1388.1 μS ± 326.6 (p < 0.001, regardless of the load presence. The strain values decreased by approximately 50% after removal of the load, regardless of the implant diameter. The 5.0 mm implant showed a significantly lower strain at the implant/abutment interface (943.4 μS ± 504.5 than the 4.0 mm group (1057.4 μS ± 681.3 and the 3.5 mm group (1159.6 μS ± 425.9 (p < 0.001. According to the results of this study, the diameter influenced the strain around the internal and external walls of the cervical region of Morse taper implants; all diameters demonstrated clinically acceptable values of strain.

  19. Costs and constraints conspire to produce honest signaling

    DEFF Research Database (Denmark)

    Holman, Luke

    2012-01-01

    Signal costs and evolutionary constraints have both been proposed as ultimate explanations for the ubiquity of honest signaling, but the interface between these two factors is unclear. Here, I propose a pluralistic interpretation, and use game theory to demonstrate that evolutionary constraints...... determine whether signals evolve to be costly or cheap. Specifically, when the costs or benefits of signaling are strongly influenced by the sender's quality, low-cost signals evolve. The model reaffirms that cheap and costly signals can both be honest, and predicts that expensive signals should have more...

  20. Astrocytes conspire with neurons during progression of neurological disease

    OpenAIRE

    McGann, James C.; Lioy, Daniel T.; Mandel, Gail

    2012-01-01

    As astrocytes are becoming recognized as important mediators of normal brain function, studies into their roles in neurological disease have gained significance. Across mouse models for neurodevelopmental and neurodegenerative diseases, astrocytes are considered key regulators of disease progression. In Rett syndrome and Parkinson’s disease, astrocytes can even initiate certain disease phenotypes. Numerous potential mechanisms have been offered to explain these results, but research into the ...

  1. Simulation of the Second Grade Fluid Model for Blood Flow through a Tapered Artery with a Stenosis

    Science.gov (United States)

    Nadeem, S.; Noreen Sher, Akbar

    2010-06-01

    We analyze the blood flow through a tapered artery, assuming the blood to be a second order fluid model. The resulting nonlinear implicit system of partial differential equations is solved by the perturbation method. The expressions for shear stress, velocity, flow rate, wall shear stress and longitudinal impedance are obtained. The physical behavior of different parameters is also discussed, as are trapping phenomena.

  2. 76 FR 43262 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2011-07-20

    ...: Initiation of Antidumping Duty New Shipper Review, 76 FR 6397 (February 4, 2011). On June 17, 2011, the... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the... (``NSR'') of Xiang Yang Automobile Bearing Co., Ltd. (``ZXY'').\\1\\ We gave interested parties...

  3. 77 FR 65668 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2012-10-30

    ... Shipper Review, 77 FR 32522 (June 1, 2012) (``Preliminary Results''). FOR FURTHER INFORMATION CONTACT... eligible for a separate rate. \\9\\ See Preliminary Results, 77 FR at 32523-24. Final Results of the New... International Trade Administration Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From...

  4. 76 FR 72213 - Tapered Roller Bearings From China; Notice of Commission determination To Conduct a Full Five...

    Science.gov (United States)

    2011-11-22

    ... part 201), and part 207, subparts A, D, E, and F (19 CFR part 207), as amended, 76 FR 61937 (October 6... responses to its notice of institution (76 FR 45853, August 1, 2011) were adequate.\\2\\ A record of the... COMMISSION Tapered Roller Bearings From China; Notice of Commission determination To Conduct a Full...

  5. A Sensitivity-Enhanced Refractive Index Sensor Using a Single-Mode Thin-Core Fiber Incorporating an Abrupt Taper

    Directory of Open Access Journals (Sweden)

    Jie Shi

    2012-04-01

    Full Text Available A sensitivity-enhanced fiber-optic refractive index (RI sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF between two sections of single-mode fibers (SMFs. The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI. An abrupt taper (tens of micrometers long made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

  6. Tunable and switchable dual-wavelength mode-locked Tm3+-doped fiber laser based on a fiber taper.

    Science.gov (United States)

    Wang, Yazhou; Li, Jianfeng; Zhai, Bo; Hu, Yunxiao; Mo, Kundong; Lu, Rongguo; Liu, Yong

    2016-07-11

    We demonstrate a self-starting dual-wavelength mode-locked fiber laser at a 2 μm spectral region by using a fiber taper in a Tm3+-doped ring fiber cavity. The fiber taper fabricated with a flame brushing technique was used as a periodic filter with a modulation depth of ~3.61 dB and a modulation period of ~7.3 nm, respectively. Diverse dual-wavelength regimes including continuous wave (CW)/multi-soliton, soliton/multi-soliton, and soliton/soliton regimes were obtained by adjusting pump power. Wavelength tuning for the dual-wavelength was also precisely controllable through stretching the fiber taper carefully. The tuning range was ~7 nm which was limited by the modulation period of the taper. By inserting a 10.0 m dispersion compensation fiber (DCF) into the fiber cavity, a stable dual-wavelength dissipative-soliton operation was obtained at 2 μm spectral region for the first time. PMID:27410806

  7. The effect of root canal taper on the irrigant flow: evaluation using an unsteady Computational Fluid Dynamics model

    NARCIS (Netherlands)

    C. Boutsioukis; C. Gogos; B. Verhaagen; M. Versluis; E. Kastrinakis; L.W.M. van der Sluis

    2010-01-01

    Aim  To evaluate the effect of root canal taper on irrigant flow inside a prepared root canal during final irrigation with a syringe and two types of needles, using a Computational Fluid Dynamics (CFD) model. Methodology  A validated CFD model was used to simulate irrigant flow from either a side-ve

  8. The effect of root canal taper on the irrigant flow: evaluation using an unsteady Computational Fluid Dynamics model

    NARCIS (Netherlands)

    Boutsioukis, C.; Gogos, C.; Verhaagen, B.; Versluis, M.; Kastrinakis, E.; Sluis, van der L.W.M.

    2010-01-01

    Aim  To evaluate the effect of root canal taper on irrigant flow inside a prepared root canal during final irrigation with a syringe and two types of needles, using a Computational Fluid Dynamics (CFD) model. Methodology  A validated CFD model was used to simulate irrigant flow from either a side-v

  9. The measurement of sucrose concentration by two-tapered all-fiber Mach-Zehnder interferometer employing different coupling structures and manufacture processes

    Science.gov (United States)

    Zhu, Yu-Sheng; Wang, Hsin-Wen; Hsu, Yi-Cheng

    2016-08-01

    The sucrose concentration measurement and characteristics of light coupling taper structure on sensitivity with various fabrication processes of taper structure for all-fiber Mach-Zehnder interferometer (AFMZI) are presented. Using fusion splicer with electrical discharge, the standard single-mode fiber is employed to be fabricated as conical coupling/decoupling taper structure. The basic two fabrication processes are designed as single fusion-stretching (SFS), multiple fusions without stretching (MF). The third advanced process is composed of SFS and multiple fusions without stretching processes, and called multiple fusions with single stretching (MFSS). Various types of coupling/decoupling taper structures were fabricated based on the three kinds of fabrication processes. The effects of geometry shape including taper waist, taper angle, and sensing length on sensing sensitivity of AFMZIs are estimated. The modifications of fiber core and cladding induced by thermal effect affect the refractive index distributions and shapes of taper structure. The effects of refractive index changes of fiber core and cladding on sensing sensitivity are also discussed. The AFMZI was tested by measuring aqueous sucrose solution of refractive index unit (RIU) from 1.333 to 1.420 RIU. The optical spectrums are measured by a spectrometer. The spectrum dip shifts and sensing sensitivity was measured and calculated, respectively. As shown in results, sensing sensitivities of AFMZIs of taper structure fabricated by MFSS and multiple fusions without stretching processing are generally higher than SFS. The reasons could be aimed on materials modification through thermal effect on blurring fiber core-cladding interface and proper taper angle of taper structure. The more homogeneous refractive index distribution on fiber core-cladding interface, the more detecting light power decoupled through core-cladding interface to interact with exterior environment and enhance the sensing sensitivity

  10. Tapered fused-bundle splitter capable of 1kW CW operation

    Science.gov (United States)

    Wetter, Alexandre; Faucher, Mathieu; Lovelady, Michael; Séguin, François

    2007-02-01

    In order to test power-handling at 1kW, a special splitter component had to be developed to make use of available sources. A tapered fused-bundle (TFB) 1X7 splitter using a 1.00mm core diameter 0.22NA input fiber coupled to seven 400 micron core 0.22 NA output fibers was tested up to 860W at 976nm. Surface temperature rise was measured to be less than 15°C with active heat sinking. The above results suggest that understanding the mechanisms of optical loss for forward and backward propagating light in a TFB and the heat load that these losses generate is the key to producing multi kW components, and demonstrates that reliable kW-level all fiber devices are possible.

  11. Mathematical modelling of blood flow through a tapered overlapping stenosed artery with variable viscosity

    CERN Document Server

    Shit, G C; Sinha, A

    2012-01-01

    This paper presents a theoretical study of blood flow through a tapered and overlapping stenosed artery under the action of an externally applied magnetic field. The fluid (blood) medium is assumed to be porous in nature. The variable viscosity of blood depending on hematocrit (percentage volume of erythrocytes) is taken into account in order to improve resemblance to the real situation. The governing equation for laminar, incompressible and Newtonian fluid subject to the boundary conditions is solved by using a well known Frobenius method. The analytical expressions for velocity component, volumetric flow rate, wall shear stress and pressure gradient are obtained. The numerical values are extracted from these analytical expressions and are presented graphically. It is observed that the influence of hematocrit, magnetic field and the shape of artery have important impact on the velocity profile, pressure gradient and wall shear stress. Moreover, the effect of primary stenosis on the secondary one has been sig...

  12. Mathematical Modelling of Blood Flow through a Tapered Overlapping Stenosed Artery with Variable Viscosity

    Directory of Open Access Journals (Sweden)

    G. C. Shit

    2014-01-01

    Full Text Available This paper presents a theoretical study of blood flow through a tapered and overlapping stenosed artery under the action of an externally applied magnetic field. The fluid (blood medium is assumed to be porous in nature. The variable viscosity of blood depending on hematocrit (percentage volume of erythrocytes is taken into account in order to improve resemblance to the real situation. The governing equation for laminar, incompressible and Newtonian fluid subject to the boundary conditions is solved by using a well known Frobenius method. The analytical expressions for velocity component, volumetric flow rate, wall shear stress and pressure gradient are obtained. The numerical values are extracted from these analytical expressions and are presented graphically. It is observed that the influence of hematocrit, magnetic field and the shape of artery have important impact on the velocity profile, pressure gradient and wall shear stress. Moreover, the effect of primary stenosis on the secondary one has been significantly observed.

  13. Packaged silica microsphere-taper coupling system for robust thermal sensing application.

    Science.gov (United States)

    Yan, Ying-Zhan; Zou, Chang-Ling; Yan, Shu-Bin; Sun, Fang-Wen; Ji, Zhe; Liu, Jun; Zhang, Yu-Guang; Wang, Li; Xue, Chen-Yang; Zhang, Wen-Dong; Han, Zheng-Fu; Xiong, Ji-Jun

    2011-03-28

    We propose and realize a novel packaged microsphere-taper coupling structure (PMTCS) with a high quality factor (Q) up to 5×10(6) by using the low refractive index (RI) ultraviolet (UV) glue as the coating material. The optical loss of the PMTCS is analyzed experimentally and theoretically, which indicate that the Q is limited by the glue absorption and the radiation loss. Moreover, to verify the practicability of the PMTCS, thermal sensing experiments are carried out, showing the excellent convenience and anti-jamming ability of the PMTCS with a high temperature resolution of 1.1×10(-3) ◦C. The experiments also demonstrate that the PMTCS holds predominant advantages, such as the robustness, mobility, isolation, and the PMTCS can maintain the high Q for a long time. The above advantages make the PMTCS strikingly attractive and potential in the fiber-integrated sensors and laser. PMID:21451600

  14. Properties of fast carbon cluster microbeams produced with a tapered capillary

    International Nuclear Information System (INIS)

    We study the transmission properties of fast cluster ions (Cn+ (n = 2–4) with velocities ranging from 0.89 to 1.79 a.u.) through a single tapered capillary with an outlet diameter of 13.7 μm. We investigate the projectile-velocity dependence of the transmission fraction from the measurements of transmitted particle energy spectra. It is found that the non-fragmentation fraction of C2+ projectiles increases with decreasing velocity, indicating that fragmentation occurs mainly via close collisions with the surfaces of the capillary wall. For Cn+ (n = 2–4) ions with the same incident velocity, the cluster-size dependence of the non-fragmentation fraction shows even–odd alternation, implying that the fraction includes contributions from stable clusters surviving the grazing scattering process at the capillary surface. We also find that the angular distribution of transmitted particles is narrower for cluster projectiles compared with atomic projectiles.

  15. Multi-cell disk-and-ring tapered structure for compact RF linacs

    Science.gov (United States)

    Smirnov, A. V.; Boucher, S.; Kutsaev, S.; Hartzell, J.; Savin, E.

    2016-09-01

    A tubular disk-and-ring, tapered accelerating structure for small electron linacs and MicroLinacs is considered. It consists of metal and dielectric elements inserted into a metallic tube to eliminate multi-cell, multi-step brazing. The structure enables a wide range of phase velocities (including non-relativistic), a wide bandwidth allowing large number of cells (for standing wave mode) or short filling time (for traveling wave mode), combination of compensated and purely π-mode cells, alternative periodic focusing built-in to the RF structure (the disks), and combining of RF and vacuum windows. RF and accelerating performance of such a long structure having up to four dozens cells is analyzed. Some of beam dynamics, thermal, and vacuum aspects of the structure and MicroLinac performance are considered as well.

  16. All fiber magnetic field sensor with Ferrofluid-filled tapered microstructured optical fiber interferometer.

    Science.gov (United States)

    Deng, Ming; Huang, Can; Liu, Danhui; Jin, Wei; Zhu, Tao

    2015-08-10

    An ultra-compact optical fiber magnetic field sensor based on a microstructured optical fiber (MOF) modal interference and ferrofluid (FF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing a tapered germanium-doped index guided MOF with six big holes injected with FF to two conventional single-mode fibers. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. Due to an efficient interaction between the magnetic nanoparticles in FF and the excited cladding mode, the magnetic field sensitivity reaches up to117.9pm/mT with a linear range from 0mT to 30mT. Moreover, the fabrication process of the proposed sensor is simple, easy and cost-effective. Therefore, it will be a promising candidate for military, aviation industry, and biomedical applications, especially, for the applications where the space is limited. PMID:26367919

  17. FEM simulation of tapered cap floating sleeve antenna for hepatocellular carcinoma therapy.

    Science.gov (United States)

    Maini, Surita

    2016-01-01

    Malignant liver tumors are the sixth most common and deadly cancer in the world and the third most common cause of cancer mortality. Hepatocellular carcinoma (primary liver cancer) is one of the most common malignancies worldwide with one of the highest mortality rates. Microwave ablation (MWA) is a new, promising, and multidisciplinary technology designed to destroy unhealthy tissue of various natures by radiating electromagnetic waves with microwave antennas. The finite element method (FEM) has been used in the present work to generate the simulated models of tapered cap floating sleeve antenna for validation of its design concepts, because FEM allows modeling of complex geometries that cannot be solved by analytical methods or finite difference models. The performances have been evaluated in terms of objective metrics, ablation zone, antenna matching, power absorption and SAR pattern. PMID:26115000

  18. Antipodal Linear Tapered Slot Antenna Based Radio Link Characterization in Narrow Hallway Environment at 60 GHz

    Science.gov (United States)

    Shrivastava, Purva; Rao, T. Rama

    2016-05-01

    The performance of wireless communication systems is predominantly dependent on propagation environment and respective radiating antennas. Due to the shorter wavelength at millimeter wave (MmW) frequencies, the propagation loss through the objects in indoor environments is typically very high. To improve the channel capacity and to reduce inter-user interference, a high gain directional antenna is desired at MmW frequencies. Traditional antennas used in MmW devices are not suitable for low-cost commercial devices due to their heavy and bulky configurations. This paper focuses on design and development of a very compact (44.61 × 9.93 × 0.381 mm) high gain antipodal linear tapered slot antenna (ALTSA) utilizing substrate integrated waveguide (SIW) technology at 60 GHz. Received signal strength (RSS), path loss, and capacity are studied for MmW indoor applications utilizing ALTSA with radio frequency (RF) measurement equipment in narrow hallway environment.

  19. Second-Generation Versus First-Generation Cementless Tapered Wedge Femoral Stems.

    Science.gov (United States)

    Pierce, Todd P; Jauregui, Julio J; Kapadia, Bhaveen H; Elmallah, Randa K; Cherian, Jeffrey J; Harwin, Steven F; Mont, Michael A

    2015-09-01

    Clinical outcomes of a new second-generation proximally coated, tapered wedge cementless stem were compared with those of its predecessor regarding (1) all-cause implant survivorship; (2) objective and subjective outcomes; (3) complications; and (4) radiographic features. Patients who underwent a primary total hip arthroplasty with the second-generation stem (68 hips) were compared with those who received the first-generation stem (136 hips) at a mean follow-up of 3.5 years. Although the first-generation stem was designed in the traditional manner, the second-generation stem was shortened to accommodate all surgical approaches and designed using a computed tomography scan-based database to enhance fit. The second-generation stem had survivorship, functional, and subjective outcomes similar to those of the first-generation stem. PMID:26375526

  20. Power-efficient production of photon pairs in a tapered chalcogenide microwire

    International Nuclear Information System (INIS)

    Using tapered fibers of As2Se3 chalcogenide glass, we produce photon pairs at telecommunication wavelengths with low pump powers. We found maximum coincidences-to-accidentals ratios of 2.13 ± 0.07 for degenerate pumping with 3.2 μW average power, and 1.33 ± 0.03 for non-degenerate pumping with 1.0 μW and 1.5 μW average power of the two pumps. Our results show that the ultrahigh nonlinearity in these microwires could allow single-photon pumping to produce photon pairs, enabling the production of large entangled states, heralding of single photons after lossy transmission, and photonic quantum information processing with nonlinear optics

  1. Magnetic-field sensor based on core-offset tapered optical fiber and magnetic fluid

    International Nuclear Information System (INIS)

    A magnetic field sensor based on an asymmetrical fiber modal Mach–Zehnder interferometer (MMZI) is achieved by cascading tapered fiber with the core-offset structure. The MMZI is sealed by the magnetic fluid and its spectral dependence on magnetic field has been investigated. The results show that the transmission variations of the two dips are about 8 dB and 10 dB for a magnetic intensity range from 0 Oe to 400 Oe, respectively. The highest magnetic sensitivity reaches 0.03407 dB Oe−1. The proposed sensor based on the intensity demodulation is cost-effective and robust; therefore, the device is beneficial to the magnetic field sensing applications and other magneto-optical tunable photonics devices. (paper)

  2. Microwave sidebands for laser cooling by direct modulation of a tapered amplifier

    CERN Document Server

    Mahnke, Jan; Geisel, Ilka; Jöllenbeck, Stefan; Ertmer, Wolfgang; Klempt, Carsten

    2013-01-01

    Laser cooling of atoms usually necessitates several laser frequencies. Alkaline atoms, for example, are cooled by two lasers with a frequency difference in the Gigahertz range. This gap cannot be closed with simple shifting techniques. Here, we present a method of generating sidebands at 6.6 GHz by modulating the current of a tapered amplifier which is seeded by an unmodulated master laser. The sidebands enable trapping of 1.1*10^9 Rubidium 87 atoms in a chip-based magneto-optical trap. Compared to the direct modulation of the master laser, this method allows for an easy implementation, a fast adjustment over a wide frequency range and the simultaneous extraction of unmodulated light for manipulation and detection. The low power consumption, small size and applicability for multiple frequencies benefits a wide range of applications, reaching from atom-based mobile sensors to the laser cooling of molecules.

  3. Antipodal Linear Tapered Slot Antenna Based Radio Link Characterization in Narrow Hallway Environment at 60 GHz

    Science.gov (United States)

    Shrivastava, Purva; Rao, T. Rama

    2016-09-01

    The performance of wireless communication systems is predominantly dependent on propagation environment and respective radiating antennas. Due to the shorter wavelength at millimeter wave (MmW) frequencies, the propagation loss through the objects in indoor environments is typically very high. To improve the channel capacity and to reduce inter-user interference, a high gain directional antenna is desired at MmW frequencies. Traditional antennas used in MmW devices are not suitable for low-cost commercial devices due to their heavy and bulky configurations. This paper focuses on design and development of a very compact (44.61 × 9.93 × 0.381 mm) high gain antipodal linear tapered slot antenna (ALTSA) utilizing substrate integrated waveguide (SIW) technology at 60 GHz. Received signal strength (RSS), path loss, and capacity are studied for MmW indoor applications utilizing ALTSA with radio frequency (RF) measurement equipment in narrow hallway environment.

  4. An Analytical Approach on Thermally Induced Vibrations of Nonhomogeneous Tapered Plate

    Directory of Open Access Journals (Sweden)

    Anupam Khanna

    2013-01-01

    Full Text Available A mathematical model to control the vibrations of a rectangular plate is constructed with an aim to assist engineers in designing and fabrication of various structures used in the field of science and technology, mostly used in satellite and aeronautical engineering. The present study is related to the analysis of free vibrations of nonhomogeneous rectangular plate clamped at all the four edges. Authors studied the bilinear effect of thickness as well as temperature variations in both and directions. Variation in Poisson's ratio is also considered linearly in -direction due to nonhomogeneity. Rayleigh-Ritz method is used to analyze the frequencies for the first two modes of vibrations for different values of thermal gradient, nonhomogeneity constant, taper constants and aspect ratio. All the numerical computations have been performed for an alloy of aluminum, that is, duralumin. All the results are presented in the form of graphs.

  5. Variational-method-based higher order mode analysis extendible to realistic tapered disk-loaded structures

    Science.gov (United States)

    Wang, L. F.; Lin, Y. Z.; Higo, T.

    2002-04-01

    In order to obtain high luminosity and energy efficiency in future linear colliders, most designs for e + and e - collisions in the TeV range will use multi-bunch operation. Therefore, the study of higher order modes excited by previous bunches in the train becomes very important for the optimal design of the accelerator components. Many designs have used tapered disk-loaded waveguides for acceleration. Various numerical methods have been used for the modal analysis of the structure. In this paper, a high-precision eigenmode-computation analysis based on a variational method will be discussed. It allows for rounding the edge of a disk hole without any approximation in shape treatment and calculates the exactly synchronous modes. It converges much faster than the mesh-based computer code SUPERFISH. Good agreement was observed between the results of the variational method and those of other methods.

  6. Variational-method-based higher order mode analysis extendible to realistic tapered disk-loaded structures

    CERN Document Server

    Wang, L F; Higo, T

    2002-01-01

    In order to obtain high luminosity and energy efficiency in future linear colliders, most designs for e sup + and e sup - collisions in the TeV range will use multi-bunch operation. Therefore, the study of higher order modes excited by previous bunches in the train becomes very important for the optimal design of the accelerator components. Many designs have used tapered disk-loaded waveguides for acceleration. Various numerical methods have been used for the modal analysis of the structure. In this paper, a high-precision Eigenmode-computation analysis based on a variational method will be discussed. It allows for rounding the edge of a disk hole without any approximation in shape treatment and calculates the exactly synchronous modes. It converges much faster than the mesh-based computer code SUPERFISH. Good agreement was observed between the results of the variational method and those of other methods.

  7. SPR based cone tapered fiber optic chemical sensor for the detection of low water in ethanol

    Science.gov (United States)

    Pathak, A. K.; Bhardwaj, V.; Gangwar, R. K.; Singh, V. K.

    2016-05-01

    In this paper a cone tapered surface plasmon resonance (SPR) based chemical fiber sensor is fabricated and demonstrated for the detection of low water content in ethanol. Here the 11nm thickness of Aluminum (Al) is used to coat tip of probe to generate Plasmon wave. The output power has been found to increase linearly with water content in the range 1-10% due to the increase in refractive index (RI) of ethanolabove which, as the percentage of water increases in step of 20% it shows abrupt decrease in RI hence decrease in the output power. The compact size of sensor and its low cost fabrication makes it useful for many applications in the field of chemical and biochemical sensing.

  8. Frequency-stabilized Yb:fiber comb with a tapered single-mode fiber

    Science.gov (United States)

    Yang, Xie; Hai-Nian, Han; Long, Zhang; Zi-Jiao, Yu; Zheng, Zhu; Lei, Hou; Li-Hui, Pang; Zhi-Yi, Wei

    2016-04-01

    We demonstrate a stable Yb:fiber frequency comb with supercontinuum generation by using a specially designed tapered single-mode fiber, in which a spectrum spanning from 500 nm to 1500 nm is produced. The carrier-envelope offset signal of the Yb:fiber comb is measured with a signal-to-noise ratio of more than 40 dB and a linewidth narrower than 120 kHz. The repetition rate and carrier-envelope offset signals are simultaneously phase locked to a microwave reference frequency. Project supported by the National Basic Research Program of China (973 Program) (Grant No. 2012CB821304) and the National Natural Science Foundation of China (Grant No. 61378040).

  9. Power-efficient production of photon pairs in a tapered chalcogenide microwire

    Energy Technology Data Exchange (ETDEWEB)

    Meyer-Scott, Evan, E-mail: emeyersc@uwaterloo.ca; Dot, Audrey [Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Ahmad, Raja; Li, Lizhu; Rochette, Martin [Department of Electrical and Computer Engineering, McGill University, 3480 University Street, Montréal, Québec H3A 2A7 (Canada); Jennewein, Thomas [Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada); Quantum Information Science Program, Canadian Institute for Advanced Research, 180 Dundas Street West, Suite 1400, Toronto, Ontario M5G 1Z8 (Canada)

    2015-02-23

    Using tapered fibers of As{sub 2}Se{sub 3} chalcogenide glass, we produce photon pairs at telecommunication wavelengths with low pump powers. We found maximum coincidences-to-accidentals ratios of 2.13 ± 0.07 for degenerate pumping with 3.2 μW average power, and 1.33 ± 0.03 for non-degenerate pumping with 1.0 μW and 1.5 μW average power of the two pumps. Our results show that the ultrahigh nonlinearity in these microwires could allow single-photon pumping to produce photon pairs, enabling the production of large entangled states, heralding of single photons after lossy transmission, and photonic quantum information processing with nonlinear optics.

  10. U-shaped, double-tapered, fiber-optic sensor for effective biofilm growth monitoring.

    Science.gov (United States)

    Zhong, Nianbing; Zhao, Mingfu; Li, Yishan

    2016-02-01

    To monitor biofilm growth on polydimethylsiloxane in a photobioreactor effectively, the biofilm cells and liquids were separated and measured using a sensor with two U-shaped, double-tapered, fiber-optic probes (Sen. and Ref. probes). The probes' Au-coated hemispherical tips enabled double-pass evanescent field absorption. The Sen. probe sensed the cells and liquids inside the biofilm. The polyimide-silica hybrid-film-coated Ref. probe separated the liquids from the biofilm cells and analyzed the liquid concentration. The biofilm structure and active biomass were also examined to confirm the effectiveness of the measurement using a simulation model. The sensor was found to effectively respond to the biofilm growth in the adsorption through exponential phases at thicknesses of 0-536 μm. PMID:26977344

  11. Biodegradation kinetics during different start up of the anaerobic tapered fluidized bed reactor

    Directory of Open Access Journals (Sweden)

    Rangasamy Parthiban

    2011-10-01

    Full Text Available Kinetic study for different start up conditions of the anaerobic digestion of wastewater derived from the sago processingfrom tubers of tapioca (Mannihot utillisema is discussed. The experiment is carried out with synthetic waste water usinga tapered fluidized bed reactor. Mesoporous granulated activated carbon is used as a bacterial support. The kinetic modelfollows half order kinetics for substrate utilization and for methane formation and it exhibits an order of 0.20 during thestart up of the reactor without acclimatization. For the remaining start up with acclimatized sludge, kinetic parameters areexpressed in terms of Langmuir-Hinshelwood kinetics for the substrate utilization. The methane formation kinetics followsan order of the reaction as 0.30. The values of the kinetic constants are in the range of 0.13–0.21.

  12. Effect of Taper on Stress Distribution of All Ceramic Fixed Partial Dentures: a 3D-FEA Study

    Directory of Open Access Journals (Sweden)

    F. Gerami-Panah

    2005-09-01

    Full Text Available Statement of Problem: Mechanical failure of ceramic materials is controlled by brittle fracture, mostly occurred in tension. In 3-unit all-ceramic FPDs the connector area is considered to be at fracture risk because of tensile stress concentrations.Purpose: The aim of this FE analysis was to evaluate the effect of taper on stress distribution in all-ceramic FPDs.Materials and Methods: In this experimental study two 3-D finite element models of thee-unit IPS-Empress 2 FPDs replacing mandible second premolar were created by means of finite element software. The digital images were obtained from CT scan of human skull. Abutment was reduced with 12 and 22 degrees of taper. The cement layer,PDL, cancellous bone and cortical bone were also modeled. Frameworks of core material were fabricated. A static load of 100 N was applied at mid pontic area.Resolved stresses were calculated according to the Von Mises criterion and principal stresses.Results: In both models stresses were concentrated at the connectors. The maximum stresses were lower in the model with larger taper. The maximum Von Mises stress was recorded at the connector region of the premolar and the pontic. In model with larger taper the patterns of stresses were also more distributed and less concentrated.Conclusion: The highest Von Mises and principal stress were recorded at the connectors. Tensile stresses developed at the gingival connector of premolar and pontic was higher than molar. The stress level in model with 22-degree taper was lower compare to 12-degree and the stress pattern was more distributed, lowered the risk ofconcentrations.

  13. High-power high-brightness tapered lasers with an Al-free active region at 915 nm

    Science.gov (United States)

    Michel, N.; Hassiaoui, I.; Lecomte, M.; Parillaud, O.; Calligaro, M.; Krakowski, M.

    2006-02-01

    We have developed high power and high brightness tapered lasers based on an Al-free active region at 915 nm. The material structure, which was grown by MOCVD (Metallorganic Chemical Vapor Deposition), has very low internal losses of 0.5 cm -1, a very low transparency current density of 86 A/cm2, a high internal quantum efficiency of 86%, and a high characteristic temperature T 0 of 171 K. Based on these good results, we have realised index-guided tapered lasers (IG1) with a narrow output width of a few tens of microns, a narrow taper angle of less than 1 °, which deliver 1 W CW, together with an M2 beam quality parameter of 3.0, and a divergence angle in the slow axis of 6 ° FWHM and 10.2 ° at 1/e2. We have also realised a small array of six IG1 lasers, which delivers 4 W CW, together with a divergence angle of 5.6 ° FWHM and 10.2 ° at 1/e2. Clarinet lasers were also fabricated. These devices were recently proposed to achieve high brightness together with a very narrow divergence angle, which is stable with current. These index-guided tapered lasers have also a narrow output width, but a larger taper angle of 2 °. The Clarinet lasers at 915 nm deliver 0.65 W CW, together with an M2 beam quality factor of less than 1.5 at 1/e2, and a very narrow divergence angle of 2.6 ° FWHM, and 4.8 ° at 1/e2.

  14. Aplanatic beam shaping for diffraction limited beam circularization of tapered laser diodes

    Science.gov (United States)

    Heinrich, Arne; Hagen, Clemens; Harlander, Maximilian; Nussbaumer, Bernhard

    2014-03-01

    Many laser applications require a circular, astigmatism-free, diffraction limited, high power beam. A tapered laser diode can generate up to 6 W output power in a diffraction limited beam. However the beam is elliptical and highly astigmatic rendering the design of beam shaping challenging. We present a diffraction limited beam shaping design, especially suitable to circularize and collimate highly astigmatic beams. The setup consists of a simple plano-convex cylindrical lens in the aplanatic condition and an asphere. The first lens matches the divergence of the fast- to the slow axis at the point where the beam is circular while the following asphere collimates the beam. The aplanatic condition is fulfilled by choosing a glass with a specific refractive index depending on the ratio between fast- and slow axis divergence. This cylindrical lens introduces neither spherical error nor primary coma, which makes it insensitive to misalignment. The setup has been tested with a high power laser diode at 980 nm with a 6 mm long taper (angle 6°) and a facet width of 425 μm. The optics have a transmission of about 90% and the resulting beam has a M2 < 1.5. As a proof of principle 3.2 W were coupled into a 15 μm (NA 0.06) LMA fiber with 55% efficiency corresponding to a brightness B = 140 MW/(cm2 sr). Furthermore the presented beam shaping can easily be extended to bars or multiple emitters to reach power levels that are to date only achievable with complex wavelength combination techniques.

  15. Discontinuation symptoms and taper/poststudy-emergent adverse events with desvenlafaxine treatment for major depressive disorder.

    Science.gov (United States)

    Montgomery, Stuart A; Fava, Maurizio; Padmanabhan, Sudharshan K; Guico-Pabia, Christine J; Tourian, Karen A

    2009-11-01

    The objective of this study was to assess discontinuation symptoms with desvenlafaxine (administered as desvenlafaxine succinate) treatment for major depressive disorder. Data were analyzed from nine 8-week, double-blind (DB), placebo-controlled studies of desvenlafaxine (50, 100, 200, or 400 mg/day; placebo, n = 319; desvenlafaxine, n = 578) and a relapse-prevention study [12-week, open-label (OL) 200 or 400 mg/day desvenlafaxine (n = 373); 6-month DB placebo (n = 73) or desvenlafaxine (n = 118)]. Rates of taper/poststudy-emergent adverse events were summarized. Discontinuation-Emergent Signs and Symptoms (DESS) checklist scores were analyzed in treatment completers at the end of OL and DB treatment. The most common (> or = 5%) taper/poststudy-emergent adverse events among desvenlafaxine patients were dizziness, nausea, headache, irritability, diarrhea, anxiety, abnormal dreams, fatigue, and hyperhidrosis. In the short-term studies, the highest DESS scores observed for desvenlafaxine groups occurred at first assessment after discontinuation of all active treatment (1.9-5.7). Desvenlafaxine 50- and 100-mg/day groups had significantly increased scores versus placebo (P values < or = 0.028). DESS scores increased significantly for patients discontinuing 12-week, OL desvenlafaxine 200 and 400 mg/day doses compared with those continuing desvenlafaxine (P values < or = 0.022). After the 6-month DB phase, DESS scores increased significantly compared with placebo for patients discontinuing 400 mg/day only (P = 0.029). In conclusion, cessation of desvenlafaxine use is associated with discontinuation symptoms after both short-term and long-term treatment. PMID:19779354

  16. Signifying Bodies

    DEFF Research Database (Denmark)

     In our everyday lives we strive to stay healthy and happy, while we live as our selves, engage with each other, and discover an infinite world of possibilities. Health arises and diminishes as human beings draw on a vibrant ecology of actions, interactions and coactions. Intricate processes of...... biosemiosis connect signifying bodies with their natural surroundings, cultural activities and subjective experiences. Health stretches all the way from the ecosocial surroundings, through the skin and into the self-organizing processes of every living cell. Signifying Bodies lays out a new approach to health...... and health care. Eschewing all forms of dualism, the authors emphasise the interdependency of how we act, think, feel and function. They advocate a relational turn in health care, in which bodies live and learn from suffering and care. In this view, health is inseparable from both living beings and...

  17. Body Imaging

    Science.gov (United States)

    2001-01-01

    The high-tech art of digital signal processing (DSP) was pioneered at NASA's Jet Propulsion Laboratory (JPL) in the mid-1960s for use in the Apollo Lunar Landing Program. Designed to computer enhance pictures of the Moon, this technology became the basis for the Landsat Earth resources satellites and subsequently has been incorporated into a broad range of Earthbound medical and diagnostic tools. DSP is employed in advanced body imaging techniques including Computer-Aided Tomography, also known as CT and CATScan, and Magnetic Resonance Imaging (MRI). CT images are collected by irradiating a thin slice of the body with a fan-shaped x-ray beam from a number of directions around the body's perimeter. A tomographic (slice-like) picture is reconstructed from these multiple views by a computer. MRI employs a magnetic field and radio waves, rather than x-rays, to create images.

  18. Body Rainbow

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    Phubu did not know how long hehad walked after leaving Baxoi, buthe did know that he was halfwaybetween home and Lhasa. Feelingthe weight of the sack containingPhumo's body on his back, Fhubuhad calmed down from the grief anddesperation. He had just one wish:to carry Phumo to Lhasa. He knewthat Phumo had gone, and her soulwas no longer in this body. But hewas determined to finish the trip, notonly because he had promised so, butalso that he believed that it would beredemption for him.

  19. Sacralising Bodies

    DEFF Research Database (Denmark)

    Kaur, Ravinder

    2010-01-01

    sacralisation is realised through co-production within a social setting when the object of sacralisation is recognised as such by others. In contemporary Iran, however, the moment of sacralising bodies by the state is also the moment of its own subversion as the political-theological field of martyrdom is......-sacrifice became central to the mass mobilisation against the monarchy. Once the revolutionary government came into existence, this sacred tradition was regulated to create ‘martyrs’ as a fixed category, in order to consolidate the legacy of the revolution. In this political theatre, the dead body is a site of...

  20. Novel ultra-broadband polarization splitter-rotator based on mode-evolution tapers and a mode-sorting asymmetric Y-junction

    OpenAIRE

    Jing WANG; Niu, Ben; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Qi, Minghao; Gan, Fuwan

    2014-01-01

    A novel silicon-on-insulator (SOI) polarization splitter-rotator is proposed based on mode-evolution tapers and a mode-sorting asymmetric Y-junction. The tapers are designed to adiabatically convert the input TM0 mode into the TE1 mode, which will evolve into the TE0 mode in the wide output arm while the input TE0 mode excites the TE0 mode in the narrow arm. The numerical simulation results show that the mode conversion efficiency increases with the lengths of the tapers and the Y-junction fo...

  1. Experimental Investigation of Subject-Specific On-Body Radio Propagation Channels for Body-Centric Wireless Communications

    Directory of Open Access Journals (Sweden)

    Mohammad Monirujjaman Khan

    2014-01-01

    Full Text Available In this paper, subject-specific narrowband (2.45 GHz and ultra-wideband (3–10.6 GHz on-body radio propagation studies in wireless body area networks (WBANs were performed by characterizing the path loss for eight different human subjects of different shapes and sizes. The body shapes and sizes of the test subjects used in this study are characterised as thin, medium build, fatty, shorter, average height and taller. Experimental investigation was made in an indoor environment using a pair of printed monopoles (for the narrowband case and a pair of tapered slot antennas (for the ultra-wideband (UWB case. Results demonstrated that, due to the different sizes, heights and shapes of the test subjects, the path loss exponent value varies up to maximum of 0.85 for the narrowband on-body case, whereas a maximum variation of the path loss exponent value of 1.15 is noticed for the UWB case. In addition, the subject-specific behaviour of the on-body radio propagation channels was compared between narrowband and UWB systems, and it was deduced that the on-body radio channels are subject-specific for both narrowband and UWB system cases, when the same antennas (same characteristics are used. The effect of the human body shape and size variations on the eight different on-body radio channels is also studied for both the narrowband and UWB cases.

  2. Multiwavelength mode-locked erbium-doped fiber laser based on the interaction of graphene and fiber-taper evanescent field

    International Nuclear Information System (INIS)

    We report on the generation of multiwavelength passively mode-locked pulses in an erbium-doped fiber laser (EDFL) based on the interaction of graphene and fiber-taper evanescent field. Graphene-polymer nanocomposites in aqueous suspension are trapped by the optical evanescent light and deposited on taper region. The graphene-deposited fiber-taper device not only acts as an excellent saturable absorber for mode-locking, but also induces a polarizing effect to form an artificial birefringent filter for multiwavelength selection. By simultaneously exploiting both functions of this device, four-wavelength continuous-wave mode-locking operation of an EDFL is stably initiated with a pulse width of 8.8 ps and a fundamental repetition rate of 8.034 MHz. This is the first time, to our knowledge, the mode-locked EDFL using such a new geometry of graphene-based tapered-fiber saturable absorber has been demonstrated

  3. Effect of Abutment Taper on the Fracture Resistance of all-Ceramic Three-unit Bridges

    Directory of Open Access Journals (Sweden)

    F. Gerami-Panah

    2005-12-01

    Full Text Available Statement of Problem: The connector area is the weakest zone of an all-ceramic fixed partial denture (FPD, where most catastrophic failures of the prostheses tend to occur.Purpose: The aim of the present study was to assess the effect of the convergence angle of abutments on the fracture resistance of three-unit fixed partial dentures made of IPSEmpress2.Materials and Methods: Forty extracted human premolars and molars were used to reproduce twenty, 3-unit fixed partial dentures, for the replacement of second premolars. All teeth were prepared according to the guidelines outlined for all-ceramic crowns and bridges, except for the convergence angles of the abutments. The specimens were randomly divided into two groups of 10, with total occlusal convergence angles of 12° and 22°. Fixed partial dentures with a uniform thickness of 0.8 mm were fabricated using IPS-Empress2 and were bonded to the corresponding models. Connectordimensions were set to 4 mm height and 4mm width. The radius of curvature at the gingival embrasure was carved to 0.9 mm. All specimens were exposed to 10,000 preloading cycles and a load of 40 N at a frequency of 1.3 Hz in a standardized testing machine at a cross head speed of 1mm/min. Student t-test was performed to detect any difference in the mean fracture resistance between the two groups (α = 0.05.Results: Mean failure loads (and standard deviations of the 12° and 22° groups were 1009.12 N (208.05 and 1182.72 N (144.67, respectively. Statistical analysis revealed a significant difference (P <0.04 between the mean failure loads of the two groups. Mostfractures occurred through the connectors.Conclusion: The mean failure loads of the investigated fixed partial dentures were higher in the abutments with 22° taper as compared to those with a taper of 12°.

  4. Fatigue and Damage Tolerance Analysis of a Hybrid Composite Tapered Flexbeam

    Science.gov (United States)

    Murri, Gretchen B.; Schaff, Jeffrey R.; Dobyns, Al

    2001-01-01

    The behavior of nonlinear tapered composite flexbeams under combined axial tension and cyclic bending loading was studied using coupon test specimens and finite element (FE) analyses. The flexbeams used a hybrid material system of graphite/epoxy and glass/epoxy and had internal dropped plies, dropped in an overlapping stepwise pattern. Two material configurations, differing only in the use of glass or graphite plies in the continuous plies near the midplane, were studied. Test specimens were cut from a full-size helicopter tail-rotor flexbeam and were tested in a hydraulic load frame under combined constant axialtension load and transverse cyclic bending loads. The first determination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group in the tapered region of the flexbeam, near the thick end. Delaminations grew slowly and stably, toward the thick end of the flexbeam, at the interfaces above and below the dropped-ply region. A 2D finite element model of the flexbeam was developed. The model was analyzed using a geometrically non-linear analysis with both the ANSYS and ABAQUS FE codes. The global responses of each analysis agreed well with the test results. The ANSYS model was used to calculate strain energy release rates (G) for delaminations initiating at two different ply-ending locations. The results showed that delaminations were more inclined to grow at the locations where they were observed in the test specimens. Both ANSYS and ABAQUS were used to calculate G values associated with delamination initiating at the observed location but growing in different interfaces, either above or below the ply-ending group toward the thick end, or toward the thin end from the tip of the resin pocket. The different analysis codes generated the same trends and comparable peak values, within 5-11 % for each delamination path. Both codes showed that delamination toward the thick region was largely mode II, and toward the thin

  5. Quantifying the effects of material properties on analog models of critical taper wedges

    Science.gov (United States)

    Hofmann, F.; Rosenau, M.; Schreurs, G.; Friedrich, A. M.

    2012-04-01

    Analogue models are inherently handmade and reflect their creator's shaping character. For example, sieving style in combination with grain geometry and distribution have been claimed to influence bulk material properties and the outcome of analogue experiments. Few studies exist that quantify these effects and here we aim at investigating the impact of bulk properties of granular materials on the structural development of convergent brittle wedges in analogue experiments. In a systematic fashion, natural sands as well as glass beads of different grain size and size distribution were sieved by different persons from different heights and the resulting bulk density was measured. A series of analogue experiments in both the push and pull setup were performed. The differences in the outcome of experiments were analyzed based on sidewall pictures and 3D laserscanning of the surface. A new high-resolution approach to measuring surface slope automatically is introduced and applied to the evaluation of images and profiles. This procedure is compared to manual methods of determining surface slope. The effect of sidewall friction was quantified by measuring lateral changes in surface slope. The resulting dataset is used to identify the main differences between pushed and pulled wedge experiments in the light of critical taper theory. The bulk density of granular material was found to be highly dependent on sieve height. Sieve heights of less than 50 cm produced a bulk density that was up to 10% less than the maximum bulk density; an effect equally shown for different people sieving the material. Glass beads were found to produce a more regular structure of in-sequence-thrusts in both, space and time, than sands while displaying less variability. Surface slope was found to be highly transient for pushed wedge experiments, whereas it reached and attained a stable value in pulled experiments. Pushed wedges are inferred to develop into a supercritical state because they exceed

  6. Tunable and switchable dual-wavelength erbium-doped fiber laser based on in-line tapered fiber filters

    Science.gov (United States)

    Tong, Zheng-rong; Yang, He; Cao, Ye

    2016-07-01

    A tunable and switchable dual-wavelength erbium-doped fiber laser (EDFL) based on all-fiber single-mode tapered fiber structure has been demonstrated. By adjusting the variable optical attenuator (VOA), the laser can be switched between the single-wavelength mode and the dual-wavelength mode. When the temperature applied on the tapered fiber structure varies, the pass-band varies and the wavelength of the output laser shifts correspondingly. When the temperature changes from 30 °C to 180 °C, the central wavelength of the EDFL generated by branch A shifts from 1 550.7 nm to 1 560.3 nm, while that of branch B shifts from 1 530.8 nm to 1 540.4 nm, indicating the wavelength interval is tunable. These advantages enable this laser to be a potential candidate for high-capacity wavelength division multiplexing systems and mechanical sensors.

  7. Ultrahigh Resolution Spectroscopy Across the Visible to Infrared Spectrum Using Multi-Mode Interference in a Compact Tapered Fiber

    CERN Document Server

    Wan, Noel H; Shiue, Ren-Jye; Chen, Edward H; Schröder, Tim; Englund, Dirk

    2014-01-01

    Optical spectroscopy is a fundamental tool in numerous areas of science and technology. Much effort has focused on miniaturizing spectrometers, but thus far at the cost of high spectral resolution and broad operating range. Here, we describe a compact spectrometer without this trade-off. The device relies on imaging multi-mode interference from leaky modes along a highly multimode tapered optical fiber, resulting in spectrally distinguishable images that form a basis for reconstructing an incident light spectrum. This tapered fiber multimode interference spectrometer enables the acquisition of broadband spectra in a single camera exposure with a measured resolution of 40 pm in the visible spectrum and 10 pm in the infrared spectrum, which are comparable to the performance of grating spectrometers. Spectroscopy from 500 nm to 1600 nm is demonstrated, though operation across the entire transparency window of silica fibers is possible. Multimode interference spectroscopy of leaky modes is suitable in a variety o...

  8. Wavelength Spacing Tunable, Multiwavelength Q-Switched Mode-Locked Laser Based on Graphene-Oxide-Deposited Tapered Fiber

    CERN Document Server

    Gao, Lei; Zeng, Jing

    2014-01-01

    A wavelength spacing tunable, multiwavelength Q-switched mode-locked (QML) fiber laser in an erbium-doped fiber cavity based on graphene oxide deposited on tapered fiber is proposed by choosing the diameter and length of the taper, graphene oxide thickness and cavity dispersion, in which the wavelength spacing could be tuned by pump power. The evolutions of temporal and spectral with different pump strengths are investigated. Results show that the tunability of the multiwavelength laser can be interpreted by the bound states of QML laser resulting from a mutual interaction of dispersion, nonlinear effect, insertion loss, and pump power. To the best of our knowledge, it is the first experimental observation of bound states of QML, which provides a new mechanism to fabricate tunable multiwavelength laser.

  9. Effective Synthesis and Recovery of Silver Nanowires Prepared by Tapered Continuous Flow Reactor for Flexible and Transparent Conducting Electrode

    Directory of Open Access Journals (Sweden)

    Hyung Duk Yun

    2016-01-01

    Full Text Available Silver nanowires (AgNWs with high aspect ratio were obtained utilizing a tapered tubular reactor by the polyol process. The tapered tubular type flow reactor allowed us to obtain nanowires in high yield without defects that is generally encountered in a closed reactor due to excessive shearing for a long time. After reaction the AgNWs were precipitated in the aqueous solution with the aid of a hydrogen bond breaker and were recovered effectively without using a high-cost centrifugation process. Dispersion of the AgNWs were used to prepare transparent conducting electrode (TCE films by a spray coating method, which showed 86% transmittance and 90 Ωsq−1 sheet resistance.

  10. Measurement of out-of plane displacement of a tapered canti-lever using Twymann-Green Interferometry

    International Nuclear Information System (INIS)

    The Twymann-Green interferometry is applied to measure surface deformations of mechanical components in industrial areas with non-contact since it requires relatively simple optical arrangement. In this study, a tapered canti-lever beam was used to measure out-of-plane displacement by Twymann-Green interferometry. The surface of the specimen was polished to be shown as that of a mirror. Fringes observed from the specimen with a shiny surface include speckle noise and are similar to those obtained from the specimen sprayed by white paint. Gussian blur which is a commercial software is used to eliminate high frequency speckle noise. Phase shifted four fringes using PZT were captured and were used to calculated phased image. Experimental results of the tapered canti-levered plate analyzed by 4-step phase shifting method are close to the theoretical expectation.

  11. Investigation of Nucleation Mechanism and Tapering Observed in ZnO Nanowire Growth by Carbothermal Reduction Technique

    Directory of Open Access Journals (Sweden)

    Oye Michael

    2011-01-01

    Full Text Available Abstract ZnO nanowire nucleation mechanism and initial stages of nanowire growth using the carbothermal reduction technique are studied confirming the involvement of the catalyst at the tip in the growth process. Role of the Au catalyst is further confirmed when the tapering observed in the nanowires can be explained by the change in the shape of the catalyst causing a variation of the contact area at the liquid–solid interface of the nanowires. The rate of decrease in nanowire diameter with length on the average is found to be 0.36 nm/s and this rate is larger near the base. Variation in the ZnO nanowire diameter with length is further explained on the basis of the rate at which Zn atoms are supplied as well as the droplet stability at the high flow rates and temperature. Further, saw-tooth faceting is noticed in tapered nanowires, and the formation is analyzed crystallographically.

  12. A high-average power tapered FEL amplifier at submillimeter frequencies using sheet electron beams and short-period wigglers

    International Nuclear Information System (INIS)

    A high-average-power FEL amplifier operating at submillimeter frequencies is under development at the University of Maryland. Program goals are to produce a CW, ∼1 MW, FEL amplifier source at frequencies between 280 GHz and 560 GHz. To this end, a high-gain, high-efficiency, tapered FEL amplifier using a sheet electron beam and a short-period (superconducting) wiggler has been chosen. Development of this amplifier is progressing in three stages: (1) beam propagation through a long length (∼1 m) of short period (λω = 1 cm) wiggler, (2) demonstration of a proof-of-principle amplifier experiment at 98 GHz, and (3) designs of a superconducting tapered FEL amplifier meeting the ultimate design goal specifications. 17 refs., 1 fig., 1 tab

  13. Tapered large-core 976 nm Yb-doped fiber laser with 10 W output power

    International Nuclear Information System (INIS)

    We report on a tapered large-core Yb fiber laser operating at 976 nm emission wavelength. It was realized using a high-numerical aperture large-core fiber with 126 μm core diameter, which was fabricated by powder-sinter technology and shows a very homogeneous step-index profile. The end of the fiber is tapered down to match a single-mode fiber containing a fiber Bragg grating. Using the benefits of core-pumping and the feedback of the spliced fiber Bragg grating, we achieved efficient pump light absorption and wavelength stable 976 nm lasing with single-mode performance. We could demonstrate 10 W laser power out of a 10 μm fiber core with a slope efficiency of 31% with respect to the launched pump power. The presented device is well-suited for fiber-coupled pumping of amplifiers for high peak power. (letter)

  14. Coupling of ultrathin tapered fibers with high-Q microsphere resonators at cryogenic temperatures and observation of phase-shift transition from undercoupling to overcoupling

    CERN Document Server

    Fujiwara, Masazumi; Tanaka, Akira; Toubaru, Kiyota; Zhao, Hong-Quan; Takeuchi, Shigeki; 10.1364/OE.20.019545

    2012-01-01

    We cooled ultrathin tapered fibers to cryogenic temperatures and controllably coupled them with high-Q microsphere resonators at a wavelength close to the optical transition of diamond nitrogen vacancy centers. The 310-nm-diameter tapered fibers were stably nanopositioned close to the microspheres with a positioning stability of approximately 10 nm over a temperature range of 7-28 K. A cavity-induced phase shift was observed in this temperature range, demonstrating a discrete transition from undercoupling to overcoupling.

  15. Body contact and body language

    DEFF Research Database (Denmark)

    Winther, Helle Dagmar

    2008-01-01

    and the boundaries between self and world. In western societies, the modern premises for contact are in some ways developing from close contact to virtual communication. With this breadth of perspective in mind, the ques­tion is whether conscious and experimental work with body contact and body language in move......­ment psychology and education provide potential for intense personal develop­ment as well as for social and cultural learning processes. This performative research project originates from the research project entitled, Movement Psy­chol­ogy: The Language of the Body and the Psy­chol­ogy of Movement based...... on the Dance Therapy Form Dansergia. The author, who is a practi­tioner-researcher, is methodologically inspir­ed by phenomenology, performative methods and a narrative and auto-ethnographic approach. The project will be presented in an organic, cre­at­ive and performative way. Through a moving dia...

  16. Probing of ultrahigh optical Q-factors of individual liquid microdroplets on superhydrophobic surfaces using tapered optical fiber waveguides

    OpenAIRE

    Jonas, Alexandr; Karadağ, Yasin ; Kiraz, Alper; Mestre, Michael

    2012-01-01

    We report measurements of ultrahigh quality factors (Q-factors) of the optical whispering-gallery modes excited via a tapered optical-fiber waveguide in single glycerol-water microdroplets standing on a superhydrophobic surface in air. Owing to the high contact angle of the glycerol-water mixture on the superhydrophobic surface (>155 degrees), microdroplets with the geometry of a truncated sphere minimally distorted by gravity and contact line pinning effects could be generated. Q-factors up ...

  17. Simulation of the Second Grade Fluid Model for Blood Flow through a Tapered Artery with a Stenosis

    International Nuclear Information System (INIS)

    We analyze the blood flow through a tapered artery, assuming the blood to be a second order fluid model. The resulting nonlinear implicit system of partial differential equations is solved by the perturbation method. The expressions for shear stress, velocity, flow rate, wall shear stress and longitudinal impedance are obtained. The physical behavior of different parameters is also discussed, as are trapping phenomena. (cross-disciplinary physics and related areas of science and technology)

  18. Evaluation of a portable nephelometer against the Tapered Element Oscillating Microbalance method for monitoring PM2.5

    OpenAIRE

    KARAGULIAN FEDERICO; BELIS CLAUDIO; LAGLER Friedrich; BARBIERE MAURIZIO; GERBOLES Michel

    2011-01-01

    Monitoring personal exposure to particle matter (PM2.5) in ambient air requires performing measurements using portable monitors. In this work, the portable nephelometer SidePak AM510 Personal Aerosol Monitor manufactured by TSI Inc. was evaluated against a Tapered Element Oscillating Microbalance (TEOM) equipped with a Filter Dynamics Measurements System (FDMS). Conventionally, the SidePak is calibrated with respect to the Arizona Road Test Dust and then multiplied by an environmental calibra...

  19. Combined effect of end-rounded versus tapered bristles and a dentifrice on plaque removal and gingival abrasion.

    Science.gov (United States)

    Caporossi, Leonardo Stephan; Dutra, Danilo Antonio Milbradt; Martins, Maritieli Righi; Prochnow, Emilia Pithan; Moreira, Carlos Heitor Cunha; Kantorski, Karla Zanini

    2016-01-01

    Two previous clinical studies evaluated the effect of end-rounded versus tapered bristles of soft manual brushes on the removal of plaque and gingival abrasion. However, the combined effect of an abrasive dentifrice on these outcomes has yet to be understood. The purpose of the present study was to compare the incidence of gingival abrasion and the degree of plaque removal obtained after the use of toothbrushes with tapered or end-rounded bristles in the presence or absence of an abrasive dentifrice. The study involved a randomized, single-blind, crossover model (n = 39) with a split-mouth design. Subjects were instructed to refrain from performing oral hygiene procedures for 72 hours. Quadrants were randomized and subjects brushed with both types of toothbrushes using a dentifrice (relative dentin abrasion = ± 160). Plaque and gingival abrasion were assessed before and after brushing. After 7 days, the experiment was repeated without the dentifrice. The average reduction in plaque scores and the average increase in the number of abrasion sites were assessed by repeated-measures ANOVA and Bonferroni's post-hoc tests. End-rounded bristles removed significantly more plaque than tapered bristles, regardless of the use of a dentifrice. The dentifrice did not improve plaque removal. In the marginal area (cervical free gingiva), no difference in the incidence of gingival abrasion was detected between toothbrush types when used with a dentifrice (p ≥ 0.05). However, the dentifrice increased the incidence of abrasion (p causing a higher incidence of gingival abrasion when compared with tapered bristles. An abrasive dentifrice can increase the incidence of abrasion, and should be used with caution by individuals who are at risk of developing gingival recession. PMID:26981758

  20. Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses

    OpenAIRE

    Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin; Park, Ji-Man

    2013-01-01

    PURPOSE The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment comple...

  1. [Retention of crowns as affected by film thickness of zinc phosphate cement and taper angle of crowns (author's transl)].

    Science.gov (United States)

    Otani, H; Goto, T

    1979-10-01

    Dependence of the retention of crowns at their axial wall on the film thickness of zinc phosphate cement and the taper angle was investigated. Stainless steel dies, composed of a preparation and an occlusally perforated crown the taper angle of which was 2.9, 5.7, 8.5 and 11.3 degrees respectively (Fig. 1, (a) and (b)), were cemented within three min. after the start of mix with a Shofu Micro Cement having a powder-liquid ratio of 1.5 g/0.5 cc. The thickness of the cement layer at the axial wall was regulated to a given value between 9 and 55 mu through the use of a discrepancy measurer. A Shimazu Autograph tensile test machine was employed to measure 48-hr retention (kg/cm2). The retention of the crowns was strongly dependent on the cement film thickness and the taper angle when the film thickness was below a critical value (15 mu in this experiment), but not when the film thickness was above this value (Fig. 3). This may be explained by the term of mechanical interlocking of either of the unreacted powder grains and the matrix phase in the luting cement, as schematically drawn in Fig. 6. The same findings were more evidently appeared on the semilogarythmic diagram in Fig. 4. In this diagram, the critical value was shown as intersection of two straight lines which could be drawn through all the measurements for four taper angles, using the least squares. PMID:295065

  2. Influence of the confinement factor on the wavelength-dependent output properties of a tapered traveling-wave semiconductor amplifier

    OpenAIRE

    Gahl, A.; Balle, Salvador

    1999-01-01

    We analyze the influence of the confinement factor on the output properties of a tapered traveling-wave semiconductor amplifier as a function of the wavelength of the input field and current injected into the amplifier. The interaction of the optical field with the amplifying medium is described by means of a susceptibility function taking into account both the gain and the carrier-induced antiguiding effect, while the beam propagation method is used to describe the evolution of the field alo...

  3. The effect of electropolishing on torque and force during simulated root canal preparation with ProTaper shaping files

    OpenAIRE

    Boessler, C; Paqué, F; Peters, O A

    2009-01-01

    Surface modifications of nickel-titanium instruments such as electropolishing may reduce fracture incidence but could potentially alter the instruments' mechanical properties. We studied the impact of two surface types, machined and electropolished, of ProTaper shaping files on torque and force during simulated root canal preparation. Pilot holes of 0.5-mm diameter were drilled perpendicularly through 3-mm thick human dentin discs and served as standardized simulated root canals (SSRCs). A to...

  4. Statistical properties of the radiation from SASE FEL operating in a post-saturation regime with and without undulator tapering

    CERN Document Server

    Schneidmiller, E A

    2015-01-01

    We describe statistical and coherence properties of the radiation from x-ray free electron lasers (XFEL) operating in the post-saturation regime. We consider practical case of the SASE3 FEL at the European XFEL. We perform comparison of the main characteristics of the X-ray FEL operating in the post-saturation regime with and without undulator tapering: efficiency, coherence time and degree of transverse coherence.

  5. A Tapered Chalcogenide Microstructured Optical Fiber for Mid-IR Parabolic Pulse Generation: Design and Performance Study

    OpenAIRE

    Barh, Ajanta; Ghosh, S.; Varshney, Ravi K.; Pal, Bishnu P.

    2013-01-01

    This paper presents a theoretical design of chalcogenide glass based tapered microstructured optical fiber (MOF) to generate high power parabolic pulses (PPs) at the mid-IR wavelength (~ 2 {\\mu}m). We optimize fiber cross-section by the multipole method and studied pulse evolution by well known Symmetrized Split-Step Fourier Method. Our numerical investigation reveals the possibility of highly efficient PP generation within a very short length (~ 18 cm) of this MOF for a Gaussian input pulse ...

  6. Robust design of an optical router based on a tapered side-coupled integrated spaced sequence of optical resonators.

    Science.gov (United States)

    Bettotti, P; Mancinelli, M; Guider, R; Masi, M; Vanacharla, M Rao; Pavesi, L

    2011-04-15

    A novel (to our knowledge) scheme of an optical router/switch element, composed of a tapered side-coupled integrated spaced sequence of optical resonators, is proposed. It is based on a modified design of the ring sequence in which the resonance conditions are set by the single ring resonance and by the coherent feedback of the sequence of rings. This double condition yields robustness against fabrication defects, dense routing capability, and high switching efficiency. PMID:21499394

  7. Body counter

    International Nuclear Information System (INIS)

    The paper gives a survey on some applications of the whole body counter in clinical practice and a critical study of its application as a routine testing method. Remarks on the necessary precautions are followed by a more detailed discussion of the determination of the natural potassium content, the iron metabolism, the vitamin B12 test, investigations of the metabolism of the bone using 47Ca and 85Sr, investigations with iodine and iodine-labelled substances, clearance investigations (in particular the 51Cr EDTA clearance test), as well as the possibilities of neutron activation in vivo. (ORU/AK)

  8. Theoretical study of mode evolution properties in a 3×1 adiabatic tapered single-mode fiber combiner

    Science.gov (United States)

    Zhou, Xuanfeng; Chen, Zilun; Zhou, Hang; Hou, Jing

    2015-02-01

    We study the mode evolution properties in a 3 x 1 adiabatic tapered single-mode fiber combiner (ATSMFC) in theory. The fabrication of the combiner for single mode fibers based on adiabatic tapered fused bundle (TFB) technique with the assistant of low index glass capillary is introduced. The whole taper region can be seen as three phase: single-mode fibers, multi-core fiber and multi-mode fiber. Supermodes of three-core fiber with scalar mode results are derived based on coupling mode theory. The analysis is verified with numerical examples by fully vectorial finite element mode solver (Cosmol Multiphysics). Simulation results show that the three input core modes in single-mode fibers gradually evolve into three supermodes in three-core fiber and then evolve into three low-order modes in the multi-core fiber. Effective indices for different modes are calculated which can depict the evolution process vividly. The results may be useful for practical high power fiber laser systems.

  9. Acrylic and metal based Y-branch plastic optical fiber splitter with optical NOA63 polymer waveguide taper region

    Science.gov (United States)

    Ehsan, Abang Annuar; Shaari, Sahbudin; Rahman, Mohd Kamil Abd.

    2011-01-01

    We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively.

  10. Nonlinear analysis of wiggler taper, mode competition, and space-charge effects for a 280-GHz free electron laser

    International Nuclear Information System (INIS)

    The nonlinear characteristics of a 280-GHz free electron laser (FEL) are simulated by numerical computation. The three-dimensional set of coupled nonlinear differential equations is solved for a set of TE and TM modes valid for the high gain Compton regime. The use of a nonlinear taper for efficiency enhancement, the sensitivity of gain to competing mode power levels, space-charge effects, and the effect of electron beam source distributions on gain and efficiency are examined for a 10-MeV 3-kA beam. It is found that the nonlinear taper greatly enhances the gain and efficiency and makes the saturation power levels relatively insensitive to the competing mode power levels. The efficiency is increased to 48% by means of a nonlinear taper in which the 3-D and wiggler-averaged codes are compared and the effects of space charge are found to reduce the efficiency to a level of 32%. The effect of beam quality in terms of the four volume phase space is examined and found to have an observable effect at this wavelength

  11. Experimental Measurement of the Static Coefficient of Friction at the Ti-Ti Taper Connection in Total Hip Arthroplasty.

    Science.gov (United States)

    Bitter, T; Khan, I; Marriott, T; Schreurs, B W; Verdonschot, N; Janssen, D

    2016-03-01

    The modular taper junction in total hip replacements has been implicated as a possible source of wear. The finite-element (FE) method can be used to study the wear potential at the taper junction. For such simulations it is important to implement representative contact parameters, in order to achieve accurate results. One of the main parameters in FE simulations is the coefficient of friction. However, in current literature, there is quite a wide spread in coefficient of friction values (0.15 - 0.8), which has a significant effect on the outcome of the FE simulations. Therefore, to obtain more accurate results, one should use a coefficient of friction that is determined for the specific material couple being analyzed. In this study, the static coefficient of friction was determined for two types of titanium-on-titanium stem-adaptor couples, using actual cut-outs of the final implants, to ensure that the coefficient of friction was determined consistently for the actual implant material and surface finish characteristics. Two types of tapers were examined, Biomet type-1 and 12/14, where type-1 has a polished surface finish and the 12/14 is a microgrooved system. We found static coefficients of friction of 0.19 and 0.29 for the 12/14 and type-1 stem-adaptor couples, respectively. PMID:26747129

  12. Assembly-Controlled Permeability of Layer-by-Layer Polymeric Microcapsules Using a Tapered Fluidized Bed.

    Science.gov (United States)

    Noi, Ka Fung; Roozmand, Ali; Björnmalm, Mattias; Richardson, Joseph J; Franks, George V; Caruso, Frank

    2015-12-23

    Nano- and microcapsules engineered through layer-by-layer (LbL) assembly are finding an increasingly large number of applications as catalysts, electrochemical biosensors, bioreactors, artificial cells and drug delivery vehicles. While centrifugation-based LbL assembly is the most common method for coating template particles and preparing capsules, it is a batch process and requires frequent intervention that renders the system challenging to automate and scale up. Here, we report the use of a tapered fluidized bed (TFB) for the preparation of multilayered polymer capsules. This is a significant improvement over our recent approach of fluidizing particles in cylindrical fluidized beds (CFB) for LbL assembly. We demonstrate that TFB is compatible with particles TFB LbL assembly were investigated. The obtained TFB microcapsules demonstrate increased film thickness and roughness compared with those prepared using centrifugation-based LbL assembly. Furthermore, PMASH microcapsules exhibit lower swelling and permeability when prepared via TFB LbL assembly compared with centrifugation-based LbL assembly due to enhanced multilayer deposition, entanglement, and cross-linking. Therefore, polymeric capsules fabricated via TFB LbL assembly may be useful for encapsulation and retention of relatively low molecular weight (∼20 kDa) hydrophilic biomacromolecules to passively or responsively release the payload for drug delivery applications. PMID:26651354

  13. High performances of very long (13.5mm) tapered laser emitting at 975 nm

    Science.gov (United States)

    Resneau, P.; Garcia, M.; Lecomte, M.; Robert, Y.; Vinet, E.; Parillaud, O.; Krakowski, M.; Boiko, D. L.

    2016-03-01

    Mode-locked semiconductor laser technology is a promising technology candidate considered by European Space Agency (ESA) for optical metrology systems and other space applications in the context of high-precision optical metrology, in particular for High Accuracy Absolute Long Distance Measurement. For these applications, we have realised a multi-section monolithic-cavity tapered laser diode with a record cavity length of 13.5 mm. The laser operates at 975 nm wavelength. It is designed for the emission of ultra-short optical pulses (average optical power of 600 mW. It is based on a MOVPE grown laser structure with Aluminium free active region enabling high optical gain, low internal losses and low series resistance. The first results obtained under CW pumping of such centimetre-long laser at 20 °C heatsink temperature show the lasing threshold current as low as 1.27 A and the differential external efficiency as high as 0.55 W/A.

  14. Anomalous Refraction of Acoustic Guided Waves in Solids with Geometrically Tapered Metasurfaces

    Science.gov (United States)

    Zhu, Hongfei; Semperlotti, Fabio

    2016-07-01

    The concept of a metasurface opens new exciting directions to engineer the refraction properties in both optical and acoustic media. Metasurfaces are typically designed by assembling arrays of subwavelength anisotropic scatterers able to mold incoming wave fronts in rather unconventional ways. The concept of a metasurface was pioneered in photonics and later extended to acoustics while its application to the propagation of elastic waves in solids is still relatively unexplored. We investigate the design of acoustic metasurfaces to control elastic guided waves in thin-walled structural elements. These engineered discontinuities enable the anomalous refraction of guided wave modes according to the generalized Snell's law. The metasurfaces are made out of locally resonant toruslike tapers enabling an accurate phase shift of the incoming wave, which ultimately affects the refraction properties. We show that anomalous refraction can be achieved on transmitted antisymmetric modes (A0) either when using a symmetric (S0) or antisymmetric (A0) incident wave, the former clearly involving mode conversion. The same metasurface design also allows achieving structure embedded planar focal lenses and phase masks for nonparaxial propagation.

  15. Voltage distribution in tapered winding of tesla-transformer during discharge process of PFL

    International Nuclear Information System (INIS)

    The operation principle of integral construction of Tesla transformer and PFL was investigated in Tesla-transformer-type accelerator. Experiment was carried out on Tesla transformer's secondary winding to study the impulse voltage distribution while PFL was discharging. The regularities of turn-ground voltage distribution and interturn voltage distribution were summarized. Voltage distribution within PFL was calculated and it was compared with the experimental result. Structural winding of parallel coils in the head, parallel coils in the end and shading ring were used to improve voltage distribution and that was testified by experiment. The results indicate that taper winding doesn't effect electric field within PFL, the turn-ground voltage appears linearly, the interturn voltage fluctuates seriously and it is the biggest in head of winding. The three optimized methods help to depress oscillation, the structural winding of parallel coils in the head decreases the interturn voltage in head of winding remark-ably and the parallel coils in the end decrease the interturn voltage in the end. (authors)

  16. Reconfigured and Notched Tapered Slot UWB Antenna for Cognitive Radio Applications

    Directory of Open Access Journals (Sweden)

    Tamer Aboufoul

    2012-01-01

    Full Text Available A compact reconfigurable and notched ultra-wideband (UWB tapered slot antenna (TSA is presented. The antenna reconfiguration operation principle relies on 2 mechanisms: in the first mechanism a resonator parasitic microstrip line electrically coupled to the TSA is used to notch the TSA at a specific frequency and the second mechanism relies on changing the input impedance matching of the antenna by means of changing the length of a stub line extended from an additional tiny partial ground on the back side of the antenna. The reflection coefficient, radiation patterns, and gain simulations and measurements for the proposed antenna are presented to verify the design concepts featuring a very satisfactory performance. Total efficiency simulations and measurements are also presented to highlight the filtering performance of the reconfigured antenna. When the antenna was reconfigured from the UWB to work into multiple frequency bands, the radiation patterns were still the same and the total peak gain has slightly improved compared to the UWB case. In addition, when the antenna operated in the notched mode, the gain has significantly dropped at the notch frequency. The simplicity and flexibility of the proposed multimode antenna make it a good candidate for future cognitive radio front ends.

  17. High performances of very long (13.5mm) tapered laser emitting at 975 nm

    Science.gov (United States)

    Resneau, P.; Garcia, M.; Lecomte, M.; Robert, Y.; Vinet, E.; Parillaud, O.; Krakowski, M.; Boiko, D. L.

    2016-03-01

    Mode-locked semiconductor laser technology is a promising technology candidate considered by European Space Agency (ESA) for optical metrology systems and other space applications in the context of high-precision optical metrology, in particular for High Accuracy Absolute Long Distance Measurement. For these applications, we have realised a multi-section monolithic-cavity tapered laser diode with a record cavity length of 13.5 mm. The laser operates at 975 nm wavelength. It is designed for the emission of ultra-short optical pulses (power of 600 mW. It is based on a MOVPE grown laser structure with Aluminium free active region enabling high optical gain, low internal losses and low series resistance. The first results obtained under CW pumping of such centimetre-long laser at 20 °C heatsink temperature show the lasing threshold current as low as 1.27 A and the differential external efficiency as high as 0.55 W/A.

  18. A Study of the Anechoic Performance of Rice Husk-Based, Geometrically Tapered, Hollow Absorbers

    Directory of Open Access Journals (Sweden)

    Muhammad Nadeem Iqbal

    2014-01-01

    Full Text Available Although solid, geometrically tapered microwave absorbers are preferred due to their better performance, they are bulky and must have a thickness on the order of λ or more. The goal of this study was to design lightweight absorbers that can reduce the electromagnetic reflections to less than −10 dB. We used a very simple approach; two waste materials, that is, rice husks and tire dust in powder form, were used to fabricate two independent samples. We measured and used their dielectric properties to determine and compare the propagation constants and quarter-wave thickness. The quarter-wave thickness for the tire dust was 3 mm less than that of the rice husk material, but we preferred the rice-husk material. This preference was based on the fact that our goal was to achieve minimum backward reflections, and the rice-husk material, with its low dielectric constant, high loss factor, large attenuation per unit length, and ease of fabrication, provided a better opportunity to achieve that goal. The performance of the absorbers was found to be better (lower than −20 dB, and comparison of the results proved that the hollow design with 58% less weight was a good alternative to the use of solid absorbers.

  19. Investigation on the response of fused taper couplers to ultrasonic wave.

    Science.gov (United States)

    Li, Fengmei; Liu, Yiying; Wang, Linjie; Zhao, Zhenyu

    2015-08-10

    The responses of fused taper couplers with different structure parameters to ultrasonic waves have been investigated theoretically and experimentally. A comprehensive analysis of the acousto-optic interaction was presented, taking into account the elasto-optic geometric effect. It is found that direct deformation of the coupler induced by ultrasonic waves is the critical factor in the sensing mechanism and is closely related to the sensor sensitivity. Moreover, the strain response of the coupler with different structure parameters was analyzed using a 3D coupled acoustic-solid numerical model, which was based on the developed mathematical model. According to the theoretical analyses, related experiments were carried out, and experimental results show that this ultrasonic sensor with a longer stretching length has higher sensitivity and the sensitivity of the sensor takes a nonmonotonic relation with an aspect ratio, which are consistent with the theoretical analyses results. We argue that our work may provide a useful guide in designing and optimizing more sensitive ultrasonic sensors used in practical ultrasonic detection. PMID:26368365

  20. Adsorptive Removal of Para-chlorophenol Using Stratified Tapered Activated Carbon Column

    Institute of Scientific and Technical Information of China (English)

    M.EE Sze; G. McKay

    2012-01-01

    The feasibility of adsorptive removal of single component organic compound (para-chlorophenol) by Calgon Filtrasorb 400 (F400) carbon was investigated. The Redlich-Peterson equation was found to be the best fit model for describing the equilibrium relationship between the para-chlorophenol adsorption onto F400 carbon. Four adsorption columns with different column geometry and adsorbent particle stratification were used to examine the adsorption kinetics onto F400 carbons. The Bed Depth Service Time (BDST) model was applied and modified to analyse the performance of the columns and the effect of different operating variables. When combining the effects of adsorption efficiency and the associated pressure drop of each type of adsorption columns tested, the carbon stratified tapered column has been determined to be the most efficient engineering option for removing organics, in which the enhancement of the adsorbent bed in terms of longer breakthrough time and higher saturation percentage is the greatest amongst the four types of columns with reasonably small pressure drop across the fixed-bed column.

  1. A single-level composite structure optimization method based on a blending tapered model

    Institute of Scientific and Technical Information of China (English)

    An Weigang; Chen Dianyu; Jin Peng

    2013-01-01

    In order to decrease the number of design variables and improve the efficiency of composite structure optimal design,a single-level composite structure optimization method based on a tapered model is presented.Compared with the conventional multi-level composite structure optimization method,this single-level method has many advantages.First,by using a distance variable and a ply group variable,the number of design variables is decreased evidently and independent with the density of sub-regions,which makes the single-level method very suitable for large-scale composite structures.Second,it is very convenient to optimize laminate thickness and stacking sequence in the same level,which probably improves the quality of optimal result.Third,ply continuity can be guaranteed between sub-regions in the single-level method,which could reduce stress concentration and manufacturing difficulty.An example of a composite wing is used to demonstrate the advantages and competence of the single-level method proposed.

  2. Anaerobic tapered fluidized bed reactor for starch wastewater treatment and modeling using multilayer perceptron neural network

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Anaerobic treatability of synthetic sago wastewater was investigated in a laboratory anaerobic tapered fluidized bed reactor (ATFBR) with a mesoporous granular activated carbon (GAC) as a support material. The experimental protocol was defined to examine the effect of the maximum organic loading rate (OLR), hydraulic retention time (HRT), the efficiency of the reactor and to report on its steady-state performance. The reactor was subjected to a steady-state operation over a range of OLR up to 85.44 kg COD/(m3·d). The COD removal efficiency was found to be 92% in the reactor while the biogas produced in the digester reached 25.38 m3/(m3·d) of the reactor. With the increase of OLR from 83.7 kg COD/(m3·d), the COD removal efficiency decreases. Also an artificial neural network (ANN) model using multilayer perceptron (MLP) has been developed for a system of two input variable and five output dependent variables. For the training of the input-output data, the experimental values obtained have been used. The output parameters predicted have been found to be much closer to the corresponding experimental ones and the model was validated for 30% of the untrained data. The mean square error (MSE) was found to be only 0.0146.

  3. All-fiber-integrated single frequency tapered fiber amplifier with near diffraction limited output

    Science.gov (United States)

    Zhou, Zichao; Zhang, Hanwei; Wang, Xiaolin; Pan, Zhiyong; Su, Rongtao; Yang, Baolai; Zhou, Pu; Xu, Xiaojun

    2016-06-01

    We present an all-fiber single frequency high-power amplifier using tapered ytterbium-doped fiber (T-YDF) based on a master oscillator power amplification (MOPA) scheme. Different from previous laser amplifiers, the monolithic system is all-fiber-integrated, employing a large mode area (LMA) T-YDF and co-pump scheme. The LMA T-YDF is 7 m long and its core/inner cladding diameters are 20.4/237.1 μm and 46.9/579.9 μm in the input port and output port, respectively. In experiment, the laser amplifier is shown to generate up to 53 W of single frequency laser with slope efficiency of 57.7%, which indicates more than a two times increase of the stimulated Brillouin scattering (SBS) threshold than common LMA fibers with core/inner cladding diameters of 20/400 μm. At the highest output power, the M 2 factor is measured to be 1.25 and 1.20 in the X and Y directions. Results show that this T-YDF can be scaled up to even higher power when other SBS suppression methods are employed simultaneously.

  4. Transverse pulse shaping and optimization of a tapered hard X-ray free electron laser

    CERN Document Server

    Emma, Claudio; Wu, Juhao

    2014-01-01

    Multidimensional optimization schemes for TW hard X-Ray free electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to examples of transversely Gaussian beams. The optimizations are performed for a $200$m undulator and a resonant wavelength of $\\lambda_r=1.5\\AA $ using the fully 3-dimensional FEL particle code GENESIS. Time dependent simulations showed that the maximum radiation power is larger for flatter transverse distributions due to enhanced optical guiding in the tapered section of the undulator. For a transversely Gaussian beam the maximum output power was found to be $\\text{P}_{max}$=$1.56$ TW compared to $2.26$ TW for the parabolic case and $2.63$ TW for the uniform case. Spectral data also showed a 30-70$\\%$ reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the maximum power as a function of detuning from resonance shows that redshifting the central wavelength by...

  5. Two-Element Tapered Slot Antenna Array for Terahertz Resonant Tunneling Diode Oscillators

    Directory of Open Access Journals (Sweden)

    Jianxiong Li

    2014-01-01

    Full Text Available Two-element tapered slot antenna (TSA array for terahertz (THz resonant tunneling diode (RTD oscillators is proposed in this paper. The proposed TSA array has the advantages of both the high directivity and high gain at the horizontal direction and hence can facilitate the horizontal communication between the RTD oscillators and other integrated circuit chips. A MIM (metal-insulator-metal stub with a T-shaped slot is used to reduce the mutual coupling between the TSA elements. The validity and feasibility of the proposed TSA array have been simulated and analyzed by the ANSYS/ANSOFT’s High Frequency Structure Simulator (HFSS. Detailed modeling approaches and theoretical analysis of the proposed TSA array have been fully addressed. The simulation results show that the mutual coupling between the TSA elements is reduced below −40 dB. Furthermore, at 500 GHz, the directivity, the gain, and the half power beam width (HPBW at the E-plane of the proposed TSA array are 12.18 dB, 13.09 dB, and 61°, respectively. The proposed analytical method and achieved performance are very promising for the antenna array integrated with the RTD oscillators at the THz frequency and could pave the way to the design of the THz antenna array for the RTD oscillators.

  6. Gap-tapered undulators for high-photon-energy synchrotron radiation production

    International Nuclear Information System (INIS)

    Narrow-gap, short-period undulators are of interest to maximize the achievable photon energy at lower-energy storage rings. An important consideration is matching the e-beam beta function in the straight section to the vertical aperture at the insertion device so as to maximize vertical acceptance, beam lifetime, and injection efficiency. Various approaches have been considered such as in-vacuum undulators, undulators with flexible vacuum chambers, and superconducting undulators. In each of these the undulator gap is constant along the undulator length, in which case the optimum beta function is equal to one-half the length. We discuss an alternate approach in which the undulator gap is tapered to follow the transverse profile of the e-beam envelope. This allows the use of a relatively long undulator within a low-beta straight section. The undulator gap is physically and magnetically matched to the e-beam envelope throughout the straight section. The undulator period is varied to maintain constant photon resonance while everywhere maximizing the magnetic field strength. This approach optimizes the high-photon-energy synchrotron radiation generation. The achievable synchrotron radiation spectral properties and tunability of such a device are examined

  7. Design of novel dual-port tapered waveguide plasma apparatus by numerical analysis

    Science.gov (United States)

    Zhang, D.; Zhou, R.; Yang, X. Q.; Wu, S. Y.

    2016-07-01

    Microwave plasma apparatus is often of particular interest due to their superiority of low cost, electrode contamination free, and suitability for industrial production. However, there exist problems of unstable plasma and low electron density in conventional waveguide apparatus based on single port, due to low strength and non-uniformity of microwave field. This study proposes a novel dual-port tapered waveguide plasma apparatus based on power-combining technique, to improve the strength and uniformity of microwave field for the applications of plasma. A 3D model of microwave-induced plasma (field frequency 2.45 GHz) in argon at atmospheric pressure is presented. On the condition that the total input power is 500 W, simulations indicate that coherent power-combining will maximize the electric-field strength to 3.32 × 105 V/m and improve the uniformity of distributed microwave field, which raised 36.7% and 47.2%, respectively, compared to conventional waveguide apparatus of single port. To study the optimum conditions for industrial application, a 2D argon fluid model based on above structure is presented. It demonstrates that relatively uniform and high-density plasma is obtained at an argon flow rate of 200 ml/min. The contrastive result of electric-field distribution, electron density, and gas temperature is also valid and clearly proves the superiority of coherent power-combining to conventional technique in flow field.

  8. Optimization of Electric Power Leveling Systems by using Taper-Off-Reflectance Particle Swarm Optimization

    Science.gov (United States)

    Makino, Yohei; Fujii, Toshinori; Imai, Jun; Funabiki, Shigeyuki

    Recently, it is desired to develop energy control technologies for environmental issues such as global warming and exhaustion of fossil fuel. Power fluctuations in large power consumers may cause the instability of electric power systems and increase the cost of the electric power facility and electricity charges. Developing the electric power-leveling systems (EPLS) to compensate the power fluctuations is necessary for future electric power systems. Now, EPLS with an SMES have been proposed as one of the countermeasures for the electric power quality improvement. The SMES is superior to other energy storage devices in response and storage efficiency. The authors proposed the EPLS based on fussy control with the SMES. For this practical implementation, optimizing control gain and SMES capacity is an important issue. This paper proposes a new optimization method of the EPLS. The proposed algorithm is novel particle swarm optimization based on taper-off reflectance (TRPSO). The proposed TRPSO optimizes the design variables of the EPLS efficiently and effectively.

  9. Foreign Body Retrieval

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Foreign Body Retrieval Foreign body retrieval is the removal ... of foreign body detection and removal? What is Foreign Body Retrieval? Foreign body retrieval involves the removal ...

  10. Mechanical and thermo-mechanical analyses of the tapered plug for plugging of deposition tunnels. A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Faelth, Billy (Clay Technology AB, Lund (Sweden)); Gatter, Patrik (Vattenfall Power Consultant AB, Stockholm (Sweden))

    2009-09-15

    This report presents results from a study that was carried out in order to examine the applicability of the tapered plug concept for plugging of deposition tunnels in the deep repository for spent nuclear fuel. The report presents results from mechanical and thermo-mechanical models of the tapered plug. The models were analyzed with 3DEC. The models included a portion of a deposition tunnel and its intersection with a main tunnel. In the deposition tunnel, a tapered concrete plug was installed. The plug was subjected to the combined load from the swelling backfill material and from pore pressure inside the deposition tunnel. The thermo-mechanical effects due to the heat generation in the spent fuel were also included in the analyses. Generic material parameter values for the concrete were used. The following items were studied: - Stresses and displacements in the plug. - Shear stresses and shear displacements in the rock-concrete interface. - Stress additions in the rock due to the loads. The sensitivity of the results to changes of constitutive models, to changes of the plug geometry and to pore water pressure in the rock-concrete interface was examined. The results indicate that the displacements in the plug will be within reasonable ranges but the stresses may locally be high enough that they exceed acceptable levels. However, they can be reduced by choice of advantageous plug geometry and by having a good rock-concrete bond. The results also show that the stress additions in the rock due to the thermal load may yield stresses that locally exceed the spalling strength of the rock. At most locations, however, the rock stresses will amount at lower levels. It was concluded that, with choice of an appropriate design, the tapered plug seems to be an applicable concept for plugging of deposition tunnels. It was also concluded that further studies of the tapered plug concept should use material properties parameter values for low-pH concrete. Further, they should also

  11. Mechanical and thermo-mechanical analyses of the tapered plug for plugging of deposition tunnels. A feasibility study

    International Nuclear Information System (INIS)

    This report presents results from a study that was carried out in order to examine the applicability of the tapered plug concept for plugging of deposition tunnels in the deep repository for spent nuclear fuel. The report presents results from mechanical and thermo-mechanical models of the tapered plug. The models were analyzed with 3DEC. The models included a portion of a deposition tunnel and its intersection with a main tunnel. In the deposition tunnel, a tapered concrete plug was installed. The plug was subjected to the combined load from the swelling backfill material and from pore pressure inside the deposition tunnel. The thermo-mechanical effects due to the heat generation in the spent fuel were also included in the analyses. Generic material parameter values for the concrete were used. The following items were studied: - Stresses and displacements in the plug. - Shear stresses and shear displacements in the rock-concrete interface. - Stress additions in the rock due to the loads. The sensitivity of the results to changes of constitutive models, to changes of the plug geometry and to pore water pressure in the rock-concrete interface was examined. The results indicate that the displacements in the plug will be within reasonable ranges but the stresses may locally be high enough that they exceed acceptable levels. However, they can be reduced by choice of advantageous plug geometry and by having a good rock-concrete bond. The results also show that the stress additions in the rock due to the thermal load may yield stresses that locally exceed the spalling strength of the rock. At most locations, however, the rock stresses will amount at lower levels. It was concluded that, with choice of an appropriate design, the tapered plug seems to be an applicable concept for plugging of deposition tunnels. It was also concluded that further studies of the tapered plug concept should use material properties parameter values for low-pH concrete. Further, they should also

  12. Assembly force and taper angle difference influence the relative motion at the stem-neck interface of bi-modular hip prostheses.

    Science.gov (United States)

    Haschke, Henning; Jauch-Matt, Sabrina Y; Sellenschloh, Kay; Huber, Gerd; Morlock, Michael M

    2016-07-01

    Bi-modular hip arthroplasty prostheses allow adaptation to the individual patient anatomy and the combination of different materials but introduce an additional interface, which was related lately to current clinical issues. Relative motion at the additional taper interface might increase the overall risk of fretting, corrosion, metallic debris and early failure. The aim of this study was to investigate whether the assembly force influences the relative motion and seating behaviour at the stem-neck interface of a bi-modular hip prosthesis (Metha(®); Aesculap AG, Tuttlingen, Germany) and whether this relation is influenced by the taper angle difference between male and female taper angles. Neck adapters made of titanium (Ti6Al4V) and CoCr (CoCr29Mo) were assembled with a titanium stem using varying assembly forces and mechanically loaded. A contactless eddy current measurement system was used to record the relative motion between prosthesis stem and neck adapter. Higher relative motion was observed for Ti neck adapters compared to the CoCr ones (p < 0.001). Higher assembly forces caused increased seating distances (p < 0.001) and led to significantly reduced relative motion (p = 0.019). Independent of neck material type, prostheses with larger taper angle difference between male and female taper angles exhibited decreased relative motion (p < 0.001). Surgeons should carefully use assembly forces above 4 kN to decrease the amount of relative motion within the taper interface. Maximum assembly forces, however, should be limited to prevent periprosthetic fractures. Manufacturers should optimize taper angle differences to increase the resistance against relative motion. PMID:27170535

  13. All-optical control of electron self-injection in millimeter-scale, tapered dense plasmas

    International Nuclear Information System (INIS)

    It is demonstrated that a laser pulse with an ultrahigh bandwidth (Δλ∼400 nm) is an asset for future high-repetition-rate, quasimonoenergetic (QME), GeV-scale laser plasma electron accelerators. Manipulating the phase of the driver has a direct impact on evolution of the accelerating bucket (a cavity of electron density maintained by the pressure of the laser pulse radiation), making it possible to control electron self-injection and the final parameters of the QME beam by purely optical means. The large bandwidth makes it possible to compensate for the frequency red-shift accumulated at the pulse leading edge in transit through the plasma. Advancing higher frequencies in time (viz. introducing a negative frequency chirp of the incident pulse) reduces the red-shift, preventing self-compression of the pulse into a relativistic optical shock. This avoids constant expansion of the plasma bucket, suppressing continuous self-injection of copious unwanted electrons, keeping the beam almost free of a high-charge, poorly collimated low-energy tail. In addition, gradually increasing the plasma density in the forward direction locks electrons in the accelerating phase, delaying their dephasing and boosting their energy without increasing the tail. Advantages of this technique are demonstrated here for acceleration in sub-millimeter-length, dense plasmas (n0>1019cm−3), using 100-mJ-scale energy laser pulses. Three-dimensional particle-in-cell simulations show that a negatively chirped, 15 TW pulse with a 20 fs length and a bandwidth corresponding to a transform-limited duration below two optical cycles, in combination with a modest density taper (corresponding to 25% linear increase of the density in the forward direction), transfers 3.5% of its energy to a 300 MeV electron bunch with relative energy spread below 4% and flux a factor 4.5 higher than the average flux in the tail. The acceleration occurs over a 0.6 mm plasma with the electron density at the center of the

  14. All-optical control of electron self-injection in millimeter-scale, tapered dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kalmykov, S.Y., E-mail: serguei.kalmykov@yahoo.com [Department of Physics and Astronomy, University of Nebraska—Lincoln, Lincoln, NE 68588-0299 (United States); Davoine, X. [CEA, DAM, DIF, Arpajon F-91297 (France); Shadwick, B.A. [Department of Physics and Astronomy, University of Nebraska—Lincoln, Lincoln, NE 68588-0299 (United States)

    2014-03-11

    It is demonstrated that a laser pulse with an ultrahigh bandwidth (Δλ∼400 nm) is an asset for future high-repetition-rate, quasimonoenergetic (QME), GeV-scale laser plasma electron accelerators. Manipulating the phase of the driver has a direct impact on evolution of the accelerating bucket (a cavity of electron density maintained by the pressure of the laser pulse radiation), making it possible to control electron self-injection and the final parameters of the QME beam by purely optical means. The large bandwidth makes it possible to compensate for the frequency red-shift accumulated at the pulse leading edge in transit through the plasma. Advancing higher frequencies in time (viz. introducing a negative frequency chirp of the incident pulse) reduces the red-shift, preventing self-compression of the pulse into a relativistic optical shock. This avoids constant expansion of the plasma bucket, suppressing continuous self-injection of copious unwanted electrons, keeping the beam almost free of a high-charge, poorly collimated low-energy tail. In addition, gradually increasing the plasma density in the forward direction locks electrons in the accelerating phase, delaying their dephasing and boosting their energy without increasing the tail. Advantages of this technique are demonstrated here for acceleration in sub-millimeter-length, dense plasmas (n{sub 0}>10{sup 19}cm{sup −3}), using 100-mJ-scale energy laser pulses. Three-dimensional particle-in-cell simulations show that a negatively chirped, 15 TW pulse with a 20 fs length and a bandwidth corresponding to a transform-limited duration below two optical cycles, in combination with a modest density taper (corresponding to 25% linear increase of the density in the forward direction), transfers 3.5% of its energy to a 300 MeV electron bunch with relative energy spread below 4% and flux a factor 4.5 higher than the average flux in the tail. The acceleration occurs over a 0.6 mm plasma with the electron density at

  15. Evaluation of apical deviation in root canals instrumented with K3 and ProTaper systems Avaliação do desvio apical em canais instrumentados pelos sistemas K3 e ProTaper

    Directory of Open Access Journals (Sweden)

    Mariana Diniz Bisi dos Santos

    2006-12-01

    Full Text Available OBJECTIVES: this study evaluated the apical deviation of curved root canals instrumented with K3 and ProTaper systems. MATERIAL AND METHODS: twenty root canals of human maxillary and mandibular first molars were employed, which were divided into 2 groups: group A (10 teeth was instrumented with the K3 system, and group B (10 teeth with the ProTaper system. Evaluation of deviation was performed by double radiographic exposure. Radiographs were achieved before and after instrumentation, with 0.3-second, thus allowing superimposition of images. Three-dimensional computerized tomograph was performed in 3 specimens in each group, as an additional means to evaluate the apical deviation. RESULTS: were evaluated by the parametric test Student-Newman-Keuls at 5%, which did not reveal significance between groups concerning the apical deviation. The results of computerized tomograph images demonstrated that the larger deviation of the root canal occurred at the distolingual area for both systems. CONCLUSIONS: both techniques produced a mild apical deviation. Computerized microtomography was shown to be accurate for experimental endodontics studies.OBJETIVOS: avaliar o desvio apical de canais radiculares curvos instrumentados pelos sistemas K3 e ProTaper. MATERIAIS E MÉTODOS: foram utilizados 20 canais radiculares de primeiros molares superiores e inferiores humanos, os quais foram divididos em 2 grupos, o grupo A (10 dentes foi instrumentado pelo sistema K3 e o grupo B (10 dentes com o sistema ProTaper, a forma de avaliação do desvio foi a dupla exposição radiográfica. As tomadas radiográficas foram feitas antes e após a instrumentação, com um tempo de 0,3 segundos em cada exposição, ocorrendo assim, sobreposição das imagens. Em 3 espécimes, de cada grupo, foi realizada a tomografia computadorizada tridimensional, como forma adicional de avaliar o desvio apical . Os resultados obtidos foram avaliados pelo teste paramétrico Student

  16. Dementia with Lewy Bodies

    Science.gov (United States)

    ... Awards Enhancing Diversity Find People About NINDS NINDS Dementia With Lewy Bodies Information Page Synonym(s): Lewy Body ... and Information Additional resources from MedlinePlus What is Dementia With Lewy Bodies? Dementia with Lewy bodies (DLB) ...

  17. Evaluation of the insertion efficiencies of tapered silicon nanoneedles and invasiveness of diamond nanoneedles in manipulations of living single cells.

    Science.gov (United States)

    Han, Sung-Woong; Ryu, Seunghwan; Kitagawa, Taro; Uetsuka, Hiroshi; Fujimori, Naoji; Aoki, Yukihiro; Ota, Ryo; Amemiya, Yosuke; Shimamoto, Nobuo; Nakamura, Chikashi; Miyake, Jun

    2009-01-01

    We have been developing a low invasive cell manipulation technology based on inserting an ultra-thin needle--"nanoneedle"--into a living cell by using an atomic force microscope (AFM). The nanoneedle, made from a silicon AFM tip by focused-ion-beam etching, has a diameter of several hundred nanometers and a length of about 10 microns. Successful insertion of the nanoneedle into the cell can be confirmed by the appearance of a steep relaxation of repulsive force in the force-distance curve as monitored by the AFM system. This technology, termed "cell surgery", can be applied for the detection of intracellular proteins in a living cell or for highly efficient gene transfer. The present study shows that the durability of a tapered nanoneedle is superior to that of a cylindrical nanoneedle, and that a proper aspect ratio for the tapered nanoneedle must be chosen to maintain sufficient insertion efficiency for a particular target cell: tapered nanoneedles of an aspect ratio over 20 showed high insertion efficiency for various kinds of mammalian cells. We then used diamond for the material of the nanoneedle because its specific properties, such as high stiffness, heat conductivity, and electrical conductivity capacitated by boron doping, were deemed useful for the analysis and manipulation of intracellular phenomena. We compared the capability of the diamond nanoneedle in cell manipulation with that of the silicon nanoneedle. Evaluation of the effect of the former on transcription efficiency and localization analysis of p53 expression revealed the low invasiveness for cell manipulation as was also the case for the silicon nanoneedle. We also succeeded in achieving highly efficient plasmid DNA delivery into a mouse fibroblast C3H10T1/2 using the diamond nanoneedle. The diamond nanoneedle is expected to contribute to the versatility of "cell surgery" technology. PMID:21471661

  18. Good clinical practice guide for opioids in pain management: the three Ts - titration (trial, tweaking (tailoring, transition (tapering

    Directory of Open Access Journals (Sweden)

    Flaminia Coluzzi

    2016-06-01

    Full Text Available ABSTRACT BACKGROUND AND OBJECTIVES: Achieving good clinical practice in the use of opioids as part of a comprehensive pain management regimen can face significant challenges. Despite guidelines from governmental and pain society/organization sources, there are still significant hurdles. A review of some basic tenets of opioid analgesia based on current published knowledge and experiences about this important healthcare imperative is warranted. CONTENT: Consistent with guidelines, the literature supports using the lowest total opioid dose that provides adequate pain control with the fewest adverse effects. Titration (or trial during opioid initiation is a way of starting low and going slow (and assessing the appropriateness of a specific opioid and formulation. Recognizing that multiple factors contribute to an individual's personal experience of pain, the physical, psychological, social, cultural, spiritual, pharmacogenomic, and behavioral factors of the individual patient should be taken into account (tweaking, or tailoring. Finally, for those patients for whom transition (tapering from opioid is desired, doing so too rapidly can have negative consequences and minimization of problems during this step can be achieved by proper tapering. CONCLUSION: We conclude that a simultaneously aggressive, yet conservative, approach is advocated in the literature in which opioid therapy is divided into three key steps (the 3 T's: titration (or trial, tweaking (or tailoring, and transition (or tapering. Establishment of the 3 T's along with the application of other appropriate good medical practice and clinical experience/judgment, including non-pharmacologic approaches, can assist healthcare providers in the effort to achieve optimal management of pain.

  19. Total heat loss coefficient of flat roof constructions with external insulation in tapered layers including the effects of thermal bridges

    DEFF Research Database (Denmark)

    Rose, Jørgen; Svendsen, Svend

    2005-01-01

    be quite tedious, and therefore a method to generate and optimize solutions has been developed and implemented in a program that also takes into account the effects of different types of thermal bridges, i.e. roof windows, insulation fasteners, roof/wall joints etc. This paper describes a new method...... for design of flat roofs and a pc-program that can be used for calculating the total heat loss coefficient of externally insulated roofs with insulation in tapered layers, taking into account thermal bridges in the roof construction....

  20. Separation and Recovery of Fine Particles from Waste Circuit Boards Using an Inflatable Tapered Diameter Separation Bed

    OpenAIRE

    2014-01-01

    Recovering particle materials from discarded printed circuit boards can enhance resource recycling and reduce environmental pollution. Efficiently physically separating and recovering fine metal particles (−0.5 mm) from the circuit boards are a key recycling challenge. To do this, a new type of separator, an inflatable tapered diameter separation bed, was developed to study particle motion and separation mechanisms in the bed’s fluid flow field. For 0.5–0.25 mm circuit board particles, metal ...

  1. High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability

    Directory of Open Access Journals (Sweden)

    Andreas Schmitt-Sody

    2008-01-01

    Full Text Available We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.

  2. Tunable high-power narrow-spectrum external-cavity diode laser based on tapered amplifier at 668 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Erbert, G.; Sumpf, B.;

    2010-01-01

    A 668 nm tunable high-power narrow-spectrum diode laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The laser system is tunable from 659 to 675 nm. As high as 1.38 W output power is obtained at 668.35 nm. The emission spectral bandwidth is less than...... 0.07 nm throughout the tuning range, and the beam quality factor M2 is 2.0 with the output power of 1.27 W....

  3. Nanosecond Pulse Shaping with Fiber-Based Electro-Optical Modulators and a Double-Pass Tapered Amplifier

    CERN Document Server

    Rogers, Charles E

    2015-01-01

    We describe a system for generating frequency-chirped and amplitude-shaped pulses on time scales from sub-nanosecond to ten nanoseconds. The system starts with cw diode-laser light at 780 nm and utilizes fiber-based electro-optical phase and intensity modulators, driven by an arbitrary waveform generator, to generate the shaped pulses. These pulses are subsequently amplified to several hundred mW with a tapered amplifier in a delayed double-pass configuration. Frequency chirps up to 5 GHz in 2 ns and pulse widths as short as 0.15 ns have been realized.

  4. Study of the interaction between the 180 keV O6+ ions and the tapered glass capillary

    International Nuclear Information System (INIS)

    Transmission of 180 keV O6+ ions through a tapered glass macro-capillary has been investigated, in which high incident current with a magnitude of several nA/mm2 was employed. It is found that the current density was enhanced by 6∼7 times after the ions transmitted through the capillary. The transmitted ions kept their original charge state and energy. It is found that the transmitted ions were deflected away from its incident direction for a small angle when the capillary was tilted. Experimental results were discussed with the self-organized charging-up model. (authors)

  5. Suppression and splitting of modulational instability sidebands in periodically tapered optical fibers because of fourth-order dispersion.

    Science.gov (United States)

    Armaroli, Andrea; Biancalana, Fabio

    2014-08-15

    We study the modulational instability induced by periodic variations of group-velocity dispersion in the proximity of the zero dispersion point. Multiple instability peaks originating from parametric resonance coexist with the conventional modulation instability because of fourth-order dispersion, which in turn is suppressed by the oscillations of dispersion. Moreover, isolated unstable regions appear in the space of parameters because of imperfect phase matching. This confirms the dramatic effect of periodic tapering in the control and shaping of MI sidebands in optical fibers. PMID:25121879

  6. Analysis of dose distributions for 4 MV X rays for symmetrical and offset fields using tapered multi-leaf collimators

    International Nuclear Information System (INIS)

    Dose distributions for 4 MV X rays for symmetrical and offset fields using tapered multi-leaf collimators were measured with a computer controlled dosimeter system and analysis of the obtained data was carried out. Off-center axis ratios (OCR) for square and rectangular fields were different in the region of low dose. The equation for the correction was shown. OCR's for offset fields were almost the same as those for symmetrical fields when the field widths were less than about 10 cm and the depths were greater than about 6 cm. (author)

  7. The influence of temperature to a refractive index sensor based on a macro-bending tapered plastic optical fiber

    Science.gov (United States)

    Teng, Chuan-xin; Yu, Fang-da; Jing, Ning; Zheng, Jie

    2016-09-01

    The temperature influence to a refractive index (RI) sensor based on a macro-bending tapered plastic optical fiber (POF) was investigated experimentally. The total temperature dependence loss (TDLtotal) and total temperature dependence RI deviation (TDRtotal) were measured at different temperature (10-60 °C) over an RI range of 1.33-1.41. The temperature dependence RI deviation of the sensor itself was obtained by subtracting the temperature dependence RI of measured liquid from TDRtotal. Therefore, the influence of temperature variation to the sensor was characterized and corrected.

  8. Self-focusing and self-compression of a laser pulse in the presence of an external tapered magnetized density-ramp plasma

    Science.gov (United States)

    Saedjalil, N.; Jafari, S.

    2016-06-01

    In this paper, the effects of external tapered axial magnetic field and plasma density-ramp on the spatiotemporal evolution of the laser pulse in inhomogeneous plasma have been studied. The external magnetic field can modify the refractive index of plasma and consequently intensifies the nonlinear effects. By considering the relativistic nonlinearity effect, self-focusing and self-compression of the laser beam propagating through the magnetized plasma have been investigated, numerically. Numerical results indicate that self-focusing and self-compression are better enhanced in a tapered magnetic field than in a uniform one. Besides, in plasma density-ramp profile, self-focusing and self-compression of the laser beam improve in comparison with no ramp structure. In addition, with increasing both the slope of the density ramp and slope constant parameter of the tapered magnetic field, the laser focusing increases, properly, in short distances of the laser propagation through the plasma.

  9. Separation and recovery of fine particles from waste circuit boards using an inflatable tapered diameter separation bed.

    Science.gov (United States)

    Duan, Chenlong; Sheng, Cheng; Wu, Lingling; Zhao, Yuemin; He, Jinfeng; Zhou, Enhui

    2014-01-01

    Recovering particle materials from discarded printed circuit boards can enhance resource recycling and reduce environmental pollution. Efficiently physically separating and recovering fine metal particles (-0.5 mm) from the circuit boards are a key recycling challenge. To do this, a new type of separator, an inflatable tapered diameter separation bed, was developed to study particle motion and separation mechanisms in the bed's fluid flow field. For 0.5-0.25 mm circuit board particles, metal recovery rates ranged from 87.56 to 94.17%, and separation efficiencies ranged from 87.71 to 94.20%. For 0.25-0.125 mm particles, metal recovery rates ranged from 84.76 to 91.97%, and separation efficiencies ranged from 84.74 to 91.86%. For superfine products (-0.125 mm), metal recovery rates ranged from 73.11 to 83.04%, and separation efficiencies ranged from 73.00 to 83.14%. This research showed that the inflatable tapered diameter separation bed achieved efficient particle separation and can be used to recover fine particles under a wide range of operational conditions. The bed offers a new mechanical technology to recycle valuable materials from discarded printed circuit boards, reducing environmental pollution. PMID:25379546

  10. Separation and Recovery of Fine Particles from Waste Circuit Boards Using an Inflatable Tapered Diameter Separation Bed

    Directory of Open Access Journals (Sweden)

    Chenlong Duan

    2014-01-01

    Full Text Available Recovering particle materials from discarded printed circuit boards can enhance resource recycling and reduce environmental pollution. Efficiently physically separating and recovering fine metal particles (−0.5 mm from the circuit boards are a key recycling challenge. To do this, a new type of separator, an inflatable tapered diameter separation bed, was developed to study particle motion and separation mechanisms in the bed’s fluid flow field. For 0.5–0.25 mm circuit board particles, metal recovery rates ranged from 87.56 to 94.17%, and separation efficiencies ranged from 87.71 to 94.20%. For 0.25–0.125 mm particles, metal recovery rates ranged from 84.76 to 91.97%, and separation efficiencies ranged from 84.74 to 91.86%. For superfine products (−0.125 mm, metal recovery rates ranged from 73.11 to 83.04%, and separation efficiencies ranged from 73.00 to 83.14%. This research showed that the inflatable tapered diameter separation bed achieved efficient particle separation and can be used to recover fine particles under a wide range of operational conditions. The bed offers a new mechanical technology to recycle valuable materials from discarded printed circuit boards, reducing environmental pollution.

  11. Effect of radiation and magnetic field on peristaltic transport of nanofluids through a porous space in a tapered asymmetric channel

    Energy Technology Data Exchange (ETDEWEB)

    Kothandapani, M., E-mail: mkothandapani@gmail.com [Department of Mathematics, University College of Engineering Arni, (A Constituent College of Anna University Chennai), Arni 632326, Tamil Nadu (India); Prakash, J., E-mail: prakashjayavel@yahoo.co.in [Department of Mathematics, Arulmigu Meenakshi Amman College of Engineering, Vadamavandal 604410, Tamil Nadu (India)

    2015-03-15

    Theoretical analyses on the effect of radiation and MHD on the peristaltic flow of a nanofluid through a porous medium in a two dimensional tapered asymmetric channel has been made. The nanofluid is assumed to be electrically conducting in the presence of a uniform magnetic field. The transport equation accounts the both Brownian motion and thermophoresis along with the radiation reaction. The problem has been further simplified with the authentic assumptions of long wavelength and small Reynolds number. The analytical expressions obtained for the axial velocity, stream function, temperature field, nanoparticle fraction field and pressure gradient provide satisfactory explanation. Influence of various parameters on the flow characteristics have been discussed with the help of graphical results. The trapping phenomenon has also been discussed in detail. - Highlights: • Combine effect of thermal radiation and MHD on the peristaltic flow of a Newtonian nanofluid are discussed. • This work may be first attempt dealing the study of Newtonian nanofluid flow in the porous tapered asymmetric channel. • The velocity, stream function, temperature field and nanoparticle fraction field provide satisfactory explanation with help of graphs.

  12. Effect of radiation and magnetic field on peristaltic transport of nanofluids through a porous space in a tapered asymmetric channel

    International Nuclear Information System (INIS)

    Theoretical analyses on the effect of radiation and MHD on the peristaltic flow of a nanofluid through a porous medium in a two dimensional tapered asymmetric channel has been made. The nanofluid is assumed to be electrically conducting in the presence of a uniform magnetic field. The transport equation accounts the both Brownian motion and thermophoresis along with the radiation reaction. The problem has been further simplified with the authentic assumptions of long wavelength and small Reynolds number. The analytical expressions obtained for the axial velocity, stream function, temperature field, nanoparticle fraction field and pressure gradient provide satisfactory explanation. Influence of various parameters on the flow characteristics have been discussed with the help of graphical results. The trapping phenomenon has also been discussed in detail. - Highlights: • Combine effect of thermal radiation and MHD on the peristaltic flow of a Newtonian nanofluid are discussed. • This work may be first attempt dealing the study of Newtonian nanofluid flow in the porous tapered asymmetric channel. • The velocity, stream function, temperature field and nanoparticle fraction field provide satisfactory explanation with help of graphs

  13. Rigorous surface enhanced Raman spectral characterization of large-area high-uniformity silver-coated tapered silica nanopillar arrays

    Science.gov (United States)

    Gartia, Manas R.; Xu, Zhida; Behymer, Elaine; Nguyen, Hoang; Britten, Jerald A.; Larson, Cindy; Miles, Robin; Bora, Mihail; S-P Chang, Allan; Bond, Tiziana C.; Logan Liu, G.

    2010-10-01

    Surface enhanced Raman spectroscopy (SERS) has been increasingly utilized as an analytical technique with significant chemical and biological applications (Qian et al 2008 Nat. Biotechnol. 26 83; Fujita et al 2009 J. Biomed. Opt. 14 024038; Chou et al 2008 Nano Lett.8 1729; Culha et al 2003 Anal. Chem. 75 6196; Willets K A 2009 Anal. Bioanal. Chem. 394 85; Han et al 2009 Anal. Bioanal. Chem. 394 1719; Sha et al 2008 J. Am. Chem. Soc. 130 17214). However, production of a robust, homogeneous and large-area SERS substrate with the same ultrahigh sensitivity and reproducibility still remains an important issue. Here, we describe a large-area ultrahigh-uniformity tapered silver nanopillar array made by laser interference lithography on the entire surface of a 6 inch wafer. Also presented is the rigorous optical characterization method of the tapered nanopillar substrate to accurately quantify the Raman enhancement factor, uniformity and repeatability. An average homogeneous enhancement factor of close to 108 was obtained for benzenethiol adsorbed on a silver-coated nanopillar substrate.

  14. Tapering the sky response for angular power spectrum estimation from low-frequency radio-interferometric data

    CERN Document Server

    Choudhuri, Samir; Roy, Nirupam; Ghosh, Abhik; Ali, Sk Saiyad

    2016-01-01

    It is important to correctly subtract point sources from radio-interferometric data in order to measure the power spectrum of diffuse radiation like the Galactic synchrotron or the Epoch of Reionization 21-cm signal. It is computationally very expensive and challenging to image a very large area and accurately subtract all the point sources from the image. The problem is particularly severe at the sidelobes and the outer parts of the main lobe where the antenna response is highly frequency dependent and the calibration also differs from that of the phase center. Here we show that it is possible to overcome this problem by tapering the sky response. Using simulated 150 MHz observations, we demonstrate that it is possible to suppress the contribution due to point sources from the outer parts by using the Tapered Gridded Estimator to measure the angular power spectrum C_l of the sky signal. We also show from the simulation that this method can self-consistently compute the noise bias and accurately subtract it t...

  15. Experimental study on the standing-wave tube with tapered section and its extremely nonlinear standing-wave field

    Institute of Scientific and Technical Information of China (English)

    MIN Qi; YIN Yao; LI Xiaodong; LIU Ke

    2011-01-01

    A standing-wave tube with tapered section (STTS) was evolved from a standingwave tube with abrupt section (STAS) whose abrupt section was replaced with tapered section. The research was intended to compare the acoustic properties and the extremely nonlinear pure standing waves of STTS with those of STAS. The acoustic properties of the STTS were studied with transfer matrix. It was proved, like the STAS, that the STTS was dissonant standingwave tube. With its dissonant property, the 181 dB extremely nonlinear pure standing wave was obtained in the STTS excited at its first resonance frequency. Then the comparative experimental studies on the saturation properties of the extremely nonlinear standing waves were carried out in the STTS and the STAS with the same length. It was found that the STTS could suppress the harmonics and meanwhile reduce energy loss of the standing wave more effectively. Compared with the STAS, under the same voltage of loudspeaker, the STTS obtained a higher extremely nonlinear pure standing wave. Moreover, it was found for the STTS that the third harmonic of the third resonance frequency was close to the seventh resonance frequency of sound source impedance, to which the valley value of the sound pressure level transfer function corresponded. Because of this, the third harmonic increased rapidly with the increase of fundamental wave and tended to saturate.

  16. Tapering the sky response for angular power spectrum estimation from low-frequency radio-interferometric data

    Science.gov (United States)

    Choudhuri, Samir; Bharadwaj, Somnath; Roy, Nirupam; Ghosh, Abhik; Ali, Sk. Saiyad

    2016-06-01

    It is important to correctly subtract point sources from radio-interferometric data in order to measure the power spectrum of diffuse radiation like the Galactic synchrotron or the Epoch of Reionization 21-cm signal. It is computationally very expensive and challenging to image a very large area and accurately subtract all the point sources from the image. The problem is particularly severe at the sidelobes and the outer parts of the main lobe where the antenna response is highly frequency dependent and the calibration also differs from that of the phase centre. Here, we show that it is possible to overcome this problem by tapering the sky response. Using simulated 150 MHz observations, we demonstrate that it is possible to suppress the contribution due to point sources from the outer parts by using the Tapered Gridded Estimator to measure the angular power spectrum Cℓ of the sky signal. We also show from the simulation that this method can self-consistently compute the noise bias and accurately subtract it to provide an unbiased estimation of Cℓ.

  17. Closed-form empirical relations to predict the dynamic pull-in parameters of electrostatically actuated tapered microcantilevers

    International Nuclear Information System (INIS)

    We develop novel closed-form empirical relations to estimate the dynamic pull-in parameters of electrostatically actuated linearly tapered microcantilever beams driven by a step-function voltage. A computationally efficient single degree-of-freedom model is employed in the setting of an energy-based technique to characterize the dynamic pull-in of the distributed electromechanical model that takes into account the effects of fringing field capacitance. The model exploits the fundamental mode shape of the respective nonprismatic geometry obtained using the differential transform technique. A unique surface fitting model is proposed to characterize the variations of both pull-in displacement and pull-in voltage over a realistically wide range of system parameters. Optimum coefficients of the proposed surface fitting model are obtained using nonlinear regression analysis. The empirical estimates of dynamic pull-in parameters are validated against 3D finite element simulations and available data in the literature. Excellent agreement indicates that the proposed relationships are sufficiently accurate to be safely used for the preliminary design of tapered microcantilever beams.

  18. Design, test, and operation of new tapered stripline injection kickers for the e+e- collider DAΦNE

    Science.gov (United States)

    Alesini, David; Guiducci, Susanna; Marcellini, Fabio; Raimondi, Pantaleo

    2010-11-01

    For the injection upgrade of the Φ factory DAΦNE, new fast stripline kickers have been designed. They can operate with very short pulse generators to perturb only the injected bunch and the two stored adjacent ones. The design is based on tapering the striplines to simultaneously obtain low beam coupling and transfer impedances, excellent uniformity of the deflecting field, and better matching between the strip and the pulse generators. It has been done using 2D and 3D electromagnetic codes (Superfish and HFSS). The kickers have been constructed, tested, and installed in the collider. Measurements of the reflection coefficient at input ports and of the longitudinal and transverse beam coupling impedance have been also performed to characterize the structure and have been compared to the simulation results. A circuital model of general tapered striplines for a first order estimation of the transfer and longitudinal beam coupling impedances is also presented. Finally operational performances are described, pointing out the problems which occurred and the flexibility of the stripline structures that worked with both the short and with the previously installed long pulse generators and have been used as an additional damping kicker to improve the efficiency of the horizontal multibunch feedback system. This system is also a demonstration of the operation of fast kickers with similar characteristics as those for the International Linear Collider (ILC) damping rings (DRs).

  19. The effect of electropolishing on torque and force during simulated root canal preparation with ProTaper shaping files.

    Science.gov (United States)

    Boessler, Claudia; Paque, Frank; Peters, Ove A

    2009-01-01

    Surface modifications of nickel-titanium instruments such as electropolishing may reduce fracture incidence but could potentially alter the instruments' mechanical properties. We studied the impact of two surface types, machined and electropolished, of ProTaper shaping files on torque and force during simulated root canal preparation. Pilot holes of 0.5-mm diameter were drilled perpendicularly through 3-mm thick human dentin discs and served as standardized simulated root canals (SSRCs). A total of 300 SSRCs were prepared with ProTaper Sx, S1, and S2 instruments using an automated testing platform. Maximum torque (in Ncm) and maximum force values (in N) were measured. In three experimental groups (Sx, S1, and S2) preparation of SSRCs was performed using electropolished versus machined instruments in the same dentin disc. For all three tested instruments, peak torque was higher for electropolished files; apically exerted forces were similar, except for Sx, in which machined instruments developed higher forces. We conclude that surface treatment by electropolishing alters the cutting ability of nickel-titanium rotary instruments. PMID:19084135

  20. Effect of Preparation Taper, Height and Marginal Design Under Varying Occlusal Loading Conditions on Cement Lute Stress: A Three Dimensional Finite Element Analysis

    OpenAIRE

    Tripathi, Siddhi; Amarnath, Gowdagere Shamanna; Muddugangadhar, Byrasandra Channapa; Sharma, Ashish; Choudhary, Suchismita

    2014-01-01

    To assess the effect of preparation taper, height and margin design under different loading conditions on cement lute stress. A 3-D FE model of an upper second premolar and molar was developed from CT scan of human skull using software programmes (MIMICS, Hypermesh and ANSYS). 10° and 30° taper, 3 and 5 mm preparation height and shoulder and chamfer finish lines were used. Type 1 Glass ionomer cement with 24 μm lute width was taken and the model was loaded under 100 N horizontal point load, v...

  1. Proposal for fabrication-tolerant SOI polarization splitter-rotator based on cascaded MMI couplers and an assisted bi-level taper

    OpenAIRE

    Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan

    2014-01-01

    A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM0 mode into the TE1 mode, which will output as the TE0 mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed dev...

  2. Proposal for fabrication-tolerant SOI polarization splitter-rotator based on cascaded MMI couplers and an assisted bi-level taper.

    Science.gov (United States)

    Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan

    2014-11-17

    A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM(0) mode into the TE(1) mode, which will output as the TE(0) mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed device has a polarization diversity, especially in the booming 100 Gb/s coherent optical communications based on silicon photonics technology. PMID:25402029

  3. Method for improving the spectral flatness of the supercontinuum at 1.55 μm in tapered microstructured optical fibers

    International Nuclear Information System (INIS)

    We propose a method for enhancing the flatness of a supercontinuum centered at 1.55 μm by the use of specially designed tapered microstructured optical fibers (MOFs). Based on the procedure presented one can determine the linear taper profile parameters and the optimum launching conditions needed to achieve the broadest supercontinuum spectra (SC) and the best spectra flatness. We quantify the maximally broad and flat SC using the calculated standard deviation of the spectra at the required wavelength range and show that it is possible to obtain significantly better results than those obtained by using an untapered fiber.

  4. Numerical modelling of physical processes in a ballistic laboratory setup with a tapered adapter and plastic piston used for obtaining high muzzle velocities

    International Nuclear Information System (INIS)

    Numerical modelling of a ballistic setup with a tapered adapter and plastic piston is considered. The processes in the firing chamber are described within the framework of quasi- one-dimensional gas dynamics and a geometrical law of propellant burn by means of Lagrangian mass coordinates. The deformable piston is considered to be an ideal liquid with specific equations of state. The numerical solution is obtained by means of a modified explicit von Neumann scheme. The calculation results given show that the ballistic setup with a tapered adapter and plastic piston produces increased shell muzzle velocities by a factor of more than 1.5-2

  5. Method for improving the spectral flatness of the supercontinuum at 1.55 μm in tapered microstructured optical fibers

    Science.gov (United States)

    Vukovic, N.; Broderick, N. G. R.

    2010-10-01

    We propose a method for enhancing the flatness of a supercontinuum centered at 1.55 μm by the use of specially designed tapered microstructured optical fibers (MOFs). Based on the procedure presented one can determine the linear taper profile parameters and the optimum launching conditions needed to achieve the broadest supercontinuum spectra (SC) and the best spectra flatness. We quantify the maximally broad and flat SC using the calculated standard deviation of the spectra at the required wavelength range and show that it is possible to obtain significantly better results than those obtained by using an untapered fiber.

  6. Lewy Body Disease

    Science.gov (United States)

    Lewy body disease is one of the most common causes of dementia in the elderly. Dementia is the loss of mental ... to affect normal activities and relationships. Lewy body disease happens when abnormal structures, called Lewy bodies, build ...

  7. Body Odor (For Girls)

    Science.gov (United States)

    ... Gynecology Medical Conditions Nutrition & Fitness Emotional Health Body Odor Posted under Health Guides . Updated 26 June 2015. + ... moisture, your body cools down. Where does body odor come from? When sweat mixes with the natural ...

  8. Body & Lifestyle Changes

    Science.gov (United States)

    ... Close X Home > Pregnancy > Body & lifestyle changes Body & lifestyle changes E-mail to a friend Please fill ... between pregnancies Nutrition, weight & fitness Prenatal care Body & lifestyle changes Is it safe? Labor & birth Postpartum care ...

  9. Inclusion Body Myositis

    Science.gov (United States)

    ... Awards Enhancing Diversity Find People About NINDS NINDS Inclusion Body Myositis Information Page Table of Contents (click ... and Information Additional resources from MedlinePlus What is Inclusion Body Myositis? Inclusion body myositis (IBM) is one ...

  10. Foreign body orbital cyst

    DEFF Research Database (Denmark)

    Yazdanfard, Younes; Heegard, Steffen; Fledelius, Hans C.;

    2001-01-01

    Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology......Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology...

  11. Tapered Double-layer EBG Structure Filter%一种双层渐变的EBG结构滤波器

    Institute of Scientific and Technical Information of China (English)

    沙莎; 田雨波

    2011-01-01

    电磁带隙(EBG)结构在微波波段具有广泛的应用,该文研究了一种双层渐变的EBG结构,该结构的接地板上刻蚀了6个周期性的圆,贴片是由6个蝶形单元组成,通过仿真实验确定了圆的半径和与蝶形单元的相对位置.与传统的电磁带隙结构相比,该结构具有小型化和结构紧凑的特点.同时还研究了一种在接地板上刻蚀非周期性圆的结构,此时圆的半径按照渐变函数有规律的变化,结果表明,渐变形式的引入减小了电磁带隙结构的通带波纹,这使得电磁带隙结构具有很好的阻带特性和较小的通带波纹.%Electromagnetic band gap ( EBG) structures are widely used in microwave field. A tapered dual-plane EBG structures filter is presented in this paper. This filter includes 6 uniform circles etched in the ground plane and 6 bow-tie cells. The relative positions of circles and bow-tie cells are determined by simulation. Compared with general EBG structures, this filter is small and compact. Moreover, this paper also studies the frequency characteristics of the various circles etched in the ground plane with different tapers. The computing result shows that different tapers can obviously eliminate the ripples in the pass band caused by the periodicity of the EBG structure. This filter is with excellent transmission characteristic in stop band and small ripples in pass band simultaneously.

  12. Low-temperature cross-talk magnetic-field sensor based on tapered all-solid waveguide-array fiber and magnetic fluids.

    Science.gov (United States)

    Miao, Yinping; Ma, Xixi; Wu, Jixuan; Song, Binbin; Zhang, Hao; Zhang, Kailiang; Liu, Bo; Yao, Jianquan

    2015-08-15

    A compact fiber-optic magnetic-field sensor based on tapered all-solid waveguide-array fiber (WAF) and magnetic fluid (MF) has been proposed and experimentally demonstrated. The tapered all-solid WAF is fabricated by using a fusion splicer, and the sensor is formed by immersing the tapered all-solid WAF into the MF. The transmission spectra have been measured and analyzed under different magnetic-field intensities. Experimental results show that the acquired magnetic-field sensitivity is 44.57 pm/Oe for a linear magnetic-field intensity range from 50 to 200 Oe. All-solid WAF has very similar thermal expansion coefficient for high- and low-refractive-index glasses, so mode profile is not affected by thermal drifts. Also, magnetically induced refractive-index changes into the ferrofluid are of the order of ∼5×10(-2), while the corresponding thermally induced refractive-index changes into the ferrofluid are expected to be lower. The temperature response has also been detected, and the temperature-induced wavelength shift perturbation is less than 0.3 nm from temperature of 26.9°C-44°C. The proposed magnetic-field sensor has such advantages as low temperature sensitivity, simple structure, and ease of fabrication. It also indicates that the magnetic-field sensor based on tapered all-solid WAF and MF is helpful to reduce temperature cross-sensitivity for the measurement of magnetic field. PMID:26274690

  13. A Comparison of Vibroacoustic Response of Isotropic Plate with Attached Discrete Patches and Point Masses Having Different Thickness Variation with Different Taper Ratios

    Directory of Open Access Journals (Sweden)

    Bipin Kumar

    2016-01-01

    Full Text Available A comparison of sound radiation behavior of plate in air medium with attached discrete patches/point masses having different thickness variations with different taper ratio of 0.3, 0.6, and 0.9 is analysed. Finite element method is used to find the vibration characteristics while Rayleigh integral is used to predict the sound radiation characteristics. Minimum peak sound power level obtained is at a taper ratio of 0.6 with parabolic increasing-decreasing thickness variation for plate with four discrete patches. At higher taper ratio, linearly increasing-decreasing thickness variation is another alternative for minimum peak sound power level suppression with discrete patches. It is found that, in low frequency range, average radiation efficiency remains almost the same, but near first peak, four patches or four point masses cause increase in average radiation efficiency; that is, redistribution of point masses/patches does have effect on average radiation efficiency at a given taper ratio.

  14. 1.5 W green light generation by single-pass second harmonic generation of a single-frequency tapered diode laser

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Andersen, Peter E.; Sumpf, Bernd; Hasler, Karl-Heinz; Erbert, Goetz; Petersen, Paul Michael

    2009-01-01

    More than 1.5 W of green light at 531 nm is generated by singlepass second harmonic generation in periodically poled MgO:LiNbO3. The pump laser is a high power tapered laser with a distributed Bragg reflector etched in the ridge section of the laser to provide wavelength selectivity. The output...

  15. Body Matters: Narratives of the Body

    OpenAIRE

    Asandi, Iren; Filipovska, Kalina; Neault, Megan; Olsen, Sara Høier

    2014-01-01

    This project engages the notion of the subjective body in a pasture of social constructions in order to gather an understanding of the narratives created by women about their bodies in relation to cosmetic surgery. The empirical data for this project comes from our virtual ethnographic research on the various forums from the MyLooks website. Moreover, perspectives regarding the body, beauty ideals and theoretical positions from Kathryn Morgan and Kathy Davis fill out the structure of the proj...

  16. Development of a tapered cell drift chamber II: operation in high magnetic fields and different gas pressures

    International Nuclear Information System (INIS)

    Several designs for drift cells have been constructed and tested in an electron beam at DESY. The designs tested consisted of pairs of adjacent tapered cells, of eight sense wires each, to simulate a portion of a layer of drift cells in a central tracking detector. Tests were made to study the operation and resolution of the drift cells under a variety of conditions. Ar:C2H6 (50:50) and Ar:CO2:CH4 (90:9:1) gas mixtures were used at absolute pressures of one to four bar for the former and at one bar for the latter. Measurements were made at different electric drift fields in conjunction with magnetic fields varying from 0 to 1.82 T. Aspects of the construction, electronics and operation are discussed and results regarding the resolution as a function of drift distance and operating conditions are presented with some model calculations. (author)

  17. High-power quantum-dot tapered tunable external-cavity lasers based on chirped and unchirped structures.

    Science.gov (United States)

    Haggett, Stephanie; Krakowski, Michel; Montrosset, Ivo; Cataluna, Maria Ana

    2014-09-22

    A high-power tunable external cavity laser configuration with a tapered quantum-dot semiconductor optical amplifier at its core is presented, enabling a record output power for a broadly tunable semiconductor laser source in the 1.2 - 1.3 µm spectral region. Two distinct optical amplifiers are investigated, using either chirped or unchirped quantum-dot structures, and their merits are compared, considering the combination of tunability and high output power generation. At 1230 nm, the chirped quantum-dot laser achieved a maximum power of 0.62 W and demonstrated nearly 100-nm tunability. The unchirped laser enabled a tunability range of 32 nm and at 1254 nm generated a maximum power of 0.97 W, representing a 22-fold increase in output power compared with similar narrow-ridge external-cavity lasers at the same current density. PMID:25321756

  18. Observation of a push force on the end face of a nm fiber taper exerted by outgoing light

    CERN Document Server

    She, Weilong; Feng, Raohui

    2008-01-01

    There are two different proposals for the momentum of light in a transparent dielectric of refractive index n: Minkowski's version nE/c and Abrahm's version E/(nc), where E and c are the energy and vacuum speed of light, respectively. Despite many tests and debates over nearly a century, momentum of light in a transparent dielectric remains controversial. In this Letter, we report a direct observation of the inward push force on the end face of a free nm fiber taper exerted by the outgoing light. Our results clearly support Abraham momentum. Our experiment also indicates an inward surface pressure on a dielectric exerted by the incident light, different from the commonly recognized pressure due to the specular reflection. Such an inward surface pressure by the incident light may be useful for precise design of the laser-induced inertially-confined fusion.

  19. Effects of unsteadiness and non-Newtonian rheology on blood flow through a tapered time-variant stenotic artery

    Directory of Open Access Journals (Sweden)

    A. Zaman

    2015-03-01

    Full Text Available A two-dimensional model is used to analyze the unsteady pulsatile flow of blood through a tapered artery with stenosis. The rheology of the flowing blood is captured by the constitutive equation of Carreau model. The geometry of the time-variant stenosis has been used to carry out the present analysis. The flow equations are set up under the assumption that the lumen radius is sufficiently smaller than the wavelength of the pulsatile pressure wave. A radial coordinate transformation is employed to immobilize the effect of the vessel wall. The resulting partial differential equations along with the boundary and initial conditions are solved using finite difference method. The dimensionless radial and axial velocity, volumetric flow rate, resistance impedance and wall shear stress are analyzed for normal and diseased artery with particular focus on variation of these quantities with non-Newtonian parameters.

  20. Stable Fixation of a Cementless, Proximally Coated, Double Wedged, Double Tapered Femoral Stem in Total Hip Arthroplasty

    DEFF Research Database (Denmark)

    Nebergall, Audrey K; Rolfson, Ola; Rubash, Harry E;

    2016-01-01

    BACKGROUND: The objective of this 5-year prospective study of 51 hips was to assess migration of a cementless tapered femoral stem using radiostereometric analysis (RSA), plain radiographs (radiolucencies), and patient-reported outcome measures (PROMs). METHODS: Forty-seven patients (51 hips......) agreed to participate in this prospective RSA study. All patients received a Taperloc stem. Tantalum beads were inserted into the femoral bone surrounding the stem to measure migration using RSA. RSA films, plain radiograph, and PROM follow-up were obtained immediately after surgery, 6 months, 1, 2, 3...... year remain stable at 5 years. RSA was the most sensitive method of detection for stems at greater risk for potential future failure. This report adds contributions to the positive results associated with this type of fixation. The results at 5 years showed excellent midterm survivorship in this cohort...